JP2017121158A - Motor and electric tool - Google Patents

Abstract

Provided are a motor and an electric tool capable of suppressing a difference in resistance values of a plurality of coils connected in parallel without increasing the size of a motor body.
[Solution]
In a motor 5 including a stator 53 having an annular portion 531 and a plurality of teeth portions 532 provided on the inner peripheral surface of the annular portion 531 and projecting in the radial direction of the annular portion 531, A plurality of coil winding portions 532A-1 and 532A-2 having the same length L in the radial direction are provided in the tooth portion 532, and each of the plurality of coil winding portions 532A-1 and 532A-2 of each tooth portion 532 is provided. The coils C1 and C2 having the same number of turns are wound.
[Selection] Figure 10

Description

  The present invention relates to a motor and an electric tool including the motor.

  In recent years, brushless motors are often used in electric tools that rotate and drive tools such as drills, drivers, and saw blades using a motor. In the brushless motor, one or a plurality of coils are wound around a tooth portion provided on the inner periphery of the stator. For example, in the case of a three-phase six-pole brushless motor, two coils are connected in series to each of the U phase, V phase, and W phase, and the three phases are star-connected. The inverter circuit switches energization to each phase to obtain a predetermined output.

  In such a brushless motor, since the resistance value of the coils connected in series is increased, there is a problem in that high output is hindered. Further, in order to reduce the resistance value, it is conceivable to increase the wire diameter of the coil. However, in that case, there is a problem that the motor body is enlarged.

  In order to solve the above-described problem, conventionally, a brushless motor has been reduced in size and output by connecting coils of each phase in parallel (see Patent Document 1 below).

  By the way, the winding of the coil around the teeth portion is usually performed one by one by a winding machine. When a plurality of coils connected in parallel are wound around the same tooth, the winding machine first winds the first coil inside the teeth portion, and then the second coil outside the first coil. Wrap.

Japanese Patent Laying-Open No. 2015-162985

  When a plurality of coils are wound around the same tooth as described above, the inner coil and the outer coil have different lengths even when the number of turns is the same, resulting in a difference in resistance value. That is, a plurality of coils having different resistance values are connected in parallel. In this case, the coil that is not energized is also refluxed by the rotating magnetic field of the rotor. As a result, there has been a problem that the rotation of the rotor is decelerated and the output is reduced. In addition, when all the coils are wound inwardly, that is, when all the coils are wound so as to be in contact with the surface of the teeth portion, the coils having the same number of turns have the same length, but the teeth portion And the dimension of the stator becomes large, and there is a problem that the motor body is enlarged.

  In view of such a problem, an object of the present invention is to provide a motor and an electric tool that can suppress a difference in resistance values of a plurality of coils connected in parallel to each other without increasing the size of the motor body. .

  In order to solve the above-described problems, a motor according to the present invention includes a stator having an annular portion, and a plurality of teeth portions that are provided on the inner peripheral surface of the annular portion and project in the radial direction of the annular portion, and the teeth. A coil wound around the first portion, and the coil includes a first coil wound around a radially outer portion of the tooth portion in one of the plurality of tooth portions, and the tooth portion than the first coil. And a second coil wound around the radially inner portion.

  According to such a configuration, the coil lengths of the coils wound around one tooth portion can be made substantially the same without increasing the size of the motor body. Therefore, it is possible to suppress a difference in resistance value of each coil, and it is possible to prevent a decrease in output even when these coils are connected in parallel.

  In the motor described above, each tooth portion includes a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction. In each tooth portion, the first coil is a plurality of coils. It is preferable that the second coil is wound around a radially inner portion of the plurality of coil winding portions.

  According to such a configuration, in each tooth portion, a plurality of coil winding portions having the same length in the radial direction are defined. Therefore, when a plurality of coils are wound around one tooth portion with the same number of turns. This makes it possible to suppress the occurrence of a difference in the coil length of each coil without increasing the size of the motor body. Therefore, it is possible to suppress a difference in resistance value of each coil, and it is possible to prevent a decrease in output even when these coils are connected in parallel.

  In the motor described above, it is preferable that the first coil and the second coil have the same number of turns in each of the tooth portions.

  According to such a configuration, it is possible to suppress a difference between the coil length and the resistance value of the plurality of coils wound around each coil winding part.

  Furthermore, in each of the tooth portions, each coil preferably has the same number of turns in the radial direction.

  According to such a configuration, it is possible to reliably prevent a difference from occurring in the coil length and the resistance value of the plurality of coils wound around each coil winding portion.

  Moreover, it is preferable that each coil has the same wire diameter in each tooth part.

  According to such a configuration, since the wire diameters and coil lengths of the plurality of coils wound around each tooth portion are the same, it is possible to suppress a difference in resistance values of these coils. Therefore, even when these coils are connected in parallel, it is possible to prevent a decrease in output due to the occurrence of reflux.

  Moreover, it is preferable that the some coil wound by each teeth part is mutually connectable in parallel.

  According to such a configuration, it is possible to prevent reflux from occurring in the coils connected in parallel, so that a reduction in output is prevented. Moreover, the output can be stabilized regardless of the power source by switching the connection method according to the power source.

  In addition, the plurality of tooth portions includes a plurality of tooth sets including a first tooth portion and a second tooth portion facing each other in the radial direction, and the first coil is wound around a radially outer portion of the first tooth portion. Is wound around the radially inner portion of the second tooth portion via the connecting wire, and the second coil wound around the radially inner portion of the second tooth portion is the first teeth portion via the connecting wire It is preferable to be wound around the radially outer portion.

  According to such a configuration, when a plurality of coils wound around the first tooth portion and a plurality of coils wound around the second tooth portion are connected in series to form a plurality of coil sets, the coil Since the lengths of the connecting wires connecting between the coils are the same between the coil sets, the overall lengths of the coil sets can be made the same. Accordingly, since it is possible to suppress the difference in resistance value between the coil sets, it is possible to prevent a decrease in output even when these coil sets are connected in parallel.

  A motor according to another aspect of the present invention includes a stator having an annular portion and a plurality of tooth portions provided on an inner peripheral surface of the annular portion and projecting in a radial direction of the annular portion. It has a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction, and each of the plurality of coil winding portions of each tooth portion includes a coil having the same number of turns. Features.

  According to such a configuration, a plurality of coil winding portions having the same length in the radial direction are defined in each tooth portion, and the same number of coils are wound around each coil winding portion. The coil length of each coil can be made substantially the same without increasing the size. Therefore, it is possible to suppress a difference in resistance value of each coil, and it is possible to prevent a decrease in output even when these coils are connected in parallel.

  In the motor described above, in each of the plurality of coil winding portions of each tooth portion, the coils preferably have the same number of turns in the radial direction.

  According to such a configuration, it is possible to prevent a difference from occurring in the coil length and the resistance value of the coil wound around each coil winding portion.

  Furthermore, in each of the plurality of coil winding portions of each tooth portion, the coils preferably have the same wire diameter.

  According to such a configuration, since the linearity and the coil length of the coils wound around the coil winding portions are the same, it is possible to prevent the resistance values of these coils from being different. Therefore, even when these coils are connected in parallel, it is possible to prevent a decrease in output due to the occurrence of reflux.

  Moreover, it is preferable that the some coil wound by the some coil winding part of each teeth part can mutually switch a parallel connection and a series connection.

  According to such a configuration, it is possible to prevent reflux from occurring in the coils connected in parallel, so that a reduction in output is prevented. Moreover, the output can be stabilized regardless of the power source by switching the connection method according to the power source.

  Further, the plurality of tooth portions are formed of a plurality of tooth sets including a first tooth portion and a second tooth portion that are opposed to each other in the radial direction, and are wound around a coil winding portion that is located on the radially outer side of the first tooth portion. The first coil to be wound is wound around the coil winding portion located on the radially inner side of the second tooth portion via the connecting wire and wound on the coil winding portion located on the radially outer side of the second tooth portion. It is preferable that the 2nd coil rotated is wound by the coil winding part located in the radial inside of the 1st teeth part via a connecting wire.

  According to such a configuration, when a plurality of coils wound around the first tooth portion and a plurality of coils wound around the second tooth portion are connected in series to form a plurality of coil sets, the coil Since the lengths of the connecting wires connecting between the coils are the same between the coil sets, the overall length and the resistance value of each coil set can be made the same. Therefore, when these coil sets are connected in parallel to each other, it is possible to prevent a decrease in output.

  Each of the teeth portions includes a plurality of coil winding portions defined side by side in the radial direction, and has ribs that project between two adjacent coil winding portions among the plurality of coil winding portions. It is preferable.

  According to such a configuration, since the ribs are provided between the coil winding portions, a plurality of coils can be wound uniformly even when the coils are wound by the winding machine.

  In addition, a motor according to another aspect of the present invention includes a stator having an annular portion, and at least a pair of teeth portions provided on an inner peripheral surface of the annular portion and projecting in the radial direction of the annular portion, and a pair of teeth portions. A first coil including a pair of first winding portions wound around the first coil, and a second coil including a pair of second winding portions wound around the pair of teeth portions, The coil and the second coil have substantially the same resistance value.

  According to such a configuration, it is possible to suppress a difference in resistance value of each coil without increasing the size of the motor body.

  The pair of first winding portions and the pair of second winding portions preferably have substantially the same length.

  According to such a configuration, it is possible to suppress a difference in resistance value of each coil without increasing the size of the motor body.

  Further, the winding positions of the first coil and the second coil in one of the pair of teeth portions and the winding positions of the first coil and the second coil in the other of the pair of teeth portions are reversed. It is preferable.

  According to such a configuration, it is possible to suppress a difference in resistance value of each coil without increasing the size of the motor body.

  Each of the pair of tooth portions includes a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction, and the first coil has a radial direction in one of the tooth portions. One of the pair of first winding portions is wound around the coil winding portion located on the outside, and the other of the pair of first winding portions is wound on the coil winding portion located on the radially inner side in the other tooth portion. The second coil is wound around one of the pair of second winding portions around the coil winding portion located radially inward in one tooth portion, and in the radial direction in the other tooth portion. It is preferable that the other of the pair of second winding portions is wound around the coil winding portion located outside.

  According to such a configuration, a plurality of winding portions wound around one tooth portion and a plurality of winding portions wound around the other tooth portion are connected in series to form a plurality of coils. In addition, since the length of the connecting wire connecting the winding portions is substantially the same between the coils, the overall length and the resistance value of each coil can be made substantially the same. Therefore, even when these coils are connected in parallel to each other, it is possible to prevent a decrease in output.

  The first coil further includes a first crossover portion that connects one end of the pair of first winding portions to the other end, and the second coil includes a pair of second winding portions. It is preferable that a second crossover portion that connects one end and the other end is further included, and that the first crossover portion and the second crossover portion have different lengths.

  According to such a configuration, since the connecting wire connecting the winding portions is configured to have a different length between the coils, the length of each winding portion wound around one tooth portion may be different. The length of each coil can be made substantially the same. Therefore, it is possible to suppress the difference between the resistance values of the coils.

  Moreover, it is preferable that the first coil and the second coil have substantially the same length.

  According to this configuration, it is possible to reliably suppress a difference between the resistance values of the first coil and the second coil.

  In addition, the first coil includes a first crossover portion that connects one end of the pair of first winding portions to the other end, one other end of the pair of first winding portions, and the other end of the other. A pair of first connection portions connectable to the ends, and the second coil includes a second crossover portion connecting one end and the other end of the pair of second winding portions. A pair of second connecting portions connectable to one other end and the other other end of the pair of second winding portions, respectively, wherein the first coil and the second coil are a pair of first coils 1 connection part and a pair of 2nd connection part can mutually be connected in parallel, and one side of a pair of 1st connection part has resistance which can be connected to one other end of a pair of 1st coil parts Is preferred.

  According to such a configuration, even when the coil lengths of a plurality of coils connected in parallel to each other are different, the resistance value of each coil can be made substantially the same by connecting the resistors in series to the coil having a short coil length. Become.

  The first coil further includes a third connecting portion capable of connecting the other end of the pair of first winding portions and the other end of the pair of second winding portions, and the first coil includes the pair of first windings. The coil further includes a first switching unit capable of switching a connection destination of one other end of the winding unit to either one of the pair of first connection units or the third connection unit, and the second coil includes a pair of first coils The second switching unit further includes a second switching unit capable of switching the connection destination of one other end of the two winding units to either one of the pair of second connection units and the third connection unit, the first switching unit and the second switching unit The first and second coils are switched by switching the connection destination of one other end of the pair of first winding portions and the connection destination of one other end of the pair of second winding portions to the third connection portion. The two coils are preferably connected in series with each other.

  According to such a configuration, when the first coil and the second coil are connected in parallel to each other, the resistance value of each coil can be made substantially the same by connecting the resistor in series to the coil having a short coil length. On the other hand, when switching from the parallel connection to the series connection, it is possible to place a resistor outside the connection path. Therefore, it is possible to prevent a decrease in output in both cases of parallel connection and series connection.

  In addition, a power tool according to the present invention includes the motor having the above-described configuration and an output unit driven by the motor.

  According to such a configuration, it is possible to suppress a difference in the resistance values of a plurality of coils provided in the motor and connected in parallel to each other without increasing the size of the tool body, thereby preventing a decrease in output.

  According to the motor and the electric tool according to the present invention, it is possible to suppress a difference in resistance values of a plurality of coils connected in parallel to each other without increasing the size of the motor main body and the tool main body.

It is a side view which shows the external appearance of the tabletop circular saw which concerns on embodiment of this invention. It is a front view which shows the external appearance of the tabletop circular saw which concerns on embodiment of this invention. It is a fragmentary sectional front view which shows the internal structure of the cutting part case of the desk circular saw which concerns on embodiment of this invention. It is a circuit diagram which shows the connection state of two U-phase coil parts, two V-phase coil parts, and two W-phase coil parts in the motor of the desktop circular saw according to the embodiment of the present invention. Fig. 2 shows a state in which the coil portions are connected in series. It is a circuit diagram which shows the connection state of two U-phase coil parts, two V-phase coil parts, and two W-phase coil parts in the motor of the desktop circular saw according to the embodiment of the present invention. Fig. 2 shows a state in which the coil portions are connected in parallel. It is a front view which shows the structure of the stator in the motor of the desktop circular saw which concerns on the 1st Embodiment of this invention. It is VII-VII sectional drawing of FIG. It is VIII-VIII sectional drawing of FIG. It is a figure (the 1) explaining the winding method of the coil in 1st Embodiment. It is FIG. (2) explaining the winding method of the coil in 1st Embodiment. It is a front view which shows the stator and connecting wire in 1st Embodiment. It is a side view which shows the stator and connecting wire in 1st Embodiment. It is a top view which shows the stator and connecting wire in 1st Embodiment. It is a front view which shows the structure of the stator in the motor of the desktop circular saw which concerns on the 2nd Embodiment of this invention. It is XV-XV sectional drawing of FIG. It is a figure which shows the winding part of the coil in 2nd Embodiment. It is the elements on larger scale which show the winding part of the coil in 2nd Embodiment. It is the elements on larger scale which show the winding part of the coil in a 1st modification. It is the elements on larger scale which show the winding part of the coil in a 2nd modification. It is a conceptual diagram explaining the connection state of the coil in a 3rd modification. It is a key map explaining the connection state of the coil in the 4th modification, and shows the state where a mutual coil part is in series connection in each phase. It is a key map explaining the connection state of the coil in the 4th modification, and shows the state where a mutual coil part is in parallel connection in each phase. It is a front view which shows the stator and connecting wire in a 4th modification. It is a side view which shows the stator and connecting wire in a 4th modification. It is a top view which shows the stator and connecting wire in a 4th modification. It is explanatory drawing which shows arrangement | positioning of the crossover part of the coil in a 4th modification, (a) is a figure explaining arrangement | positioning of the crossover line of a 1st coil part, (b) is a crossover of a 2nd coil part. It is a figure explaining arrangement | positioning of a line. It is a key map explaining the connection state of the coil in the 5th modification, and shows the state where a mutual coil part is in series connection in each phase. It is a key map explaining the connection state of the coil in the 5th modification, and shows the state where the mutual coil part is connected in parallel in each phase. It is a right view of the circular board | substrate in a 5th modification.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, the case where the present invention is applied to a three-phase brushless DC motor and a tabletop circular saw driven by the three-phase brushless DC motor will be described as an example.

  In the following description, when referring to a specific numerical value, for example, when referring to an angle such as “60 °”, not only when the numerical value is completely coincident with the numerical value, but also when the numerical value is substantially the same Shall also be included. In addition, when referring to positional relationship, dimensions, etc., for example, when referring to parallel, orthogonal, opposite, identical, etc., not only when it is completely parallel, orthogonal, opposite, identical, etc., but also substantially parallel, substantially The case of being orthogonal, substantially opposite, substantially identical, etc. is also included.

  First, a desktop circular saw 1 as an example of an electric tool according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is defined as an upward direction, a downward direction as a downward direction, a front direction as a forward direction, and a rear direction as a backward direction. Further, when the desktop circular saw 1 is viewed from behind, the left is defined as the left direction and the right is defined as the right direction.

  1 and 2 are a side view and a front view showing the external appearance of the tabletop circular saw 1, respectively. 1 and 2, a battery pack S is attached to the tabletop circular saw 1. As shown in FIGS. 1 and 2, the tabletop circular saw 1 includes a base portion 2, a cutting portion 3, a cutting portion support portion 4, and a motor 5. A circular saw blade 32C is rotatably supported by the cutting unit 3, and the tabletop circular saw 1 cuts the workpiece W with the circular saw blade 32C.

  The base portion 2 is a portion on which the material to be cut W can be placed, and includes a base 21, a turntable 22, a fence 23, and a power cord 24.

  The base 21 has a structure that can be placed on a floor surface or the like, and has a substantially rectangular shape in plan view. The turntable 22 is embedded in the base 21. The upper surface of the turntable 22 is flush with the upper surface of the base 21. The upper surface of the base portion 2 is formed together with the upper surface of the base 21 so that the workpiece W can be placed thereon. Further, the turntable 22 is configured to be rotatable with respect to the base 21 via a rotation shaft orthogonal to the upper surface thereof. When the turntable 22 is rotated, the cutting unit 3 and the cutting unit support unit 4 are configured to rotate integrally with the turntable 22.

  The fence 23 is provided on the upper surface of the base 21. The fence 23 has a contact surface 23 </ b> A that is a surface perpendicular to the upper surface of the base 21 and can contact the material W to be cut. When cutting the workpiece W, the cutting operation is performed in a state where one surface of the workpiece W is in contact with the contact surface 23A of the fence 23. Thereby, the position shift of the material W to be cut during the cutting operation can be prevented, and a stable cutting operation can be performed. Further, when the turntable 22 is rotated with respect to the base 21, the position of the cutting portion 3 that rotates integrally with the turntable 22 changes with respect to the fence 23, and the fence 23 and the side surface of the circular saw blade 32C are changed. The angle between changes. Thereby, it becomes possible to cut the workpiece W that is in contact with the contact surface 23A of the fence 23 at various angles.

  The power cord 24 extends from substantially the center in the front-rear direction of the right side surface of the base 21 toward the rear, and the tip thereof is configured to be connectable to a commercial power source P that is an external AC power source, such as a household outlet. Yes.

  The cutting portion support portion 4 is a portion that supports the cutting portion 3 so as to be swingable in the vertical direction with respect to the base portion 2 and to tilt the side surface of the circular saw blade 32C with respect to the upper surface of the base portion 2, 41, a holder 42, a guide bar 43, a slider 44, and a hinge 45.

  The tilt shaft 41 is an axis extending in the front-rear direction supported substantially parallel to the upper surface of the turntable 22 at the rear end portion of the turntable 22. The holder 42 is a portion extending in the vertical direction, and is provided so as to be tiltable with respect to the turntable 22 via a tilting shaft 41. The holder 42 can be tilted by a predetermined angle in a left direction and a right direction in a front view from a posture perpendicular to the upper surface of the turntable 22 and can be fixed at a desired rotation position in a tiltable range. . Thereby, the circular saw blade 32C is also fixed at the same inclination angle, and so-called inclination cutting is possible.

  The guide bar 43 consists of two bars, and each bar extends from the upper part of the holder 42 in the forward direction substantially parallel to each other. The slider 44 is inserted through the guide bar 43 and is slidable in the front-rear direction with respect to the guide bar 43. The hinge 45 connects the cutting portion 3 to the slider 44 so as to be swingable. By sliding the slider 44 in the front-rear direction with respect to the guide bar 43, the cutting part 3 moves in the front-rear direction together with the slider 44.

  The cutting part 3 is a part that rotatably supports the circular saw blade 32 </ b> C, and includes a cutting part case 31, a saw blade case 32, and a battery mounting part 33.

  FIG. 3 is a partial cross-sectional front view showing the inside of the cutting portion case 31 of the tabletop circular saw 1. As shown in FIG. 3, the motor 5, the rotation transmission mechanism 6, the motor board part 7, and the control board part 8 are accommodated inside the cutting part case 31. Details of the inside of the cutting part case 31 will be described later.

  In addition, as shown in FIGS. 1 and 2, the cutting portion case 31 is provided with an operation handle 31 </ b> A at the front upper portion. The operation handle 31A is provided with a trigger switch 31B for controlling the rotation and stop of the motor 5.

  As shown in FIGS. 1 and 2, the cutting part case 31 is rotatably connected to the slider 44 via a hinge 45 and is attached to the base part 2 so as to be swingable in the direction of approaching and separating. Yes. The cutting part case 31 is biased upward by a spring (not shown) provided around the hinge 45. For this reason, unless an operating force is applied downward to the operating handle 31A, the cutting portion 3 is restricted to a top dead center (state shown in FIG. 1) by a stopper provided around the hinge 45.

  Further, as shown in FIGS. 1 and 3, the cutting portion case 31 includes a plurality of intake ports 31a, 31b and exhaust ports 31c for sucking and discharging outside air into the cutting portion case 31 by a fan 51A described later. Is formed.

  The saw blade case 32 is formed integrally with the cutting portion case 31, and is configured to cover the upper portion of the circular saw blade 32C. The saw blade case 32 has an output shaft 32A and a protective cover 32B.

  The output shaft 32A is a shaft extending in the left-right direction, and is rotatably supported by the saw blade case 32. A circular saw blade 32C is attached to the output shaft 32A, and the circular saw blade 32C rotates as the output shaft 32A rotates.

  The protective cover 32B is a member for covering a portion of the circular saw blade 32C exposed from the saw blade case 32, and is supported so as to be rotatable along the inner surface of the saw blade case 32. When the operation handle 31A is operated and the cutting portion 3 is pushed down from the state located at the top dead center toward the bottom dead center, the protective cover 32B is exposed in a direction in which the lower part of the circular saw blade 32C is exposed by a link mechanism (not shown). It turns and it is in the state which can cut | disconnect the workpiece W.

  The battery mounting portion 33 extends upward from the upper part of the rear end of the cutting portion case 31, and is configured to be detachable from the battery pack S. The battery pack S includes a battery set having a plurality of secondary batteries, for example, and serves as a drive source for the motor 5. By sliding the battery pack S downward with respect to the battery mounting portion 33, the battery pack S is mounted on the battery mounting portion 33, and by sliding upward, the battery pack S is detached from the battery mounting portion 33. .

  Next, the inside of the cutting part case 31 will be described. As shown in FIG. 3, the motor 5, the rotation transmission mechanism 6, the motor board part 7, and the control board part 8 are accommodated in a portion extending in the left-right direction inside the cutting part case 31.

  The motor 5 is a three-phase brushless DC motor in the present embodiment, and includes a rotating shaft 51, a rotor 52, and a stator 53.

  The rotating shaft 51 is a shaft extending in the left-right direction that is rotatably supported by the cutting portion case 31, and outputs a rotational driving force. The left end portion of the rotation shaft 51 is connected to the rotation transmission mechanism 6, and the rotational driving force of the rotation shaft 51 is transmitted to the rotation transmission mechanism 6. Further, a fan 51A for cooling the motor 5 is disposed on the right side of the connection portion of the rotating shaft 51 with the rotation transmission mechanism 6 so as to be rotatable integrally with the rotating shaft 51. Accordingly, the outside air sucked from the intake ports 31a and 31b cools the motor 5, the motor board unit 7, the control board unit 8 and the like, and is discharged from the exhaust port 31c.

  The rotor 52 is configured to include four sets of permanent magnets each having a north pole and a south pole, and three hall elements 73 are disposed at positions facing the permanent magnets.

  The stator 53 is provided radially outward of the rotor 52, and the rotor 52 is configured to be rotatable relative to the stator 53. Further, 12 coils are wound around the stator 53. The configuration of the stator 53 will be described later in detail.

  The rotation transmission mechanism 6 is a mechanism that transmits the rotational force of the rotation shaft 51 to the output shaft 32A, and is provided on the left side of the fan 51A. When the rotational force of the rotary shaft 51 is transmitted and the output shaft 32A is rotated, the circular saw blade 32C is rotated, and a cutting operation is possible.

  The motor board 7 includes a circular board 71 attached to the right end of the stator 53, six relays 72 having the same internal resistance value, and three hall elements 73. The circular substrate 71 has a substantially circular shape when viewed from the right side, and an insertion hole (not shown) penetrating in the left-right direction is formed at the center thereof. The rotating shaft 51 of the motor 5 is inserted through the insertion hole. The six relays 72 are arranged at 60 ° intervals in the circumferential direction on the right side surface of the circular substrate 71. Note that the relays 72 may be arranged randomly rather than at regular intervals. Similarly, the three Hall elements 73 are arranged at intervals of 60 ° in the circumferential direction on the left side surface of the circular substrate 71 and face the right side surface of the rotor 52.

  As shown in FIG. 3, the control board unit 8 includes a control board 81 disposed below the motor 5 and six FETs 81 </ b> A to 81 </ b> F. The control board 81 has a substantially rectangular shape when viewed from the front, and an inverter circuit including six FETs 81A to 81F is mounted on the front surface thereof.

  Next, the configuration of the stator 53 in the motor 5 of the tabletop circular saw 1 according to the first embodiment will be described in detail with reference to FIGS. 6 to 8. FIG. 6 is a front view showing the configuration of the stator 53 in the motor 5 of the tabletop circular saw 1 according to the first embodiment. 7 is a sectional view taken along line VII-VII in FIG. 6, and FIG. 8 is a sectional view taken along line VIII-VIII in FIG. In FIGS. 6 and 7, a lead wire (portion connected to the motor board portion 7) of the inner coil described later is not shown.

  The stator 53 includes an annular portion 531 and six teeth portions 532. The rotor 52 (FIG. 3) is disposed in the hollow portion inside the annular portion 531. In the following description, the radial direction means the radial direction of the annular portion 531, and the axial direction means the direction in which the rotating shaft 51 extends.

  The annular portion 531 has an annular shape and is arranged so that the rotation shaft 51 is at the center. The six teeth portions 532 are arranged on the inner peripheral surface of the annular portion 531 at intervals of 60 ° in the circumferential direction. Each tooth portion 532 has a coil winding portion 532A and a stopper portion 532B, and the surface thereof is covered with an insulator 532C made of a non-conductive material such as a resin.

  The coil winding portion 532 </ b> A is a portion having a rectangular cross section and a prismatic shape whose axial dimension is shorter than that of the annular portion 531, and protrudes radially inward from the inner peripheral surface of the annular portion 531. As shown in FIGS. 6 and 7, a conductive wire C forming a coil is wound around the coil winding portion 532A. The stopper portion 532B is provided at the front end portion of the coil winding portion 532A in the protruding direction, and restricts the drop of the conductive wire C from the coil winding portion 532A. The conductive wire C, the coil winding portion 532A, and the stopper portion 532B are insulated by the insulator 532C. 6 and 8, the conductive wire C is wound only around the coil winding portion 532 </ b> A of one tooth portion 532 for explanation.

  As shown on the left side of FIG. 8, two conductive wires, that is, a first conductive wire C1 and a second conductive wire C2 are wound around the coil winding portion 532A of each tooth portion 532. Of the coil winding portion 532A, the portion located on the annular portion 531 side, that is, on the radially outer side is defined as the outer coil winding portion 532A-1, and the portion located on the stopper portion 532B side, that is, on the radially inner side, is It is defined as the inner coil winding portion 532A-2. The outer coil winding portion 532A-1 and the inner coil winding portion 532A-2 are defined such that the radial length L and the surface area are the same. In the coil winding portion 532A shown on the left side of FIG. 8, the first conductive wire C1 is wound around the outer coil winding portion 532A-1, and the second conductive wire C2 is wound around the inner coil winding portion 532A-2. It is wound.

  The first conductive line C1 and the second conductive line C2 both have the same wire diameter φ (for example, φ = 1.1 mm) in the present embodiment, and are wound around the coil winding portion 532A with 9 turns. A coil is formed. Hereinafter, the coil formed by the first conduction line C1 is referred to as a first coil, and the coil formed by the second conduction line C2 is referred to as a second coil. In addition, a coil wound around the outer coil winding portion 532A-1 is referred to as an outer coil, and a coil wound around the inner coil winding portion 532A-2 is referred to as an inner coil. In the coil winding portion 532A shown on the left side of FIG. 8, the first coil corresponds to the outer coil, and the second coil corresponds to the inner coil.

  Similarly, the coil winding portion 532A of the other five tooth portions 532 is also provided with an outer coil winding portion 532A-1 on the annular portion 531 side, that is, on the radially outer side, and on the stopper portion 532B side, that is, the diameter. An inner coil winding portion 532A-2 is defined on the inner side in the direction. In each tooth portion 532, the outer coil winding portion 532A-1 and the inner coil winding portion 532A-2 are defined so that the radial length L and the surface area are the same. And either one of the 1st conduction | electrical_connection line C1 and the 2nd conduction | electrical_connection line C2 is wound by the outer side coil winding part 532A-1, and an outer side coil is formed. In addition, the other one of the first conducting wire C1 and the second conducting wire C2 is wound around the inner coil winding portion 532A-2 to form an inner coil. That is, 12 coils are wound around the stator 53.

  In the present embodiment, in each tooth portion 532, the length L in the radial direction of the outer coil winding portion 532A-1 and the inner coil winding portion 532A-2 is the wire diameter φ of the conducting wire C, respectively. It is prescribed to be approximately three times as large as.

  Next, a method for winding the conductive wire C around each coil winding portion 532A will be described in detail with reference to FIGS. 9 and 10 are partially enlarged views of FIG. 8, and are diagrams for explaining a coil winding method according to the first embodiment.

  Winding of the conductive wire C around the coil winding portion 532A is performed using a winding machine. Prior to winding of the conductive wire C, the block B is arranged on the front surface and the rear surface (not shown) of the inner coil winding portion 532A-2 as shown in FIG. That is, the block B is aligned with the front surface of the inner coil winding portion 532A-2 (the corner portion of the block B is aligned with the connecting portion between the stopper portion 532B and the inner coil winding portion 532A-2), and the inner coil winding is performed. Arranged in the section 532A-2. Block B prevents the first conductive wire C1 from being wound around the inner coil winding portion 532A-2 by the winding machine by blocking the front surface and the rear surface of the inner coil winding portion 532A-2. The block B is a prism having a rectangular cross section, and its radial length is substantially the same as the radial length L of the inner coil winding portion 532A-2.

  After arranging the block B, the first conductive wire C1 is wound nine times around the outer coil winding part 532A-1 using a winding machine. The winding machine first winds the first conductive wire C1 three times on the surface of the outer coil winding portion 532A-1 in order from the radially outer side to the inner side. At this time, the first coil is wound around the surface of the outer coil winding portion 532A-1 so that three first conductive wires C1 are arranged. The first conductive line C1 that appears to be arranged in three is referred to as a first conductive line layer C11.

  When the first conductive wire C1 is wound three times, the winding machine is restricted by the block B, and the first conductive wire C1 is wound three times in order from the radially inner side to the outer side outside the first conductive wire layer C11. Wind. At this time, the outer coil winding portion 532A-1 is wound such that three first conductive wires C1 are arranged outside the first conductive wire layer C11. The outer first conductive line C1 that appears to be lined up is described as a first conductive line layer C12.

  When the first conductive line C1 is wound three times from the radially outer side to the inner side and then wound three times from the inner side to the outer side, the winding machine is regulated by the annular portion 531 and outside the first conductive line layer C12, The first conducting wire C1 is further wound three times in order from the radially outer side to the inner side. And it winds around the surface of outer side coil winding part 532A-1 so that three 1st conduction | electrical_connection lines C1 may be further arranged in the outer side of 1st conduction | electrical_connection line layer C12. The outermost first conductive line C1 that appears to be lined up is described as a first conductive line layer C13.

  As described above, the block B is disposed on the front surface and the rear surface of the inner coil winding portion 532A-2, and the first conductive wire C1 is wound by the winding machine, thereby forming the outer coil winding portion 532A-1. Forms an outer coil (first coil) of 3 turns × 3 layers.

  After winding the first conducting wire C1, the block B is removed from the inner coil winding portion 532A-2. At this time, the first conductive wire C1 wound around the outer coil winding portion 532A-1 may be temporarily fixed so as not to collapse.

  After removing the block B, the winding machine winds the second conductive wire C2 around the inner coil winding portion 532A-2. The winding machine first winds the second conductive wire C2 three times on the surface of the inner coil winding portion 532A-2 in order from the radially outer side to the inner side. At this time, a second conductive line layer C21 that appears to have three second conductive lines C2 arranged is formed on the surface of the inner coil winding portion 532A-2. When the winding is performed three times, the winding machine is restricted by the stopper portion 532B, and the second conductive wire C2 is wound three times on the outer side of the second conductive wire layer C21 in order from the radially inner side to the outer side. At this time, the second conductive line layer C22 is formed on the surface of the inner coil winding portion 532A-2.

  When the second conductive wire C2 is wound three times from the radially outer side to the inner side and then wound three times from the inner side to the outer side, the winding machine has the first conductive wire C1 wound around the outer coil winding portion 532A-1. The second conductive wire C2 is wound three more times in order from the outer side in the radial direction to the inner side on the outer side of the second conductive line layer C22. And on the surface of inner coil winding part 532A-2, the 2nd conduction line layer C23 is further formed in the outer side of the 2nd conduction line layer C22.

  As described above, the layer of the first conductive wire C1 wound around the outer coil winding portion 532A-1 plays a role similar to that of the block B, and the inner coil winding portion 532A-2 includes 3 turns × 3. An inner coil (second coil) of the layer is formed.

  By winding in this way, the coil length of the first conducting wire C1 of the outer coil and the coil length of the second conducting wire C2 of the inner coil are substantially the same. That is, the outer coil and the inner coil have the same wire diameter and coil length, and have substantially the same resistance value.

  Here, in the coil winding part 532A of each tooth part 532, as described with reference numerals U, V, and W in FIG. It is wound. At this time, coils of the same phase are wound around two, that is, a pair of teeth portions 532 that are opposed to each other in the radial direction. If these two teeth parts 532 are described as a tooth group, the six teeth parts 532 constitute a three-phase tooth group of a U phase, a V phase, and a W phase. For example, the two tooth portions 532 shown in FIG. 8 constitute one tooth set. For convenience of explanation, the left tooth portion 532 in FIG. 8 is referred to as a first tooth portion 532, and the right tooth portion 532 is referred to as a second tooth portion 532. Further, it is assumed that a U-phase coil is wound around these teeth portions 532. The V phase and the W phase are the same as in the case of the U phase, and thus description thereof will be omitted as appropriate.

  In FIG. 8, the U-phase first conductive wire C <b> 1 is wound around the outer coil winding portion 532 </ b> A- 1 to form the U-phase outer coil in the left first tooth portion 532. Further, the U-phase second conducting wire C2 is wound around the inner coil winding portion 532A-2, and a U-phase inner coil is formed.

  Similarly, a U-phase conductive wire (not shown) is wound around the outer coil winding portion 532A′-1 to form a U-phase outer coil in the second tooth portion 532 on the right side. Further, a U-phase conductive wire (not shown) is wound around the inner coil winding portion 532A′-2 to form a U-phase inner coil.

  These four U-phase coils are all wound around the winding machine as described above, so that the coil lengths are all substantially the same. Then, the connection form of these four coils is demonstrated.

  The outer coil wound around the outer coil winding portion 532A-1 of the first tooth portion 532 is connected in series with the inner coil wound around the inner coil winding portion 532A'-2 of the second tooth portion 532. . That is, the outer coil of the first tooth portion 532 and the inner coil of the second tooth portion 532 are connected via the jumper wire. The two connected coils constitute a first U-phase coil section.

  That is, the procedure for winding the conductive wire (coil) C around the coil winding portion 532A is as follows. First, the block B is disposed on the inner coil winding portion 532A-2 of the first tooth portion 532 and the outer coil winding portion 532A′-1 of the second tooth portion 532. Thereafter, one of the outer coil winding portion 532A-1 of the first tooth portion 532 and the inner coil winding portion 532A'-2 of the second tooth portion 532, for example, the outer coil winding portion 532A-1, is wound by a winding machine. The first conductive line C1 is wound. Thereafter, the first conductive wire C1 is passed along the annular portion 531 to the other coil winding portion. The first conductive line C1 passed along the annular portion 531 corresponds to a jumper line. And a 1st U-phase coil part is comprised by winding the 1st conduction wire C1 to the other coil winding part, for example, inner side coil winding part 532A'-2. In other words, a set of coil parts is formed by winding one conductive wire C around one coil winding part and then winding it around the other coil winding part.

  After removing the block B, similarly, the inner coil wound around the inner coil winding portion 532A-2 of the first tooth portion 532 and the outer coil winding portion 532A'-1 of the second tooth portion 532 are wound. The outer coil to be rotated is connected in series. That is, by the winding machine, the second conductive wire C2 is connected to one of the inner coil winding portion 532A-2 of the first tooth portion 532 and the outer coil winding portion 532A'-1 of the second tooth portion 532, for example, the inner coil. After being wound around winding portion 532A-2, it is passed along annular portion 531 and wound around the other coil winding portion, for example, outer coil winding portion 532A′-1. In this way, the inner coil of the first tooth portion 532 and the outer coil of the second tooth portion 532 are connected via the jumper wire. The two connected coils constitute a second U-phase coil unit.

  FIGS. 11 to 13 are a front view, a side view, and a plan view showing the stator 53 and the crossover wires in the first embodiment. 11 to 13, for the sake of explanation, only the connecting wire portion of the conducting wire C is shown, and the conducting wire C wound around each tooth portion 532 is not shown. The front outer peripheral surface of the annular portion 531 of the stator 53 is covered with an insulator, and six ribs 531A for winding a jumper wire are provided. The outer coil and the inner coil wound around the outer coil winding portion 532A-1 of the first tooth portion 532 and the inner coil winding portion 532A'-2 of the second tooth portion 532 are shown in FIGS. As described above, the conductive line C is connected by a jumper line arranged along the front outer peripheral surface of the annular portion 531. The connecting wire makes a half turn around the circumferential surface of the annular portion 531 so as to connect the first tooth portion 532 and the second tooth portion 532 facing each other.

  As described above, the first U-phase coil part and the second U-phase coil part are connected in series via the jumper wires arranged along the circumferential surface of the annular part 531 between the outer coil and the inner coil of the opposing teeth part. In this case, the length of the connecting wire connecting the two coils is a length that circulates around the outer peripheral surface of the annular portion 531 and is substantially the same. That is, the first U-phase coil portion and the second U-phase coil portion are configured as coil portions having the same resistance value and the same wire diameter and coil length, respectively. Further, the outer coil and the inner coil are arranged so as not to overlap in the axial direction (front-rear direction). The first U-phase coil part is a coil wound around the outer coil winding part 532A-1 of the first tooth part 532 and the outer coil winding part 532A'-1 of the second tooth part 532, and the second U-phase coil part The coil may be wound around the inner coil winding portion 532A-2 of the first tooth portion 532 and the outer coil winding portion 532A′-2 of the second tooth portion 532. That is, you may comprise a 1st U-phase coil part and a 2nd U-phase coil part by connecting the outer side coils of an opposing teeth part, and connecting inner side coils.

  In the other tooth groups, that is, the V-phase tooth group and the W-phase tooth group, the resistance value is equal by connecting the outer coil and the inner coil of the opposing teeth part in series as in the U-phase tooth group. A first V-phase coil unit, a second V-phase coil unit, a first W-phase coil unit, and a second W-phase coil unit are configured.

  Moreover, the coil part in the same phase is comprised so that series connection and parallel connection are respectively possible. Here, the connection state of the twelve coils in the motor 5 will be described with reference to FIGS. 4 and 5. 4 and 5 are circuit diagrams showing a connection state of two U-phase coil units, two V-phase coil units, and two W-phase coil units in the motor 5. FIG. 4 shows a state where the coil portions are connected in series in each phase, and FIG. 5 shows a state where the coil portions are connected in parallel in each phase.

  As shown in FIGS. 4 and 5, the stator 53 includes a star-connected three-phase coil section, that is, a U-phase coil section 54, a V-phase coil section 55, and a W-phase coil section 56. Specifically, the U-phase neutral point connection point 54a of the U-phase coil unit 54, the V-phase neutral point connection point 55a of the V-phase coil unit, and the W-phase neutral point connection point 56a of the W-phase coil unit are respectively Are connected to the neutral point 5a. The U-phase power supply side connection point 54 b of the U-phase coil unit 54, the V-phase power supply side connection point 55 b of the V-phase coil unit 55, and the W-phase power supply side connection point 56 b of the W-phase coil unit 56 are respectively connected to the control board 81. Connected to the inverter circuit.

  The U-phase coil unit 54 includes a first U-phase coil unit 54A and a second U-phase coil unit 54B. First U-phase coil portion 54A and second U-phase coil portion 54B are connected via switching contact 72A and switching contact 72B of relay 72. In the U-phase coil unit 54, the first U-phase coil unit 54A corresponds to the first coil, and the second U-phase coil unit 54B corresponds to the second coil.

  The first U-phase coil unit 54A includes two first U-phase coils 54A-1 and 54A-2. The first U-phase coil 54A-1 is an outer coil wound around the outer coil winding portion 532A-1 of the first tooth portion 532 shown in FIG. 8, and the first U-phase coil 54A-2 is the second tooth portion. 532 is an inner coil wound around the inner coil winding portion 532A′-2. The two first U-phase coils 54A-1 and 54A-2 have the same number of turns, and are connected in series via the jumper wire 54A-3. 54 A of 1st U-phase coil parts are comprised by winding the 1st conduction | electrical_connection line C1 around the 1st teeth part 532 and the 2nd teeth part 532 which are a pair of teeth part 532 which opposes. The first U-phase coils 54A-1 and 54A-2 correspond to a pair of first winding portions.

  Of the first U-phase coil portion 54A, the end portion on the first U-phase coil 54A-1 side which is an outer coil is connected to the U-phase power supply side connection point 54b via the connection line 54D-1. Further, the end portion on the first U-phase coil 54 </ b> A- 2 side, which is an inner coil, can be connected to either the connection line 54 </ b> D- 2 or the connection line 54 </ b> C via the switching contact 72 </ b> A of the relay 72. The connection line 54D-1 and the connection line 54D-2 correspond to a pair of first connection parts, and the connection line 54C corresponds to a third connection part. The switching contact 72A of the relay 72 corresponds to the first switching unit.

  Similarly, the second U-phase coil unit 54B includes two second U-phase coils 54B-1 and 54B-2. The second U-phase coil 54B-1 is an inner coil wound around the inner coil winding portion 532A-2 of the first tooth portion 532 shown in FIG. 8, and the second U-phase coil 54B-2 is the second tooth portion. 532 is an outer coil wound around the outer coil winding portion 532A′-1. The two second U-phase coils 54B-1 and 54B-2 have the same number of turns, and are connected in series via the jumper wire 54B-3. The second U-phase coil unit 54B is configured by winding one second conductive wire C2 around a first tooth portion 532 and a second tooth portion 532 which are a pair of teeth portions 532 facing each other. Second U-phase coils 54B-1 and 54B-2 correspond to a pair of second winding portions. Here, the length of the connecting wire 54B-3 is the same as the length of the connecting wire 54A-3 in the first U-phase coil portion 54A. That is, the coils are connected so that the first U-phase coil portion 54A and the second U-phase coil portion 54B have the same coil length.

  Of the second U-phase coil portion 54B, the end on the second U-phase coil 54B-1 side that is an inner coil can be connected to either the connection line 54E-1 or the connection line 54C via the switching contact 72B of the relay 72. It has become. Further, the end portion on the second U-phase coil 54B-2 side which is an outer coil is connected to a U-phase neutral point connection point 54a via a connection line 54E-2. In U-phase coil portion 54, the length of connection line 54D-1 is the same as the length of connection line 54E-2. The length of the connection line 54D-2 is the same as the length of the connection line 54E-1. The connection line 54E-1 and the connection line 54E-2 correspond to a pair of second connection parts, and the switching contact 72B of the relay 72 corresponds to a second switching part.

  Similarly, the V-phase coil unit 55 includes a first V-phase coil unit 55A and a second V-phase coil unit 55B. First V-phase coil portion 55A and second V-phase coil portion 55B are connected via switching contact 72A and switching contact 72B of relay 72. In the V-phase coil unit 55, the first V-phase coil unit 55A corresponds to the first coil, and the second V-phase coil unit 55B corresponds to the second coil.

  First V-phase coil unit 55A includes two first V-phase coils 55A-1 and 55A-2. The first V-phase coils 55A-1 and 55A-2 have the same number of turns, and are connected in series via a jumper wire 55A-3. The first V-phase coil portion 55A is configured by winding one first conductive wire C1 around a pair of opposing teeth portions 532. First V-phase coils 55A-1 and 55A-2 correspond to a pair of first winding portions.

  Of the first V-phase coil portion 55A, the end portion on the first V-phase coil 55A-1 side is connected to the V-phase power supply side connection point 55b via the connection line 55D-1. Further, the end portion on the first V-phase coil 55A-2 side can be connected to either the connection line 55D-2 or the connection line 55C via the switching contact 72A of the relay 72. The connection line 55D-1 and the connection line 55D-2 correspond to a pair of first connection parts, and the connection line 55C corresponds to a third connection part. The switching contact 72A of the relay 72 corresponds to the first switching unit.

  Similarly, the second V-phase coil section 55B includes two second V-phase coils 55B-1 and 55B-2. The two second V-phase coils 55B-1 and 55B-2 have the same number of turns, and are connected in series via the jumper wire 55B-3. The second V-phase coil unit 55B is configured by winding one second conducting wire C2 around a first tooth portion 532 and a second tooth portion 532 that are a pair of teeth portions 532 facing each other. Second V-phase coils 55B-1 and 55B-2 correspond to a pair of second winding portions. Here, the length of the connecting wire 55B-3 is the same as the length of the connecting wire 55A-3 in the first V-phase coil portion 55A. That is, the coils are connected so that the coil lengths of the first V-phase coil unit 55A and the second V-phase coil unit 55B are equal.

  Of the second V-phase coil section 55B, the end on the second V-phase coil 55B-1 side can be connected to either the connection line 55E-1 or the connection line 55C via the switching contact 72B of the relay 72. . Further, the end portion on the second V-phase coil 55B-2 side is connected to a V-phase neutral point connection point 55a via a connection line 55E-2. In the V-phase coil section 55, the length of the connection line 55D-1 is the same as the length of the connection line 55E-2. Further, the length of the connection line 55D-2 is the same as the length of the connection line 55E-1. The connection line 55E-1 and the connection line 55E-2 correspond to a pair of second connection portions, and the switching contact 72B of the relay 72 corresponds to a second switching portion.

  Similarly, the W-phase coil unit 56 includes a first W-phase coil unit 56A and a second W-phase coil unit 56B. First W-phase coil section 56A and second W-phase coil section 56B are connected via switching contact 72A and switching contact 72B of relay 72. In the W-phase coil unit 56, the first W-phase coil unit 56A corresponds to the first coil, and the second W-phase coil unit 56B corresponds to the second coil.

  First W-phase coil section 56A includes two first W-phase coils 56A-1 and 56A-2. The first W-phase coils 56A-1 and 56A-2 have the same number of turns, and are connected in series via the jumper wire 56A-3. First W-phase coil portion 56A is configured by winding one first conductive wire C1 around a pair of opposing teeth portions 532. First W-phase coils 56A-1 and 56A-2 correspond to a pair of first winding portions.

  Of the first W-phase coil portion 56A, the end portion on the first W-phase coil 56A-1 side is connected to the W-phase power supply side connection point 56b via the connection line 56D-1. Further, the end portion on the first W-phase coil 56 </ b> A- 2 side can be connected to either the connection line 56 </ b> D- 2 or the connection line 56 </ b> C via the switching contact 72 </ b> A of the relay 72. The connection line 56D-1 and the connection line 56D-2 correspond to a pair of first connection portions, and the connection line 56C corresponds to a third connection portion. The switching contact 72A of the relay 72 corresponds to the first switching unit.

  Similarly, the second W-phase coil unit 56B includes two second W-phase coils 56B-1 and 56B-2. The two second W-phase coils 56B-1 and 56B-2 have the same number of turns and are connected in series via the jumper wire 56B-3. The second W-phase coil unit 56 </ b> B is configured by winding one second conductive wire C <b> 2 around the first tooth portion 532 and the second tooth portion 532 that are a pair of teeth portions 532 facing each other. Second W-phase coils 56B-1 and 56B-2 correspond to a pair of second winding portions. Here, the length of the connecting wire 56B-3 is the same as the length of the connecting wire 56A-3 in the first W-phase coil section 56A. That is, the coils are connected so that the first W-phase coil portion 56A and the second W-phase coil portion 56B have the same coil length.

  Of the second W-phase coil portion 56B, the end portion on the second W-phase coil 56B-1 side can be connected to either the connection line 56E-1 or the connection line 56C via the switching contact 72B of the relay 72. . Further, the end portion on the second W-phase coil 56B-2 side is connected to a W-phase neutral point connection point 56a via a connection line 56E-2. In W phase coil section 56, the length of connection line 56D-1 is the same as the length of connection line 56E-2. Further, the length of the connection line 56D-2 is the same as the length of the connection line 56E-1. The connection line 56E-1 and the connection line 56E-2 correspond to a pair of second connection parts, and the switching contact 72B of the relay 72 corresponds to a second switching part.

  Each switching contact 72A, 72B switches the connection state of the two coil units in each phase based on a signal from a control unit (not shown) (such as a microcomputer mounted on the control board 81). For example, when the first signal (ON signal) is input from the control unit, as shown in FIG. 4, the switching contact 72A connects the first U-phase coil unit 54A to the connection line 54C, and the switching contact 72B The 2U phase coil portion 54B is connected to the connection line 54C. As a result, the U-phase coil unit 54 is in a serial connection state in which the first U-phase coil unit 54A and the second U-phase coil unit 54B are connected in series via the connection line 54C. Similarly, the V-phase coil unit 55 is in a serial connection state in which the first V-phase coil unit 55A and the second V-phase coil unit 55B are connected in series to each other via the connection line 55C, and the W-phase coil unit 56 is connected to the first W-phase coil unit 55B. The coil unit 56A and the second W-phase coil unit 56B are connected in series with each other via the connection line 56C.

  On the other hand, when the second signal (OFF signal) is input from the control unit, as shown in FIG. 5, the switching contact 72A connects the first U-phase coil unit 54A to the connection line 54D-2, and the switching contact 72B. Connects the second U-phase coil portion 54B to the connection line 54E-1. Thereby, in the U-phase coil unit 54, the first U-phase coil unit 54A and the second U-phase coil unit 54B are connected in parallel to each other via the connection lines 54D-1 and 54D-2 and the connection lines 54E-1 and 54E-2. Will be connected in parallel. Similarly, in the V-phase coil unit 55, a first V-phase coil unit 55A and a second V-phase coil unit 55B are connected in parallel to each other via connection lines 55D-1, 55D-2 and connection lines 55E-1, 55E-2. In the W-phase coil unit 56, the first W-phase coil unit 56A and the second W-phase coil unit 56B are connected to each other via connection lines 56D-1, 56D-2 and connection lines 56E-1, 56E-2. It becomes the parallel connection state connected in parallel. That is, the two coil portions in the same phase are configured to be switchable between the serial connection state and the parallel connection state by the switching contacts 72A and 72B of the relay 72.

  The control unit switches the coil connection method in the same phase between serial connection and parallel connection in accordance with the voltage of the drive source, and when driving with the commercial power supply P (AC power supply), By bringing the voltage applied to both ends close to the voltage applied to both ends of one coil when driven by the battery pack S (DC power supply), fluctuations in motor characteristics between the two drive power supplies are suppressed. . Specifically, when the motor 5 is driven by the commercial power source P, the first coil unit and the second coil unit in each phase of the U-phase coil unit 54, the V-phase coil unit 55, and the W-phase coil unit 56 are connected in series. When the motor 5 is driven by the battery pack S, the first coil portion and the second coil portion in each phase of the U-phase coil portion 54, the V-phase coil portion 55, and the W-phase coil portion 56 are connected in parallel. State. Here, the first coil portion refers to the first U-phase coil portion 54A, the first V-phase coil portion 55A, and the first W-phase coil portion 56A, and the second coil portion refers to the second U-phase coil portion 54B and the second V-phase. The coil part 55B and the 2nd W phase coil part 56B are meant.

  As described above, according to the desktop circular saw 1 according to the present embodiment, the outer coil winding portion having the same length L in the radial direction and the same surface area is provided on each of the teeth portions 532 of the stator 53. 532A-1 and the inner coil winding portion 532A-2 are defined, and coils having the same number of turns are wound around the coil winding portions 532A-1 and 532A-2. At this time, in each coil winding part 532A-1, 532A-2, the conductive wire layer in which three conductive wires C are arranged in the radial direction is arranged so as to overlap three layers in the axial direction. The outer coil wound around the winding part 532A-1 and the inner coil wound around the inner coil winding part 532A-2 have the same coil length and the same resistance value. The outer coil is connected in series to the inner coil wound around the inner coil winding portion 532A-2 of the opposing teeth portion 532 via a jumper, and is one of the U phase, the V phase, and the W phase. The first coil portion is configured, and the inner coil is connected in series to the outer coil wound around the outer coil winding portion 532A-1 of the opposing tooth portion 532 via a jumper wire, and is the second coil of the same phase Parts. At this time, since the connecting wire of the first coil portion and the connecting wire of the second coil portion have the same length, the first coil portion and the second coil portion have the same coil length and the same resistance value. It becomes. Furthermore, the length of the connection line for connecting the first coil part between the neutral point connection point and the power supply side connection point, and for connecting the second coil part between the neutral point connection point and the power supply side connection point The lengths of the connection lines are the same, and the relays 72 having the same internal resistance value are connected to the first coil portion and the second coil portion one by one. Therefore, even when the first coil portion and the second coil portion in the same phase are connected in parallel via the connection line and the relay 72, reflux based on the difference in resistance value does not occur, and a decrease in output is prevented. Specifically, in the case of the conventional configuration, the difference in resistance value between the coils connected in parallel is 18%, and the output is about 20% (about 80 W). According to the present invention, since the two coil lengths can be made substantially equal, the difference between the resistance value and the output can be made as close to zero as possible although there is variation.

  In the above-described embodiment, when the conductive wire C is wound around the tooth portion 532, the block B is first disposed in the inner coil winding portion 532A-2 and is electrically connected to the outer coil winding portion 532A-1. Although winding of the wire C was implemented, this invention is not limited to this. First, the block B is arranged in the outer coil winding portion 532A-1, the inner conductive wire C2 is wound around the inner coil winding portion 532A-2, and then the conductive wire is connected to the outer coil winding portion 532A-1. Similarly, when C is wound, two coils having the same coil length can be wound around the tooth portion 532. Further, the winding of the conductive wire C is started from the radially outer side to the inner side, but may be started from the radially inner side to the outer side.

  In the above-described embodiment, two coils are wound around the tooth portion, but the present invention is not limited to this. For example, when N coils (N is an integer of 3 or more) are wound around the tooth portion 532, the coil winding portion 532A is equally divided into N in the radial direction, and the first coil winding portion 532A-1 from the outside, 2nd coil winding part 532A-2 ... It prescribes | regulates as Nth coil winding part 532A-N. And what is necessary is just to wind the conducting wire C by the same number of turns to each coil winding part one by one. At this time, a block may be disposed so as to cover the front surface and the rear surface of the coil winding portion where the conductive wire C is not wound, and the conductive wire may be wound by a winding machine. Then, it is connected in series with the coil of the opposing teeth portion in a one-to-one relationship. At this time, the coil of the nth coil winding portion from the radially outer side of the first tooth portion 532 and the nth coil from the radially inner side of the second tooth portion 532, that is, n is an integer from 1 to N, that is, A coil of the (N−n + 1) th coil winding portion from the radially outer side is connected by a jumper wire. And what is necessary is just to be able to connect the N coil part comprised in this way in parallel connection and series connection.

  In the above-described embodiment, six tooth portions are provided, but the present invention is not limited to this. It is also possible to provide more than six teeth or fewer than six teeth. For example, when three tooth portions are provided, coils wound around the respective tooth portions are connected in parallel to form a one-phase coil portion. And a three-phase coil part will be star-connected.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the shape of the teeth portion of the stator is different from that of the first embodiment. Note that the same members and configurations as those of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different configurations are described.

  FIG. 14 is a front view showing the configuration of the stator 153 in the tabletop circular saw motor according to the second embodiment of the present invention, and FIG. 15 is a sectional view taken along the line XV-XV in FIG. FIG. 16 is a view showing a coil winding portion in the second embodiment, and FIG. 17 is a partially enlarged view of FIG.

  As shown in FIG. 14, the stator 153 includes an annular portion 531 and six teeth portions 1532. The six teeth portions 1532 are arranged on the inner peripheral surface of the annular portion 531 at intervals of 60 ° in the circumferential direction. Each tooth portion 1532 has a coil winding portion 1532A and a stopper portion 532B, and the surface thereof is covered with an insulator.

  The coil winding portion 1532 </ b> A is a portion having a rectangular cross section and a prismatic shape whose axial dimension is shorter than that of the annular portion 531, and protrudes radially inward from the inner peripheral surface of the annular portion 531. Further, as shown in FIG. 15, a rib 1532D is erected on the front surface (front surface) of the coil winding portion 1532A so as to protrude forward. Similarly, a rib 1532D is also erected on the rear surface of the coil winding portion 1532A so as to protrude forward.

  As shown in FIG. 15, the rib 1532D is provided at a position that equally divides the length of the coil winding portion 1532A in the radial direction, and the coil winding portion 1532A is connected to the outer coil winding portion 1532A-1 and the inner coil winding. Dividing into turning parts 1532A. The outer coil winding portion 1532A-1 is located on the annular portion 531 side, that is, on the radially outer side, and the inner coil winding portion 1532A-2 is located on the stopper portion 532B side, that is, on the radially inner side. The outer coil winding portion 1532A-1 and the inner coil winding portion 1532A-2 are defined by the ribs 1532D so that the radial length L and the surface area are the same. In the present embodiment, the length L in the radial direction of the outer coil winding portion 1532A-1 and the inner coil winding portion 1532A-2 is approximately three times the wire diameter φ of the conducting wire C. It is prescribed as follows.

  In each tooth portion 1532, a conductive wire C is wound around the outer coil winding portion 1532 </ b> A- 1 to form an outer coil. Further, a conductive wire C different from that of the outer coil winding portion 1532A-1 is wound around the inner coil winding portion 1532A-2 to form an inner coil. In this embodiment, each of the conductive wires C wound around the outer coil winding portion 1532A-1 and the inner coil winding portion 1532A-2 has the same wire diameter φ, and the number of turns is nine. The coil is formed by being wound around the portion 1532A.

  Next, a method for winding the conductive wire C around each coil winding portion 1532A will be described. Winding of the conductive wire C around the coil winding portion 1532A is performed using a winding machine. In the motor of the present embodiment, the coil winding portion 1532A of the stator 153 is provided with the rib 1532D, and therefore, unlike the first embodiment, the block B need not be arranged.

  The winding machine winds the first conductive wire C1 three times on the surface of one of the coil winding portions 1532A, for example, the outer coil winding portion 1532A-1, in order from the radially outer side to the inner side. Thereby, the first conductive line layer C11 is formed on the surface of the outer coil winding portion 1532A-1.

  When the first conductive line C1 is wound three times and the first conductive line layer C11 is formed, the winding machine is regulated by the rib 1532D, and outside the first conductive line layer C11 from the radially inner side to the outer side. In sequence, the first conductive line C1 is wound three times. As a result, the first conductive line layer C12 is formed outside the first conductive line layer C11.

  When the first conductive line C1 is wound three times from the radially outer side to the inner side and then wound three times from the inner side to the outer side, the winding machine is regulated by the annular portion 531 and outside the first conductive line layer C12, The first conducting wire C1 is further wound three times in order from the radially outer side to the inner side. As a result, a first conductive line layer C13 is further formed outside the first conductive line layer C12.

  As described above, even if the block B is not arranged, the outer coil winding portion 1532A-1 is formed with an outer coil of 3 turns × 3 layers by winding the first conductive wire C1 with a winding machine. Is done.

  Subsequently, as shown in FIGS. 11 to 13, the first conductive line C <b> 1 is passed along the circumferential surface of the annular portion 531 and wound around the inner coil winding portion 1532 </ b> A′- 2 of the opposing teeth portion 1532. Turned. The first conductive line C1 may be wound around the outer coil winding portion 1532A-1 after being wound around the inner coil winding portion 1532A′-2.

  The winding machine winds the second conductive wire C2 around the inner coil winding portion 1532A-2. The winding machine first winds the second conductive wire C2 three times on the surface of the inner coil winding portion 1532A-2 in order from the radially outer side to the inner side. Thereby, the 2nd conduction wire layer C21 is formed in the surface of inner coil winding part 1532A-2.

  When the second conductive line C2 is wound three times and the second conductive line layer C21 is formed, the winding machine is restricted by the stopper portion 532B, and the outer side of the second conductive line layer C21 is moved from the radially inner side. The second conductive line C2 is wound three times in order outward. As a result, the second conductive line layer C22 is formed outside the second conductive line layer C21.

  When the second conductive wire C2 is wound three times from the radially outer side to the inner side and then wound three times from the inner side to the outer side, the winding machine is restricted by the rib 1532D, and the outer diameter of the second conductive wire layer C22 The second conductive line C2 is further wound three times in order from the outer side to the inner side. As a result, a second conductive line layer C23 is further formed outside the second conductive line layer C22.

  As described above, by winding the second conductive wire C2 with a winding machine, an inner coil of 3 turns × 3 layers is formed in the inner coil winding portion 1532A-2.

  Subsequently, as shown in FIGS. 11 to 13, the second conductive line C <b> 2 is passed along the peripheral surface of the annular portion 531 and wound around the outer coil winding portion 1532 </ b> A′- 1 of the opposing teeth portion 1532. Turned. The second conductive line C2 may be wound around the inner coil winding portion 1532A-2 after being wound around the outer coil winding portion 1532A′-1.

  By winding in this way, the coil length of the conductive wire C of the outer coil and the coil length of the conductive wire C of the inner coil are substantially the same. That is, the outer coil and the inner coil have the same wire diameter and coil length, and have substantially the same resistance value. Since the connection form of the 12 coils is the same as that of the first embodiment, the description thereof is omitted.

  As described above, according to the tabletop circular saw motor according to the present embodiment, each tooth portion 1532 of the stator 153 is provided with the rib 1532D, and the rib 1532D has the same length L in the radial direction. In addition, since the outer coil winding portion 1532A-1 and the inner coil winding portion 1532A-2 having the same surface area are defined, each coil winding portion 1532A-1, only using a winding machine, without using a block or the like. A coil having the same coil length can be wound around 1532A-2. Therefore, it is possible to make the resistance values of the coils connected in parallel to each other substantially the same, and it is possible to prevent a decrease in output without increasing the size of the motor and the desk circular saw.

  In the above-described embodiment, the winding of the conductive wire C is started from the radially outer side to the inner side, but may be started from the radially inner side to the outer side. In the above-described embodiment, two coils are wound around the tooth portion 1532. However, the present invention is not limited to this. As described above, it is possible to connect three or more coil portions in parallel and in series by winding three or more coils. Similarly, the number of teeth portions is not limited to six.

  In addition, the coil winding portion is divided into two in the radial direction (outer coil winding portion and inner coil winding portion) to wind two coils, but if the two coil lengths can be made equal, The present invention is not limited to the above-described embodiment. For example, two coils may be wound as shown in FIGS.

  FIG. 18 is a partially enlarged view showing a coil winding portion in the first modification. In the first modified example, as shown in FIG. 18, the first conducting wire C1 and the second conducting wire C2 are alternately wound along the radial direction of the coil winding portion 532A. That is, in the pair of teeth portions 532 facing each other, the first conduction line C1, the second conduction line C2, the first conduction line C1,... It arrange | positions in order of the 2nd conduction line C2. In the other teeth portion 532 of the pair of teeth portions 532, the second conductive lines C2, the first conductive lines C1, the second conductive lines C2,... Arranged in the order of one conduction line C1. By arranging in this way, the first coil formed by the first conduction line C1 and the second coil formed by the second conduction line C2 have substantially the same coil length and resistance value. Also in this case, for example, the first conductive line C1 and the second conductive line C2 are wound three times in the radial direction and the front-rear direction of the annular portion 531 respectively, so the number of turns 9 is equal. In addition, this modification is a case where the winding of the conducting wire C around the teeth part 532 can be performed two by two with a winding machine.

  Moreover, FIG. 19 is the elements on larger scale which show the winding part of the coil in a 2nd modification. In the second modified example, as shown in FIG. 19, in one pair of teeth 532 facing each other, in one of the teeth 532, first, on the surface of the coil winding portion 532A, radially inward (stopper portion 532B side). The first conductive line C1 is wound six times in order from the outer side (annular part 531 side) to the first conductive line layer C11 of the first layer. Next, the first conductive line C1 is wound three times in order from the radially outer side to the inner side on the outer side of the first conductive line layer C11, and the second first conductive line layer C12 is disposed. That is, the first conductive wire C1 is wound around the entire area of the first layer in the coil winding portion 532A and the half region from the second-layer annular portion 531 side. Then, the second conductive line C2 is wound three times in order from the radially outer side to the inner side alongside the first conductive line layer C12 of the second layer on the outer side of the first conductive line layer C11 of the first layer. The second conductive line layer C22 is disposed. Next, the second conductive line C2 is wound six times around the second conductive line layer C22 and the first conductive line layer C12 in the second layer in order from the radially inner side to the outer side, and the second conductive line layer in the third layer is wound. The line layer C23 is disposed. That is, the second conductive wire C2 is wound around the remaining half area of the second layer and the entire area of the third layer in the coil winding portion 532A. In addition, the first layer of the first conductive line C1 may be wound in the order from the radially outer side to the inner side, and the second layer may be wound in the order from the inner side to the outer side. Then, the second layer of the second conductive line C2 may be wound in the order from the inside to the outside, and the third layer may be wound in the order from the outside to the inside. That is, the winding start of the conducting wire may be either on the outside or on the inside.

  In the other teeth portion 532 of the pair of teeth portions 532, the second conductive wire C2 is connected to the entire area of the first layer and the second layer of the coil winding portion 532A, contrary to the one teeth portion 532 (FIG. 19). It winds from the part 531 side to the area | region of a half length. Then, the first conductive wire C1 is wound around the remaining half of the second layer and the entire third layer of the coil winding portion 532A. Accordingly, the first coil formed by winding the first conductive line C1 around the pair of teeth portions 532 and the first coil formed by winding the second conductive line C2 around the pair of teeth portions 532. With the second coil, the number of turns 9 is equal, and the coil length and resistance value are also substantially equal. This modification is a case where the conductive wire C is wound around the teeth portion 532 manually.

  Further, in each of the above-described embodiments and the first and second modified examples, the arrangement of the coil portion wound around the coil winding portion of each tooth portion is devised so as to match the coil length and the resistance value. The first coil and the second coil are adjusted by adjusting the lengths of portions other than the coil portion (winding portion) wound around the coil winding portion, for example, the connecting portion and the crossover portion. These lengths and resistance values may be matched. Hereinafter, a third modification and a fourth modification will be described.

  FIG. 20 is a conceptual diagram illustrating the connection state of the coils in the third modification. In the third modification, the lengths and resistance values of the two coils are made equal by adjusting the lengths of the connection lines connecting the first coil part and the second coil part in each phase. .

  As in the prior art, when the first conductive line C1 is wound inside the tooth portion 532 and then the second conductive line C2 is wound outside the first conductive line C1, the second conductive line wound outside. Since the coil length of the second coil formed by C2 is longer than the coil length of the first coil formed by the first conducting wire C1 wound inside, the coil length is set to two A difference Δl will occur. In the U-phase coil unit 254 of the third modification shown in FIG. 20, after the second U-phase coil unit 54B is wound inside the teeth unit 532, the first U-phase coil unit 54A is replaced with the second U-phase coil unit 54B. Therefore, the coil length of the first U-phase coil portion 54A is longer than the coil length of the second U-phase coil portion 54B.

  However, as shown in FIG. 20, the length of the connection line 254E-2 that connects the second U-phase coil unit 254B to the U-phase neutral point connection point, and the first U-phase coil unit 54A is connected to the U-phase power supply side connection point. The length and resistance value of the coil from the U-phase neutral point connection point 54a to the U-phase power supply side connection point 54b by making the coil length difference Δl longer than the length of the connection line 54D-1 connected to 54b. Can be made substantially the same on the first U-phase coil portion 54A side and the second U-phase coil portion 54B side. Similarly, also in the V-phase coil unit 255 and the W-phase coil unit 256, the lengths of the connection line 255E-2 and the connection line 256E-2 are longer than the lengths of the connection line 55D-1 and the connection line 56D-1. Thus, the length and resistance value of the coil from the neutral point connection point to the power supply side connection point in each phase can be made substantially the same on the first coil portion side and the second coil portion side. This configuration is effective when two coils are connected in parallel.

  21 and 22 are conceptual diagrams for explaining the connection state of the coils in the fourth modification. FIG. 21 shows a state where the first coil portion and the second coil portion are connected in series in each phase, and FIG. 22 shows a state where they are connected in parallel. FIGS. 23 to 25 are a front view, a side view, and a plan view showing the stator 53 and the crossover wires in the fourth modification. In the fourth modification, the lengths and resistance values of the first coil and the second coil are made equal by adjusting the length of the crossover. In FIG. 23 to FIG. 25, for the sake of explanation, only the connecting wire portion of the conducting wire C constituting each coil is shown, and the conducting wire C wound around each tooth portion 532 is not shown.

  In the fourth modification shown in FIGS. 21 and 22, after the first conductive line C1 is wound inside the tooth portion 532 to form the first coil portion, the second conductive wire C2 is the first coil. The second coil part is formed by being wound around the outside of the part. In this case, since the coil length of the second coil portion is longer than the coil length of the first coil portion, a difference Δl occurs between the two coil lengths. For example, in the U-phase coil unit 354, the coil lengths of the two second U-phase coils 54B-1 and 54B-2 included in the second U-phase coil unit 54B are the two first U-phases included in the first U-phase coil unit 354A. It is shorter than the coil length of the coils 54A-1 and 54A-2.

  However, the length of the connecting wire 354A-3 connecting the two first U-phase coils 54A-1 and 54A-2 in the first U-phase coil section 354A is different from the length of the two second U-phase coils 54B- in the second U-phase coil section 54B. The length of the first U-phase coil portion 354A and the length of the second U-phase coil portion 54B are substantially the same by making the coil length difference Δl longer than the length of the connecting wire 54B-3 connecting the 1 and 54B-2. It can be. Similarly, in the V-phase coil unit 355 and the W-phase coil unit 356, the lengths of the connecting wire 355A-3 and the connecting wire 356A-3 are made longer than the lengths of the connecting wire 55B-3 and the connecting wire 56B-3. Thereby, the length and resistance value of the 1st coil part in each phase can be made substantially the same as the length and resistance value of the 2nd coil part. This configuration is effective when two coils are connected in parallel.

  FIG. 26 is an explanatory diagram showing the arrangement of the crossover portion of the coil in the fourth modified example. Fig.26 (a) is a figure explaining arrangement | positioning of the crossover of a 1st coil part, and shows only the crossover part of the 1st coil part of each phase. Moreover, FIG.26 (b) is a figure explaining arrangement | positioning of the connecting wire of a 2nd coil part, and shows only the connecting wire part of the 2nd coil part of each phase.

  For example, the first conductive wire C1 having a wire diameter φ = 1.0 mm is wound around each of the pair of teeth portions 532 facing each other with the number of turns 9 on the stator 53 having an outer diameter of 55 mm and a longitudinal length of 25 mm. Subsequently, the case where the second conducting wire C2 having the same wire diameter φ = 1.0 mm is wound around the first conducting wire C1 by the number of turns 9 will be described as an example. In this case, the sum of only the coil lengths of the pair of coils wound around the teeth portion 532 by the first conductive line C1, that is, the two coils of the first coil portion, is 1626 mm. On the other hand, the sum of only one coil length of a pair of coils wound around the first coil portion by the second conductive line C2, that is, the two coil portions of the second coil portion is 1794 mm. The length difference Δl is 168 mm.

  At this time, the positions of the six ribs 531A provided on the front outer peripheral portion of the annular portion 531 of the stator 53 are adjusted so that the outer diameter (winding diameter) of the portion where the jumper wire is wound is 53 mm. When passing the first conductive line C1 serving as a connecting wire for the first coil portion from one of the pair of teeth portions 532 to the other, as shown by an arrow D in FIG. It is assumed that one and a half wraps around the front outer periphery. Further, when passing the second conductive line C2 serving as a connecting wire of the second coil portion from one of the pair of teeth portions 532 to the other, as shown by an arrow E in FIG. It is assumed that only a half circumference is wound around the front outer circumference of the. By arranging the connecting wire in this way, the wire length of the connecting wire portion of the first coil portion becomes one turn of the winding diameter, that is, 166 mm longer than the wire length of the connecting wire portion of the second coil portion. Due to the difference in the wire length of the crossover portion, the difference in coil length Δl = 168 mm can be substantially canceled out, and the first coil portion and the second coil portion have substantially the same length and resistance. . This configuration is effective when two coils are connected in parallel.

  27 and 28 are conceptual diagrams for explaining the connection state of the coils in the fifth modification. FIG. 27 shows a state where the first coil portion and the second coil portion are connected in series in each phase, and FIG. 28 shows a state where they are connected in parallel. FIG. 29 is a side view of the circular substrate 71 in the fifth modification. In the fifth modification, the resistance values of the first coil and the second coil are made equal by providing a resistance in the coil portion of each phase.

  In the fifth modification shown in FIGS. 27 to 29, the first conductive wire C1 of each phase is wound inside the tooth portion 532 to form the first coil portion, as in the fourth modification. After that, the second conductive line C2 is wound around the outside of the first coil part to form the second coil part. The lengths of the connecting wires connecting the two coils in each coil portion are all arranged to be substantially the same. That is, the coil length of the second coil portion is longer than the coil length of the first coil portion, and the resistance value of the first coil portion is smaller than the resistance value of the second coil portion. For example, in the U-phase coil unit 454, the resistance value of the first U-phase coil unit 54A is smaller than the resistance value of the second U-phase coil unit 54B.

  Therefore, in the fifth modification, as shown in FIGS. 27 and 28, a resistor 74 that can be connected in series is provided in the first coil portion of each phase. For example, in the U-phase coil unit 454, one end of the resistor 74 is connected to the U-phase neutral point connection point 54a, and the other end is the end of the first U-phase coil unit 54A on the first U-phase coil 54A-2 side. In addition, connection is possible via a switching contact 72A of the relay 72. When the difference between the resistance value of the first U-phase coil portion 54A and the resistance value of the second U-phase coil portion 54B is ΔΩ, the resistance value of the resistor 74 is the resistance value from the U-phase neutral point connection point 54a to the switching contact 72A. Is adjusted to a value obtained by adding the above-described resistance difference ΔΩ to the resistance value of the connection line 54E-1 connected to the second U-phase coil portion 54B.

  Similarly, in the V-phase coil unit 455, one end of the resistor 74 is connected to the V-phase neutral point connection point 55a, and the other end is the end of the first V-phase coil unit 55A on the first V-phase coil 55A-2 side. It is possible to connect to this part via a switching contact 72A of the relay 72. Further, in the W-phase coil unit 456, one end of the resistor 74 is connected to the W-phase neutral point connection point 56a, and the other end is an end of the first W-phase coil unit 56A on the first W-phase coil 56A-2 side. In addition, connection is possible via a switching contact 72A of the relay 72. These resistors 74 have similarly adjusted resistance values. That is, the three resistors 74 have the same resistance value.

  By arranging the resistor 74 having such a resistance value, the resistance value from the neutral point connection point to the power supply side connection point in each phase is substantially the same on the first coil portion side and the second coil portion side. It can be. Therefore, as shown in FIG. 28, even when the first coil portion and the second coil portion in the same phase are connected in parallel via the connection line and the relay 72, reflux based on the difference in resistance value does not occur, and the output Is prevented.

  As shown in FIG. 27, when the first coil portion and the second coil portion in the same phase are connected in series via a connection line, each resistor 74 is disposed outside the connection path. For example, in the U-phase coil unit 454, when the connection destination of the switching contact 72A and the switching contact 72B of the relay 72 is switched to the connection line 54C, the first U-phase coil unit 54A and the second U-phase connected in series via the connection line 54C. The end portion on the first U-phase coil portion 54A side of the coil portion 54B is connected to the U-phase power supply side connection point 54b via the connection line 54D-1, and the end portion on the second U-phase coil portion 54B side is connected to the connection line 54E-2. To the U-phase neutral point connection point 54a. Thereby, in the U-phase coil unit 454, the resistor 74 is disposed outside the serial connection path.

  Similarly, in the V-phase coil unit 455, when the connection destination of the switching contact 72A and the switching contact 72B of the relay 72 is switched to the connection line 55C, the first V-phase coil unit 55A and the second V connected in series via the connection line 55C. The end portion on the first V-phase coil portion 55A side of the phase coil portion 55B is connected to the V-phase power supply side connection point 55b via the connection line 55D-1, and the end portion on the second V-phase coil portion 55B side is connected to the connection line 55E-. 2 to the V-phase neutral point connection point 55a. Further, in W phase coil unit 456, when the connection destination of switching contact 72A and switching contact 72B of relay 72 is switched to connection line 56C, first W phase coil unit 56A and second W phase connected in series via connection line 56C. The end portion on the first W-phase coil portion 56A side of the coil portion 56B is connected to the W-phase power supply side connection point 56b via the connection line 56D-1, and the end portion on the second W-phase coil portion 56B side is connected to the connection line 56E-2. To the W-phase neutral point connection point 56a. Thereby, also in V phase coil part 455 and W phase coil part 456, each resistance 74 will be arranged outside the connection path of series connection.

  Therefore, by arranging each resistor 74 as shown in FIG. 27, it is possible to arrange the resistor 74 outside the connection path when the first coil portion and the second coil portion are connected in series in each phase. Therefore, it is possible to prevent a decrease in output even in the case of serial connection.

  Each resistor 74 is arranged on the right side surface of the circular substrate 71 (FIG. 3) as shown in FIG. As a result, the resistor 74 is disposed on the air path from the intake ports 31a, 31b to the exhaust port 31c of the cutting portion case 31, so that the heat generated by energization can be efficiently cooled.

  In the above-described embodiment, the case where the present invention is applied to a three-phase brushless DC motor and a tabletop circular saw equipped with the three-phase brushless DC motor has been described as an example. However, the present invention is not limited to this. Various modifications and improvements are possible within the scope described in the claims.

1 Desktop Circular Saw 52 Rotor 53, 153 Stator 54 U-phase Coil 54A First U-phase Coil 54A-1, 54A-2 First U-phase Coil 54B Second U-phase Coil 54B-1, 54B-2 Second U-phase Coil 55 V phase coil portion 55A First V phase coil portions 55A-1, 55A-2 First V phase coil 55B Second V phase coil portions 55B-1, 55B-2 Second V phase coil 56 W phase coil portion 56A First W phase coil portion 56A -1, 56A-2 1st W phase coil 56B 2nd W phase coil part 56B-1, 56B-2 2nd W phase coil 72 Relay 72A, 72B Switching contact 74 Resistance 531 Annular part 532, 1532 Teeth part 532A, 1532A Coil winding Part 532A-1, 1532A-1 Outer coil winding part 532A-2, 1532A-2 Inner coil winding part 532B Stop Part 1532D ribs C1 first conducting line C2 second conducting line

Claims (22)

A stator having an annular portion, and a plurality of tooth portions provided on an inner peripheral surface of the annular portion and projecting in a radial direction of the annular portion;
A coil wound around the teeth portion,
The coil includes a first coil wound around a radially outer portion of the teeth portion in one of the plurality of tooth portions, and a coil wound around a radially inner portion of the teeth portion than the first coil. And a second coil to be rotated. Each of the teeth portions includes a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction,
In each of the teeth portions, the first coil is wound around the radially outer portion of the plurality of coil winding portions, and the second coil is wound around the radially inner portion of the plurality of coil winding portions. The motor according to claim 1, wherein the motor is wound.   3. The motor according to claim 1, wherein in each of the tooth portions, the first coil and the second coil have the same number of turns.   4. The motor according to claim 1, wherein in each of the tooth portions, each coil has the same number of turns in the radial direction. 5.   5. The motor according to claim 1, wherein in each of the tooth portions, the coils have the same wire diameter.   6. The motor according to claim 1, wherein the plurality of coils wound around each of the tooth portions can be connected in parallel to each other. The plurality of tooth portions are composed of a plurality of tooth sets including a first tooth portion and a second tooth portion facing each other in the radial direction,
The first coil wound around the radially outer portion of the first tooth portion is wound around the radially inner portion of the second tooth portion via a jumper wire,
The second coil wound around the radially inner portion of the second teeth portion is wound around the radially outer portion of the first teeth portion via a jumper wire. Item 7. The motor according to any one of Items 1 to 6. A stator having an annular portion and a plurality of teeth portions provided on an inner peripheral surface of the annular portion and projecting in a radial direction of the annular portion;
Each tooth portion has a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction,
Each of the plurality of coil winding portions of each tooth portion includes a coil having the same number of turns.   The motor according to claim 8, wherein in each of the plurality of coil winding portions of each of the tooth portions, the coil has the same number of turns in the radial direction.   10. The motor according to claim 8, wherein the coil has the same wire diameter in each of the plurality of coil winding portions of each of the tooth portions.   The plurality of coils wound around the plurality of coil winding portions of each of the teeth portions can switch between parallel connection and series connection with each other. The motor described in. The plurality of tooth portions are composed of a plurality of tooth sets including a first tooth portion and a second tooth portion facing each other in the radial direction,
The first coil wound around the coil winding portion located on the radially outer side of the first tooth portion is the coil winding portion located on the radially inner side of the second tooth portion via a jumper wire. Wound around
The second coil wound around the coil winding portion located on the outer side in the radial direction of the second tooth portion is the coil winding located on the inner side in the radial direction of the first tooth portion via a jumper. The motor according to any one of claims 8 to 11, wherein the motor is wound around a portion. Each of the teeth portions includes a plurality of coil winding portions defined side by side in the radial direction,
The motor according to any one of claims 1 to 12, further comprising: a rib projecting between two adjacent coil winding portions of the plurality of coil winding portions. A stator having an annular part, and at least a pair of teeth provided on the inner peripheral surface of the annular part and projecting in the radial direction of the annular part;
A first coil including a pair of first winding portions wound around the pair of teeth portions;
A second coil including a pair of second winding portions wound around the pair of teeth portions;
The motor according to claim 1, wherein the first coil and the second coil have substantially the same resistance value.   The motor according to claim 14, wherein the pair of first winding portions and the pair of second winding portions have substantially the same length.   What are the winding positions of the first coil and the second coil in one of the pair of tooth portions, and the winding positions of the first coil and the second coil in the other of the pair of teeth portions? The motor according to claim 14, wherein the motor is reversed. Each of the pair of teeth portions includes a plurality of coil winding portions that are defined side by side in the radial direction and have substantially the same length in the radial direction,
The first coil has one of the pair of first winding portions wound around the coil winding portion located radially outward of one tooth portion and radially inward of the other tooth portion. The other one of the pair of first winding portions is wound around the coil winding portion located,
The second coil is wound around one of the pair of second winding portions around the coil winding portion located on the radially inner side in the one tooth portion, and in the other tooth portion, The motor according to any one of claims 14 to 16, wherein the other of the pair of second winding portions is wound around the coil winding portion located on the radially outer side. The first coil further includes a first crossover portion that connects one end and the other end of the pair of first winding portions,
The second coil further includes a second crossover portion connecting one end and the other end of the pair of second winding portions,
The motor according to claim 14, wherein the first crossover portion and the second crossover portion have different lengths.   The motor according to any one of claims 14 to 18, wherein the first coil and the second coil have substantially the same length. The first coil includes a first crossover portion that connects one end and the other end of the pair of first winding portions, and the other end and the other end of the pair of first winding portions. A pair of first connecting parts connectable to the other end, and
The second coil includes a second crossover portion connecting one end and the other end of the pair of second winding portions, and the other end and the other end of the pair of second winding portions. A pair of second connection parts connectable to the other end,
The first coil and the second coil can be connected in parallel to each other via the pair of first connection portions and the pair of second connection portions,
The motor according to claim 14, wherein one of the pair of first connection portions has a resistance connectable to the other end of the pair of first winding portions. A third connecting portion capable of connecting the other end of the pair of first winding portions and the other end of the pair of second winding portions;
The first coil is capable of switching a connection destination of one other end of the pair of first winding portions to either one of the pair of first connection portions or the third connection portion. Further comprising
The second coil is capable of switching a connection destination of one other end of the pair of second winding portions to one of the pair of second connection portions and the third connection portion. Further comprising
The first switching unit and the second switching unit are configured to connect a connection destination of one other end of the pair of first winding units and a connection destination of one other end of the pair of second winding units to the third. 21. The motor according to claim 20, wherein the first coil and the second coil are connected in series with each other by switching to a connection portion. The motor according to any one of claims 1 to 21,
And an output unit driven by the motor.

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