JP2010104212A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and light-weight brushless motor reducing a manufacturing cost. <P>SOLUTION: A bracket unit is composed of a bracket 15 fitted to a motor housing 11 with one end inserted in the axial direction of a rotating shaft 21 and a cover plate 55 assembled to cover the bracket 15 from one end in the axial direction. A control substrate 63 arranged with a predetermined distance with one end of the rotating shaft 21 in the axial direction is assembled to the cover plate 55. A sensor magnet 65 rotated together with the rotating shaft 21 is installed at one end of the rotating shaft 21 in the axial direction while a magnetic detector 66 arranged with a predetermined distance with the sensor magnet 65 and detecting the magnetic flux of the sensor magnet 65 is mounted on the control substrate 63. A controller 60 controlling the rotation of the rotating shaft 32 on the basis of the result of detection by the magnetic detector 66 is also mounted on the control substrate 63. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brushless motor.

2. Description of the Related Art Conventionally, an inner rotor type brushless motor is known as a servo motor that is mounted on a vehicle such as an automobile and used for an electric brake of the vehicle. The brushless motor includes a stator around which a coil is wound, a motor housing having an opening, in which the stator is fitted and fixed, and a rotor that is fitted and fixed to a rotating shaft and is rotatably supported with respect to the stator. And.
In order to drive this type of brushless motor, it is necessary to supply a current corresponding to the rotational position of the rotor to the coils of each phase. Therefore, in order to detect the rotational position and the rotational speed of the rotor, the brushless motor may be provided with rotational position detection means such as an encoder (magnetic detection unit) or a resolver.

  By the way, when providing a rotational position detection means in a brushless motor mounted on a vehicle, it is a mainstream to provide a resolver with a simple structure and excellent environmental resistance among the encoders and resolvers described above. The resolver includes a resolver rotor that is fixed to a rotating shaft, and a resolver stator that is disposed so as to surround the outer periphery of the resolver rotor. A resolver winding is wound around the resolver stator, and the resolver winding is electrically connected to a control device provided separately from the motor, and the gap permeance between the resolver rotor and the resolver stator is measured. Thus, the rotational position of the rotor can be detected.

  However, when a resolver is used as the rotational position detecting means, a harness for routing the resolver winding to an external control device is required, which leads to an increase in the weight and manufacturing cost of the brushless motor.

In order to cope with such a problem, a control circuit unit composed of a substrate on which a controller is mounted is assembled outside the motor housing in the radial direction, and the substrate of the control circuit unit and the resolver are electrically connected via a sensor terminal. A technique is known (see, for example, Patent Document 1).
JP 2004-129362 A

  However, in the resolver described above, the gap permeance between the resolver rotor and the resolver stator is detected as a voltage waveform, but in this case, a signal processing circuit for calculating the rotational position of the rotor from the detected voltage waveform becomes complicated. . Generally, in order to process a voltage waveform detected by a resolver, a dedicated IC is used. However, there is a problem that the use of this dedicated IC leads to an increase in manufacturing cost.

  In recent years, there is a need to prevent the brushless motor from being enlarged in the radial direction due to restrictions on the layout of a device (for example, a vehicle) on which the brushless motor is mounted. On the other hand, in patent document 1 mentioned above, since the control circuit part is assembled | attached to the radial direction outer side of the motor housing, there exists a problem that a brushless motor will enlarge in radial direction.

  Accordingly, the present invention has been made in view of the above-described circumstances, and provides a brushless motor capable of reducing the manufacturing cost while reducing the size and weight.

  In order to solve the above-described problems, an invention described in claim 1 includes a stator around which a coil is wound, a rotor fixed to a rotating shaft and supported rotatably with respect to the stator, and an opening. A brushless motor comprising: a motor housing in which the stator and the rotor are housed; and a bracket unit that closes the opening of the motor housing, wherein the bracket unit is fitted to the motor housing, A bracket body that is inserted at one end in the axial direction of the rotating shaft, and a cover plate that is assembled so as to cover the bracket body from one end in the axial direction. The cover plate includes one end in the axial direction of the rotating shaft. And a control board arranged opposite to each other with a predetermined interval between them, and at one end in the axial direction of the rotating shaft, A sensor magnet that rotates together with the rotating shaft is provided, and a magnetic detection unit that detects a magnetic flux of the sensor magnet is mounted on the control board so as to face the sensor magnet with a predetermined distance. And a controller for controlling the rotation of the rotating shaft based on the detection result of the magnetic detection unit.

  According to a second aspect of the present invention, the controller includes a sensor signal processing function that calculates a rotational position of the rotor based on a detection result by the magnetic detection unit, and a calculation result by the sensor signal processing function. And a motor control function for controlling the current supplied to the coil by opening and closing the switching element.

According to the first aspect of the present invention, the control board is assembled to the cover plate of the bracket unit, and the controller and the magnetic detection unit are mounted on the control board, whereby the controller and the magnetic detection unit are connected to the wiring pattern of the control board. Can be connected. Thus, unlike a conventional case where a control device for calculating the rotational position of the rotor is provided outside, a harness or the like is not used to connect the magnetic detection unit and the controller. Therefore, the number of parts can be reduced and the structure can be simplified, so that the manufacturing cost can be reduced and the weight of the apparatus can be reduced. In addition, since the signal from the magnetic detection unit is directly input to the controller via the wiring pattern, it is difficult to be affected by external noise, and signals can be transmitted and received at a low voltage between the magnetic detection unit and the controller. .
Moreover, since the control board on which the magnetic detection unit and the controller are mounted is assembled to the cover plate, the control board can be positioned with respect to the bracket body simply by assembling the cover plate to the bracket body. That is, the relative position between the sensor magnet and the magnetic detection unit is determined by assembling the bracket unit to the motor housing. Therefore, gap management in the axial direction between the sensor magnet and the magnetic detection unit is facilitated, and highly accurate sensing can be performed.
Further, by arranging the control board described above on one end side of the rotating shaft, the motor can be downsized in the radial direction as compared with the conventional case where the control circuit unit is provided outside the motor in the radial direction. It becomes possible. Therefore, the assembly | attachment property of an apparatus can be improved.

  According to the second aspect of the present invention, the controller is provided with a sensor signal processing function and a motor control function, so that the controller controls the current supplied to the coil by switching the switching element, and the rotational position of the rotor. Can also be calculated. As a result, it is not necessary to provide a dedicated IC as a separate body in order to calculate the rotational position of the rotor, so that the manufacturing cost can be further reduced.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the brushless motor 10 is an electromechanically integrated brushless motor 10 used as an electric brake motor of an automobile, and includes a stator 12 fitted and fixed to a bottomed cylindrical motor housing 11; The rotor 13 is provided so as to be rotatable with respect to the stator 12, and a bracket (bracket body) 15 for closing the rotor is provided in the opening 14 of the motor housing 11. In the following description, the axial direction of the brushless motor 10 in FIG. 1 is defined as the left-right direction, the right side along the axial direction is defined as one axial end side, and the left side along the axial direction is defined as the other axial end side.

  The motor housing 11 has an opening 14 that opens toward one end in the axial direction, and an end (bottom) 16 is formed on the other end in the axial direction. A boss portion 17 that protrudes from the inner surface of the end portion 16 toward the one end side in the axial direction is formed at the center portion in the radial direction of the end portion 16. An insertion hole 18 for inserting the rotary shaft 21 of the rotor 13 is formed in the central portion of the boss portion 17 in the radial direction, and a bearing housing 19 into which the bearing 20a is press-fitted is formed inside the boss portion 17. . And the other end side of the rotating shaft 21 of the rotor 13 is rotatably supported because the rotating shaft 21 is fitted and fixed to this bearing 20a. Further, an O-ring groove 22 for attaching an O-ring (not shown) is formed on the outer peripheral surface of the end portion 16, and a reduction gear or the like is attached so as to be fitted to the end portion 16. .

Inside the peripheral wall 23 of the motor housing 11, a stator accommodating portion 23 a formed on the other axial end side and a bracket accommodating portion 23 b formed on one axial end side and having a diameter larger than the stator accommodating portion 23 a are configured. ing.
The stator 12 is fitted and fixed in the stator housing portion 23 a of the motor housing 11. The stator 12 has a substantially cylindrical stator core 30. The stator core 30 is formed by laminating a plurality of metal plates (electromagnetic steel plates) punched into a substantially annular shape by press working in the axial direction of the rotary shaft 21, and a plurality of teeth portions 32 for winding the coils 31 are radially provided. Is formed. An insulator 33 that is an insulating material is attached to each tooth portion 32 over the entire circumference, and coils 31 corresponding to the three phases of the U phase, the V phase, and the W phase are wound on the insulator 33. .

  An annular bus bar unit 35 having an opening 35 a is disposed on one end side of the stator 12 in the axial direction so as to surround the periphery of the rotating shaft 21. The bus bar unit 35 is formed by embedding a plurality of bus bars 37 in a resin mold body 36, and is arranged in a state in which an end surface on the other end side in the axial direction is in contact with an end surface on one end side in the axial direction of the insulator 33. Yes. The bus bar unit 35 has a role of electrically connecting the stator winding 31a drawn from the coil 31 of the stator 12 and an external device (not shown). At one end of the bus bar 37, a phase terminal 37 a that protrudes radially outward from the outer peripheral surface of the resin mold body 36 is formed, and the stator windings drawn from the phase terminal 37 a and the coil 31 of each phase are formed. The line 31a is connected to each other. On the other hand, at the other end of the bus bar 37, a power feeding unit 37b connected to a power terminal 61 drawn from a control board 63 described later is configured.

  Further, a bracket insulator 40 is provided outside the bus bar unit 35 in the radial direction so as to surround one end side in the axial direction of the bus bar unit 35 and the stator 12. The bracket insulator 40 is intended to insulate between the bracket 15 and the bus bar unit 35 and to prevent dust from entering the motor housing 11, and is formed larger than the diameter of the stator housing portion 23a. And has a cylindrical portion 40 a disposed along the inner peripheral surface of the peripheral wall 15 a of the bracket 15. The other end side in the axial direction of the cylindrical portion 40a is inserted to a position where it abuts against a shoulder portion 23c formed between the bracket housing portion 23b and the stator housing portion 23a of the motor housing 11.

An inner flange portion 40b is formed on one end side in the axial direction of the tubular portion 40a so as to project toward the radially inner side. The inner flange portion 40b extends radially inward so as to cover one end side of the bus bar unit 35 in the axial direction.
On the other hand, an outer flange portion 40c is formed on the other end side in the axial direction of the tubular portion 40a so as to project outwardly in the radial direction from the inner peripheral surface of the bracket housing portion 23b of the motor housing 11. Thereby, the bracket insulator 40 is in a state in which the other axial end is in contact with the shoulder portion 23c of the motor housing 11, and the outer peripheral surface of the outer flange portion 40c protrudes from the inner peripheral surface of the bracket housing portion 23b. It is held in the bracket housing part 23 b of the housing 11. Thereby, the movement of the bracket insulator 40 in the axial direction can be restricted.

  The rotor 13 has a rotor core 42 that is externally fitted and fixed to the other end of the rotating shaft 21 so as to face the inner peripheral surface of the stator 12. The rotor core 42 is formed by laminating metal plates (electromagnetic steel plates) in the axial direction, and press-fitting holes 43 for press-fitting the rotary shaft 21 are formed at substantially the center in the radial direction of the rotor core 42. On the outer peripheral side of the rotor core 42, a plurality of permanent magnets 44 are arranged so that the magnetic poles are changed in order in the circumferential direction.

  The bracket 15 is formed in a substantially disk shape in plan view, and a cylindrical housing inlay portion 50 that is fitted to the bracket housing portion 23b of the motor housing 11 is provided on the other axial end side. Yes. An O-ring groove 25 is formed on the outer peripheral surface of the housing inlay part 50 over the entire circumference in the circumferential direction. With the O-ring 26 disposed in the O-ring groove 25, the housing inlay part 50 is placed in the bracket housing part 23 b. Is fitted.

  A boss 51 that protrudes toward the other end in the axial direction is formed at the radial center of the bottom 15 b of the bracket 15. The boss 51 is disposed so as to face the opening 35 a of the bus bar unit 35. Yes. An insertion hole 52 for inserting the rotating shaft 21 of the rotor 13 is formed in the central portion in the radial direction of the boss portion 51, and a bearing housing 53 into which the bearing 20 b is press-fitted is formed inside the boss portion 51. . Then, the rotary shaft 21 is fitted and fixed to the bearing 20b, so that one end side of the rotary shaft 21 of the rotor 13 is rotatably supported.

  On the other hand, a recess 24 surrounded by the peripheral wall 15a is formed on one end side in the axial direction of the bracket 15, and a cover plate 55 is assembled so as to close the recess 24. The cover plate 55 is formed in a substantially disc shape, and is fitted and fixed to the opening edge of the recess 24 of the bracket 15 with an O-ring 56 interposed therebetween. A heat sink 57 is integrally formed on the outer surface side of the cover plate 55. The bracket 15 and the cover plate 55 constitute a bracket unit that closes the opening 14 of the motor housing 11.

  Here, a controller unit 59 that controls driving of the brushless motor 10 is provided in a space between the recess 24 of the bracket 15 and the cover plate 55, that is, in one axial end side of the rotating shaft 21. The controller unit 59 includes a sensor unit 62 for detecting the rotational position of the rotor 13, a control board 63 screwed to the cover plate 55, a controller 60 mounted on the control board 63, and the inner surface side of the cover plate 55. And a switching element 64 arranged at the same position.

The sensor unit 62 is mounted on the sensor magnet 65 provided at one end of the rotating shaft 21 and the main surface (surface on the other end side in the axial direction) of the control board 63, and a predetermined distance is provided between the sensor unit 62 and the sensor magnet 65. And a magnetic detection unit 66 arranged to face each other.
The sensor magnet 65 is provided on one end surface of the rotary shaft 21 disposed so as to face the concave portion 24, and a plurality of magnetic poles are magnetized in the circumferential direction on the outer peripheral surface thereof.
On the other hand, the magnetic detection unit 66 detects a change in the magnetic flux of the sensor magnet 65 accompanying the rotation of the rotary shaft 21, and outputs the detection result to the controller 60. For example, a Hall element or an MR (Magneto-Resistance) element Etc. are used. The magnetic detection unit 66 is mounted at the central portion in the radial direction of the control board 63 and faces the end surface of the sensor magnet 65 on one end side in the axial direction with a predetermined distance therebetween.

The control board 63 is disposed such that the normal direction of the main surface coincides with the axial direction of the rotary shaft 21 with a predetermined interval between the control board 63 and one axial end face of the rotary shaft 21. On the 63, wiring patterns (both not shown) for the sensor unit and the motor drive are formed.
One end of the wiring pattern for the sensor unit is connected to the magnetic detector 66, and the other end is connected to a terminal 67 provided on the control board 63 via the controller 60. On the other hand, the wiring pattern for driving the motor has one end connected to the power feeding portion 37b drawn from the bus bar unit 35 via the power terminal 61 and the other end connected to the control board 63 via the controller 60. 67. In FIG. 1, only one terminal 67 is shown for the sake of illustration, but actually, a plurality of terminals for sensor unit and motor driving are arranged side by side, and for these sensor units and motor driving are arranged in these terminals. Each wiring pattern is connected. On the control board 63, a circuit such as a power supply voltage monitor is also mounted.

  A through hole 68 for connecting the power terminal 61 and the power feeding portion 37b is formed in the lower portion (lower portion in FIG. 1) of the peripheral wall 15a of the bracket 15. The through hole 68 is sealed by a cap 70 with an O-ring 69 interposed between the power terminal 61 and the power feeding portion 37b.

  A connector 71 for connecting the brushless motor 10 and an external device (not shown) is formed on the upper portion (upper portion in FIG. 1) of the peripheral wall 15a of the bracket 15. The connector 71 is provided with a plurality of power supply terminals 72. The power supply terminals 72 are routed into the bracket 15 and connected to the terminals 67 drawn from the control board 63. Then, a coupler (not shown) of an external device is connected to the connector 71, and each sensor unit and motor driving terminal 67 is connected to the external device (not shown) via a power supply terminal 72. A through hole 73 for connecting the power supply terminal 72 and each terminal 67 is formed in the bottom portion 15 b of the bracket 15.

Here, the controller 60 is mounted on the main surface of the control board 63. The controller 60 has a sensor signal processing function (not shown) and a motor control function (not shown).
The sensor signal processing function calculates the rotational position of the rotor 13 based on the detection result by the magnetic detection unit 66, and is connected between the magnetic detection unit 66 and an external device via the wiring pattern of the control board 63. ing. The sensor signal processing function calculates the rotational position of the rotor 13 and then outputs a signal of the calculation result to an external device. The external device calculates a current value to be supplied to the coil 31 based on the rotational position of the rotor 13, and outputs a signal of the calculation result to the motor control function.
The motor control function receives the calculation result of the current value calculated by the external device, and outputs a PWM (Pulse Width Modulation) signal for controlling ON / OFF of the switching element 64 based on the calculation result, and the coil 31 of each phase. Every one is created.
As described above, the control board 63 of the present embodiment is opposed to the sensor magnet 65 with a predetermined distance therebetween, and the magnetic detection unit 66 that detects the magnetic flux of the sensor magnet 65, and the magnetic detection unit 66. And a controller for controlling the rotation of the rotating shaft 21 based on the detection result of the above.

A switching element 64 is provided on the inner surface of the cover plate 55, that is, on the opposite surface of the heat sink 57. The switching element 64 switches energization to each coil 31 and is connected to a motor driving wiring pattern via a connection terminal 74 between the motor control function and the bus bar unit 35. . Here, in the controller unit 59, by disposing the switching element 64, which is a heat generation source, on the opposite side of the heat sink 57, the switching element 64 can be efficiently dissipated.
The switching element 64 has a configuration in which a transistor such as a field effect transistor (FET) and a diode that prevents reverse flow between the drain and source of the FET are connected in parallel to an external device (not shown). is doing. The switching element 64 forms an H bridge circuit for each phase, and the current supplied to each coil 31 by switching each switching element 64 on and off based on the PWM signal output from the motor control function. Switches for each phase.

Next, the operation will be described.
As shown in FIG. 1, when the rotating shaft 21 rotates, the magnetic flux generated from the sensor magnet 65 changes, and this magnetic flux change is detected by the magnetic detection unit 66. The magnetic detection unit 66 outputs information indicating a change in magnetic flux as an electric signal toward the sensor signal processing function of the controller 60. The sensor signal processing function calculates the rotational position of the rotor 13 based on this electrical signal, and outputs a signal of this calculation result to an external device. Then, the external device calculates a current value for supplying power to the coil 31 from the rotational position of the rotor 13, and outputs a signal of this calculation result to the motor control function of the controller 60.

The motor control function receives a calculation signal of a current value calculated by an external device, and creates a PWM signal for each phase coil 31 based on this calculation signal. Then, the motor control function outputs the created PWM signal toward the switching element 64. The switching element 64 that has received the PWM signal is switched between ON and OFF based on the PWM signal, so that the current supplied to each coil 31 is switched for each phase.
Thereby, since a desired current can be passed through the predetermined coil 31 of the brushless motor 10, the rotation control of the brushless motor 10 can be performed.

Therefore, according to the present embodiment, the control board 63 is assembled to the cover plate 55 of the bracket unit, and the controller 60 and the magnetic detection part 66 are mounted on the control board 63, whereby the magnetic detection part 66 and the sensor of the controller 60 are mounted. The signal processing function can be connected by the wiring pattern of the control board 63. Thus, unlike a conventional case where a control device for calculating the rotational position of the rotor 13 is provided outside, a harness or the like is not used to connect the magnetic detection unit 66 and the controller 60. Therefore, the number of parts can be reduced and the structure can be simplified, so that the manufacturing cost can be reduced and the weight of the apparatus can be reduced. Further, since the signal from the magnetic detection unit 66 is directly input to the controller 60 via the wiring pattern, it is difficult to be affected by external noise, and the signal is transmitted and received at a low voltage between the magnetic detection unit 66 and the controller 60. Is possible.
Moreover, since the control board 63 on which the magnetic detection unit 66 and the controller 60 are mounted is assembled to the cover plate 55 by screwing, the control board 63 is positioned relative to the bracket 15 only by assembling the cover plate 55 to the bracket 15. It can be performed. That is, the relative position between the sensor magnet 65 and the magnetic detection unit 66 is determined by assembling the bracket unit to the motor housing 11. Therefore, gap management in the axial direction between the sensor magnet 65 and the magnetic detection unit 66 is facilitated, and highly accurate sensing can be performed.

  In the present embodiment, the controller 60 is configured with a sensor signal processing function and a motor control function, so that the controller 60 calculates the rotational position of the rotor 13 and switches the switching element 64 between ON and OFF. It is also possible to create a PWM signal and control the current supplied to the coil 31. As a result, it is not necessary to provide a dedicated IC as a separate body in order to calculate the rotational position of the rotor 13, so that the manufacturing cost can be further reduced. In the present embodiment, by using the sensor unit 62 instead of the resolver, the signal processing of the magnetic detection unit 66 is less burdened on the controller 60 than the signal processing of the resolver. Therefore, both the sensor signal processing function and the motor control function can be mounted on the controller 60.

  Here, in the present embodiment, the controller unit 59 is arranged on one end side in the axial direction of the rotating shaft 21, so that the brushless circuit is provided as compared with the conventional case where the control circuit unit is provided on the outer side in the radial direction of the motor. An increase in the size of the motor 10 in the radial direction can be prevented. Therefore, it is possible to improve the assembling property when the vehicle is mounted.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific shape, configuration, and the like given in the present embodiment are merely examples, and can be changed as appropriate.
For example, in the above-described embodiment, the case where the brushless motor is used for a vehicle brake device has been described. However, the present invention is not limited to this.
In the above-described embodiment, the inner rotor type brushless motor has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to an outer rotor type brushless motor.

It is sectional drawing of the brushless motor in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Brushless motor 12 ... Stator 13 ... Rotor 31 ... Coil 60 ... Controller 63 ... Control board 65 ... Sensor magnet 66 ... Magnetic detection part

Claims (2)

A stator wound with a coil;
A rotor fixed to a rotating shaft and supported rotatably with respect to the stator;
A motor housing having an opening and containing the stator and the rotor;
In a brushless motor comprising a bracket unit that closes the opening of the motor housing,
The bracket unit is fitted to the motor housing, and a bracket body in which one axial end side of the rotating shaft is inserted;
It is composed of a cover plate assembled so as to cover the bracket body from one end side in the axial direction,
The cover plate is assembled with a control board that is arranged oppositely with a predetermined interval between one end in the axial direction of the rotating shaft,
While one end of the rotating shaft in the axial direction is provided with a sensor magnet that rotates with the rotating shaft,
The control board is mounted opposite to the sensor magnet with a predetermined distance therebetween, and a magnetic detection unit for detecting the magnetic flux of the sensor magnet is mounted on the basis of the detection result by the magnetic detection unit. And a controller for controlling the rotation of the rotating shaft. The controller includes a sensor signal processing function for calculating a rotational position of the rotor based on a detection result by the magnetic detection unit;
The brushless motor according to claim 1, further comprising: a motor control function for controlling a current supplied to the coil by opening and closing a switching element based on a calculation result by the sensor signal processing function.

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