WO2022137980A1 - Work machine - Google Patents

Abstract

A work machine that employs insert molding for fixing a bearing to a housing is provided. The work machine comprises a resin-made tubular integrated motor housing 2 that accommodates a motor 5, and a bearing 14a that pivotally supports a rotating shaft 9 of the motor 5, wherein the bearing 14a is fixed to the motor housing 2 by insert molding. A labyrinth mechanism 40 is provided in the motor housing 2 so that cooling air is taken in from the outside and that the cooling air does not directly act on the bearing 14a. The labyrinth mechanism 40 is composed of a labyrinth fixing portion 25 formed on the motor housing 2 side and a labyrinth rotating member 41 attached to the rotating shaft 9, and a labyrinth structure is formed by arranging cylindrical portions 25a and 44 close to each other so that the cylindrical portions overlap each other thereby improving dust resistance and durability of the bearing 14a.

Description

Working machine

The present invention relates to a working machine driven by a motor, and more particularly to strengthening dustproofing of a bearing holding the motor.

A working machine that performs operations such as cutting and polishing by rotating a tip tool using an electric motor is known. In Patent Document 1, a working machine such as a grinder using a brushless DC motor as a drive source is known. In a brushless DC motor, a rotor having a permanent magnet is fixed to the rotating shaft, a coil is wound around a stator core on the outer peripheral side to form a stator, and a control device detects the rotational position of the rotor using a magnetic sensor. The motor is rotated by supplying an exciting current to the windings of the motor. As an example of a working machine using such a brushless motor, a working machine as in Patent Document 1 is known. FIG. 10 is a diagram showing a conventional grinder 101 shown in Patent Document 1.

In FIG. 10, in the conventional grinder 101, the brushless motor 5 is housed coaxially with the cylindrical motor housing 102. The stator 8 having the coil of the brushless motor 5 is fixed to the motor housing 102, and the rotating shaft 9 holding the rotor 6 on the inner peripheral side is pivotally supported by bearings 114a and 114b on the front side and the rear side of the motor 5. A disk-shaped sensor magnet 63 is provided at the rear end of the rotating shaft 9, and a rotating position detecting element 62 such as a Hall IC for detecting the position of the sensor magnet 63 is provided in the vicinity thereof.

Japanese Unexamined Patent Publication No. 2019-198951

In the conventional grinder 101 shown in FIG. 10, in order to assemble the motor 5 in the motor housing 102 forming a tubular integrated structure, the stator 8 is first arranged and then the rotor 6 is inserted. In the case of such an assembly procedure, a stator core having a permanent magnet on the rotating shaft 9 of the motor 5 is first attached to the cylindrical integrated motor housing 102. Next, the balancers 11a and 11b are attached to the front and rear of the rotor 6, and the dust seal 125 and the bearing 114a are further attached to the rear end of the rotor 6, and the assembly of these rotors 6 is inserted into the stator 8. It is mounted in place within the motor housing 102. At this time, the bearing 114a fixed to the rear end portion of the rotating shaft 9 cannot be configured to be larger than the inner diameter of the core of the stator 8 because it penetrates the inside of the core of the stator 8. As a result, it is necessary to adopt a small bearing 114a, and it is difficult to improve durability and the like. Further, since the motor housing 102 is integrally molded with synthetic resin, it can be placed at a predetermined mounting position of the motor housing 102 of the bearing 114a. The bearing 114a is attached so as to be press-fitted, but in the case of fixing by press-fitting, the fixing force of the bearing 114a may not be stable depending on the air temperature and the amount of water at the time of press-fitting. Further, in such a grinder 101, dust may be mixed with the cooling air taken into the inside from the outside of the motor housing 102 by the cooling air of the motor 5, so that the shaft support performance of the bearing 114a that pivotally supports the motor 5 and the shaft support performance There was a risk of adversely affecting the service life.

The present invention has been made in view of the above background, and an object thereof is to provide a working machine capable of firmly holding a bearing against a housing made of synthetic resin and improving the rotational accuracy of a motor shaft. There is something in it. Another object of the present invention is to provide a working machine in which a labyrinth structure is provided in a bearing portion of a motor to improve dust resistance. Still another object of the present invention is to provide a working machine capable of ensuring durability by making the outer diameter of the bearing larger than the inner diameter of the stator core.

The following is a description of typical features of the invention disclosed in the present application. According to one feature of the present invention, it has a motor, a housing for accommodating the motor, a bearing member that pivotally supports the motor, and a tip tool driven by the motor, and the bearing member is driven by the housing in the motor axial direction. Movement is restricted. According to another feature of the present invention, it has a motor, a housing that houses the motor, a bearing member that pivotally supports the motor, and a tip tool driven by the motor, and the bearing member is insert-molded into the housing. Will be done. The housing includes a resin tubular integrated motor housing, and the bearing members are insert-molded so as to be coaxial with the central axis of the motor housing. In addition, the housing is provided with an intake port and an exhaust port, a fan is provided on the rotating shaft of the motor, and the housing is radially inside the outer peripheral edge of the bearing member so as to come into contact with a part of the side surface of the bearing member. A wall portion is provided on the housing, and this wall portion forms a labyrinth structure. Further, the motor has a stator and a rotor, the rotor is provided with a labyrinth member, a cylindrical portion extending in the rotation axis direction is formed on the wall portion, and the labyrinth structure is formed by the labyrinth member and the wall portion. Will be done.

According to another feature of the present invention, the working machine has a motor, a housing for accommodating the motor, and a bearing member that pivotally supports the motor, the motor has a stator, and the outer diameter of the bearing member is the stator. It was configured to be larger than the inner diameter. This bearing member is held by being insert-molded into the housing, or is held so as to be inserted into the bearing holding portion formed in the housing from the anti-stator side.

According to still another feature of the present invention, the working machine has a motor, a housing for accommodating the motor, and a bearing member that pivotally supports the motor, and is integrally formed with the housing on one end side of the bearing member. A labyrinth structure is formed by a wall member attached to a wall member or a separate body and a tubular member attached to a part of the motor. The motor has a stator, a rotor, and a rotating shaft that fixes the rotor, and the tubular member is fixed to the rotor, the rotating shaft, or both. A bearing holding portion for holding the outer ring of the bearing member is formed in the housing, and the outer diameter of the bearing member is preferably equal to or larger than the inner diameter of the stator. Further, the outer diameter of the tubular member may be smaller than the outer diameter of the rotor and the outer diameter of the bearing member. The housing is cylindrical, one side of the space accommodating the motor is opened, the other side is provided with a wall portion forming a bearing holder for holding the bearing member, and the stator is inserted into the housing through the opening. ..

According to the present invention, since insert molding is adopted for fixing the bearing to the housing, the bearing can be firmly held against the housing, and the rotation accuracy of the motor can be improved. Further, since the insert molding eliminates the need for bearing fixing members (screws and the like), the manufacturing cost can be reduced. Furthermore, when assembling the rotor assembly into the housing after mounting the stator core, the bearing is already inserted in the housing, eliminating the need for the bearing to penetrate the inside of the rotor core, thus limiting the bearing size. It disappears. In addition, the bearing can be made larger than before, and the adoption of a large bearing can ensure sufficient durability.

It is a vertical sectional view which shows the whole structure of the grinder 1 which concerns on embodiment of this invention. It is a front view of the motor housing 2 alone of FIG. It is a partially enlarged view around the labyrinth mechanism 40 of the grinder 1 of FIG. It is a partially enlarged view around the labyrinth mechanism 80 of the grinder 1A which concerns on the 2nd Embodiment of this invention. It is a partially enlarged view of the vicinity of the labyrinth mechanism 90 of the grinder 1B according to the third embodiment of the present invention. It is a partially enlarged view around the labyrinth mechanism 90A of the grinder 1C which concerns on the modification of the 3rd Example of this invention. It is a partial vertical sectional view which shows the structure of the conventional grinder 101.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following figures, parts having the same function are designated by the same reference numerals, and the description of repetition will be omitted. Further, in the present specification, the front-back, left-right, and up-down directions are described as the directions shown in the drawings.

FIG. 1 is a top view of a grinder 1 according to an embodiment of the present invention. Here, as an example of a working machine, a grinder 1 is provided in which a spindle 31 that rotates in a direction orthogonal to the rotation axis 9 of the motor 5 is provided, and the tip tool connected to the spindle 31 is a circular grindstone 65. The housing (outer frame or housing) of the grinder 1 includes a gear case 30 for accommodating a power transmission mechanism, a cylindrical integrally molded motor housing 2 for accommodating a motor 5, and electrical equipment attached to the rear of the motor housing 2. It is composed of three main parts of the cylindrical rear cover 3 that houses the class. The method of forming the housing is arbitrary, and it may be configured by three parts in the front-rear direction as in this embodiment, the motor housing 2 and the rear cover 3 may be integrally configured, or other divisions. It may be formed in a shape. The motor housing 2 is made of resin and is manufactured by a substantially cylindrical integral molding having an opening 2a on the front side and an opening 2b on the rear side. The inner diameter of the portion of the motor housing 2 in which the motor 5 is housed has a diameter slightly larger than the outer diameter of the stator core 8a of the motor 5, and constitutes a portion (grip portion) to be gripped by an operator with one hand. The opening 3a of the rear cover 3 is connected to the opening 2b on the rear side of the motor housing 2. The rear cover 3 is integrally molded into a cylinder, but it can also be formed into two left and right parts.

The motor 5 is a three-phase brushless DC motor in which a rotating shaft 9 is arranged along the central axis direction (front-back direction) of the motor housing 2. In the motor 5, the rotor rotates in the space on the inner peripheral side of the stator core 8a having a substantially cylindrical shape. The stator core 8a is manufactured by a laminated structure of an annular thin iron plate. Six teeth (not shown) are formed on the inner peripheral side of the stator core 8a, and resin insulators 8b and 8c are mounted in the axial front-rear direction of each tooth, and the teeth are sandwiched between the insulators 8b and 8c. A copper wire is wound in a rectangular shape to form a coil 8d. In this embodiment, the coil 8d is a star connection or a delta connection having three phases of U, V, and W phases, and three lead wires for U, V, and W phases for supplying drive power to the coil 8d (3 lead wires for U, V, and W phases. (Not shown) is connected to the circuit board 50. On the inner peripheral side of the stator core 8a, the rotor 6 is fixed to the rotating shaft 9. The rotor 6 is a stack of a large number of thin annular thin iron plates in the axial direction, and has a flat plate-shaped permanent magnet 7 having N and S poles in a slot portion having a rectangular cross section (see FIG. 3 below for reference numerals). Will be inserted.

The rotating shaft 9 has a rear bearing (first bearing member) 14a fixed to the motor housing 2 and a front bearing (second bearing) fixed near the connection portion between the gear case 30 and the motor housing 2. It is rotatably held by the member) 14b. A cooling fan 15 is provided between the bearing 14b and the motor 5 when viewed in the axial direction of the rotating shaft 9. The cooling fan 15 is, for example, a plastic centrifugal fan, and when the motor 5 rotates, it rotates in synchronization with the rotating shaft 9, so that the motor 5, the control circuit, and the like are formed in the directions indicated by a plurality of black arrows inside the housing. Generates a flow of wind (cooling air) to cool the air.

The cooling air is sucked from suction ports (not shown) provided on the left and right side wall surfaces of the rear cover 3 near the rear end of the circuit board 50, and is rearward so as to pass around the controller case 55 accommodating the circuit board 50 and the sensor board 61. It flows from the rear to the front side, passes through the openings 27a to 27d (see FIG. 2) formed in the bearing holding portion 20 of the motor housing 2 from the rear to the front side, and flows into the accommodation space of the motor 5. In the bearing holding portion 20, a plurality of columns (described later in 24a to 24f in FIG. 2) are formed outward from the cylindrical portion (bearing holder 23) that holds the outer ring portion of the bearing 14a (see FIG. 1), and other than the columns. Since it is hollow in the place of, the cooling air flows from the space side where the controller case 55 is housed to the space side where the motor 5 is housed.

The cooling air that has flowed into the accommodation space of the motor 5 is located on the outer peripheral side of the stator core 8a and between the motor housing 2 (see the black arrow in the figure) and inside the stator core 8a and between the rotor 6 and the rotor 6. It is sucked by the cooling fan 15 through the through hole in the center of the fan guide 17 through the space, and is sucked by the cooling fan 15 through the through hole of the fan cover 16 to the front side from the through hole (exhaust port) 30b of the gear case 30 or the fan cover 16. It is discharged forward from the lower hole (exhaust port) 16b. In this embodiment, the circuit board 50, the sensor magnet 63, the bearing 14a, the motor 5, the cooling fan 15, and the bearing 14b are viewed from the rear (wind side) to the front side when viewed on the axis of the rotating shaft 9 of the motor 5. Are arranged in series (on a straight line) in the axial direction. The intake air windows for sucking the outside air are arranged on the left and right side surfaces of the circuit board 50 (not visible in FIG. 1). In this embodiment, the elements (switching elements, diode bridges, etc.) that generate heat due to the cooling air flowing from the rear side to the front side of the housing when viewed in the direction of the rotation axis of the motor 5 and the motor are effectively cooled. The bearings 14a and 14b are not exposed in the air passage of the cooling air flow.

The gear case 30 is made by integrally molding a metal such as aluminum, and accommodates a power transmission mechanism composed of a set of bevel gears (19, 33) and rotatably holds a spindle 31 as an output shaft. .. The spindle 31 is arranged so as to extend in the axis B1 direction (here, the vertical direction) substantially orthogonal to the axis A1 direction (here, the front-rear direction) of the rotation axis of the motor 5. A first bevel gear 19 is provided at the front end portion of the rotary shaft 9, and the first bevel gear 19 meshes with a second bevel gear 33 attached to the upper end portion of the spindle 31, and the power transmission means is used. Acts as a deceleration mechanism. The upper end side of the spindle 31 is rotatably supported by the gear case 30 by a cylindrical metal 32a, and is pivotally supported by a bearing 32b by a ball bearing near the center. The bearing 32b is fixed to the gear case 30 by two screws 35 via the spindle cover 34.

A wheel washer 37a is provided at the tip of the spindle 31, and a tip tool such as a grindstone 65 is attached by the wheel nut 37b. The grindstone 65 is, for example, a resinoid flexible toy, a flexible toy, a resinoid toy, a sanding disc, a bevel wire brush, a non-woven fabric brush, a diamond wheel, or the like having a diameter of 100 mm. Surface polishing and curved surface polishing are possible. The radial outer side and the upper side of the rear side of the grindstone 65 are covered with the wheel guard 39.

A sensor magnet 63, which is a magnetic material having different magnetic poles in the rotation direction, is attached to the rear end of the rotation shaft 9 of the motor 5. The sensor magnet 63 is a thin cylindrical permanent magnet attached for detecting the rotational position of the rotor 6, and N poles and S poles are sequentially formed by 90 degrees in the circumferential direction. A substantially semicircular sensor substrate 61 arranged in the direction perpendicular to the rotation axis 9 is provided on the rear side of the sensor magnet 63 and inside the controller case 55, and the position of the sensor magnet 63 is located on the sensor substrate 61. A rotation position detection element 62 for detection is provided. The rotation position detecting element 62 detects the rotation position of the rotor 6 by detecting the change in the magnetic field of the rotating sensor magnet 63. For example, the Hall IC is composed of a Hall IC, and the Hall IC is in the rotation direction of the rotor 6. Three are provided for each predetermined angle, here every 60 °.

Inside the rear cover 3 formed in a substantially cylindrical shape, there are a control circuit (not shown) that controls the rotation of the motor 5, an inverter circuit (not shown) that drives the motor 5, and a power supply cord 58. A power supply circuit (not shown) for converting alternating current supplied to direct current is accommodated. These circuits are mounted on a common circuit board 50. The circuit board 50 is arranged inside a container-shaped controller case 55 having an opening surface so as to be parallel to the central axis in the longitudinal direction of the grinder 1 (coaxial with the rotation axis 9 of the motor 5). The inside of the controller case 55 is entirely covered with a curable resin that cures from a liquid state. The opening surface of the controller case 55 is arranged so as to face downward, and a plurality of switching elements (for example, FETs) included in the inverter circuit are arranged so as to face downward from the circuit board 50.

The grinder 1 according to the embodiment of the present invention is a tool mainly for processing by rotating a grindstone 65 attached to a spindle 31 to polish and grind a processed material, and chips and dust are generated during processing. do. For this reason, since the grinder 1 is a work machine that is often used in an environment where dust is soaring, even if chips, dust, etc. flow in from the intake air windows formed on both the left and right sides of the rear cover 3, the effect is affected. It is designed to be inferior. For example, a filter or the like is attached to prevent dust from being taken in from the wind window. Nevertheless, the use of the grinder 1 for many years may cause dust to reach the bearing, particularly the bearing 14a. This is because the bearing 14a cannot be completely sealed in the air passage because the rotating shaft 9 is fixed to the bearing 14a. Therefore, in the conventional grinder 101, a dust seal 125 is provided in the vicinity of the bearing 14a (see FIG. 10). On the other hand, in order to prevent the influence of dust on the control circuit, the controller case 55 is arranged so that the opening faces downward to prevent dust from accumulating inside the controller case 55. When the worker completes the work, the grinding machine 1 is placed on the ground or the like, but unless there are special circumstances, the grinding machine 1 is placed in the same orientation as it is held. That is, the grinder 1 is placed with the spindle 31 facing downward. Therefore, for example, even if dust or the like enters the controller case 55 due to the influence of the cooling air, the dust or the like falls due to the influence of gravity or the like at the time of mounting, and the dust is collected by the cooling air during the next operation. It flows to the 30 side and is discharged to the outside through the through holes 31b and 16b.

In the space (inside the container) defined by the controller case 55, in addition to the circuit board 50, a sensor board 61 on which the rotation position detection element 62 is mounted is further provided. The sensor board 61 is arranged so as to be orthogonal to the rotation axis direction of the motor 5. A switch 52 for switching on or off of the motor 5 is provided on the rear side of the sensor board 61. A slide bar 54 for transmitting the operation of the switch lever 53 (see FIG. 2 to be described later) to the switch 52 is connected to the switch 52.

The bearing holder 23 of the motor housing 2 holds the bearing 14a and serves as a fixing portion for screwing the controller case 55. Further, the cooling air is sent from the internal space on the rear cover 3 side to the internal space inside the motor housing 2. It becomes the forming part of the air passage to flow into. The bearing holder 23 is integrally molded with synthetic resin and is molded at the same time as the other motor housing 2. At the time of this molding, the bearing 14a is inserted, the mold is closed, the mold is filled with resin, the mold is opened, and the resin component (motor housing 2) is taken out. In this way, insert molding does not incorporate the metal component (bearing 14a) into the resin component (motor housing 2) after molding, but incorporates the metal component (insert bearing 14a) into the mold in advance (positioning). Then, the motor housing 2 is molded by filling with resin. As a result, secondary processing for incorporating the metal part after molding of the resin part becomes unnecessary, and a durable assembly in which the metal and the resin are integrated can be realized. Further, since the bearing 14a can be accurately arranged with respect to the motor housing 2, the centering of the rotary axis A1 becomes easy, and the deceleration mechanism using the motor 5 and the first and second bevel gears (19, 33) Improvement of rotation accuracy can be expected. Further, since the shape of the bearing 14a is not easily affected by the shape of the motor 5, the outer diameter of the bearing 14a can be made larger than the outer diameter of the rotor 6 or the inner diameter of the stator 8, for example.

The bearing 14a is fixed in a centered state with respect to the rotation axis A1 by being insert-molded into the bearing holding portion 20 of the motor housing 2. A labyrinth mechanism 40 for the bearing 14a is provided on the front side of the bearing 14a. The labyrinth mechanism 40 is a minute gap formed so that the rotating portion (here, the rotating shaft 9 and the rotor 6) and the non-rotating portion (inner wall surface of the motor housing 2) are bent in a continuous manner, and is air. Due to the resistance when flowing through a narrow gap, the flow of air mixed with dust from the accommodation space side of the motor 5 to the bearing 14a is greatly restricted. The labyrinth mechanism 40 is formed by two labyrinth members, a labyrinth rotating portion (labyrinth rotating member) 41 that rotates integrally with the rotating shaft 9, and a labyrinth fixing portion 25 that is integrally formed with the motor housing 2. The labyrinth rotating portion 41 is made of synthetic resin and is fixed to the outer peripheral side of the rotating shaft 9. The labyrinth fixing portion 25 is a wall member integrally formed with the motor housing 2, and a concave portion and a convex portion corresponding to the shape of the labyrinth rotating portion 41 are formed. The shape of the labyrinth mechanism 40 will be described later with reference to FIGS. 2 and 3.

FIG. 2 is a front view of the motor housing 2 before incorporating the motor 5 into the motor housing 2 as viewed from the opening surface side (front side). The gear case 30 is connected to the front of the paper in FIG. 2. In this state, the bearing 14a is already cast. Here, by imparting diagonal grid-like hatching to a portion of the motor housing 2 that is not the wall surface, a space (openings 27a to 27d) through which the cooling air indicated by the black arrow in FIG. 1 passes is shown. Screw holes 29a to 29d for fixing the gear case 30 with screws (not shown) are formed at four of the openings 27a to 27d separated by 90 degrees in the circumferential direction.

As can be seen by comparing FIGS. 1 and 2, the motor housing 2 has an opening 2a joined to the gear case 30 on the front side, and a taper whose outer diameter is narrowed down from the vicinity of the rear of the cooling fan 15 (see FIG. 1). The surface 21 is formed, and the vicinity of the inside of the tapered surface 21 is connected to the motor outer cylinder portion 22 facing the outer peripheral surface of the stator 8 of the motor 5 with a slight gap. A bearing holder 23 (cylindrical portion) for fixing the bearing 14a is formed inside the motor outer cylinder portion 22. The bearing holder 23 is a solid portion of synthetic resin formed so as to cover the outer peripheral side of the bearing 14a. A labyrinth fixing portion 25 is formed on the front side of the bearing holder 23. The labyrinth fixing portion 25 is formed by a recess 25a that is recessed rearward and a cylindrical portion 25b that forms the inner peripheral side wall surface of the recess 25a. The shapes of the recess 25a and the cylindrical portion 25b will be described later with reference to FIG. The labyrinth fixing portion 25 is a wall portion extending inward in the radial direction from the inner wall. The labyrinth fixing portion 25 has a vertical wall portion (corresponding to the bottom portion of the recess 25a) whose one end side is connected to the inner wall of the motor housing 2 (bearing holding portion 20) and extends inward in the radial direction, and the other end of the vertical wall portion. It has a side wall portion (corresponding to a cylindrical portion 25b) that is connected to the portion and extends in the front-rear direction (axis A1 direction). The inside of the bearing 14a is a space through which the rotating shaft 9 penetrates, but since the rotating shaft 9 is not shown in FIG. 2, diagonal grid-like hatching is provided as an opening penetrating to the rear side. The labyrinth fixing portion 25 restricts the forward movement of the bearing 14a. The labyrinth fixing portion 25 is a part of the motor housing 2. The labyrinth fixing portion 25 corresponds to the positioning member in the present invention.

The substantially cylindrical outer peripheral surface of the bearing holder 23 and the motor outer cylinder portion 22 are connected by six columns 24a to 24f extending substantially radially. Between each column 24a to 24f is a passage for cooling air sucked by the cooling fan 15. Screw holes 28a and 28b for screwing the controller case 55 from the rear side are formed in the support column 24a and the support column 24d. The circumferences of the screw holes 28a and 28b of the columns 24a and 24d are formed in a cylindrical shape having an axis parallel to the rotation axis A1 so as to have a predetermined wall thickness. A plurality of ribs 22a and the like are formed inside the cylindrical surface of the motor outer cylinder portion 22. These ribs 22a and the like are formed integrally with the motor housing 2 and are formed to hold the stator core 8a of the motor 5.

FIG. 3 is a partially enlarged view of the grinder 1 in FIG. 1 in the vicinity of the labyrinth mechanism 40. The bearing holder 23 is a cylindrical portion of synthetic resin formed so as to cover the outer peripheral side of the bearing 14a. The cross section of FIG. 3 (AA cross section of FIG. 2) is a vertical cross section passing through the center of the columns 24a and 28b (see FIG. 2 for reference numerals) and the screw holes 28a and 28b. The labyrinth mechanism 40 of this embodiment is formed by a labyrinth rotating portion 41 that rotates integrally with the rotating shaft 9 and a labyrinth fixing portion 25 that is integrally formed with the motor housing 2. The labyrinth rotating portion 41 is provided on the rear side of the rotor core 6a and behind the balancer 11b. The rotor 6 is composed of a rotor core 6a and a permanent magnet 7 inserted in a slot portion elongated in the axis A1 direction provided in the rotor core 6a. A shaft mold 10 made of a non-conductor (insulator) such as resin is formed over the entire circumference of the outer peripheral surface of the rotating shaft 9 from the range where the rotor core 6a is provided to the inner portion of the labyrinth rotating portion 41. 9 and the rotor core 6a manufactured by the laminated iron core are insulated from each other. A shaft mold 10 is not provided on the outer peripheral portion of the rotating shaft 9 in contact with the bearing 14a for the purpose of accurately centering the rotating shaft 9 and suppressing shaft shake. Further, on the rear side of the shaft mold 10, the position of the rear end of the resin at the time of molding is defined by the flange portion 9a of the rotating shaft 9 partially formed to have a large diameter.

The labyrinth rotating portion 41 is a member manufactured by integrally molding a synthetic resin, and is press-fitted into the rotating shaft 9. The labyrinth rotating portion 41 and the rotating shaft 9 may be fixed not only by press fitting but also by other methods so as not to rotate. The labyrinth rotating portion 41 includes an inner cylinder portion 42 in contact with the outer peripheral surface to which the shaft mold 10 of the rotating shaft 9 is added, and an outer cylinder portion 44 arranged radially outward with a predetermined distance from the inner cylinder portion 42. It is composed of an annular portion 43 connecting the vicinity of the middle between the inner cylinder portion 42 and the outer cylinder portion 44.

The labyrinth fixing portion 25 is composed of a concave portion 25a that is recessed in a concave shape and a cylindrical portion 25b. The wall portion on the rear side of the recess 25a comes into contact with a part of the front side surface of the bearing 14a, that is, the front surface of the outer ring, and protrudes inward from the outer peripheral edge of the bearing 14a in the radial direction. The wall portion on the inner peripheral side of the recess 25a is a cylindrical portion 25b having an inner diameter substantially the same as the inner diameter of the outer ring of the bearing 14a. Here, a small gap between the outer cylinder portion 44 and the recess 25a becomes a narrowed flow path from the space in which the motor 5 is accommodated to the arrangement space of the bearing 14a, and the accommodation space on the motor 5 side and the arrangement space of the bearing 14a. It is a so-called labyrinth passage that greatly suppresses the flow of air between the spaces. Since the outer cylinder portion 44 and the recess 25a, which are the cylinder portions, are kept in a state of not in contact with each other, the rotation of the rotor 6 is not hindered. The rear wall surface and the cylindrical portion 25b forming the recess 25a are formed at the time of integral molding of the motor housing 2. At that time, the bearing 14a is fixed by casting. A step portion 23a is continuously formed on the outer peripheral surface on the rear side of the bearing 14a in the circumferential direction. The rear end position of the inner cylinder portion 42 of the labyrinth rotating portion 41 may be further extended rearward in order to bring the rear end of the inner cylinder portion 42 into contact with the inner ring of the bearing 14a. This is because the labyrinth rotating portion 41 and the inner ring of the bearing 14a rotate at the same speed. The step portion 23a restricts the rearward movement of the bearing 14a. The step portion 23a corresponds to the positioning member in the present invention. The bearing 14a is configured so that the movement in the front-rear direction is restricted by the labyrinth fixing portion (wall portion) 25 and the step portion 23a which are a part of the motor housing 2 (housing).

A sensor magnet 63 is fixed to the rear end of the rotating shaft 9 with a screw 64. A screw hole is formed in the rotating shaft 9 for screwing the screw 64 from the rear end of the rotating shaft 9 toward the front side in the rotation axis A1 direction, and two parallel surfaces formed on the inner circumference of the sensor magnet 63. Two parallel surfaces that abut with are formed. Here, the rotor 6 fixed to the rotating shaft 9 is inserted from the front side of the motor housing 2, and after the rear end portion of the rotating shaft 9 is arranged so as to penetrate the bearing 14a, it is placed at the rear end of the rotating shaft 9. The sensor magnet 63 is screwed. After that, the controller case 55 is attached to the motor housing 2 and fixed by the screws 57a and 57b. Finally, the rear cover 3 is attached to the motor housing 2. As shown in FIG. 1, the rear cover 3 is fixed by screwing it into the screw hole of the controller case 55 from the rear end side using a screw 57c. The method of fixing the rear cover 3 and the motor housing 2 is arbitrary and is not limited to the above-mentioned fixing method.

As described above, the bearing holding structure of this embodiment makes it possible to firmly hold the bearing 14a and improve the rotation accuracy of the rotating shaft 9 of the motor 5. Further, in the first embodiment, since the bearing 14a is fixed by insert molding, a member (screw or the like) for fixing the bearing becomes unnecessary, and the assembly cost can be reduced. Further, since the labyrinth mechanism 40 (labyrinth fixing portion 25) is configured by using a part of the motor housing 2 (bearing holder 23) for fixing the bearing 14a, the dustproof performance can be significantly enhanced as compared with the conventional bearing holding mechanism. can.

FIG. 4 is a partially enlarged view of the grinder 1A according to the second embodiment of the present invention in the vicinity of the labyrinth mechanism 80. Note that the cross-sectional view of FIG. 4 is not a vertical cross-sectional view corresponding to the part AA of FIG. 2, but a horizontal cross-sectional view rotated by about 90 degrees. In the second embodiment, the bearing 14a is not insert-molded into the motor housing 2A, but is configured to be fixed to the motor housing 2A by press-fitting or inserting. The same parts as those in the first embodiment are used except for the shape of the motor housing 2A and the configuration of the labyrinth mechanism 80 part. As a procedure for assembling the bearing 14a of the second embodiment, first, the bearing 14a is press-fitted or inserted into the inner portion of the bearing holder 23 from the opening 2a on the front side of the motor housing 2A. After that, the bearing holding member 81 is attached to the front side of the bearing 14a, and the bearing holding member 81 is fixed to the motor housing 2A with two screws 83a and 83b. The bearing holding member 81 is a wall member attached separately from the motor housing 2, and the bearing holding member 81 holds only the outer ring of the bearing 14a, which is a ball bearing, in the direction of the rotation axis A1. The bearing holding member 81 has a slight gap between the bearing 14a and the inner ring when viewed in the direction of the axis A1 so as not to come into contact with the bearing holding member 81.

The bearing holding member 81 is a resin member, and the outer ring portion of the bearing 14a is fixed so as not to move forward in the axis A1 direction, and the labyrinth fixing portion 82 is provided on the inner portion in the radial direction from the holding portion of the outer ring. It is formed. The labyrinth fixing portion 82 is a stepped annular portion 82a extending inward from the outer ring of the bearing 14a and a cylindrical portion 82b. The annular portion 82a is displaced forward in the axial direction in a stepped manner so as not to interfere with the inner ring of the bearing 14a, thereby providing a gap between the annular portion 82a and the bearing 14a. A cylindrical portion 82b is formed on the front side from the inner edge portion of the annular portion 82a. The cylindrical portion 82b forms a labyrinth passage together with the labyrinth rotating member 84. The inner peripheral portion of the annular portion 82a is close to the rotation axis 9 at a minute distance. Further, the annulus front end portion of the annular portion 82a and the outer peripheral surface near the front end portion are close to the labyrinth rotating member 84 at a small distance. In this way, the bearing holding member 81 restricts the forward movement of the bearing 14a. The bearing holding member 81 becomes a part of the housing (motor housing 2A) by being attached to the motor housing 2A. The bearing holding member 81 corresponds to the positioning member in the present invention.

The labyrinth rotating material 84 is manufactured by integral molding of a synthetic resin, and is fixed to the rear surface of a brass balancer 11b by adhesion or the like. The labyrinth rotating member 84 is formed by an annular portion 84a and a cylindrical portion 84b extending radially rearward from the outer edge portion of the annular portion 84a. The inner peripheral side of the annular portion 84a is in contact with or close to the outer peripheral surface of the rotating shaft 9 on which the shaft mold 10 is applied. The length of the cylindrical portion 84b in the axial direction is determined so that there is a range in which the cylindrical portion 84b partially overlaps with the cylindrical portion 82b when viewed in the direction of the rotation axis A1. Here, a portion is formed in which the vicinity of the rear end of the cylindrical portion 84b overlaps the inner side and the outer side in the radial direction only in a small portion near the front end of the cylindrical portion 82b, but the rear end position of the cylindrical portion 84b is formed. May be further extended rearward so as to be close to the front surface of the bearing holding member 81.

As described above, according to the second embodiment, there is an advantage that the motor housing 2A can be manufactured by the same equipment as the conventional housing molding process, instead of insert molding the bearing 14a. Moreover, as compared with the conventional method of inserting the dust seal 125 into the front side of the bearing 14a, a labyrinth mechanism using the labyrinth fixing portion 82 and the labyrinth rotating material 84 is formed, so that the dustproof performance of the bearing 14a is greatly improved. be able to. Further, also in the second embodiment in which the bearing holding member 81 is used, the labyrinth rotating material 41 in the first embodiment can be used. Further, since the bearing 14a is already arranged when the motor 5 is assembled into the motor housing 2 as in the first embodiment, the shape of the bearing 14a is not easily influenced by the specifications of the motor 5, and the diameter of the bearing 14a is set to the rotor. It can be made larger than the outer diameter of 6 and the inner diameter of the stator 8.

FIG. 5 is a partially enlarged view of the bearing 14a of the grinder 1B according to the third embodiment of the present invention in the vicinity of the labyrinth mechanism 90. In the third embodiment as in the second embodiment, the bearing 14a is not insert-molded, but is mounted by press-fitting or inserting it into the motor housing 2B. However, unlike the second embodiment, the mounting direction of the bearing 14a is not from the front side (motor 5 side) of the motor housing 2B, but from the rear side (anti-motor 5 side, anti-stator 8 side). The bearing holder 23 of the motor housing 2B has an opening on the rear side so that the bearing 14a can be inserted from the rear side. A groove portion 23b adjacent to the rear end of the bearing 14a and continuous in the circumferential direction is formed in the bearing holder 23, and the bearing 14a is fixed so as not to come off to the rear side in the axis A1 direction by mounting the C ring 87 on the groove portion 23b. Will be done. The C ring 87 is sized so as to be in contact only with the outer ring of the ball bearing type bearing 14a and not with the inner ring. The C ring 87 becomes a part of the housing (motor housing 2B) by being attached to the motor housing 2B. The C ring 87 corresponds to the positioning member in the present invention.

A labyrinth mechanism 90 is provided on the front side of the bearing 14a. The labyrinth mechanism 90 is formed by a labyrinth fixing portion 95 and a labyrinth rotating portion 91. The labyrinth fixing portion 95 is formed by an annular portion 95a formed on the front side surface of the bearing holder 23 and a cylindrical portion 95b extending forward from the inner edge portion of the annular portion 95a. Both the annular portion 95a and the cylindrical portion 95b are integrally molded with the motor housing 2B. The labyrinth rotating portion 91 is a member manufactured by integrally molding a synthetic resin, and is press-fitted into the rotating shaft 9. The labyrinth rotating portion 91 includes an inner cylinder portion 92 in contact with the outer peripheral surface to which the shaft mold 10 of the rotating shaft 9 is added, and an outer cylinder portion 94 arranged radially outward with a predetermined distance from the inner cylinder portion 92. It is composed of an annular portion 93 connecting the inner cylinder portion 92 and the front end of the outer cylinder portion 94.

Although not shown in FIG. 5, a sensor magnet 63 is provided at the rear end of the rotating shaft 9 as in FIG. The space in which the sensor magnet 63 is accommodated is sealed by attaching the controller case 55. Therefore, the rear surface of the bearing 14a is not likely to be exposed to the cooling air mixed with dust. As described above, since the labyrinth fixing portion 95 is formed by integrally molding the motor housing 2 and the synthetic resin also in the third embodiment, one side of the labyrinth mechanism can be easily manufactured in any shape. Further, since the bearing 14a is mounted from the rear side, the outer diameter of the bearing 14a is not limited by the size of the inner diameter of the stator core 8a in the assembly process. Therefore, the grinder 1 by using the bearing 14a of the optimum size is used. It is possible to improve the rotation accuracy and the durability of the bearing.

FIG. 6 is a partially enlarged view of the grinder 1C in the vicinity of the labyrinth mechanism 90A according to the modified example of the third embodiment of the present invention. The basic structure is the same as the labyrinth mechanism 90 of the bearing 14a shown in FIG. 5, and the same parts are designated by the same reference numerals. The difference here is that the bearing 14C is larger in size than the bearing 14a shown in FIG. Here, a bearing 14C having a larger outer diameter _RB than the inner diameter _RS of the stator core 8a is used. That is, the relationship that the bearing 14a cannot be inserted from the front _side of the motor housing, that is, the relationship that the inner diameter _RS of the stator core 8a ≤ the outer diameter RB of the bearing 14C is realized. Even when such a large bearing 14C is used, the labyrinth fixing portion 95 can be formed in the same manner as in FIG. 5, so that the dustproof property of the large bearing 14C can be sufficiently ensured. Further, while using the first rotor 6, the rotating shaft 9, and the labyrinth rotating portion 91 shown in FIG. 5 as they are, a modified example using the large bearing 14C can be easily realized. In order to carry out this modification, it is necessary to slightly change the mold of the motor housing 2C. However, since the motor housing 2C, the large bearing 14C, and the large-diameter retaining ring 87a are only prepared and other parts are not changed, the durability of the bearing 14C can be significantly improved while suppressing an increase in manufacturing cost. The configuration in which the outer diameter RB of the bearing _14C is larger than the inner diameter _RS of the stator core 8a can be similarly applied to the other embodiments described above.

In the modified example of FIG. 6, the annular portion 95c formed by the annular portion 95a is enlarged, and the cylindrical portion 95b extending forward from the inner edge portion thereof has the same size as that of FIG. Further, the labyrinth rotating portion 91 was made the same size as that used in FIG. However, it is arbitrary to change the size of the labyrinth rotating portion 91 or change the length in the axis A1 direction. Further, in this modification, the rear end position 92a of the inner cylinder portion 92 of the labyrinth rotating portion 91 is in a non-contact state with the bearing 14C, but by further extending the rear end position of the inner cylinder portion 92 to the rear, the inner cylinder portion It may be configured so that the rear end position 92a of 92 and the inner ring of the bearing 14C are in contact with each other. This is because the inner cylinder portion 92 and the inner ring of the bearing 14C rotate at the same speed.

Although the present invention has been described above based on the examples, the present invention is not limited to the above-mentioned examples, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the grinder 1 has been used as an example of the working machine, but the present invention can be applied to any working machine as long as the motor having a rotating shaft is held by bearings. can.

1,1A, 1B, 1C ... grinder, 2,2A, 2B, 2C ... motor housing, 2a ... (front side) opening, 2b ... (rear side) opening, 3 ... rear cover, 3a ... (rear cover) opening, 5 ... Motor, 6 ... rotor, 6a ... rotor core, 7 ... permanent magnet, 8 ... stator, 8a ... stator core, 8b, 8c ... insulator, 8d ... coil, 9 ... rotating shaft, 9a ... flange part, 10 ... shaft mold, 11a, 11b ... Balancer, 14a, 14b, 14C ... Bearing, 15 ... Cooling fan, 16 ... Fan cover, 16b ... Exhaust port, 17 ... Fan guide, 18 ... Switch, 19 ... First umbrella gear, 20 ... Bearing holding part, 21 ... Tapered surface, 22 ... Motor outer cylinder part, 22a ... Rib, 23 ... Bearing holder, 23a ... Step part, 23b ... Groove part, 24a to 24f ... Support, 25 ... Labyrinth fixing part, 25a ... Recessed part, 25b ... Cylindrical part , 27a-27d ... Opening, 28a, 28b ... Screw hole, 29a-29d ... Screw hole, 30 ... Gear case, 30b ... Through hole, 31 ... Spindle, 31b ... Through hole, 32a ... Metal, 32b ... Bearing, 33 ... 2nd bearing gear, 34 ... spindle cover, 35 ... screw, 37a ... wheel washer, 37b ... wheel nut, 39 ... wheel guard, 40 ... labyrinth mechanism, 41 ... labyrinth rotating part, 42 ... inner cylinder part, 43 ... yen Ring part, 44 ... outer cylinder part, 50 ... circuit board, 52 ... switch, 53 ... switch lever, 54 ... slide bar, 55 ... controller case, 57a-57c ... screw, 58 ... power cord, 59 ... power cord holding part , 61 ... sensor board, 62 ... rotation position detection element, 63 ... sensor magnet, 64 ... screw, 65 ... grindstone, 80 ... labyrinth mechanism, 81 ... bearing holding member, 82 ... labyrinth fixing part, 82a ... annular part, 82b ... Cylindrical part, 83a, 83b ... Screw, 84 ... Labyrinth rotating material, 84a ... Circular part, 84b ... Cylindrical part, 87 ... Ring, 87a ... Stop ring, 90, 90A ... Labyrinth mechanism, 91 ... Labyrinth rotating part, 92 ... Inner cylinder part, 92a ... Rear end position (of inner cylinder part), 93 ... Circular part, 94 ... Outer cylinder part, 95 ... Labyrinth fixing part, 95a ... Circular part, 95b ... Cylindrical part, 95c ... Circular part Part, 101 ... Grinder, 102 ... Motor housing, 114a ... Bearing, 125 ... Dust seal, A1 ... (Motor) rotation axis, B1 ... (Spindle) axis

Claims (15)

It has a motor, a housing for accommodating the motor, and a bearing member that pivotally supports the motor.
The motor has a stator, and the outer diameter of the bearing member is equal to or larger than the inner diameter of the stator. The working machine according to claim 1.
The bearing member is a working machine characterized in that the housing restricts forward and backward movement in the front-rear direction. The working machine according to claim 1.
The bearing member is a working machine characterized by being insert-molded into the housing. The working machine according to claim 3.
The housing includes a resin tubular integrated motor housing.
A working machine characterized in that the bearing member is insert-molded so as to be coaxial with the central axis of the motor housing. The working machine according to claim 3 or 4.
The housing is provided with an intake port and an exhaust port.
A fan is provided on the rotating shaft of the motor.
The housing is provided with a wall portion that protrudes radially inward from the outer peripheral edge of the bearing member so as to come into contact with a part of the side surface of the bearing member, and the wall portion forms a labyrinth structure. A working machine featuring. The working machine according to claim 5.
The motor has a stator and a rotor.
The rotor is provided with a labyrinth member and is provided with a labyrinth member.
A cylindrical portion extending in the direction of the rotation axis is formed on the wall portion.
A working machine characterized in that a labyrinth structure is formed by the labyrinth member and the wall portion. The working machine according to claim 1.
A working machine characterized in that the bearing member is inserted and held from the stator side into a bearing holding portion formed in the housing. The working machine according to claim 1.
A working machine characterized in that the bearing member is inserted and held from the stator side in a bearing holding portion formed in the housing. The working machine according to claim 7.
The housing is a working machine having a positioning member on the opposite side of the bearing member to the stator side. The working machine according to claim 8.
The housing is a working machine having a positioning member on the opposite side of the bearing member to the stator side. The working machine according to claim 9 or 10.
The housing includes a resin tubular integrated motor housing.
A working machine characterized in that the positioning member is attached as a member separate from the motor housing. The working machine according to claim 1, on one end side of the bearing member, a wall member integrally formed with the housing or a wall member attached to a separate body, and a cylinder attached to a part of the motor. A working machine characterized in that a labyrinth structure is formed by a member and a member. The working machine according to claim 12.
The motor has a stator, a rotor, and a rotation axis for fixing the rotor.
A working machine characterized in that the tubular member is fixed to the rotor and / or the rotating shaft. The working machine according to claim 13.
A bearing holding portion for holding the outer ring of the bearing member is formed in the housing.
A working machine characterized in that the outer diameter of the bearing member is equal to or larger than the inner diameter of the stator. The working machine according to claim 14.
A working machine characterized in that the outer diameter of the tubular member is smaller than the outer diameter of the rotor and the outer diameter of the bearing member.

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