JP2013038926A - Thrust bearing structure and motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust bearing structure and a motor which ensure smooth rotations of a rotation shaft for a long time.SOLUTION: A thrust bearing structure includes: an adjustment screw 42 receiving a thrust load of a warm shaft 23; a ball 41 held by the warm shaft 23; and grease 43 disposed between the adjustment screw 42 and the ball 41. In the thrust bearing structure, the warm shaft 23 is rotatably supported with axial preload applied to the warm shaft 23. Further, an accumulation groove 52 is formed around a slide part 51 in the adjustment screw 42 where the ball 41 slides.

Description

  The present invention relates to a thrust bearing structure and a motor.

  2. Description of the Related Art Conventionally, there is a motor that decelerates and outputs the rotation of a drive shaft driven by a motor unit by a reduction mechanism of a reduction unit. For example, in the motor described in Patent Document 1, the speed reduction portion includes a gear housing fixed to the motor portion, and a speed reduction mechanism formed by meshing a worm shaft and a worm wheel. The drive shaft of the motor unit is connected to a worm shaft housed in the worm shaft housing portion of the gear housing so as to be integrally rotatable, and the worm shaft meshes with a worm wheel housed in the wheel housing portion of the gear housing. ing. Accordingly, for example, a window regulator that opens and closes the window glass is operated by the output gear that rotates integrally with the worm wheel.

  A ball is held at the tip of the worm shaft, and the worm shaft is accommodated in a state where a thrust load is applied to a receiving member (plate) provided in the gear housing via the ball. That is, the worm shaft is rotatably supported in a state in which an axial preload is applied by the receiving member (see Patent Document 1, FIG. 1). As a result, rattling of the worm shaft is suppressed and the generation of abnormal noise is suppressed.

JP 2004-147490 A

  Incidentally, grease for lubrication is generally interposed between the ball and the receiving member, and smooth rotation of the worm shaft is ensured. However, if the motor is used over a long period of time, there is a risk that grease between the ball and the receiving member will be insufficient and smooth rotation of the worm shaft cannot be ensured.

Such a problem may occur not only when the worm shaft is supported but also when another rotating shaft to which an axial preload is applied is supported.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a thrust bearing structure and a motor that can ensure a smooth rotation of a rotating shaft over a long period of time. .

  In order to achieve the above object, the invention described in claim 1 is directed to a thrust bearing structure that rotatably supports the rotating shaft in a state where an axial preload is applied to the rotating shaft, and receives a thrust load of the rotating shaft. A receiving member, a ball held on one of the rotating shaft and the receiving member, and a grease interposed between the other of the rotating shaft and the receiving member and the ball, The gist is that a grease reservoir is formed around the sliding portion on which the ball slides on the other side.

  According to the above configuration, since a grease reservoir for storing grease is formed around the sliding portion, the grease between the ball and the sliding portion is insufficient by supplying the grease from the grease reservoir. This can be suppressed. Thereby, smooth rotation of a rotating shaft is securable over a long period of time.

The gist of a second aspect of the present invention is the thrust bearing structure according to the first aspect, wherein the sliding portion is formed in a concave shape.
According to the above configuration, since the sliding portion is formed in a concave shape, the grease is easily taken into the sliding portion from the grease reservoir, and the grease is difficult to flow out from the sliding portion. Therefore, it can suppress more that the grease between a ball | bowl and a sliding part runs short.

  According to a third aspect of the present invention, in the thrust bearing structure according to the second aspect, the sliding portion has a flat surface perpendicular to the axial direction of the rotating shaft while the ball makes point contact. To do.

  For example, when the sliding part has a hemispherical shape, if the center of the ball does not coincide with the center of the sliding part in the axial direction of the rotation axis, the radial component force rotates from the sliding part. Acts on the shaft. In this respect, in the above configuration, since the sliding portion makes a point contact with the ball and is orthogonal to the axial direction and has a flat surface, the center of the ball does not coincide with the center of the sliding portion in the axial direction of the rotating shaft. However, it is possible to prevent a radial load from acting on the rotating shaft. Thereby, it is possible to allow the axial displacement of the rotating shaft with respect to the receiving member while further suppressing the shortage of grease between the ball and the sliding portion.

  According to a fourth aspect of the present invention, in the thrust bearing structure according to any one of the first to third aspects, a projecting portion that projects toward one of the other is the sliding portion. The gist is formed at a position where the grease reservoir is sandwiched therebetween.

  According to the above configuration, the protruding portion can suppress the grease stored in the grease reservoir from flowing out except between the ball and the sliding portion, so that the grease is insufficient between the sliding portion and the ball. It can be further suppressed.

  The invention according to claim 5 uses the thrust bearing structure according to any one of claims 1 to 4 in a state where an axial preload is applied to the rotating shaft connected to the drive shaft of the motor unit. The gist of the present invention is a motor that rotatably supports the rotating shaft. According to the said structure, the motor which can rotate a rotating shaft smoothly over a long term can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the thrust bearing structure and motor which can ensure the smooth rotation of a rotating shaft over a long term can be provided.

Sectional drawing of the motor of 1st Embodiment. The expanded sectional view showing the tip end neighborhood of the worm shaft of a 1st embodiment. The expanded sectional view which shows the front-end | tip vicinity of the worm shaft of 2nd Embodiment. The expanded sectional view which shows the front-end | tip vicinity of the worm shaft of another example.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
A motor 1 shown in FIG. 1 is used as a drive source of a power window device that raises and lowers a window glass of a vehicle, for example. As shown in the figure, the motor 1 includes a motor unit 2 that generates a rotational driving force, and a speed reducing unit 3 that decelerates and outputs the rotational driving force generated by the motor unit 2.

  The motor unit 2 includes a bottomed cylindrical yoke housing 11. A pair of magnets 12 are fixed to the inner peripheral surface of the yoke housing 11 so as to face each other. An armature 13 is disposed between the pair of magnets 12 in the yoke housing 11. The armature 13 includes a shaft-shaped drive shaft 14 disposed in the central portion of the yoke housing 11, and a cylindrical commutator is provided at a tip side (lower side in FIG. 1) of the drive shaft 14. 15 is fixed.

  A flange portion 11 a extending outward is formed at the opening of the yoke housing 11. A brush holder 16 made of an insulating resin material is fixed to the opening of the yoke housing 11. The brush holder 16 has a holding portion 16 a that holds a pair of brushes 17 that are in sliding contact with the commutator 15. Each brush 17 is electrically connected to a connector portion 18 provided on the side of the motor portion 2 via a power supply line (not shown). The brush holder 16 is provided with a bearing 19, and the drive shaft 14 is rotatably supported by the bearing 19 and a bearing (not shown) provided at the center of the bottom of the yoke housing 11.

  The speed reduction unit 3 includes a resin gear housing 21, a worm shaft 23 coupled to the drive shaft 14 of the armature 13 via a clutch 22, and a speed reduction mechanism 25 including a worm wheel 24 meshing with the worm shaft 23. ing.

  The gear housing 21 is fixed to the flange portion 11 a of the yoke housing 11 with a plurality of screws 27. The gear housing 21 is formed with a worm shaft housing portion 31 extending along the axial direction of the drive shaft 14 and a wheel housing portion 32 connected to the worm shaft housing portion 31 so as to be connected to the inside of the yoke housing 11. The worm shaft 23 is connected to the drive shaft 14 via the clutch 22 so as to be integrally rotatable, and is rotatably accommodated in the worm shaft accommodating portion 31 via a pair of bearings 33a and 33b. The clutch 22 is configured to transmit the rotational motion from the drive shaft 14 side to the worm shaft 23 while not transmitting the rotational motion from the worm shaft 23 side to the drive shaft 14.

  The worm wheel 24 is rotatably accommodated in the wheel accommodating portion 32. An output shaft 35 that protrudes to the outside of the gear housing 21 is provided at the center of the worm wheel 24 so as to be able to rotate integrally with the worm wheel 24. The output shaft 35 is connected to a known window regulator (not shown) for raising and lowering the window glass of the vehicle.

  In the motor 1 configured as described above, when a current is supplied to the armature 13 from the connector portion 18 connected to the external power source via the brush 17, the drive shaft 14 is rotationally driven together with the armature 13, and the same drive is performed. The rotation of the shaft 14 is transmitted to the worm shaft 23. The rotation transmitted to the worm shaft 23 is decelerated via the worm wheel 24 and output from the output shaft 35. Thereby, the window regulator connected to the output shaft 35 is operated, and the window glass is raised or lowered according to the rotation direction of the output shaft 35.

  Here, a ball 41 is held at the tip of the worm shaft 23, and the worm shaft 23 applies a predetermined thrust load to an adjustment screw 42 as a receiving member provided in the gear housing 21 via the ball 41. Thus, it is accommodated in the worm shaft accommodating portion 31. That is, the worm shaft 23 is rotatably supported in a state where the axial preload is applied by the adjustment screw 42. Further, as shown in FIG. 2, lubricating grease 43 is interposed between the ball 41 and the adjusting screw 42.

  More specifically, a substantially cylindrical housing recess 45 is formed at the tip of the worm shaft 23. The ball 41 formed in a spherical shape is housed in the housing recess 45 in such a manner as to partially protrude from the housing recess 45. The ball 41 is held in the housing recess 45 by caulking a part of the opening end of the housing recess 45. A flat thrust plate 46 is interposed between the ball 41 and the bottom surface of the housing recess 45.

  On the other hand, a screw hole 47 is formed in the worm shaft housing portion 31 at a position facing the tip (housing recess 45) of the worm shaft 23 in the axial direction of the worm shaft 23. The screw hole 47 is formed so that the adjustment screw 42 is arranged coaxially with the worm shaft 23, and the ball 41 slides on the central portion of the adjustment screw 42. The adjustment screw 42 is screwed into the screw hole 47 and is fixed to the gear housing 21 by a lock nut 48 (see FIG. 1) being screwed into an outer end protruding outside the gear housing 21. Has been. The amount of preload (thrust load of the worm shaft 24) applied to the worm shaft 23 can be adjusted by changing the amount of protrusion of the adjustment screw 42 into the worm shaft housing portion 31.

  A storage groove 52 serving as a grease reservoir capable of storing the grease 43 is recessed around the sliding portion 51 where the ball 41 slides at the inner end of the adjustment screw 42. In the present embodiment, the storage groove 52 is formed in an annular shape centering on the axis of the adjustment screw 42. The sliding portion 51 is formed in a flat shape orthogonal to the axial direction of the worm shaft 23.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) Since the storage groove 52 is formed around the sliding portion 51 on which the ball 41 slides in the adjustment screw 42, the grease 41 is supplied from the storage groove 52, so that the ball 41 and the sliding portion 51 It can suppress that the grease 43 in between is insufficient. Thereby, smooth rotation of the worm shaft 23 can be ensured over a long period of time, and the motor 1 excellent in quietness can be provided.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. The main difference between the present embodiment and the first embodiment is only the thrust bearing structure of the worm shaft. For this reason, for convenience of explanation, the same components are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

  As shown in FIG. 3, the sliding part 51 of the adjusting screw 42 is formed in a concave shape. Specifically, the sliding portion 51 is a substantially hemispherical concave concave curved surface 61 having a radius of curvature larger than the radius of curvature of the ball 41, and a flat plane that is disposed at the center of the concave curved surface 61 and orthogonal to the axial direction. And a flat surface 62 having a shape. The ball 41 is formed so as to make point contact with the flat surface 62.

  An annular projecting portion 63 projecting toward the worm shaft 23 side is formed on the outer peripheral side of the storage groove 52 in the adjustment screw 42. That is, the protruding portion 63 is formed at a position where the storage groove 52 is sandwiched between the protruding portion 63 and the sliding portion 51.

As described above, according to this embodiment, in addition to the effect (1) of the first embodiment, the following effect can be obtained.
(2) Since the sliding portion 51 is formed in a concave shape, the grease 43 is easily taken into the sliding portion 51 from the storage groove 52 and the grease 43 is difficult to flow out from the sliding portion 51. Therefore, it is possible to further suppress the grease 43 between the ball 41 and the sliding portion 51 from being insufficient. Thereby, the axial displacement of the worm shaft 23 relative to the adjusting screw 42 can be allowed while further suppressing the shortage of the grease 43 between the ball 41 and the sliding portion 51.

  (3) A flat surface 62 that is in point contact with the ball 41 and orthogonal to the axial direction is formed on the sliding portion 51. Here, for example, when the sliding portion 51 has a hemispherical concave shape, the sliding portion 51 must be aligned with the center of the ball 41 and the center of the sliding portion 51 in the axial direction of the worm shaft 23. The component force in the radial direction from 51 acts on the worm shaft 23. In this regard, in the above configuration, since the sliding portion 51 has the flat surface 62, even if the center of the ball 41 and the center of the sliding portion 51 do not coincide with each other in the axial direction of the worm shaft 23, It is possible to prevent the component force from acting.

  (4) An annular projecting portion 63 projecting toward the worm shaft 23 is formed at a position where the storage groove 52 is sandwiched between the adjusting screw 42 and the sliding portion 51. Since the protruding portion 63 can prevent the grease 43 stored in the storage groove 52 from flowing out except between the ball 41 and the sliding portion 51, the grease 43 is insufficient between the sliding portion 51 and the ball 41. This can be further suppressed.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
-In the said 1st Embodiment, you may form a protrusion as shown to the said 2nd Embodiment in the outer peripheral side of the storage groove | channel 52 in the adjustment screw 42. FIG. Moreover, in the said 2nd Embodiment, the protrusion part 63 does not need to be formed. Note that the protrusions 63 do not have to be in an annular shape, and may be formed, for example, in a protruding shape and arranged at predetermined intervals in the circumferential direction of the adjustment screw 42.

  -In the said 2nd Embodiment, although the sliding part 51 was formed in the concave shape which has the concave curved surface 61 and the flat surface 62, it is not restricted to this, For example, as shown in FIG. It may be formed. In the example shown in FIG. 4, the protrusion 63 is not formed on the adjustment screw 42. Further, the concave curved surface 61 may be formed so that the curvature radius is smaller than the curvature radius of the ball 41. Even if comprised in this way, there can exist an effect similar to (2) of the said 2nd Embodiment.

In the first embodiment, the sliding portion 51 has a flat shape, and in the second embodiment, the sliding portion 51 has a concave shape. However, the present invention is not limited to this, and the sliding portion 51 may have a convex shape. .
In each of the above embodiments, the grease reservoir is configured by the annular storage groove 52. However, the grease reservoir is not limited thereto, and the grease reservoir is configured by a plurality of storage recesses formed at predetermined intervals in the circumferential direction of the adjustment screw 42, for example. May be.

  In each of the above embodiments, the ball 41 is held on the worm shaft 23 and the storage groove 52 as a grease reservoir is formed on the adjustment screw 42. However, the invention is not limited to this, and a storage groove is formed on the worm shaft 23 and the adjustment screw 42 may hold the ball 41.

  In each of the above embodiments, the worm shaft 23 is applied with a preload from the adjusting screw 42 as a receiving member. However, the present invention is not limited thereto, and for example, a flat plate may be fixed at a position facing the tip of the worm shaft 23 in the worm shaft housing portion 31, and preload may be applied from the plate or the like.

  In each of the above embodiments, the motor of the present invention is applied to the drive source of the power window device. However, the present invention is not limited to this, and is applied to, for example, the drive source of an electric tilt device that adjusts the height position of the steering wheel electrically. May be.

  In each of the above embodiments, the thrust bearing structure of the present invention is used to rotatably support the worm shaft 23 in a state where an axial preload is applied to the worm shaft 23. Alternatively, the rotary shaft may be rotatably supported in a state where an axial preload is applied to the rotary shaft provided with a pulley or the like.

  DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Motor part, 3 ... Deceleration part, 14 ... Drive shaft, 21 ... Gear housing, 23 ... Worm shaft as a rotating shaft, 24 ... Worm wheel, 41 ... Ball, 42 ... Adjustment screw as receiving member , 43 ... grease, 51 ... sliding part, 52 ... storage groove as a grease reservoir, 61 ... concave curved surface, 62 ... flat surface, 63 ... projecting part.

Claims (5)

In a thrust bearing structure that rotatably supports the rotary shaft in a state where an axial preload is applied to the rotary shaft,
A receiving member for receiving a thrust load of the rotating shaft;
A ball held on one of the rotating shaft and the receiving member;
Comprising either one of the rotating shaft and the receiving member and grease interposed between the balls;
A thrust bearing structure, wherein a grease reservoir is formed around a sliding portion on which the ball slides on either one of the other. The thrust bearing structure according to claim 1,
A thrust bearing structure, wherein the sliding portion is formed in a concave shape. The thrust bearing structure according to claim 2,
The thrust bearing structure according to claim 1, wherein the sliding portion has a flat surface that makes point contact with the ball and is orthogonal to the axial direction of the rotating shaft. In the thrust bearing structure according to any one of claims 1 to 3,
The thrust bearing structure according to any one of claims 1 to 6, wherein a protrusion protruding toward one of the other is formed at a position where the grease reservoir is sandwiched between the protrusion and the sliding portion.   Using the thrust bearing structure according to any one of claims 1 to 4, the rotary shaft is rotatably supported in a state where an axial preload is applied to the rotary shaft connected to the drive shaft of the motor unit. A motor characterized by that.

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