JP2021089035A - Shaft supporting structure of speed reducer and steering device - Google Patents

Abstract

To reduce the noise of a speed reducer.SOLUTION: A shaft supporting structure 101 of a speed reducer 100 is equipped with a first bearing 4 rotatably supporting a base end side of a worm shaft 2, a second bearing 11 rotatably supporting a tip end side of the worm shaft 2, and a coil spring 12 energizing the worm shaft 2 toward a worm wheel 1 through the second bearing 11. The first bearing 4 has an inner ring 142 having an inside raceway groove 142a, an outer ring 141 having an outside raceway groove 141a, and a plurality of balls 143 disposed between the inside raceway groove 142a and the outside raceway groove 141a. The shaft supporting structure 101 is further equipped with pressing means for pressing a part of the outer ring 141 in an axial direction of the worm shaft 2.SELECTED DRAWING: Figure 4

Description

The present invention relates to a shaft support structure of a speed reducer and a steering device.

A steering device including a worm reducer is known (see Patent Document 1). The worm reducer includes a worm shaft that is rotationally driven by a drive source such as an electric motor, and a worm wheel that meshes with the worm shaft. Both ends of the worm shaft are rotatably supported by bearings.

Japanese Unexamined Patent Publication No. 2016-3760

In such a worm reducer, the base end portion of the worm shaft is swingably connected to the rotating shaft of the electric motor, and the tip end portion of the worm shaft is urged toward the worm wheel side by an urging member. The bearing that supports the base end of the worm shaft is provided with an internal gap so that the inner ring can swing with respect to the outer ring. Since the bearing is provided with an internal gap in this way, when an axial force acts on the worm shaft, the inner ring moves slightly in the axial direction together with the worm shaft, so that the rolling element (ball) becomes the outer ring. Alternatively, it may collide with the inner ring and generate noise (collision noise).

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the noise of the speed reducer.

The present invention has a shaft support structure for a speed reducer, and has a first bearing that rotatably supports the base end side of the drive gear shaft, a second bearing that rotatably supports the tip end side of the drive gear shaft, and the like. The first bearing includes an inner ring having an inner raceway groove, an outer ring having an outer raceway groove, and an inner raceway groove. It has a plurality of rolling elements arranged between the outer raceway groove and the outer raceway groove, and the shaft support structure is further provided with a pressing means for pressing a part of the outer ring in the axial direction of the drive gear shaft. ..

In the present invention, a part of the outer ring of the first bearing that supports the base end side of the drive gear shaft is pressed in the axial direction of the drive gear shaft by the pressing means, so that the drive gear shaft swings toward the driven gear. The internal gap of the first bearing in the axial direction of the drive gear shaft can be partially reduced while ensuring the internal gap of the first bearing in the above. As a result, while allowing the drive gear shaft to swing toward the driven gear, it is possible to prevent the inner ring of the first bearing from moving in the axial direction together with the drive gear shaft when an axial force is applied to the drive gear shaft. it can.

The present invention is characterized in that the pressing means presses the outer ring at positions separated by 180 degrees.

In the present invention, it is possible to control the direction in which the inner ring is likely to tilt as compared with the case where only one point is pressed, and it is possible to prevent the drive gear shaft from swinging in an unintended direction other than the swinging direction.

The present invention is characterized in that the pressing means presses the outer ring from both sides in the axial direction of the drive gear shaft.

In the present invention, since the outer ring is pressed from both sides in the axial direction of the first bearing, the amount of deformation of the outer ring is uniform on both sides in the axial direction, and rotation failure of the first bearing is prevented.

The present invention is characterized in that the pressing means has an annular member having a protrusion formed so as to be pressed against the outer ring in the axial direction of the drive gear shaft.

In the present invention, the protrusion of the annular member can press the desired position of the outer ring.

The present invention is characterized in that the pressing means has a protrusion formed on the outer ring and receiving an external force in the axial direction of the drive gear shaft.

In the present invention, since the protrusion as the pressing means is formed on the outer ring, the number of parts can be reduced.

The present invention is a steering device, a speed reducer having a shaft support structure of the speed reducer, a drive gear shaft supported by the shaft support structure, and a driven gear that meshes with the drive gear shaft, and an electric motor as a drive source. The driven gear is provided on the output shaft that transmits the rotational force of the electric motor to the rack shaft that steers the wheels, and the reduction gear reduces the rotation of the drive gear shaft and transmits it to the driven gear. It is characterized by that.

INDUSTRIAL APPLICABILITY The present invention can provide a steering device including a speed reducer having low noise.

According to the present invention, the noise of the speed reducer can be reduced.

It is a block diagram of the steering apparatus which concerns on embodiment of this invention. It is sectional drawing of the steering apparatus which concerns on embodiment of this invention. It is sectional drawing of the 1st bearing of the steering apparatus which concerns on embodiment of this invention, (a) shows the state which the inner ring is not tilted with respect to the outer ring, (b) is the state which the inner ring is tilted with respect to the outer ring. Indicates the state. It is a perspective view of the outer ring, the washer, and the locknut of the 1st bearing of the steering apparatus which concerns on embodiment of this invention. It is a schematic view of the cross section perpendicular to the swing direction through the central axis of the 1st bearing of the steering apparatus which concerns on embodiment of this invention, and shows the state which the washer and the locknut pressed the outer ring of the 1st bearing. It is a perspective view of the 1st bearing which concerns on the modification of embodiment of this invention.

A steering device including a speed reducer according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the power steering device 10 mounted on the vehicle and assisting the steering force applied to the steering wheel by the driver will be described as the steering device.

As shown in FIGS. 1 and 2, the power steering device 10 includes a speed reducer 100 and an electric motor 7 as a drive source. The speed reducer 100 meshes with the worm shaft 2 as a drive gear shaft connected to the output shaft 7a of the electric motor 7 and rotating with the drive of the electric motor 7 and the worm 2a as a drive gear formed on the worm shaft 2. It includes a worm wheel 1 as a driven gear, a gear case 3 for accommodating the worm shaft 2 and the worm wheel 1, and a shaft support structure 101 for supporting the worm shaft 2. The worm shaft 2 and the output shaft 7a of the electric motor 7 are connected by a shaft coupler 19 that allows shaft misalignment.

A steering shaft 20 is connected to the steering handle 16, and the steering shaft 20 rotates as the steering handle 16 rotates. The steering shaft 20 includes an input shaft 21 linked to the steering handle 16, an output shaft 22 linked to the rack shaft 8, and a torsion bar 23 connecting the input shaft 21 and the output shaft 22. The worm wheel 1 is provided on the output shaft 22.

The power steering device 10 includes a torque sensor 24 that detects the steering torque acting on the torsion bar 23 due to the relative rotation of the input shaft 21 and the output shaft 22 accompanying the steering operation by the driver, and the steering detected by the torque sensor 24. A controller 25 that controls the drive of the electric motor 7 based on the torque is further provided. The torque output from the electric motor 7 is transmitted from the worm shaft 2 to the worm wheel 1 and is applied to the output shaft 22 as an assist torque. In this way, the power steering device 10 assists the driver in steering operation by controlling the drive of the electric motor 7 by the controller 25 based on the detection result of the torque sensor 24.

When the worm shaft 2 rotates with the drive of the electric motor 7, the speed reducer 100 reduces the rotation of the worm shaft 2 and transmits the rotation to the worm wheel 1. As a result, the output shaft 22 on which the worm wheel 1 is provided rotates, and the rotational force of the electric motor 7 is transmitted to the rack shaft 8 that steers the wheel 6.

As shown in FIG. 2, the worm shaft 2 is housed in a metal gear case 3, and the electric motor 7 is attached to the gear case 3. The worm 2a is formed with a tooth portion 2e that meshes with the tooth portion 1a of the worm wheel 1. An opening 3c is formed in the gear case 3 at a position corresponding to the tooth portion 2e, and the tooth portion 2e of the worm 2a and the tooth portion 1a of the worm wheel 1 mesh with each other through the opening 3c.

The shaft support structure 101 of the speed reducer 100 has a first bearing 4 that rotatably supports the base end side (electric motor 7 side) of the worm shaft 2 and a tip side (opposite side of the electric motor 7 side) of the worm shaft 2. ) Is rotatably supported, and a coil spring 12 as an urging member that urges the worm shaft 2 toward the worm wheel 1 via the second bearing 11. The worm shaft 2 is rotatably supported in the gear case 3 by a pair of bearings (first bearing 4 and second bearing 11). The axial direction (central axial direction) of the worm shaft 2 is also simply referred to as the axial direction (D3).

The first bearing 4 is a deep groove ball bearing in which a ball 143 as a rolling element is interposed between an annular outer ring 141 and an inner ring 142. The first bearing 4 is housed in a housing hole 130 provided in the gear case 3. The outer ring 141 of the first bearing 4 is sandwiched in the axial direction (D3) between the step portion 3a formed in the gear case 3 and the locknut 32 fastened in the gear case 3 via a washer 31. Details of the washer 31 and the locknut 32 will be described later. The inner ring 142 of the first bearing 4 is fixed by being press-fitted into the worm shaft 2. The inner ring 142 is sandwiched in the axial direction (D3) between the step portion 2b of the worm shaft 2 and the worm side joint 9 of the shaft coupler 19 which is press-fitted into the end portion of the worm shaft 2.

The first bearing 4 has an internal gap 144 (see FIG. 3) for allowing the worm shaft 2 to swing toward the worm wheel 1. The direction in which the worm shaft 2 swings around the first bearing 4 is referred to as the swing direction (D1). Details of the first bearing 4 will be described later.

The second bearing 11 is a deep groove ball bearing in which a ball as a rolling element is interposed between an annular outer ring and an inner ring. The second bearing 11 is housed in the bottom of the gear case 3. The inner ring of the second bearing 11 is locked to the step portion 2c formed near the tip end portion of the worm shaft 2.

A flange portion 17 is formed so as to project from the outer peripheral surface of the gear case 3. A through hole 13 is formed in the flange portion 17 so as to face the outer peripheral surface of the second bearing 11. The opening of the through hole 13 that opens to the end surface 17a of the flange portion 17 is closed by the lid member 14.

The coil spring 12 is housed in the through hole 13 in a compressed state between the tip surface of the lid member 14 and the outer peripheral surface of the second bearing 11. The coil spring 12 urges the second bearing 11 in the direction in which the gap between the tooth portion 2e of the worm 2a and the tooth portion 1a of the worm wheel 1 becomes smaller, that is, in the direction in which the worm 2a meshes with the worm wheel 1.

The inner peripheral surface 3b surrounding the outer peripheral surface of the second bearing 11 in the gear case 3 has a pair of flat surfaces parallel to each other so that the second bearing 11 can move toward the worm wheel 1 by the urging force of the coil spring 12. It is formed in the shape of an elongated hole. The inner peripheral surface 3b may have any shape as long as the second bearing 11 can move inside the inner peripheral surface 3b. For example, the inner peripheral surface 3b may have a round hole shape whose inner diameter is larger than the outer diameter of the second bearing 11, and it is not necessary that a pair of flat surfaces parallel to each other are formed.

At the initial stage when the assembly of the worm shaft 2 into the gear case 3 is completed, the second bearing 11 is urged toward the worm wheel 1 by the urging force of the coil spring 12, and the backlash between the worm 2a and the worm wheel 1 There will be no (gap). In this state, the worm shaft 2 is tilted with the first bearing 4 as a fulcrum due to the urging force of the coil spring 12.

When the worm 2a and the tooth portions 1a and 2e of the worm wheel 1 are worn as the power steering device 10 is driven, the second bearing 11 moves in the elongated hole of the gear case 3 due to the urging force of the coil spring 12, and the worm shaft. The backlash of the tooth portions 1a and 2e of 2 and the worm wheel 1 is reduced. Therefore, in order for the backlash to be stably reduced, it is necessary for the worm shaft 2 to swing smoothly toward the worm wheel 1.

As shown in FIGS. 3A and 3B, in the first bearing 4, the inner ring 142 fixed to the worm shaft 2 can swing with respect to the outer ring 141 fixed to the gear case 3. An internal gap 144 is provided. In addition, in FIGS. 3A and 3B, the inner diameter of the inner ring 142 of the first bearing 4 is described smaller than that shown in FIG. 2, and the internal gap 144 is exaggerated and described larger. ..

If an internal gap 144 is provided over the entire circumference of the first bearing 4, when a force in the axial direction (D3) acts on the worm shaft 2, the inner ring 142 is slightly axially (D3) together with the worm shaft 2. May move. Therefore, for example, when a force in the axial direction (D3) is applied from the electric motor 7 to the worm shaft 2 during turning back steering, the ball 143 collides with the outer ring 141 or the inner ring 142, and noise (collision noise) is generated. There is a risk. Further, when an axial force (D3) is applied from the road surface to the worm shaft 2 from the worm wheel 1 via the wheel 6, the rack shaft 8, the output shaft 22, etc., noise (collision noise) may be generated in the same manner. There is also.

Therefore, in the present embodiment, in order to allow the worm shaft 2 to swing smoothly and to prevent the generation of collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, the outer ring of the first bearing 4 is prevented from being generated. By partially deforming 141, the size of the internal gap 144 of the first bearing 4 is made different in the circumferential direction. In the present embodiment, at the position of the first bearing 4 in the swing direction (D1), an internal gap 144 having a predetermined length X (see FIG. 3) is secured in the swing direction (D1). On the other hand, as shown in FIG. 5, the internal gap 144 becomes smaller at the position in the orthogonal direction (D2) orthogonal to the swing direction (D1) of the first bearing 4 and the axial direction (D3) of the worm shaft 2. I did it. Specifically, the internal gap 144 is set to 0 or almost 0 in the axial direction (D3) of the worm shaft 2. In this way, the internal gap 144 is partially reduced in the circumferential direction of the first bearing 4. As a result, when the worm shaft 2 allows the worm shaft 2 to swing toward the worm wheel 1 and an axial (D3) force acts on the worm shaft 2, the inner ring 142 of the first bearing 4 moves in the axial direction (with the worm shaft 2). It is possible to suppress the movement to D3).

The support structure of the first bearing 4 will be described in detail with reference to FIGS. 2 to 5. FIG. 4 is a perspective view of the first bearing 4, the washer 31, and the locknut 32. FIG. 5 is a schematic view of a cross section perpendicular to the swing direction (D1) through the central axis of the first bearing 4 in a state where the locknut 32 presses the outer ring 141 of the first bearing 4 via the washer 31. ..

As shown in FIGS. 2 and 4, the shaft support structure 101 of the speed reducer 100 has a washer 31 and a locknut as pressing means for pressing a part of the outer ring 141 of the first bearing 4 in the axial direction (D3) of the worm shaft 2. 32 is further provided. The washer 31 is an annular member formed concentrically with the outer ring 141. A pressing protrusion 31a capable of pressing the outer ring 141 is formed on the end surface of the washer 31 at positions separated by 180 degrees, and the outer peripheral surface of the washer 31 is positioned to determine the position of the washer 31 in the circumferential direction with respect to the gear case 3. The protrusion 31b is formed. The washer 31 is a first bearing in a state where the pressing protrusion 31a faces the end surface of the outer ring 141 and is located in the orthogonal direction (D2) orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2. It is sandwiched between the 4 and the locknut 32 and accommodated in the accommodating hole 130 of the gear case 3. At this time, by accommodating the positioning protrusion 31b in a notch (not shown) provided in the gear case 3, the washer 31 is positioned with respect to the gear case 3 in the circumferential direction.

The washer 31 is housed in the accommodating hole 130, and by screwing and fixing the locknut 32 to the inner peripheral surface of the accommodating hole 130, an axial force is received from the locknut 32 to the outer ring 141 of the first bearing 4. On the other hand, the worm shaft 2 is pressed in the axial direction (D3). As a result, the pressing projection 31a of the washer 31 presses the outer ring 141 of the first bearing 4 in the axial direction (D3) of the worm shaft 2. The pressing protrusions 31a are 180 degrees apart from each other in the orthogonal direction (D2) orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2, respectively, and the outer ring 141 is placed in the axial direction of the worm shaft 2 (D3). Press on D3). In the following, the position pressed by the pressing projection 31a of the washer 31 on the outer ring 141 is referred to as the pressed position, and the orthogonal direction (D2) orthogonal to each of the swing direction (D1) and the axial direction (D3) of the worm shaft 2 is defined. Is simply referred to as the orthogonal direction.

In the vicinity of the pressed position, the outer ring 141 is compressed and deformed from the original shape shown by the chain line in FIG. 5 in the axial direction (D3) of the worm shaft 2 as shown by the solid line in FIG. 5 (in FIG. 5, the outer ring 141 is deformed. The amount of deformation is exaggerated and large). When the outer ring 141 is deformed in this way, the internal gap 144 in the axial direction (D3) of the worm shaft 2 becomes smaller than the original shape, and the outer ring 141 and the ball 143 come into contact with each other in the axial direction (D3) of the worm shaft 2. As a result, when a force in the axial direction (D3) acts on the worm shaft 2, it is possible to prevent the inner ring 142 from moving in the axial direction (D3) together with the worm shaft 2. Therefore, it is possible to prevent the generation of a collision sound caused by the ball 143 colliding with the outer ring 141 or the inner ring 142. The shape of the pressing protrusion 31a is not particularly limited, but it is preferable that the cross section is semicircular or triangular, for example, so as to promote the deformation of the outer ring 141.

On the other hand, in the vicinity of the pressed position, the outer ring 141 and the ball 143 come into contact with each other even in the radial direction of the outer ring 141. As a result, the inner ring 142 is prevented from tilting in the radial direction with respect to the outer ring 141 in the vicinity of the pressed position. Therefore, when the outer ring 141 is pressed in or near the swing direction (D1) by the pressing projection 31a of the washer 31, the inner ring 142 is less likely to tilt toward the swing direction (D1), and the worm shaft 2 moves toward the worm wheel 1. It hinders the swing of.

However, in the present embodiment, the pressing protrusion 31a of the washer 31 is not at a position along the swing direction (D1) in the outer ring 141, but at a position in the orthogonal direction (D2) away from the swing direction (D1). Press. Therefore, as shown in FIG. 3A, the length X of the internal gap 144 in the swing direction (D1) is secured on the swing direction (D1) of the first bearing 4. Therefore, as shown in FIG. 3B, the inner ring 142 of the first bearing 4 tends to tilt toward the swing direction (D1) with respect to the outer ring 141, which prevents the worm shaft 2 from swinging to the worm wheel 1. There is no. In this way, a part of the outer ring 141 of the first bearing 4 is pressed by the pressing protrusion 31a of the washer 31, and the internal gap 144 is partially reduced in the circumferential direction of the first bearing 4, so that the worm shaft 2 swings. When a force in the axial direction (D3) acts on the worm shaft 2 while allowing movement, it is possible to prevent the inner ring 142 from moving in the axial direction (D3) together with the worm shaft 2. As a result, the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142 can be reduced, and the noise of the speed reducer 100 can be reduced.

Further, since the pressing protrusion 31a and the locknut 32 of the washer 31 press the outer ring 141 at positions separated by 180 degrees in the orthogonal direction (D2), the direction in which the inner ring 142 is more likely to tilt as compared with the case where only one point is pressed. Can be controlled. Therefore, it is possible to prevent the worm shaft 2 from swinging in an unintended direction other than the swinging direction (D1).

The pressing projection 31a of the washer 31 is not limited to the form of pressing the outer ring 141 in the orthogonal direction (D2) so as not to prevent the worm shaft 2 having the first bearing 4 as a fulcrum from swinging to the worm wheel 1. The outer ring 141 may be pressed. That is, if the outer ring 141 can be pressed so as to secure the required amount of inclination for reducing the backlash of the worm shaft 2 with the first bearing 4 as a fulcrum to the worm wheel 1, it may deviate from the orthogonal direction (D2).

Further, the washer 31 does not have to have the positioning protrusion 31b formed. In that case, the washer 31 may be accommodated in the accommodating hole 130 of the gear case 3 so that the pressing projection 31a is at a desired position.

Further, the pressing protrusion 31a and the locknut 32 of the washer 31 preferably press the outer ring 141 at positions separated by 180 degrees, but the present invention is not limited to this, and only one location may be pressed, and three or more locations may be pressed. You may press it. Further, it is desirable that the washer 31 has a higher hardness than the outer ring 141. As a result, buckling of the pressing protrusion 31a is prevented when the outer ring 141 is pressed, and the outer ring 141 can be stably deformed.

According to the above embodiment, the following actions are exhibited.

A part of the outer ring 141 of the first bearing 4 that supports the base end side of the worm shaft 2 is pressed by the seat metal 31 and the lock nut 32 in the axial direction (D3) of the worm shaft 2, so that the worm shaft 2 becomes a worm wheel. The internal gap 144 of the first bearing 4 in the axial direction (D3) of the worm shaft 2 can be reduced while ensuring the internal gap 144 of the first bearing 4 in the swing direction (D1) toward 1. As a result, when the worm shaft 2 allows the worm shaft 2 to swing toward the worm wheel 1 and an axial (D3) force acts on the worm shaft 2, the inner ring 142 of the first bearing 4 moves in the axial direction (with the worm shaft 2). It is possible to suppress the movement to D3). Therefore, it is possible to reduce the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142.

Further, the pressing protrusion 31a and the lock nut 32 of the seat metal 31 press the outer ring 141 so as not to prevent the worm shaft 2 having the first bearing 4 as a fulcrum from swinging to the worm wheel 1, so that the worm shaft 2 can be moved. When an axial force (D3) is applied to the worm shaft 2 without hindering the reduction of backlash due to the worm wheel 1, the inner ring 142 of the first bearing 4 moves in the axial direction (D3) together with the worm shaft 2. It can be suppressed from moving. Therefore, it is possible to reduce the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142.

Further, since the pressing protrusion 31a and the locknut 32 of the washer 31 press the outer ring 141 at positions separated by 180 degrees in the orthogonal direction (D2), the direction in which the inner ring 142 is more likely to tilt as compared with the case where only one point is pressed. Can be controlled, and the worm shaft 2 can be prevented from swinging in an unintended direction other than the swinging direction (D1).

The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the above-described embodiments, or to combine the configurations described in the following different modifications. Is.

<Modification example 1>
The first bearing 4 may be sandwiched between the washers 31 from both sides in the axial direction (D3) of the worm shaft 2 and accommodated in the accommodating hole 130 of the gear case 3. That is, the washers 31 may be arranged on both sides of the first bearing 4, and the outer ring 141 of the first bearing 4 may be pressed from both sides in the axial direction (D3) of the worm shaft 2. In this modification, the outer ring 141 is pressed from both sides in the axial direction of the first bearing 4 to be deformed, so that the amount of deformation of the outer ring 141 is uniform on both sides in the axial direction, and rotation failure of the first bearing 4 is prevented. ..

<Modification 2>
As the pressing means, as shown in FIG. 6, a protrusion 141b may be formed on the end surface of the outer ring 141 of the first bearing 4. In the first bearing 4, the protrusion 141b is accommodated in the accommodating hole 130 of the gear case 3 so as to face the gear case 3. When the first bearing 4 receives an axial force from the locknut 32, the protrusion 141b presses the outer ring 141 in the axial direction (D3) of the worm shaft 2. In this modification, since the protrusion 141b is formed on the outer ring 141, the washer 31 becomes unnecessary, and the number of parts of the speed reducer 100 can be reduced. Further, a positioning protrusion for determining the position of the first bearing 4 in the circumferential direction with respect to the gear case 3 may be formed on the outer peripheral surface of the outer ring 141.

<Modification example 3>
In the above embodiment, an example in which a worm gear having a worm 2a as a driving gear and a worm wheel 1 as a driven gear is used as the speed reducer 100 has been described, but the present invention is not limited thereto. A hypoid gear having a hypoid pinion as a driving gear and a hypoid wheel as a driven gear may be used as a speed reducer. Further, the bevel gear may be used as a speed reducer.

<Modification example 4>
In the above embodiment, an example of applying the present invention to the speed reducer 100 of the power steering device 10 has been described, but the present invention can be applied to the speed reducers of various machines such as conveyors, winches, machine tools, and construction machines. it can.

The configuration, operation, and effect of the embodiment of the present invention configured as described above will be collectively described.

The shaft support structure 101 of the speed reducer 100 is a shaft support structure of the speed reducer including a worm shaft 2 connected to the electric motor 7 and a worm wheel 1 that meshes with the worm shaft 2, and is a base end of the worm shaft 2. The worm shaft 2 is attached toward the worm wheel 1 via the first bearing 4 that rotatably supports the side, the second bearing 11 that rotatably supports the tip end side of the worm shaft 2, and the second bearing 11. The first bearing 4 is provided between the inner ring 142 having the inner raceway groove 142a, the outer ring 141 having the outer raceway groove 141a, and the inner raceway groove 142a and the outer raceway groove 141a. The shaft support structure 101 further includes a pressing means for pressing a part of the outer ring 141 in the axial direction of the worm shaft 2.

In this configuration, a part of the outer ring 141 of the first bearing 4 that supports the base end side of the worm shaft 2 is pressed by the pressing means in the axial direction (D3) of the worm shaft 2, so that the worm shaft 2 becomes a worm wheel. The internal gap 144 of the first bearing 4 in the axial direction (D3) of the worm shaft 2 can be reduced while ensuring the internal gap 144 of the first bearing 4 in the swing direction (D1) toward 1. As a result, when the worm shaft 2 allows the worm shaft 2 to swing toward the worm wheel 1 and an axial (D3) force acts on the worm shaft 2, the inner ring 142 of the first bearing 4 moves in the axial direction (with the worm shaft 2). It is possible to suppress the movement to D3).

In the shaft support structure 101 of the speed reducer 100, the pressing means presses the outer ring 141 at positions separated by 180 degrees.

In this configuration, it is possible to control the direction in which the inner ring 142 is likely to tilt as compared with the case where only one point is pressed, and it is possible to prevent the worm shaft 2 from swinging in an unintended direction other than the swinging direction (D1). ..

In the shaft support structure 101 of the speed reducer 100, the pressing means presses the outer ring 141 from both sides in the axial direction (D3) of the worm shaft 2.

In this configuration, since the outer ring 141 is pressed from both sides in the axial direction of the first bearing 4, the amount of deformation of the outer ring 141 becomes uniform on both sides in the axial direction, and rotation failure of the first bearing 4 is prevented.

In the shaft support structure 101 of the speed reducer 100, the pressing means has a washer 31 formed with a pressing protrusion 31a that is pressed against the outer ring 141 in the axial direction of the worm shaft 2.

In this configuration, the pressing protrusion 31a of the washer 31 can press the desired position of the outer ring 141.

The shaft support structure 101 of the speed reducer 100 has a protrusion 141b formed on the outer ring 141 and receiving an external force in the axial direction of the worm shaft 2.

In this configuration, since the protrusion 141b as the pressing means is formed on the outer ring 141, the number of parts can be reduced.

The power steering device 10 includes a reduction gear 100 having a shaft support structure 101 of the speed reducer 100, a worm shaft 2 supported by the shaft support structure 101, and a worm wheel 1 that meshes with the worm shaft 2, and an electric drive source. A motor 7 and a worm wheel 1 are provided on an output shaft 22 that transmits the rotational force of the electric motor 7 to a rack shaft 8 that steers the wheels 6, and a speed reducer 100 reduces the rotation of the worm shaft 2. Then, it is transmitted to the worm wheel 1.

In this configuration, it is possible to provide the power steering device 10 including the speed reducer 100 having low noise.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

It should be noted that the terms vertical, parallel, and orthogonal as described herein do not necessarily mean strict vertical, parallel, and orthogonal, but also include states that are slightly deviated from strict vertical, parallel, and orthogonal.

1 ... worm wheel (driven gear), 2 ... worm shaft (drive gear shaft), 2a ... worm (drive gear), 4 ... 1st bearing, 6 ... wheel, 7 ...・ Electric motor (drive source), 8 ... rack shaft, 10 ... steering device, 11 ... second bearing, 12 ... coil spring (biased member), 22 ... output shaft, 31 ... Seat metal (pressing means, annular member), 31a ... Pressing protrusion (pressing means), 32 ... Lock nut (pressing means), 100 ... Reducer, 101 ... Shaft support structure, 141 ... outer ring, 141a ... outer raceway groove, 141b ... protrusion (pressing means), 142 ... inner ring, 142a ... inner raceway groove, 143 ... ball (rolling element), D1 ...・ Swing direction, D2 ・ ・ ・ orthogonal direction, D3 ・ ・ ・ axial direction of worm axis

Claims (6)

A shaft support structure of a speed reducer including a drive gear shaft connected to a drive source and a driven gear that meshes with the drive gear shaft.
A first bearing that rotatably supports the base end side of the drive gear shaft,
A second bearing that rotatably supports the tip side of the drive gear shaft,
An urging member for urging the driving gear shaft toward the driven gear via the second bearing is provided.
The first bearing is
An inner ring with an inner track groove and
An outer ring with an outer track groove and
It has a plurality of rolling elements arranged between the inner track groove and the outer track groove, and has a plurality of rolling elements.
The shaft support structure is a shaft support structure for a speed reducer, further comprising a pressing means for pressing a part of the outer ring in the axial direction of the drive gear shaft. The shaft support structure of the speed reducer according to claim 1.
The pressing means is a shaft support structure of a speed reducer, characterized in that the outer ring is pressed at positions separated by 180 degrees. The shaft support structure of the speed reducer according to claim 1 or 2.
The pressing means is a shaft support structure of a speed reducer, characterized in that the outer ring is pressed from both sides in the axial direction of the drive gear shaft. The shaft support structure of the speed reducer according to any one of claims 1 to 3.
The shaft support structure of the speed reducer, wherein the pressing means has an annular member formed with protrusions that are pressed against the outer ring in the axial direction of the drive gear shaft. The shaft support structure of the speed reducer according to any one of claims 1 to 3.
The shaft support structure of the speed reducer, wherein the pressing means has a protrusion formed on the outer ring and receives an external force in the axial direction of the drive gear shaft. The reduction gear having the shaft support structure of the speed reducer according to any one of claims 1 to 5, the drive gear shaft supported by the shaft support structure, and the driven gear that meshes with the drive gear shaft. Machine and
The electric motor as the drive source is provided.
The driven gear is provided on an output shaft that transmits the rotational force of the electric motor to a rack shaft that steers the wheels.
The speed reducer is a steering device characterized in that the rotation of the drive gear shaft is reduced and transmitted to the driven gear.

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