JP5985285B2 - Power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus that is applied to, for example, an automobile and includes a speed reduction mechanism configured by a worm gear.

  As a power steering device applied to a conventional automobile, for example, the one described in Patent Document 1 below is known.

  That is, in this power steering device, a preload applying means for applying a preload in the direction in which the worm shaft is engaged with the worm wheel is provided at the tip of the worm shaft.

  This preload applying means is configured by interposing a leaf spring between the outer peripheral surface of the bearing that rotatably supports the tip of the worm shaft on the side opposite to the worm wheel and the peripheral wall surface of the housing facing the bearing. The worm shaft is urged toward the worm wheel which is the meshing direction with the urging force of the leaf spring.

  And about the said leaf | plate spring, the outer periphery of the said leaf | plate spring when a worm shaft receives big input from the worm wheel side, such as the unevenness | corrugation of a road surface, etc. by coat | covering the opposing surface with the surrounding wall surface of a housing with an elastic material. A collision between the surface and the peripheral wall surface of the housing is buffered, and noise generation due to the collision is suppressed.

JP 2007-270943 A

  However, the conventional power steering device only suppresses the generation of noise due to the metal leaf spring body directly colliding with the metal housing by attaching an elastic material to the outer peripheral surface of the leaf spring, For example, after there is a large input from the worm wheel side as described above, the collision of both occurs when the worm shaft returns to the worm wheel side due to the reaction force of the leaf spring caused by the contraction of the leaf spring based on this input. No contribution can be made to this buffer. For this reason, there has been a technical problem that the generation of noise due to a large input from the worm wheel side cannot be sufficiently suppressed.

  The present invention has been devised in view of such technical problems, and the noise caused by the collision of the tooth portions of the worm gear caused by the swing of the bearing (outer race) accompanying the swing of the worm shaft ( Hereinafter, a power steering device capable of suppressing the “gap sound” is provided.

  The present invention relates to a power steering device for assisting a steering force by a rotational force of an electric motor transmitted through a worm gear constituted by a worm shaft and a worm wheel, and in particular, in a gear housing that houses the worm shaft. The bearing for supporting one end of the worm shaft is arranged to be swingable, and an elastic member made of resin or rubber material is interposed between the outer race and the gear housing in the axial direction. Yes.

  According to the present invention, the elastic member attenuates the same swinging of the bearing (outer race) caused by the rapid and large swinging of the worm shaft caused by, for example, excessive input from the road surface side. Generation of rattling noise between the worm wheel and the worm wheel can be suppressed.

1 is a schematic view of a power steering apparatus according to the present invention. FIG. 2 is a diagram illustrating a first embodiment of the present invention, and is a main diagram illustrating a configuration of a reduction gear illustrated in FIG. 1. 2A and 2B are main views according to the first embodiment of the present invention, in which FIG. 2A is an enlarged cross-sectional view of a main part of FIG. 2, FIG. 2B is a cross-sectional view taken along line AA of FIG. FIG. The other example of 1st Embodiment of this invention is shown, (a) is principal part expanded sectional drawing, (b) is CC sectional view taken on the line of (a), (c) is DD line of (a). It is sectional drawing. The 1st modification of 1st Embodiment of this invention is shown, (a) is principal part expanded sectional drawing, (b) is the EE sectional view taken on the line of (a), (c) is F- of (a). It is F line sectional drawing. The 2nd modification of 1st Embodiment of this invention is shown, (a) is principal part expanded sectional drawing, (b) is the GG sectional view taken on the line of (a), (c) is H- of (a). FIG. The 2nd Embodiment of this invention is shown, (a) is a principal part expanded sectional view, (b) is the II sectional view taken on the line of (a), (c) is the JJ sectional view taken on the line (a). is there. The 3rd Embodiment of this invention is shown, (a) is principal part expanded sectional drawing, (b) is KK sectional view taken on the line of (a), (c) is LL sectional view taken on the line of (a). is there. The 4th Embodiment of this invention is shown, (a) is a principal part expanded sectional view, (b) is the MM sectional view taken on the line of (a), (c) is the NN sectional view taken on the line (a). is there. The other example of this invention is shown, (a) is a principal part expanded sectional view, (b) is the OO line sectional view of (a), (c) is the PP sectional view taken on the line (a).

  Hereinafter, embodiments of a power steering apparatus according to the present invention will be described in detail with reference to the drawings. In the following embodiment, the power steering device is applied to a steering device for an automobile as in the conventional case.

  1 to 3 show a first embodiment of a power steering device of the present invention. As shown in FIG. 1, this power steering device has an input shaft whose one axial end is linked to a steering wheel SW so as to be integrally rotatable. 1 (corresponding to the steering shaft of the present invention) and an output shaft 2 whose one end side in the axial direction is linked to the steered wheels WR and WL via a well-known rack and pinion mechanism 3 via a torsion bar (not shown) These two shafts 1 and 2 and the rack and pinion mechanism 3 constitute the steering mechanism of the present invention. The rack and pinion mechanism 3 includes a pinion tooth 2a created at one end of the output shaft 2 and a rack shaft 4 having rack teeth 4a meshing with the pinion tooth 2a in a predetermined axial range. Both ends of the shaft 4 are linked to the steered wheels WR and WL via tie rods 5 and 5.

  With such a configuration, when the steering wheel SW is rotated, the input shaft 1 is rotated in synchronization with the rotation of the input shaft 1, whereby the torsion bar (not shown) is twisted and follows the input shaft 1 by the elastic force of the torsion bar. As a result, the output shaft 2 rotates. As a result, the rotational movement of the output shaft 2 is converted into the linear (axial) movement of the rack shaft 4, and the knuckles 6 and 6 are moved to the left and right via the tie rods 5 and 5 along with the axial movement of the rack shaft 4. As a result, the steered wheels WR and WL are steered.

  Further, the power steering device is based on a torque sensor 7 that detects a steering torque by the driver based on the relative rotational displacement amount of the input shaft 1 and the output shaft 2, and based on a detection result of the torque sensor 7, a vehicle speed signal, and the like. An electric motor 8 that is driven and controlled by a vehicle-mounted electronic control unit 9 and generates a steering assist torque according to the steering torque. The speed reducer 10 transmits the rotational force of the electric motor 8 to the output shaft 2. And. As a result, when the driver performs steering, the rotational drive direction of the electric motor 8 is switched according to the steering direction, and the steering assist torque according to the steering torque by the driver is output with the output of the speed reducer 10 as the output shaft. 2 is given.

  As shown in FIG. 2, the speed reducer 10 is configured by a worm gear housed in a gear housing 20 that is shared with a housing that houses the output shaft 2, and the worm gear is a drive shaft of the electric motor 8. The worm shaft 11 is coaxially connected to the tip so as to extend the shaft, and both end portions in the axial direction are rotatably supported by the first bearing 13 and the second bearing 14, and can rotate integrally with the outer periphery of the output shaft 2. And a worm wheel 12 that meshes with a tooth portion 11a of the worm shaft 11 in a torsional relationship via a tooth portion 12a formed on the outer periphery thereof. Note that the housing for housing the output shaft 2 and the gear housing 20 do not necessarily have to be configured integrally, and may be configured separately.

  The worm shaft 11 is housed in a shaft housing portion 21 formed on the axis of the drive shaft of the electric motor 8 inside the gear housing 20, and the worm wheel 12 is placed inside the gear housing 20. It is accommodated in a wheel accommodating portion 22 formed so as to be orthogonal to the shaft accommodating portion 21 and so that a predetermined range faces the shaft accommodating portion 21.

  The shaft housing portion 21 is formed in a stepped diameter-reduced shape toward one end side which is the bottom side on the right side in FIG. 2, and the first bearing 13 is provided in the small diameter portion 23 formed at the one end portion. A preload application mechanism 15 is provided between the first bearing 13 and the small-diameter portion 23 so as to apply a preload to the worm shaft 11 in a direction to mesh with the worm wheel 12. . That is, the preload applying mechanism 15 more strongly biases the worm shaft 11 toward the worm wheel 12 while elastically holding the first bearing 13 in the radial direction of the worm wheel 12, thereby The backlash associated with the engagement with the wheel 12 is adjusted and optimized.

  In addition, an intermediate diameter portion 24 that accommodates the tooth portion 11a of the worm shaft 11 is formed in the axial intermediate portion of the shaft accommodating portion 21, and the wheel in the axial intermediate portion of the intermediate diameter portion 24 A communication portion 27 that communicates with the housing portion 22 is formed, and the tooth portion 11 a of the worm shaft 11 and the tooth portion 12 a of the worm wheel 12 mesh with each other via the communication portion 27.

  Further, at the other end portion of the shaft accommodating portion 21, a large diameter portion 25 (corresponding to a bearing accommodating portion according to the present invention) formed by expanding the diameter of the intermediate diameter portion 24 via a step portion 26 is provided. It is configured. The second bearing 14 is inserted into the large-diameter portion 25 so as to abut against the stepped portion 26, and the bearing holding member 16 is screwed from the outside thereof, whereby the bearing holding member 16 is inserted. The second bearing 14 is held in a sandwiched state by the step portion 26 and the step portion 26.

  Here, the first bearing 13 is configured by a well-known ball bearing, while the second bearing 14 is configured as a so-called swinging bearing that pivotally supports the worm shaft 11. In particular, as shown in FIG. 3 (a), an inner race 31 fitted to the outer peripheral surface of the one end portion 11b of the worm shaft 11, and the outer race is disposed on the outer peripheral side of the inner race 31, and a longitudinal section on the outer peripheral surface thereof. An outer race 32 having a sliding surface 32a formed in a convex arc shape, and a shape corresponding to the sliding surface 32a disposed on the outer peripheral side of the outer race 32 and formed on the inner peripheral surface thereof A swing support member 33 that swingably supports the outer race 32 by an arc-shaped support surface 33a, a plurality of balls 34 interposed between the outer race 32 and the inner race 31; It is configured, and is fitted and fixed to the inner peripheral surface of the large-diameter portion 25 by being pressed into the large-diameter portion 25 through the swing support member 33.

  Further, as shown in FIGS. 3A to 3C, the step portion 26 and the bearing holding member 16 are damped in the swing of the outer race 32 so as to face the outer race 32 of the second bearing 14. The 1st elastic member 17 and the 2nd elastic member 18 which are a pair of elastic members with which it supplies to are arrange | positioned. Each of the first and second elastic members 17 and 18 is formed by forming a rubber material in an annular shape, and is constituted by a known O-ring.

  That is, in the step portion 26, a slight step is provided between the outer peripheral region and the inner peripheral region, and the swing support member cooperates with the bearing holding member 16 by the outer step portion 26a serving as the outer peripheral region. The first elastic member 17 is accommodated and held in the concave first annular groove 41 formed along the circumferential direction in the inner stepped portion 26b serving as the inner peripheral region. Yes.

  The inner step 26b is formed to extend radially outward from the outer peripheral edge of the outer race 32 so that the outer race 32 does not interfere with the outer step 26a when the outer race 32 swings. It is configured.

  The first annular groove 41 has an axial clearance C1 formed between the first annular groove 41 and the inner end surface 32b of the outer race 32 in a normal use state where excessive force is not input from the worm wheel 12 side, and Even when the first elastic member 17 undergoes the largest elastic deformation (collapse deformation), such as when there is excessive input from the worm wheel 12 side, the first elastic member 17 is not completely buried, and the outer race The groove depth is set such that 32 does not contact the inner stepped portion 26b.

  Further, the first annular groove 41 is provided in the inner step portion 26b so that the center position X of the groove width is biased radially inward. As a result, when the outer race 32 swings, The outer peripheral edge of the outer race 32 is not in contact with the elastic member 17.

  On the other hand, the bearing holding member 16 is also configured such that the inner surface facing the outer race 32 is a stepped portion 28 similar to the stepped portion 26, and slightly protrudes in the radial region outside the outer peripheral edge of the outer race 32. The swinging support member 33 is held between the outer stepped portion 28a of the stepped portion 28 in the sandwiched state by the outer stepped portion 28a and is formed in a concave shape in the radial region on the inner peripheral side thereof. In the step portion 28b, the second elastic member 18 is accommodated and held in a concave second annular groove 42 formed along the circumferential direction.

  The second annular groove 42, like the first annular groove 41, has an axial clearance C2 formed between the inner end surface 32b of the outer race 32 and the worm in the normal use state. Even when the second elastic member 18 is most elastically deformed (collapsed) based on an excessive input from the wheel 12 side, the groove depth is set so that the second elastic member 18 is not completely buried. In addition, the center X of the groove width is provided so as to be biased radially inward.

  Hereinafter, the characteristic operation of the power steering apparatus according to the present embodiment will be described with reference to FIGS. 2 and 3.

  First, in a normal use state in which excessive input does not act from the worm wheel 12 side, when the worm shaft 11 is rotated by the output of the electric motor 8, the worm shaft 11 is warmed based on the urging force of the preload applying mechanism 15. The first and second bearings 13 and 14 are rotatably supported by the wheel 12 in a properly meshed state. For this reason, in the second bearing 14, the inner race 31 rotates relative to the outer race 32 while the outer race 32 maintains a separated state from both the first and second elastic members 17 and 18. The worm shaft 11 is rotationally supported.

  On the other hand, when an excessive force is input from the road surface side by, for example, a deep ridge, the input acts to push the worm shaft 11 far away from the worm wheel 12 side. As a result, the worm shaft 11 is a bearing by the second bearing 14. With the center Z as a fulcrum, the other end side swings relatively large in the direction away from the worm wheel 12. As a result, the outer race 32 of the second bearing 14 abuts (elastically contacts) the first and second elastic members 17 and 18 with the large swing of the worm shaft 11, thereby generating the elastic members 17 and 18. As a result, the worm shaft 11 acts in the form of attenuating excessive input from the road surface side received by the worm shaft 11 from the worm wheel 12 side. Will be attenuated).

  That is, since the sudden swing of the worm shaft 11 is attenuated, the worm shaft 11 and the worm wheel 12 are caused by a large reaction force of the preload applying mechanism 15 generated along with the rapid swing of the worm shaft 11. The inconvenience of a large collision, specifically, the generation of rattling noise due to the collision of both teeth 11a and 12a is suppressed. Furthermore, since the excessive swing of the worm shaft 11 is suppressed, the excessive input acts on the swing support member 33 due to the excessive swing of the worm shaft 11, specifically, Therefore, the occurrence of damage to the second bearing 14 and a decrease in durability are avoided.

  As described above, in the power steering apparatus according to the present embodiment, excessive input is generated from the road surface side, for example, by elastically supporting the swing of the outer race 32 by the first and second elastic members 17 and 18. It is possible to attenuate the swing of the second bearing 14 caused by the worm shaft 11 swinging rapidly and greatly. Thereby, generation | occurrence | production of the rattling sound between both teeth 11a and 12a of the worm shaft 11 and the worm wheel 12 can be suppressed.

  In addition, in the present embodiment, since each of the elastic members 17 and 18 is configured in a ring shape, the damping action is obtained in almost the entire circumference of the outer race 32. As a result, the outer race 32 is swung rapidly and greatly. It is possible to attenuate more effectively and to sufficiently suppress the rattling noise between the worm gears.

  Further, the elastic members 17 and 18 are also biased toward the inner peripheral side of the inner step portions 26b and 28b formed by dividing the step portions 26 and 28 into two radial regions. For example, the first and second elastic members 17 and 18 are arranged on the outer peripheral side of the inner step portions 26b and 28b as shown in FIG. It is also possible to avoid the inconvenience that the outer peripheral edges of the outer race 32 come into contact with the second elastic members 17 and 18. As a result, damage to the first and second elastic members 17 and 18 that may occur due to contact of the outer peripheral edge of the outer race 32, a decrease in durability, and the like are also avoided.

  In addition, the holding portions of the elastic members 17 and 18 have a substantially U-shaped vertical end surface having a single opening such as the annular grooves 41 and 42, and the elastic members 17 and 18 are deformed. By limiting to only one direction, the management of the elastic characteristics of the elastic members 17 and 18 is facilitated, and the desired damping action is ensured.

  In the case of the present embodiment, the axial gap C1 is interposed between the first and second elastic members 17 and 18 and the outer race 32 in a normal use state without excessive input. Therefore, the first and second elastic members 17 and 18 do not hinder the swing of the worm shaft 11 in the normal use state. That is, as a result of obtaining a smooth swinging action of the second bearing 14, good meshing between the worm shaft 11 and the worm wheel 12 based on an appropriate preload by the preload applying mechanism 15 is also ensured.

  In the present embodiment, the configuration in which the elastic members 17 and 18 are arranged in the step portion 26 of the gear housing 20 and the step portion 28 of the bearing holding member 16 is exemplified. However, the oscillation of the outer race 32 is damped. In obtaining the effect of the present invention, if an elastic member is provided on one side of the gear housing 20 or the bearing holding member 16, the swing of the outer race 32 is attenuated by the elastic member provided on the one side. Therefore, the elastic member is not necessarily provided on both the gear housing 20 and the bearing holding member 16.

  FIG. 5 shows a first modification of the first embodiment of the present invention, in which the axial gaps C1 and C2 interposed between the outer race 32 and the first embodiment are eliminated. The first and second elastic members 17 and 18 and the outer race 32 are configured to always contact each other.

  Therefore, in the case of this modification, when the outer race 32 swings due to the swing of the worm shaft 11, the outer race 32 is swung by the first and second elastic members 17 and 18 from the beginning of the swing. Can be attenuated. Thereby, the sudden and large swinging of the outer race 32 due to the excessive input or the like is more effectively attenuated, and the rattling noise between the worm gears can be satisfactorily suppressed.

  FIG. 6 shows a second modification of the first embodiment of the present invention, in which the configuration of the first and second annular grooves 41 and 42 in the first embodiment is changed.

  That is, in this modification, in the first and second annular grooves 41 and 42, the groove depth is large on the worm wheel 12 side (D1 in FIG. 6A) and small on the anti-worm wheel 12 side ( D2) in FIG. 6A is configured to change in the circumferential direction, and the flatness ratio (filling rate) of the first and second elastic members 17 and 18 is changed in the circumferential direction. Yes.

  With this configuration, in this modification, it is possible to further optimize the damping characteristics of the first and second elastic members 17 and 18 with respect to the swing of the outer race 32, and the generation of the rattling noise is more effective. Served for suppression.

  FIG. 7 shows a second embodiment of the present invention, in which the configurations of the first and second elastic members 17 and 18 are changed with respect to the first embodiment.

  That is, in the present embodiment, the first and second annular grooves 41 and 42 according to the first embodiment are eliminated, and instead, the worm wheel 12 in the circumferential direction of the inner step portions 26b and 28b is provided. A pair of first and second holding holes 43 and 44 having a substantially rectangular cross section are formed at the nearest and farthest positions, and each of the holding holes 43 and 44 holds each of the holding holes 43 and 44. Each pair of first and second elastic members 17 and 18 formed in a substantially block shape having a cross-sectional shape corresponding to the holes 43 and 44 is accommodated and held.

  In the present embodiment, the basic configuration such as the depth dimension of the first and second holding holes 43 and 44 and the radial position of each inner stepped portion 26b and 28b is also described in the first embodiment. It is the same.

  From the configuration as described above, the present embodiment can provide the same effects as those of the first embodiment. In particular, in the present embodiment, the elastic members 17 and 18 Since the respective elastic members 17 and 18 are formed in a ring shape (see FIG. 6), the circumferential positions of the gear housing 20 and the bearing holding member 16 are compared with each other. Elastic properties can be easily changed.

FIG. 8 shows a reference example of the present invention, in which the configuration of the first and second holding holes 43 and 44 is changed with respect to the second embodiment.

That is, in this reference example , the inner peripheral walls of the first and second holding holes 43 and 44 are deleted, and the first and second holding holes 43 and 44 are axially outer (outer race 32 side) and radially inner. The first and second cutout portions 45 and 46 are open to both sides (on the worm shaft 11 side), and the first and second elastic members 17 and 18 are formed by the first and second cutout portions 45 and 46. Is to be stored and held.

Also in this reference example , the basic configuration such as the depth dimension of the first and second cutout portions 45 and 46 and the radial position of the inner stepped portions 26b and 28b is described in the second embodiment. It is the same.

Therefore, with this configuration, in the case of the present reference example , the holding portions of the first and second elastic members 17 and 18 are formed in a notch shape that opens radially inward of the gear housing 20 and the bearing holding member 16. Due to the formation, at least the first and second cutout portions 45 and 46 can be processed more easily than in the case of the second embodiment. As a result, the productivity of the apparatus is improved, and the manufacturing cost is thereby reduced.

FIG. 9 shows a third embodiment of the present invention, in which the holding forms of the first and second elastic members 17 and 18 are changed with respect to the reference example .

  In other words, in the present embodiment, the first and second elastic members 17 and 18 are made of elastic materials (first and second elastic members 51 and 52) formed of the same rubber material, respectively. It is configured integrally by being housed and held in a metal holder (first and second holders 53 and 54), and is housed and held by the first and second cutout portions 45 and 46. Yes.

  The height dimensions of the first and second holders 53 and 54 are set to be substantially the same as the depth dimensions of the first and second notches 45 and 46, and the holders 53 and 54 are connected to the outer race 32. The inconvenience of hindering the swinging of the motor is avoided. And about basic composition, such as the protrusion amount of each said elastic material 51,52 from each said notch 45,46, and the radial direction position with respect to each said inner side step part 26b, 28b of this each elastic material 51,52 Is the same as in the third embodiment.

  Thus, in the present embodiment, the elastic material (the first and second elastic materials 51 and 52) is transferred to the first and second cutout portions 45, via the holder (the first and second holders 53 and 54). Since it is configured to be held by 46, it is possible to configure the holding portions of the elastic members 51 and 52 in a cutout shape while restricting the deformation of the elastic members 51 and 52. Thereby, it is possible to achieve both good workability of the notches 45 and 46 and good damping action by the elastic members 51 and 52.

  The present invention is not limited to the configuration of each of the above embodiments. For example, the shape, size, and quantity of each of the elastic members 17 and 18 can be arbitrarily determined by tuning the damping characteristics with respect to the swing of the outer race 32. It can be changed.

  Further, only in the first embodiment, the axial gaps C1 and C2 are interposed between the first and second elastic members 17 and 18 and the outer race 32. The same applies to the fourth embodiment.

Further, in the second to third embodiments, a pair of the first and second elastic members 17 and 18 are provided, but it is not always necessary to form a pair. For example, as shown in FIG. The gear housing 20 and the bearing holding member 16 may have a single arrangement. Even in the arrangement, it is not necessary to be provided on both the gear housing 20 or the bearing holding member 16, and if it is provided on either one side, the above-described unique effects of the present invention can be achieved.

  Hereinafter, technical ideas other than those described in the scope of claims understood from the embodiment and the like will be described.

(A) In the power steering device according to claim 1,
The bearing is held in a sandwiched state between a bearing holding member screwed from the opening end side of the bearing housing portion and the stepped portion,
The power steering apparatus according to claim 1, wherein the elastic member is interposed between the bearing holding member and the outer race.

  By adopting such a configuration, the elastic member on the bearing holding member side and the elastic member on the stepped portion side can cooperate to more effectively attenuate sudden and large swinging of the outer race. As a result, it is possible to sufficiently suppress the rattling noise between the worm gears.

(B) In the power steering device according to claim 1,
The power steering device according to claim 1, wherein the elastic member is configured to abut an end face in the axial direction of the outer race and not to contact an outer peripheral edge of the outer race.

  With such a configuration, it is possible to avoid the inconvenience that the elastic member is damaged when the outer peripheral edge of the outer race contacts.

(C) In the power steering device according to claim 1,
A power steering apparatus, wherein the elastic member is formed in a substantially ring shape.

  With such a configuration, as a result of obtaining the swinging action of almost the entire outer race, the sudden and large swinging of the outer race can be more effectively attenuated, and the rattling noise between the worm gears can be reduced. Provided with sufficient suppression.

(D) In the power steering device according to (c),
On the axial end surface of the bearing holding member facing the outer race, a concave elastic material holding portion for receiving the elastic member is formed,
The power steering device according to claim 1, wherein the elastic material holding portion is configured to have different depths in a region close to the worm wheel and a region far from the worm wheel.

  In this way, by changing the depth of the elastic material holding portion, it becomes possible to adjust the damping characteristics such as the magnitude of the damping action in the circumferential region, and as a result, the outer race suddenly and greatly fluctuates. The movement can be attenuated more effectively.

(E) In the power steering device according to claim 1,
A concave elastic material holding portion for accommodating the elastic member is formed in the axial end surface of the step portion facing the outer race, and
The power steering device according to claim 1, wherein the elastic material holding portion is configured to open only on an outer side in the axial direction facing the outer race.

  By limiting the elastic deformation of the elastic member in this way, the elastic characteristics of the elastic member can be easily managed, and as a result, a desired damping action can be secured by the elastic member.

(F) In the power steering apparatus according to claim 1,
A concave elastic material holding portion for accommodating the elastic member is formed in the axial end surface of the step portion facing the outer race, and
The power steering device, wherein the elastic material holding portion is configured to open to an axially outer side facing the outer race and a radial inner side facing the worm shaft.

  With such a configuration, good workability can be obtained, which is used for improving productivity and reducing manufacturing costs.

(G) In the power steering device according to (f),
The elastic member is held by a holding member having a U-shaped cross section that opens outward in the axial direction, and is fitted and fixed to the elastic material holding portion so as to face the outer race via the holding member. A power steering device characterized by that.

  By comprising in this way, it becomes possible to manage the said elastic characteristic easily, after ensuring the said favorable work workability | operativity. In other words, it is possible to achieve both good workability of the elastic material holding portion and good damping action by the elastic member.

1 ... Input shaft (steering shaft)
3 ... Rack and pinion mechanism (steering mechanism)
8 ... Electric motor 11 ... Worm shaft 12 ... Worm wheel 14 ... Second bearing (bearing)
17 ... 1st elastic member (elastic member)
20 ... Gear housing 21 ... Shaft housing portion 22 ... Wheel housing portion 25 ... Large diameter portion (bearing housing portion)
26 ... Step 31 ... Inner race 32 ... Outer race 33 ... Swing support member 34 ... Ball SW ... Steering wheel WR, WL ... Steering wheel

Claims (2)

A steering mechanism that has a steering shaft connected to the steering wheel and steers the steered wheels according to the rotation of the steering wheel;
A worm wheel provided on the steering shaft;
A worm shaft meshing with the worm wheel;
An electric motor that is provided on one end of the worm shaft and applies a steering assist force to the steering mechanism;
A gear housing having a wheel housing portion for housing the worm wheel and a shaft housing portion for housing the worm shaft;
An inner step portion and an outer step portion that are provided on the electric motor side from the shaft housing portion and are formed in a stepped diameter-enlarged shape so that the inner diameter becomes larger in two steps than the shaft housing portion toward the electric motor side. A bearing housing formed by an outer step located on the electric motor side of the two steps formed by
The inner race that is accommodated and disposed in the bearing accommodating portion and is fitted on the outer periphery of the worm shaft, and the outer race is provided with an axial gap between the inner step portion on the outer peripheral side of the inner race. An outer race having a substantially arc-shaped cross section in which the outer diameter gradually decreases from the axial intermediate portion toward both axial end sides, and a plurality of interlaces interposed between the inner race and the outer race A ball is provided on the outer peripheral side of the outer race so as to abut against the outer step portion , and the inner peripheral surface of the outer race is formed in a substantially circular arc shape in cross section along the arc shape of the outer peripheral surface of the outer race. A movable support member, wherein the end of the worm shaft is rotatable, and the outer race swings so that the end of the worm shaft is used as a fulcrum. A bearing for swingably supporting the Mushafuto,
Wherein interposed between the inner stepped portion and the axial end surface of the outer race, the largest the outer race in the axial direction in the gap even when crushed deformed by bulging with the radial direction of the outer race and the inner stage An elastic member made of a resin or rubber material that can be elastically deformed so as to suppress contact with the part ;
With
A notch is formed in the axial end surface of the inner step portion facing the outer race so that an elastic material holding portion having a concave cross-sectional shape that houses the elastic member opens only on the outer side in the axial direction facing the outer race. A power steering apparatus characterized by being provided. A steering mechanism that has a steering shaft connected to the steering wheel and steers the steered wheels according to the rotation of the steering wheel;
A worm wheel provided on the steering shaft;
A worm shaft meshing with the worm wheel;
An electric motor that is provided on one end of the worm shaft and applies a steering assist force to the steering mechanism;
A gear housing having a wheel housing portion for housing the worm wheel and a shaft housing portion for housing the worm shaft;
An inner step portion and an outer step portion that are provided on the electric motor side from the shaft housing portion and are formed in a stepped diameter-enlarged shape so that the inner diameter becomes larger in two steps than the shaft housing portion toward the electric motor side. A bearing housing formed by an outer step located on the electric motor side of the two steps formed by
The inner race that is accommodated and disposed in the bearing accommodating portion and is fitted on the outer periphery of the worm shaft, and the outer race is provided with an axial gap between the inner step portion on the outer peripheral side of the inner race. An outer race having a substantially arc-shaped cross section in which the outer diameter gradually decreases from the axial intermediate portion toward both axial end sides, and a plurality of interlaces interposed between the inner race and the outer race A swing support member provided with a ball and a shape in contact with the outer step portion on the outer peripheral side of the outer race, the inner peripheral surface of which is formed in a substantially circular arc shape along the arc shape of the outer peripheral surface of the outer race The worm shaft is rotatable about one end side of the worm shaft and the outer race swings so that the one end side of the worm shaft is a fulcrum. A bearing for swingably supported,
Wherein interposed between the inner stepped portion and the axial end surface of the outer race, the largest the outer race in the axial direction in the gap even when crushed deformed by bulging with the radial direction of the outer race and the inner stage An elastic member made of a resin or rubber material that can be elastically deformed so as to suppress contact with the part ;
On the axial end surface of the inner step portion facing the outer race, there is an elastic material holding portion having an L-shaped longitudinal section and a U-shaped transverse section for housing the elastic member in a tangential direction of the opening edge of the shaft housing portion. And the elastic material holding portion is configured to open to an axially outer side facing the outer race and a radial inner side facing the worm shaft, and
The elastic member is open in the axial direction outside, and the held by the horizontal U-shaped section and comprising a holding member extending in the extending direction of the elastic material holding portion, the holding member, the said opening outer race facing power steering apparatus in the longitudinal direction end sides in the form to be characterized in that it is fitted and fixed to the longitudinal end side of the elastic member holding portion.

Images