JP4994272B2 - Rack and pinion steering system - Google Patents

Description

  The present invention provides a steering gear box for transmitting an operation of a steering wheel to a wheel, a pinion connected to the steering wheel, a rack bar meshing with the pinion, a rack bar connected to the wheel, and the rack A housing that slidably supports the bar, a rack guide that slidably fits in a guide hole formed in the housing, and an arc-shaped cross section formed on the back surface of the rack bar that urges the rack guide. The present invention relates to a rack and pinion type steering apparatus comprising a first sliding surface and a resilient member that abuts a second sliding surface having an arcuate cross section formed at a tip of the rack guide.

Such a rack-and-pinion type steering device is known from Patent Document 1 below.
JP 2005-247079 A

  FIG. 10 shows a contact state between the first sliding surface 29 a of the rack bar 29 and the second sliding surface 31 a of the rack guide 31 in the conventional rack and pinion type steering device. The first sliding surface 29a of the rack bar 29 is composed of a single arc surface having a radius R1 centered on O1, and the second sliding surface 31a of the rack guide 31 is the radius R1 centered on O2 and O2. The first sliding surface 29a and the second sliding surface 31a are in line contact with each other at two locations. Therefore, if the portion in line contact with the long-term use is unevenly worn, there is a problem that the play occurs between the rack bar 29 and the rack guide 31 and causes noise.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent noise caused by play between a rack bar and a rack guide in a rack and pinion type steering apparatus.

To achieve the above object, according to the first aspect of the present invention, a steering gear box for transmitting an operation of a steering wheel to a wheel includes a pinion connected to the steering wheel and a rack meshing with the pinion. A rack bar that is connected to the wheel, a housing that slidably supports the rack bar, a rack guide that slidably fits in a guide hole formed in the housing, and the rack guide A resilient member that biases and abuts a second sliding surface having an arcuate cross section formed at a tip of the rack guide on a first sliding surface having an arcuate cross section formed on a back surface of the rack bar; In the rack and pinion type steering device, a notch for reducing the wall thickness is formed on the outer peripheral surface of the second sliding surface of the rack guide on both ends. And, when the second sliding surface is pressed by the resilient member to the first slide surface, the first that both distal end portion of the second sliding surface is brought into contact with the first sliding surface A rack and pinion type steering device is proposed.

  According to the invention described in claim 2, the steering gear box for transmitting the operation of the steering wheel to the wheel has a pinion connected to the steering wheel and a rack meshing with the pinion. A rack bar to be connected; a housing that slidably supports the rack bar; a rack guide that is slidably fitted into a guide hole formed in the housing; and the rack bar that biases the rack guide, A rack-and-pinion steering device comprising: a first sliding surface having an arc-shaped cross section formed on the back surface of the rack guide; and a resilient member for contacting the second sliding surface having an arc-shaped cross section formed at the tip of the rack guide. The both end portions of the second sliding surface are escaped to the inner peripheral surface of the guide hole facing the outer peripheral surface on the both end portions side of the second sliding surface of the rack guide. Rack and pinion steering apparatus characterized by forming a notch in Sutame is proposed.

According to the invention described in claim 3, in addition to the structure of claim 2, when the second sliding surface is pressed against the first sliding surface by the elastic member, A rack and pinion type steering device is proposed in which both end portions of the second sliding surface abut on the first sliding surface.

According to the invention described in claim 4 , in addition to the structure of any one of claims 1 to 3, a first one formed at the tip of the rack guide and in contact with the first sliding surface. The two sliding surfaces have the same radius as the radius of the first sliding surface, and the second sliding surface is bent at an intermediate portion so that both ends approach each other. A rack and pinion type steering device is proposed in which the first and second sliding surfaces come into surface contact by elastic deformation.

According to the fifth aspect of the present invention, in addition to the structure of any one of the first to third aspects, a first portion formed at the tip of the rack guide and in contact with the first sliding surface. The two sliding surfaces have a radius slightly smaller than the radius of the first sliding surface, and the first and second sliding surfaces are in surface contact by elastic deformation of the rack guide. A rack and pinion type steering device is proposed.

According to the invention described in claim 6 , in addition to the configuration of any one of claims 1 to 3, the first formed on the tip of the rack guide and abutting on the first sliding surface. The two sliding surfaces are configured with only a radius slightly smaller than the radius of the first sliding surface, and the first and second sliding surfaces are brought into surface contact by elastic deformation of the rack guide. A rack-and-pinion steering device is proposed.

  The lower housing 21 of the embodiment corresponds to the housing of the present invention, the spring 33 of the embodiment corresponds to the elastic member of the present invention, and the contact c of the embodiment is the second sliding surface of the present invention. Corresponds to the middle part.

According to the configuration of the first aspect, the steering torque that acts on the meshing portion between the rack and the pinion formed on the rack bar acts to separate the rack bar from the pinion, but is slidable in the guide hole of the housing. The meshing state of the rack and the pinion can be appropriately maintained by energizing the rack guide to be fitted with the elastic member and bringing the rack bar into contact with the back surface. At this time, a notch for reducing the wall thickness is formed on the outer peripheral surface of the both ends of the second sliding surface of the rack guide, and the second sliding surface is pressed against the first sliding surface by the resilient member. When the first and second sliding surfaces are first brought into contact with the first sliding surface , the rack guide is easily elastically deformed by the urging force of the resilient member so that the first and second sliding surfaces are in contact with each other . 2 The sliding surfaces can be reliably brought into surface contact, and uneven wear of the sliding surfaces can be suppressed to prevent the generation of noise due to backlash.

  According to the second aspect of the present invention, the steering torque that acts on the meshing portion between the rack and the pinion formed on the rack bar acts to separate the rack bar from the pinion, but is slidable in the guide hole of the housing. The rack guide and the pinion can be appropriately maintained in an engaged state by urging the rack guide fitted to the rack with a resilient member and bringing the rack bar into contact with the back surface. At this time, notches are formed in the inner peripheral surface of the guide hole facing the outer peripheral surface of the both ends of the second sliding surface of the rack guide so as to release both ends of the second sliding surface. The rack guide is easily elastically deformed by the urging force of the generating member to ensure that the first and second sliding surfaces are in surface contact, and the uneven wear of the sliding surfaces is suppressed to prevent the generation of noise due to backlash. Can do.

According to the configuration of claim 3, when the second sliding surface is pressed against the first sliding surface by the elastic member, first, both end portions of the second sliding surface are first brought into the first sliding surface. Since the contact is made, the rack guide can be more easily elastically deformed by the urging force of the resilient member, and the first and second sliding surfaces can be more reliably brought into surface contact.

According to the fourth aspect of the present invention, the second sliding surface formed at the tip of the rack guide and in contact with the first sliding surface of the rack bar has the same radius as the radius of the first sliding surface. Since the second sliding surface is bent at the intermediate portion so that both tip portions approach each other, the rack guide is elastically deformed by the urging force of the resilient member, and the first and second sliding surfaces are surfaces. By contacting, uneven wear of those sliding surfaces can be suppressed and generation of noise due to play can be prevented.

According to the fifth aspect of the present invention, the second sliding surface formed at the tip of the rack guide and in contact with the first sliding surface of the rack bar has a radius slightly smaller than the radius of the first sliding surface. Since the rack guide is elastically deformed by the urging force of the elastic member and the first and second sliding surfaces come into surface contact with each other, the uneven wear of these sliding surfaces is suppressed and noise caused by backlash is generated. Can be prevented.

According to the configuration of claim 6, the rack guide of the second sliding surface which tip is formed in contact with the first sliding surface of the rack bar is only radius slightly smaller than the radius of the first sliding surface since the in formed, the both distal end of the second sliding surface is securely initially in contact with the first sliding surface, the first rack guide by the biasing force of the elastic member is elastically deformed, the second sliding When the moving surfaces come into surface contact, uneven wear of these sliding surfaces can be suppressed, and generation of noise due to play can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 4 show a first embodiment of the present invention. FIG. 1 is an overall perspective view of an electric power steering apparatus, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. FIG. 4 is a diagram showing the shape of the rack bar and the rack guide in a free state.

  As shown in FIG. 1, the upper steering shaft 12 that rotates integrally with the steering wheel 11 has a pinion shaft 17 that protrudes upward from the speed reducer 16 via an upper universal joint 13, a lower steering shaft 14, and a lower universal joint 15. Connected to. Tie rods 19 and 19 projecting from the left and right ends of the steering gear box 18 connected to the lower end of the speed reducer 16 are connected to knuckles (not shown) of the left and right wheels WL and WR. An assist motor M is supported on the speed reducer 16, and the operation of the assist motor M is controlled by an electronic control unit U to which a signal from the steering torque detecting means St stored in the speed reducer 16 is input. .

  As shown in FIG. 2, the speed reducer 16 includes a lower housing 21 integrated with the steering gear box 18, an intermediate housing 23 coupled to the upper surface thereof by bolts 22, and an upper housing coupled to the upper surface thereof by bolts 24. 25, and the pinion shaft 17 is rotatably supported by the lower housing 21 and the upper housing 25 by ball bearings 26 and 27. A pinion 28 provided at the lower end of the pinion shaft 17 meshes with a rack 30 provided on a rack bar 29 that moves left and right inside the steering gear box 18.

  A substantially cylindrical rack guide 31 is slidably accommodated in a guide hole 21 a having a circular cross section formed in a lower housing 21 constituting a part of the steering gear box 18. The first sliding surface 31a of the arcuate cross section on the back surface of the rack bar 29 is formed by a spring 33 disposed between the second sliding surface 31a having an arcuate cross section formed at the tip of the rack guide 31 and the nut member 32 that closes the guide hole 21a. By biasing toward the sliding surface 29 a, the rack 30 can be properly meshed with the pinion 28 while suppressing the bending of the rack bar 29.

  A worm 35 provided on the rotating shaft 34 of the assist motor M extending inside the speed reducer 16 meshes with a worm wheel 36 fixed to the pinion shaft 17. Therefore, when the assist motor M is driven, the pinion shaft 17 of the speed reducer 16 rotates through the worm wheel 36 that meshes with the worm 35 provided on the rotating shaft 34, and the rack 30 that meshes with the pinion 28 is driven. Thus, the steering torque applied by the driver to the steering wheel 11 is assisted by the assist motor M.

  As shown in FIG. 4, in a free state where the load F of the spring 33 is not acting, the radius R2 of the second sliding surface 31a of the rack guide 31 centered on O2 is the radius R2 of the rack bar 29 centered on O1. It is set slightly smaller than the radius R1 of the first sliding surface 29a. Therefore, the center O1 of the rack bar 29 and the center O2 of the rack guide 31 do not coincide with each other, and the first sliding surface 29a and the second sliding surface 31a are both tip portions a, a. In this case, only line contact is made and no surface contact is made.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the driver operates the steering wheel 11, the steering torque is transmitted to the rack 30 via the upper steering shaft 12, the upper universal joint 13, the lower steering shaft 14, the lower universal joint 15, the pinion shaft 17 and the pinion 28, and the steering gear. The rack bar 29 is driven in the left-right direction inside the box 18. At this time, when the assist motor M is activated, the assist torque is transmitted to the pinion shaft 17 via the worm 34 and the worm wheel 36, and the driver's steering operation is assisted.

  As shown in FIG. 3, the rack guide 31 is actually urged toward the rack bar 29 by the load F of the spring 33, so that the leading ends a and a of the rack guide 31 are the first of the rack bar 29. The center O1 of the first sliding surface 29a of the rack bar 29 is centered O2 of the second sliding surface 31a of the rack guide 31 by being elastically deformed in directions away from each other (see arrow b) guided by the sliding surface 29a. And the radius R2 of the second sliding surface 31a of the rack guide 31 expands to match the radius R1 of the first sliding surface 29a of the rack bar 29, and the first and second sliding surfaces 29a, 31a. Are in surface contact so that they are in close contact with each other.

  At this time, due to the stepped notches 31b and 31b formed on the outer peripheral portions of the both end portions a and a of the second sliding surface 31a, the thickness in the vicinity of the upper and lower end portions a and a of the rack guide 31 is increased. Not only can the size of the rack guide 31 be reduced, the vicinity of both ends a, a of the rack guide 31 can be easily elastically deformed in the direction of the arrow b, but both ends of the rack guide 31 can be elastically deformed in the vertical direction. When it does, it can avoid interfering with the inner surface of the guide hole 21a of the lower housing 21. FIG.

  As described above, according to the present embodiment, the first sliding surface 29a of the rack bar 29 and the second sliding surface 31a of the rack guide 31 are in surface contact with each other, so that the first and second sliding surfaces can be obtained. 29a and 31a do not wear unevenly, and the generation of noise due to backlash of the first and second sliding surfaces 29a and 31a can be prevented.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the outer peripheral portions of both tip portions a and a are stepped so that the lower housing 21 does not obstruct the vertical expansion of both tip portions a and a of the second sliding surface 31a. In the second embodiment, instead of forming the notches 31b and 31b, a recess 21b is formed on the side of the lower housing 21 facing both the tip portions a and a. , 21b. The effect of avoiding interference between the rack guide 31 and the lower housing 21 of the present embodiment is the same as that of the first embodiment.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  The third embodiment is a modification of the first embodiment. While the notches 31a and 31a of the rack guide 31 of the first embodiment have a stepped shape, the third embodiment is different from the first embodiment. The notches 31a and 31a of the rack guide 31 are different only in that they are tapered, but the effects are the same.

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  The fourth embodiment is characterized by the shape of the rack guide 31, and the other structure is the same as that of the third embodiment. That is, in the third embodiment, the second sliding surface 31a of the rack guide 31 is configured by a single arc surface having a common center O2, whereas the rack guide of the fourth embodiment. The second sliding surface 31a of 31 has centers O2, O2 in which the upper part and the lower part are different across the axis L. More specifically, the center O2 of the second sliding surface 31a on the upper side of the axis L is slightly biased to the lower side of the axis L, and the center O2 of the second sliding surface 31a on the lower side of the axis L is the axis. It is slightly biased to the upper side of L, and the two second sliding surfaces 31a are connected in a bent state at a virtual contact c on the axis L. The radius R of the first sliding surface 29a of the rack bar 29 and the radius R of the second sliding surface 31a of the rack guide 31 are set to be the same.

  Therefore, in the free state shown in FIG. 7 (the state in which the spring force F of the spring 33 does not act), the leading ends a of the second sliding surface 31a are in line contact with the first sliding surface 29a. However, in a use state in which the elastic force F of the spring 33 acts, the tips a and a of the two second sliding surfaces 31a center on the contact point c and elastically deform in a direction away from each other and expand. Thus, the first and second sliding surfaces 29a and 31a can be brought into surface contact with each other to prevent the occurrence of uneven wear.

  Next, a fifth embodiment of the present invention will be described with reference to FIG.

  The fifth embodiment is a modification of the first embodiment, and two notches 31b and 31b are formed on the radially outer side of the tip end portions a and a of the second sliding surface 31a of the rack guide 31. Is done. The operation of the notches 31b and 31b is the same as the notches 31b and 31b of the first embodiment described with reference to FIG.

  Since the rack guide 31 is slidably guided in the guide hole 21a formed in the lower housing 21, the length of the rack guide 31 guided in the guide hole 21a is reduced by the amount of the notches 31b and 31b. As a result, the original L1 is changed to L2, and the smooth sliding of the rack guide 31 may be hindered.

  Therefore, in the present embodiment, the pipe 37 fitted to the outer periphery of the rack guide 31 is slidably guided to the guide hole 21a of the lower housing 21, so that the guide length is increased to the original L1. The guide 31 can be smoothly slid.

  Next, a sixth embodiment of the present invention will be described with reference to FIG.

  The sixth embodiment is a modification of the fifth embodiment, and in the fifth embodiment, the rack guide 31 and a separate pipe member 37 are used, but in the sixth embodiment, the above-described pipe member 37 is used. A pipe member 37 is formed integrally with the rack guide 31. With this configuration, the number of parts can be reduced by the amount of the pipe member 37.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, although the shaft type steering device is exemplified in the embodiment, the present invention can be applied to a cable type steering device and a steer-by-wire type steering device. Of course, not only the electric steering apparatus having the assist motor M but also a manual steering apparatus having no assist motor M may be used.

1 is an overall perspective view of an electric power steering apparatus according to a first embodiment. 2-2 line enlarged sectional view of FIG. Part 3 enlarged view of FIG. The figure which shows the shape in the free state of a rack bar and a rack guide The figure corresponding to the said FIG. 3 and FIG. 4 based on 2nd Embodiment. The figure corresponding to the said FIG. 4 based on 3rd Embodiment The figure corresponding to the said FIG. 4 based on 4th Embodiment The figure corresponding to the said FIG. 4 based on 5th Embodiment The figure corresponding to the said FIG. 4 based on 6th Embodiment FIG. 3 is a diagram corresponding to FIG. 3 according to the conventional example.

11 Steering wheel 18 Steering gear box 21 Lower housing (housing)
21a Guide hole 21b Notch 28 Pinion 29 Rack bar 29a First sliding surface 30 Rack 31 Rack guide 31a Second sliding surface 31b Notch 33 Spring (elastic member)
a Tip of second sliding surface c Contact (intermediate part of second sliding surface)
R Radius R1 of the first and second sliding surfaces R1 Radius of the first sliding surface R2 Radius of the second sliding surface WL Wheel WR Wheel

Claims (6)

A steering gear box (18) that transmits the operation of the steering wheel (11) to the wheels (WL, WR) includes a pinion (28) connected to the steering wheel (11) and a rack that meshes with the pinion (28). A rack bar (29) connected to the wheels (WL, WR), a housing (21) that slidably supports the rack bar (29), and a housing (21) A rack guide (31) slidably fitted in the formed guide hole (21a), and a first arc-shaped cross section formed on the back surface of the rack bar (29) by biasing the rack guide (31). A rack and pinio comprising a resilient member (33) that abuts the second sliding surface (31a) having an arcuate cross section formed at the tip of the rack guide (31) on the sliding surface (29a). In the formula steering device,
A notch (31b) for reducing the wall thickness is formed on the outer peripheral surface on the both end portions (a) side of the second sliding surface (31a) of the rack guide (31), and the elastic member ( 33), when the second sliding surface (31a) is pressed against the first sliding surface (29a), first, both end portions (a) of the second sliding surface (31a) are A rack-and-pinion type steering device that abuts against one sliding surface (29a) . A steering gear box (18) that transmits the operation of the steering wheel (11) to the wheels (WL, WR) includes a pinion (28) connected to the steering wheel (11) and a rack that meshes with the pinion (28). A rack bar (29) connected to the wheels (WL, WR), a housing (21) that slidably supports the rack bar (29), and a housing (21) A rack guide (31) slidably fitted in the formed guide hole (21a), and a first arc-shaped cross section formed on the back surface of the rack bar (29) by biasing the rack guide (31). A rack and pinio comprising a resilient member (33) that abuts the second sliding surface (31a) having an arcuate cross section formed at the tip of the rack guide (31) on the sliding surface (29a). In the formula steering device,
On the inner peripheral surface of the guide hole (21a) facing the outer peripheral surface on the both end portions (a) side of the second sliding surface (31a) of the rack guide (31), the second sliding surface (31a). A rack-and-pinion type steering device, characterized in that a notch (21b) is formed in order to escape both of the front end portions (a). When the second sliding surface (31a) is pressed against the first sliding surface (29a) by the elastic member (33), first, both end portions of the second sliding surface (31a) ( The rack-and-pinion steering device according to claim 2, wherein a) abuts on the first sliding surface (29a). Identical to the radius (R) of the previous SL rack guide (31) second sliding surface which tip is formed in contact with the first sliding surface (29a) of (31a) said first sliding surface (29a) And the second sliding surface (31a) is bent at the intermediate portion (c) so that both tip portions (a) approach each other, and the rack guide (31) The rack and pinion type steering device according to any one of claims 1 to 3, wherein the first and second sliding surfaces (29a, 31a) are in surface contact by elastic deformation. Than the radius (R1) of the previous SL rack guide (31) second sliding surface which tip is formed in contact with the first sliding surface (29a) of (31a) is first sliding surface (29a) The first and second sliding surfaces (29a, 31a) are in surface contact by elastic deformation of the rack guide (31), having a slightly smaller radius (R2). The rack and pinion type steering apparatus according to any one of claims 3 to 4 . Than the radius (R1) of the previous SL rack guide (31) second sliding surface which tip is formed in contact with the first sliding surface (29a) of (31a) is first sliding surface (29a) The first and second sliding surfaces (29a, 31a) are in surface contact by elastic deformation of the rack guide (31), and are formed with a slightly smaller radius (R2). The rack and pinion type steering device according to any one of claims 1 to 3 .

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