KR20040031103A - Integral bushing assembly for a rack and pinion steering gear - Google Patents

Abstract

The vehicle rack and pinion steering apparatus 10 using fluid power includes a rack 40 connectable to a steering wheel of a vehicle, a housing 20 partially surrounding the rack 40 and forming a fluid chamber 39, Bushings 390 or 590 surrounding the rack 40, sleeves 420 or 620 for supporting the rack 40 to slide relative to the bushings, and a hermetic sealing member for sealing the fluid chamber 39 ( 370 or 570). The bushing 390 or 590 has opposing axial ends 391, 412 or 591, 612, the outer surface 394 or 594 of the bushing 390 or 590 and the inner surface 26 of the housing 20. It is fixed inside the housing 20 by the interference fit of the liver. Sleeve 420 or 620 extends between bushing 390 or 590 and rack 40. The sleeve 420 or 620 has at least one radially extending tab 431 or 631 contained within a corresponding recess 418 or 618 inside the bushing 390 or 590. Tabs 431 or 631 provide a positioning surface 441 or 641 for positioning the sleeve 420 or 620 relative to the bushing 390 or 590. The sealing member 370 or 570 is disposed adjacent the recessed surface 394 or 594 of the bushing 390 or 590.

Description

INTEGRAL BUSHING ASSEMBLY FOR A RACK AND PINION STEERING GEAR}

Conventional hydraulic racks and pinion power steering devices for vehicles have racks extending axially through a hydraulic cylinder or chamber inside a housing. The end of the rack projects axially outward from the end of the housing and is connected with a steering link connected to the steering vehicle wheel.

Inside the chamber, the piston is fixed to the rack. When the vehicle steering wheel rotates, it activates the hydraulic valve and pressurizes the hydraulic fluid against the piston. The force imposed by the hydraulic fluid moves the piston inside the chamber, causing the rack to move axially. As the rack moves axially, the steering link moves, causing the steering vehicle wheel to rotate.

In order to prevent hydraulic fluid from flowing out of the chamber, it is necessary to seal the end of the chamber through which the rack protrudes. It is also desirable to support the rack so that it can move in the axial direction within the chamber without compromising the integrity of the seal. Bushing assemblies are generally used for this purpose. In addition, it is known to surround the end of the chamber with a bellows attached to the housing to prevent moisture, dust or other contaminants from entering the housing.

A bushing structure that tightly couples the bushing to the flat, unprocessed end of the housing and the bellows with a minimum of individual members extends the service life of the bushing device, while reducing assembly time and manufacturing costs.

Related Applications

This application is part of US Patent Application No. 09 / 961,838, filed on September 24, 2001, assigned to the assignee of the present invention.

Technical field

The present invention relates to a rack and pinion power steering device, and more particularly to a bushing assembly for a rack and pinion steering device.

These and other features of the present invention will become apparent to those skilled in the art to which the present invention pertains with reference to the following description in conjunction with the accompanying drawings.

1 is a schematic diagram of a rack and pinion power steering apparatus embodying the present invention.

2 is an enlarged cross-sectional view of a portion of the power steering apparatus of FIG. 1 showing a bushing assembly constructed in accordance with an aspect of the present invention.

3 is a cross-sectional view taken along line 3-3 of FIG.

4 is an enlarged cross-sectional view of a portion of the power steering apparatus of FIG. 1 showing a bushing assembly constructed in accordance with another feature of the present invention.

5 is a cross-sectional view taken along the line 5-5 of FIG.

6 is an enlarged cross-sectional view of a portion of the power steering apparatus of FIG. 1 showing a bushing assembly constructed in accordance with another feature of the present invention.

7 is a cross-sectional view taken along line 7-7 of FIG.

According to an aspect of the present invention, a vehicle rack and pinion steering apparatus using fluid power includes a rack connectable to a steering wheel of a vehicle, a housing partially enclosing the rack to form a fluid chamber, and enclosing and opposing the rack. A bushing having an axial end thereof, a sleeve supporting the rack to slide with respect to the bushing, and an oiltight sealing member for sealing the fluid chamber. The rack has a longitudinal axis and is movable in opposite axial directions to rotate the steering wheel in opposite directions. The bushing is fixed to the housing by an interference fit between the outer surface of the bushing and the inner surface of the housing. The sleeve is disposed between the bushing and the rack and engages the rack. The sleeve also has at least one radially extending tab received in at least one corresponding recess inside the bushing. The at least one radially extending tab positions the sleeve axially and rotatably with respect to the bushing.

According to another feature of the present invention, a vehicle rack and pinion steering apparatus using fluid power includes a rack connectable to a steering wheel of a vehicle, a housing partially enclosing the rack to form a fluid chamber, and a bushing surrounding the rack. And a sleeve for supporting the rack so as to slide relative to the bushing, and a umic sealing member for sealing the fluid chamber. The rack has a longitudinal axis and is movable in opposite axial directions to rotate the steering wheel in opposite directions. The housing has at least one distal end having a cylindrical inner surface of constant internal diameter. The bushing has an outer surface that engages with the inner surface of the housing. The bushing also has a first end and a second end axially opposite. The sleeve has at least one radially extending tab received in at least one corresponding recess at the second end of the bushing. The at least one radially extending tab positions the sleeve axially and rotatably with respect to the bushing. The sealing member is disposed inside the recess at the first end of the bushing.

The present invention relates to a rack and pinion power steering device, and more particularly to a bushing assembly for a rack and pinion power steering device. However, the present invention can be applied to various steering apparatus structures. As a representative example of the invention, FIG. 1 shows a rack and pinion power steering 10. The steering device 10 comprises a pair of steerable vehicle wheels (not shown) in a known manner by means of a steering link 12 at one end of the steering device and a similar steering link (not shown) at the other end of the steering device. Combined.

The steering apparatus 10 comprises a housing 20 having a longitudinal axis 21, a piston 14, a rack 40 having the same longitudinal axis as the housing, and a bushing assembly 60 according to one feature of the invention. Equipped. The housing 20 has a pinion portion 24 extending laterally with the rack portion 22. The pinion portion 14 is disposed inside the pinion portion 24 of the housing 20 and is toothed with a tooth (not shown) on the rack 40 at the point where the pinion portion and the rack portion 22 intersect within the housing. It has a tooth (not shown) to join.

As shown in FIGS. 2 and 3, the rack portion 22 of the housing 20 has a cylindrical inner surface 26 and a cylindrical outer surface 28, the inner and outer surfaces having a longitudinal axis 21. It is centered around. The housing 20 also has a first end 31 and a second end 32 opposite the first end (FIG. 1). Both the inner face 26 and the outer face 28 have a constant diameter such that they form a uniform cylinder at the ends 31, 32 of the housing 20. The annular end face 30 of the housing 20 extends between the inner face 26 and the outer face 28 at the first end 31 of the housing 20. The inner surface 26 in the rack portion 22 also forms a fluid chamber 39 inside the housing 20.

The rack 40 is centered on the longitudinal axis 21 and extends axially through the fluid chamber 39 inside the housing 20. Opposite end portions 42, 44 (FIG. 1) of rack 40 project axially past each of end portions 31, 32 of housing 20 to engage a steering link (not shown). The rack 40 has a cylindrical outer surface 46 partially disposed within the fluid chamber 39 and partially surrounded by the housing 20. Each of the distal ends 42, 44 of the rack 40 extends axially outward from the housing 20.

Inside the fluid chamber 39, a piston (not shown) is fixed to the rack 40. As the vehicle steering wheel (not shown) rotates, fluid in pressurized state within the fluid chamber 39 operates against the piston, causing the rack 40 to move axially within the housing 20. When the rack 40 is thus axially moved in the opposite direction, the steering link 12 moves in the opposite direction, so that the steerable vehicle wheel rotates in the opposite direction as shown.

The bushing assembly 60 is disposed at the first end 31 of the housing 20. Similar bushing assemblies (not shown) may be disposed at the second end 32 of the housing 20. Bushing assembly 60 encloses rack 40 and is centered on axis 21. The bushing assembly 60 is connected to the housing 20 and supports the rack 40 to axially move relative to the housing. Bushing assembly 60 also seals fluid chamber 39 to prevent fluid from leaking from housing 20. The housing assembly 60 has an annular sealing member 70, an annular bushing 90, and a cylindrical liner or sleeve 110.

Bushing 90 is disposed inside fluid chamber 39 and extends radially between housing 20 and sleeve 110. Bushing 90 also extends axially from the end face of housing 20 to fluid chamber 39 and outwardly in another opposite axial direction along distal end 42 of rack 40. Bushing 90 encloses an outer surface 46 of rack 40 but does not engage the outer surface thereof. The bushing 90 has a cylindrical inner surface 92 and an outer surface 94, respectively. Thus, the inner surface 92 of the bushing 90 does not engage and is radially spaced apart from the outer surface 46 of the rack 40.

The bushing 90 also has a second section 112 axially opposite the first section 91. The first section 91 extends axially along the inner face 26 of the housing 20 from the end face 30 of the bushing. The first section 91 of the bushing 90 may be fixed inside the housing 20 only by an interference fit between the outer surface 94 of the bushing 90 and the inner surface 26 of the housing. Thereby, the first section 91 of the bushing 90 forms the axial end of the fluid chamber 39.

This interference fit allows the bushing assembly 60 to be secured to the housing 20 without the need for other fastening features (ie, fastening wires, fastening rings, housing crimps, etc.). In addition, the distal ends 31, 32 of the housing 20 can be formed with flat cylindrical tube ends without the need for additional modifications (ie, machining, tapering, forming, crimping, etc.). However, the distal ends 31 and 32 may optionally be modified to include crimping, crimping pads, etc. to increase the bond provided by the interference fit. The interference fit is usually achieved by the outer diameter of the bushing 90, which is about 0.2 mm larger than the inner diameter of the housing 20.

The first section 91 of the bushing 90 additionally forms a first recess 93 for receiving the sealing member 70. Bushing 90 may be made of a metal material such as zinc, zinc alloy (ie, ZAMAK 5), metal powder or cast aluminum.

The sleeve 110 is preferably fitted to the second recess 95 on the cylindrical inner surface 92 of the bushing to form a single integral part with the bushing 90. Sleeve 110 supports rack 40 to slide relative to housing 20 and bushing 90. The sleeve 11 also provides a support surface between the axially moving rack 40 and the relatively fixed bushing 90 to reduce wear between the relatively moving parts. Sleeve 110 may be made of a polymeric composite material such as 35% glass filled polyester (RYNITE tradename polyester or KEVLAR / TEFLON, available from E.I Dupont de Nemours & Co.).

A fluid seal (oiltight) annular seal member is attached to the first section 91 of the bushing 90 to provide a oiltight seal to the fluid chamber 39 of the housing 20. The sealing member 70 is typically made of an elastomeric material such as VITON® or hydrogenated NITRILE®. The sealing member 70 has a cylindrical inner sealing face 72 and a cylindrical outer sealing face 74, respectively. The outer surface 74 of the sealing member 70 sealingly engages with the inner surface 26 of the housing 20. The inner surface 72 of the sealing member 70 sealingly engages with the outer surface 46 of the rack 40 that is axially movable relative to the sealing member.

The sealing member 70 has first, second and third surfaces 81, 82, 83, each of which has a first annular surface at the axial end of the first section 91 of the bushing 90. 101, abut the second recessed annular surface 102 and the third recessed cylindrical surface 103. The sealing member 70 is preferably fixed to the bushing 90 by pressing the sealing member into a recess 93 formed by the surfaces 101, 102, 103 inside the first section 91 of the bushing.

The first surface 81 of the sealing member 70 sealingly engages the first surface 101 of the bushing 90. Sealingly engage the second surface 102 of the bushing 90 of the sealing member 70. The third surface 83 of the sealing member 70 sealably engages with the third surface 103 of the bushing 90. The seal never imposes an axial force on the sealing member (ie, during the axial movement of the rack 40) so that the sealing member does not separate from the position inside the recess 93 of the bushing 90. It is preferred that there is a small gap between the second surface 83 of the member 70 and the sleeve 110.

The sealing member 70 also has an annular groove 85, in which a metal garter spring 86 is arranged. The garter spring 86 exerts a radially inward force on a portion of the sealing member 70 such that the inner surface 72 of the sealing member abuts against the outer surface of the rack 40 and moves intermittently with the sealing member. Maintain a hermetic seal between racks.

The first and second sections 91, 122 of the bushing 90 are formed together as a single member, which is made of a single homogeneous material in a single unit rather than the individual parts in which the first and second sections are joined together. It means to be. The second section 112 of the bushing 90 protrudes axially beyond the end face 30 of the housing 20. The second section 112 has an annular surface 113 which acts as a surface for positioning the bushing. The surface 113 abuts the end face 30 of the housing 20 to determine the position of the bushing 90 relative to the housing 20. The second section 112 also has a cylindrical outer surface 115 having a diameter substantially the same as the diameter of the outer surface 28 of the distal end 31 of the housing 20. The first section 112 of the bushing 90 has an annular retaining ridge 114 (FIG. 2) extending in the circumferential direction. The retaining ridge 114 extends radially from the outer surface 115 and has a semi-cylindrical cross-sectional shape. The retaining ridge 114 is typically formed of a single member with the bushing 90.

The steering apparatus 10 also has a bellows member 200 which encloses the rack 40 and which surrounds the second section 112 of the bushing 90 and the distal end of the rack 40. The bellows member 200 is made of a suitable flexible material such as rubber. The bellows member 200 is attached to the second section 112 of the bushing 90. Bellows member 200 has an inner surface 202, an outer surface 204, and an end 206. The inner surface 202 of the bellows member 200 is provided with a groove 208 extending in the circumferential direction, which is provided on the bushing 90 to assist in securing the bellows member with respect to the bushing and the housing 20. The retaining ridge 114 formed is received.

An annular band clamp 210 surrounds the outer surface 28 of the distal end 31 of the housing 20. The band clamp 210 compresses the end 206 of the bellows member 200 against the housing 20 to assist in securing the bellows member relative to the bushing 90 and the housing. By attaching the bellows member 200 to the flat outer surface 28 of the housing 20 and the bushing 90 itself, the housing can be easily manufactured because the bellows retaining features do not need to be incorporated into the distal end 31 of the housing. Can be. Accordingly, the present invention provides an integral bushing assembly 60 that seals the fluid chamber 39, supports the rack 60 to slide, and reliably retains the bellows member 200.

4 and 5 illustrate a bushing assembly 360 in accordance with another aspect of the present invention. The bushing assembly 360 is disposed at the first distal end 36 of the housing 20. Similar bushing assemblies (not shown) may be disposed at the second distal end 32 of the housing 20. Bushing assembly 360 surrounds rack 40 and is centered on axis 21. Bushing assembly 360 is coupled to housing 20 and supports rack 40 to axially move relative to the housing. Bushing assembly 360 also seals fluid chamber 39 to prevent fluid from leaking from housing 20. Bushing assembly 360 includes a first annular sealing member 370, a second annular sealing member 380, an annular bushing 390, and a cylindrical liner or sleeve 420.

Bushing 390 is disposed inside fluid chamber 39 and extends radially between bushing 20 and sleeve 420. Bushing 390 may be made of a metal material, such as zinc, zinc alloy (ie, ZAMAK 5), metal powder, or cast aluminum. The bushing 390 also extends in one axial direction from the end face 30 of the housing 20 to the fluid chamber 39 and outwardly in another opposite axial direction along the distal end 42 of the rack 40. do. Bushing 390 surrounds the outer surface 46 of rack 40 but does not engage with the outer surface. Bushing 390 has a cylindrical inner surface 392 and a cylindrical outer surface 394, respectively. Thus, the inner surface 392 of the bushing 390 does not engage and is radially spaced apart from the outer surface 46 of the rack 40.

The bushing 390 also has a second section 412 opposite in the axial direction to the first section 391. The first section 391 extends axially along the inner surface 26 of the housing 20 from the end face 30 of the bushing. The first section 391 of the bushing 390 may be secured inside the housing 20 only by an interference fit between the outer surface 394 of the bushing 390 and the inner surface 26 of the housing. The first section 391 of the bushing 390 forms the axial end of the fluid chamber 39.

The bushing 390 may have two annular recesses or grooves 396, 398 formed on the outer surface 394 of the bushing 390. The first groove 390 is located inside the first section 391 of the bushing 390, and the second groove 398 is axially spaced from the first groove inside the first section of the bushing. The grooves 396 and 398 extend in the circumferential direction around the outer circumferential surface of the bushing 390.

The interference fit described above allows the bushing assembly 360 to be secured to the housing 20 without the need for other fastening features (ie, fastening wires, fastening rings, housing crimps, etc.). However, as shown in FIG. 4, the bushing assembly 360 may be supplementally secured within the housing 20 by crimping the housing 20.

The material of the housing 20 may be deformed radially inward to secure the bushing 390 inside the housing. More specifically, the material of the housing 20 may include a second groove 398 inside the first section 391 of the bushing 390 at individual points 29 (two points shown) around the circumference of the housing. Is crimped radially inward. Coupling the deformed material of the housing 20 within the second groove 398 of the bushing 390 secures the bushing axially within the housing.

In addition, due to the interference fit (and crimp housing), the distal ends 31 and 32 of the housing 20 can be formed into flat cylindrical tube ends without the need for any further modification (machining, tapering, forming, etc.). The interference fit is typically provided by the outer diameter of the bushing 390 which is typically about 0.2 mm larger than the inner diameter of the housing 20.

The first section 391 of the bushing 390 also has a cylindrical recess 393 to receive a portion of the first sealing member 370 and the sleeve 420. The first recess 393 is defined by a cylindrical sealing surface 399 and an annular support surface 395 extending radially.

The sleeve 420 is preferably clipped on the inner surface 392 of the bushing 390 to form a single integral part with the bushing 390. The sleeve 420 supports the rack 40 to slide relative to the housing 20 and the bushing 390. The sleeve 420 is also between the rack 40 and the fixed bushing 90 moving axially. Provides a support surface to reduce wear between relatively moving parts. The sleeve 420 may be made of a polymeric composite material such as 35% glass filled polyester (RYNITE brand polyester or KEVLAR / TEFLON, available from E.I Dupont de Nemours & Co.).

The sleeve 420 generally has a cylindrical shape with a second end 422 facing axially with the first end 421. The first end 421 has a flange 424 extending radially. The flange 424 has an annular first surface 426 and an annular second surface 428 opposite the first surface. As shown in FIG. 5, the second end 422 of the sleeve 420 extends radially disposed at radially opposite points from the first tab 431 extending radially and the first tab 431. The second tab 432 is provided.

The first tab 431 has a radially extending first surface 441 (FIG. 4) and a radially extending (or angular) second end surface 442 axially spaced from the first surface. Has The second tab 432 has a first surface 451 extending radially and a second end surface extending radially (or angularly) axially spaced from the first surface.

In the assembly process, the sleeve 420 is inserted into the bushing 390. The tabs 431, 432 deflect radially inward as the sleeve 420 moves axially relative to the bushing 390. The sleeve 420 is inserted into the first section 412 and the second until the tabs 431, 432 reach the second section 412 and are received in the corresponding slots 418 inside the bushing 390. Move axially towards the section. Tabs 431 and 432 snap radially outwardly into slot 418 inside bushing 390. Tabs 431 and 432 and slots 418 are sized so that the tabs fit snugly into the slots. The manufacturing tolerance between the tabs 431, 432 and the slot 418 is on the order of 0.005 to 0.010 inches.

The angled surfaces 442, 452 of the tabs 431, 432 facilitate the insertion of the sleeve 420 relative to the bushing 390 and facilitate the axial movement of the sleeve 420 through the bushing 390. do. The angled surfaces 442, 452 initially engage the support surface 395 of the bushing 390. The support surface 395 forms a cam on the tabs 431, 432 radially inward when the sleeve 420 is inserted into the bushing 390. An axial slot 433 is provided on either side of the tabs 431, 432 to facilitate radial deflection of the tab during insertion of the sleeve 420 to the bushing 390.

The sleeve 420 snaps the tabs 431, 432 into the slot 418 formed in the bushing, while the second surface 428 of the sleeve's flange 424 supports the support surface 395 of the bushing 390. It is desirable to have a size that can be bonded to (or axially) abutment. The distance between the first surface 428 of the flange 424 and the first surface 441, 451 of the tabs 431, 432 is equal to the distance between the support surface 395 of the bushing 390 and the slot 418 of the bushing. Do.

Thus, the sleeve 420 is fixed axially with respect to the bushing 390 by the second surface 428 of the flange 424 and by the first surfaces 441 and 451 of the caps 431 and 432 of the sleeve. And arranged. In addition, the sleeve 420 is rotatably fixed and disposed relative to the bushing 390 by tabs 431 and 432 that fit tightly within the slot 418 of the bushing.

The fluid sealing first sealing member 370 is attached to the first section 391 of the bushing 390 and provides a hermetic seal for the fluid chamber 39 of the housing 20. The first sealing member 370 is typically made of an elastomeric material, such as VITON® or hydrogenated NITRILE®. The inner surface 372 of the first sealing member 370 sealingly engages with the outer surface 46 of the rack 40 that is axially movable relative to the sealing member.

The first sealing member 370 has first and second surfaces 374 and 376, respectively. The first surface 374 is cylindrically and sealingly engaged with the cylindrical sealing surface 399 of the first recess 393. The second surface 376 extends radially and is annular. The second surface 376 abuts the first annular surface 426 of the flange 424 of the sleeve 420. The hydraulic pressure discharged from the chamber 39 helps to maintain the first sealing member 370 in abutment (or axial) engagement with the flange 424 of the sleeve 420 during operation of the steering apparatus 10.

The first sealing member 370 may additionally include an annular groove 378 in which a metal garter spring 379 is disposed. The garter spring 379 imposes a radially inwardly directed force on a portion of the first sealing member 370 such that the inner surface 372 of the first sealing member is against the outer surface 46 of the rack 40. A fluid tight seal is maintained between the pressurized and intermittently moving rack.

The first and second sections 391, 412 of the bushing 390 are mutually formed as a single member, which is a single member rather than an individual component to which the first and second sections are joined to each other as a single homogeneous material. It means to be manufactured.

The second section 412 of the bushing 390 protrudes axially past the end face 30 of the housing 20. The second section 412 has an annular surface 413 that acts as a bushing positioning surface. The surface 413 abuts the end face 30 of the housing 20 to determine the position of the bushing 390 relative to the housing 20. The second section 412 also has a cylindrical outer surface 415 having a diameter approximately equal to the diameter of the outer surface 28 of the inner end 31 of the housing 20. The second section 412 of the bushing 390 has an annular retaining ridge 414 (FIG. 4) extending circumferentially to receive the bellows member 200 as described above. Retaining ridge 414 extends radially from outer surface 415 and has a semi-cylindrical cross section. The retaining ridge 414 is formed of a single member with the bushing 390.

The second sealing member 380 may be an O-shaped ring disposed inside the first section 391 of the bushing 390. The second sealing member 380 sealingly engages the first groove 396 and the surface defining the inner surface 26 of the housing 20, such that fluid flows out of the chamber 39 along the inner surface of the housing. Block it. The O-shaped ring may be made of neoprene or other suitable material.

6 and 7 illustrate a bushing assembly 560 according to another feature of the present invention. The bushing assembly 560 is disposed at the first distal end 36 of the housing 20. Similar bushing assemblies (not shown) may be disposed at the second distal end 32 of the housing 20. Bushing assembly 560 surrounds rack 40 and is centered on axis 21. Bushing assembly 560 is coupled to housing 20 and supports rack 40 to axially move relative to the housing. Bushing assembly 560 additionally seals fluid chamber 39 to prevent fluid from leaking from housing 20. Bushing assembly 560 includes a first annular sealing member 570, a second annular sealing member 580, an annular bushing 590, and a cylindrical liner or sleeve 620.

Bushing 590 is disposed inside fluid chamber 39 and extends radially between housing 20 and sleeve 620. Bushing 590 may be made of a metal material such as zinc, zinc alloy (ie, ZAMAK 5), metal powder or cast aluminum. The bushing 590 extends axially from the end face 30 of the housing 20 into the fluid chamber 39 and from the end face of the housing to the outward axis along the distal end 42 of the rack 40. Extend in the direction. Bushing 590 surrounds outer surface 46 of rack 40 but does not engage outer surface 46. Bushing 590 has a cylindrical inner surface 592 and a cylindrical outer surface 594, respectively. Thus, the inner surface 592 of the bushing 590 does not engage and is radially spaced apart from the outer surface 46 of the rack 40.

The bushing 590 also has a second section 612 opposite in the axial direction to the first section 591. The first section 591 extends axially along the inner surface 26 of the housing 20 from the end face 30 of the bushing. The first section 591 of the bushing 390 may be secured inside the housing 20 by an interference fit between the outer surface 594 of the bushing 590 and the inner surface 26 of the housing. The first section 591 of the bushing 590 forms the axial end of the fluid chamber 39.

Bushing 590 may have two annular recesses or grooves 596, 598 formed on outer surface 594 of bushing 590. The first groove 596 is disposed inside the first section 591 of the bushing 590 and the second groove 598 is disposed inside the first section of the bushing. The grooves 596, 598 extend circumferentially around the outer periphery of the bushing 590.

This interference fit allows the bushing assembly 560 to be secured to the housing 20 without the need for other fastening features (ie, fastening wires, fastening rings, housing crimps, etc.). However, as shown in FIG. 6, the bushing assembly 560 may be complementarily fixed within the housing 20 by crimping the housing 20. More specifically, the material of the housing 20 can be deformed radially inward to secure the bushing 590 inside the housing.

The material of the housing 20 is crimped radially inward to the second groove 398 inside the first section 591 of the bushing 590 at individual points 29 (two points shown) around the circumference of the housing. do. Coupling the deformed material 29 of the housing 20 into the second groove 598 of the bushing 590 secures the bushing axially within the housing.

In addition, due to the interference fit (and crimp housing), the distal ends 31 and 32 of the housing 20 can be formed into flat cylindrical tube ends without the need for any further modification (machining, tapering, forming, etc.). The interference fit is typically provided by the outer diameter of the bushing 390 which is typically about 0.2 mm larger than the inner diameter of the housing 20.

The first section 591 of the bushing 590 also has a cylindrical recess 593 to receive a portion of the first sealing member 570 and the sleeve 620. First recess 593 is defined by cylindrical sealing surface 599 and annular support surface 595 extending radially.

The sleeve 620 is preferably cast on the inner surface 592 of the bushing to form a single integral part with the bushing 590. Sleeve 610 supports rack 40 to slide relative to housing 20 and bushing 590. The sleeve 620 also provides a support surface between the axially moving rack 40 and the relatively stationary bushing 90 to reduce wear between relatively moving parts. Sleeve 110 may be made of a polymeric composite material such as 35% glass filled polyester (RYNITE tradename polyester or KEVLAR / TEFLON, available from E.I Dupont de Nemours & Co.).

The sleeve 620 generally has a cylindrical shape with a second end 622 facing axially with the first end 621. The first end 621 has a flange 624 extending radially. The flange 624 has an annular first surface 626 and an annular second surface 628 opposite the first surface. As shown in FIG. 7, the second end 622 of the sleeve 620 has a plurality of (8 in FIG. 7) radially extending tabs 631, with paired tabs (four pairs shown). ) Are arranged at positions facing each other in the radial direction.

Tab 631 has a radially extending (or angular) first surface 641 and a radially extending second surface 642 extending perpendicular to the axis 21. The second surface 642 forms part of the distal face of the sleeve 620. The material of the sleeve 620 is cast on the inner surface 592 of the bushing 590 and the support surface 595 of the bushing. Thus, the sleeve is mounted to the bushing 590 such that the flange 624 of the sleeve 620 is formed on the support surface 595 of the bushing 590 and the tab 631 is formed inside the slot 618 inside the bushing. Have dimensions as much as

Slot 618 determines the shape of tab 631 when sleeve 620 is cast. Thereby, the sleeve 620 is stirred and positioned axially relative to the bushing 590 by the second surface 628 of the sleeve flange 624 and the first surface 641 of the sleeve tab 631. . Thus, the sleeve 620 is rotatably fixed and positioned relative to the bushing 590 by a tab 631 filling the slot 618 of the bushing.

A fluid sealed first sealing member 570 is attached to the first section 591 of the bushing 590 and provides a hermetic seal for the fluid chamber 39 of the housing 20. The first sealing member 570 is typically made of an elastomeric material, such as VITON® or hydrogenated NITRILE®. The first sealing member 570 has a cylindrical inner sealing surface 572. The inner sealing surface 572 of the first sealing member 570 sealingly engages with the outer surface 46 of the rack 40 that is axially movable relative to the sealing member.

The first sealing member 570 has first and second surfaces 574, 576, respectively. The first cylindrical surface 574 sealingly engages the cylindrical sealing surface 599 of the first recess 593. The second annular surface 576 is the first of the flange 524 to axially secure the first sealing member 570 (and the flange 624 of the sleeve 620) inside the first recess 593. Abuts with annular surface 526. The hydraulic pressure discharged from the chamber 39 helps to maintain the first sealing member 570 in abutment (or axial) engagement with the flange 624 of the sleeve 620 during operation of the steering apparatus 10.

The first sealing member 570 may additionally include an annular groove 578 in which the metal garter spring 579 is disposed. The garter spring 579 imposes a radially inwardly directed force on a portion of the first sealing member 570, such that the inner surface 572 of the first sealing member against the outer surface 46 of the rack 40. A fluid tight seal is maintained between the pressurized and intermittently moving rack.

The first and second sections 591, 612 of the bushing 590 are mutually formed as a single member, which is a single homogeneous material as a single member rather than as a separate part where the first and second sections are joined to each other. It means to be manufactured.

The second section 612 of the bushing 590 protrudes axially beyond the end face 30 of the housing 20. The second section 612 has an annular surface 613 that acts as a bushing positioning surface. The surface 613 abuts the end face 30 of the housing 20 to determine the position of the bushing 590 relative to the housing 20. The second section 612 also has a cylindrical outer surface 615 having a diameter approximately equal to the diameter of the outer surface 28 of the inner end 31 of the housing 20. The second section 612 of the bushing 590 has an annular retaining ridge 614 (FIG. 6) extending circumferentially to receive the bellows member 200 as described above. Retaining ridge 614 extends radially from outer surface 615 and has a semi-cylindrical cross section. The retaining ridge 614 is formed from the bushing 590 and a single member.

The second sealing member 580 may be an O-shaped ring disposed inside the first annular groove 596 formed inside the outer surface 594 of the first section 591 of the bushing 590. The second sealing member 580 sealingly engages the first groove 596 and the surface defining the inner surface 26 of the housing 20, so that fluid flows out of the chamber 39 along the inner surface of the housing. Block it. The O-shaped ring may be made of neoprene or other suitable material.

From the foregoing invention, one skilled in the art can recognize improvements, changes and modifications. These improvements, changes and modifications are intended to be protected by the claims.

Claims (25)

In a vehicle rack and pinion steering apparatus using fluid power, A rack connectable with a steering wheel of the vehicle, the rack having a longitudinal axis and movable in opposite axial directions for rotating the steering wheel in opposite directions; A housing partially enclosing the rack and forming a fluid chamber; A bushing surrounding the rack and having opposing axial ends, the bushing being secured to the housing by an interference fit between an outer surface of the bushing and an inner surface of the housing; A rack that supports the rack to slide relative to the bushing, extends between the bushing and the rack to engage the rack, and at least one radially extending tab housed in at least one corresponding recess within the bushing Wherein the at least one radially extending tab is adapted to axially and rotatably secure the sleeve with respect to a bushing; And A hermetic sealing member for sealing the fluid chamber Rack and pinion steering device comprising a. The rack and pinion steering apparatus of claim 1, wherein the bushing is radially spaced from the rack and the sleeve couples to the bushing and the rack. 2. The rack and pinion steering apparatus of claim 1, wherein the housing has at least one distal end, the distal end having an annular surface for abutting the surface of the bushing and for positioning the bushing relative to the housing. The rack and pinion steering apparatus of claim 1, wherein the sleeve has a flange extending radially to axially secure the sleeve to the bushing. The rack and pinion steering apparatus of claim 1, wherein the sleeve has a tab that snaps to the bushing during assembling the sleeve and the bushing. The rack and pinion steering apparatus of claim 1, wherein the sleeve is cast in a bushing prior to assembly of the apparatus. The rack and pinion steering apparatus of claim 1, further comprising a second hermetic sealing member for sealing the fluid chamber. In a vehicle rack and pinion steering apparatus using fluid power, A rack connectable with a steering wheel of the vehicle, the rack having a longitudinal axis and movable in opposite axial directions for rotating the steering wheel in opposite directions; A housing partially enclosing the rack and forming a fluid chamber, the housing having at least one distal end having a cylindrical inner surface having a constant inner diameter; A bushing surrounding the rack, the bushing having an outer surface engaging with the inner surface of the housing and a first end and an axially opposite second end; Support the rack to slide relative to the bushing, having at least one radially extending tab received in at least one corresponding recess at the second end of the bushing, the at least one radially extending The tab includes a sleeve that axially and rotatably secures the sleeve relative to the bushing; And A hermetic sealing member for sealing the fluid chamber disposed in the recess at the first end of the bushing Rack and pinion steering device comprising a. 9. The rack and pinion steering apparatus of claim 8, wherein the bushing has a retaining ridge for securing the bellows member to the bushing, wherein the retaining ridge is formed from the bushing and a single member. 9. The rack and pinion steering apparatus of claim 8, wherein the sleeve is made of a polymeric material. 11. The rack and pinion steering apparatus of claim 10, wherein the bushing is made of a metallic material. In a vehicle rack and pinion steering apparatus using fluid power, A rack connectable with a steering wheel of the vehicle, the rack having a longitudinal axis and movable in opposite axial directions for rotating the steering wheel in opposite directions; A housing partially enclosing the rack and forming a fluid chamber; A bushing surrounding the rack and having opposing axial ends, the bushing being secured to the housing by an interference fit between an outer surface of the bushing and an inner surface of the housing; A sleeve supporting the rack to slide relative to the bushing, the sleeve being biased against the first recess surface within the bushing having a first diameter and extending between the bushing and the rack to engage the rack; And A hermetic sealing member for sealing said fluid chamber, said axial end of said bushing disposed adjacent said second recessed surface, said second recessed surface having a second diameter greater than said first diameter, A hermetic sealing member for sealing the fluid chamber that encloses the rack and extends between the rack and the housing and sealingly couples to both the rack and the housing. Rack and pinion steering device comprising a. 13. The rack and pinion steering apparatus of claim 12, wherein the housing has at least one distal end having a cylindrical inner surface of constant internal diameter. 13. The rack and pinion steering apparatus of claim 12, wherein the sleeve has a cylindrical member fixed to a first recessed surface, the first recessed surface forming a cylinder. 13. The rack and pinion steering apparatus of claim 12, wherein the second recessed surface of the bushing partially forms a recess into which the sealing member is fitted. 13. The rack and pinion steering apparatus of claim 12, wherein the first recessed surface of the bushing partially forms a recess for pressing the sleeve. 13. The rack and pinion steering apparatus of claim 12, wherein the bushing is radially spaced from the rack. 13. The rack and pinion steering apparatus of claim 12, wherein the housing has at least one distal end, the distal end having an annular surface for abutting the surface of the bushing and for positioning the bushing relative to the housing. In a vehicle rack and pinion steering apparatus using fluid power, A rack connectable with a steering wheel of the vehicle, the rack having a longitudinal axis and movable in opposite axial directions for rotating the steering wheel in opposite directions; A housing partially enclosing the rack and forming a fluid chamber, the housing having at least one distal end having a cylindrical inner surface having a constant inner diameter; A bushing surrounding the rack, the bushing having an outer surface that engages with the inner surface of the housing; A sleeve supporting the rack to slide relative to the bushing, the sleeve being fitted into the first recess at the inner diameter of the bushing; And A hermetic sealing member for enclosing the rack and extending between the rack and the housing and disposed inside the second recess at the axial end of the bushing. Rack and pinion steering device comprising a. 20. The rack and pinion steering apparatus of claim 19, wherein the bushing has a retaining ridge for securing the bellows member to the bushing, wherein the retaining ridge is formed of a single member with the bushing. 20. The rack and pinion steering apparatus of claim 19, wherein the sleeve is made of a polymeric material. 22. The rack and pinion steering apparatus of claim 21, wherein the bushing is made of metal material. 20. The rack and pinion steering apparatus of claim 19, wherein the first recess is formed in part by a first recess surface on the bushing. 24. The rack of claim 23, wherein the second recess is formed in part by a second recess surface on the bushing, the second recess surface having a diameter greater than the diameter of the first recess surface. Pinion Steering Device. 20. The rack and pinion steering apparatus according to claim 19, wherein the bushing is fixed to the housing only by an interference fit between the outer surface of the bushing and the inner surface of the housing.