Referring now to the drawings, there is illustrated in
The steering gear housing 12 also houses a rack 20. The rack 20 includes rack gear teeth 22 that mesh with the pinion gear 16 within the steering gear housing 12 for laterally displacing the rack 20 when the input shaft 14 is rotated. The opposite ends of the rack 20 each include a ball and socket joint (not shown) for pivotably connecting tie rods (not shown) to the rack 20. The tie rods are connected to steerable wheels (not shown) for steering the vehicle via the driver's manual input commands to the steering wheel.
The steering assembly 10 further includes a rack tube 24 that overlaps with the steering gear housing 12. The rack tube 24 is sealingly coupled to the steering gear housing 12. The rack tube 24 also houses a portion of the rack tube 24 and steering gear housing 12. A piston 26 is affixed about an outer diameter of the rack 20 within the rack tube 24. A first rack seal 28 is disposed within the rack tube 24 at an end of the steering gear housing 12. A chamber 30 is formed in cooperation with the inner wall of the rack tube 24, rack seal 28, and piston 26. A first adapter fitting 32 is affixed to the rack tube 24 at a region where the rack tube 24 and steering gear housing 12 overlap. The first adapter fitting 32 is also coupled to a hydraulic fluid line 34 for allowing hydraulic fluid flow to and from the chamber 30 via a venturi passage (shown in
The first adapter fitting 32, having a bore therethrough, is affixed to the rack tube 24 and extends radially therefrom. The first adapter fitting 32 is preferably a weld stud that is welded to the rack tube 24. Alternatively, the first adapter fitting 32 may be affixed by other means, or integrally formed as part of the rack tube 24. An aperture 35 extends through the wall of the rack tube 24 at the point of attachment of the first adapter fitting 32. The axis of the aperture 35 is aligned with the axis of the bore of the first adapter fitting 32.
A steering gear housing main fluid channel 38 is formed circumferentially about an outer surface of the steering gear housing 12. A steering gear housing extended fluid channel 40 extends axially along the outer surface of the steering gear housing 12 from the main fluid channel to the chamber 30. In the preferred embodiment, the main fluid channel 38 extends the entire circumference about the outer surface of the steering gear housing 12. In alternative embodiments, the main fluid channel 38 extends about the outer surface of the steering gear housing 12 only between the first adapter fitting 32 and extended channel portion 40.
The main fluid channel 38 is axially aligned with the bore of the first adapter fitting 32 for allowing hydraulic fluid flow between the hydraulic pressure line 34 and the chamber 30. Preferably the extended fluid channel 40 is formed axially along an uppermost portion of the steering gear housing 12. Alternatively, the extended fluid channel 40 may be formed at a maximum of 45 degrees from the uppermost portion. Having the extended fluid channel 40 formed at or near the uppermost portion of the steering gear housing 12 allows entrapped gases to bleed out of the chamber 30 when hydraulic fluid is withdrawn from the chamber 30.
The venturi passageway formed by the main fluid channel 38 and the extended fluid channel 40 allows the first adapter fitting 32 and hydraulic pressure line 34 to be affixed at any circumferential location about the rack tube 24. This alleviates any concerns for packaging the first adapter fitting 32 and associated hydraulic pressure line 34 along the uppermost portion of the rack tube where an interference condition may exist. In addition, the venturi passageway allows the first adapter fitting 32 to be affixed to the rack tube 24 in the overlap region 27 between the rack tube 24 in the steering gear assembly 12 which is axially offset from the chamber 30. This eliminates any design standard requirement that the piston maintain a predetermined distance from the aperture 35 since the aperture is not formed directly about the chamber 30. The elimination of this restricted travel region allows a shorter steering gear to be produced relative to conventional steering gear assemblies, without a decrease in the distance the rack can travel.
In an alternative embodiment, the aperture through the rack tube and the adapter fitting may be axially offset from the main fluid channel. A secondary extended fluid channel may extend from the aperture and the adapter fitting to the main fluid channel for maintaining fluid communication between the fluid adapter fitting and the main fluid chamber.
The second adapter fitting 41, having a bore therethrough, is affixed to the rack tube 24 and extends radially therefrom. The second adapter fitting 41 is preferably a weld stud that is welded to the rack tube 24. Alternatively, the second adapter fitting 41 may be affixed by other means, or integrally formed as part of the rack tube 24. An aperture 48 extends through the wall of the rack tube 24 at the point of attachment of the second adapter fitting 41. The axis of the aperture 48 is aligned with the axis of the bore of the second adapter fitting 41.
A rack bushing main fluid channel 50 is formed circumferentially about an outer surface of the rack bushing 45. A rack bushing extended fluid channel 52 extends axially along the outer surface of the rack bushing 45 from the main fluid channel 50 to the second chamber 39. In the preferred embodiment, the main fluid channel 50 extends the entire circumference about the outer surface of the rack bushing 45. In alternative embodiments, the main fluid channel 50 extends about the outer surface of the rack bushing 45 only between the second adapter fitting 41 and extended fluid channel 52.
The main fluid channel 50 is axially aligned with the bore of the second adapter fitting 41 for allowing hydraulic fluid flow between the hydraulic pressure line 43 and the chamber 39. Preferably, the extended fluid channel 52 is formed axially along an uppermost portion of the steering gear housing 12. Alternatively, the extended fluid channel 52 may be formed at a maximum of 45 degrees from the uppermost portion. Having the extended fluid channel 52 formed at or near the uppermost portion of the rack bushing 45 allows entrapped gases to bleed out of the chamber 39 when hydraulic fluid is withdrawn from the chamber 39.
The venturi passageway formed by the main fluid channel 50 and the extended fluid channel 52 allows the adapter fitting 41 and hydraulic pressure line 43 to be affixed at any circumferential location about the rack tube 24. This alleviates any concerns for packaging the second adapter fitting 41 and associated hydraulic pressure line 43 along the uppermost portion of the rack tube where an interference condition may exist. In addition, the venturi passageway allows the second adapter fitting 41 to be affixed to the rack tube 24 in the overlap region 47 between the rack tube 24 in the rack bushing 45 which is axially offset from the chamber 39. This eliminates any design standard requirement that the piston maintain a predetermined distance from the aperture 45 since the aperture 45 is not formed directly about the chamber 39. The elimination of this restricted travel region allows a shorter steering gear to be produced relative to conventional steering gear assemblies, without a decrease in the distance the rack can travel.
The venturi passage of the rack bushing 45 functions in a substantially same manner as that described earlier for the venturi passage in the steering gear housing 12. It should be noted that either the venturi passage of the rack bushing 45 or the venturi passage of the steering gear housing 12 may be solely utilized in the steering assembly 10, or both venturi passages in the steering gear housing 12 and the rack bushing 45 may be utilized in a same respective steering assembly.
In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. For example, the venture passageway may be used on both fluid chambers of the steering gear assembly.
This application is a continuation-in-part of application Ser. No. 11/252,095 filed Oct. 17, 2005.
Number | Date | Country | |
---|---|---|---|
Parent | 11252095 | Oct 2005 | US |
Child | 11650200 | US |