FORM 2
THE PATENT ACT 197 0 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION See Section 10, and rule 13)
TITLE OF INVENTION
JOINT ASSEMBLY FOR A VEHICLE

2. APPLICANT(S)
a) Name
b) Nationality
c) Address

ZF FRIEDRICHSHAFEN AG
GERMAN Company
8803 8 FRIEDRICHSHAFEN
GERMANY

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -


The invention relates to a joint assembly for a vehicle/ with a joint having a joint housing and^a joint journal which is mounted so as to be able to move relative to said joint housing, a rod which has a cavity and is connected to the joint, sealing bellows which delimit an interior and in which the joint is at least partly arranged, and a gas-permeable connection which connects the cavity of the rod to the interior of the sealing bellows and has at least one groove which is formed in an end face of the joint that faces the rod, opens into the interior and has a radially outer end.
Joint assemblies of this type are known in the art and are used for example for rack-and-pinion steering systems, the sealing bellows protecting at least a part of the joint assembly from environmental influences and soiling. Movements of the toothed rack can result within the sealing bellows in fluctuations in pressure which can be compensated for via the gas-permeable connection.
DE 43 31 291 C1 discloses a joint connection with a ball joint housing which is integrally connected to an axial connection journal which has an outer thread and is screwed into a hollow toothed rack having a corresponding inner thread. The toothed rack rests after mounting thereof against a radial flange with which the connection journal merges on the side of the ball joint housing. Ventilation grooves, which merge with the radial flange, are introduced into the connection journal.
JP 5-37644 discloses a connection between a hollow rod and a housing, a groove being introduced into the wall of the rod on the end face side. Furthermore, two opposing grooves are formed on the inner wall of the rod in the region of a thread.
JP 63-104173 discloses a joint assembly with a joint which is connected to a hollow rod via a screwed connection by means of a journal. Formed in the journal is an axial groove which runs in a thread and merges with a radial groove formed in a radial flange, which is provided with a key surface, of the journal.
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JP 3-8066 discloses a ball joint, the housing base of which has an axially set-back flange with an axially protruding journal which engages with a hollow rod. Radial grooves, which merge with axial grooves formed in the lateral surface of the journal, are introduced into the flange which is provided with a key surface.
A drawback of the last two solutions is that grooves extend through key surfaces, grooves producing in combination with key surfaces complex contours at which burrs or increased tool wear can occur.
Starting from this prior art, the invention is based on the object of developing the joint assembly mentioned at the outset in such a way as to allow complex contours, at which burrs or increased tool wear occur, to be avoided.
According to the invention, this object is achieved by a joint assembly according to claim 1. Preferred developments are provided in the sub-claims.
The joint assembly according to the invention for a vehicle, in particular a motor vehicle, has a joint having a joint housing and a joint journal which is mounted so as to be able to move relative to said joint housing, a rod which has a cavity and is connected to the joint, sealing bellows which delimit an interior and in which the joint is at least partly arranged, and a gas-permeable connection which connects the cavity of the rod to the interior of the sealing bellows and comprises at least one groove which is formed in an end face of the joint that faces the rod, opens into the interior and has a radially outer end, the radially outer end of the groove ending set apart, in particular set radially apart, from the outer circumferential contour or outer edge of the end face. The groove is in this case preferably closed at its radially outer end, in particular closed on the end face side and/or in the radial direction.
As the gas-permeable connection to the radially outer end of the groove ends set apart from the outer circumferential contour of the end face or end surface, it is possible to prevent the groove from passing through the outer circumferential
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contour of the end face. Thus, the joint can have a lateral surface or outer circumferential surface which surrounds or encloses the end face or the groove formed in the end face without the groove passing through this lateral surface. This allows the drawbacks and limitations mentioned with regard to the prior art to be avoided. In particular, the gas-permeable connection opens in this case into the interior of the sealing bellows via the radially outer end. The at least one groove can in this case run fully in the end face.
Preferably, the lateral surface is configured as or comprises a key surface having for example a polygonal, in particular square, hexagonal or octagonal circumferential contour or shape. The outer circumferential contour of the end face can lie on the lateral surface or key surface. Furthermore, the at least one groove runs preferably transversely or radially to the longitudinal direction of the rod and can be straight in its formation. The longitudinal direction of the rod coincides in particular with the longitudinal direction of the joint assembly, so that the term "radially" denotes preferably a direction transverse or perpendicular to the longitudinal direction. Furthermore, the term "axially" denotes in particular a direction parallel to the longitudinal direction or a direction coinciding therewith.
The radially outer end of the groove is preferably set radially less far apart from the longitudinal direction than the outer circumferential contour of the end face. As the, in particular radially outer, end of the groove opens into the interior, said end can lie radially outside a lateral surface of the rod or radially outside-the radial extension of the lateral surface of the rod. As the rod rests preferably against the end face, the outer end of the groove is in particular arranged radially outside a contact surface by means of which the rod rests against the end face. The contact surface can be annular in its formation and surround or enclose a radially inner region from which the groove extends for example up to the radially outer end. Furthermore, the groove has preferably a radially inner region or a radially inner end from which the groove extends up to the radially outer end. The radially inner region or the radially inner end of the groove is in particular set less far apart from the longitudinal direction
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than the radially outer end of the groove and lies preferably within the region surrounded by the contact surface or can be enclosed by said contact surface. Furthermore, the radially outer end of the groove is preferably arranged radially between, and in particular set radially apart from, an outer circumferential contour of the contact surface and the outer circumferential contour of the end surface.
The rod can be connected to the joint journal which has the end surface and on which or in which the groove runs. Preferably, the rod is however connected to the joint housing which has the end face and in or on which the groove is formed. In this case, the groove can be provided on or in a base of the joint housing, which base opposes an opening through which the ball journal extends out of the joint housing. The base is in particular formed in one piece with the joint housing. Furthermore, the base preferably has the end face of the joint that faces the rod.
The joint housing has in particular a housing recess which is delimited by a housing wall and in which the joint journal sits. In this case, a bearing shell, which is arranged in the joint housing and in which the ball journal is mounted, can be interposed. Furthermore, a plurality of, for example two or three, grooves, which are in particular similar in their formation but rotated relative to one another about the longitudinal direction, can be provided.
The gas-permeable connection can have at least a second groove which at least indirectly or directly adjoins the (first) groove, runs at least in certain regions or entirely within the rod and opens into the cavity. In this case, the two grooves preferably do not run parallel to each other. In particular, the second groove runs in the direction of or parallel to the longitudinal axis of the rod (axial direction), whereas the first groove can run obliquely or transversely to the longitudinal axis (radial direction). The first and/or the second groove have preferably a straight course. Furthermore, a helical course of the first and/or second groove is possible. The two grooves can merge with each other and in particular form together an L-shaped groove course or an L-shaped groove. The transition between the two
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grooves is formed in particular in the radially inner region or at the radially inner end of the first groove.
The joint has preferably an axial journal which engages with the cavity of the rod. The journal sits in particular on the end face and can be formed in one piece with the joint housing. Preferably, the journal is provided with an outer thread and screwed into the rod which has for this purpose in particular an inner thread which meshes with the outer thread. The journal is preferably connected to the base or formed in one piece therewith.
The second groove can be formed on the inner wall of the rod. However, as the joint housing preferably has the journal which engages with the cavity, the second groove is formed in particular in the lateral surface thereof." The second groove extends in this case for example from an, in particular, free end of the journal that is remote from the joint housing up to the end surface and/or the first groove. If the joint and the rod are screwed together, the second groove runs preferably in, or in the region of, the outer thread of the journal or the inner thread of the rod. Furthermore, a plurality of, for example two or three, (second) grooves, which are in particular similar in their formation but rotated relative to one another about the longitudinal direction, can be provided on the journal and/or on the inner wall of the rod.
Preferably, three radial grooves, which enclose with one another an angle of 120°, are provided in the end face formed on the housing. Furthermore, there can run in the journal three axial grooves which enclose with one another an angle of 120° and adjoin the radial grooves in such a way as to form of the six grooves a total of three L-shaped grooves which enclose with one another an angle of 120° and each merge both with the cavity of the rod and with the interior of the sealing bellows. The radial grooves end with their radially outer ends set apart from the outer circumferential contour of the end surface and in particular do not pass through the outer circumferential contour. Furthermore, a contact surface of the rod can rest on the end face side against the end face of the housing that faces the rod, the radially
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outer ends of the radial grooves lying radially outside the contact surface and being open toward the interior. The radially outer ends of the radial grooves lie in this case in particular radially within the outer circumferential contour of the end surface.
The rod can be connected to a steering gear and be moved, in particular be displaced in the longitudinal direction of the rod, by means of the steering gear. In this case, the rod is preferably configured. as a toothed rack which forms together with the steering gear a rack-and-pinion steering system or a rack-and-pinion steering gear. The sealing bellows can rest so as to produce a seal on the one hand against the steering gear or against a housing of the steering gear and on the other hand against the joint journal or against a coupling member connected thereto.
The joint is preferably a ball joint, so that the joint journal is configured as a ball journal, the ball joint of which is rotatably and pivotably mounted in the joint housing.
The cavity formed within the rod runs in particular in the longitudinal direction of said rod and extends preferably up to the end face of the rod that faces the joint. Within the rod, the cavity can be axially delimited or formed as a blind hole. Alternatively, the cavity can extend through the rod. Furthermore, a plurality of cavities can be provided in the rod. Likewise, it is possible for the rod to be connected to a second joint and to extend between these two joints. In this case, the two joints can be of similar construction.
As the grooves described in the present document are part of or form a gas-permeable connection, they are preferably free grooves.
The invention will be described hereinafter based on a preferred embodiment and with reference to the drawings, in which:
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Fig. 1 is a partial sectional view of a rack-and-pinion steering system;
Fig. 2 is a sectional view of a ball joint for the rack-and-pinion steering system
according to one embodiment of the invention; Fig. 3 is a side view of the ball joint according to Fig. 2 with a partly cut-away
view of a gas-permeable connection; Fig. 4 is a plan view onto the end face of the ball joint that faces the toothed rack
according to Fig. 2; Fig. 5 shows a plurality of groove profiles; Fig. 6 shows a plurality of groove courses; and Fig. 7 shows differing numbers of grooves.
Fig. 1 is a partly sectional view of a rack-and-pinion steering system 1, a toothed rack 4, which is displaceable by means of the steering gear 3 in the direction of and in the opposite direction to the arrow 5, being mounted in a housing 2 of a steering gear 3. The toothed rack 4 has a recess 6 and is connected at one end to a ball joint 7. The ball joint 7 has a joint housing 8 and a ball journal 9 which is rotatably and pivotably mounted in said joint housing and sits with a joint ball 18 (see Fig. 2) in a housing recess 16 (see Fig. 2) which is formed in the joint housing 8 and delimited by a wall 17 (see Fig. 2) of the joint housing 8. In this case, the ball journal 9 extends through an opening 19 provided in the ball joint housing 8 (see Fig. 2) out of said ball joint housing, sealing bellows 10 resting at one end so as to produce a seal against the ball journal 9 outside the ball joint housing 8. At its other end, the sealing bellows 10 rests so as to produce a seal against the housing 2 of the steering gear 3, thus forming between the two ends of the sealing bellows 10 an interior 11 which is delimited by said bellows and in which the ball joint housing 8, an end region of the toothed rack 4 and also a part of the ball journal 9 are arranged. The longitudinal axis of the toothed rack 4 is in this case denoted by reference numeral 12, the arrow 5 running parallel to or in the direction of the longitudinal axis 12.
If the toothed rack 4 is displaced in the opposite direction to the arrow 5 by means of the steering gear 3, the sealing bellows 10 are pressed together or compressed, and
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this can lead to a rise in pressure of the air present in the interior 11 of the sealing bellows 10. If, on the other hand, the toothed rack 4 is displaced in the direction of the arrow 5 by means of the steering gear 3, the sealing bellows 10, which are configured as folding bellows, are stretched or extended, and this can lead to a drop in pressure of the air present in the interior 11 of the sealing bellows 10. To allow such fluctuations in pressure to be compensated for, the rack-and-pinion steering system 1 has a gas-permeable connection 13 (see Fig. 2) which connects the cavity 6 of the toothed rack 4 to the interior 11 of the sealing bellows 10 in an air-permeable manner. It is thus possible for air to be discharged from the interior 11 or for air to be supplied to the interior 11 through the cavity 6. If the cavity 6 does not extend through the toothed rack 4, the air or the compensating gases can be diverted via the housing 2 of the steering gear 3.
Fig. 2 is a sectional view of the ball joint 7 of the rack-and-pinion steering system 1 according to one embodiment of the invention, the cavity 6 being connected in an air-permeable manner via the gas-permeable connection 13 to the interior 11, which is arranged outside the ball joint housing 8, of the sealing bellows 10 (not shown in this figure).
The joint housing 8 has an axial journal 20 which is in particular formed in one piece with said joint housing, and which is provided with an outer thread and engages with the cavity 6 of the toothed rack 4. In this case, an inner thread, which engages with the outer thread of the journal 20, is formed in the region of the end of the toothed rack 4 that faces the ball joint 7, on the inner wall of said toothed rack. Thus, the ball joint housing 8 and the toothed rack 4 are screwed together. Furthermore, the ball joint housing 8 has an end face 21 which faces the toothed rack 4 and annularly surrounds the journal 20 and against which the toothed rack 4 rests on the end face side.
The gas-permeable connection 13 has at least one groove 14 formed on the lateral surface of the journal 20 and at least one groove 15 which is formed in the end face
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21 and merges at the housing-side end of the journal 20 with the groove 14 to which it is connected in an air-permeable manner. In this case, the, in particular axially running, groove 14 extends preferably from the end face 21 of the joint housing 8 up to an end face of the journal 20 that is remote from the joint housing 8, and opens into the recess 6. Furthermore, the groove 14 runs at least in certain portions in, or in the region of, the outer thread of the journal 20. The at least one groove 15, which runs in the end face 21, extends radially from the journal 20 outward and opens, in a radially outer end region 27 (see Fig. 3), into the interior 11 of the sealing bellows 10 (not shown in this figure). In this case, however, the groove 15 does not extend up to the outer circumferential contour 28 (see Fig. 4) of the end surface 21 but rather is set apart therefrom by a distance 29 (see Fig. 4).
The outer circumferential contour 28 is part of a polygonal key surface 22 which is formed on the lateral surface of the ball joint housing 8 and extends in the axial direction only over a part of the lateral surface of the ball joint housing 8. The key surface 22 surrounds or encloses the groove or grooves 15 without said grooves passing through the key surface 22.
Fig. 3 is a partial side view of the ball joint housing 8 from which the toothed rack 4 has been omitted, producing an L-shaped course of the grooves 14 and 15 which merge with each other, which course is shown partly in section. The groove 15 encloses in this case a right angle with the groove 14.
Fig. 4 is a plan view onto the end face 21 of the ball joint housing 8 from which the toothed rack 4 has been omitted, clearly showing that, according to the embodiment, there are provided three radial grooves 15 in the end face 21 and three axial grooves 14 on the journal 20. In this case, these six grooves 14 and 15 together form three L-shaped grooves, of which each pair of adjacent grooves encloses an angle of 120°.
The groove or the grooves 15 run in particular in the radial direction and can have one of the groove profile shapes 23, 24, 25 or 26 which may be seen from Fig. 5
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and/or one of the groove courses which may be seen from Fig. 6. In particular, it may be seen from Fig. 6 that the groove 15 can, according to a modification of the embodiment, run helically. Alternatively, the groove runs or the grooves 15 run straight. Furthermore, Fig. 7 shows that a different number of grooves 15 can be provided. In addition, if a further few different groove courses may be seen from Fig. 7.
For the groove or grooves 14 provided on the journal 20, the groove profile shapes, groove courses and/or numbers of grooves which may be seen from Fig. 5, 6 and 7 are in this case accordingly possible. Furthermore, the groove 14 can be configured as a helical groove on the threaded journal 20.
Although not shown, it is possible in all embodiments for a bearing shell 30, in which the joint ball 18 is mounted, to be arranged within the recess 16 between the joint ball 18 and the housing wall 17.
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List of reference numerals
1 Rack-and-pinion steering system/joint assembly
2 Housing of the steering gear
3 Steering gear
4 Toothed rack
5 Arrow
6 Recess in the toothed rack/cavity
7 Ball joint
8 Ball joint housing
9 Ball journal
10 Sealing bellows
11 Interior of the sealing bellows
12 Longitudinal axis of the toothed rack
13 Air-permeable connection
14 Axial groove
15 Radial groove
16 Recess in housing
17 Housing wall
18 Joint ball
19 Opening in ball joint housing
20 Journal on joint housing
21 End surface
22 Key surface
23 Groove profile
24 Groove profile
25 Groove profile
26 Groove profile
27 Outer end of the radial groove
28 Outer circumferential contour of the end surface
29 Distance between outer groove end and outer circumferential contour of the end surface
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WE CLAIM:
1. Joint assembly for a vehicle, with a joint (7) having a joint housing (8) and a
joint journal (9) which is mounted so as to be able to move relative to said
joint housing, a rod (4) which has a cavity (6) and is connected to the joint (7),
sealing bellows (10) which delimit an interior (11) and in which the joint (7) is
at least partly arranged, and a gas-permeable connection (13) which connects
the cavity (6) of the rod (4) to the interior (11) of the sealing bellows (10) and
has at least one groove (15) which is formed in an end face (21) of the joint (7)
that faces the rod (4), opens into the interior (11) and has a radially outer end
(27), characterised in that
- the radially outer end (27) of the groove (15) ends set apart from an outer circumferential contour (28) of the end surface (21).
2. Joint assembly according to claim 1, characterised in that the radially outer end (27) of the groove (15) opens into the interior (11).
3. Joint assembly according to either claim 1 or claim. 2, characterised in that the joint (7) has a key surface (21) which encloses the groove (15) formed in the end face (21).
4. Joint assembly according to any one of the preceding claims, characterised in that the radially outer end (27) of the groove (15) lies radially outside a contact surface by means of which the rod (4) rests against the end face (21).
5. Joint assembly according to claim 4, characterised in that the contact surface is annular in its formation and surrounds a radially inner region from which the groove (15) extends up to the radially outer end (27).
6. Joint assembly according to any one of the preceding claims, characterised in that the gas-permeable connection (13) has at least a second groove (14) which
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at least indirectly adjoins the groove (15), runs at least in certain regions within the rod (4) and opens into the cavity (6) of the rod (4).
7. Joint assembly according to claim 6, characterised in that the two grooves (14, 15) run transversely to each other and the second groove (14) runs in the direction of or parallel to the longitudinal axis (12) of the rod (4).
8. Joint assembly according to either claim 6 or claim 7, characterised in that there is arranged at the end surface (21) a journal (20) which engages with the cavity (6) and in the lateral surface of which the second groove (14) runs.
9. Joint assembly according to any one of the preceding claims, characterised in that the joint housing (8) is connected to the rod (4) and has a housing recess (16) which is delimited by a housing wall (17) and in which the joint journal
(9) sits, the end surface (21) being provided on the joint housing (8) and being
remote from or opposing an opening (19) through which the joint journal (9)
extends out of the joint housing (8).
10. Joint assembly according to any one of the preceding claims, characterised in that the rod (4) is connected to a steering gear (3) and can be moved by means of the steering gear (3).
11. Joint assembly according to claim 10, characterised in that the sealing bellows
(10) rest so as to produce a seal on the one hand against the steering gear (3)
or against a housing (2) of the steering gear (3) and on the other hand against
the joint journal (9) or against a coupling member connected thereto.
12. Joint assembly according to any one of the preceding claims, characterised in
that the rod (4) is a toothed rack.
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13. Joint assembly according to any one of the preceding claims, characterised in that the joint (7) is a ball joint and the joint journal (9) is a ball journal, the joint ball (18) of which is rotatably and pivotably mounted in the joint housing (8).
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Dated this 25th day of August, 2008