WO2011028155A1

WO2011028155A1 - Steering link rod for a vehicle and vehicle with a steering link rod

Info

Publication number: WO2011028155A1
Application number: PCT/SE2009/000401
Authority: WO
Inventors: Leon Fuks; Jan-Olof Bodin
Original assignee: Volvo Lastvagnar Ab
Priority date: 2009-09-04
Filing date: 2009-09-04
Publication date: 2011-03-10

Abstract

The invention relates to a steering link rod (20) for connecting to a steering knuckle (18) of a vehicle (10) and to a corresponding vehicle using such a steering link rod (20). The steering rod comprises a massive body (26) with a longitudinal extension (L) between a first end portion (22) and a second end portion (24).

Description

- -

D E S C R I P T I O N Steering Link Rod for a Vehicle and Vehicle with a Steering Link Rod

TECHNICAL FIELD

The invention relates to a steering link rod for connecting to a steering knuckle of a vehicle and a vehicle with a steering link rod. Particularly, the invention is applicable to heavy vehicles, in particular trucks. The invention is, however, not restricted to trucks, but may also be used in buses or work machines, such as wheel loaders, articulated haulers, excavators and the like.

BACKGROUND OF THE INVENTION

Different types of rods used in vehicles, such as steering link rods and track rods, require that the length of the rod can be adjusted in order to enable the rod to be mounted and/or a certain alignment operation to be carried out. The steering link rod connecting the drop arm and the steering arm to each other is usually provided with ball joints at both ends. In order to adjust the length of the steering link rod when being mounted, the link is also provided with left and right hand screw threads. This prior art solution is using a bended tube with an attachment unit for the ball joints at both ends. The screw threads at both ends are used to attach the ball joints to the tube and to adjust the length of the steering link rod. A pipe clamp may be used to secure the adjusted length of the steering link rod. The adjustment mechanism of a drag link which has been used under unfavourable ambient conditions and/or for a long time can stop working due to dirt and corrosion. This in turn implies that when accomplishing a wheel alignment of a truck, the steering link rod has often to be replaced by a new steering link rod which is able to be adjusted as desired. Additionally, the bended tube is not an ideal shape in view of stiffness and buckling load during working conditions.

SUMMARY OF THE INVENTION - -

An object of the invention is to provide a steering link rod for connecting to a steering knuckle of a vehicle where stiffness and/or buckling load can be optimized compared to prior art rods.

Another object is to provide a vehicle with such a link rod.

The objects are achieved by the features according to the independent claims. The other claims and the description disclose advantageous embodiments of the invention.

A steering link rod is proposed for connecting to a steering knuckle of a vehicle which comprises a massive body with a longitudinal extension between a first end portion and a second end portion.

By providing such a steering link rod the stiffness and/or buckling load can be optimized especially at the bending regions of the steering link rod. Other than a hollow body, the massive body can be treated in a way to adapt elastic and mechanical properties of the link rod all over its length, particularly if the body comprises one or more bends. The invention favourably supports an improved use of a corresponding packaging space in the vehicle since the massive body between the end portions can be adapted to the available packaging space. As an additional advantage only few parts are required to build the steering link rod according to the invention.

According to a favourable embodiment of the invention, the body of the steering link rod can be at least partially forged, cast or welded. These forming procedures make it possible to achieve a desired material distribution to form a desired shape for the body. Expediently, by forging the steering link rod can be manufactured in a cost efficient way.

According to another favourable embodiment of the invention, the material distribution along the longitudinal extension of the body and/or along a direction crosswise to the longitudinal extension can be adjusted according to a desired - - stiffness and/or buckling load of the body. This allows to increase the stiffness and/or the buckling load of the body where it is required especially at bending regions and to decrease the stiffness and/or the buckling load where it is possible especially at the end portions of the body. As a result, the material thickness can be optimized and the weight of the steering link rod can be reduced according to the conditions of use. Additionally, the lifetime of the steering link rod can be extended.

According to another favourable embodiment of the invention, the material thickness in at least one end portion of the body can be smaller than in a middle portion of the body. This also provides an optimization in material thickness which can be easily adapted to the requirements of the intended use so that the weight of the steering link rod can be reduced. According to another favourable embodiment of the invention, the material thickness along the direction crosswise to the longitudinal extension can be smaller at a centre portion than in an outer portion. Likewise as mentioned above, this also provides an optimization in material thickness which can be easily adapted to the requirements of the intended use so that the weight of the steering link rod can be reduced.

According to another favourable embodiment of the invention, at least one end portion of the rod can comprise a bearing sleeve for a ball joint having a ball and a pin. By such means the coupling of the steering link rod to a further component can be accomplished in an easy and effective way.

According to another favourable embodiment of the invention, the bearing sleeve can be integral with the body. As a result, the number of parts and the number of steps during the production procedure can be further reduced. Reproducibility of manufacture of the link rod the can be improved.

According to another favourable embodiment of the invention, the bearing sleeve can be attached to the body. As a result, the steering link rod can be easily adapted to be connected to components with different sizes according to the - - requirements in the vehicle where the link rod has to be installed. The same body can be used with different bearing sleeves in different designs.

According to another favourable embodiment of the invention, at least one end portion of the rod can comprise a bearing sleeve in which a length adjustment device is arranged. Expediently, the overall length of the steering link rod can be kept constant and an effective length of the steering link rod can be adjusted by the length adjustment device in a way such that the adjustment mechanism is less sensitive to dirt and corrosion so the life of the length adjustment function of the steering link rod can be increased. The length adjustment device can be an eccentric adjustment device, for example, which allows easy adjustment.

According to another favourable embodiment of the invention, the length

adjustment device can comprise a pivot member in which the ball of the ball joint is arranged which pivot member is pivotally adjustable relative to the bearing sleeve and a axis of the ball joint is arranged offset relative to a centre axis of the pivot member so as to enable adjustment of the effective length of the steering link rod by pivoting the pivot member. The arrangement is compact and allows a

comfortable length adjustment.

By introduction of the eccentric function, screw threads for adjustment of the length of the steering link rod can be eliminated, and thereby the strength of the massive body can also be increased. For example, in some applications the massive body is bent such that the main longitudinal extension direction of the rod in a first portion thereof is different from the main longitudinal extension direction of the rod in a second portion thereof. By way of example, due to the limited space the drag link is often bent. This in turn makes the drag link weaker with respect to buckling. Elimination of the screw threads implies that the material thickness of the massive body can be used more efficiently in order to obtain the requisite strength of the steering link rod.

According to another favourable embodiment of the invention, the pivot member can comprise a sleeve member for the ball joint with a groove in which a thread is brought in, wherein the pivot member is pivoted by rotating a screw which screw - - acts on the thread in the groove. By such a means the adjustment of the effective length of the steering link rod can be accomplished in an easy and effective way. Advantageously, the pivot member can be continuously pivoted relative to the bearing sleeve. Hereby the steering link rod length can be adjusted when the rod is already connected to a further component at one or both ends of the rod, which can facilitate the assembling procedure.

According to another favourable embodiment of the invention, the at least one end portion can comprise a mechanism for locking the pivot member against pivoting relative to the bearing sleeve. By such a mechanism the steering link rod can be adjusted to the desired length when the locking mechanism is not activated, and the locking mechanism can be activated subsequently to lock the pivot member and maintain a constant effective length of the steering rod after adjustment thereof.

According to another favourable embodiment of the invention, the at least one end portion can comprise a built-in safety stop means. By such a means the

adjustment region can be accomplished in an easy and effective way. Damage to the length adjustment device due to overwinding the thread can be avoided. The length of the link rod can be adjusted in a reproducible way.

According to another aspect of the invention, a vehicle is proposed, especially to a heavy vehicle, in particular to a truck comprising a steering link rod for connecting to a steering knuckle of a vehicle which comprises a massive body with a longitudinal extension between a first end portion and a second end portion.

Production costs can be reduced and an improved stability of the link rod can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiment(s), but not restricted to the embodiments, wherein is shown schematically: - -

Fig. 1 a perspective view of a front portion of truck having a steering link rod according to the invention;

Fig. 2 a perspective view of an example embodiment of a steering link rod; Fig. 3 a cross sectional view of a steering link rod along the line III - III in

Fig. 2;

Fig. 4 a bottom view of an example embodiment of a pivoting member for the steering link rod shown in Fig. 2 or 3;

Fig. 5 a perspective view of the pivoting member shown in Fig. 4;

Fig. 6 more detailed illustrations of a first end portion of the steering rod according to the invention with the bearing sleeve shown in Fig. 4 or

5;

Fig. 7a-c adjustment of different lengths of the steering rod in Fig. 4 or 5 by pivoting the pivot member;

Fig. 8 a perspective view of an example embodiment of a steering link rod according to the invention with bearing sleeves; and

Fig. 9 schematic illustrations of steering link rods according to the invention with different effective lengths.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the drawings, equal or similar elements are referred to by equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention. Fig. 1 is a perspective view of a front portion of a heavy vehicle 10, embodied by way of example as a truck, provided with a steering link rod 20 according to the invention connected to a front axle 16 of the vehicle 10. In this example

embodiment the steering link rod 20 is a drag link which connects a drop arm 12 - - and a steering arm 14 of the vehicle 10. The steering arm 14 is coupled to a steering knuckle 18 of the front axle 16.

The steering link rod 20 comprises a massive body 26, a first ball joint 34 arranged at a first end 22 of the steering link rod 20 for coupling the rod 20 to a further component, which further component is the steering arm 14 in the example embodiment illustrated in Fig. 1 , and a second ball joint 34b arranged at a second end 24 of the steering link rod 20 for coupling the rod 20 to a further component, which further component is the drop arm 12 in the example embodiment illustrated in Fig. 1.

In Figs. 2 and 3 an example of a steering link rod 20 according to the invention is illustrated. The steering link rod 20 comprises a massive body 26 with a

longitudinal extension L of a fixed length between a first end portion 22 and a second end portion 24 wherein the stiffness and/or the buckling load are optimized especially at the bending regions of the steering link rod 20. The massive body 26 of the steering rod 20 is designed in order to allow the material thickness of the rod member to be used more efficiently in order to obtain the requisite strength of the steering link rod 20. The massive body 26 of the steering link rod 20 can for example be formed in one piece. In the embodiment shown, the steering link rod 20 is designed with the massive body 26 being bent such that a first main longitudinal extension direction 26.6 of the body 26 in a first portion 26.2 thereof is different from a second main longitudinal extension direction 26.7 of the body 26 in a second portion 26.3 thereof and is different from a third main longitudinal extension direction 26.8 of the body 26 in a third portion 26.4 thereof. To achieve a desired material distribution to form the desired shape the massive body 26 of the steering link rod 20 can be at least partially forged, cast or welded. The material distribution along the longitudinal extension L of the body 26 and/or along a direction B oriented crosswise to the longitudinal extension L is adjusted according to a desired stiffness and/or buckling load of the body 26. This makes it possible to increase the stiffness and/or the buckling load of the body 26 where it is required especially at bending regions and to decrease the stiffness and/or the buckling load where it is possible especially at the end portions 26.1 , 26.5 of the body 26. In the embodiment the material thickness C in both end portions 26.1 , 26.5 of the - - body 26 are smaller than in the middle portions 26.2, 26.3, 26.4 of the body 26. In the embodiment the material thickness along the direction B crosswise to the longitudinal extension L is smaller at a centre portion 28 than in outer portions 30. The described material thickness distribution along the body 26 allows for an optimization of the shape and weight of the steering link rod 20. The first end 22 of the steering link rod 20 comprises a first bearing sleeve 22.1 with an inner surface 22.2 and the second end 24 of the steering link rod 20 comprises a second bearing sleeve 24.1 with an inner surface 24.2. The first bearing sleeve 22.1 is used to carry the first ball joint 34 and the second bearing sleeve 24.1 is used to carry the second ball joint 34b.

As illustrated in Figs. 4 and 5, the first ball joint 34 comprises a ball 42 and a pin 38 and is arranged in a pivot member 32 of a length adjustment device 54. The pin 38 of the first ball joint 34 may have a longitudinal extension direction which is substantially in parallel with a centre axis 48.2 of the pivot member 32. The ball 42 is arranged in the pivot member 32 which pivot member can comprise a sleeve member 36 for example, although the pivot member 32 may be designed in many different ways within the scope of the invention. By way of example, the pivot member 32 comprises a sleeve member 36 for the ball joint 34 which is provided with an outer periphery 40 in which a groove 44 with a thread is brought in. An axis

48.1 of the ball joint 34 is arranged offset (distance D) relative to the centre axis

48.2 of the sleeve member 36 and therefore of the pivot member 32. The pin 38 is preferably provided with a conical portion 38.1 and threads (not shown) in order to interconnect the steering link rod 20 with a further component. The ball 42 and the pin 38 are preferably aligned relative to each other along the same axis 48.1.

Other basic features of the ball joint 34 with respect to for example any socket in which the ball 42 is arranged (which socket in turn is arranged in the pivot member 32) and how the ball joint 34 is sealed, etc., are well known to the skilled person to which conventional ball joints are known. Consequently, these components and features are not further discussed herein. By way of example, a collar 46 is used to seal the ball joint 34.

The steering link rods illustrated in Figs. 6 to 9 have a ball joint 34, 34b at each end 22, 24. The pivot member 32 with the first ball joint 34 shown in Fig. 4 and 5 - - can be used in one or both bearing sleeves 22.1 , 24.1 of the steering link rod 20 to enable adjustment of the effective length L1 , L2, L3 of the steering link rod 20 as described herein. If only one such pivot member 32 is used, any other connection means, as for example a conventional ball joint 34b as illustrated, can be used at the other end portion 24 of the steering link rod 20. To adjust the effective length of the steering link rod 20 the first ball joint 34 is arranged in the pivot member 32 shown in Fig. 4 and 5 which is arranged in the first bearing sleeve 22.1 and the pivot member 32 and thereby the first ball joint 34 is pivotally adjustable relative to the first bearing sleeve 22.1. The pivot member 32 is preferably mounted to be continuously pivoted relative to the first bearing sleeve 22.1 to the desired pivot position.

Referring now to Fig. 6 and 7, by pivoting the pivot member 32 and thereby pivoting the first ball joint 34 relative to the first bearing sleeve 22.1 the effective length L1 , L2, L3 of the steering link rod 20 can be adjusted. Thus, the "effective" length L1 , L2, L3 is the distance between the both connection positions situated at each end portion 22, 24 of the steering link rod 20. The connection positions are the positions where the steering link rod 20 is to be interconnected with other components. In other words; the distance between the connection positions can be varied by pivoting the pivot member 32 although the total length L of the steering link rod 20 is not changed.

In Fig. 7a to 7c three different pivot positions of the pivot member 32 are

schematically shown and the effective length of the steering link rod 20 is denoted L1 , L2 and L3, respectively, in the current positions, wherein L1 is representing the shortest and L3 is representing the longest possible effective length of the steering link rod 20. The total length of the steering link rod 20 is kept constant and is denoted L. In the example embodiment illustrated in Figs. 6 to 9 the sleeve member 36 is pivotally arranged in the first bearing sleeve 22.1 , and the sleeve member 36 can be continuously pivoted relative to the first bearing sleeve 22.1. To enable the first ball joint 34 to be fixed in the desired position after adjustment of the effective length of the steering link rod 20, the steering link rod 20 preferably comprises a mechanism 52 shown in Figs. 8 and 9 for locking the pivot member 32 against pivoting relative to the first bearing sleeve 22.1. Such a locking mechanism 52 can be based on increased friction between the pivot member 32 and the first bearing sleeve 22.1 when the locking mechanism 52 is activated.

For example as illustrated in Figs. 8 and 9, the locking mechanism 52 can be arranged to lock the pivot member 32 by clamping the pivot member 32 between two portions 22.3, 22.4 of the first end portion 22 of the steering link rod 20. The pivot member 32 is pivotally arranged in the first bearing sleeve 22.1 by the fact that the outer periphery 40 of the sleeve member 36 can slide relative to an inner surface 22.2 of the first bearing sleeve 22.1. The pivot member 32 can be a circular component, and the first bearing sleeve 22.1 can have a corresponding circular aperture for accommodating the pivot member 32 inside the first bearing sleeve 22.1.

In the example embodiment illustrated in Figs. 8 and 9, the steering link rod 20 has a slit 22.5 which extends on to the aperture for accommodating the first bearing sleeve 22.1. The slit 22.5 preferably extends substantially in parallel with the longitudinal extension direction of the steering link rod 20. A screw or bolt 50 is arranged in the first end portion 26.1 of the steering link rod 20 in order to clamp the pivot member 32 between the two portions 22.3, 22.4 of the first end portion 26.1 of the steering link rod 20. By means of the slit 22.5 and the screw 50 with a lock nut 50.3 the size of the aperture can be varied so as to clamp the pivot member 32 and increase the friction between the first bearing sleeve 22.1 and the pivot member 32. The screw or bolt 50 is preferably arranged substantially perpendicular relative to the slit 22.5 in the first end portion 26.1 of the steering link rod 20, and when tightening the screw or bolt 50 the slit 22.5 by rotating the lock nut 50.3 the width of the slit 22.5 is decreased and the first end portion 26.1 is clamped around the pivot member 32. The screw or bolt 50 comprises a head 50.1 for receiving an adjustment tool (not shown) for pivoting the pivot member 32 and a thread 50.2 interacting with the thread of the groove 44 in the sleeve member 36 when the screw 50 is rotated. The effective length of the steering link rod 20 is adjusted by releasing and unscrewing the locknut 50.3 until a stop ring 50.4 and then rotating the screw 50 so that the sleeve member 36 is pivoted in respect to the first bearing sleeve 22.1. The sleeve member 36 can be mounted in the first bearing sleeve 22.1 as previously described herein, and then the sleeve member 36 can be pivoted to the desired position, and finally the locknut 50.3 can be tightened to lock the sleeve member 36 against pivoting relative the first bearing sleeve 22.1. The thread does cover only a part of the groove 44 which is required to pivot the sleeve member 36. The first bearing sleeve 22.1 can be provided with a first stop means 22.6 for preventing the pivoting of the pivot member 32 relative to the first bearing sleeve 22.1 in a first direction when the thread of the groove 44 is reaching the stop means 22.6. A second stop means (not shown) is preventing the pivoting of the pivot member 32 relative to the first bearing sleeve 22.1 in a second direction when the thread of the groove 44 is reaching the stop means 22.6. Favourably, such stop means 22.6 are integral with the first bearing sleeve 22.1. The stop means 22.6 could be a flange extending in the groove 44 of the aperture in the sleeve member 36. Such a flange can be provided by machining the first bearing sleeve 22.1 or by forging the material to the desired shape.

Embodiments of the invention favourably support the ideal use of a corresponding packaging space in the vehicle since the massive body between the end portions can be adapted to the available packaging space and stiffness and/or buckling load of the steering link rod can be optimized by adapting the material thickness according to the conditions of use and the weight of the steering link rod can be reduced.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

C L A I M S

1. A steering link rod (20) for connecting to a steering knuckle (18) of a vehicle (10), characterized by a massive body (26) with a longitudinal extension (L) between a first end portion (22) and a second end portion (24).

2. The steering link rod according to claim 1 , characterized in that the body (26) is at least partially forged, cast or welded.

3. The steering link rod according to claim 1 or 2, characterized in that a

material distribution along the longitudinal extension (L) of the body (26) and/or along a direction (B) crosswise to the longitudinal extension (L) is adjusted according to a desired stiffness of the body (26).

4. The steering link rod according to any preceding claim, characterized in that a material thickness (C) in at least one end portion (26.1 , 26.5) of the body (26) is smaller than in a middle portion (26.2, 26.3, 26.4) of the body (26).

5. The steering link rod according to any preceding claim, characterized in that a material thickness along the direction (B) crosswise to the longitudinal extension (L) is smaller at a centre portion (28) than in an outer portion (30).

6. The steering link rod according to any preceding claim, characterized in that at least one end portion (22, 24) of the rod (20) comprises a bearing sleeve (22.1 , 24.1) for a ball joint (34) having a ball (42) and a pin (38).

7. The steering link rod according to claim 6, characterized in that the bearing sleeve (22.1 , 24.1) is integral with the body (26).

8. The steering link rod according to claim 6, characterized in that the bearing sleeve (22.1 , 24.1) is attached to the body (26).

9. The steering link rod according to any preceding claim, characterized in that at least one end portion (22) of the rod (20) comprises a bearing sleeve (22.1) in which a length adjustment device (54) is arranged.

10. The steering link rod according to claim 9, characterized in that the length adjustment device (54) is an eccentric adjustment device.

11.The steering link rod according to claim 9 or 10, characterized in that the length adjustment device (54) comprises a pivot member (32) in which the ball (42) of the ball joint (34) is arranged, which pivot member (32) is pivotally adjustable relative to the bearing sleeve (22.1) and a axis (48.1) of the ball joint (34) is arranged offset relative to a centre axis (48.2) of the pivot member (32) so as to enable adjustment of the effective length (L1 , L2, L3) of the steering link rod (20) by pivoting the pivot member (32). 2. The steering link rod according to anyone of the claims 9 to 1 ,

characterized in that the pivot member (32) comprises a sleeve member (36) for the ball joint (34) with a groove (44) in which a thread is brought in, wherein the pivot member (32) is pivoted by rotating a screw (50) which screw (50) acts on the thread in the groove (44).

13. The steering link rod according to anyone of the claims 9 to 12,

characterized in that the at least one end portion (22) comprises a

mechanism (50.3) for locking the pivot member (32) against pivoting relative to the bearing sleeve (22.1).

14. The steering link rod according to anyone of the claims 9 to 13, characterized in that the at least one end portion (22) comprises a build in safety stop means (22.6).

15. A vehicle (10) comprising a steering link rod (20) according to any

preceding claim.

16. A steering link rod for connecting to a steering knuckle of a vehicle, characterized by a massive body with a longitudinal extension between a first end portion and a second end portion.

17. The steering link rod according to claim 16, characterized in that the body is at least partially forged, cast or welded. 8. The steering link rod according to claim 16 or 17, characterized in that a material distribution along the longitudinal extension of the body and/or along a direction crosswise to the longitudinal extension is adjusted according to a desired stiffness of the body.

19. The steering link rod according to claim16, characterized in that a material thickness in at least one end portion of the body is smaller than in a middle portion of the body.

20. The steering link rod according to claim 16, characterized in that a material thickness along the direction crosswise to the longitudinal extension is smaller at a centre portion than in an outer portion.

21. The steering link rod according to claim16, characterized in that at least one end portion of the rod comprises a bearing sleeve for a ball joint having a ball and a pin.

22. The steering link rod according to claim 21 , characterized in that the

bearing sleeve is integral with the body.

23. The steering link rod according to claim 21 , characterized in that the

bearing sleeve is attached to the body.

24. The steering link rod according to claim 16, characterized in that at least one end portion of the rod comprises a bearing sleeve in which a length adjustment device is arranged.

25. The steering link rod according to claim 24, characterized in that the length adjustment device is an eccentric adjustment device.

26. The steering link rod according to claim 24 or 25, characterized in that the length adjustment device comprises a pivot member in which the ball of the ball joint is arranged, which pivot member is pivotally adjustable relative to the bearing sleeve and a axis of the ball joint is arranged offset relative to a centre axis of the pivot member so as to enable adjustment of the effective length of the steering link rod by pivoting the pivot member.

27. The steering link rod according to claim 24, characterized in that the pivot member comprises a sleeve member for the ball joint with a groove in which a thread is brought in, wherein the pivot member is pivoted by rotating a screw which screw acts on the thread in the groove.

28. The steering link rod according to claim 24, characterized in that the at least one end portion comprises a mechanism for locking the pivot member against pivoting relative to the bearing sleeve. 29. The steering link rod according to claim 24, characterized in that the at least one end portion comprises a build in safety stop means.

30. A vehicle comprising a steering link rod according to claim 16.