WO2014120069A1

WO2014120069A1 - Steering spindle arrangement

Info

Publication number: WO2014120069A1
Application number: PCT/SE2014/050105
Authority: WO
Inventors: Martin STJERNLING
Original assignee: Scania Cv Ab
Priority date: 2013-01-31
Filing date: 2014-01-28
Publication date: 2014-08-07
Also published as: DE112014000375T5; SE536871C2; SE1350109A1

Abstract

The present invention concerns a steering spindle arrangement that comprises a spindle bolt (2), an axle beam (1) that is attached at a central part (2b) of the spindle bolt (2) and a stub axle (3) that comprises a first penetrating hole (5) with a first bearing (8) for the reception of a first part (2a) of the spindle bolt (2), and a second penetrating hole (7) with a second bearing (13) for the reception of a second part (2c) of the spindle bolt (2). The steering spindle arrangement comprises also a first component (22) that is connected in a manner that does not allow it to rotate to the stub axle (3), a second component (23) that is connected in a manner that does not allow it to rotate to the spindle bolt (2), whereby the said components (22, 23) are in contact with each other at a contact area such that different resistances to rotation between the components (22, 23) are created at at least two angles of rotation between the stub axle (3) and the spindle bolt (2).

Description

STEERING SPINDLE ARRANGEMENT

BACKGROUND AND PRIOR ART

The present invention relates to a steering spindle arrangement according to the preamble to claim 1.

A steering spindle arrangement for a steerable wheel in a vehicle generally comprises a spindle bolt that has a conical part for the attachment of an axle beam. A stub axle that supports the wheel is mounted to pivot on the steering spindle bolt with the aid of an upper bearing that may be a sliding bearing and a lower bearing that may be a conical roller bearing. The lower bearing in this case absorbs both axial and radial forces, while the upper bearing absorbs radial forces. The coefficient of friction of glide bearings, however, is not negligible. This results in the sliding bearing experiencing a varying resistance to rotation when the stub axle is pivoted relative to the axle beam, depending on the load on the sliding bearing. For a truck, in particular, the load at a steering spindle arrangement can differ considerably between operating conditions in which the vehicle is loaded and not loaded.

Steerable vehicle wheels that are arranged on a pivotable stub axle experience a resistance to rotation when they are rotated relative to a spindle bolt and an axle beam in a steering spindle arrangement. If the resistance to rotation is too low, there is a risk that vibration arises in the transmission that transfers steering motions from the steering wheel of the vehicle to the steerable wheels. If the resistance to rotation is too high, an unnecessarily large force is required to turn the wheels. It is, therefore, important that the stub axle experiences a resistance to rotation that has a suitable magnitude when it is rotated around the spindle bolt. It is desirable also that the resistance to rotation does not vary with the load at the stub axle.

WO 97/13674 reveals a spindle bolt that is provided with threaded parts at both an upper end and at a lower end. An upper nut is mounted at the upper threaded part and a lower nut is mounted at the lower threaded part. An inner ring on an upper conical roller bearing can be locked against a surface of the axle beam with the aid of the upper nut. The upper conical roller bearing and a lower conical roller bearing can be pre-tensioned by means of the lower nut. Roller bearings are used in this case as bearings for the stub axle at the two ends of the spindle bolt. SUMMARY OF THE INVENTION

The object of the present invention is to provide a steering spindle arrangement where it is possible to vary the resistance to rotation for a stub axle when it is rotated around a spindle bolt, depending on the angle of rotation of the stub axle relative to the spindle bolt and the axle beam.

This object is achieved with a steering spindle arrangement of the type described in the introduction that is characterised by the distinctive features that are specified in the characterising part of claim 1. When a vehicle turns, steerable wheels and stub axles rotate relative to the spindle bolt and the axle beam. In order to obtain optimal driving properties of a vehicle, it is appropriate to vary the resistance to rotation for the steerable wheels depending on the displacement of the steerable wheels. It may be, for example, appropriate to increase the resistance to rotation gradually as the steerable wheels are turned more away from their initial positions, as the vehicle is driven directly forwards. According to the invention, a first component is used that is connected to the stub axle in a manner that does not allow it to rotate, and a second component that is connected to the spindle bolt in a manner that does not allow it to rotate. The said components have a design such that they create a resistance to rotation when the stub axle is rotated relative to the spindle bolt. A varying resistance to rotation can be created when the stub axle is rotated to different angles of rotation relative to the spindle bolt and the axle beam with a suitable design of the said components. It is here possible to obtain a desired resistance to rotation for each individual angle of rotation between the stub axle and the spindle bolt. According to one embodiment of the present invention one of the said components comprises an extended contact path and that the second component comprises at least one contact surface that is adapted to move in contact with the extended contact path when the stub axle takes up different angles of rotation relative to the spindle bolt. It is here possible to design the said components such that the contact surface exerts a varying pressure along different parts of the extended contact path. A desired resistance to rotation can be obtained at different angles of rotation with a suitable variation of the pressure and thus also the friction between the contact surface and the contact path.

According to one embodiment of the present invention, the contact surface is pressed by a spring force against the contact path and that the resistance to rotation is related to the spring force with which the contact surface is pressed against the contact path at different angles of rotation. The magnitude of the spring force here determines the resistance to rotation that is obtained at different angles of rotation. The contact surface can be pressed against the contact path with a spring force in at least one radial direction relative to a central longitudinal axis of the spindle bolt. The contact surface can here exert a pressure that is directed radially outwards against the contact path, or with a pressure that is directed radially inwards against the contact path.

According to one embodiment of the present invention, the component that comprises the extended contact path is constituted by a ring-shaped sheath and that the contact path is constituted by an internal edge surface at the sheath. Such a component has a relatively simple design and it can be made quite small. Thus it requires a small space in a steering spindle arrangement. The sheath may have an external edge surface that is adapted to be brought into contact with an internal surface that defines the penetrating hole at the first arm. The internal and external edge surfaces of the sheath obtain in this way a stable position of attachment in the steering spindle arrangement.

According to one embodiment of the present invention, the steering spindle

arrangement comprises a locking pin, an indentation that comprises a first part at the stub axle and a second part at the primary component, whereby the locking pin is adapted to be applied in the said indentation in order to create the said connection between the stub axle and the first component. With such a design, a rigid coupling can be created between the stub axle and the first component with relatively simple means that require essentially no extra space in the steering spindle arrangement.

According to one embodiment of the present invention, the said component that comprises the contact surface comprises a spring-loaded part is connected to the contact surface, and a central opening such that the component can be applied around the spindle bolt. The contact surface may in this case come into contact with an extended contact path that extends around the spindle bolt at a varying distance from a longitudinal central axis through the spindle bolt. It is an advantage that the component comprise two or more parts that protrude radially outwards with component parts that are connected to peripherally arranged contact surfaces. Since several contact surfaces that are symmetrically arranged around the contact path are used, a stable construction is obtained. A component that comprises a central opening can be easily mounted at the spindle bolt. It is here an advantage if the opening has a magnitude that

corresponds to that of the spindle bolt. The spindle bolt in this way prevents the component being displaced in a radial direction.

According to one embodiment of the present invention, the steering spindle arrangement comprises a locking pin, an indentation that comprises a first part at the spindle bolt and a second part at the second component, whereby the locking pin is adapted to be applied in the said indentation and to create the said connection that does not allow rotation between the stub axle and the secondary component. With such a design, a rigid connection can be created between the second component and the spindle bolt with relatively simple means that require essentially no extra space in the steering spindle arrangement.

According to one embodiment of the present invention, the said bearings are constituted by roller bearings. In contrast to sliding bearings, roller bearings have a very low friction that is essentially independent of the load at the roller bearing. This then ensures that the stub axle can experience the said resistance to rotation that is defined by the said components essentially independently of the load to which the steering spindle arrangement is exposed during operation of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

One preferred embodiment of the invention will be described below with reference to the attached drawings, of which: Figure 1 shows a steering spindle arrangement according to present invention and Figure 2 shows a cross-sectional view of the steering spindle arrangement in the plane A- A in Figure 1. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE

INVENTION

Figure 1 shows a section through one end of an axle beam 1 in a vehicle. The axle beam 1 is provided with a conical hole la for the attachment of a spindle bolt 2. The spindle bolt 2 has a corresponding conical central part 2b that comprises the hole la with which the spindle bolt 2 is attached at the axle beam 1. The spindle bolt 2 has an upper part 2a with a cylindrical form and a lower part 2c with a cylindrical form. A steerable and non-driving wheel of the vehicle is adapted to be attached at a stub axle 3 that is arranged such that it can rotate around the spindle bolt 2. The stub axle 3 has an upper arm 4 with a first penetrating hole 5 for the reception of the upper part 2a of the spindle bolt, and a lower arm 6 with a second penetrating hole 7 for the reception of the lower part 2c of the spindle bolt. The upper part 2a of the spindle bolt is fixed into the first penetrating hole at the of the arm 4 with the aid of a conical roller bearing 8. The conical roller bearing 8 comprises an inner ring 8a that is fixed attached around the upper part 2a of the spindle bolt and an outer ring 8b that is fixed against an outer wall surface of the penetrating hole 5. A first bearing cover 10 closes an upper opening at the first penetrating hole 5. The bearing cover 10 comprises a threaded part that is adapted to be fixed by screwing into a threaded part 11 that is arranged at an upper part of the first penetrating hole 5. An axial needle roller bearing 12 is arranged in a position between the stub axle 3 and the axle beam 1. The needle roller bearing 12 is arranged in a transition region between the central part 2b of the spindle bolt and the upper part 2a of the spindle bolt. The needle roller bearing 12 comprises a first upper ring 12a that is connected to a plane contact surface at the stub axle 3, and a second lower ring 12b that is united with a plane contact surface at the axle beam 1. A first elastic seal 9 is arranged radially external to the needle roller bearing 12 in connection with a lower opening at the first penetrating hole 5. The first elastic seal 9 prevents dirt entering the needle roller bearing 12. The first elastic seal 9 prevents also dirt entering the conical roller bearing 8 through the lower opening at the first penetrating hole 5.

The lower arm 6 of the stub axle 3 comprises a second penetrating hole 7. A spherical roller bearing 13 is arranged in the second penetrating hole 7. The spherical roller bearing 13 comprises an inner ring 13a that is fixed attached around the lower part 2c of the spindle bolt, and an outer ring 15 that is fixed against an outer wall surface of the penetrating hole 7. A second elastic seal 16 is arranged at a position above the conical roller bearing 13 in connection with an upper opening to the second penetrating hole 7. A second bearing cover 17 closes a lower opening at the second penetrating hole 7. The bearing cover 17 is screwed in place with screws 18. The bearing cover 17 is provided with an O-ring 19. The second bearing cover 17 and the second elastic seal 16 provide a closed seal that prevents dirt entering the spherical roller bearing 13. The spindle bolt 2 has a longitudinal central axis that constitutes an axis of rotation 14 for the stub axle 3 when it is rotated around the spindle bolt 2 with the aid of the conical roller bearing 8 and the spherical roller bearing 13.

The first part 2a of the spindle bolt is provided with a threaded part at an upper end. A castle nut 21 is applied at the threaded part. It is possible to give the conical roller bearing 8 a suitable prestress with the aid of the castle nut 21. A first component in the form of a sheath 22 is arranged at an internal surface of the penetrating hole 5. Figure 2 shows a sectional view through a part of the upper arm 4 of the stub axle where the sheath 22 can be seen from above. The drawing makes it clear that the sheath 22 is ring-shaped and that it has an internal edge surface 22a that is located at a varying distance from the axis of rotation 14. The internal edge surface 22a forms an extended contact path that extends around the spindle bolt 2. The sheath 22 has an external edge surface 22b with a magnitude and form that correspond to those of an internal surface at the penetrating hole 5. The upper arm 4 at the stub axle 3 is provided with a first part 25a at an indentation, and the sheath 22 is provided with a second part 25b of the indentation that is arranged in a transition region between the upper arm 4 and the sheath 22. A first locking pin 24 is adapted to be introduced into the indentation in order to provide a connection that does not allow rotation between the upper arm 4 and the sheath 22. The sheath will in this way be rotated with the stub axle 3 when it is rotated relative to the spindle bolt 2.

A second spring-loaded component 23 is arranged radially internal to the sheath 22. The second spring-loaded component 23 comprises a central part with holes 23 c that have a magnitude and form that correspond to those of a peripheral surface of the first part 2a of the spindle bolt 2. The spring-loaded component 23 can in this way be placed onto and fixed around the first part 2a of the spindle bolt 2. The spring-loaded component comprises two radially protruding parts. Each one of the radially protruding parts comprises three parts 23b with slits, which parts have a curved form that causes them to have spring-loaded properties in at least one radial direction relative to the extended spindle bolt 2. Each one of the slitted parts 23b is provided with a peripheral surface 23 a that constitutes a contact surface with the internal edge surface 22a of the sheath. The spindle bolt 2 is provided with a first part 27a of an indentation, and the spring-loaded component 23 is provided with a second part 27b of an indentation that is arranged in a transition region between the spindle bolt 2 and the spring-loaded component 23. A second locking pin 26 is adapted to be inserted into the indentation in order to provide a connection that does not allow rotation between the spindle bolt 2 and the spring-loaded component 23. The spring-loaded component 23 is in this way prevented from being rotated when the stub axle is rotated relative to the spindle bolt 2.

Thus the sheath 22 constitutes a component that is rotated together with the stub axle 3, and the spring-loaded component 23 thus constitutes a component that is retained in place in a fixed rotary position together with the spindle bolt 2. The sheath 22 will in this way be rotated relative to the spring-loaded component 23 when the stub axle 3 is rotated relative to the spring-loaded component 23. The extended contact path 22a of the sheath extends here a complete revolution around the spring-loaded component 23. The contact path 22a of the sheath is arranged at a varying distance from the axis of rotation 14. The contact surfaces 23 a of the spring- loaded component are arranged at a constant distance from the axis of rotation 14 when in an unloaded condition. The spring-loaded parts 23b of the component that are connected with the contact surfaces 23 a thus have spring-loaded properties in a radial direction. The spring-loaded component 23 can in this way be arranged radially internal to the sheath 22. The contact surfaces 23a of the spring-loaded component are here arranged in contact with the extended contact path 22a of the sheath. The contact surfaces 23 a of the spring- loaded component are here arranged at a corresponding radial distance from the axis of rotation 14 as a part of the contact path 22a. The contact surfaces 23a of the spring- loaded component are pressed with a spring-loaded force radially outwards towards corresponding a radially externally arranged part of the contact path 22a. In this way a frictional resistance is formed, when the sheath 22 is rotated relative to the contact surfaces 23 a of the spring-loaded component, which resistance is inversely related to the distance of the contact surfaces 23a from the axis of rotation 14. The resistance to rotation can, with the aid of the form of the contact path 22a, which thus defines the radial distance of the contact surfaces 23a from the axis of rotation 14, be given the desired values at different angles of rotation. Figure 2 shows how the spring-loaded component 23 is arranged relative to the sheath 22 when the stub axle 3 is in an initial position at which the stub axle demonstrates an angle of rotation of 0° relative to the spindle bolt 2. The steerable wheel at the stub axle is here in a non-rotated condition. The contact surfaces 23a of the spring-loaded component are here in contact with the parts of the contact surface 22a of the sheath that are located at a maximal distance from the axis of rotation 14. When the steerable wheel at the stub axle 3 is rotated relative to the spindle bolt 2, the sheath 22 undergoes a corresponding rotation movement relative to the spring-loaded component 23 a. The contact surfaces 23 a of the spring-loaded component here come into contact with parts of the contact surface 22a of the sheath that are located at progressively shorter distance the axis of rotation 14. The resistance to rotation thus increases progressively since the radially spring-loaded parts 23b of the spring-loaded component press the contact surfaces 23 a progressively harder against the contact path 22a of the sheath. The contact path 22a of the sheath has a corresponding design on both sides of the angle of rotation 0°, such that the resistance to rotation increases in a corresponding manner, independently of the direction in which the stub axle 3 is rotated relative to the spindle bolt 2. Given knowledge of the particular vehicle, it is possible to estimate a desired value of the resistance to rotation that the stub axle 3 is to experience at different angles of rotation relative to the spindle bolt 2. The contact path 22a of the sheath is here formed such that a desired resistance to rotation is obtained for all individual angles of rotation or for different ranges of angle. Since the bearings are constituted by only roller bearings 8, 13, they demonstrate a very low friction that is essentially independent of the load on the stub axle. Thus the stub axle 3 experiences a resistance to rotation that is essentially defined only by the spring force with which the contact surfaces 23 a make contact with the contact path 22a. The invention is not in any way limited to the embodiment that has been described in the drawings: it can be freely varied within the scope of the patent claims. It is obvious that the steering spindle arrangement can be mounted such that the upper end and the lower end exchange positions.

Claims

1. A steering spindle arrangement that comprises a spindle bolt (2), an axle beam (1) that is attached at a central part (2b) of the spindle bolt (2), and a stub axle (3) that comprises a first penetrating hole (5) with a first bearing (8) for the reception of a first part (2a) of the spindle bolt (2), and a second penetrating hole (7) with a second bearing (13) for the reception of a second part (2c) of the spindle bolt (2), characterised in that the steering spindle arrangement comprises a first component (22) that is connected in a manner that does not allow it to rotate to the stub axle (3), a second component (23) that is connected in a manner that does not allow it to rotate to the spindle bolt (2), whereby the said components (22, 23) are in contact with each other at a contact area such that different resistances to rotation between the components (22, 23) are created at at least two angles of rotation between the stub axle (3) and the spindle bolt (2).

2. The steering spindle arrangement according to claim 1, characterised in that one of the said components (22) comprises an extended contact path (22a) and that the second component (23) comprises at least one contact surface (23 a) that is adapted to move in contact with the extended contact path (22a) when the stub axle (3) is rotated to different angles of rotation relative to the spindle bolt (2).

3. The steering spindle arrangement according to claim 2, characterised in that the contact surface (23 a) is pressed with a spring force against the contact path (22a) and that the resistance to rotation is related to the spring force with which the contact surface (23a) is pressed against the contact path (22a) at different angles of rotation.

4. The steering spindle arrangement according to claim 3, characterised in that the contact surface (23 a) is pressed against the contact path (22a) with a spring force in at least one radial direction relative to a central longitudinal axis (14) of the spindle bolt (2).

5. The steering spindle arrangement according to any one of the preceding claims 2 to 4, characterised in that the component that comprises the contact path is constituted by a ring-shaped sheath (22) and that the contact path is constituted by an internal edge surface (22a) of the sheath (22).

6. The steering spindle arrangement according to claim 5, characterised in that the said sheath (22) has an external edge surface (22b) that is adapted to be brought into contact with an internal surface of the first penetrating hole at the stub axle (3).

7. The steering spindle arrangement according to any one of the preceding claims, characterised in that the steering spindle arrangement comprises a locking pin (24), an indentation that comprises a first part (25 a) at the stub axle and a second part (25b) at the first component (22), whereby the locking pin (24) is adapted to be applied in the said indentation in order to create the said connection that does not allow rotation between the stub axle (3) and the first component (22).

8. The steering spindle arrangement according to any one of the preceding claims 2 to

7, characterised in that the said component (23) that comprises the contact surface (23a) comprises a spring-loaded part (23b) that is connected to the contact surface (23a), and a central opening (23c) with which the component (23) is applied around the spindle bolt (2).

9. The steering spindle arrangement according to any one of the preceding claims, characterised in that the steering spindle arrangement comprises a locking pin (26), an indentation that comprises a first part (27a) at the spindle bolt (2) and a second part (27b) at the second component (23), whereby the locking pin (26) is adapted to be applied in the said indentation in order to create the said connection that does not allow rotation between the spindle bolt (2) and the second component (23).

10. The steering spindle arrangement according to any one of the preceding claims, characterised in that the said bearings are roller bearings (8, 13).