Steering spindle arrangement

(12) Patent Specification (, SE> SE 537 309 C2

Sweden (21) Patent Application Number:

(45) Patent granted:

(41) Application publicly available:

(22) Filing date:

(24) Running day:

(30) Priority information:

1250669-7

2015-04-07

2013-12-22

2012-06-21

2012-06-21 (51) lnt.CI .:

B62D 7/18 (2006.01)

<td>(73) Patent holders:</td><td>Scania CV AB, 151 87 Södertälje SE</td>

<td>(72) Inventor:</td><td>Martin STARS, Farsta SE</td>

<td>(74) Agents:</td><td>Bjerkéns Patentbyrå KB, Box 5366, 102 49, Stockholm SE</td>

<td>(54) Name:</td><td>A steering spindle arrangement</td>

<td>(56) Publications cited:</td><td>EP 1477388 B1 US 20040262875 A1 US 3479051 A</td>

(57) Summary:

The present invention relates to a guide spindle arrangement comprising a spindle bolt (2), a shaft beam (1) fixed to a central part (2b) of the spindle bolt (2), a shaft pin (5) having a first arm (6) rotatably arranged about a first part (2a) of the spindle bolt (2) via a first bearing (11) and a second arm (8) rotatably arranged around a second part (2c) of the spindle bolt (2) via a second bearing (22). The spindle arrangement includes adjusting mechanism (4, 18) with which it is possible to set a variable torque for the shaft (5) as it is rotated round the spindle bolt (2).

<img file="SE537309C2_D0001.tif" />

537 309

Summary

The present invention relates to a guide spindle arrangement comprising a spindle bolt (2), a shaft beam (1) fixed to a central part (2b) of the spindle bolt (2), a shaft pin (5) having a first arm (6) rotatably arranged about a first part (2a) of the spindle bolt (2) via a first bearing (11) and a second arm (8) rotatably arranged around a second part (2c) of the spindle bolt (2) via a second bearing (22). The spindle arrangement includes adjusting mechanism (4, 18) with which it is possible to set a variable torque for the shaft (5) as it is rotated round the spindle bolt (2).

537 309

A steering spindle arrangement

BACKGROUND OF THE INVENTION AND PRIOR ART

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

A steering spindle arrangement for a steerable wheel in a vehicle usually includes a steering spindle bolt with a conical shaped portion for attaching an axle beam. A shaft bearing the wheel is pivotally mounted on the guide spindle bolt by means of an upper bearing which may be a tapered roller bearing and a lower bearing which may be a plain bearing. In this case, the upper bearing absorbs both axial and radial forces while the lower bearing absorbs radial forces. Most roller bearings, however, need to be biased to eliminate play in the roller bearing. One known way to bias bearings is to use shims. By means of appropriately placed shims, the inner ring and outer ring of the roller bearing can be loaded with a force so that the bearing play is eliminated. However, mounting shims is complicated and does not always produce the desired effect.

WO 97/13674 discloses a spindle bolt threaded at both an upper end and a lower end. An upper nut is attached to the upper thread and a lower nut is attached to the lower thread. By means of the upper nut, an inner ring of an upper tapered roller bearing can be locked against a surface of the shaft beam. With the help of the lower nut, the upper taper roller bearing and a lower taper roller bearing can be biased. In this case, no shims are needed to bias the roller bearings. Since the lower nut is used to bias both the lower roller bearing and the upper roller bearing, forces are transferred from the nut both to a lower arm and to an upper arm by a bearing pin. This force load on the arms of the bearing pin results in elastic deformation of the bearing pin. Biasing a roller bearing by means of an elastically deformed component is not suitable. Roller bearings should be attached and pre-tensioned between two substantially rigid surfaces.

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It is preferable that vehicle wheels arranged on a pivotal shaft pin be rotated around a spindle bolt with a suitable torque resistance. If the torsion resistance is too small, there is a risk that vibrations will occur in the motion-transmitting transmission that transmits steering movements from the steering wheel of the vehicle to the steerable wheels. If the torsion resistance is too large, an unnecessarily large force is required to turn the wheels.

SUMMARY OF THE INVENTION

The object of the present invention is to provide guide spindle arrangements where it is possible to provide an adjustable torsion resistance for a shaft pin rotated around a spindle bolt.

This object is achieved with guide spindle arrangements of the type mentioned in the introduction, which is characterized by the features defined in the characterizing part of claim 1. In this case, therefore, an adjusting mechanism is used which makes it possible to set a desired torque resistance for the shaft pin as it is rotated around the spindle bolt. Thus, a controllable vehicle wheel arranged on the shaft pin can be rotated with a desired torque resistance around the spindle bolt. With this, vibrations in the steering wheel of the vehicle can be avoided at the same time as no excessive force is required to turn the wheel and steer a vehicle.

According to the invention, the adjustment mechanism comprises a sliding bearing which is arranged in a position between the shaft and the shaft and a clamping device with which it is possible to create a variable force which pushes the shaft and the shaft against the sliding bearing so that the shaft receives a desired resistance as it is rotated about the spindle bolt. The torque resistance is here related to the compressive force with which the shaft pin and the shaft beam are pressed against the sliding bearing. Although the shaft and the shaft are pressed against the sliding bearing with a relatively large compressive force, the sliding bearing guarantees that the shaft can substantially always provide a rotational movement relative to the spindle bolt.

According to an embodiment of the present invention, the sliding bearing is annular and arranged around the spindle bolt in an area between the first part of the spindle bolt and the intermediate part of the spindle bolt. In this area, the sliding bearing can make contact with both the shaft pin and the shaft beam. The sliding bearing has a first sliding surface on a first side which is in contact with a contact surface of the first arm of the shaft and a second sliding surface on a second side which is in contact with a contact surface of the shaft beam. The slide bearing is included

537 309 advantage a flat first sliding surface which is in contact with a flat contact surface of the shaft pin and a flat second sliding surface which is in contact with a flat contact surface of the shaft beam. Said flat contact surfaces preferably have a propagation in a perpendicular plane with respect to a longitudinal axis through the spindle bolt.

According to one embodiment of the present invention, the sliding bearing is made of a rigid metal material. Thus, the sliding element provides essentially no elastic deformation when subjected to said compressive force. The sliding element is advantageously made of a steel material that is durable and resistant to corrosion.

According to an embodiment of the present invention, the clamping device comprises a nut rotatably arranged on a threaded portion of a first end of the spindle bolt. The nut may have a surface which is in direct or indirect contact with a surface of the shaft pin. The shaft beam is advantageously attached to a conically shaped intermediate part of the spindle bolt. By tightening the nut, the nut in contact with the shaft pin and the spindle bolt which is in contact with the shaft beam will be displaced in an axial direction towards each other so that the contact surface of the shaft pin and the contact surface of the shaft beam is pressed against the opposite sliding surfaces of the sliding ring. By adjusting the torque of the nut, the contact surface of the shaft pin and the contact surface of the shaft beam can be pressed against the opposite sliding surfaces of the sliding ring with a variable pressure resulting in the shaft pin obtaining a torsional resistance as it is rotated around the spindle bolt which is related to the torque of the nut.

According to an embodiment of the present invention, the first bearing is a roller bearing and the clamping device is adapted to create said compressive force against the sliding bearing, via the roller bearing, so that the roller bearing receives a biasing while the clamping device creates said compressive force acting on the sliding bearing. Roller bearings and in particular tapered roller bearings usually have to be pre-tensioned. Thus, in this case, the compressive force created by the clamping device to provide said torque resistance can also be utilized to bias the bearing. The roller bearing is advantageously a tapered roller bearing that can absorb both radial and axial forces.

According to an embodiment of the present invention, the roller bearing has an inner ring adapted to come into contact with said nut and an outer ring arranged in a valve seat in an arm of the shaft pin. In this case, a tightening of the nut is provided with a force transmitted from the nut, via the roller bearing, to the shaft pin so that

537 The contact surface of the shaft 309 is pressed against the first slide surface of the bearing. At the same time as the nut is tightened, the intermediate conical portion of the spindle bolt provides a movement which results in the contact surface of the shaft beam being pressed against the other sliding surface of the sliding bearing on the opposite side. In this case, both the nut and the roller bearing are arranged at the first part of the spindle bolt, at the same time as the sliding bearing is arranged in the area between the first part of the spindle bolt and the central part of the spindle bolt. The force from the nut here only loads part of the first arm of the shaft pin. Thus, the shaft pin does not receive substantially any elastic deformation as the case may be when both arms of the shaft pin are loaded. In this case, the roller bearing receives a substantially rigid bias.

According to an embodiment of the present invention, the spindle arrangement comprises a seal arranged around the spindle bolt in contact with the spindle bolt, the slide bearing and the first arm of the shaft pin. This prevents dirt from entering the roller bearing in connection with the slide bearing.

According to one embodiment of the present invention, the second layer is a sliding bearing. Thus, radial forces can be absorbed at the other part of the spindle bolt. The slide bearing is also advantageously protected against dirt penetration by means of suitable seals.

BRIEF DESCRIPTION OF THE DRAWINGS The following is a preferred embodiment of the invention with reference to the accompanying drawing, in which:

Fig. 1 shows a control spindle arrangement according to the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Fig. 1 shows a section through one end of a shaft beam 1 in a vehicle. The shaft beam 1 is provided with a conical shaped hole 1a for attaching a spindle bolt 2. The spindle bolt has a corresponding conically shaped central part 2c as the hole 1a with which the spindle bolt 2 is fixed to the shaft beam 1. The spindle bolt 2 has an upper part 2a with a cylindrical shape. and a lower portion 2c having a cylindrical shape. The upper portion 2a has a smaller diameter than the lower portion 2c. The upper part 2a of the spindle bolt 2 is provided with a threaded portion 3. A crown nut 4 is secured to the threaded portion 3. A not shown controllable

537 309 wheels of the vehicle are adapted to be secured to a shaft pin 5 pivotally arranged around the spindle bolt 2. The shaft pin 5 has an upper arm 6 with a first through hole 7 for receiving the upper part 2a of the spindle bolt and a lower arm 8 with a second through hole. 9 for receiving the lower part 2c of the spindle bolt.

The first through hole 7 of the upper arm 6 is provided with a bearing seat 10 for receiving a tapered roller bearing 11. The tapered roller bearing 11 has an inner ring 12 which is secured around the upper part 2a of the spindle bolt and an outer ring 13 which is arranged in the bearing seat 10. The bearing seat 10 has a stop surface 10a defining a mounting position for the outer ring 13. A first elastic seal 14 is provided at a lower opening of the first through-hole 7 in a position below the tapered roller bearing 11. The first resilient seal 14 prevents dirt from entering the tapered roller bearing 11 via the lower opening of the first through hole 7. A first bearing cap 15 closes an upper opening of the first through hole 7. The bearing cover 15 is screwed with threads 16 which are arranged at the upper opening of the first through-hole 7. A first O-ring 17 ensures that the first bearing cap 15 provides a tight closure of the upper opening of the first through hole 7 so that dirt cannot penetrate the tapered roller bearing 11 this way.

A sliding ring 18 of a rigid metal material, such as a steel material, is arranged around the spindle bolt 2 in a position below the first elastic seal 14. The sliding ring 18 is arranged in a boundary region between the central part 2b of the spindle bolt and the upper part 2a of the spindle bolt. The sliding ring 18 comprises a first flat upper sliding surface 18a which is in contact with a flat contact surface 19 of the shaft pin 5 and a second flat lower sliding surface 18b which is in contact with a flat contact surface 20 of the shaft beam 1. The lower arm 8 of the shaft pin 5 comprises a second through-hole 9 with a bearing seat 21 for receiving a sliding bearing 22. A second resilient seal 23 is arranged in a position above the sliding bearing in connection with an upper opening to the second through-hole 9. A second bearing lid 24 closes a lower opening of the second through-hole 9. The bearing cap 24 is screwed with threads 25. A second O-ring 26 ensures that the second bearing cap 24 provides a tight closure at the lower opening of the second through-hole 8. The second bearing cap 24 and the second resilient seal provide a tight enclosure that prevents dirt from entering the bearing layer 22.

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Before the first bearing cap 15 is screwed on, during a mounting process of the control spindle arrangement, the crown nut 4 is tightened. The crown nut 4 is screwed onto the threaded portion 3 of the upper part 2a of the spindle bolt until it comes into contact with an upper surface of the inner ring 12. The crown nut 4 is then tightened with a predetermined torque with the aid of a suitable tool. As the crown nut 4 is tightened, a lower surface of the crown nut 4 loads the inner ring 12 of the tapered roller bearing with a compressive force. This compressive force which seeks to push down the inner ring 12 is propagated to the outer ring 13 via the tapered rollers of the roller bearing 11. The force is then transferred from the outer ring f3 to the stop surface 10a of the bearing seat 10 which forms part of the upper arm of the shaft pin 5. The downward force finally acts on the shaft pin 5 so that the contact surface 19 of the shaft pin is pressed against the upper sliding surface 18a of the sliding bearing 18.

When the crown nut 4 is tightened, the spindle bolt 2 receives a short offset movement in an axial direction upwards relative to the crown nut 4. The conical central portion 2b of the spindle bolt transmits this movement to the shaft beam 1 which is displaced upwards by a corresponding distance so that the contact surface 20 of the shaft beam is pressed down against the sliding surface 20. 18b with a force related to the torque of the crown nut 4. Thus, when the crown nut 4 is tightened, the contact surface 19 of the shaft pin and the contact surface 20 of the shaft beam will be pressed against the sliding surfaces 18a, 18b of the sliding bearing 18 with a compressive force related to the tightening torque of the crown nut. The shaft pin 5 is thus rotatably positioned against the spindle bolt 2 with a rotational resistance defined by the compressive force with which the contact surface 19 of the shaft pin and the contact surface 20 of the shaft beam is pressed against the sliding bearing 18 which in turn is dependent on the torque of the crown nut 4. By tightening the crown nut with a suitable torque, the shaft pin can obtain a desired torque resistance when it is rotated with the spindle bolt 2. With the aid of the crown nut 4, the torque resistance can be adjusted in a very simple way if necessary.

Thus, the force transmitted from the crown nut 4 to the slide bearing 18 is conducted, via the target bearing 11 to the slide bearing 18. Thus, the inner ring 12 and outer ring 13 of the roller bearing 11 receive a bias relative to each other as the crown nut 4 is tightened. In this case, the force is conducted in a substantially vertical direction downward from the crown nut 4 to the slide bearing 18. The tapered target bearing 11 receives a bias defined by the crown nut 4 and the bearing surface 10a of the bearing seat. The crown nut 4 and the bearing surface 10a of the bearing seat are substantially rigid surfaces which provide a rigid biasing of the tapered target bearing 11. With a suitable dimensioning of the constituent components, the shaft pin 5 can obtain a desired torsional resistance as it is rotated along the spindle bolt 2 at the same time as the conical

537 309 roller bearing 11 obtain a suitable bias. With the help of the crown nut 4 and the slide bearing 18 an adjustment mechanism is obtained by which the torsional resistance of the shaft pin around the spindle bolt 2 can be varied steplessly and with good precision. The control spindle arrangement according to the above also permits a relatively simple mounting in a vehicle.

The invention is in no way limited to the embodiment described in the drawing but can be freely varied within the scope of the claims.

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