Land vehicles – Wheeled – Running gear
Patent
1998-02-03
2000-04-11
Johnson, Brian L.
Land vehicles
Wheeled
Running gear
B62D 1502
Patent
active
060479779
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a steering lock end-stop for a suspended and steerable vehicle wheel unit.
In particular, but not exclusively, the invention relates to sprung front wheel assemblies of light vehicles such as passenger cars, buses and trucks. The front wheel assemblies may also comprise driven wheels.
BACKGROUND TO THE INVENTION
A vehicle having a steering lock end-stop as defined in the preamble of claim 1 is known from the front wheel drive Volvo 850 passenger car. In this vehicle, an abutment member made of rubber is attached by rivets to the front surface of each of the wishbones on the front suspension.
The reason for having an end-stop is that when the steered wheels of a vehicle are turned to the maximum, i.e. when the steering is put on to full lock, it is important that the moving wheel rim or tire, or any other parts of the wheel unit, cannot come into contact with any other parts of the car. Thus by providing such an end-stop, the wheel is prevented from being turned too far. By making the end stop of rubber, any metal-to-metal contact between the abutting surfaces of the end stop and the steered part of the wheel can also be prevented, which helps to reduce noise.
Whilst such a solution is an improvement over previously existing systems, it has been noticed that with frequent driving on full lock, such end stops become worn and may require replacement. This is particularly the case with driving on full lock on uneven ground. Moreover such wear will occur, even though the two abutting surfaces undergo the same angular deflections as the vehicle suspension arm (since both abutting surfaces are attached directly or indirectly to the suspension arm).
Additionally, due to the contact between the metal and rubber parts, a creaking or juddering sound may be experienced.
The main object of the invention is thus to provide a solution to the aforementioned problems.
A further problem which also arises is that when the steering is on full lock and the vehicle is driven over uneven ground, the wheels and suspension may undergo large upward and downward movements. Unless suitable measures are taken, the wheels would come into contact with other stationary parts of the vehicle during such large suspension movements. This leads to noise and/or damage. Additionally, if the wheels are driven wheels as well as being steered wheels, it also needs to be ensured that the constant velocity joints (CV-joints) are not subjected to angles outside their range of operation. These difficulties can be avoided in the prior art by providing the end stop at a location which is positioned so as to limit turning of the wheel to a fixed amount which prevents all possible contact at all suspension deflections. At the same time, the chosen location should also prevent excessive angular displacements between the input and output shafts of the CV-joints. However, the result of this end-stop positioning is that the turning circle for the vehicle is then somewhat larger than is actually required when driving on even ground with the suspension in its normal position.
A larger turning circle makes the car less-easily manouevrable and is thus undesirable.
Thus, in a preferred aspect, it is a further object of the invention to solve this problem, so that a tighter turning circle can be achieved without compromising the ability of the end-stop to prevent contact of the wheel with other parts of the vehicle.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other objects have now been realized by the invention of a steering lock end-stop for a suspended and steerable wheel unit which comprises a first abutment member affixed to a first portion of the vehicle, and a second abutment member at a location selected for abutment with the first abutment member and affixed to the suspended and steerable wheel unit, whereby the second abutment member is correspondingly displaced with both steering and suspension displacement of the wheel unit, one of the first and second abutment membe
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patent: 5435590 (1995-07-01), Larsson
AB Volvo
Britton Michael
Johnson Brian L.
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