Land vehicles – Body elevation or tilt – Establishing riding or trim height
Reexamination Certificate
2000-03-27
2001-07-17
Culbreth, Eric (Department: 3611)
Land vehicles
Body elevation or tilt
Establishing riding or trim height
C180S209000, C280S005514, C280S006150
Reexamination Certificate
active
06260860
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to active vehicle suspensions which are operable to alter the ride height of a vehicle, and in particular to such suspensions which are independent suspensions.
BACKGROUND TO THE INVENTION
In most independent suspensions a change of ride height is accompanied by a change of track because the wheels are attached to suspension arms which pivot, usually about their inboard end, as the body is raised or lowered. The wheels therefore move relative to the body in an arc rather than a straight line. If the vehicle is stationary when the height change is occurring, the friction between the wheels and the ground can prevent the wheels from slipping sideways and therefore prevent or hinder the change of height. This can result in the vehicle becoming stuck at a ride height which is different from the desired ride height. A lot of energy can then be expended as the system tries to overcome friction, especially if the ride height is increasing. Also, when the vehicle starts to move the ride height, and track, can change with much less resistance, and this can lead to a sudden height change which is uncomfortable or disconcerting for the driver.
SUMMARY OF THE INVENTION
Accordingly the present invention provides an independent vehicle suspension system for connecting two wheels to opposite sides of a vehicle body, the system comprising two suspension arms each for connecting a respective one of the wheels to the body and being movable relative to the body so as to provide a variable ride height of the body relative to the respective wheel, two ride height control actuators each for changing the ride height of the vehicle body relative to one of the wheels, a controller arranged to receive ride height change request signals and to control the operation of the ride height control actuators, and a vehicle speed sensor for measuring a ground speed of the vehicle wherein, upon receipt of a ride height change request signal, the controller is arranged to send signals to the ride height control actuators to start the ride height change and, if the vehicle is stationary, at least under some conditions, to cease the ride height change before it has been completed, and if the vehicle ceases to be stationary, to complete the requested ride height change.
The control means may define a predetermined maximum ride height change and said conditions be that the requested ride height change is more than the maximum ride height change.
Alternatively the system may further comprise ride height sensors for detecting said conditions which are when the ride height does not change in the requested manner in response to receipt of a ride height change request signal.
Preferably the control means has defined therein a predetermined magnitude of rate of change of ride height, and is arranged to monitor the rate of change of ride height during the requested ride height change, and to detect said conditions by detecting that the rate of change with time falls below said predetermined magnitude.
Preferably the ride height control actuators are operated by a fluid, the system further comprises pressure sensors for measuring the pressure of the fluid, and the control means is arranged to monitor the pressure of the fluid and the ride height during the requested ride height change and to detect said conditions by detecting that the ride height does not vary in an expected manner with change in said pressure.
The fluid is preferably air, but hydraulically actuated systems can also be used.
The ride height change may be an increase or a decrease in ride height.
The suspension arms are preferably arranged such that a change of ride height of the wheels produces a change of track of the wheels. For example the suspension arms may be arranged to pivot relative to the body about respective axes which extend substantially longitudinally of the vehicle.
preferably the system further comprises wheel speed sensors for detecting whether the vehicle is stationary.
The present invention further provides an independent vehicle suspension system for connecting two wheels to opposite sides of a vehicle body, the system comprising two suspension arms each for connecting a respective one of the wheels to the body and being movable relative to the body so as to provide a variable ride height of the body relative to the respective wheel, two ride height control means each for changing the ride height of the vehicle body relative to one of the wheels, control means arranged to receive ride height change request signals and to control the operation of the ride height control means, and a vehicle speed measuring means for measuring a ground speed of the vehicle wherein, upon receipt of a ride height change request signal, the control means is arranged to send signals to the ride height control means to start the ride height change and, if the vehicle is stationary, at least under some conditions, to cease the ride height change before it has been completed, and if the vehicle ceases to be stationary, to complete the requested ride height change.
The present invention further provides an independent vehicle suspension system for connecting two wheels to opposite sides of a vehicle body, the system comprising two suspension arms each for connecting a respective one of the wheels to the body and being movable relative to the body so as to provide a variable ride height of the body relative to the respective wheel, two ride height control actuators each for changing the ride height of the vehicle body relative to one of the wheels, a controller arranged to receive ride height change request signals and to control the operation of the ride height control actuators, and a vehicle speed sensor for measuring a ground speed of the vehicle wherein, upon receipt of a ride height change request signal, the controller is arranged to send signals to the ride height control actuators to start the ride height change and, if the vehicle is stationary, to monitor the ride height during the ride height change and, if it does not change in an expected manner, to cease the ride height change before it has been completed, and if the vehicle ceases to be stationary, to complete the requested ride height change.
The present invention still further provides an independent vehicle suspension system for connecting two wheels to opposite sides of a vehicle body, the system comprising two suspension arms each for connecting a respective one of the wheels to the body and being movable relative to the body so as to provide a variable ride height of the body relative to the respective wheel, two ride height control actuators each for changing the ride height of the vehicle body relative to one of the wheels, a controller arranged to receive ride height change request signals and to control the operation of the ride height control actuators, and a vehicle speed sensor for measuring a ground speed of the vehicle wherein, upon receipt of a ride height change request signal, the controller is arranged to send signals to the ride height control actuators to start the ride height change and, if the vehicle is stationary and the requested ride height change exceeds a predetermined maximum ride height change, to change the ride height only by said predetermined maximum change, and then if the vehicle ceases to be stationary, to complete the requested ride height change.
Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings.
REFERENCES:
patent: 5180024 (1993-01-01), Eto
patent: 2292916A (1996-03-01), None
patent: 3-178819 (1991-08-01), None
patent: 3-178816 (1991-08-01), None
Brookes Graham Robert
Dixon Christopher David
Woodhouse Richard Graham
Culbreth Eric
Davis & Bujold P.L.L.C.
Rover Group Limited
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