Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1999-06-08
2001-05-29
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
C267S064210, C267S122000, C188S322190
Reexamination Certificate
active
06237902
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a shock absorber arrangement which comprises a shock absorber combined with a wheel suspension fitting and which is arranged for active wheel suspension/shock absorbing in a wheel suspension of a vehicle.
BACKGROUND OF THE INVENTION
In order to ensure good road characteristics and good travelling comfort (comfortable driving) for a vehicle equipped with wheels, such as an automobile, and in the special case of travelling on rough surfaces and when driving around bends, the vehicle must be provided with a well functioning system of wheel suspension, shock absorbers and springs. The springs provide elastic resistance through storing energy when they are pressed together, and this energy is damped away at least partially by means of shock absorbers which brake the relative movement between the bodywork of the vehicle and the wheel suspension and convert the spring energy to heat.
Especially between the front wheels of the vehicle, but sometimes also between its rear wheels, there is usually some type of stabilizer which prevents excessive rolling (leaning to the side) of the bodywork when driving around bends. A usual type of stabilizer is a twist or torsion spring in the shape of a torsion rod which is rotatably mounted to the car body/chassis/base plate and which extends transversely to the longitudinal axis of the car. The ends of the torsion rod are connected to the wheel suspension by lever arms and follow their suspension movements. With differently sized suspension movements of the wheels connected together through the stabilizer the stabilizer counteracts the leaning of the bodywork when driving around corners outwards in the curve and presses the inner, lighter loaded wheel against the road surface. The outer, more heavily loaded wheel at the same time gets stiffer springing which together leads to reduced lean and thereby improved road characteristics.
A wheel suspension system with active springs can regulate both the spring function and the damping function of the wheels. A plurality of different constructive solutions concerning such systems are known in the prior art. Sensors can be included in these systems which sense, for example, the vertical wheel load, the movement of the wheel and acceleration, respectively.
Signals from the sensors are normally transmnitted to an electronic control unit which controls and influences the characteristics of the constituent components in the wheel suspension system, such as springs, shock absorbers and stabilizers.
Thus it is previously known to combine shock absorbers and wheel suspension fittings to form a shock absorber/spring unit, for example, in the shape of a hydraulic shock absorber with a surrounding helical spring (spiral spring) made of steel.
It is also known from the prior art to combine a stabilizer with a separate piston and cylinder device, which is arranged to, depending on at least one vehicle parameter, regulate the influence of the stabilizer on the wheel suspension system. Such a separate piston and cylinder device requires, however, for its mounting and in order to be able to perform its working movement, a not inconsiderable space in the vehicle. Near the rear axle the fuel tank is often in the way for such a device, and in the front of the vehicle the device must be placed under the engine which often is very problematic.
SUMMARY OF THE INVENTION
Quite generally, it must be stated that sufficient space for such a piston and cylinder device is not available in many of today's constructively compactly built motor vehicles, not least when it is a question of automobiles. A main object of the invention is therefore to provide a compact shock absorber arrangement for wheel suspensions in a vehicle, especially a motor vehicle of automobile type, where the spring effect, shock absorbing and stabilizing effect can be provided in a coordinated way with the help of a single constructively integrated unit. The main principle should thereby be that the unit is built up around the shock absorber which must in any case be given space in the region of the wheel suspension. The shock absorber arrangement according to the invention should also be so compact that it can find room at the front wheel of the vehicle as well as at its rear wheels.
A further object is that the shock absorber arrangement should be made so that the spring movement, shock absorber movement and the movement opposing leaning take place in the same direction, i.e. along a common line of action.
As is evident from the above, the shock absorber device should be so designed that it offers an effective means, which in a space-saving way is able to actively counteract leaning of the vehicle in question when it is driven through a curve.
Up to now, shock absorbers in combination with air springs have mainly been used in rear wheel suspensions but the shock absorber arrangement according to the invention through forming a constructively integrated unit can be used equally well in a front wheel suspension of a vehicle as in its rear wheel suspension. Air suspensions have in recent years become used more often because, among other things, they offer a soft vertical suspension and at the same time an improved travelling comfort. A disadvantage of air suspensions are, however, also that they lead to an increased susceptibility to leaning which is why special air suspensions should be combined with active lean-reducing measures so that the travelling comfort and the road-holding abilities should also be extremely good during cornering.
As a summary it could be said that the invention aims to offer a shock absorber arrangement with the same suspension characteristics the whole time, independent of the actual case of load of the vehicle, i.e. independent of the size of the load forces which influence, and which are to be absorbed by, the wheel suspension for the vehicle wheel in question.
The above mentioned object and therewith connected constructive problem is obtained and solved, respectively, according to the invention through a shock absorber arrangement having the characteristics stated in the claims.
Consequently, that which primarily distinguishes the shock absorber arrangement according to the invention is that the wheel suspension device is an air spring (an air cushion device) which surrounds the shock absorber itself, and in an annular space between the shock absorber and the air spring is mounted an annular piston and cylinder device which surrounds the shock absorber and which on the inside is connected to the shock absorber and on the outside is connected to the air spring. The piston in this piston and cylinder device is in this case an annular piston which is connected to a stabilizer belonging to the wheel suspension.
An important advantage of a shock absorber arrangement according to the invention is thus that, through forming a constructively integrated unit, it effectively avoids the building-in problems which follow with the mounting of the up to now known separate extra components for providing active shock absorbing with the use of pneumatic or hydraulic working cylinders cooperating with for example a stabilizer.
Preferred embodiments of the shock absorber arrangement according to the invention can furthermore have the characteristics stated in the dependent claims.
In one of the dependent claims it is stated especially how the piston and cylinder device suitably can be constructively designed so as to keep the outer dimensions of the device transversely (i.e. its diametric measurement) as low as possible.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described more closely with reference to the embodiments shown in the accompanying drawings, wherein
FIG. 1
shows in partially longitudinal section a shock absorber arrangement according to the invention;
FIG. 2
shows in lateral view and in diametrical cross-section the shock absorber with associated fastening nuts constituted in the shock absorber device according to the invention;
FIG. 3
shows in axial longitudinal sect
AB Volvo
Oberleitner Robert J.
Rodriguez Pamela J.
Young & Thompson
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