FR2760408A1 - ADJUSTABLE FRICTION SHOCK ABSORBER AND VEHICLE AXLE HAVING SUCH A SHOCK ABSORBER - Google Patents

Abstract

The adjustable friction damper (1), in particular for an axle of a motor vehicle, comprises a pressure chamber (5), in which an adjusting piston (7) is movably arranged, which acts on an element of friction (9) so as to prevent movements, as a function of parameters which characterize the movements of the vehicle. Oscillatory movements of a vehicle wheel (13) are transmitted to the friction element, these movements being damped by the friction connection between the friction element and the adjusting piston.

Description

The present invention relates to an adjustable friction damper for

a motor vehicle.

  In motor vehicles, a telescopic oscillation damper is usually used to damp the oscillatory movements of the wheels, in which the damping effect is due to the throttling of the damping oil via throttle openings in an oscillation damper valve. This principle assumes that the wheel suspension stroke can be described jointly by the oscillation damper. However, aerodynamically refined bodies have a relatively flat cover and can therefore barely house the vertically arranged oscillation dampers. A fundamental problem in hydraulic oscillation dampers is that the smallest leaks or smallest deviations in the throttles cause the target curve to change for

damping force.

  The objective of the present invention is to provide a shock absorber for the wheels of a motor vehicle, which can also be used when the mounting space is reduced, and which is exact as to the

  curve provided for the damping force.

  According to the invention, this objective is achieved by means of an adjustable friction damper which comprises a pressure chamber in which an adjustment piston is movably arranged, said piston acting so as to prevent the displacement of a friction element , depending on parameters which characterize the movement of the vehicle, and oscillatory movements are transmitted to the friction element from a wheel of the vehicle, which are damped by the connection

  friction between the friction element and the adjusting piston.

  In its structure, a friction damper is simpler than a hydraulic oscillation damper. There is no need for specific designs of throttle valves. The only parameter of

  adjustment is the pressure of the adjusting piston which must be adjusted opposite

  screw of a target curve for the damping force. According to an advantageous embodiment, the friction element is controlled by a transmission lever, which is rotatably mounted on a frame fixed relative to the structure of the vehicle. As a transmission lever, it is perfectly possible to use a longitudinal arm of an axle of the vehicle. With the transmission lever, the stroke of the friction element can be significantly reduced in relation to the stroke

wheel damping.

  In order to achieve a compact embodiment, the pressure chamber forms, together with the adjusting piston, part of the mount. In this case, the adjusting piston protrudes from the end side out of the pressure chamber, and this same end is directed towards the friction element. Consequently, the friction element is open and can be licked by the circulating air current,

  so that heat is dissipated.

  To increase the damping force that can be obtained, the mount has a friction surface for the friction element, so that the friction element can be clamped between the adjusting piston and the friction surface. In practice, there are two friction surfaces

for the friction element.

  It is further provided that the friction element has the shape of a disc segment. In order to advantageously use the forces of the adjusting piston, the transmission lever with the friction element is produced in the form of a lever with one arm. For the same lever length, a lever arm ratio more advantageous for the adjusting piston is obtained with a single-lever transmission lever. In another advantageous embodiment, the pressure chamber is connected to a hydraulic system, and at least one valve is provided which regulates the flow connection to the pressure chamber, and which is influenced by means of an algorithm stored in a calculator. To regulate the valve a sensor arrangement is used which provides a signal with a sign representing the movement of the wheel. In particular, the relative movement between the wheel and the structure of the vehicle must be captured in order to be able to adjust the

  damping force regardless of direction.

  The invention also relates to a vehicle axle which comprises a vehicle wheel, which performs a damping movement with respect to a structure of the vehicle, comprising arms guided by means of pivot bearings to guide the vehicle wheel, said bearings performing, with the damping path of the vehicle wheel, a rotational movement relative to an axle part and / or to the structure of the vehicle, in which the vehicle axle comprises, in accordance with the invention, an oscillation damper produced in the form of a rotary oscillation damper, and the oscillation damper being driven on the input side by at least one arm. Advantageously, the rotary oscillation damper is produced under

  form of an adjustable friction damper.

  The invention will be explained in more detail using the description of

  figures which will follow. The figures show: FIG. 1, an illustration of the principle of the global system; Figure 2 a view of the transmission lever; Figure 3 a valve variant for the hydraulic system; and figures 4 to 8 of vehicle axles with an oscillation damper

  rotary corresponding to the overall system of figure 1.

  Figure 1 shows a principle representation of the overall system of an adjustable friction damper 1 in combination with a hydraulic system 3. The friction damper 1 proper comprises a pressure chamber 5, in which is arranged an adjustment piston 7 axially movable. The adjusting piston protrudes from the end side out of the pressure chamber and it is directed towards a friction element 9. The friction element is in active connection with a transmission lever 11, which in turn is connected to a wheel 13 of the vehicle, so that a damping movement of the wheel 13 of the vehicle is transmitted to the friction element. The transmission lever is held with the ability to rotate relative to a structure 17 of the vehicle, by means of a bearing 15. Thanks to this, the suspension movement of the vehicle wheel is converted into a tilting movement of

the friction element.

  The mounting 14 of the pressure chamber with the adjusting piston is part of a mounting 19 which is fixed to the structure 17 of the vehicle, or on the axle of the vehicle in a fixed position relative to the structure of the vehicle. A friction surface 21 belongs to the mount, so that the friction element 9 can be clamped between the adjusting piston and

the friction surface.

  The hydraulic system 3 is supplied with pressurized fluid, for example oil from a reservoir 27, by means of a pump 25 driven by an engine 23 of the vehicle. In the flow connection to the friction damper 1 are arranged a pressure regulating valve 29 and a switching valve 31. The two valves are controlled electrically from a computer 33 which calculates its adjustment signals based on on signals from an arrangement of sensors 35 which capture the movements of the vehicle. The possible signals that can be exploited are the speed V of the vehicle, the angle 4) of direction, the transverse and vertical accelerations, and in particular the relative movement between the wheel and the superstructure of the vehicle are ", since the movement relative allows to describe the rising / falling situation of the damping of the wheel of the vehicle, in order to ensure a damping of the wheel of the

  vehicle regardless of direction.

  The force which the adjusting piston exerts on the friction element 9 is determined by the pressure regulating valve 29. For the application of the force, or for the release, there is provided the switching valve which connects the pump 25 to the pressure chamber in a switching position, and which establishes the pressureless connection to the reservoir 27 in a second switching position. No large volumetric current should be displaced, so that adjustment of the friction damper is possible at high frequency. Pressure peaks due to the pump are compensated by a

accumulator 37.

  During a downward / upward movement of the suspension, the vehicle wheel moves approximately perpendicular to the plane of representation of FIG. 1. The suspension movement is transmitted by the transmission lever 11 to the friction element. In Figure 2 there is illustrated a view of the transmission lever, where it can be seen that the friction element must only be a disc segment, since only a tilting movement is carried out. It may also be advisable for the friction element and the connection of the transmission lever to the vehicle wheel to be made on the same side of the transmission lever, with respect to the mounting location 15, from

  so that one has a single-arm transmission lever.

  Figure 3 shows in the hydraulic system 3 a variation with respect to the pressure regulating valve 29. In this embodiment, an embodiment of a pressure regulating valve has been shown which has a third connection to the tank 27. By comparison with FIG. 1, another valve and a synchronization of the switching valve 31 are saved for the return to the pressure regulating valve 29, so that a total increase in system speed is achieved. in general. A vehicle axle 100 with a rotary oscillation damper 101 shows an application for the adjustable friction damper, and the vehicle axle shown in top view in Figure 4 has

  as arm 103 an oblique arm which is connected to the wheel 105 of the vehicle.

  The oblique arm is connected to a component arranged in a fixed position relative to the superstructure of the vehicle, for example a subframe 107. Use is made as pivoting bearings 109 known per se, which are here illustrated only schematically . The rotary oscillation damper is arranged in the pivot axis of the oblique arm. If necessary, the pivoting bearings can be made resiliently in order to avoid stresses. A transmission lever 1 1 1 ensures the application of the displacements of the wheel 105 to the rotary oscillation damper 101

via the oblique arm 103.

  In Figure 5, there is schematically a top view of a vehicle axle 100 in the form of an axle with transverse arms. The principle of the arrangement of the rotary oscillation damper 5 corresponds exactly to FIG. 4, which should be clearly expressed by the use of identical reference numerals for identical or similar components. In this example also, the axis of the rotational oscillations of the rotary oscillation damper

  is arranged in the tilting axis of the vehicle axle.

  Figure 6 shows a front view of a double axle with transverse arms, in which one of the rotation bearings 109 must be movable in an elastic manner, in order to compensate for the over-determination

  guiding the wheel 105 of the vehicle.

  In Figure 7 there is shown the front view of the axle 100 of the vehicle, and the problem of over-determination of the mounting of the arms is solved by providing that the transmission lever 111 is subdivided into two as regards mobility angular, so that no longitudinal stress can occur due to paths

  curved different from the articulation points of the rotation bearings 109.

  In a vehicle axle 100 which has the structure of a three-dimensional arm axle, it is also possible to use a shock absorber

  of rotary oscillations 101, as shown in FIG. 8.

Claims (11)

Claims   1. Adjustable friction damper (1) for a motor vehicle, comprising a pressure chamber (5), in which an adjustment piston (7) is movably arranged, which acts on a friction element (9) so to prevent displacements, as a function of parameters which characterize the movements of the vehicle, and oscillatory movements of a vehicle wheel (13) are transmitted to the friction element, said movements being damped by the connection to   friction between the friction element and the adjusting piston.   2. Adjustable friction damper according to claim 1, characterized in that the friction element (9) is controlled by a transmission lever (11), which is rotatably mounted on a mount (19)   fixed relative to a vehicle superstructure (17).   3. Adjustable friction damper according to claim 2, characterized in that the pressure chamber (5) with the adjustment piston (7) makes part of the frame (19).   4. Adjustable friction damper according to claim 1, characterized in that the adjustment piston (7) protrudes from the side of the end outside the pressure chamber (5) and in that the same end is   directed towards the friction element (9).   5. Adjustable friction damper according to claim 3, characterized in that the mount (19) has a friction surface (21) for the friction element (9), so that the friction element can be   clamped between the adjusting piston (7) and the friction surface.   6. Friction damper with adjustable friction according to claim 2, characterized in that the friction element (9) has the form of a disk segment.   7. Adjustable friction damper according to claim 2, characterized in that the transmission lever (11) with the friction element (9)   is made in the form of a lever with only one arm.   8. Adjustable friction damper according to claim 1, characterized in that the pressure chamber (5) is connected to a hydraulic system (3), in which at least one valve (29; 31) which regulates the flow connection towards the pressure chamber is influenced at   using an algorithm stored in a computer (33).   9. Adjustable friction damper according to claim 8, characterized in that one uses for the regulation of the valve (29; 31) a sensor arrangement (35) which prepares a signal endowed with a sign ae ",   which represents the movements of the wheel.   10. Vehicle axle, comprising a vehicle wheel which performs suspension movements relative to a vehicle superstructure, arms guided by means of pivot bearings to guide the vehicle wheel, which execute with the suspension path of the wheel rotational movement relative to a part of the axle and / or to the vehicle superstructure, characterized in that the vehicle axle comprises an oscillation damper produced in the form of a rotary oscillation damper, and at least one arm   attack on the input side of the oscillation damper.   11. Vehicle axle according to claim 10, characterized in that the rotary oscillation damper is produced in the form of an adjustable friction damper according to any one of claims 1 to 9.