Abstract
A spring-absorber system for a wheel suspension of a motor vehicle includes a suspension spring with a spring constant k.sub.T and an absorber filled with a fluid and mounted in parallel to the suspension spring. The spring-absorber system also includes at least two additional spring modules via which a total spring constant k.sub.G of the spring-absorber system can be varied.
Claims
1. A spring-absorber system for a wheel suspension of a motor vehicle comprising: a spring module including a suspension spring with a spring constant k.sub.T and an absorber connected in parallel with the suspension spring and filled with a fluid; and at least two additional spring modules, each containing a respective container, wherein each container includes a respective container volume which is subjected to pressure by a respective additional suspension spring with a respective spring constant k.sub.n, wherein the container volumes each have a flow connection via a respective fluid line to an absorber section of the absorber, wherein an absorber section volume of the absorber section is reduced during a compression stage of the absorber; wherein at least one additional spring module of the at least two additional spring modules includes a controllable shut-off valve with which the respective fluid line is blockable; wherein at least two additional spring modules of the at least two additional spring modules have a common cylinder comprising at least three cylinder chambers each separated by a separating piston, wherein a first cylinder chamber of the at least three cylinder chambers accommodates the respective additional suspension spring of one of the at least two additional spring modules and a third cylinder chamber of the at least three cylinder chambers accommodates the respective additional suspension spring of a second one of the at least two additional spring modules.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows a spring-absorber system with two additional spring modules.
(2) FIG. 2 shows a spring-absorber system with four additional spring modules.
(3) FIG. 3 shows a spring-absorber system with two additional spring modules formed integrally with each other.
DETAILED DESCRIPTION OF THE DRAWINGS
(4) The Figures are exemplary and schematic. The same reference characters in the Figures indicate the same functional and/or structural characteristics.
(5) FIGS. 1 to 3 each show a spring-absorber system according to the invention system, which differ only by the respective additional spring modules thereof. The vehicle body FK and the vehicle axle FA are supported against each other by the suspension spring 10, wherein the absorber 20 dampens the movements and the resulting forces. The absorber 20 is a cylinder supported on the vehicle body FK, into which the piston rod 24 extends from the vehicle axle FA. The piston rod 24 is fixed to a piston 23 in the cylinder and is thereby embodied to move the piston 23 in the cylinder by a movement of the piston rod 24. The cylinder of the absorber 20 is divided by the piston 23 into a first and a second absorber section 21, 22, each of which determine an absorber section volume. The absorber sections 21, 22 and the respective associated absorber section volumes reduce or increase depending on the movement of the piston rod 24 and the piston 23. If the piston rod 24 moves into the cylinder (compression stage), the first absorber section 21 and the associated absorber section volume become smaller and the second absorber section 22 and the associated absorber section volume become larger, if the piston rod 24 moves out of the cylinder (tension stage), the first absorber section 21 and the associated damping section volume will become larger, and the second absorber section 22 and the associated absorber section volume will become smaller.
(6) In FIG. 1 two additional spring modules 31, 32 are connected via a fluid line 30 to the first absorber section 21 or to the absorber section volume. The additional spring module 31 comprises an additional container as a cylinder 311 that is filled with the fluid. The fluid in the cylinder 311 is pressurized via the separating piston 313 by means of an additional spring 312, so that the spring force of the additional spring 312 exerts a pressure on the fluid, which is transferred via the fluid line 30 into the absorber 20 and through the absorber 20 to the vehicle body FK and the vehicle axle FA. As a result of the shut-off valve 324 of the second additional spring module 32 being in a position (shut-off position) that blocks the fluid line to the additional container that is embodied as a cylinder 321, the additional spring 322 does not act on a fluid with a flow connection to the absorber 20. Therefore, second additional spring 322 does not act on the vehicle body FK and the vehicle axle FA. In the switching state of the shut-off valve 324 shown in FIG. 1, the additional spring 312 and the suspension spring 10 act in parallel with each other, so that the total spring constant k.sub.G1 of the spring-absorber system of FIG. 1 results from the sum of the spring constant k.sub.T of the spring and the spring constant k.sub.31 of the first additional spring module (k.sub.n, wherein n is replaced by the designation of the acting additional spring module 31). In FIG. 1, the total spring constant thus results from the formula k.sub.G1=k.sub.T+k.sub.31. The spring constant k.sub.32 of the additional spring 322 is a multiple smaller than the spring constant k.sub.31, so that by switching the shut-off valve 324 from the shut-off position shown into a flow position that makes the connection to the absorber the total spring rate k.sub.G would essentially correspond to k.sub.T.
(7) In the spring-absorber system shown in FIG. 2, the four additional spring modules 31, 32, 33, 34 are each embodied with a shut-off valve 314, 324, 334, 344, to which a throttle valve 315, 325, 335, 345 is connected in parallel for flow purposes, so that a slow pressure equalization can occur at a high differential pressure between the additional spring modules 31, 32, 33, 34 or the absorber 20. The additional spring modules each have a cylinder 311,321, 331, 341 in which a fluid is pressurized by means of an additional spring 312, 322, 332, 342 using a respective separating piston 313, 323, 333, 343. The shut-off valves 324, 334 of the second and third additional spring modules are in their respective flow positions, so that the additional springs 322, 332 of the second and third additional spring modules 32, 33 transfer the spring force thereof by means of the fluid to the absorber 20 and thus to the vehicle body FK and the vehicle axle FA. The additional springs 322, 332 act in series with each other and in parallel with the suspension spring 10, so that the following formula results for the total spring constant k.sub.G2 of the spring-absorber system in the switching position of the shut-off valves 314, 324, 334, 344 shown in FIG. 2
(8)
(9) FIG. 3 shows an alternative embodiment to the spring-absorber system in FIG. 1, with which the first and second additional spring modules 41, 42 comprise a common cylinder 40, in which the respective additional containers that are pressurized by the additional springs 44, 45 are arranged. Of the additional spring modules 41, 42, only the second additional spring module 42 comprises a shut-off valve 46 with which the throttle valve 47 is connected in parallel. Due to the switching position of the shut-off valve 46, which is set in its flow position, the additional springs 44, 45 of the additional spring modules 41, 42 act in series with each other. Since as described in FIG. 1 one of the spring constants of the additional springs 41, 42 is very small, the additional containers of the additional spring modules 41, 42 act essentially as a compensating container for the fluid displaced by the piston rod 24 without exerting a great influence on the total spring constant k.sub.G of the spring-absorber system. The total spring constant k.sub.G of the spring-absorber system in FIG. 3 therefore corresponds essentially to the spring constant k.sub.T of the suspension spring.
(10) The implementation of the invention is not limited to the preferred embodiments indicated above. Rather, a number of variants is conceivable that make use of the presented solution even in fundamentally different designs. For example, the respective pretensioning of the additional springs could be mechanically adjustable by a respective pretensioning mechanism.
(11) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
