Patent ID: 12215755

DETAILED DESCRIPTION

FIG.1shows a damping valve device1for a vibration damper3of arbitrary construction, illustrated only in part. The damping valve device1comprises a first damping valve5having a damping valve body embodied as a piston7, which is secured on a piston rod9.

The damping valve body7divides a cylinder11of the vibration damper3into a working chamber13on a piston-rod side and a working chamber15on the side remote from the piston rod9, both of said chambers13,15being filled with damping medium. Through channels17,19for respective through flow directions are formed on different pitch circles in the damping valve body7. The configuration of the through channels17,19should be regarded as purely illustrative. An outlet side of the through channels17;19is covered at least partially by at least one valve disk21;23.

In addition, the vibration damper3has a tension stop25, which comes to rest against a stop surface of the cylinder, e.g. a piston rod guide27, from a defined extension movement of the piston rod9onward.

The tension stop25comprises a tension stop disk as a valve support29, which is fixed directly on the piston rod by a positive joint. By way of example, an annular elastomer element31, which is held by a slight radial prestress even in the case of a vibrational movement of the piston rod9, is placed on an upper side of the valve support29. Starting from the point of stop contact with the stop surface, the elastomer element31acts as an additional supporting spring.

The support29has an encircling groove33, in which a valve body35of variable diameter is guided. This valve body35can be expanded in diameter and forms one component of a restriction37as part of the damping valve device1. With the inner wall39of the cylinder11, the valve body35forms the restriction37, wherein the inner wall39forms a flow guiding surface. In principle, the disclosure can also be formed in a support disk that is independent of the tension stop.

On the outside, the valve body35carries a return spring41, e.g. in the form of a retaining rind. This return spring41optionally also performs the function of an expansion limiter for the valve body35.

At a piston rod speed in a first operating range, e.g. less than 1 m/s, the restriction37is fully open. The damping force is then produced exclusively by the through channels17;19in conjunction with the valve disks21;23. When there is a flow toward the valve disks21;23, the valve disks21;23rise from their valve seating surface47;49. The lifting movement is in each case limited by a supporting disk51;53.

In a second operating range with a piston rod speed which is greater than the limit speed of the first operating range, i.e. greater than the 1 m/s indicated by way of example, the valve body35moves into a restricting position and, in the process, performs a closing movement in the direction of the flow guiding surface39. Owing to the high speed of flow of the damping medium in the restriction37shaped as an annular gap, a reduced pressure is formed, leading to radial expansion of the valve body35. However, to ensure that there is no possibility of blockage of the restriction37, the defined minimum passage cross section is maintained by the return spring41, or the valve body has external profiling which, together with the flow guiding surface39, defines the minimum passage cross section.

FIG.2shows a plan view of an optional valve body35from the cross section through the vibration damper3shown inFIG.1. The valve support29, the limiting ring41and the piston rod9have been omitted from the illustration for reasons of clarity. It can be seen that the valve body35has a transverse gap55, which reduces the pressure force required for the radial expansion movement of the valve body35. The valve body35is illustrated in the passage position at a minimum speed of flow. Consequently, the passage cross section57is the maximum. The passage cross section57is defined by the inner wall39of the cylinder11and the outer lateral surface45of the valve body35.

The valve body35has a profile59which limits the annular cross section between the valve body35and the inner wall39of the cylinder11. In this graphical illustration, the limiting profile59is embodied as a single radial projection on the lateral surface45. This gives rise to a c-shaped restriction cross section57. Between the cam-like projection59and the inner wall39there is a restriction cross section61of significantly reduced width which is maintained even in the case of a maximum expansion movement of the valve body35. Here, the radial projection59or limitation is dimensioned in such a way that it affects a damping effect only in the operating range of the restriction37(FIG.1). Owing to the relatively large circumferential extent of the radial profile59, it may be possible to increase the clearance with respect to the lateral surface45of the valve body35outside the radial profile59.

Furthermore,FIG.2shows that the valve body35comprises at least two limbs63;65, which are mounted in such a way as to be movable about a pivot bearing67. This feature is independent of the radial projection59but the two features complement one another in an advantageous manner inasmuch as the limiting profile59forms a part, e.g. a bearing pin69, of the pivot bearing67.

In this exemplary arrangement, the limbs63;65overlap in the circumferential direction, and the pivot bearing67is formed in the region of overlap. In the region of the transverse gap55too, there is an overlap between the two limbs63;65in order to minimize a damaging leakage cross section. AsFIG.1shows, the valve support29has two receiving openings73, which receive the bearing pin69. The receiving openings73in the valve support29can be embodied as simple through holes, for example. The same applies to the bearing openings75;77. To provide a certain play within the pivot bearing, however, it is also possible to provide for one bearing opening75;77to be embodied as a slot in the circumferential direction of the limb.

When the restriction is activated, i.e. there is a correspondingly high speed of flow in the restriction cross section57, the two limbs63;65of the valve body perform a radial pivoting movement about the pivot bearing67in the direction of the inner wall of the cylinder11. If there is full-surface contact of the limbs63;65, the restriction cross section61is still open and then determines the damping effect.

FIG.3is limited to a cross section through the valve support29in the region of the restriction37. In this an enlarged view, it can be seen that the restriction37has a damping device79, which acts counter to the closing movement of the valve body35and hence controls the overall behavior of the restriction37.

In this exemplary embodiment, the damping device79, which is formed by at least one elastomer body81, is supported on the valve support29. For this purpose, the valve support29has an encircling or, alternatively, segmented web83, into which the at least one elastomer body79is fitted. Between the valve body35and the elastomer body81there is a radial clearance, thus ensuring that the speed of expansion and thus of response of the valve body35in a first actuating travel range is controlled by the pressures or pressure forces in a pressure chamber85and within the restriction37and by the force of the return spring41. The pressure chamber85is bounded by an inner lateral surface87of the valve body35, a groove bottom surface89and groove side walls91;93of the valve support29. Damping medium flows into the pressure chamber85via an inflow opening95, and flows back out via an outflow channel97. The cross section ratio of the inflow channel95to the outflow channel97affects the pressure buildup in the pressure chamber85. As soon as the valve body has completed a free travel99by way of its radial expansion movement and is resting against the elastomer body81, the elastomer body81exerts an additional spring force, on the one hand, and also a damping force counter to the expansion movement of the valve body35. As a result, the expansion movement of the valve body in the direction of the flow guiding surface39on the cylinder11is slowed down.

By way of example,FIG.2depicts two damping devices, which have a different free travel with respect to the limbs63;65. Thus, the damping devices79are effective at different diameter sizes of the valve body35. By way of the number and the associated free travels99, additional parameters are available for setting the restriction37and thus the entire damping valve device1,

FIG.4shows an embodiment of the restriction37based onFIG.3, in which the damping device79of the restriction37becomes effective already in the case of an expansion movement starting from a home position with a minimum diameter of the valve body35. In this case, provision can additionally be made for the elastomer body81to rest only against the valve body35or already to have a significant prestress, which takes effect as a counterforce acting on the expansion movement.

In contrast to the exemplary arrangement shown inFIG.3, the damping device79shown inFIG.5is supported in a cap101separate from the valve support29. This cap101can be used as an option and offers the advantage that the valve support29does not have a web83to close the annular groove33, and therefore production of the valve support29is simpler. In the exemplary arrangement depicted inFIG.5, the cap101is centered on a shoulder of a top side of the valve support29and can simply be held by an interference fit since no significant axial forces arise.

In the exemplary arrangements shown inFIGS.3and4, the flexing work on the elastomer bodies is exploited for damping.FIG.6shows a variant in which the damping device additionally has hydraulic damping. For this purpose, an elastomer body81based on the construction principle shown inFIG.3is embodied as a hollow body that can be filled with damping medium and at least partially emptied via an opening103. The opening103represents a restrictor via which a damping medium volume105is displaced from the hollow body by the expanding valve body35. The hydraulic damping offers the further advantage of a speed-dependent effect of the damping device, i.e. when there is a relatively rapid expansion movement of the valve body35, the damping device79also develops a higher damping force acting counter to it. In a return movement, the elastomer body81relaxes again, as a result of which the hollow body fills with damping medium via the opening103.

FIG.7illustrates a restriction37having a valve support29which likewise has a hydraulic damping device79, in which the valve body35and the valve support29form a pressure chamber107that is compressed during an expansion movement of the valve body. For this purpose, the pressure chamber107is bounded by a top side109of the valve body and a section of a groove side wall of the annular groove33. Respective annular webs111;113, which are also formed by a separate seal, are arranged on the top side109and on the groove side wall93, respectively. The annular web111on the top side109extends with the clearance radially on the inside of the annular web113of the groove side wall93. This variant is exclusively a hydraulically acting damping device79. A gap115between the annular webs111;113and the opposite wall regions or, alternatively, a separate restriction opening117(shown in phantom) in the valve support29can be used for dimensioning the restricting effect.

FIG.8describes a restriction37in which the valve support29has the hydraulic damping device having at least one pressure chamber107which is filled with damping medium and in which a displacement body119controlled by the valve body35performs a working movement. Here, the pressure chamber107is formed in the web83corresponding toFIG.2or in a cap101as perFIG.4. No changes have to be made to the valve body35as compared with a conventional valve body35.

A pin-shaped component, which enters the pressure chamber107and, in the process, displaces damping medium via the restriction opening117, is used as a displacement body119. A return spring121ensures that the displacement body119performs a return movement into an initial position. Here too, there is the possibility of a free travel design in which the displacement takes effect even in the home position of the valve body35. The return spring121can be dimensioned in such a way that only the return movement of the displacement body119is ensured, but it is also possible to assist the return spring41with a higher spring force.

In the embodiment of the damping device79shown inFIG.9, this device has been arranged in the valve body35, i.e. the pressure chamber107is formed by the valve body35. Here too, a restriction opening117in the valve body35is used to generate the damping force. In this case too, the cap101serves for simplicity of assembly. In principle, the valve support29too can be split axially with an upper part and a lower part. In other respects, the principle of action corresponds to the embodiment shown inFIG.8.

FIG.10shows a variant of a hydraulic damping device79in which the displacement body119is embodied as a connecting rod which passes radially through the valve body35and is mounted on the valve support29. In the graphical illustration, the annular gap between the displacement body119and a wall of a stepped opening forming the pressure chamber serves as a restriction opening, in which the displacement body119is arranged. A seal123is responsible for sealing the pressure chamber107of the damping device79with respect to the pressure chamber85radially to the inside of the valve body35.

By virtue of its mounting, the displacement body119can have a certain angular mobility in order to avoid hindering the expansion movement of the valve body35. A return spring for the damping device79is not necessary since the return spring41of the valve body35ensures return of the displacement body119by way of the movement of the valve body35relative to the valve support29.

FIG.11shows the influence of the damping device79on the damping force behavior of the restriction37. Damping force characteristic “1” describes the damping force behavior of the damping valve5without the restriction37. The other extreme is described by damping force characteristic “2”, which represents a restriction37without a damping device79. As soon as a threshold for the volume flow Q has been reached and Δp occurs at the restriction37, the restriction37comes into effect with a very progressive damping force rise, which is optionally flattened again by means of a pressure limiting valve.

By means of a damping device79which has a free travel99, it is possible to achieve a comfort-enhancing rounding of the damping force characteristic in accordance with damping force characteristic “3”. In the case of a damping device79which is not provided with a free travel99, the damping force follows damping force characteristic “4”. This damping force curve is significantly shallower. A displacement of the damping force characteristic “4” is achieved if the damping device79operates with a certain preload or prestress, that is to say not only takes effect but already acts with a damping force even at a minimum diameter of the valve body35. An illustrative damping force characteristic “5” represents this principle of action.