DE8612723U1 - Hydraulic telescopic shock absorber - Google Patents

Description

The innovation concerns hydraulic telescopic shock absorbers, in particular for the suspension of motor vehicles.

In hydraulic telescopic shock absorbers, the piston generally has Valves or other equivalent means, which the flow of the liquid between the formed by the piston The working chambers of the cylinder are intended to brake.

The use of valves of the classic design generally leads to damping characteristics in which the damping with the speed of the piston displacement in the cylinder grows. This characteristic can be acceptable if the piston of the shock absorber is pulled out, while it would, however, be very useful to increase the damping effect above a certain level Displacement speed of the piston in the compression phase to be able to reduce, because this would improve driving comfort without noticeably impairing driving behavior.

The innovation is based on the task of being as simple as possible in a shock absorber of the specified type with the help of one System to realize a damping curve that reduces the force causes when the piston has a certain displacement speed, which can be freely selected, exceeds.

With a hydraulic telescopic shock absorber with one in one Cylinder sliding piston that separates the two working chambers separates and has the usual means for limiting the flow of liquid from one chamber to the other, This object is achieved in that an additional flow connection is provided with a variable surface that connects the two working chambers and that of a closure member is controlled, which is directly dependent on the speed of movement of the piston is affected.

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Further features and advantages of the innovation result from the Claims for protection and from the following description of an exemplary embodiment, the Ί ii of the drawing is shown.

It showsi

Figure 1 is a schematic sectional view of a piston for
a shock absorber according to the innovation and

FIG. 2 shows a diagram to illustrate the different changes in the damping effect as a function of the piston speed and the size of the flow opening
with the newly designed shock absorber.

Figure 1 shows a part of a shock absorber in longitudinal section a piston 1 which, in a manner known per se, consists of a piston body 2 and two plates 3 and 4, which are held together by a nut 5 on the threaded end of a Piston rod 6 is screwed on.

The piston 1 divides a cylinder 9 into two working chambers

7 and 8 and has not shown, known means for throttling the flow of the liquid from the working chamber 7 into the Working chamber 8 during the compression phase. Other known means, also not shown, effect the braking the displacement of the piston 1 during the rebound, that is, when the liquid flows from the working chamber

8 into the working chamber 7.

To the mentioned displacement speed as a function of on To be able to change the force exerted by the piston in order to improve the driving comfort of the vehicle are in addition to the mentioned and known means have taken further precautions, which are explained below and which are the subject of the innovation. .

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A cavity 11 is incorporated into the body 2, which via a bore 12 in the plate 3 with the working chamber 7 and via a bore 13 in the plate 4 with the working chamber 8 is in connection. The cavity 12 has an almost complete one circular cross-section with a radial incision 14 for the passage of liquid.

A small piston is used to open and close the bore 12 15, which is slidably seated in the cavity Ü and is held in the closed position by a calibrated spring 16.

The explained shock absorber with the newly designed one Piston works in the following way:

a If the movement of piston 1 during the compression phase * is relatively slow, the liquid flowing from the working chamber 7 into the working chamber 8 is normally of the known means, which are usually incorporated and not shown are braked. The pressure difference between the two working chambers 7 and 8 depends on the diameter of the flow bores the known valve means. This flow loss increases in direct proportion to the increase in the displacement speed of the piston 1 and thus the force acting on it.

From a certain piston speed threshold the force of the spring 16 is overcome, so that the bore 12 j ■ is opened and the small piston 15 moves upwards, whereby it releases the radial incision 14 more and more with increasing displacement. This is how you get one substantial drop in the damping characteristics, such as results from the diagram of FIG. In this diagram, the piston speed ν is plotted on the abscissa, while the ordinate the damping properties, that is to say those on the Plunger acting force F reproduces.

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How thisir. Diagramfü shows the Verri can ngeru-ng the damping characteristics by changing the opening cross section of the recess 14 for fluid flow arbitrarily varies Werden.- a larger opening width A corresponds to a more pronounced _s sloping curve A, while decreasing a smaller opening width G in a much less Characteristic leads.

In addition, the Ströriiüngsverluste change with progressive displacement of the small piston 15 upwards, with this an ever larger passage opening in the area of the Incision 14 releases.

Claims (4)

Protection claims 1. Hydraulic telescopic shock absorber with one in a cylinder displaceably mounted piston, the two working chambers from each other separates and r. with usual means of flow limitation the liquid from one working chamber to the other, characterized by an additional one Passage (11, 14) with variable cross-section, which is able to connect the two working chambers (7, 8) to one another to connect · and for its control a closure member directly influenced by the displacement speed of the piston (1) (15) is provided. 2. Shock absorber according to claim 1, characterized in that the additional passage an almost completely circular Has cross section with a radial incision (14) in the form of a passage slot. 3. Shock absorber according to claim 2, characterized in that the radial incision (14) at the additional passage has a cross-section adapted to the desired damping. 2 - t * m 4. Shock absorber according to one of the preceding claims, characterized in that the displaceable in the additional passage Closure member (15) is acted upon by a calibrated spring (16) in the closing direction.