DE3107517A1 - Hydraulically acting shock absorber - Google Patents

Abstract

A piston (32) is displaceable in a chamber (54, 56) of a shock absorber (fig. 1) filled with a medium under the effect of a shock transmitted to the shock absorber. An upper and a lower section of the chamber are connected to one another through the piston by means of a plurality of connecting ducts (66) in the piston (32). A valve element (68) arranged in each flow duct is capable of limiting the flow of medium through the duct. It limits the flow of medium through the connecting duct (66) as a function of the piston stroke. <IMAGE>

Description

TER MEER · MÜLLER ■ STEINMEISTER; Nissan

DESCRIPTION

The invention relates to a hydraulically acting shock absorber of the type mentioned in the preamble of claim 1 Art.

A hydraulic shock absorber essentially consists of a cylinder filled with a working medium and a cylinder piston displaceable within the cylinder under the action of a shock load transmitted to the shock absorber with a damping device, which reduces the shock in the course of the piston movement via a flow restriction absorbs or dampens the medium flowing through the piston. Since in conventional shock absorbers in the 5 Working medium generated damping force from the speed depends on the piston movement in the cylinder, is inevitably on the one hand with a relatively short impact very small piston stroke, but very high piston speed, the damping force is greater than required and on the other hand with a low piston speed in connection with a very long impact the damping force is too small for effective shock absorption fail.

This effect is intended using an example of one in the wheel suspension a motor vehicle built-in conventional shock absorbers are made clear: when driving slowly a largely flat and straight road, there are only relatively minor impacts from the road to the vehicle transmitted, which only require a low damping effect. At high speed is the transmission speed But the road bumps are so high that the damping effect assumes magnitudes that are not necessary are, but degrade driving comfort. If, on the other hand, the vehicle is on a winding or very uneven surface Road driving is possible because of the relatively slow speed of shock transmission to the vehicle

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TER MEER · MÜLLER · STEINMEISTER

- 7 the shock absorption effect is insufficient.

The invention is based on the object of improving a shock absorber of the type mentioned in such a way that it not only reacts to the speed, but also to the size or length of occurring shocks.

The inventive solution to the problem posed is briefly stated in claim 1. 10

Advantageous further developments of the inventive concept are set out in subclaims.

The shock absorber according to the invention has a piston that is movable in a working medium containing inner chamber and each occupies a position that of a is dependent on the shock transmitted to the shock absorber. The piston contains at least one connection or through-flow channel for the fluid or medium as a communication path between an upper and a lower portion of the chamber with respect to the Pistons. A valve element arranged in the flow channel limits the throughput of the medium through the channel, when the piston stroke exceeds a given limit.

By limiting the cross-section of the flow duct at a piston stroke exceeding a limit value becomes an absorption or movement in the opposite direction to the piston movement Damping force generated.

Some embodiments having the features of the invention are described below with reference to a Drawing explained in more detail. Show it:

Fig. 1 is a longitudinal section through a first 5 embodiment of an invention

proper shock absorber;

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Fig. 2 is an enlarged cross-section in

Course of a line 2-2 in FIG. 1;

Figure 3 is an exploded perspective view of a piston in the joint

damper of Fig. 1;

Fig. 4 is an enlarged partial section in

Course of a plane 4-4 of FIG. 2; 10

5 is an enlarged perspective view of a valve element in the shock absorber of Fig. 1;

6 and 7 each show a graphic representation of the dependence of the passage cross section of the valve element position or the dependence of the damping force on the valve element stroke and the impact speed;

FIG. 8 shows a representation similar to FIG. 2

a modification of the first embodiment;
25th

9 and 10 each have a partial cross-section in the course

a line 9-9 or 10-10 of Fig. 8;

11 shows a graphical representation of the dependency the damping force at the

The embodiment of FIG. 8 of the stroke of the valve element;

Fig. 12 is a partially sectioned perspective view of a piston from a

second embodiment of the invention;

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Fig. 13, 14 a partial section of the piston, a and FIG. 15 is an enlarged perspective view of a valve element contained therein and a functional illustration of the valve element of the piston or shock absorber

Fig. 12;

16 shows a graphic representation of the dependence of the damping effect on the Movement distance of the valve element;

17 and 18 partial sections through modifications of the

in Fig. 12 partially shown shock absorber;
15th

19 shows a graphical illustration of the dependency of the damping force of the modification in FIG. 18 on the piston movement distance;
20th

20 shows a partial section through another

Modification of the embodiment of FIG. 12;

21 is a plan view of a valve element

as part of a shock absorbing device of the embodiment of FIG Fig. 12;

22 shows a partial section through a further one

Modification of the embodiment of FIG. 12;

FIG. 23 is a graph showing the dependency of the shock absorbing effect in FIG

Modification of FIG. 22;

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Fig. 24 is an exploded perspective view of a third embodiment of the invention;

25 shows a cross-sectional illustration of the third exemplary embodiment of a shock absorber in Fig. 24;

Fig. 26 is a partial section taken along line 26-26 of Fig. 25;

27 is a graph showing the dependency of the absorption effect of the 24 from the piston movement or velocity;

28 shows a partial cross section through a modification of the third exemplary embodiment in Fig. 24; and 20

29 shows a partial section through another

Embodiment of the invention with a valve element acting only in one piston direction.
25th

The first exemplary embodiment of a shock absorber according to the invention, shown in particular in FIGS. 1 to 5 comprises a hollow cylinder 30 and closed at its top by a cover 34 with a sealing element 36 a piston 32 which can be moved within this cylinder 30 and which, at one end formed as a threaded section 46 an outwardly leading piston rod 42 by means of a nut 48 screwed onto the threaded section is. The interior of the cylinder 30 is filled with a working medium (liquid) in order to counteract a Shock absorber acting shock an absorption or damping

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Nis'san

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to build up management skills. The piston rod 42 is through central openings 38, 40 of the cover 34 and the sealing element passed to the outside and carries at its outer end a fastening ring 44. The threaded portion 46 of the piston rod 42 is located in a central opening 33 of the piston 32. The fixed in the manner described with the piston rod 4 2 connected pistons 32 follows any movement of the piston rod.

In an annular groove 50 machined into the circumference of the piston 32, an annular groove 50 rests against the inner circumference of the cylinder 30 Sealing ring 52 inserted. The interior of the cylinder 30 is thus divided into an upper chamber 54 and a lower chamber 56 divided. In the lower chamber 56 there is a freely movable and by means of an annular seal 60 opposite the Inner circumference of the cylinder 30 sealed piston 58, which the medium located in the lower chamber 56 of a gas-filled chamber 62 separates which volume changes of the working medium infoige movements of the KoI-

20 rod 4 2 balances.

A fastening ring 64 is attached to the lower end of the cylinder 30. Both mounting rings 44 and 64 are preferred filled with vibration-damping elastic bushings. About the two fastening rings 44 and 64 is the shock absorber is fixed between two mutually movable elements during operation. When using the shock absorber In a motor vehicle chassis, the upper ring 4 4 is on one Upper link and the lower ring 64 attached to a lower link of the wheel suspension or the like. '

According to FIGS. 2 to 4, the piston 32 is composed of an upper disk 320 and a lower disk 350, of which each disk has two opposite and parallel openings 322 and 352, which are in the same alignment in the assembled state, as in FIG E ¹ Ig. 4. Any

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these openings 322 and 352 are each a narrow cylindrical Section 324 or 354, a wide cylindrical section 326 or 356 and a conical intermediate section 328 or 358 subdivided. According to FIG. 4, these two opposing pairs of openings are in alignment Through-flow channels 66 in the piston 32, on each of which an upper and a lower passage 661,662, each an upper and a lower valve seat portion 663,664 and one formed by the wide cylindrical portions 326 and 356 Valve chamber 665 are to be distinguished. A valve element which is movably arranged within this valve chamber 6 65 68 has conical end sections 70 and 71 at both ends and a middle section 73 in between several grooves 72 incorporated as passageways for the working medium are.

The valve element 68 made of a suitable material is preferably made of a synthetic resin or the like , the specific weight of which essentially corresponds to that of the working medium. A valve element made of metal would have a higher specific weight than the working medium and would therefore not easily be held exactly in the center of the valve chamber if this was not done by additional measures such as increased friction between the circumference of the valve element and the inner circumference of the throughflow channel 66 or through a support spring is brought about. A valve element 68 made of metal with a downward neutral position would not lead to serious problems for the function of the shock absorber, however, because the valve element 68 usually moves continuously up and down during the operation of the shock absorber, so that no one-sided preference for the direction of the damping of shocks will occur. A valve element made of synthetic resin has the advantage of less inertia.

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When the shock absorber is at rest (see FIG. 4), the valve elements 68 are in their neutral position, from which a stroke H is possible up and down. When the shock absorber is shortened by impact, the piston 32 reduces the volume of the lower chamber 56 and thereby builds up a pressure difference in the working medium between the chambers 54 and 56 which drives the medium under pressure via the lower passage 662 into the valve chamber 665. Accordingly, fluid flows past the valve seat section 664 into the valve chamber 665, and the valve element 68 is accordingly displaced in the direction of the upper passage 661 by the fluid pressure in the valve chamber. In the stroke range of the valve element h-, the conical end section 70 does not yet reach the lower end of the passage 661, the open cross-sectional area S ₁ (= π / 4-d ² ) of the passage 661 remains unchanged, and consequently the passage through the valve element 68 remains unchanged Piston 32 generated damping force its uniform minimum value. As soon as the valve linen t 68 exceeds this initial stroke range h- and approaches the narrow cylindrical section 324, the passage cross section of the passage 661 becomes increasingly narrower and the damping force increases accordingly, see FIG upper edge of the middle section 73 or the lower edge of the valve seat section 663, so that the open cross-sectional area of the passage 661 cannot be completely shut off, but a connection between the chambers 56 and 54 still remains.

If the shock absorber lasts longer due to external impact is and the piston 32 migrates upwards and the volume of the chamber 54 is reduced, then occurs opposite the case described above, an opposite pressure difference between the chambers 54 and 56, which the Ventiieiemente 68 can migrate downward within their flow channels 6 6. With the opposite sign,

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chen similar attenuation conditions as described above, because of the open cross-sectional area of the lower passageways 66 2 correspondingly increasingly reduced and the throughput of the working medium through the flow channels 66 accordingly is limited in order to optimally dampen the piston movement.

As can be seen from Fig. 7, is in the Durchströmkanai 66 generated damping force by the valve element movement also from the piston movement speed as with conventional shock absorbers. According to FIG. 7, in the first exemplary embodiment of the invention described above, the movement opposite to the piston movement increases Damping force as a function of the piston stroke and the piston speed. In this way, the Driving comfort of the vehicle can be improved.

In a modification of the first exemplary embodiment shown in FIGS. 8 to 10, the piston 32 has four throughflow channels 741, 742, 743 and 744 evenly distributed over its circumference, in each of which a valve element 761, 762, 763 or 764 is movably arranged, but all valve elements have a different maximum range of movement H. ₁ , H ₂ , H-. or H .. The relative dimensions between each of the throughflow channels 741 to 74 4 and the valve element 761,762,763 or 764 arranged therein are different, so that the respective conical end section or head 781,782,783 or 784 of the valve element in question is not the inner end of the respective passage can reach. The stroke ranges of the individual valve elements are graduated such that H ₁ > H ₂ > H ₃ > H ₄ and h ₁ > h ₂ > h ₃ > h applies. If the valve element 764 exceeds the height h i during a stroke of the piston of FIG. 10, its end section 784 increasingly reduces the passage cross-section of the channel 744. The damping force in the passage 764 increases.

With the stroke H. of the valve element, the damping effect according to FIG. 11 increases to A. With a stroke H-. of the valve

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ments, the damping force counteracting the piston movement in the penetration channels 743 and 744 is particularly high The damping force B of the shock absorber is the sum of all forces in the penetration channels 743 and 744. On these Way, the damping force of the shock absorber increases gradually. In this variant embodiment runs the change in the damping force is moderate, the occupants of the vehicle are not affected by a strongly increasing damping effect annoyed in the suspension.

In a second embodiment shown in FIGS a shock absorber according to the invention is the an upper disk 110 and a lower disk 130 existing piston 100 in the area of its central opening 104 on the threaded portion 102 of a piston rod 103 by a Nut 104 attached.

There is a step-shaped opening in the two disks 110, 130 111, 131 incorporated with a circular cross-section in each plane. The breakthrough sections lying in the same alignment in the two disks 110 and 130 each have a section with a small diameter 112, 132 and a section large diameter 113,133, the last of which are listed larger sections form a valve chamber 105 in the piston 100 and the smaller sections 112,132 than Inlet paths of communication between the chambers 54, 56 and the valve chamber 105 are used.

In the valve chamber 105 there is a valve element 106 in the form of a valve element which can be elastically deformed by the fluid flow in the chamber simple thin plate, preferably a steel leaf spring, with the inner circumference of its central opening is attached to the inner vertical wall 107 of the valve chamber 105 that the valve element 106 resides in its neutral position at a medium altitude in the valve chamber. Instead of the inner circumferential

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wall 107, as shown in Fig. 13, the valve element also be fastened at any other point on a vertically extending wall of the valve chamber 105.

A cutout 108 recognizable in FIG. 14 at the free ends of the valve element 106 prevents it from being complete Closing the inlet paths 112, 132 of the piston opening, when the valve element shown in FIG. 15 is deformed. Instead of such cutouts 108, this valve element 106 also have one or more breakthroughs in suitable locations, which completely shut off the inlet paths 112 and 132 prevent. For example, according to FIG. 17 two stops 109 may be present in order to limit the deflections of the valve element.

If the shock absorber becomes longer in operation and the Piston is drawn into the upper chamber 54, the pressure of the medium increases therein more than in the lower chamber. The pressure difference built up in this way leaves the fluid or working medium flow from the upper chamber through the inlet path 112 of the piston 100 into its valve chamber 105, and in the process, the valve element 106 is displaced downwards and thereby changes the cross-sections on the inner walls of the Inlet paths 112,132. In the position indicated in FIG B, there is still no significant change in the cross-sectional area of the inlet path, but in position C (Fig. 15) the valve element 106 limits the free cross-sectional area of the intake path 132 is considerable, and the damping force increases sharply as shown in FIG is.

In the modification of the second shown in FIG In the exemplary embodiment of the invention, the lower disk 130 is significantly thicker than the upper disk 110 / and accordingly the valve element 106 is located at the interface between the two disks in the upper third

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the height of the valve chamber 105. Its height distance T ₁ from the lower end of the inlet path 112 is smaller than its distance T 1 from the upper end of the lower inlet path 132. Consequently, the valve element 106 already becomes the deflection position B (FIG. 15) when the shock absorber is shortened after a relatively short piston stroke, but when the shock absorber is lengthened, the downward deflection position B can only be reached with a relatively long piston stroke. Consequently, this embodiment of the invention generates a different damping force when the shock absorber is shortened than when it is lengthened, see FIG. 19. Such a shock absorber with different damping forces in both directions of action is particularly suitable for the chassis of motor vehicles.

The same effect can also be achieved with the modification shown in FIG. 20, in which the valve element 106 Stiffened on both sides by a leaf spring 150 or 151 is to limit the deflection upwards and downwards in a targeted manner. The leaf springs 150 and 151 have different ones Elasticity values, so that the deflection of the valve element 106 upwards under the influence of the flowing medium is different turns out to be down.

The valve element 106 designed as a leaf spring in FIG.

14 has two tongue sections extending radially from a circular central section 1061 with a central bore 1063 1062. The modification shown in Fig. 21 includes four radially extending movable tongue sections 1062, some of which are shown in phantom. The valve element 106 is opposite through the central bore 1063 centered on the inner wall 107 of the piston 100 and fastened by a welded connection or other measures.

In another modification of the second exemplary embodiment shown in FIG. 22, the one designated by 100 has The piston of the shock absorber has a smaller valve chamber 1051 and

TER MEER · MÜLLER · STEINMEISTER ''"'" Nissan.

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a larger valve chamber 1052. As with the one in FIG The illustrated embodiment is here the valve element 106 in the middle height position on the inner circumference of the Valve chambers 1051 and 1052 attached. Because of the different valve chamber sizes, the one in FIG. 15 Deformation of the valve element 106 shown under position B in each case with a different piston or valve element stroke instead, so that according to FIG. Valve element stroke dependent damping force step by step increases depending on the size or length of the joint.

The piston 200 shown in FIGS. 24 to 26 of a shock absorber forming a third embodiment of the invention is attached to the lower end of the piston rod 210 by means of a nut 211 and has a special feature Overpressure or relief valves 230 and 232, which according to FIGS. 24 and 25 are diametrically opposite and in the circumferential direction are arranged offset with respect to a throughflow channel 201. For each relief valve there is one Through hole 233 or 234 and one each on the top and bottom of the piston 200 through a disk 240 or 241 held leaf spring washer 235 or 236. In the area of the mouth of each through-flow channel 201, each has Leaf spring washers each have an opening 237, as FIG. 24 shows. In the piston 200 are at the upper end of the through hole 233 a cutout 238 and at the lower end of the Through hole 234 a cutout 239 incorporated.

A valve element 20 2 designed as an elastic leaf spring carries conically on both surfaces of its free ends formed lugs 203 and 204, which conical sections 205 and 206 of the flow channels 201 are opposite, the 26 are located between the inner valve chamber 209 of the piston and passage paths 207 and 208, respectively. if the working medium flows through the flow channel 201,

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If the valve element 202 is deformed, the lugs 203, 204 penetrate the conical sections 205 and 206, limit the flow cross-section and thus increase the damping force in connection with the liquid flow. If a pressure has built up in one of the chambers that exceeds a predetermined limit value, then this will be the case Relief valve 230 or 232 in question is effective, opens and reduces the overpressure.

When the shock absorber is compressed, the pressure in the one below the piston 200 increases Chamber, and the pressure medium located in the cutout 2 39 deforms the leaf spring washer 235 so that they the Through hole 234 opens.

According to the invention, the relief valve is not limited to the description given here, but rather are various Modifications or other shapes possible. A corresponding modification is shown in FIG. 28.

The relief valve 250 contained in Fig. 28 is located in a bore 251 of the piston 200, which is through a upper bore 252 with the upper chamber and through a lower bore 253 with the lower chamber of the shock absorber connected is. Furthermore, the middle bore 251 with both shock absorber chambers is through one outlet channel each 254 or 255 connected. A cylindrical valve element 256 movably arranged in the central bore 251 is so loaded from both sides by essentially equally strong helical compression springs 257 and 258 that it is normally resides in a neutral position where the communication between the bore 251 and the outlet channels 254,255 is blocked. If the pressure in one medium chamber exceeds the spring force, it will Valve element 256 shifted on one side by the pressure until a connection between the pipe 251 and the outlet

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laßkanäien 254 and 255 exists. If consequently the medium pressure exceeds a limit value corresponding to the force of springs 257 and 258, the relief valve speaks 250 and ensures pressure equalization. ·

In this embodiment of the invention changes the damping effect of the shock absorber with the speed of the piston movement, as shown in FIG.

The exemplary embodiments described above are applications of the invention to single-cylinder double-acting shock absorber types. In addition, the invention is can also be used for single-acting double cylinder types, as indicated in the example shown in FIG is. FIG. 29 shows an example of a valve construction which is inserted into the piston or the bottom valve of a single-acting Double cylinder shock absorber is installed. A Valve element 270 in FIG. 29 has a conically shaped head 271, a plate section 272 with a larger one Diameter and a cylindrical extension 273 with a smaller diameter. One of this valve element 270 is movable The receiving valve chamber 274 contains a conical valve seat section 275 and stands on the one hand with the upper chamber of the shock absorber via a channel 276 and with the lower chamber via a channel 277 in Link. In the plate section 272 of the valve element 270, several perpendicular grooves 278 are formed, through which the medium can flow. The valve in Fig. 29 only dampens a downward piston movement, when it moves up by itself.

Of course, the invention is not restricted to the exemplary embodiments described above, but also extends to all possible modifications. All on ? ^The shock absorbers on the market can be converted according to the invention.

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Claims (2)

PATENT LAWYERS 1107517 TER MEER - MÜLLER - STEINMEISTER Professors before the European Patent Office approved by the European Palentami - Mandatalre »agrees pres I'Office europeen des brevets Dipl.-Chem. Dr. N. ter Meer Dipl.-Ing. H. Steinmeister Dipl.-Ing. FE Müller ο "[,"".," Ι, -, Triftstrasse 4, S.ekerwall 7, D-8000 MUNICH 22 D-4800 BIELEFELD 1 WG0467 / 269 (3) / SO
St / Gt / ri 2 Feb 7 NISSAN MOTOR COMPANY, LTD. No. 2, Takara-cho, Kanagawa-ku, Yokohama-shi / Kanagawa-ken, Japan HYDRAULIC SHOCK ABSORBER PRIORITY: February 27, 1980, Japan, No. 55-23567 PATENT CLAIMS λ .J Hydraulically acting shock absorber with a hollow cylinder containing a working fluid or medium and a piston arranged in the cylinder, which is moved along the inner surface of the cylinder under the action of a shock transmitted to the shock absorber and the interior of the cylinder into a first and a second chamber subdivided, characterized in that the piston (32; 100) has at least one fluid connection channel (eg 66) via which the two chambers (54, 56) are connected to one another; and that in the connecting channel a valve element (68; 106) limiting the flow of the medium through the channel is arranged, which valve element 130Q52 / 0648 TER MEER · MÜLLER · STEiNMEISTER Depending on the piston stroke, the piston movement is variable dampening force generated. 2. Shock absorber according to claim 1, characterized in that the fluid connection channel · a valve element (68) containing valve chamber (665), each via a passage (661,662) with the first or second Chamber (54, -56) is connected, and that the valve element so relative to the opposite ends of these passages is movable that their passage cross-section as a function is limited by a piston stroke exceeding the limit value set at the Geigebenen. 3. Shock absorber according to claim 2, characterized in that the valve element (68) is in the valve chamber is the driving moving body, which has a conically shaped head (70, 71) at each of its two ends, in order to increasingly reduce the passage cross-section of the connecting channel, and that the valve element so at a distance from the inner ends of the passageways that the distance between the top of the head and the inner Passage ends corresponds to the given limit value of the piston movement. 4. Shock absorber according to claim 2, characterized in that the valve element is an elastic plane Body (106) and the inner ends of the passages (112,132) is opposite so that the given at a When the piston stroke exceeds the limit value, the open passage cross-section of the passage paths is increasingly reduced (Fig. 15). 5. Shock absorber according to one of claims 1 to 4, characterized in that the piston (32) has several Connection channels each with a valve element arranged therein 130052/0648 TER MEER · MÜLLER · STEINMEISTER 31Q7517 ment, and that there are differences between the valve elements and their connecting channels, each of which has a flow-limiting effect at correspondingly different piston stroke limit values (FIG. 8).
5 6. Shock absorber according to one of claims 1 to 4, characterized in that the piston (200) further a relief device (230,232), soft when a given pressure value is exceeded with the can yield to this pressurized medium. 7. Shock absorber according to claim 6, characterized in that the relief device has a first opening (233,234) connecting to the second chamber and an elastic closure element (235,236) which is elastically biased into a closed position blocking the end of the opening and when the pressure of the medium exceeds the predetermined limit value, the end of the opening releases, includes (Fig. 24). 8. Shock absorber according to claim 6, characterized in that the relief device is a first through opening (251) connecting to the second chamber and a valve element arranged displaceably therein (256), which in its neutral position has a through opening with the outlet channel connecting to the first or second chamber closes, but through one set via one Value increasing pressure of the medium is moved, includes (Fig. 28). 9. Shock absorber according to claim 2, characterized in that the piston (32; 100) with a relative to the cylinder (30) movable upper part (42,44) is connected; and that in the valve chamber (665; 105) of the fluid connection channel contained valve element (68; 106) so relative to the inner ends of the two-sided passage ways 130052/0648 TER MEER · MÜLLER ■ STEINMEISTER (e.g. 661,662) is movable that in this area the free through-flow cross-sectional area limited. 10. Shock absorber according to claim 1, the cylinder of which is connected to a lower part and the piston of which is connected to an upper part of a vehicle chassis, characterized in that
- In the piston at least one fluid connection channel (eg 66) connecting the first with the second chamber (54, 56) with a valve chamber contained therein, which communicates with the first chamber via a first passage and with the second chamber via a second passage is, is incorporated, and that - A valve element (e.g. 68) is arranged in the valve chamber, which is inserted therein as a function of the piston stroke so relative to the inner ends of the first and second passageway is displaced that there is thereby the free Reduced passage cross-section at the inner end of the first and second passage and by a corresponding Limitation of the fluid or working medium throughput absorbs the energy of a shock transmitted to the shock absorber. 11. Shock absorber according to claim 9 or 10, characterized in that the valve element (e.g. 106) normally occupies a neutral position in which it is from the two inner ends of the first and second passageways maintains a distance and there is a margin of valve movement without changing the flow cross-section. 12. Shock absorber according to claim 9 or 10, characterized in that the valve element is a moving body is made of a synthetic resin which has essentially the same specific weight as the working medium and its conical upper and lower ends (70, 130052/0648 TER MEER · MÜLLER - STEINMEISTER 71) are designed in such a way that, depending on a change in the specified piston stroke path, the reduce the open cross-sectional area of the inner ends of the first and second passageways (e.g. 661,662), respectively. 5 13. Shock absorber according to claim 9 or 10, characterized in that the valve element has a deflectable Leaf spring (e.g. 106), which is located inside the valve chamber and depending on a change of the predetermined piston stroke, the open cross-sectional area of the inner ends of the first and second increases Passage limited. 1 30052/0848