DE3532293A1 - VIBRATION DAMPER WITH VARIABLE DAMPING FORCE - Google Patents

Description

The invention relates to a vibration damper with a variable Damping force for vehicles according to the preamble of claim 1.

Such a vibration damper is known from DE-PS 15 05 522 known, the bypass channel through throttle openings in the Kol ben rod is formed by one in the central bore of the Piston rod located spool more or less ver are closable and thereby the degree of damping for the train and Pressure damping is affected in the same way. The Change damping force detection only in the lower speed range different. Be over the entire speed range Influence of the damping force characteristic cannot be realized the; there is also a different adjustment of the identifier not possible for the rebound and compression stage.

A different change in damping force for tension and compression level is for a vibration damper according to DE-OS 34 38 467 shown, with a cross-section variable bypass a check valve is combined. This results in an un Different bypass cross-sections for the direction of pull and push, whereby a different identification change in the un lower speed range of the piston movement is made possible but not for the higher speed range. The construction wall of such a construction is due to the large number of components required for damping force adjustment high and with egg ner complicated assembly. Accordingly, one  such construction very expensive to manufacture and claimed also a relatively large amount of space in the axial direction, what has a shorter stroke for the piston rod movement.

Furthermore, DE-OS 21 19 531 a vibration damper knows which two damping valve systems are connected in series points, which are combined with a lockable channel, whereby only a damping valve system can be bridged. For optional Control of one or the other valve system or their Rei Switching is provided by DE-PatAnm No. P 34 46 133.7 suggest doing this through a controllable bypass. The Construction effort of such a damping force adjustment is high and he requires a considerable amount of space.

The object of the present invention is a vibration damper with adjustable damping force to create the one under Different levels of adjustment of the damping force over the entire Speed range for tension and compression damping with simp Chen means high and with a simple structure Has functional reliability, takes up little space and one easy assembly guaranteed.

This object is achieved in that one of the Spring-loaded bypass damper assigned to pressure damping parallel to the damping valve assigned to the pressure direction is arranged and in the direction of flow that which acts as a secondary throttle, cross section changeable channel is connected upstream. The pa Bypass steam valve arranged parallel to the steam valve enables egg ne adjustable pressure over the entire speed range damping, the adjustment mechanism is very simple in construction is, has a high level of functional reliability and the bypass damping valve itself only from a valve body and a valve spring exists, which ensures easy assembly. Correspond chend the desired pressure damping change can be done by simple Choice of valve spring or by changing its preload Desired pressure damping curve over the entire speed speed range can be obtained, such a bypass valve egg takes up little space and enables easy assembly light.  

In a further embodiment of the invention, the bypass damping valve in an axial bore of the piston rod receiving the piston arranged in a pin. This results in a particularly favorable one Construction, because the bypass damping valve does not require any additional space in the axial direction of the unit is required. The Valve body itself is bowl according to a feature of the invention shaped, the rim of the cup for the contact surface Bypass valve spring forms. Such a valve body is before preferably designed as a sheet metal part. It stands out good guidance, light weight and very good dimensionally stable.

A very advantageous embodiment is characterized by this receive that the bypass damping valve associated with the pressure damping with a damping force adjustment acting on the train damping is combined. Accordingly, such pressure damping is oh ne further with known possible devices for adjustment the train damping can be combined. It is particularly advantageous Combine with a train damping, the Ver position via a switchable, acted upon, on the train damping valve acting surface takes place.

A very simple change in the preload of the bypass valve spring is achieved according to the invention in that this is from an axial slide is changeable and this axial slide to the cross Sectional change of the bypass channel is arranged. This dop The peel function of the axial slide thus makes it possible to use it Longitudinal displacement of the bypass damper valve spring stronger preload, which dampens the proportion of spring-loaded bypass valves in the pressure damping increases more.

In a further embodiment of the invention, the bypass valve body via a pre-opening cross acting in the pull and push direction cut open. This will make a simple pre-opening change achieved via the switchable bypass.

Especially for single-tube vibration dampers, in which the in the piston rod arranged radial bores the piston rods seal must not run over, will be an extremely short overall height  created for the bypass device according to the invention in that at least one radial bore of the bypass channel with one in the col ben arranged radial channel interacts.

Using the embodiments shown in the drawing the invention is explained in more detail below. It shows:

Figure 1 shows an embodiment of the vibration damper according to the invention in longitudinal section.

Fig. 2 corresponds to the piston section of Fig. 1 in an enlarged representation;

Fig. 3 shows the piston. Fig. 2 seen from below;

A piston portion in longitudinal section, the piston being provided for a single-tube vibration damper Fig. 4;

Fig. 5 the piston gem. Fig. 4 in a view from below;

Fig. 6 shows an embodiment in which the cross-sectional radial bore of the bypass channel opens into a radial channel arranged in the piston;

Fig. 7 shows an embodiment in which an axial slide serves to change the bias of the bypass valve spring;

Fig. 8 shows the embodiment shown in Fig. 7 with increased voltage before the bypass valve spring and reduced cross section of the bypass channel.

The vibration damper acc. Fig. 1 has a cylinder 1 which is clamped concentrically in a container 2 by means of a piston rod guide 3 and a bottom valve 5 . In the piston rod guide 3 , a hollow piston rod 6 is guided and sealed by a piston rod seal 4 to the outside. The cylinder inner end of the piston rod 6 carries a piston 7 , which separates a working space 8 above the piston from a working space 9 below half of the piston. Via the bottom valve 5 , the working space 9 is connected to a compensation space 10 , which is arranged between the cylinder 1 and the container 2 , in connection. The piston 7 is provided with passage openings associated with the rebound and compression stages, which are covered by corresponding damping valves. Here, the acted upon by a valve spring 12 is Dämpfven til associated with 11 of the rebound, while the stationary damping valve be made of spring washers 18 serves the compression damping. In the bottom valve 5 , a further, the compression damping valve and a check valve for the rebound is provided. In the piston rod 6 , a bypass consisting essentially of radial bores 15 and an axial bore 17 is provided, the Ra dial bores 15 being cross-sectional changeable by a slide 16 . The damping valve 11 , which is responsive to the rebound stage, is assigned pressure chambers 13 , which open into the axial bore 17 and form additional pressurized surfaces for the damping valve 11 . Parallel to the in response to the retraction of the piston rod GE 6 responsive damping valve 18 of the piston 7 is a bypass valve body 20 and a bypass valve spring 19 bypass damper valve is arranged. Figs. 2 and 3, the before-described piston arrangement and configuration with the damping force adjusting device in an enlarged view, wherein the previously named parts are given the same reference numerals. In the figures, the bypass radial bore 15 is shown completely open by the slide 16 , so that when the piston rod 6 extends, the damping liquid acts on the damping valve 11 via the piston channels 21 assigned to the train damping. At the same time, damping fluid passes from the working space 8 via the radial bore 15 and the axial bore 17 into each pressure space 13 , the surfaces 14 also being pressurized. The caused by the extension movement of the piston rod 6 pressure increase in the damping fluid in the working chamber 8 causes that the damping valve 11 is pressurized both via the piston channels 21 associated with the damping and the pressure chambers 13 and this pressure force acts against the force of the valve spring 12 . This acting on the damping valve 11 liquid pressure force is, due to the pressure spaces 13 formed by the pressure-loaded surfaces 14 , larger when the bypass cross section is open, so that a lower damping effect is achieved. When the radial bores 15 are closed by the slide 16, only the liquid pressure in the channels 21 acts on the damping valve 11 , which corresponds to a harder setting.

In the pressure stage, ie when the piston rod 6 is pushed into the cylinder 1, the damping valve 18 of the piston 7 assigned to the pressure damping acts when the radial bores 15 are closed, with damping fluid flowing from the working space 9 through the bores 22 and the open valve cross section into the working space 8 . Another damping valve connected in series and assigned to the pressure damping is provided in the bottom valve 5 . When the Ra dial bore 15 is open, the bypass valve body 20 acted upon by the bypass valve spring 19 acts as a bypass damping valve arranged parallel to the damping valve 18 , the damping liquid from the working chamber 9 via this bypass damping valve into the axial bore 17 of the piston rod pin 23 and from there via the radial bores 15 into the working chamber 8 flows. Thus, when the radial bores 15 are open, a softer piston pressure damping is achieved by the bypass damper valve, whereby the spring-loaded bypass damper valve 19 can be made very variable by the strength and preload of the bypass valve spring 19 . The pressure-side arrangement of such a bypass damping valve makes it possible to set the course of the pressure detection of the damper with regard to the driving comfort and the driving behavior of a vehicle to the desired pressure damping values. Depending on the position of the slide 16 to the radial bore 15 , the spring-loaded bypass valve body 20 takes over a corresponding proportion of the pressure output of the piston pressure damper. If the slide 16 closes the radial bores 15 continuously, then only the damping valve 18 acts for the piston pressure damping, as a result of which the highest pressure damping is achieved.

In Figs. 4 and 5, a piston is a single-tube damper shown oscillations supply 25, which is a of the rebound damping consist assigned damping valve 26 from the valve discs and a flat optionally having damping of valve discs formed damping valve 27 for the pressure. This piston 25 is associated with the tensile damping associated piston channels 30 and channels 31 for pressure damping with Kolbenka. In addition, the radial bores 15 are connected via the axial bore 17 to pressure chambers 28 , which form pressurized surface 29 for the damping valve 26 . The bypass valve spring 19 acted upon by bypass valve body 20 is provided with egg nem pre-opening cross-section 32 which is effective when the Ra dial bores 15 are open in the pulling and pushing directions. Here too, the soft damping force setting is achieved when the radial bores 15 are fully open, the damping valve 26 being acted upon in the pulling direction by the piston channels 30 and the pressurized surfaces 29 formed by the pressure chambers 28 . By rotating the slide 16 , the radial bores 15 experience a reduction in cross-section, so that, as a result of pre-throttling, the full damping pressure no longer acts on the pressurized surfaces 29, and therefore a damping pressure which starts between a certain piston speed and is between a maximum and a minimum predetermined ID. When the radial bores are closed, the maximum identifier is reached because only the piston channels 30 act on the damping valve 26 . Also arranged in the bypass valve body 20 pre-opening cross-section 32 is ineffective when Ra dial bores 15 closed, while this with open radial bores 15 in both directions of movement, that is, for the tension and pressure damping, acts. The maximum pressure damping is also achieved when the radial bores 15 are closed, the piston channels 31 acting on the damping valve 27 . When open Ra dial bores 15 acts parallel to the damping valves 27, the bypass valve body 19 , the bypass valve body 20 and the Voröff voltage cross section 32 existing bypass damping valve. In this case the minimum pressure damping identifier is then available. This pressure damping identifier can be varied by appropriate choice of the bypass valve spring and its pretension and by the size of the opening 32 Voröff opening.

The embodiment acc. Fig. 6 differs from that of FIGS. 1 to 3 essentially in that each radial bore 15 which can be closed by the slide 16 opens into a radial channel 33 of the piston 7 . In operation, this form of implementation also corresponds to that described in FIGS. 1 to 3.

In Figs. 7 and 8 is shown an embodiment in wel cher the associated one of the pressure damping Bypaßdämpfventil tilplatte a Ven 37 which is beat by the Bypaßventilfeder 19 beauf while it Bypaßventilfeder 19 on the other hand is supported on a spring plate 36. In the hollow piston rod 6 there is a pressurized axial slide 34 which , depending on the pressure acting on it, is axially displaceable against the force of a spring 38 and acts on the spring plate 36 with an extension 35 and this axial slide 34 serves at the same time to change the cross section of the radial bores 15 . In Fig. 7, these radial bores 15 are fully open and the spring plate 36 rests with the upper end face on a corresponding stop surface. This position corresponds to the minimum characteristic of the pressure damping force. By pressure on the axial slide 34 this is moved against the force of the spring 38 to th th, so that the neck 35 takes the spring plate 36 and thereby biases the bypass valve spring 19 . From a certain th approach of the axial slide 34 , the bypass radial bores 15 are also reduced in cross section. In this way, variable damping characteristics for pressure damping over the entire speed range are achieved. The highest pressure damping is achieved when the axial slide 34 has closed the bypass radial bores 15 .

Since, in particular, the pressure damping has a crucial importance for driving comfort, a very large range for the adjustment possibility is achieved in the case of the pressure damping assigned, the above-described, spring-loaded bypass damping valve. The bypass damper valve, which consists of either a bypass valve body 20 or a valve plate 37 , can be largely varied in the damping force by replacing the bypass valve spring 19 or its bias change, while the piston associated pressure-acting damping valve 18 or 27 gives the maximum identifier of the pressure damping force. The slider 16 or the axial slide 34 enables a continuous cross-sectional change of the bypass cross-section, so that not only variable damping characteristics can be achieved over the entire speed range, but also a large range of adjustment possibilities and the created adjustment device itself are very simple in construction and assembly is.

Claims (7)

1. Vibration damper with adjustable damping force for vehicles, wherein in a cylinder a piston equipped with damping valves and connected to a piston rod connects the cylinder interior filled with damping fluid into two working spaces, while for adjusting the damping force the damping valves a variable depending on a control variable, in the pulling and pushing direction of the piston rod acting bypass is assigned, which has arranged in the piston rod and can be changed by means of a slide cross-section channels, characterized in that the pressure damping associated with spring-loaded bypass damping valve (bypass valve spring 19 ; bypass valve body 20 , valve plate 37 ) parallel to the pressure direction associated Dämpfven valve ( 18 , 27 ) arranged and upstream in the flow direction effective as after throttle, cross-sectional changeable channel (Radialboh tion 15 ). 2. Vibration damper according to claim 1, characterized in that the bypass damping valve (bypass valve spring 19 , bypass valve body by 20 , valve plate 37 ) in an axial bore ( 17 ) of the piston ( 7 , 25 ) receiving the piston rod pin ( 23 ) is angeord net. 3. Vibration damper according to claims 1 and 2, characterized in that the bypass valve body ( 20 ) is cup-shaped and the cup edge forms the contact surface for the bypass valve spring ( 19 ). 4. Vibration damper according to claims 1 to 3, characterized in that the pressure damping associated bypass damping valve (bypass valve spring 19 ; bypass valve body 20 , Ventilplat te 37 ) is combined with a damping force acting in the damping position. 5. Vibration damper according to claims 1 to 4, characterized in that the bias of the Bypaßventilfeder (19) is variable from one axial slide (34) and this thrust is slide (34) arranged to change in cross section of the Bypaßkanales (radial bores 15). 6. Vibration damper according to claims 1 to 5, characterized in that the bypass valve body ( 20 ) has a pre-opening cross section ( 32 ) acting in the pulling and pushing directions. 7. Vibration damper according to claims 1 to 6, characterized in that each radial bore ( 15 ) of the bypass channel is assigned a radial channel ( 33 ) assigned in the piston ( 7 ).