DE10135261C1 - Gas spring/damper unit, for a vehicle shock absorber system, has sprung disks acting on the sealing disks at the overflow throttles, to give a progressive opening action over an opening path of less than 1 mm - Google Patents

Abstract

The invention relates to a gas spring damper unit comprising overflow throttles (23, 24) which are closed in one direction, generally by means of an elastic sealing disk (21,22). Said sealing disks (21,22) have a linear opening characteristic element which, for example, weighs on the driving safety and the driving comfort of a motor vehicle. For this reason, a novel overflow throttle (23,24) is provided, which comprises a progressive opening course over a required opening path of less than 1 mm. To this end, the elastic sealing disks (21,22) of the overflow throttles (23,24) are respectively mounted by at least one elastic element. The spring characteristic element of the elastic sealing disks (21,22) respectively determines the opening characteristic element in a harder damping phase, and the spring characteristic element of each of the elastic elements determines the opening characteristic element in a softer damping phase. Preferably, the elastic element is an elastic ring disk (27).

Description

The invention relates to a gas spring damper unit according to the preamble of claim 1.

Gas spring damper units of this type are predominantly used in the chassis vehicles used.

In the chassis of motor vehicles, the gas spring damper units basically have the task of making the wheels and the vehicle body elastic on the one hand, i.e. resilient connect and on the other hand the excitation vibrations emanating from the wheels compared to the vehicle body to a tolerable and comfortable size fen.

For this purpose, such a gas spring damper unit consists of a cylindrical housing with a cover and a double-acting piston fitted in the housing a one-sided piston rod penetrating the cover. The housing on the one hand and the piston rod on the other hand are fixed to a body part or to the wheel suspension connected, the exposed part of the piston rod by a bellows is covered. This bellows is on the one hand on the cover of the housing and on the other Head of the piston rod attached.

The piston divides the cylinder chamber of the housing into one that compresses when compressed nerner and an enlarging pressure space, both of them on the outside Housing connection with a pressure corresponding to the pressure in the pressure chambers of the load  constant compressed air source and with each other by one or more, in the col ben arranged overflow restrictors are connected.

From DE 84 13 300 U1 an overflow throttle is now known, in which a central one Throttle channel in the piston is covered by a flexible washer. This ring disc has on the one hand an outer sealing surface and on the other hand an inner sealing surface, so that the washer is in a flow direction on the outer edge and in the different flow direction on the inner edge of the respective contact surface. Due to the different distance between the two sealing surfaces compared to the center of the Ring disc results in different lever arms that work for both flow directions cause different opening characteristics for the washer. With this common type of overflow throttle, it is disadvantageous that the ratio of the two opening characteristics with a once selected construction set size is and therefore no longer changeable and in different applications is customizable. In addition, this construction is complex and expensive.

A further overflow throttle is described in DE 199 32 717 A1 by the applicant ben, which is formed from a plurality of individual overflow restrictors. For this be the piston sits on each pressure side of an annular channel, each lying on the inside the piston side is sealed with a resilient sealing washer and each over Through holes evenly arranged on a pitch circle with the opposite lying pressure cables of the piston are connected. So that is every flow direction assigned an overflow throttle with several through holes. Everybody is there of the two sealing washers axially fixed in its inner diameter range tensioned so that the sealing washer is in contact with a corresponding pressure load the outer diameter area from its sealing abutment surface. In addition, the two oppositely acting sealing washers are springy characteristics determining differently, so that in both Set different opening pressures in the flow directions.  

Overflow restrictors of this type have the disadvantage that the resilient sealing washer ben have a linear or a quasi-linear opening characteristic. That leads there to ensure that the resilient sealing washer over the entire pressure, depending on its design difference range reacts equally softly or equally hard. There is too soft a seal in the lower pressure differential range is just as harmful as a seal that is too hard disc in the upper pressure differential range, since the overflow throttle is either at low against excitation frequencies and thus the vehicle at low pressure differences not adequately dampen construction or at high excitation frequencies and thus ho hen pressure differences produce too high spring forces and thus high natural axis frequencies These circumstances affect both driving safety and driving comfort continued.

A telescopic vibration damper is now described in DE 44 45 926 C1 a first annular space covered with a plate washer and a further ring space that is covered by another plate. Both ring spaces are connected to each other via a channel, so that the two plate washers in their opening characteristic are rectified. This doubles the pressure effective Surface so that spring washers with a large bending length can be used NEN. The disadvantage is that two throttle plate valves are required for one throttle direction Lich, which make the effort complicated and expensive. In functional terms disadvantageous that the channel connecting the two annular spaces exerts a throttling effect and thus both throttle plate valves open at different times and different opening have pathways.

Another damping valve was known from DE 40 25 115 A1. Be here the flow bores of the piston with a prestressed spring washer gerer stiffness covered, which is exposed via an annular body Support the scope of a downstream spring washer package with higher spring stiffness. With a low flow rate, only the spring washer opens and gives one  inner passage free and with a larger flow rate the spring washers open be and the spring washer pack, the spring washer pack having an outer stream path opens.

The disadvantage here is that the production is relatively complex and in the first Opening stage the inner flow path is very pressure lossy and in the second Opening stage of the flow stream is divided. This also increases the flow losses.

A similar vibration damper is described in DE 197 55 994 A1 also a covering spring washer for a first opening step and additional Fe the disc package, which, in conjunction with the spring washer, opens a second time level enables. The spring washer and the spring washer pack are by one spaced from each other on the outer diameter ring. This ring is relative large-scale and secured radially by a diameter shoulder. That complicated and makes the vibration damper more expensive. In addition, the ring lies in the flow area and hampers the flow.

The invention is therefore based on the object of a gas spring damper unit to further develop the existing type in such a way that the overflow throttles are opening path of less than 1 mm on a progressive opening course point.

This object is achieved by the characterizing features of claim 1. Appropriate design options result from subclaims 2 until 5.

The new gas spring damper unit eliminates the disadvantages of the prior art Technology. It contributes in particular to improving driving safety and driving comfort continues, in which a constantly adjusted damping over the entire load range  is made possible. In addition, the gas spring damper unit is simple in construction and therefore inexpensive to manufacture.

This is made possible by the corresponding sealing washer of the overcurrent throttles sel not fixed, but only by a spring force for a predetermined pressure difference remains clamped and then also lifts off in the clamping area. It is it particularly expedient through this resilient force to load the sealing washer  to apply a likewise resilient washer. But it is also possible for this to use any other kind of spring.

It is also conceivable to develop a characteristic curve from more than two linear sub-areas to achieve in which the spring force acting on the sealing washer by two and more spring elements connected in series is generated.

The invention will be explained in more detail using an exemplary embodiment.

To show:

Fig. 1 shows a pneumatic spring damper unit according to the prior art, in section,

Fig. 2: the piston of the gas spring damper unit in partial section and

Fig. 3: the overflow throttle in an enlarged partial section.

According to FIG. 1, the pneumatic spring damper unit of a cylindrical housing 1 having a housing wall 2, a housing base 3 for mounting with a Radaufhän supply of a motor vehicle and the housing base 3 opposite Gehäu's lid. 4 In a conventional manner, a piston 5 is fitted in the housing 1 , which has a piston rod 6 on the one hand. This piston rod 6 penetrates the housing cover 4 and is equipped at its free end with a piston rod head 7 which is provided for abutment against the body of the motor vehicle. The part of the piston rod 6 protruding from the housing 1 penetrates a pressure chamber which is enclosed by a bellows 8 in such a way that the bellows 8 is fastened on the one hand to the housing cover 4 and on the other hand to the piston rod head 7 . The piston 5 is sealed against the cylinder wall 2 with a piston ring 9 and thus divides the existing inner space of the housing 1 into a first pressure chamber 10 and a second pressure chamber 11 . The second pressure chamber 11 is functionally connected to the pressure chamber surrounded by the bellows 8 via a connecting channel 12 located in the piston rod 6 . Via a compressed air connection 13 , one of the two pressure spaces 10 , 11 is connected to a compressed air source, which generates a desired pressure in both pressure spaces 10 , 11 and keeps it constant. In the piston 5 there is an overflow throttle 14 , which connects the two pressure chambers 10 , 11 in both directions and via which, with a corresponding movement of the piston 5, a volume equalization of the compressed air is carried out.

According to FIGS. 2 and 3, the piston 5 and piston rod 6 are to split in two from out and connected in the manner to each other that the piston 5 is pushed and the piston rod 6 to a stop by an inner Kolbeneinspannring 15 and an outer Kolbeneinspannring 16 is braced against the piston rod 6 .

To form the overflow throttle 14 , the piston 5 has on the one hand a first annular groove 17 and on the other hand a second annular groove 18 , both of which are each formed as a compressed air collecting space. The first annular groove 17 is connected via a plurality of first through holes 19 to the opposite first pressure chamber 10 and the second annular chamber 18 via a plurality of second through holes 20 with the opposite second pressure chamber 11 . The through holes 19 , 20 are preferably arranged uniformly on a common pitch circle and aligned so that the first through holes 19 bypass the second ring channel 18 and the second through holes 20 the first ring channel 17 .

The first ring channel 17 is covered by a first resilient sealing washer 21 and the second ring channel 18 is covered by a second resilient sealing washer 22 . Thus, the first resilient sealing washer 21 , the first annular groove 17 and the first through holes 19 form a first overflow throttle 23 opening in the direction from the first pressure chamber 10 to the second pressure chamber 11 and the second resilient sealing washer 22 , the second annular groove 18 and the second through holes 20 a second overflow throttle 24 opening in the direction from the second pressure chamber 11 to the first pressure chamber 10 . In the cover of the annular grooves 17, 18 by the two resilient seals 21, 22, the two sealing disks 21, 22 the use case to be biased accordingly by a Versalz in the height of the piston 5, or even out of the gap to the piston 5 oriented.

The first overflow throttle 23 and the second overflow throttle 24 thus act like check valves in opposite directions. To realize different opening pressures, the first overflow throttle 23 has two first resilient sealing disks 21 and the second overflow throttle 24 has only one resilient sealing washer 22 .

As FIG. 3 also shows the first overflow throttle 23 and the second via are formed strömdrossel 24 in a special way. This special design is explained below using the first overflow throttle 23 .

Thus, the outer piston clamping ring 16 has on its side facing the first overflow throttle 23 an annular spring chamber 25 , which is limited in its large diameter range by a collar 26 . This collar 26 is designed as an abutment for a resilient washer 27 and has a corresponding support surface on which the resilient washer 27 lies on its large diameter range. Between the resilient washer 27 and the first resilient sealing washer 21 there is a spacer ring 28 which is arranged in the smaller diameter range of the first fe-resilient sealing washer 21 and the resilient washer 27 . The spacer ring 28 clamps the first resilient sealing washer 21 in its inner diameter range with respect to the piston 5 and is supported against the exposed inner diameter range of the resilient annular washer 27 . This acting on the spacer ring 28 support force is formed by the internal clamping force of the resilient washer 27 and by the resulting from the installation conditions of the resilient ring disc 27 biasing force.

Among these, the biasing force affecting the installation conditions of the resilient washer 27 includes an axial adjustment of the outer Kolbeneinspannringes 16, the bearing surface of the collar 26 in the move relative to the support surface on the spacer ring 28th

To the biasing force influencing installation conditions also includes the ra diale distance of the collar 26 , which determines the length of the lever arm for the resilient ring disc 27 .

The distance obtained by the distance ring 28 between the first resilient sealing washer 21 and the resilient washer 27 is dimensioned such that the first resilient sealing disc 21 is in its mm wide range of diameters sufficient spring path of at least 0.2.

The travel required for the freedom of movement of the inner diameter range of the resilient ring disc 27 is realized by a corresponding depth of the ring-shaped spring chamber 25 .

To achieve a progressive opening course of the two overflow restrictors 23 , 24 , the corresponding resilient washers 27 and the associated springs, the sealing washers 21 , 22 are matched in their spring stiffness so that the resilient ring washer 27 is designed to be weaker than the resilient sealing washer 21 .

The piston 5 also has a bypass throttle 29 which acts in both directions and which ensures low damping forces with very slow excitations.

The mode of operation of a gas spring / damper unit is generally known, so that only the mode of operation of the novel overflow throttle 14 , specifically using the example of the first overflow throttle 23 , needs to be discussed at this point. In the pressure-balanced initial position, the first resilient sealing washer 21 is pressed onto the piston 5 by the force of the design-related preload, and the first ring channel 17 is thus sealed. So that the direction of flow of the compressed gas from the second pressure chamber 11 to the first pressure chamber 10 is blocked. Because of the pressure equalization, no compressed air flows through the bypass throttle 29 .

At a pressure difference from the second pressure chamber 11 to the first pressure chamber 10 , the overflow throttle 23 is sealed, so that compressed air can only compensate for itself in a soft damping phase via the bypass throttle 29 . The course of the flow characteristic of this soft damping phase is non-linear and hardens with increasing pressure difference.

At a pressure difference from the first pressure chamber 10 to the second pressure chamber 11 , the bypass throttle 29 acts again in a softer damping phase before, with a correspondingly larger pressure difference, the first resilient sealing washer 21 lifts off with its outer diameter range from the contact surface of the piston 5 in a harder damping phase and one Flow gap releases so that the compressed air can flow in the same way from the first pressure chamber 10 to the second pressure chamber 11 . The first resilient sealing washer 21 remains clamped with its inner diameter range by the force of the prestressed resilient washer 27 . In this harder damping phase, which extends to compensate for the opening force acting on the first resilient sealing washer 21 with the biasing force of the resilient ring washer 27 , there is a linear opening characteristic, the increase of which is determined solely by the spring characteristic of the first resilient sealing washer 21 .

At a pressure difference between the first pressure chamber 10 and the second pressure chamber 11 that exceeds the preload force of the resilient ring disk 27 , the inner diameter area of the first resilient sealing disk 21 also lifts off its contact surface on the piston 5 in a softer damping phase, the first resilient sealing disk 21 in their previous oblique and tense position remains. This increases with the lifting of the resilient sealing washer 21 in the inner diameter water area and the throttle gap located in the outer diameter area. For this softer damping phase there is again a linear opening characteristic, the increase of which, however, is now determined by the resultant of the spring forces of the first resilient sealing washer 21 and the resilient annular washer 27 . Due to the series circuit of the resilient sealing washer 21 and the resilient ring washer 27 , the increase in the opening characteristic in the softer damping phase is steeper and therefore softer.

Both linear opening characteristics, taken together, result in an approximately progressive course over the total opening path of the resilient sealing disks 21 , 22 .

List of reference numbers

1

casing

2

housing wall

3

Case foot

4

housing cover

5

piston

6

piston rod

7

Piston rod head

8th

bellows

9

piston ring

10

First pressure room

11

Second pressure room

12

connecting channel

13

Compressed air connection

14

Overflow restrictor

15

Inner piston clamping ring

16

Outer piston clamping ring

17

First ring groove

18

Second ring groove

19

First through hole

20

Second through hole

21

First resilient sealing washer

22

Second resilient sealing washer

23

First overflow throttle

24

Second overflow throttle

25

spring chamber

26

Federation

27

Spring washer

28

spacer ring

29

bypass throttle

Claims (5)

1. Gas spring damper unit, consisting of a cylindrical, filled with compressed gas housing ( 1 ) and a double-acting piston ( 5 ) with a piston rod ( 6 ), the housing ( 1 ) and the piston rod ( 6 ) between two relative to each other movable components are clamped and the piston ( 5 ) separates the cylinder chamber of the housing ( 1 ) into a first pressure chamber ( 10 ) and a second pressure chamber ( 11 ) and both pressure chambers ( 10 , 11 ) for the purpose of volume compensation by an overflow throttle ( 14 ) are connected to each other in the piston ( 5 ), the overflow throttle ( 14 ) consisting of a first overflow throttle ( 23 ), a second overflow throttle ( 24 ) and the two overflow throttles ( 23 , 24 ) arranged spatially separated from one another, in opposite directions aligned and equipped with one or more cantilevered and resilient sealing washers ( 21 , 22 ), characterized in that the resilient sealing discs ( 21 ) of the first overflow throttle ( 23 ) and the resilient sealing washers ( 22 ) of the second overflow throttle ( 24 ) are each clamped by at least one resilient element, the spring characteristic of the resilient sealing washers ( 21 , 22 ) of both overflow throttles ( 23 , 24 ) each the opening characteristic in a harder damping phase and the spring characteristic of each of the resilient elements of both overflow restrictors ( 23 , 24 ) determines the opening characteristic in a softer damping phase, the spring-loaded sealing washers ( 21 , 22 ) being clamped in their inner diameter range and that Resilient element is a resilient washer ( 27 ), which is arranged at an axial distance from the respective resilient sealing washers ( 21 , 22 ), which is supported at a radial distance from the clamped diameter range of the resilient sealing washers ( 21 , 22 ) on an abutment and which with its resilient diameter range the in neren diameter range of the resilient sealing washers ( 21 , 22 ) loaded. 2. Gas spring damper unit according to claim 1, characterized in that the resilient ring washers ( 27 ) are planar and that for spacing and for transmitting the force of the resilient ring washer ( 27 ) to the resilient sealing washers ( 21 , 22 ) between the resilient ring washers ( 27 ) and the resilient sealing washers ( 21 , 22 ) a spacer ring ( 28 ) is arranged. 3. Gas spring damper unit according to claim 2, characterized in that the abutment for supporting the resilient ring washers ( 27 ) is designed as a stop for the maximum travel limitation of the resilient sealing washers ( 21 , 22 ). 4. Gas spring damper unit according to claim 3, characterized in that the abutment for supporting the resilient ring discs ( 27 ) by a, a spring chamber ( 25 ) radially delimiting collar ( 26 ) on the inner piston clamping ring ( 15 ) and on the outer Piston clamping ring ( 16 ) is formed. 5. Gas spring damper unit according to claim 1, characterized in that the piston ( 5 ) has a parallel to the first Überströmdros sel ( 23 ) and the second overflow throttle ( 24 ) arranged and acting in both directions bypass throttle ( 29 ).