DE102020110325A1 - Vibration damper - Google Patents

Abstract

The invention relates to a particularly hydraulic vibration damper with a cylinder which has a fluid chamber in the interior which is axially delimited by two cylinder covers and is filled with a fluid, a piston which is mounted displaceably within the fluid chamber of the cylinder and which separates the fluid chamber into a first and a second chamber, and one or two piston rods connected to the piston, which extend through at least one of the cylinder covers and are slidably mounted in the latter. The at least one cylinder cover in which the piston rod is mounted has at least one seal which seals the fluid chamber from the outside in a liquid-tight and / or gas-tight manner. According to the invention, a contactless seal is additionally arranged between the fluid chamber and the seal.

Description

The present invention relates to a, in particular hydraulic, vibration damper according to the preamble of claim 1.

Vibration dampers, especially hydraulic vibration dampers that are filled with an oil, are used in a variety of applications to dampen mechanical vibrations by converting the vibration energy into heat. Vibration dampers of this type are used, for example, as shock absorbers on vehicles or to protect structures from damaging vibrations such as those caused by people, machines, wind or earthquakes.

Typical vibration dampers known from the prior art are based on a cylinder which has a fluid chamber filled with fluid in which a piston is displaceably mounted. In the event of an external force acting on the piston, the fluid in the cylinder is displaced by one or more damping elements which oppose the displaced fluid with a resistance. This creates a pressure difference that opposes the piston moving relative to the cylinder with a damping force.

The damping elements, for example in the form of damping valves, are usually arranged in the piston, so that the displaced fluid is forced from the pressure side through the piston to the low-pressure side. Alternatively, a fluid channel can be provided in which one or more damping elements are arranged, which connects the fluid chamber to one another on both sides of the piston.

Seals are used to seal off the fluid chamber of the cylinder from the environment. In known hydraulic vibration dampers, elastomer seals are often used here, which are designed as a liquid-tight shaft seal and are arranged on the guide of the piston rod in or on the cylinder housing.

When the vibration damper is stressed by the pressures that occur, these elastomer seals are exposed to high loads and therefore increased wear and tear, and due to the increased coefficients of friction, they lead to short downtimes and maintenance intervals. As part of maintenance measures, it is sometimes very costly and time-consuming to replace worn elastomer seals.

Against this background, the object of the present invention is to provide a vibration damper which, compared to known devices, requires less maintenance.

According to the invention, this object is achieved by a vibration damper, in particular a hydraulic vibration damper, with the features of claim 1. Accordingly, the vibration damper according to the invention comprises a cylinder, which in the interior has a fluid chamber which is axially delimited by two cylinder covers and filled with a fluid, a piston which is mounted displaceably within the fluid chamber of the cylinder and which separates the fluid chamber into a first and a second chamber, and one with the piston rod connected to the piston, which extends through at least one of the cylinder covers and is slidably mounted therein. The at least one cylinder cover in which the piston rod is mounted has a seal that seals the fluid chamber from the outside, i.e. from the environment, in a liquid-tight and / or gas-tight manner. If the fluid is a liquid, e.g. oil, the seal is liquid-tight. If the fluid is a gas, it is gas-tight.

According to the invention, a contactless seal is additionally arranged between the fluid chamber and the seal. The term "contactless seal" is to be interpreted broadly and is to be regarded as a means (pressure reducing means or damping element) which is designed to generate a pressure difference between the fluid chamber and the side facing the seal, i.e. to reduce the pressure. In principle, for example, a pressure reducing valve can therefore also be viewed as a contactless seal in this sense.

The additional integrated non-contact seal reduces the pressure applied to the (outer) seal, which leads to less friction and thus a longer service life of the seal. Due to the reduced wear of the seal, it has to be replaced less frequently, which considerably reduces the maintenance effort of the vibration damper according to the invention and extends the maintenance intervals required by changing the seal.

The advantages that result from the provision of an additional contactless or contactless seal exist independently of the size and the intended use of the vibration damper according to the invention. Consequently, the vibration damper according to the invention can be, for example, a shock absorber for a vehicle, for example a car, excavator, mobile crane, etc., or a vibration damper to protect structures from earthquakes, environmental influences or by Vibrations caused by persons or machines.

Advantageous embodiments of the invention emerge from the subclaims and the following description.

In one embodiment, a fluid channel is provided which connects the first and second chambers to one another. This can be, for example, a hose, a channel formed within the cylinder or a combination of such sections. The fluid channel can comprise one or more connections or connecting elements. The fluid channel preferably runs partially outside the cylinder, for example in the form of a hose which is connected to channels formed in the cylinder via connections.

Through the fluid channel, the fluid displaced when the vibration damper is stressed, i.e. when a force is exerted on the piston rod, is transferred from the pressure chamber (i.e. the chamber which lies in front of the piston in the direction of movement of the piston and whose volume is reduced as a result) into the low-pressure chamber (ie the chamber on the other side of the piston, the volume of which increases as a result of the piston movement) is rearranged or initiated.

In a further embodiment it is provided that the fluid channel comprises an inlet channel which is connected to the side facing away from the fluid chamber (ie low pressure side) of the contactless seal and is designed to allow fluid passing through the contactless seal into the chamber on the other side of the piston (Low pressure chamber) to conduct. The inlet channel is preferably formed in the cylinder, in particular within the cylinder cover, and is connected to a part of the fluid channel extending outside the cylinder.

The contactless seal is thus arranged between the fluid chamber and the inlet channel, the inlet channel being arranged between the outer seal and the contactless seal. This arrangement allows the fluid forced from the pressure chamber through the contactless seal to escape via the fluid channel into the low-pressure chamber. The pressure at the outer seal is therefore only lower than that at the pressure chamber.

In a further embodiment it is provided that at least one check valve is provided in the fluid channel, which allows a flow of the fluid from the fluid channel into the fluid chamber, but vice versa blocks it. This ensures that fluid can only escape from the pressure chamber into the low-pressure chamber.

In a further embodiment it is provided that the fluid channel comprises an outlet channel which opens into the fluid chamber and in which the check valve is arranged. In particular, the outlet channel does not end on the low-pressure side of the contactless seal, but directly in the fluid chamber.

In a further embodiment it is provided that the inlet and / or outlet channels are at least partially formed in the cylinder cover. The channels are preferably connected to one another and connected via a connection or a connecting element to a part of the fluid channel extending outside the cylinder. It is also conceivable that some of the channels run within the cylinder jacket or the cylinder casing. The inlet and / or outlet channels are located in particular in the cylinder cover through which the piston rod runs, or in the case of a piston rod running through both cylinder covers in both cylinder covers. In particular, at least one inlet channel is provided for each pair of outer and non-contact seals so that the leakage fluid from each of the non-contact seals can flow off via the fluid channel into the other (low-pressure) chamber.

In a further embodiment it is provided that the piston rod extends on both sides of the piston through both cylinder covers and is mounted displaceably in these. The piston rod advantageously has the same diameter on both sides of the piston. In this embodiment, each cylinder cover has an (outer) seal which seals the fluid chamber from the outside in a liquid-tight and / or gas-tight manner. Accordingly, two contactless seals are provided, one of these contactless seals being arranged between the fluid chamber and one of the (outer) seals.

As a result, the vibration damper according to the invention works in both directions, i.e. each of the chambers separated by the piston can function as a pressure and a low-pressure chamber, depending on the direction of force. A pressure reduced by one of the non-contact seals is applied to each of the seals.

In a further embodiment it is provided that the fluid channel described above comprises an inlet channel and / or an outlet channel with a preferably integrated check valve at each end.

In a further embodiment it is provided that the inlet and / or outlet channels in the cylinder covers and are preferably designed identically. Furthermore, the outer seals, the contactless seals and the inlet and outlet channels together with the check valves are designed to be identical (or mirrored). As a result, the vibration damper according to the invention functions equally in both directions.

In a further embodiment it is provided that the cylinder and piston form a synchronous cylinder, i.e. both piston surfaces are the same size.

In a further embodiment it is provided that the (outer) seal is an elastomer seal and in particular a shaft seal contacting the piston rod.

In a further embodiment, it is provided that the piston separates the first and second chambers from one another in a liquid-tight and / or gas-tight manner (depending on whether the fluid is a liquid or a gas). This means that there are no damping elements such as damping valves in the piston or the piston rod. Instead, the damping effect is achieved by displacing the fluid from the pressure chamber via the contactless seal and finally via the fluid channel into the low-pressure chamber. This enables a simultaneous pressure reduction on the outer seal, which increases its service life.

In a further embodiment it is provided that the contactless seal is a gap seal. Alternatively, another type of non-contact seal such as a labyrinth seal can be used, which also reduces the pressure applied to the outer seal. A valve, e.g. a pressure reducing valve, would also be conceivable here.

In a further embodiment it is provided that at least one of the cylinder covers on the side opposite the fluid chamber borders a further closed fluid chamber which is designed to interact with the piston rod in such a way that the volume of the further fluid chamber varies with the movement of the piston rod. The further fluid chamber is preferably filled with a compressible fluid.

The volume variation of the further fluid chamber as a function of the position of the piston rod can be realized in that the piston rod protrudes through the cylinder cover into the further fluid chamber or by providing a further piston or separating piston at one end of the piston rod, the other side of which is facing away from the fluid chamber Fluid chamber limited.

The further fluid chamber can be filled with a gas and serve as a gas cushion or gas damper for the vibration damper according to the invention. In particular, the vibration damper according to the invention can be a single-tube damper. In this case, the additional fluid chamber or gas chamber filled with gas serves to equalize volume and temperature.

The fluid which is located in the fluid chamber is in particular oil. Alternatively, the fluid can be a gas.

Further features, details and advantages of the invention emerge from the exemplary embodiment explained below with reference to the single figure.

In the (only) 1 is an embodiment of the vibration damper according to the invention 10 in a cross-sectional view along the longitudinal axis of the vibration damper 10 shown. This embodiment is a hydraulic vibration damper 10 .

The hydraulic vibration damper according to the invention 10 includes a cylinder 12th , which has a fluid chamber filled with oil in its interior 18th having at the axial ends of the cylinder 12th of two cylinder covers 14th , 16 and radially from a cylinder shell 13th is limited. In the fluid chamber 18th is a piston 20th slidably mounted of the fluid chamber 18th in two chambers 24 , 26th separates. The piston 20th have a gap seal or one or more elastomer seals.

The piston 20th is with at least one piston rod 22nd connected, extending to both sides of the piston 20th extends, has the same diameter on both sides (synchronous cylinder), extends through each of the two cylinder covers 14th , 16 extends and is slidably mounted therein. The piston rod protrudes on one side 22nd out of the cylinder 12th addition and has a fastening means at the outer end 42 on which the vibration damper 10 can be connected to another component or structure of a vehicle, building or other device. The other end of the piston rod 22nd also protrudes from the corresponding cylinder cover 16 out, but ends in a sticking to the cylinder cover 16 subsequent chamber 40 .

Around the fluid chamber 18th to be sealed liquid-tight against the environment are in every cylinder cover 14th , 16 Elastomer seals 28 arranged, designed as a shaft seal and around the piston rod 22nd are arranged around. Around the load on the vibration damper 10 on the elastomer seals 28 to reduce applied pressure, are adjacent to the fluid chamber 18th , ie between the fluid chamber 18th and the elastomer seals 28 , additional gap seals 30th intended. The gap seals 30th As a non-contact shaft seal, they allow fluid to pass through from the fluid chamber 18th to that of the elastomer seal 28 facing side (low pressure side).

It should be noted at this point that an embodiment is also possible in which the piston rod 22nd only in one of the cylinder covers 14th , 16 is stored and thus only an elastomer seal 28 and a gap seal 30th is provided (differential cylinder).

The vibration damper according to the invention 10 further comprises a fluid channel 32 who put the two through the flask 20th separate chambers 24 , 26th connects with each other. When the vibration damper is stressed 10 becomes a force on the piston rod 22nd exercised so that the piston 20th moved in the direction of the chamber 26. This increases the pressure on the chamber 26th that is between the piston 20th and the further fluid chamber 40 is located. The other chamber points against this 24 lower pressure.

In the following, the term “pressure chamber” is used for that chamber 26th , 24 used in due to the force acting on the piston rod 22nd The pressure is higher than in the other chamber, hereinafter referred to as the “low-pressure chamber” 24 , 26th . Because the vibration damper 10 (essentially) symmetrically constructed and in both directions (with respect to the longitudinal axis of the piston rod 22nd ) works, one or the other chamber can, depending on the direction of the force 24 , 26th represent the "pressure chamber".

The fluid channel 32 includes one outside of the cylinder 12th running part, which in this embodiment is a pipeline 33 is executed and essentially parallel to the piston rod 22nd between the two cylinder covers 14th , 16 runs. In each of the two cylinder covers 14th , 16 is an inlet port 34 formed by the gap between the piston rod 22nd and cylinder cover 14th , 16 or from the low pressure side of each gap seal 30th to a connection means 39 which runs the inlet channels 34 with the pipeline 33 connects. In the present case, it is the connection means 39 Hydraulic connections angled at 90 °. From the inlet ducts 34 runs in each of the cylinder covers 14th , 16 also an outlet channel 36 directly to the fluid chamber 18th . In each of the outlet ducts 36 is a check valve 38 arranged, which allows a flow of fluid from the outlet channel 36 into the fluid chamber 18th allows, but not the other way around. Thus are the inlet ports 34 via the gap seals 30th and the outlet ducts 36 via the check valves 38 with the fluid chamber 18th tied together.

The inlet and outlet channels 34 , 36 as well as the check valves 38 and the connection means 39 are identical and to each other (on one perpendicular to the longitudinal axis of the piston rod 22nd running plane) mirrored. The inlet ducts 34 run vertically and the outlet channels 36 parallel to the piston rod 22nd . Alternatively, it is also conceivable that instead of outside the cylinder 12th running pipeline 33 one in the cylinder shell 13th trained channel is provided. Furthermore, several fluid channels 32 be connected in parallel, possibly each with its own pair of inlet and outlet channels 34 , 36 Etc.

When the vibration damper is stressed 10 , ie when a force acts on the piston rod 22nd , is fluid from the pressure chamber 24 , 26th through the gap seal 30th to the inlet port 34 pushed. This leak fluid can be via the fluid channel 32 into the low pressure chamber 26th , 24 escape via the into the low-pressure chamber 26th , 24 opening outlet channel 36 .

The gap seals 30th thus fulfill a double function. On the one hand, they represent a resistance for the fluid displaced by the action of force and thus ensure the damping effect of the vibration damper according to the invention 10 . On the other hand, they reduce the pressure on the elastomer seal 28 facing side, so that they are less stressed or less friction is generated and they are thus protected. This reduces the wear on the elastomer seals 28 considerably, which increases the service life until the next maintenance interval.

Instead of a hydraulic one, a pneumatic vibration damper could in principle also be used 10 come into use, the fluid chamber 18th is filled with gas instead of fluid and the above-mentioned “liquid-tight” seals are designed to be gas-tight. In this case there is a gap seal 30th used to reduce the gas pressure on the outer seals 28 leads.

The gap seal 30th is only one possible example of a pressure reducing means that is used in the vibration damper according to the invention 10 can be used to fix the elastomer seal 28 reduce applied pressure. Alternatively, a valve could also be provided which fulfills the same function, ie generates a pressure difference and opposes the displaced fluid with a resistance in order to generate a damping effect. The pressure reducing means can thus also be viewed as a damping element.

List of reference symbols

10

Vibration damper

12th

cylinder

13th

Cylinder shell

14th

Cylinder cover

16

Cylinder cover

18th

Fluid chamber

20th

Pistons

22nd

Piston rod

24

First chamber

26th

Second chamber

28

poetry

30th

Contactless seal

32

Fluid channel

33

hose

34

Inlet port

36

Exhaust duct

38

check valve

39

Connection means

40

Another fluid chamber

42

Fasteners

Claims (14)

Vibration damper (10) comprising a cylinder (12) which has on the inside a fluid chamber (18) axially delimited by two cylinder covers (14, 16) and filled with a fluid, a piston (20) mounted displaceably within the fluid chamber of the cylinder (12) ), which separates the fluid chamber (18) into a first and a second chamber (24, 26), and a piston rod (22) connected to the piston, which extends through at least one of the cylinder covers (14, 16) and is displaceable therein is stored, wherein the at least one cylinder cover (14, 16) has at least one seal (28) which seals the fluid chamber (18) liquid- and / or gas-tight to the outside, characterized in that between the fluid chamber (18) and the seal (28) a contactless seal (30) is also arranged. Vibration damper (10) Claim 1 , characterized in that a fluid channel (32) is provided which connects the first and second chambers (24, 26) to one another and preferably runs partially outside the cylinder (12). Vibration damper (10) Claim 2 or 3 , characterized in that the fluid channel (32) comprises an inlet channel (34) which is connected to the side of the contactless seal (30) facing away from the fluid chamber (18) and is designed to allow fluid passing through the contactless seal (30) into the on the other side of the piston (20) lying chamber (24, 26) to guide. Vibration damper (10) Claim 2 or 3 , characterized in that at least one check valve (38) is provided in the fluid channel (32), which allows a one-sided flow of the fluid from the fluid channel (32) into the fluid chamber (18). Vibration damper (10) Claim 4 , characterized in that the fluid channel (32) comprises an outlet channel (36) which opens into the fluid chamber (18) and in which the check valve (38) is arranged. Vibration damper (10) according to one of the Claims 3 until 4th , characterized in that the inlet and / or outlet channels (34, 36) are at least partially formed in the cylinder cover (14, 16). Vibration damper (10) according to one of the preceding claims, characterized in that the piston rod (22) extends at least to one side of the piston (20) through at least one of the two cylinder covers (14, 16) and is slidably mounted in these, each The cylinder cover (14, 16) has at least one seal (28) which seals the fluid chamber (18) from the outside in a liquid- and / or gas-tight manner and with an additional contactless seal (30) between the fluid chamber (18) and the seals (28) ) is arranged. Vibration damper (10) Claim 7 , characterized in that a fluid channel (32) is provided which connects the first and second chambers (24, 26) to one another and preferably partially extends outside the cylinder (12), each end of the fluid channel (32) having an inlet channel (34) after Claim 3 and / or an outlet channel (36) after Claim 5 includes. Vibration damper (10) according to one of the preceding claims, characterized in that the inlet and / or outlet channels (34, 36) in the cylinder covers (14, 16) are preferably identical. Vibration damper (10) according to one of the preceding claims, characterized characterized in that the cylinder (12) and the piston (20) form a synchronous cylinder and / or differential cylinder. Vibration damper (10) according to one of the preceding claims, characterized in that the seal (28) is an elastomer seal. Vibration damper (10) according to one of the preceding claims, characterized in that the piston (20) separates the first and second chambers (24, 26) with a contactless seal and / or with at least one elastomer seal. Vibration damper (10) according to one of the preceding claims, characterized in that the contactless seal (30) is a gap seal. Vibration damper (10) according to one of the preceding claims, characterized in that at least one of the cylinder covers (16) on the side opposite the fluid chamber (18) is adjoined by a chamber (40) which is designed to connect with the piston rod (22) in this way cooperate so that the piston rod (22) cannot strike the fastening element (42).

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