GB1569157A

GB1569157A - Vibration damper

Info

Publication number: GB1569157A
Application number: GB49744/76A
Authority: GB
Original assignee: Weser AG
Current assignee: Weser AG
Priority date: 1975-11-28
Filing date: 1976-11-29
Publication date: 1980-06-11
Also published as: DK414276A; FR2333168A1; BE847181A; NL7609705A; SE7610979L; DE2553504A1; NO764038L; IT1076490B

Description

(54) VIBRATION DAMPER (71) We, AKTIENGEsELLscHAFT "WESER", a joint stock company organised under the laws of Germany, of 28 Bremen 21, Werfstrasse 160, GERMANY, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : -- The invention concerns a vibration damper, and particularly but not exclusively, a vibration damper for large masses, in which working spaces filled with liquid are connected together by a constriction, and the volume of at least one working space is variable by the movement of a piston connected to the mass.

Vibration dampers, in which a piston operates in a cylinder filled with liquid andfor gas, and is guided on one side by its piston rod in the cylinder cover or in the cylinder bottom are known in various constructions, in particular as shock absorbers for motor vehicles. The connection of the two working spaces in the cylinder consists of holes drilled in the piston or in the piston rod, or of a bypass conduit with a constriction, which in some cases is adjustable.

For sealing the piston against the cylinder wall and for sealing the passage of the piston rod through the cylinder cover or cylinder bottom, sliding seals have hitherto been used which, for reasons of their constructional principle, are suitable for large vibration amplitudes and low frequencies, if certain precautions are taken. Sliding seals are subject to wear. Leakage losses are to be expected, at least under high loads. As damping means for vibratable systems and/ or high vibration frequencies, the known vibration dampers cannot be used.

In addition, sleeves made of resilient material for protective envelopment of moving components, in particular sleeves of pleated bellows construction, are also known. It is also known to replace sliding seals with bellows in the hydraulic damper art.

According to the present invention there is provided a vibration damper comprising a housing enclosing a first working space which communicates with a second working space through a constriction, the working spaces being filled with liquid and the volume of one of the spaces being variable by the movement of a piston, the piston being secured to a piston rod which extends through a passage through the wall of the housing, the housing and the piston rod being connectable between the parts, the relative movement of which is to be damped, the periphery of the piston being spaced from the wall of the housing and the damper including one or more tubular members for sealing between the piston and housing, the member or members being variable in length in the direction of movement of the piston in the working space and being fixed at one end to the piston and at the other end to the housing the arrangement being such that the liquid displaced on movement of the piston is forced without loss through the constriction and the size of the constriction being such as to produce a pressure build-up which acts as the damping force on a vibration.

The tubular member avoid sliding seals and ensure an absolute leak-proof and wearfree sealing of the piston with respect to the housing. The same or another tubular member may be used for sealing the pistonrod passages through the housing cover or housing bottom, so that the volume of the working spaces is fixed exactly, and is variable solely by the piston movement.

The liquid (hydraulic oil) displaced on the slightest piston movement in the working space is forced without loss into another space, a constriction producing a pressure build-up, which acts as damping force on a vibration. The piston can be moved only to the extent that a liquid exchange across the narrow constriction between the working spaces is possible. The cross-section of the constriction may at the same time be reduced to provide a vibration damper which reacts to vibrations of extremely small amplitude and to vibrations having a higher frequency than, for example, occurs in shock absorption in the case of motor vehicles. It is in particular suitable for damping high frequency vibrations. Fitting is carried out in the usual manner in that the housing and the outwardly led end of the piston rod, which according to a further particular embodiment of the invention may be guided both in the cylinder cover and in the cylinder bottom and hence two-fold, are fixed to different parts, on the one hand to the vibratable system, whose vibrations are to be damped by the vibration damper and as far as possible eradicated, and on the other hand to as large a mass as possible, for example a foundation or the like.

A preferred field of application of vibration dampers according to the invention is afforded by relatively large apparatus, for example condensers, especially when provided on ships.

To form the tubular member to suit the high pressures in the working spaces, pleated metal bellows pipes having high elasticity in the longitudinal direction of the pleated bellow may be provided.

To facilitate assembly and constructive embodiment of the idea of the invention, the housing of the vibration damper, in one advantageous embodiment, is subdivided into two working spaces of equal size by a flange projecting from the inner surface of the advantageously cylindrical housing, one end of each of two tubular members surrounding the piston being fixed to the said flange and the other end being connected in a leak-proof manner to the piston.

For the same reason, respective tubular members surround the piston rod one on either side of the piston and are connected by one end of the inner side of the housing cover or housing bottom and by the other end to the piston face turned towards the housing cover or towards the housing bottom. In all cases, the tubular members avoid seals between parts which slide over one another.

Two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: - Figure 1 shows a diagrammatic vertical central section of a first vibration damper; and Figure 2 shows a similar view of a second vibrator damper.

The vibration damper of the embodiment of Figure 1 has an inner piston 1, arranged in a housing 2 which has working spaces A and B. The piston 1 is guided on both sides by piston rods 3 which pass through the cover and bottom of the housing. An inner flange 4 divides the two working spaces A and B from each other. Secured to the said flange 4 is one end of each of two sets of bellows 5 and 6, whose other end is connected in a leak-proof manner to the piston 1 approximately in the vicinity of the piston faces. In the embodiment shown, the piston 1 passes through the central aperture of the flange with a certain clearance, so that guiding of the piston directly on the cylinder does not take place. On either side of the piston a respective set of bellows 7, 8 is provided, surrounding the piston 3, one end of the said sets of bellows being fixed in a leak-proof manner to the cover part, or to the bottom part of the housing 2, their other ends being fixed in a leak-proof manner to the piston faces turned towards the cover part or bottom part respectively.

The embodiment example of Figure 1 shows a housing 2 having two equally large working spaces A and B, connected together by means of a connecting conduit 9, in which a constriction 10 has been inserted. This constriction 10 may be in the form of a variable or invariable constriction. Screw plugs, not shown in the drawing, are provided for filling and emptying the two working spaces A and B.

The embodiment example of Figure 2 shows a vibration damper, in which the piston 1 is arranged in the working space A of a housing 2 filled with liquid and this housing 2 is connected to a second housing 11, whose inner space represents the second working space and is also filled with liquid.

The two working spaces A and B are connected together hydraulically via the constriction 10. The bellow 7 in the embodiment of Figure 2 seals the piston rod 3 and the piston 1 to the housing 2 respectively.

In the working space B of housing 11, there is provided a piston-like buffer 12, which is supported against a resilient abutment, a spring 13 or the like, so that the volume of this working space B is variable by the movement of the buffer 12, if by the movement of the piston 1 in the working space A liquid is forced through the construction 10 into the working space B. The resilience or springing of the buffer 12 forces the liquid back into the working space A. The buffer 12 can be adjusted from the outside by means of an adjusting screw 14.

WHAT WE CLAIM IS : - 1. A vibration damper comprising a housing enclosing a first working space which communicates with a second working space through a constriction, the working spaces being filled with liquid and the volume of one of the spaces being variable by the movement of a piston, the piston being secured to a piston rod which extends through a passage through the wall of the housing, the housing and the piston rod being connectable between the parts, the relative movement of which is to be damped, the periphery of the piston being spaced from the wall of the housing and the damper including one or more tubular

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. damping high frequency vibrations. Fitting is carried out in the usual manner in that the housing and the outwardly led end of the piston rod, which according to a further particular embodiment of the invention may be guided both in the cylinder cover and in the cylinder bottom and hence two-fold, are fixed to different parts, on the one hand to the vibratable system, whose vibrations are to be damped by the vibration damper and as far as possible eradicated, and on the other hand to as large a mass as possible, for example a foundation or the like. A preferred field of application of vibration dampers according to the invention is afforded by relatively large apparatus, for example condensers, especially when provided on ships. To form the tubular member to suit the high pressures in the working spaces, pleated metal bellows pipes having high elasticity in the longitudinal direction of the pleated bellow may be provided. To facilitate assembly and constructive embodiment of the idea of the invention, the housing of the vibration damper, in one advantageous embodiment, is subdivided into two working spaces of equal size by a flange projecting from the inner surface of the advantageously cylindrical housing, one end of each of two tubular members surrounding the piston being fixed to the said flange and the other end being connected in a leak-proof manner to the piston. For the same reason, respective tubular members surround the piston rod one on either side of the piston and are connected by one end of the inner side of the housing cover or housing bottom and by the other end to the piston face turned towards the housing cover or towards the housing bottom. In all cases, the tubular members avoid seals between parts which slide over one another. Two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: - Figure 1 shows a diagrammatic vertical central section of a first vibration damper; and Figure 2 shows a similar view of a second vibrator damper. The vibration damper of the embodiment of Figure 1 has an inner piston 1, arranged in a housing 2 which has working spaces A and B. The piston 1 is guided on both sides by piston rods 3 which pass through the cover and bottom of the housing. An inner flange 4 divides the two working spaces A and B from each other. Secured to the said flange 4 is one end of each of two sets of bellows 5 and 6, whose other end is connected in a leak-proof manner to the piston

1 approximately in the vicinity of the piston faces. In the embodiment shown, the piston 1 passes through the central aperture of the flange with a certain clearance, so that guiding of the piston directly on the cylinder does not take place. On either side of the piston a respective set of bellows 7, 8 is provided, surrounding the piston 3, one end of the said sets of bellows being fixed in a leak-proof manner to the cover part, or to the bottom part of the housing 2, their other ends being fixed in a leak-proof manner to the piston faces turned towards the cover part or bottom part respectively.

members for sealing between the piston and housing, the member or members being variable in length in the direction of movement of the piston in the working space and being fixed at one end to the piston and at the other end to the housing, the arrangement being such that the liquid displaced on movement of the piston is forced without loss through the constriction and the size of the constriction being such as to produce a pressure build-up which acts as the damping force on a vibration.

2. A vibration damper according to claim 1, in which the tubular member or members are pleated metal bellows which are resilient in the longitudinal direction.

3. A vibration damper according to claim 1 or 2 in which the housing encloses the first and the second working spaces and has a flange which projects from its inner surface and divides the interior of the housing into the two working spaces, the piston extending through the flange, two tubular members surrounding the piston on opposite sides of the flange and being connected in leak-proof manner at one end to the flange and at the other end to the piston.

4. A vibration damper according to claim 3 in which the two working spaces are of equal size.

5. A vibration damper according to claims 1 to 4 in which a tubular member surrounds the piston rod, one end of the tubular member being secured in leak-proof manner to the inner side of the housing cover or the housing bottom and the other end being secured to the face of the piston that is turned toward the said inner side.

6. A vibration damper according to claim 5 in which the piston rod which extends from both faces of the piston, the two ends of the piston rod being guided in the housing cover and the housing bottom, there being a tubular member as set out in claim 6 surrounding the piston rod on each side of the piston.

7. A vibration damper according to claim 1 in which the second working space is equipped with a resilient buffer, whose movement produces a variation in volume of the said second working space.

8. A vibration damper according to claim 8 in which the resilient buffer is adjustable.

9. A vibration damper substantially as hereinbefore described with reference to the accompanying drawings.