Rail vehicle fluid damper with a monitoring function

Abstract

The invention relates to a rail vehicle fluid damper (1) having a container in which a guide bearing is arranged at the head end and a piston which can be retracted into the container (4) by way of a piston rod (3) so as to pass through the guide bearing with a plate-like head, wherein a statically preloaded fluid medium (7) is located in the container (4), characterized in that a base disc (7) is inserted into a base-side end (6) of the container (4), the base disc (7) being adapted, by way of its outside diameter, to the inside diameter of the sleeve and forming the container base, the base disc (7) being spaced apart from the base-side end (6) of the sleeve by means of a screw-in sleeve (8) and a sensor element (16) being coupled to the base disc (7) on the side remote from the fluid medium (5).

Description

[0001] 26.06.2025 XO / anh

[0002] Our reference number: HYDR019WO

[0003] HYDROSTAT Engineering + Konstruktion GmbH, Lise-Meitner-Str. 4, D-45699 Herten

[0004] Railway vehicle fluid damper with monitoring function

[0005] The present invention relates to a railway vehicle fluid damper according to the features in the preamble of claim 1.

[0006] It is known from the prior art to install dampers at the front or rear of rail vehicles so that, during a coupling process, two rail vehicles, each weighing several tons, can approach each other without damage. These dampers are also called hydrostatic dampers and are known as rail vehicle fluid dampers. The dampers can also be called viscoelastic spring dampers or viscoelastic dampers.

[0007] In the event of a minor collision between two rail vehicles, the resulting forces are absorbed and dampened. These dampers can also be called buffers. Depending on the design of the coupling between the two rail vehicles, another function of such dampers can be to maintain the dynamically changing distance between them during operation. This is particularly relevant when negotiating curves and / or encountering changes in elevation. It is also known that these dampers are preloaded and therefore possess spring-like properties.

[0008] A generic hydrostat is known, for example, from DE 20 2019 102 118 U1.

[0009] Once such a hydrostatic damper is installed, the fluid medium it contains, also referred to as liquid, is under preload. During operation, it is therefore impossible to look inside the damper to draw any conclusions about the fluid, the condition of the seals, or the damper's wear and tear.

[0010] From DE 10 2021 108 106 A1, a system for monitoring a hydrostatic or damper of the type in question is known. In this system, a reference element, in particular in the form of a reference disk, is installed in a hydrostatic damper. The pressure acting on the damper, which changes when the damper is compressed, can be measured by the deformation of the reference disk.

[0011] The object of the present invention is to demonstrate a way of equipping a hydrostatic damper of the type in question with a monitoring function that allows conclusions to be drawn about the wear state or the actual state within the damper with a simple design, but at the same time with an optional permanent evaluation option.

[0012] The aforementioned problem is solved according to the invention with a railway vehicle fluid damper having the features in claim 1.

[0013] Advantageous embodiments of the present invention are the subject of the dependent claims. The present invention relates to a railway vehicle fluid damper. Within the scope of the invention, this railway vehicle fluid damper can also be referred to as a hydrostatic unit, a viscoelastic damper, or a viscoelastic spring. Hereinafter, the railway vehicle fluid damper will also be referred to as a damper. In a purely spring-like operation, the piston retracts into the housing. This retraction movement increases the pressure in the hydrostatic unit, acting here as a hydrostatic or viscoelastic spring. When the retraction force is removed, the increased pressure causes the piston to retract. In the case of a damper, an additional piston is present, which is virtually gap-free or has only a small gap with respect to the inner wall of the housing.When the piston and piston rod are drawn into the housing, not only does the pressure of the medium increase, but friction also arises due to the medium flowing past in the gap, which then produces the damping effect. A throttle bore may also be present in the piston.

[0014] This damper contains a fluid medium, a viscoelastic fluid. This fluid is held in the damper under a preload, preferably greater than 300 bar. The damper includes a reservoir with a guide bearing at its head. A piston, which extends through the guide bearing via a piston rod, has a disc-shaped head and can be retracted into the reservoir.

[0015] The fluid medium inside the container is under static preload. When the disc-shaped head is inserted into the container, the fluid medium is further compressed, thus increasing the pressure. This pressure can rise to approximately 4,000 bar. This high internal pressure leads to a marginal, but measurable, deformation of the container.

[0016] The container wall, and also the container bottom, change their shape due to the high internal pressure. Based on the measured deformation, it is possible to calculate the magnitude of the internal pressure. For this purpose, a bottom disc is inserted at one end of the container. The bottom disc has an outer diameter that is adapted to the inner diameter of the sleeve. Preferably, the outer diameter of the bottom disc corresponds substantially to the inner diameter of the container sleeve, which is sleeve-shaped and hereinafter also referred to as the sleeve or container sleeve. The outer diameter of the bottom disc is designed as a transition fit, preferably a clearance fit, between the outer diameter of the bottom disc and the inner diameter of the container sleeve.

[0017] The bottom disc is inserted into the container from one end near the bottom. A screw-in sleeve is also provided to hold the bottom disc in place. This sleeve has an external thread that screws into an internal thread of the container sleeve. This positions the bottom disc at a distance from the bottom end of the container, offset inwards towards the driver's bearing. The position of the bottom disc can be determined by adjusting the insertion depth of the screw-in sleeve.

[0018] Alternatively or additionally, the static preload pressure in the reservoir can be adjusted via the screw-in depth of the threaded sleeve. Further screwing in of the threaded sleeve increases the compression or pressure on the fluid medium. This represents a further advantage of the invention. Firstly, the pressure can be set. Secondly, the static pressure can be readjusted. For example, after several years of use of the railway vehicle fluid damper, seals and / or the fluid medium may become somewhat depleted. In this case, further screwing in of the threaded sleeve increases the static pressure again. This extends the service life of the railway vehicle fluid damper.The monitoring capability described later does not reduce operational safety, as the pressure in the fluid medium can be measured and monitored both under static preload and when the rail vehicle fluid damper is actuated. Furthermore, a sensor element, specifically a strain gauge, is located on the side of the bottom disc facing away from the fluid medium. When the damper is actuated, the internal pressure increases. Consequently, the bottom disc deforms, allowing for the measurement of the degree of deformation and thus the calculation of the damper's internal pressure.

[0019] Another advantage is that a cavity remains on the side of the screw-in sleeve facing away from the base plate. This cavity can house additional sensors, a transmitter and receiver unit, or other electronic components. Furthermore, the screw-in sleeve can be sealed at its base end with an additional cover. This cover also features a seal. This allows the cavity within the screw-in sleeve to be shielded from the environment, effectively sealing it watertight and / or airtight. The corresponding electronics, specifically the transmitter and receiver unit, are thus reliably installed, yet easily accessible for maintenance by unscrewing the cover of the screw-in sleeve, without having to disassemble the damper itself, which is subjected to a static preload of over 300 bar.

[0020] Furthermore, the housing and the screw-in sleeve are made of metallic material. The cover of the screw-in sleeve can be made of a non-shielding material, such as a plastic or similar, so that data can be transmitted to the environment.

[0021] A further design advantage has surprisingly arisen in that the design with a bottom disc, which has the aforementioned diameter ratio of the bottom disc's outer diameter to the housing's inner diameter, seals the fluid medium inside the damper particularly effectively. For this purpose, the bottom disc has a step or a projecting edge or collar that extends towards the fluid medium. A gap is formed between the inner surface of the housing and the collar. A seal, particularly an annular seal, is inserted into this gap. One end face of the seal thus faces the fluid medium. The pressure exerted by the fluid medium then presses on the end face of the seal, thus pushing the seal towards the bottom disc, and simultaneously also against the inner surface of the housing and the outer surface of the step or collar.The gap in the bottom plate creates a self-sealing effect due to the static preload of the fluid medium. For this purpose, a gasket is used, particularly before filling the damper with the fluid medium or when inserting the bottom plate. This gasket has an interference fit to the inner surface of the housing and to the outer surface of the step. This ensures that no fluid medium can penetrate axially between the gasket and the bottom plate. Furthermore, different bottom plates can be used. For example, the bottom plates can be made of different materials and thus have a corresponding thickness in the axial direction. A bottom plate with recesses can be used, or alternatively, a bottom plate with varying thickness in the axial direction can be used. In particular, the axial thickness increases towards the center of the plate.Therefore, from the outside inwards in the radial direction, the thickness of the bottom disk increases in the axial direction.

[0022] Further advantages, properties, and aspects of the present invention are the subject of the following description. Preferred embodiments are illustrated in the schematic figure. This serves to facilitate understanding of the invention.

[0023] The figure shows a railway vehicle fluid damper in longitudinal view with partial section as well as various types of bottom discs.

[0024] The aforementioned and subsequently described embodiments can be combined individually with one another at will without leaving the scope of the invention.

[0025] The figure shows a longitudinal view of a railway vehicle fluid damper 1 according to the invention. This damper has a piston rod 3 at a head end 2. The piston rod 3 is supported at the head end 2 in a guide bearing (not shown). The piston rod 3 can be moved axially A into the damper 1. A disc-shaped head (also not shown) then compresses the fluid medium 5 located in a reservoir 4 of the damper 1. Initially, the damper 1 is designed under a static preload, preferably more than 300 bar. When the piston rod 3 is moved axially A into the damper 1, this pressure increases, and thus the internal pressure or operating pressure increases to up to 4,000 bar. A relatively thick-walled reservoir wall made of metallic material deforms as a result of the significant pressure increase. A bottom disc 7 is inserted at a bottom end 6.The bottom side 15 is spaced apart from the bottom end 6 of the container 7. A screw-in sleeve 8 is provided to position the bottom disc 7 in the container 4. The screw-in sleeve 8 has an external thread that engages with an internal thread of the sleeve-shaped container. Thus, the position of the bottom disc 7 in the container 4 can be adjusted by varying the screw-in depth in the axial direction A. The bottom disc 7 has a projecting collar 9. This collar 9 creates a stepped shoulder 10 on an outer surface 11 of the bottom disc 7. A seal 12 in the form of a ring seal is inserted into this stepped shoulder 10. The pressure of the fluid medium 5 is applied to an end face 13 of the seal 12. This pressure presses the seal 12 against the stepped shoulder 10 of the bottom disc 7 in the axial direction A. As a result, the seal 12 also expands in the radial direction R.It comes into contact with an inner surface 14 of the container 4 and with an outer surface of the step 10. Thus, the fluid medium 5 is sealed against the bottom disc 7. The outer diameter of the bottom disc 7 corresponds essentially to the inner diameter 14 of the container 4. Any play is sealed by the previously described seal 12. A sensor element 16, for example in the form of a strain gauge, is arranged on the bottom side 15 of the bottom disc 7 opposite the fluid medium. The sensor element 16 measures a deformation of the bottom disc 7 in the axial and / or radial direction R, or stresses occurring in the bottom disc 7. From this, a conclusion can be drawn about the applied pressure of the fluid medium 5. Furthermore, an electronic unit 17, for example as a transmitter and receiver, is connected to the sensor element 16.An interior space 18, formed within the screw-in sleeve 8, is further closed by a cover 19. The cover 19 can additionally be sealed by a further seal 20, so that the interior space 18 is sealed against the environment U. The cover 19 is preferably made of a non-shielding material, so that, for example, wireless transmission from the electronic unit 17 to the environment is possible.

[0026] Furthermore, the figure shows three variants of different base discs 7a, 7b, and 7c. Base disc 7a has a greater axial thickness. Base disc 7b has radially circumferential grooves or recesses milled into it. Base disc 7c has an axial thickness (A) that increases towards the center of the base disc.

[0027] Reference mark:

[0028] 1 - Railway vehicle fluid damper

[0029] 2 - head end to 1

[0030] 3 - Piston rod

[0031] 4 - Containers

[0032] 5 - Fluid medium

[0033] 6 - bottom end

[0034] 7 - Base plate

[0035] 8 - Screw-in sleeve

[0036] 9 - Collar

[0037] 10 - Step heel

[0038] 11 - Outer shell surface

[0039] 12 - Seal

[0040] 13 - Front

[0041] 14 - Inner surface area to 4

[0042] 15 - Bottom side

[0043] 16 - Sensor element

[0044] 17 - Electronic unit

[0045] 18 - Interior

[0046] 19 - Lid

[0047] 20 - Seal

[0048] A - Axial direction

[0049] U - surroundings

[0050] R - Radial direction

Claims

Patent claims 1. Railway vehicle fluid damper (1) comprising a container in which a guide bearing is arranged at the head end and a piston which, with a piston rod (3) extending through the guide bearing, can be inserted into the container (4) with a plate-shaped head, wherein a fluid medium (7) under static preload is arranged in the container (4), characterized in that a bottom disk (7) is inserted in the container (4), wherein the bottom disk (7) is adapted with its outer diameter to the inner diameter of the container (4) and forms the bottom of the container, wherein the bottom disk (7) is spaced from a bottom end (6) of the container (4) by means of a screw-in sleeve (8) and a sensor element (16) is coupled to the bottom disk (7) on the side facing away from the fluid medium (5).

2. Railway vehicle fluid damper (1) according to claim 1, characterized in that the bottom disk (7) has an edge projecting towards the fluid medium (5), wherein the edge is spaced inwards from an inner wall of the housing.

3. Railway vehicle fluid damper (1) according to claim 1 or 2, characterized in that a seal (12) is arranged between the edge and the inner wall of the housing, wherein the pressure of the fluid medium (5) is applied to the end face of the seal (12).

4. Railway vehicle fluid damper (1) according to one of the preceding claims, characterized in that the preload of the fluid medium (5) can be adjusted by the screw-in depth of the screw-in sleeve (8).

5. Railway vehicle fluid damper (1) according to one of the preceding claims, characterized in that the screw-in sleeve (8) is closed at the bottom end (6) by a cover (19).

6. Railway vehicle fluid damper (1) according to one of the preceding claims, characterized in that in the screw-in sleeve (8) an electronic unit (17) is arranged, in particular a transmitting and / or receiving unit.

7. Railway vehicle fluid damper (1) according to one of the preceding claims, characterized in that the cover (19) of the screw-in sleeve (8) is not designed to shield wireless signals.

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