Rail vehicle fluid damper with monitoring function

Abstract

The invention relates to a rail 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), can be inserted into the container (4) with a plate-shaped head, passing through the guide bearing, wherein a fluid medium (7) under static prestress is arranged in the container (4), characterized in that a base plate (7) is inserted into a base end (6) of the container (4), wherein the base plate (7) is adapted with its outer diameter to the inner diameter of the sleeve and forms the container base, wherein the base plate (7) is spaced from the base end (6) of the sleeve by means of a screw-in sleeve (8), and a sensor element (16) is coupled to the base plate (7) on the side facing away from the fluid medium (5).

Description

[0001] The present invention relates to a rail vehicle fluid damper according to the features in the preamble of claim 1.

[0002] It is known from the prior art to use dampers on the front or end of rail vehicles so that, during a coupling process, two rail vehicles, each weighing several tons, can be brought into contact with each other without causing damage. These dampers are also called hydrostats and are so-called rail vehicle fluid dampers. The dampers can also be called viscoelastic spring dampers or viscoelastic dampers.

[0003] In the event of a minor collision between a rail vehicle and another rail vehicle, the resulting forces are absorbed and dampened. Dampers can also be called buffers.

[0004] Another function of such dampers, depending on the design of the coupling between two rail vehicles, can be to maintain the dynamically changing distance between them during operation. This is particularly important when cornering and / or when vertically offset. For this purpose, the dampers are also known to be preloaded and thus also possess suspension properties.

[0005] A generic hydrostat is known, for example, from DE 20 2019 102 118 U1.

[0006] Once such a hydrostatic damper is installed, the fluid contained within it, also known as the liquid, is subjected to a preload force. During operation, it is therefore not possible to view inside the damper to draw conclusions about the fluid, the condition of the seals, or the wear or deterioration of the damper.

[0007] DE 10 2021 108 106 A1 discloses a system for monitoring a hydrostatic damper or damper in question. A reference piece, particularly in the form of a reference disc, is installed in a hydrostatic damper. The pressure in the damper, which changes upon compression of the damper, can be measured by deformation of the reference disc.

[0008] The object of the present invention is to demonstrate a possibility of equipping a hydrostatic damper in question with a monitoring function that allows conclusions to be drawn about the state of wear or the actual state within the damper with a simple structural design, but at the same time with an optional permanent evaluation option.

[0009] The above-mentioned object is achieved according to the invention with a rail vehicle fluid damper having the features in claim 1.

[0010] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0011] The present invention relates to a rail vehicle fluid damper. This rail vehicle fluid damper can also be referred to as a hydrostatic damper, viscoelastic damper, or viscoelastic spring within the scope of the invention. In the following, the rail vehicle fluid damper is also referred to as a damper. With a pure spring function, the piston retracts into the housing. This retraction movement increases the pressure in the hydrostatic damper, here functioning as a hydrostatic spring or viscoelastic spring. When the retraction force is removed, the increased pressure then causes the piston to return to its original position, thus extending the piston again. In the case of a damper, a piston is also present, which is virtually gap-free or forms a small gap with respect to the inner wall of the housing.When the piston and piston rod retract into the housing, not only does the pressure of the medium increase, but friction also arises due to the medium flowing past the gap, which then creates the damping effect. A throttle bore may also be present in the piston.

[0012] This damper contains a fluid medium, a viscoelastic fluid. This fluid is stored in the damper under a preload of preferably greater than 300 bar. For this purpose, the damper has a reservoir in which a guide bearing is arranged at the head end. A piston, which extends through the guide bearing with a piston rod, has a plate-shaped head and can be retracted into the reservoir.

[0013] The aforementioned fluid medium is under static preload within the container. As the plate-shaped head is retracted inside the container, the fluid medium is further compressed. This increases the pressure, which can reach up to approximately 4,000 bar. This high internal pressure leads to a marginal, yet measurable, deformation of the container.

[0014] The container wall, but also the container base, change their shape due to the high internal pressure. Based on the measured deformation, it is in turn possible to calculate the amount of internal pressure. For this purpose, it is now provided that a base plate is inserted from one end of the container at the bottom. The base plate has an outer diameter that is adapted to the inner diameter of the sleeve. Preferably, the outer diameter of the base plate essentially corresponds to the inner diameter of the sleeve of the container, which is sleeve-shaped, hereinafter also referred to as a sleeve or container sleeve. The outer diameter of the base plate is designed in particular as a transition fit, preferably as a clearance fit between the outer diameter of the base plate and the inner diameter of the container sleeve.

[0015] The base plate is inserted into the container from one end at the bottom. A screw-in sleeve is also provided to hold the base plate in the container. The screw-in sleeve has an external thread that is screwed into an internal thread of the container sleeve. This distances the base plate from one end at the bottom of the container, thus offsetting the base plate inwardly within the container relative to the direction of the driver's bearing. The position of the base plate can be determined by the depth of engagement of the screw-in sleeve.

[0016] According to the invention, the static preload pressure in the container is adjusted by adjusting the depth of engagement of the screw-in sleeve. By screwing the screw-in sleeve in further, it is possible to increase the compression or pressure on the fluid medium. This represents a further advantage of the invention. Firstly, the pressure can be adjusted. Secondly, the static pressure can be readjusted. For example, after the rail vehicle fluid damper has been in use for several years, the seals and / or fluid medium may have become exhausted to a certain extent. In this case, it is possible to increase the static pressure again by screwing the screw-in sleeve in further. This increases the service life of the rail vehicle fluid damper.However, the monitoring option described later does not reduce operational reliability, since the pressure in the fluid medium can be measured and thus monitored both during static preload and during actuation of the rail vehicle fluid damper.

[0017] Furthermore, a sensor element is arranged on the side of the base plate facing away from the fluid medium. This is, in particular, a strain gauge. When the damper is actuated, the internal pressure increases. As a result, the base plate deforms, or the degree of deformation can be measured, thus allowing the current internal pressure of the damper to be calculated.

[0018] A further advantage is that a hollow space remains on the side of the screw-in sleeve facing away from the base plate. This hollow space can accommodate additional measuring sensors, but also a transmitting and receiving unit or other electronic unit. It is also possible to close the screw-in sleeve at its base end with an additional cover. In particular, this cover also has a seal. This allows the cavity in the screw-in sleeve to be shielded from the environment, in particular to be sealed watertight and / or airtight. The corresponding electronics, but also a transmitting and receiving unit, are thus arranged in a reliable manner, but can be easily accessed for maintenance purposes by unscrewing the cover of the screw-in sleeve, without the damper itself having to be disassembled with a static preload of over 300 bar.

[0019] Furthermore, the housing and the screw-in sleeve are made of metal. The cover of the screw-in sleeve can be made of a non-shielding material, such as a plastic or similar, so that corresponding data can be transmitted to the environment.

[0020] A further design advantage has surprisingly emerged in that the design with a base plate, which has a previously mentioned diameter ratio of the outer diameter of the base plate to the inner diameter of the housing, seals off the fluid medium in the damper in a particularly advantageous manner. For this purpose, the base plate has a shoulder or a protruding edge or collar which projects in the direction of the fluid medium. A gap is formed between the inner surface of the housing and the collar. A seal, in particular an annular seal, is inserted in this gap. One end face of the seal therefore points in the direction of the fluid medium. The pressure acting on the fluid medium then presses on the end face of the seal and thus the seal in the direction of the base plate, but at the same time also on the inner surface of the housing and the outer surface of the stepped shoulder orGap in the base plate. A type of self-sealing action occurs due to the static preload force of the fluid medium. For this purpose, a seal is used, particularly before the damper is filled with the fluid medium or when inserting the base plate, which seal has an interference fit with the inner surface of the housing and the outer surface of the stepped shoulder. This in turn ensures that no fluid medium can penetrate axially between the seal and the base plate. Furthermore, different base plates can be used. The base plates can, for example, be made from different materials and then have a corresponding thickness in the axial direction. A base plate with turned sections can be used, or alternatively, it is also possible to use a base plate with a varying thickness in the axial direction. In particular, the thickness in the axial direction increases towards the center of the plate.Thus, from outside to inside in the radial direction, the thickness of the base plate increases in the axial direction.

[0021] Further advantages, features, 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. The figure shows a rail vehicle fluid damper in longitudinal view with partial section as well as various variants of base plates.

[0022] The embodiments mentioned above and described below can be combined individually with each other as desired without departing from the scope of the invention.

[0023] The figure shows a longitudinal view of a rail vehicle fluid damper 1 according to the invention. This has a piston rod 3 at a head end 2. The piston rod 3 is mounted at the head end 2 in a guide bearing (not shown in detail). The piston rod 3 can be moved into the damper 1 in the axial direction A. A plate-shaped head (also not shown) then compresses the fluid medium 5 located in a container 4 of the damper 1. Initially, the damper 1 is designed with a static preload of preferably more than 300 bar. If the piston rod 3 is moved into the damper 1 in the axial direction A, this pressure and thus the internal pressure or operating pressure increases to up to 4,000 bar. A relatively thick-walled container wall made of metallic material deforms as a result of the strong pressure increase. A base plate 7 is inserted at a base end 6.The base side 15 is arranged at a distance from the bottom end 6 of the container 7. A screw-in sleeve 8 is provided so that the base plate 7 is arranged in the container 4. The screw-in sleeve 8 has an external thread which engages with an internal thread of the sleeve-shaped container. Thus, by varying the screw-in depth in the axial direction A, the position of the base plate 7 in the container 4 can be adjusted. The base plate 7 has a protruding collar 9. This collar 9 creates a stepped shoulder 10 on an outer surface 11 of the base plate 7. A seal 12 in the form of an annular 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 or presses the seal 12 in the axial direction A against the stepped shoulder 10 of the base plate 7. 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 stepped shoulder 10. The fluid medium 5 is thus sealed off from the base plate 7. An outer diameter of the base plate 7 essentially corresponds to the inner diameter 14 of the container 4. Any play is sealed off by the previously described seal 12. A sensor element 16, for example in the form of a strain gauge, is arranged on the base side 15 of the base plate 7 opposite the fluid medium. The sensor element 16 measures a deformation of the base plate 7 in the axial and / or radial direction or stresses occurring in the base plate 7. This can then be used to draw conclusions about the applied pressure of the fluid medium 5. Furthermore, an electronics unit 17, for example as a transmitting and receiving unit, is connected to the sensor element 16.An interior space 18, which is 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 from the environment U. The cover 19 is preferably made of a non-shielding material, so that, for example, wireless transmission from the electronics unit 17 to the environment is enabled.

[0024] Furthermore, the figure shows three variants of different base plates 7a, 7b, and 7c. The figure of the base plate 7a has a greater axial thickness. The figure of the base plate 7b has radially circumferential notches or recesses milled into the base plate. The figure of the base plate 7c shows that the thickness of the base plate 7, formed in the axial direction A, increases toward the center of the base plate 7. Reference symbol: 1 rail vehicle fluid damper 2 head end to 1 3 piston rod 4 containers 5 Fluid medium 6 bottom end 7 base plate 8 screw-in sleeve 9 collars 10 step landing 11 Outer surface 12 Seal 13 Front side 14 inner surface to 4 15 Bottom side 16 Sensor element 17 Electronics unit 18 Interior 19 lids 20 Seal A axial direction U environment R Radial direction

Claims

[1] A rail vehicle fluid damper (1) comprising a container (4) in which a guide bearing is arranged at the head end, and a piston which, with a piston rod (3), can be inserted into the container (4) with a plate-shaped head, passing through the guide bearing, wherein a fluid medium (5) under static prestress is arranged in the container (4), wherein a base plate (7) is inserted into the container (4), wherein the base plate (7) is adapted with its outer diameter to the inner diameter of the container (4) and forms the container base, wherein the base plate (7) is spaced from a base-side end (6) of the container (4) via a screw-in sleeve (8), and wherein a sensor element (16) is coupled to the base plate (7) on the side facing away from the fluid medium (5), characterized by that the preload of the fluid medium (5) can be adjusted by the screw-in depth of the screw-in sleeve (8). [2] Rail vehicle fluid damper (1) according to claim 1, characterized by that the base plate (7) has a collar (9) projecting in the direction of the fluid medium (5), wherein the collar (9) is spaced inwards from an inner wall of the container (4). [3] Rail vehicle fluid damper (1) according to claim 2, characterized by that a seal (12) is arranged between the collar (9) and the inner wall of the container (4), wherein the pressure of the fluid medium (5) is applied to the end face of the seal (12). [4] Rail vehicle fluid damper (1) according to one of the preceding claims, characterized by that the screw-in sleeve (8) is closed at the bottom end (6) by a cover (19). [5] Rail vehicle fluid damper (1) according to one of the preceding claims, characterized by that an electronic unit (17), in particular a transmitting and / or receiving unit, is arranged in the screw-in sleeve (8). [6] Rail vehicle fluid damper (1) according to claim 4, characterized by that the cover (19) of the screw-in sleeve (8) is not designed to shield wireless signals.

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