DE102021108106A1 - Rail vehicle fluid damper with sensor and method for monitoring it - Google Patents

Abstract

The present invention relates to a rail vehicle fluid damper and a method for monitoring it, wherein a reference piece (9) is arranged inside a housing (2) of the damper (1) and the deformation of the reference piece (9) is measured and a conclusion about the pressure change and thus pressure monitoring of the fluid medium (7) in the housing (2) can be carried out.

Description

The application relates to a rail vehicle fluid damper with the features in the preamble of claim 1.

The present invention further relates to a method for monitoring the pressure in a rail vehicle fluid damper according to the features in claim 10.

According to the prior art, it is known to attach dampers to the front or end of rail vehicles, so that when two rail vehicles are coupled, the rail vehicles weighing several tons can be struck without being destroyed. For this purpose, dampers are arranged, which absorb and dampen the forces arising in the event of a light impact of a rail vehicle on another rail vehicle. Such dampers are also called buffers.

Another task of such dampers, depending on the design of the couplings formed between two rail vehicles, can be to maintain the distance between two rail vehicles that changes dynamically during operation. This occurs in particular when cornering and/or at different heights. In this regard, it is also known that the dampers are prestressed and therefore also have spring properties.

A generic damper is, for example, from DE 20 2019 102 118 U1 known.

In long-term operation, such a damper can be subject to signs of wear and tear. The damping properties can also differ due to different climatic conditions, in particular strong temperature fluctuations with a temperature delta of more than 30 ° C.

It is therefore the object of the present invention to provide a way of monitoring such a damper during operation in a simple, as trouble-free as possible and inexpensive manner.

According to the invention, the aforementioned object is achieved in a rail vehicle fluid damper with the features in claim 1 .

A procedural part of the task is solved with the features in claim 10 .

Advantageous design variants are described in the dependent claims.

The rail vehicle fluid damper has an inner container in which a guide bearing is arranged at the head. The container is in particular of cylindrical design. Furthermore, the rail vehicle fluid damper has a piston which is coupled to a piston rod. The piston rod reaches through the guide bearing and the piston itself has a plate-shaped head with which it can be moved into the container. In the container itself there is a fluid medium which is under static prestress and which is present in particular in the liquid state of aggregation.

According to the invention, the rail vehicle fluid damper is characterized in that a reference piece that is in direct contact with the fluid medium is arranged in the container. The reference piece is particularly preferably arranged in a floating manner in the container. A sensor is coupled to or on the reference piece itself in such a way that the pressure of the fluid medium can be measured.

A change in pressure, either when the damper is not in use due to a change in the external climatic conditions, in particular the temperature, and/or a change in pressure due to dynamic loads during operation of the damper, also affects the pressure change on the container, the piston and the seals off. Due to the fact that the reference piece is in direct contact with the fluid medium, the change in pressure of the fluid medium also causes a respective change in shape of the reference piece. According to the invention, the change in shape of the reference piece is measured by the sensor. The reference piece itself is calibrated and/or configured in terms of its geometric dimensions in such a way that, according to a conversion formula and/or a stored matrix, it uses the measured values of the change in shape of the reference piece via a conversion formula and/or a stored matrix to draw conclusions about the pressure and thus the condition of the entire damper, in particular the housing and/or the seals of the damper.

This application is particularly suitable for dampers in rail vehicles that are used as so-called clutch dampers during operation. However, rail vehicles also have dampers that are used as impact absorbers. These are arranged at the front or end and installed in a manner comparable to the principle of a bumper in motor vehicles. Typically, such impact absorbers have the sole purpose of reducing the impact in the event of an impact and reducing the crash energy that occurs as a result of retracting the impact absorber. Especially at The present monitoring method is particularly useful for such impact dampers, since the impact dampers sometimes do not experience any operation for years, but the pressure state in the damper can always be measured without a doubt using the measuring method according to the invention.

For this purpose, the sensor is in particular a strain gauge. A piezoelectronic sensor can also be used as an alternative to the strain gauge. Such a piezoelectronic sensor is particularly suitable for use in a hollow body.

The reference piece is very particularly preferably a reference disk. In the case of a container which is in particular of cylindrical design, the reference piece can thus very particularly preferably be arranged on the bottom side in the container.

The sensor itself is also preferably arranged on a pressure-remote side of the reference piece. The reference piece also particularly preferably has a seal coupled to it. For this purpose, in particular, the sensor is arranged on the reference piece on the side facing away from the pressure, such that the sensor is not in contact with the fluid medium. Both the sensor itself, which is in particular a strain gauge, and lines coupled to the sensor, as well as any integrated sensor electronics and/or energy source of the sensor, are therefore themselves not exposed to the pressure of the fluid medium.

The reference piece is also particularly preferably held in a form-fitting manner, but in at least one degree of freedom in a floating manner in the housing. For this purpose, a stop is also preferably provided in the container, with a support screw facing away from the pressure side then enclosing the reference piece between the stop or holder and the support screw in a form-fitting manner. In a particularly preferred manner, the reference piece can then also have a plurality of seals.

Furthermore, particularly preferably, the reference piece can have a depression or a recess on its pressure-facing side. The change in shape of the reference piece when the pressure of the fluid medium changes can thus be recorded in a reference-safe manner.

An advantage that is essential to the invention is that twisting of the housing or other influences have no or negligible effects on the measurement of the pressure prevailing in the container, since the reference piece is arranged in the container and not on the outside of the container.

A second significant advantage is the fact that despite the fluid medium and a correspondingly high pressure that occurs, the sensor technology allows direct measurement in almost immediate contact with the pressure medium.

For example, the damper has an initial static force of the pressurized fluid medium when the piston begins to depress of at least 100 kN.

The present invention further relates to a method for performing pressure monitoring in a rail vehicle fluid damper. According to the invention, the method is characterized in that a change in pressure causes a change in the shape of the reference piece, with the change in shape of the reference piece being detected by the sensor and the pressure being evaluated or converted via sensor electronics.

The sensor electronics can be integrated into the sensor itself. However, it can also be positioned separately, for example by cable, on or from the damper. The sensor electronics itself can then send signals, for example also wirelessly, to a control station. A measured value can also be recorded at predetermined intervals in an extremely energy-saving manner. A respective sensor can then be checked or the data can be read out with an evaluation unit.

• 1 und 2a und b eine Längsschnittansicht sowie eine Detailansicht einer ersten Ausgestaltungsvariante eines erfindungsgemäßen Referenzstückes mit Sensor im Boden eines Dämpfers,
• 3 und 4 eine zweite Ausgestaltungsvariante mit Referenzstück im Bereich des Führungslagers,
• 5 und 6 eine dritte Ausführungsvariante mit Referenzstück im tellerförmigen Kopf des Kolbens,
• 7 und 8 eine vierte Ausgestaltungsvariante des erfindungsgemäßen Fluiddämpfers und
• 9 und 10 eine fünfte Ausgestaltungsvariante des Fluiddämpfers mit einem Hohlkörper im Boden des Dämpfers.

Further advantages, features, properties, aspects of the present invention are the subject of the following description. Preferred design variants are shown in schematic figures. These serve for a simple understanding of the invention. Show it:

• 1 and 2a and b a longitudinal sectional view and a detailed view of a first embodiment variant of a reference piece according to the invention with a sensor in the bottom of a damper,
• 3 and 4 a second variant with a reference piece in the area of the guide bearing,
• 5 and 6 a third variant with a reference piece in the plate-shaped head of the piston,
• 7 and 8th a fourth embodiment variant of the fluid damper according to the invention and
• 9 and 10 a fifth embodiment of the fluid damper with a hollow body in the bottom of the damper.

In the figures, the same reference numbers are used for the same or similar components, even if a repeated description is omitted for reasons of simplification.

1 shows a rail vehicle fluid damper 1 according to the invention, having a housing 2 and a piston 3 moving into the housing 2. The piston 3 itself has a piston rod 4 and a plate-shaped head 5. The piston 3 is connected via a guide bearing 6, for example in the form of a screw-in guide bearing 6 coupled in the housing 2 or in an interior of the housing 2 is a fluid medium 7, which is statically prestressed, is arranged. If the piston 3 now moves into the housing 2 in order to carry out a damping process, the pressure of the fluid medium 7 changes.

According to the invention, a reference piece 9 in the form of a reference disk 9 is arranged in a base 8 of the housing. The reference disk 9 is in direct contact with the fluid medium 7. On the side facing away from the pressure, the reference disk 9 is pressed against an underside of the base 8 by a support screw 10, with the reference disk 9 being mounted essentially in a floating manner, in particular floating in its radial direction R , is trained. A pressure change in the fluid medium 7 thus acts directly on the reference disk 9 and causes a change in shape of the reference disk 9. An enlarged representation shows 2 . The fluid medium 7 is thus in direct contact with the reference disk 9 through a passage 11 in the bottom 8 of the housing 2. The reference disk 9 has a depression 12 on its pressure-facing side. Furthermore, respective seals 14, in particular in the form of O-rings, are arranged. A radially circumferential seal 14 can also be additionally provided. A sensor 15, in particular in the form of a strain gauge (DMS), is arranged on the side facing away from the pressure, ie on the back. This is coupled to sensor electronics 17 via a cable 16 . The sensor electronics 17 can also be an energy source or a wireless sensor or, for example, a wired connection in the form of a USB connection or other data readout option.

The principle can in particular at the 2a to be understood again. A pressure change in the fluid medium 7 simultaneously leads to a change in shape, albeit only a slight one, of the reference piece 9. The sensor 15 on the reference piece 9 can then measure the change in shape of the reference piece 9 itself. He passes this on to the sensor electronics 17, where, for example, the measured values can be stored or they can be passed on to a further external evaluation unit.

2 B shows the force acting on the reference disk 9 in a greatly exaggerated manner. The force F results from the formula pressure times area and leads to a deformation of the reference disk 9. The strain gauge arranged on the back of the reference disk 9 also undergoes a deformation or change in length due to the greatly exaggerated deformation of the reference disk 9. It is thus possible to use a mathematical conversion formula, a stored characteristic curve or a stored matrix to convert the measured deformation of the reference disk 9 in order to draw conclusions about the pressure prevailing in the damper 1. As an example on the reference disc 9 according to 2 B described, but can be used for all design variants of the invention described in this document, the reference disk 9 is produced in particular from a metallic material, in particular from a steel material. This is in particular a stainless steel alloy, for example (1.4021 - X 20 Cr 13). However, the reference disc 9 can also be made of a heat-treated steel, for example 1.6580-30 CrNiMo 8. The selection of the material depends in particular on the material of the damper 1 housing. For this purpose, it is particularly advantageous to select such that in the required pressure range and the associated deformations in the reference disk 9 it is exclusively an elastic deformation, so that the pressures acting on the reference disk 9 do not cause plastic deformation. In particular, the reference disc 9 should either be made of the same material as the housing. Alternatively, the reference disc should have a tensile strength Rm of at least 80 to 90 percent of the tensile strength Rm of the housing material. Thus, the requirement of elastic deformation can be secured.

It is also possible to use a "universal" reference disk 9 . This offers the advantage that the reference disc 9 has to be calibrated once. This one universal reference disc 9 can then be used for different damper types and also for different housing materials via a mathematical conversion formula stored there, a characteristic curve or characteristic diagram or also a stored matrix. For this purpose, a pressure range of up to 4000 bar that occurs in practice is covered by the universal reference disk 9 . Depending on the housing type and housing material, this can then be used via the respective conversion and the pressure that actually occurs can be measured. This reduces the construction costs per damper 1 with the inventive ßen monitoring electronics. As a minimum evaluation, at least a target/actual comparison of the measurement data is stored, so that a conclusion can be drawn as to the operating status "okay" or "not ok".

With refined evaluations, other states can also be identified, such as e.g. B. the intermediate status "can still be used until...". With the appropriate linking of the data and suitable analysis tools, it is then also possible for the operating status to be forecast as a function of the number of operating hours or the running distance.

In connection with operational monitoring, there are also advantages for reducing operating costs. Was it previously necessary - due to the lack of real-time condition monitoring facilities - to carry out so-called "preventive maintenance", i. H. the dampers were sent for service in relation to their service life, whether it was actually required or not, i. i.e. Usually after 5 years, the permanent status monitoring opens up the more cost-effective procedure of only having the dampers serviced when necessary. This automatically lowers operating costs.

Parallel to these safety aspects, the operating data can also be analyzed in more detail. Extensive recordings of the system behavior, e.g. how often the damper was started, what are the operating conditions over the course of the route, working frequency of the buffer, etc.. Here again, the compression values recorded in sensor electronics can be adjusted or upgraded in practice, after which a detailed The damper is evaluated. This can be done manually afterwards, but also automatically, so that the sensor electronics are designed to be self-learning and then in turn store more detailed analysis data.

All in all, the monitoring system provides insights that are becoming increasingly important, especially for operation with automatic railways - as well as the driverless railway systems that are being used more and more frequently. It must be possible for systems to control themselves in order to avoid serious errors for people and technology. Our system is ideally suited for this.

3 and 4 show a second embodiment of the present invention. In this case, the damper 1 is also in turn designed with a container. Here, too, the reference piece 9 itself is arranged on the bottom side, with the reference piece 9 being particularly recognizable according to FIG 4 into the guide bearing 6 of the container 2. The reference piece 9 is in contact with the fluid medium 7 via a channel 18, so that in turn a change in the pressure of the fluid medium 7 leads to a deformation of the reference piece 9.

5 and 6 show a third embodiment of the present invention. A damper 1 with a housing 2 is also formed here. The reference piece 9 is also arranged in the housing 2 here, but not in direct contact with the housing, but in the plate-shaped head 5 of the piston 3. The enlarged view according to FIG 6 shows that here the plate-shaped head 5 of the piston 3 is designed in two parts, such that a floating mounting of the reference piece 9 is possible. A part of the plate-shaped head 5 thus serves as a support screw 10 and a front part 19 of the head 5 serves as a counter bearing or abutment. Here, too, the reference piece 9 is kept floating within the head 5. The sensor electronics 17 are coupled to an evaluation unit via a cable 16 .

7 and 8th show a further embodiment variant of the present invention. Essentially, this is analogous to the design variant with regard to the placement and the basic structure of the container of the damper 1 1 and 2 . The difference, however, lies in a special manufacturing feature. For this purpose, a holding body 20 is formed, which is arranged on the bottom side in the container. The reference piece 9 is then placed in the holding body 20 analogously to the principle of the embodiment variant in FIG 1 and 2 . However, the manufacturing technology of the container is advantageous here, since the container itself weighs up to several kilograms and has to be machined in a complex manner. A through hole 21 can first be made here, in which the holding body 20 and the support screw 10 are then arranged. The holding body 20 can have a T-shaped cross section, as shown, and can rest on the pressure inside facing the fluid medium 7 with a stepped shoulder.

9 and 10 show an alternative embodiment variant of the present invention. The developmental structure of the housing 2 of the damper 1 is analogous to 7 and 8th . However, the holding body 20 itself is designed as a hollow body 22 which is designed to engage in the pressure chamber of the fluid medium 7 or the interior of the container. In this way, the sensor 15 itself can be arranged not only on the bottom side, but also on a lateral surface. According to this embodiment variant, the hollow body is thus the reference piece 9 itself. A change in the pressure of the fluid medium 7 also changes the Shape of the hollow body 22, which acts as a reference piece 9. The sensor 15, which according to an inner side of a lateral surface of the hollow body 22 10 is placed, this change in shape can be detected and in turn passed on to sensor electronics 17 .

Reference List

1

mute

2

Housing

3

Pistons

4

piston rod

5

head

6

guide bearing

7

fluid medium

8th

floor

9

Reference piece/reference disc

10

support screw

11

passageway

12

deepening

13

o ring

14

poetry

15

sensor

16

Cable

17

sensor electronics

18

channel

19

front part to 5

20

holding body

21

through hole

22

hollow body

R

radial direction

rm

tensile strenght

f

power

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 202019102118 U1 [0005]

Claims (10)

Rail vehicle fluid damper (1) having a container in which a guide bearing (6) is arranged on the head side and a piston (3) which, with a piston rod (4) passing through the guide bearing (6), can be moved into the container with a plate-shaped head (5). a fluid medium (7) which is under static pretension is arranged in the container, characterized in that a reference piece (9) which is in direct contact with the fluid medium (7) is arranged in the container, with the reference piece (9) a sensor (15) is coupled in such a way that the pressure of the fluid medium (7) can be measured. Rail vehicle fluid damper (1) according to claim 1 , characterized in that the reference piece (9) is a reference disk (9). Rail vehicle fluid damper (1) according to claim 1 or 2 , characterized in that the reference piece (9) is floating. Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the reference piece (9) is arranged on the bottom side in the container, the container being in particular of cylindrical design. Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the sensor (15) is a strain gauge or a piezoelectric sensor. Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the sensor (15) is arranged on a pressure-remote side of the reference piece (9). Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the reference piece (9) is held by a support screw (10). Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the reference piece (9) has a seal, the seal being arranged on a side facing away from the pressure in such a way that the reference piece (9) comes into contact with the fluid medium (7 ) is in contact. Rail vehicle fluid damper (1) according to one of the preceding claims, characterized in that the reference piece (9) is calibrated. Method for monitoring the pressure in a rail vehicle fluid damper (1) according to the features in claim 1 , characterized in that a change in pressure causes a change in shape of the reference piece (9), the change in shape of the reference piece (9) being detected by the sensor (15) and the pressure being evaluated via sensor electronics (17).

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