RAIL BRAKE DAMPER

Abstract

A rail brake damper includes a cylinder-piston arrangement. A damping device assigned to the piston comprises at least one damping valve having at least one piston channel, which passes through the piston, connecting the two operating chambers of the cylinder, and a closure element assigned to the piston channel. The closure element is spring pre-loaded with the effect of closing the piston channel and is acted on by the hydraulic pressure which prevails in the operating chamber facing away from the piston rod with the effect of opening the damping valve.

Claims

1. A rail brake damper comprising a cylinder-piston arrangement having a cylinder, a piston that is guided in the cylinder in an axially movable manner and divides the inner chamber of the cylinder into two working chambers, a piston rod connected to the piston and guided out of the cylinder at one end thereof in a sealed manner, an ejector arrangement, which acts on the piston in such a manner as to slide the piston rod out of the cylinder, and a damping device associated with the piston, wherein the damping device comprises at least one damping valve having at least one piston channel which passes through the piston, thereby connecting the two working chambers, and at least one closure element associated with the at least one piston channel, the at least one closure element being spring-biased in such a manner as to close the at least one piston channel, and hydraulic pressure active in the working chamber remote from the piston rod acting on said at least one closure element in such a manner as to open the damping valve.

2. The rail brake damper according to claim 1, wherein the at least one closure element is spring-biased by at least one separate valve-biasing spring in such a manner as to close the at least one piston channel.

3. The rail brake damper according to claim 1, wherein the at least one closure element is formed as a ball, a frustum of a cone, a cone, a sealing disc or a valve spool.

4. The rail brake damper to claim 1, wherein the at least one closure element is made of metal or plastic.

5. The rail brake damper according to claim 1, wherein the at least one piston channel includes a plurality of piston channels connecting the working chambers that pass through the piston and each is associated with a separate closure element, the closure elements being associated with a common support plate, on which the valve-biasing spring acts.

6. The rail brake damper according to claim 2, wherein the at least one valve-biasing spring is supported against an element that is operatively connected to the piston rod.

7. The rail brake damper according to claim 6, wherein an end, remote from the valve-biasing spring, of the element connected to the piston rod is configured to engage with a limit stop spring.

8. The rail brake damper according to claim 1, wherein, adjacently to an end of the cylinder at which the piston rod exits the cylinder, an insert element is arranged in the working chamber close to the piston rod.

9. The rail brake damper according to claim 1, wherein the damping device comprises at least one additional damping valve having at least one additional piston channel, which passes through the piston in such a manner as to connect the two working chambers, and at least one additional closure element associated with the additional piston channel, the at least one additional closure element being spring-biased by at least one additional valve-biasing spring in such a manner as to close the at least one additional piston channel, and the hydraulic pressure active in the working chamber through which the piston rod passes acting on said element in such a manner as to open the at least one additional damping valve.

10. The rail brake damper according to claim 9, wherein the at least one additional piston channel includes a plurality of additional piston channels connecting the working chambers that pass through the piston and each is associated with a separate additional closure element, the additional closure elements being associated with an additional common support plate on which the additional valve-biasing spring acts.

11. The rail brake damper according to claim 9, wherein the additional valve-biasing spring is supported against an element that is operatively connected to a portion of the piston rod that passes through the piston.

12. The rail brake damper according to claim 1, wherein the ejector arrangement comprises at least one ejector spring arranged in the working chamber remote from the piston rod, and/or at least one compressed-gas volume.

13. The rail brake damper according to claim 1, wherein the cylinder is formed having cooling ribs on its outer surface.

14. The rail brake damper according to claim 1, wherein the cylinder-piston arrangement is received in a housing that comprises a bottom part associated with the cylinder, and a cover part that is associated with the piston rod and is displaceable relative to the bottom part.

15. The rail brake damper according to claim 1, wherein the damping device comprises a damping-force reduction device associated with the at least one damping valve configured to reduce the damping force of the at least one damping valve when the temperature of the rail brake damper increases.

16. The rail brake damper according to claim 9, wherein the damping device comprises a damping-force increasing device associated with the at least one additional damping valve configured to increase the damping force of the at least one additional damping valve when the temperature of the rail brake damper increases.

17. The rail brake damper according to claim 1, wherein said damper comprises a locking apparatus configured to hold a unit formed by the piston and piston rod in a state in which the piston rod is inserted into the cylinder.

18. The rail brake damper according to claim 15, wherein the damping-force reduction device associated with the at least one damping valve and/or the damping-force increasing device associated with the at least one additional damping valve and/or the locking apparatus comprises an adjustment apparatus that adjusts automatically when the temperature changes.

19. The rail brake damper according to claim 15, wherein the damping-force reduction device associated with the at least one damping valve and/or the damping-force increasing device associated with the at least one additional damping valve and/or the locking apparatus comprises an adjustment apparatus that can be actuated electrically and/or in a motorised manner and/or electromagnetically and/or pneumatically and/or hydraulically.

Description

[0041] The invention will be described in more detail hereinafter on the basis of an embodiment with reference to the accompanying drawings, in which:

[0042] FIG. 1 is a schematic view of a rail brake damper according to the invention arranged in a track bed;

[0043] FIG. 2 is sectional view of the rail brake damper according to the invention;

[0044] FIG. 3 is an enlarged sectional view of a detail from FIG. 2;

[0045] FIGS. 4a and 4b are sectional views of the rail brake damper according to the invention, showing different embodiments of ancillary apparatuses for preventing the rail brake damper from overheating.

[0046] FIG. 1 generally denotes a rail brake damper according to the invention by 100. The rail brake damper 100 comprises a housing 102 having a bottom part 104 and a cover part 106 that is linearly displaceable relative to the bottom part 104. In the housing 102, a cylinder-piston arrangement 108 is housed, comprising a cylinder 110, which is operatively connected to the bottom part 104, and a piston rod 112, which is operatively connected to the cover part 106.

[0047] The rail brake damper 100 is arranged in a track bed 200. In particular, it is possible to see a rail 204 laid in the track bed 200 by means of a sleeper 202. FIG. 1 also shows a wheel 206 of a wagon (not shown), the wheel rim 208 of which acts directly on the rail brake damper 100.

[0048] The structure of the cylinder-piston arrangement 108 will now be described in detail with reference to FIGS. 2 and 3:

[0049] In the inner chamber of the cylinder 110, a piston 114 is received so as to be displaceable in the longitudinal direction L of the cylinder 110. The piston rod 112 attached to the piston 114 exits the cylinder 110 at the upper end 110a thereof in FIG. 2. In the process, the piston rod 112 is guided in the cylinder 110 by means of a guiding and sealing unit 116.

[0050] Two helical compression springs 118 and 120 act on the piston 114 on the side of the piston 114 remote from the piston rod 112, such that the free end of the piston rod 112 protrudes out of the cylinder 110 when in an initial state not influenced by external forces. This initial state is shown in FIG. 2.

[0051] Above the piston 114 in FIG. 2, a support plate 122 is provided, which is biased towards the valve balls 126a of ball valves 126 (only one shown in FIG. 2) by means of a spring assembly 124. The ball valves 126 are used to close through-openings 128 in the piston 114, which pass through the piston 114 in the longitudinal direction L. Due to the valve balls 126a, there is always a predetermined minimum distance between the piston 114 and the support plate 122.

[0052] At its upper end, the spring assembly 124 is supported against a sleeve 130, which is connected to the piston rod 112 by crimping.

[0053] Below the piston 114 in FIG. 2, a support plate 132 is provided, which is biased towards the valve balls 136a of additional ball valves 136 (only one shown in FIG. 2) by means of a helical compression spring 134. The additional ball valves 136 are used to close through-openings 138 in the piston 114, which pass through the piston 114 in the longitudinal direction L. Due to the valve balls 136a, there is always a predetermined minimum distance between the piston 114 and the support plate 132.

[0054] At its lower end, the helical compression spring 134 is supported against an end element 140, which is operatively connected, by means of a nut 142, to a portion 112a of the piston rod 112 that passes through the piston 114.

[0055] If a wagon collides slowly with the free end of the piston rod 112 or of the cover part 106 and attempts to push the piston 114 into the cylinder 110, the ball valve 136 closes the through-opening 138 in the piston 114 whilst the ball valve 126 tends to open the through-opening 128. However, the valve plate 122, which holds the valve ball 126a on the valve seat of the ball valve 126 under the influence of the spring assembly 124, prevents the through-opening 128 from being opened. The closure force of the spring assembly 124 is selected such that the valve plate 122 is lifted off the piston 114 when a predetermined force, which is still smaller than the force that would cause the wagon to derail, is applied to the piston rod 112. After the ball valve 126 has been opened, hydraulic fluid can flow from the lower working chamber 144, through the clear holes 128 in the piston 114 and into the upper working chamber 146, such that the piston 114 is moved into the cylinder 110. Due to the slow movement of the wagon, the piston 114 is also moved into the cylinder 110 slowly, and so it is sufficient to only slightly lift the valve ball 126a off the piston 114. The result is a small opening cross section, meaning that the damper applies a predetermined damping force counter to the movement of the wagon.

[0056] If the wagon has passed the damper 100, and so no force is applied to the free end of the piston rod 112 again, the helical compression springs 118 and 120 push the piston 114 upwards again into the initial position shown in FIG. 2. In the process, the hydraulic fluid can flow from the upper working chamber 146, past the support plate 122, into the through-openings 138 in the piston 114 and into the lower working chamber 144 while opening the ball valves 136.

[0057] If a wagon collides quickly with the free end of the piston rod 112, the force required to open the ball valve 126 is reached more rapidly due to the greater dynamics, and so the blocked state does not occur or only occurs for a short time and the retraction of the piston rod 112 or piston 114 into the cylinder 110 is damped by the spring assembly 124 in cooperation with the valve plate 122. Due to the greater dynamics, the valve ball 126a is lifted off the piston 114 to an extent corresponding to such dynamics. Overall, an opening cross section that is dependent on the speed of the wagon is produced, and specifically such that the damping force is substantially independent of the speed. In this way, the maximum possible amount of kinetic energy can always be taken away from the wagon regardless of its speed.

[0058] If the wagon has passed the shock absorber, the free end of the piston rod 112 is extended out under the action of the helical compression springs 118 and 120.

[0059] In this case, the ball valve 126 closes the through-opening 128 in the piston 114 under the action of the spring assembly 124 whilst the ball valve 136 tends to open the through-opening 138. In practice, the ball valves 136 are not prevented from opening at all since the helical compression spring 134 is considerably weaker than the helical compression springs 118 and 120. After the ball valves 136 have been opened, hydraulic fluid can flow from the upper working chamber 146, through the clear holes 138 in the piston 114 and into the lower working chamber 144, such that the piston 114 is moved upwards. In the process, the damping provided by the helical compression spring 134 is selected such that the operational readiness of the rail brake damper 100 is restored as quickly as possible, but also such that the impact energy of the piston 114 and piston rod 112 on the upper end of the cylinder 110 is limited to a value that does not pose any risk of damage to the cylinder-piston arrangement 108.

[0060] In addition, at the upper end of the cylinder 110 a limit stop spring 150 is provided, which, in the embodiment shown, is also formed by a disc spring assembly like the spring assembly 124. When the piston rod 112 is being extended, said limit stop spring 150 interacts with the sleeve 130 operatively arranged on said piston rod.

[0061] In addition, an insert element 152 is arranged in the cylinder 110 adjacently to the upper end thereof, in which element there is a gas-filled equalisation space 154 used to hold the volume of hydraulic fluid displaced by the piston rod 112 as it moves into the cylinder 110. The lower end 152a of the insert element 152 in FIG. 2 surrounds the piston rod 112, or the sleeve 130 connected thereto, leaving a narrow gap 156. In this way, the lower end 152a of the insert element 152 keeps turbulent flows of hydraulic fluid, caused the piston 114 moving into the cylinder 110, away from the equalisation space 154 and thus prevents the hydraulic fluid from foaming at the gas-hydraulic fluid boundary.

[0062] It should be added that cooling ribs 158 are also provided on the outside of the cylinder 110 and that at least one opening 160 is provided in a lower boundary surface 104a of the bottom part 104. The air in the housing 102 can be driven out through said opening 160 when the cover part 106 is retracted into the bottom part 104, and fresh air can be sucked into the housing 102 when the cover part 106 extends out again. As a result, an air flow that moves past the cooling ribs 158 of the cylinder 110 is formed in the housing 102, thus ensuring effective cooling of the cylinder-piston arrangement 108.

[0063] To prevent the rail brake damper 100 from overheating as a result of a high number of activations in a short time, e.g. by the wagons being moved off a track by a shunting locomotive, various ancillary measures can be taken, which will be explained in more detail below with reference to FIGS. 1, 4a and 4b. In general, these may be the following: locking apparatuses 310 (see FIG. 1) and 320 (see FIG. 4a) which hold the piston rod 112 in its retracted state, damping-force reduction devices 330, 340 (see FIG. 4a) and 360, 370 (see FIG. 4b) associated with the at least one damping valve 126 and/or damping-force increasing devices 350 associated with the at least one additional damping valve 136 (see FIG. 4a).

[0064] At this juncture, it should be noted that these ancillary apparatuses can of course be used in various combinations with one another, despite being explained below in isolation, i.e. separately from one another, in terms of design and function.

[0065] The locking apparatus 310 according to FIG. 1 is designed to hold the piston rod 112, and thus the cover part 106 actuated by the wheel rim 208, in a retracted state such that no further activation processes of the rail brake damper 100 can take place. For this purpose, an annular groove 312 can be provided on the cover part 106 and used to latch a locking element 314. When the locking apparatus 310 is an activated state, the locking element 314 preferably abuts the cover part 106 in a spring-biased manner such that, when the piston rod 112 moves in the manner of a deflection, said element latches to the annular groove 312 when the groove reaches the appropriate position. As a result, a subsequent rebound of the piston rod 112 and thus of the cover part 106 is blocked until such time as the locking element 314 of the locking apparatus 310 moves back out of the annular groove 312 under the action of a control apparatus (not shown) and the movement of the cover part 106 is released again.

[0066] FIG. 4a shows another design variant of a locking apparatus of this kind. The locking apparatus 320 comprises an axial actuator 322, which can be formed as an actuating magnet, for example. The locking apparatus 320 further comprises a coupling element 324 that is connected to the end element 140 in an axially fixed manner and can be operatively connected to the axial actuator 322. If the piston rod 112 is in a retracted state, a frictional connection between the axial actuator 322 and the coupling element 324 is established by the axial actuator 322 being actuated by, for example, an external control unit (not shown), such that an extension movement of the piston rod 112 under the action of the helical compression springs 118 and 120 is prevented until such time as the frictional connection between the axial actuator 322 and coupling element 324 is undone again and the extension movement of the piston rod 112 is thus released in turn.

[0067] In addition, FIG. 4a shows a damping-force reduction device 330 associated with the at least one damping valve 126. The damping-force reduction device 330 comprises a ring motor 332, which is arranged in the region of the upper working chamber 146. In this case, the ring motor 332 can be actuated by, for example, an external control unit (not shown).

[0068] Furthermore, a threaded spindle 334 driven by the ring motor is provided and is displaceable axially along the main axis of the piston rod 112. The ring motor 332 is axially secured to the side facing away from the threaded spindle 334 by means of a sleeve 336 operatively connected to the piston rod 112. The threaded spindle 334 is operatively connected to the spring assembly 124 such that axially displacing the threaded spindle 334 along the main axis of the piston rod 112 can adjust, i.e. increase or decrease, the bias of the spring assembly 124 in a targeted manner. Lastly, due to the adjustability of bias of the spring assembly 124, the opening behaviour of the ball valve 126 and thus the damping force of the rail brake damper 100 in the manner of the deflection can be controlled in a targeted manner by means of the support plate 122. If the bias of the spring assembly 124 is selected to be very low, for example, there is only a very low damping force of the rail brake damper 100 in the manner of a deflection, which results in lower energy dissipation and thus lesser heating of the rail brake damper 100 even in the event of repeated activation processes in a short time.

[0069] Another possible embodiment, shown in FIG. 4a, of a damping-force reduction device 340 comprises an actively connectable bypass 342 towards a buffer container 344 (not shown) arranged outside the cylinder-piston arrangement 108. In this respect, the connection, i.e. the opening of the bypass 342, can be controlled, for example, by an external control device (not shown), which opens a valve 344 that can be actuated electrically and/or in a motorised manner and/or electromagnetically and/or pneumatically and/or hydraulically. When the bypass 342 towards the buffer container is in a connected or activated state, only a negligible hydraulic pressure is built up in the lower working chamber 144 when the piston moves 114 in the manner of a deflection, and so only a negligible damping action of the rail brake damper 100 occurs. In turn, this effect leads to lower energy dissipation and thus lesser heating of the rail brake damper 100.

[0070] Lastly, the rail brake damper 100 shown in FIG. 4a can additionally or alternatively comprise a damping-force increasing device 350, which is arranged in the region of the through-opening 138 in the piston 114, which opening is associated with the additional ball valve 136. For this purpose, a temperature-sensitive throttle 352, designed for example as an annular expansion wax cartridge or a shape-memory metal element, can be provided in the through-opening 138. When the rail brake damper 100 heats up due to a large number of activations, the temperature-sensitive throttle 352 expands and thus narrows the cross-sectional area available for the hydraulic fluid through the through-opening 138; as a result, only a relatively small amount of hydraulic fluid, or even no hydraulic fluid at all, can flow through the through-opening 138, thereby slowing down or even completely preventing a movement of the piston 114 in the manner of a rebound. Moreover, it is also possible to provide, additionally or alternatively, a temperature-sensitive helical compression spring 354 (e.g. a shape-memory metal spring) that replaces the helical compression spring 134 and axially expands when the temperature rises, thus increasing the force transmitted by the support plate 132 to the additional ball valve 136 in the manner of the closure. The effect of slowing down or preventing the piston 114 from extending out as the temperature rises can thus be achieved and/or heightened further. As a result, the heating up of the rail brake damper 100 can likewise be limited, thereby preventing damage due to thermal effects.

[0071] A temperature-sensitive valve element of this kind can also be used in the damping-force reduction device 340 instead of the valve element 344. FIG. 4b shows a damping-force reduction device 360 formed in this manner. In this device, the bypass 362 to the buffer container (not shown) is connected by means of the temperature-sensitive valve 364, which opens automatically when a predetermined temperature is reached, meaning that no energy and/or control signals have to be supplied.

[0072] FIG. 4b also shows a further embodiment of a damping-force reduction device 370. In this case, the damping-force reduction device 370 comprises a shape-memory metal sleeve 372, which is axially secured to the side facing away from the piston 114 by means of a sleeve 374 operatively connected to the piston rod 112. An expansion wax cartridge 376 is also provided, which expands axially along the main axis of the piston rod 112 as the temperature rises. The expansion wax cartridge 376 is operatively connected to the spring assembly 124. By the expansion wax cartridge 376 expanding due to a temperature rise, the bias of the spring assembly 124 can thus be reduced in a targeted manner, which ultimately leads to a reduced opening force of the ball valve 126. Consequently, the damping force of the rail brake damper 100 in the manner of the deflection is reduced automatically as the temperature increases, without any external control device, which ultimately leads to a merely negligible damping force of the rail brake damper 100 and ultimately constitutes a further option for preventing the rail brake damper 100 from heating up as a result of operation. Likewise, the bias of the spring assembly 124 increases again as the temperature drops, which leads to reinforcement of the damping function of the rail brake damper 100 and thus to its automatic reactivation.