Control device for compressed-air brakes

[0001] The invention relates to a control device for compressed-air brakes according to the preamble of claim 1.

[0002] Compressed-air brakes are used, for example, in the case of rail vehicles, where the braking operation is initiated by lowering the pressure in a main air pipe. This is provided for safety reasons but means that a control device is required which ensures that, when the pressure is lowered in the main air pipe, a pressure rise takes place in the brake cylinders. Such a control device is described, for example, in European Patent Document EP 0 133 653 B1.

[0003] Because of their complexity, such control devices should have a certain size. As illustrated, for example, in Specification B-EC00.25, Picture 5 and 6, a control sleeve 101.37, a minimum pressure limiting device F and a Ü-monitor U with the Ü-chamber K are provided. These are three structural components which together represent certain constructional expenditures, particularly the position of the control sleeve in the piston rod of the triple-pressure element G influencing the size of the overall control valve. The influence is caused, on the one hand, directly by the size of the control sleeve which has an effect on the height of the housing, but also indirectly because, for operating the control sleeve and overcoming the friction of the sliding sealing caused by the control sleeve, a certain size of the diaphragm disk 101.21 is required.

[0004] It is an object of the invention to provide a control device at reduced expenditures and of a smaller size. Furthermore, when automatic brakes are used, a braking of all cars which is as simultaneous and uniform as possible is to be achieved by means of the control device.

[0005] According to the invention, this object is achieved by means of a device having the characteristics of claim 1. Additional advantageous embodiments of a control device further developed according to the invention are described in the dependent claims.

[0006] The idea on which the invention is based is that of omitting one of the three structural components—the control sleeve, the minimum pressure limiting device and the Ü-monitor without—reducing functionality. The reason is that the control sleeve surprisingly becomes superfluous when the main air pipe is successfully connected in a meaningfully time-controlled manner to valve V 101.2. The control of this connection takes place by a valve whose position corresponds approximately to the minimal pressure limiting device F. An especially constructed control element is required which combines in itself the function of the Ü-monitor and of the A-monitor D of the known control device.

[0007] As a result, the size can be reduced by approximately 50% in comparison to the known control device while the hysteresis of the device does not exceed the normal value.

[0008] According to the invention, the control device is equipped with a control valve which, in a housing, comprises a piston rod with two pistons and a double-seat valve. Furthermore, the invention comprises the above-mentioned control element, a supply air reservoir, a control chamber and a main air pipe. One side of the first piston is connected with the main air pipe in a compressed-air carrying manner, and the other side is connected with the control chamber in a compressed-air carrying manner. On its one side, the second piston is connected in a compressed-air carrying manner with a brake cylinder pilot chamber, while an ambient pressure exists on the other side. In this case, the construction according to the invention is not limited to the wiring to a brake cylinder pilot chamber but corresponding compressed-air guiding connections directly with a brake cylinder are also conceivable. The double-seat valve is connected between a compressed-air connection to the supply air reservoir and a compressed-air connection to the brake cylinder pilot chamber. A compressed-air connection is connected parallel to the compressed-air connection from the supply air reservoir to the double-seat valve, which compressed-air connection has the above-mentioned valve which, in turn, comprises a piston rod and a piston. On one side, the piston has a compressed-air connection for a control pressure and, on the other side, a device is provided for generating a counterforce, preferably in the form of a pressure spring.

[0009] A control element is connected in the compressed-air carrying connection point between the main air pipe, the control chamber, the compressed-air connection for the control pressure, the brake cylinder pilot chamber and the environment.

[0010] The second piston of the double-seat valve is connected on its second side with the environment such that, in the case of a lower position of the piston rod with the two pistons, the brake cylinder chamber is vented by way of the ambient connection. In this case, in this lower position, the double-seat valve is advantageously closed so that the compressed-air connection of the connection pipe from the supply air reservoir to the double-seat valve—or the pipe connected parallel thereto—is separated from the brake cylinder pilot chamber. In an upper position of the piston rod with the two pistons, the double-seat valve is opened; the brake cylinder pilot chamber is separated from the environment by the second piston, so that compressed air can flow by way of the double-seat valve into the brake cylinder pilot chamber.

[0011] Advantageously, the double-seat valve is constructed as a tappet valve and is loaded in the closing direction by means of a pressure spring and in the opening direction by means of the piston rod of the control valve. In another advantageous embodiment of the invention, the above-described valve, which controls the connection between the main air pipe and the double-seat valve, is constructed as a tappet valve. Advantageously, this tappet valve can also be loaded by means of pressure spring in the closing direction and by means of the piston rod by means of the piston rod.

[0012] In an advantageous embodiment of the invention, the above-described, especially constructed control element comprises a piston rod with an axial bore, a piston, a partition, a second partition and a valve. In the piston rod, a bypass is constructed for bridging the partition. On the side of the piston facing the valve, a compressed-air connection to the brake cylinder pilot chamber is advantageously constructed and, on the side of the piston facing away from the valve, a device is arranged for generating a counterforce, advantageously in the form of a pressure spring. The compressed-air connection for the control pressure can be connected by way of the valve with the main air pipe. The piston rod is arranged such that it leads from the valve through the two partitions to the piston. On the side of the partition facing the valve, a connection is constructed for the compressed-air connection with the control pressure; on the side facing away from the valve, the compressed-air connection is connected to the control chamber. The compressed-air connection to the brake cylinder pilot chamber is separated by the second partition from the compressed-air connection to the control chamber.

[0013] Particularly advantageously, the valve is also constructed here as a tappet valve which is loaded in the closing direction by means of a pressure spring and in the opening direction by means of the piston rod.

[0014] In an advantageous embodiment of the invention, the effect of the pressure build-up and of the pressure reduction respectively in the brake cylinder pilot chamber can intensified in that a compressed-air carrying connection to another valve—for the purpose of a differentiation, in the following called a venting valve—is inserted in the connection line between the control valve and the brake cylinder pilot chamber, which venting valve opens and closes with respect to the environment. In addition, the venting valve will open up the passage to the environment when the brake cylinder pilot chamber by way of the ambient connection in the control valve is vented at a lower position of the piston rod with the two pistons. Particularly advantageously, the venting valve is therefore also constructed as a tappet valve, is loaded at least indirectly in the opening direction by the control pressure and in the closing direction particularly by means of a pressure spring. In this case, the venting valve may essentially have the same construction as the valve in the parallel pipe between the supply air reservoir and the double seat valve respectively and the main air pipe, with a piston—loaded by the control pressure and on the other side by a device for generating a counterforce—and with a piston rod which, at a correspondingly high control pressure, presses open the valve held closed particularly by the pressure spring and thus opens up the connection of the brake cylinder pilot chamber to the environment.

[0015] Particularly advantageously, an additional valve and/or a throttle screen may also be connected into compressed-air connection between the supply air reservoir and the double-seat valve. Furthermore, it is advantageous to construct the compressed-air connection from the main air pipe through the control element to the control chamber to have particular pressure losses, particularly as a result of the design of the bypass with a narrow flow cross-section. In addition, a valve and/or a throttle screen may advantageously be connected into the compressed-air connection between the control element and the control chamber. The advantages of the last-mentioned embodiments will be described in the following in the description of a braking operation by means of an embodiment of the control device according to the invention.

[0016] The invention as well as the state of the art will be explained in detail in the following by means of an embodiment and the attached drawings. Furthermore, the description of a braking operation is to clarify the method of operation of the device according to the invention.

[0017]
FIG. 1 is a view of a known control device with structural components according to Specification B-EC00.25, Picture 5 and 6;

[0018]
FIG. 2 is a view of an embodiment of the control device according to the invention;

[0019]
FIG. 3 is a view of an embodiment of the control element illustrated in FIG. 2 as a black box;

[0020]
FIG. 4 is a view of an embodiment of the control device according to the invention with an additional venting valve.

[0021]
FIG. 2 illustrates the control valve with the housing 1 in which a piston rod 6, a first piston 3, a second piston 10 and a double-seat valve 14 are arranged. One side of the piston 3 is connected by way of a compressed-air connection with the main air pipe 4; the other side is connected by way of a compressed-air connection to the control chamber 5. On its one side, the second piston 10 is connected by way of a compressed-air connection 24 with a brake cylinder pilot chamber 25. The other side of the second piston 10 is connected by way of the bore 8 with the environment. The adjacent pressure spaces of the pistons 3 and 10 are separated by a partition 9 through which the piston rod 6 is guided by means of a sliding sealing device 28.

[0022] The double-seat valve 14 is loaded by the pressure spring 27 in the closing direction and by the piston rod 6 in the opening direction. The side of the double-seat valve 14 facing away from the piston has a connection device for a compressed-air connection 11 to the supply air reservoir 7. A valve 13 and a throttle 12 are connected into this compressed-air connection 11. A compressed-air connection 2 connected parallel to the compressed-air connection 11 connects the valve 15 with the double seat valve 14. The valve 15 is constructed as a tappet valve loaded in the closing direction by the pressure spring 34 and in the opening direction by the piston rod 35. The piston 16 arranged on the side of the piston rod 35 facing away from the valve is loaded by the pressure spring 18 on its side facing the valve; the other side is connected with the compressed-air connection of the control pressure 17. In this case, the valve 15 is connected into the compressed-air connection 2 from the main air pipe 4 to the double-seat valve 14.

[0023] The control element 30 is connected into the connection point between the compressed-air pipes of the control chamber 5, the brake cylinder pilot chamber 25, the main air pipe 4, the compressed-air connection of the control pressure 17 and the environment.

[0024] As illustrated in FIG. 3, the control element 30 has a piston rod 29 with an axial bore 33 which is connected with a piston 2 on one side and with a valve 19 on the other side. The valve 19, in turn, is constructed as a tappet valve, loaded by a pressure spring 21 in the closing direction and by the piston rod 29 in the opening direction. On its side facing away from the valve, the piston 20 is loaded by a pressure spring 22 and is acted upon by ambient pressure by way of a bore.

[0025] By means of the valve 19, the partition 31, the second partition 36 and the piston 20, the control element 30 is divided into five pressure spaces. Each pressure space has a connection device for a compressed-air connection. Viewed in the axial direction from the valve 19 to the piston, these are the connections to the main air pipe 4, to the compressed-air connection device for the control pressure 17, to the control chamber 5, to the brake cylinder pilot chamber 25 and to the environment. In a suitable position of the piston rod 29, a bypass 32 in the piston rod 29 connects the pressure space ST—with the compressed-air connection device of the control pressure 17—with the pressure space A—with the connection device of the compressed-air connection to the control chamber 5—. When the valve 19 is open, the pressure space L—with the connection device for the main air pipe 4—is connected with the pressure space ST.

[0026] A throttle screen 37 is connected into the compressed-air connection between the control element 30 and the control chamber 50.

[0027]
FIG. 4 shows an embodiment according to FIG. 3 with an additionally inserted venting valve 38 for intensifying the pressure build-up and pressure reduction respectively in the brake cylinder pilot chamber 25. The venting valve 38 is connected by way of the compressed-air connection 39 with the compressed-air connection 24 between the control valve and the brake cylinder pilot chamber 25. In the open condition, the venting valve 38 connects the brake cylinder pilot chamber 25 and the ambient bore 8. In the closing direction, the venting valve 38 is loaded by the pressure spring 40 and, in the opening direction, by way of the piston 41 acted upon by control pressure and the piston rod 42. In the closing direction, the piston 41 is loaded by the pressure spring 43.

[0028] In the following, the method of operation of the control device illustrated in FIGS. 2 and 3 during a braking operation will be briefly described.

[0029] In the ready position of the control valve, the piston rod 6 with the pistons 3 and 10 is in a lower position, in which the double-seat valve 14 keeps closed the compressed-air connection of the air connections 11 and 2 and keeps the brake cylinder pilot chamber 25 vented. Since, as a result, the pressure Cv is zero or sufficiently low, the piston 20 is in a lower position because of the effect of the pressure spring 22. The valve 19 and the bypass 32 are open, and the main air pipe 4, the control chamber 5 and the compressed-air connection of the control pressure 17 are filled to the common normal operating pressure because the pressure chambers L, ST and A are connected in a compressed-air carrying manner.

[0030] Because of the effect of the control pressure 17 upon the piston 16, the valve 15 is opened up so that the main air pipe 4 is connected with the compressed-air connection 2, and the pressure from the main air pipe 4 is applied to the double-seat valve 14. In this case, the pressure in the compressed-air connection 2 is determined by the pressure in the main air pipe 4 because this pressure is higher in the ready position of the control device than the pressure which would occur only as a result of the pressure in the supply air reservoir 7 throttled by the valve 13 and the throttle 12 in the compressed-air connection 11 or 2. An unintended return flow from the compressed-air connection 2 by way of the compressed-air connection 11 into the supply air reservoir can be avoided by a suitable construction of the valve 13. The pressure in the supply air reservoir can be proportioned such that, after the throttling by way of the valve 13 and the throttle 12, a constant pressure of, for example, 3.8 bar will occur in the compressed air connection 11, as long as this pressure is not determined by a higher pressure in the maim air pipe, for example, by 5 bar in the ready position.

[0031] The method of operation of the braking can be divided into two phases. In phase 1, the pressure in the main air pipe 4 is reduced for the braking. This reduction may take place slowly, for example, by 0.1 bar per second. Since, preferably according to the invention, the bypass 32 has a narrow cross-section, the pressure in the pressure chamber A and thus in the control chamber 5 can follow this pressure reduction only in a time-delayed manner. This effect can still be reinforced by a throttle screen 37 inserted between the control element 30 and the control chamber 5. As required, a valve can also be inserted there.

[0032] The thus occurring pressure difference at the piston 3 has the result that the piston rod 6 is moved upward. The piston 10 thereby interrupts the connection of the brake cylinder pilot chamber 25 to the ambient bore 8, and the double-seat valve 14 opens up.

[0033] Now the compressed air flows from the connection 2 into the brake cylinder pilot chamber 25. Because the connection by way of the valve 15 to the main air pipe 4 is still open, compressed air flows from the main air pipe 4 into the brake cylinder pilot chamber 25. The initiation of the braking therefore causes a self-intensifying lowering of the pressure in the main air pipe 4.

[0034] As a result of the fact that, at the start of the braking, a pressure is provided for filling the brake cylinder pilot chamber 25 which is higher than the pressure normally provided by the supply air reservoir 7, in combination with the self-intensifying pressure reduction in the main air pipe 4, a fast propagation of the pneumatic brake signal from the engine to the end of train end and a uniform braking force of all cars can be achieved.

[0035] The pressure in the brake cylinder pilot chamber 25 developing in phase 1 causes a movement of the piston 20 against the force of the pressure spring 22. In phase 2, the bypass 32 therefore first slides over the sliding partition 31. Immediately afterwards, the valve 19 closes the connection of the pressures L and ST; simultaneously, the lowering of the pressure ST starts by the flowing-out of compressed air by way of the bore 22 in the piston rod 29.

[0036] After a certain time, the pressure in the chamber ST has dropped so far that the piston 16 is moved downward by means of the pressure spring 18, and the valve 15 separates the main air pipe 4 from the compressed-air connection 2. As a result, the flowing-over of compressed air from the main air pipe 4 into the brake cylinder pilot chamber 25 is concluded; the subsequent lowering of the pressure in the main air pipe 4 to the full brake application or rapid braking is not further intensified by the flowing out of air by way of the valve 15. Since the double-seat valve 14 remains open, the pressure in the compressed-air connections 2 and 11 will drop to the pressure level provided by the supply air reservoir 7, for example, to 3.8 bar. The filling rate of the brake cylinder pilot chamber 25 can therefore be adjusted by way of the valve 13 or the throttle 12 respectively.

[0037] A further lowering of the pressure in the main air pipe to a full brake application or a rapid braking, for example, to 3.5 bar or to 0 bar, leads to an increase of the pressure difference above the piston 3. As a result of the displacement of the piston rod 6, the double-seat valve 14 is opened up correspondingly far, and the brake cylinder pilot chamber 25 is filled further.

[0038] By means of the present invention, it therefore becomes possible for the first time to provide a control device for compressed-air brakes which requires low constructional expenditures and has a small size. When used for automatic brakes, the construction of the described control device according to the invention results in a high penetration speed because of the reaction of the pressure build-up in the brake cylinder or in the brake cylinder pilot chamber on the pressure in the main air pipe and thus in a simultaneous braking effect in all cars. By means of a pressure increase in the brake cylinders which is fast at first and then slower, a uniform braking force is achieved for all cars.

List of Reference Numbers

[0039]

1
Control valve housing

[0040]

2
compressed-air connection

[0041]

3
piston

[0042]

4
main air pipe

[0043]

5
control chamber

[0044]

6
piston rod

[0045]

7
supply air reservoir

[0046]

8
ambient bore

[0047]

9
partition

[0048]

10
second piston

[0049]

11
compressed-air connection

[0050]

12
throttle

[0051]

13
valve

[0052]

14
double-seat valve

[0053]

15
valve

[0054]

16
piston

[0055]

17
control pressure

[0056]

18
pressure spring

[0057]

19
valve

[0058]

20
piston

[0059]

21
pressure spring

[0060]

22
pressure spring

[0061]

23
compressed-air connection to the brake cylinder pilot chamber

[0062]

24
compressed-air connection

[0063]

25
brake cylinder pilot chamber

[0064]

27
pressure spring

[0065]

28
sealing device

[0066]

29
piston rod

[0067]

30
control element

[0068]

31
partition

[0069]

32
bypass

[0070]

33
axial bore

[0071]

34
pressure spring

[0072]

35
piston rod

[0073]

36
second partition

[0074]

37
throttle screen

[0075]

38
venting valve

[0076]

39
compressed-air connection

[0077]

40
pressure spring

[0078]

41
piston

[0079]

42
piston rod

[0080]

43
pressure spring

Control device for compressed-air brakes

Information

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Date Filed

Date Published

Inventors

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CPC

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Abstract

Description

Claims

Priority Claims (1)