Compressed air brake system for a vehicle and method for operating a compressed air brake system

Abstract

A compressed air brake system (20) for a vehicle and a method for operating the compressed air brake system are provided. The compressed air brake system has a pilot control switching device (21) of a diaphragm valve (1), the pilot control switching device having: a first valve device (22) that can be connected to a first compressed air source (23) at a first interface and to a pilot control inlet (10) of the diaphragm valve (1) at a second interface. The first valve device is configured to connect and disconnect the first interface of the first valve device with the second interface of the first valve device, and the pilot control switching device is configured to provide a predetermined pilot control pressure at the pilot control inlet (10). In addition, the pilot control switching device also has a second valve device (24) that is connected to a second compressed air source (23') at the first interface of the second valve device and to the pilot control inlet at the second interface of the second valve device.

Description

Technical Field

[0001] The invention relates to a compressed air brake system for a vehicle and a method for operating a compressed air brake system, in particular a compressed air brake system having a diaphragm valve. Background Art

[0002] In the prior art, it is well known to use a diaphragm valve as an ABS valve or anti-skid valve in a vehicle.

[0003] However, due to the system-induced inertia of the compressed air brake system, it is difficult to control the diaphragm valve to achieve more precise switching times and more accurately determine the outlet pressure of the diaphragm valve, so that it is not easy to achieve the expected, fast and precise switching performance of the diaphragm valve. Summary of the Invention

[0004] The object of the present invention is therefore to improve a compressed air brake system for a vehicle such that more precise switching times of a diaphragm valve of the compressed air brake system can be achieved and the outlet pressure of the diaphragm valve of the compressed air brake system can be determined more precisely.

[0005] This object is achieved by the compressed air brake system according to the invention and the method according to the invention.

[0006] According to one aspect of the present invention, a compressed air brake system for a vehicle includes a diaphragm valve and a pilot control switching device for the diaphragm valve, wherein the pilot control switching device includes a first valve device that can be connected to a first compressed air source at a first port and to a pilot control inlet of the diaphragm valve at a second port, wherein the first valve device is configured to connect and disconnect its first port from its second port, and the pilot control switching device is configured to provide a predetermined pilot pressure at the pilot control inlet, and the pilot control switching device includes a second valve device that is connected to a second compressed air source at the first port and to the pilot control inlet at the second port. Furthermore, the pilot control switching device is configured to apply a pilot pressure to the pilot control inlet of the diaphragm valve by opening the first valve device and opening the second valve device, thereby closing the diaphragm valve.

[0007] In such compressed air brake systems, this pilot control switching device allows for greater control variability with respect to pressure changes. By using a second valve device, for example, the air flow to the pilot control inlet of the diaphragm valve can be increased to shorten the diaphragm valve response time without having to use an overly large valve with a high air flow rate.

[0008] According to an advantageous development of the compressed air brake system, the first valve device comprises a 3 / 2-way valve.

[0009] The 3 / 2-way valve of the first valve arrangement allows a predefined pressure to be applied to the pilot control inlet of the diaphragm valve and the pilot control pressure to be reduced again by venting via the 3 / 2-way valve in order to actuate the diaphragm valve as required.

[0010] In a further advantageous development of the compressed air brake system, the first valve device comprises a 2 / 2-way valve.

[0011] Such a valve can be used, for example, if there is a possibility for air to escape through an opening in the diaphragm of the diaphragm valve. Thus, when the 2 / 2-way valve is closed, the pilot pressure can be reduced. In this case, the 2 / 2-way valve offers an economical and simple way to operate the diaphragm valve.

[0012] In another advantageous embodiment of the compressed air brake system, the second valve device comprises a 2 / 2-way valve.

[0013] The second valve arrangement with a 2 / 2-way valve offers an economical possibility of increasing the air volume flow to the pilot control inlet of the diaphragm valve in order to shorten the response time when closing the diaphragm valve.

[0014] According to another advantageous embodiment of the compressed air brake system, the second valve device comprises a 3 / 2-way valve.

[0015] By using a 3 / 2-way valve with the second valve arrangement, the pilot pressure can be reduced more quickly than if only a 3 / 2-way valve were used with the first valve arrangement or if the air were to escape only through the opening in the diaphragm. This shortens the response time of the diaphragm valve when opening, without having to use an overly large valve with a high air flow rate.

[0016] According to a further advantageous embodiment of the compressed air brake system, it is designed to provide the first valve device and the second valve device with the same input pressure via the first and second compressed air sources.

[0017] By providing the same input pressure, there is no need for a different pressure regulator for the pilot control switching device, however the air flow to the pilot control inlet can be increased, thus shortening the diaphragm valve response time.

[0018] In a further advantageous embodiment of the compressed air brake system, it is designed to provide different input pressures to the first and second valve devices via a first and a second compressed air source.

[0019] By providing different pressures, different performances of the diaphragm valve can be achieved depending on the current operating state.

[0020] In an advantageous embodiment of the compressed air brake system, the input pressure of the second valve device is greater than the input pressure of the first valve device.

[0021] This behavior allows, for example, the pilot control inlet to be charged with only a low pressure via the first valve device during so-called normal operation, whereas under certain conditions requiring a short diaphragm valve response time, a higher pilot control pressure is provided via the second valve device.

[0022] In another advantageous embodiment of the compressed air brake system, the inlet of the diaphragm valve is connected to the brake cylinder via a brake line, so that the diaphragm valve is designed for venting the brake cylinder via the brake line, and the first port of the first valve device is connected to the brake line.

[0023] This design makes it possible to increase the pressure in the brake line and thus in the brake cylinder in addition without using any additional components in order to produce a particularly precise braking effect.

[0024] According to another aspect of the present invention, a method for operating a compressed air brake device includes the following steps: applying a pilot pressure at a pilot inlet of a diaphragm valve by opening a first valve device and opening a second valve device, thereby closing the diaphragm valve, and reducing the pilot pressure by closing the first valve device and closing the second valve device, thereby opening the diaphragm valve.

[0025] These steps can be used to increase the air flow to the pre-control inlet of the diaphragm valve to shorten the diaphragm valve response time without having to use an oversized valve with a high air flow rate.

[0026] According to an advantageous embodiment of the method, a higher pilot pressure is provided by opening the second valve device than when the first valve device is opened.

[0027] By providing a higher pilot pressure, the diaphragm valve can be closed more quickly because, with the same diaphragm area, a greater force is present and the necessary switching pressure is reached more quickly.

[0028] In a further advantageous embodiment of the method, the second valve device is opened only when predetermined conditions exist.

[0029] In normal operation, the pilot control inlet is only loaded with a low pressure via the first valve arrangement. However, under certain conditions requiring a shorter diaphragm valve response time, a higher pilot control pressure is provided via the second valve arrangement, thereby enabling faster valve closing.

[0030] In a further advantageous embodiment of the method, the second valve device is closed upstream of the first valve device.

[0031] This property allows the diaphragm valve to be closed quickly, while the force pressing the diaphragm against the stop surface can be reduced by closing the valve arrangement providing a higher pilot pressure, thereby extending the service life of the diaphragm.

[0032] In a further advantageous embodiment of the method, the higher input pressure is provided both in the pilot control inlet and in the brake line and at the brake inlet of the diaphragm valve.

[0033] By providing this, the pressure in the brake line can be increased even without the use of additional components, in order to achieve a particularly precise pressure regulation and thus a particularly precise braking effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be described below based on embodiments and with reference to the accompanying drawings. The accompanying drawings particularly show:

[0035] Figure 1 is a cross section of the upper part of a diaphragm valve;

[0036] Figure 2 A detail of a first embodiment of a compressed air brake device, including a schematic diagram of a diaphragm valve and a schematic diagram of a pilot control switching device for the diaphragm valve; and

[0037] Figure 3 It is a detail of a second embodiment of a compressed air brake system, including a schematic diagram of a diaphragm valve and a schematic diagram of a pilot control switching device for the diaphragm valve, the pilot control switching device being connected to a brake line of a brake cylinder. DETAILED DESCRIPTION

[0038] Figure 1 The upper part of a diaphragm valve 1 is shown in cross section.

[0039] The diaphragm valve 1 has a valve housing 2 which is connected to a housing cover 4 in the region of a control pressure chamber 3. An elastomeric diaphragm 5 is arranged between the valve housing 2 and the housing cover 4 for actuating a closure element 6 driven by the elastomeric diaphragm.

[0040] An annular support contour 8 is provided on the side of the lower diaphragm surface 7 of the elastomeric diaphragm 5 , which is formed by a support ring 9 which engages in a form-fitting manner in the valve housing 2 .

[0041] Furthermore, a pilot control inlet 10 of the diaphragm valve 1 is provided in the housing cover 4 for supplying control pressure to the diaphragm valve 1. In alternative embodiments, the diaphragm valve 1 can also have a different design, in which functional elements such as the elastomer diaphragm 5 and the closure are present and function accordingly.

[0042] Figure 2 A detail of a first embodiment of a compressed air brake system 20 is shown, including a schematic diagram of a diaphragm valve 1 and a schematic diagram of a pilot control switching device 21 of the diaphragm valve 1 .

[0043] The pilot control switching device 21 has a first valve device 22 and a second valve device 24 . The pilot control switching device 21 is designed to provide a previously determined pilot control pressure at the pilot control inlet 10 .

[0044] The first valve device 22 is connected to a first compressed air source 23 at a first port and to the pilot control inlet 10 of the diaphragm valve 1 at a second port, wherein the first valve device 22 is configured to connect and disconnect the first port from the second port. The first valve device 22 comprises a 3 / 2-way valve. In an alternative embodiment, the first valve device 22 comprises a 2 / 2-way valve or other suitable valve.

[0045] The second valve device 24 is connected to the second compressed air source 23' at a first port, and is connected to the pilot control inlet 10 of the diaphragm valve 1 and the second port of the first valve device 22 at a second port. The second valve device 24 comprises a 2 / 2-way valve. In an alternative embodiment, the second valve device 24 comprises a 2 / 2-way valve or other suitable valve.

[0046] The compressed air brake system 20 is configured to provide an input pressure to the second valve device 24 via the second compressed air source 23' that is greater than the input pressure of the first valve device 22 provided by the first compressed air source 23. In this embodiment, the pressure provided by the first compressed air source 23 is 4 bar, while the pressure provided by the second compressed air source 23' is 7 bar. In alternative embodiments, the pressures may also take other values; the pressure provided by the first compressed air source 23 may be higher than the pressure provided by the second compressed air source 23', or the pressures provided by the first compressed air source 23 and the pressures provided by the second compressed air source 23' may be the same.

[0047] Figure 3 A detail of a second embodiment of a compressed air brake system 20 is shown, comprising a schematic diagram of a diaphragm valve 1 and a pilot control switching device 21 of the diaphragm valve 1 , which is connected to a brake line 25 of a brake cylinder 26 .

[0048] The second embodiment differs from the first embodiment in that the first connection of the first valve device 22 is connected to a brake line 25. As indicated by the arrow, as long as the diaphragm valve 1 is open, the brake cylinder 26 is exhausted via the brake line 25. When a corresponding pressure is present, the brake line 25 can function as a first pressure source 23.

[0049] In addition, when a higher pressure is provided by the second pressure source 23 ′, the pressure in the brake line 25 can also be increased by the first valve device 22 and the second valve device 24 , so that very precise pressure regulation in the brake line 25 is possible.

[0050] During operation, when there is no pilot pressure in the control pressure chamber 3, the elastomeric diaphragm 5 is pressed upward by the closure element 6, thereby opening the diaphragm valve 1. The pilot pressure entering the control pressure chamber 3 via the pilot inlet 10 presses the elastomeric diaphragm 5 downward. Simultaneously, the diaphragm valve 1 is closed by means of the closure element 6.

[0051] The diaphragm valve 1 can be actuated solely by the first valve device 22. However, according to the present invention, the diaphragm valve 1 is actuated by applying a pilot pressure to the pilot inlet 10 of the diaphragm valve 1 by opening the first valve device 22 and by opening the second valve device 24, thereby closing the diaphragm valve 1. If necessary, the pilot pressure is reduced by closing the first valve device 22 and closing the second valve device 24, thereby opening the diaphragm valve 1. In the case of a 3 / 2-way valve, the compressed air supply to the diaphragm valve 1 is interrupted by closing the valve, and the line to the pilot inlet 10 is vented via the valve.

[0052] By opening the second valve device 24 , a higher pilot pressure is provided at the pilot inlet 10 than when the first valve device 22 is open. Alternatively, the same pilot pressure can be provided at the pilot inlet 10 .

[0053] The second valve device 24, which provides a higher pilot pressure at the pilot inlet 10, is opened only when predetermined conditions are met. For example, the second valve device 24 can be briefly opened when the first valve device 22 is opened to achieve a desired short response time for closing the diaphragm valve 1, as may be desirable in anti-slip control. If a short response time is not required, the simultaneous opening of the second valve device 24 can be omitted. Alternatively, the second valve device 24 can always be opened simultaneously with the first valve device 22.

[0054] The second valve device 24 is closed before the first valve device 22. This prevents the diaphragm 5 from being pressed against the annular support contour 8 with great force due to the high pilot pressure applied by the second valve device 24, thereby preventing high wear of the diaphragm 5.

[0055] If the first connection of first valve device 22 is connected to brake line 25, the higher pressure provided by second valve device 24 can also be provided in brake line 25. Due to this higher pressure present both in brake line 25 and in pilot control inlet 10, the pressure in brake line 25 and thus the braking effect can be adjusted very precisely.

[0056] Although the present invention has been described with reference to certain features and embodiments, it is apparent that various modifications and combinations are possible without departing from the inventive concept and scope of the present invention. Therefore, the specification and drawings should only be regarded as an explanation of the present invention as defined by the appended claims, and should cover all modifications, alterations, combinations or equivalent features that fall within the scope of application of the present invention.

[0057] Reference Signs List

[0058] 1 Diaphragm valve

[0059] 2 Valve housing

[0060] 3 Control pressure chamber

[0061] 4 Shell cover

[0062] 5 Elastomer diaphragm

[0063] 6 Closure

[0064] 7 Lower diaphragm surface

[0065] 8 Annular support profile

[0066] 9 Support ring

[0067] 10 Pre-control entrance

[0068] 20 Compressed air brake equipment

[0069] 21 Pre-control switchgear

[0070] 22 First valve device

[0071] 23, 23' Compressed air source

[0072] 24 Second valve device

[0073] 25 brake line

[0074] 26 brake cylinder

[0075] 27 Entrance

Claims

1. A compressed air brake system (20) for a vehicle, comprising a diaphragm valve (1) and a pilot control switching device (21) for the diaphragm valve (1), the pilot control switching device (21) having: a first valve device (22) which can be connected to a first compressed air source (23) at a first connection of the first valve device (22) and can be connected to a pilot control inlet (10) of the diaphragm valve (1) at a second connection of the first valve device (22), The first valve device (22) is configured to connect and disconnect a first interface of the first valve device (22) with a second interface of the first valve device (22), and The pilot control switching device (21) is designed to provide a predetermined pilot control pressure at the pilot control inlet (10). The pilot control switching device (21) further comprises a second valve device (24), which is connected to a second compressed air source (23') at a first connection of the second valve device (24) and to a second connection of the first valve device (22) and to a pilot control inlet (10) at a second connection of the second valve device (24), and The pilot control switching device (21) is designed to close the diaphragm valve (1) by applying a pilot control pressure to the pilot control inlet (10) of the diaphragm valve (1) by opening a first valve device (22) and by opening a second valve device (24).

2. The compressed air brake system (20) according to claim 1, wherein the first valve device (22) comprises a 3 / 2-way valve.

3. The compressed air brake system (20) according to claim 1, wherein the first valve device (22) comprises a 2 / 2-way valve. 4 . The compressed air brake system ( 20 ) according to claim 1 , wherein the second valve device ( 24 ) comprises a 2 / 2-way valve. 5 . The compressed air brake system ( 20 ) according to claim 1 , wherein the second valve device ( 24 ) comprises a 3 / 2-way valve.

6. The compressed air brake device (20) according to claim 1 or 2, wherein the compressed air brake device (20) is designed to provide the first valve device (22) and the second valve device (24) with the same input pressure via the first and second compressed air sources (23, 23').

7. The compressed air brake device (20) according to claim 1 or 2, wherein the compressed air brake device (20) is designed to provide different input pressures to the first valve device (22) and the second valve device (24) via a first and a second compressed air source (23, 23').

8. The compressed air brake system (20) according to claim 7, wherein an input pressure of the second valve device (24) is greater than an input pressure of the first valve device (22).

9. The compressed air brake device (20) according to claim 8, wherein The inlet (27) of the diaphragm valve (1) is connected to the brake cylinder (26) via the brake line (25), so that the diaphragm valve (1) is configured to exhaust the brake cylinder (26) through the brake line (25), and The first interface of the first valve device (22) is connected to the brake line (25).

10. A method for operating a compressed air brake system (20) according to any one of claims 1 to 9, comprising the following steps: closing the diaphragm valve (1) by opening the first valve device (22) and applying a pilot pressure at the pilot inlet (10) of the diaphragm valve (1) by opening the second valve device (24); and The diaphragm valve (1) is opened by closing the first valve device (22) and reducing the pilot pressure by closing the second valve device (24).

11. The method according to claim 10, wherein a higher pilot pressure is provided by opening the second valve device (24) than when the first valve device (22) is opened.

12. The method according to claim 10 or 11, wherein the second valve device (24) is opened only when predetermined conditions exist.

13. Method according to claim 11, wherein the second valve device (24) is closed before the first valve device (22).

14. A method according to claim 11, using a compressed air supply device according to claim 9, wherein the larger input pressure of the input pressures provided by the first and second compressed air sources (23, 23') is provided both in the pilot control inlet (10), in the brake line (25) and at the brake inlet (27) of the diaphragm valve (1).

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