Bi-Stable Valve

Abstract

A valve arrangement for use in a parking brake system of a commercial vehicle or trailer, includes a differential piston having a first section and a second section, wherein the second section has a smaller diameter compared to the first section, and wherein there is a fluidic connection between the first section and the second section. The arrangement includes a housing with a bore, in which the differential piston is adapted to move. The bore has at least two sections, wherein the first section corresponds to the diameter of the first section of the differential piston, and the second section corresponds to the diameter of the second section of the differential piston, and wherein a step is formed between the first section and second section of the bore. A first passage and a second passage are arranged and axially spaced in the bore, and a third passage is arranged in or next to the second section of the bore. When the differential piston is in a first end position, the second section of the differential piston rests against the step, and a connection of the first passage and the second passage within the bore is provided. When the differential piston is in a second end position, a connection of the first passage and the second passage within the bore is blocked.

Claims

1. A valve arrangement, comprising: a differential piston comprising a first section and a second section, wherein the second section has a smaller diameter compared to the first section, and wherein there is a fluidic connection between the first section and the second section; a housing with a bore, in which bore the differential piston is adapted to move, wherein the bore has at least two sections, wherein a first bore section corresponds to the diameter of the first section of the differential piston, and a second bore section corresponds to the diameter of the second section of the differential piston, wherein a step is formed between the first bore section and second bore section of the bore, wherein a first passage and a second passage are arranged and axially spaced in the bore, and a third passage is arranged in or next to the second bore section of the bore, wherein, when the differential piston is in a first end position, the second section of the differential piston rests against the step, and a connection of the first passage and the second passage within the bore is provided, and wherein, when the differential piston is in a second end position, a connection of the first passage and the second passage within the bore is blocked.

2. The valve arrangement according to claim 1, wherein a fourth passage is arranged in the first bore section of the bore, which allows an insertion of pressurized fluid into the first bore section of the bore.

3. The valve arrangement according to claim 1, wherein the differential piston further comprises a third section, wherein, when the differential piston is in a first end position, the third section of the differential piston provides a connection of the first passage and the second passage within the bore, and wherein, when the differential piston is in a second end position, the third section of the differential piston blocks a connection of the first passage and the second passage within the bore.

4. The valve arrangement according to claim 3, wherein the third section of the differential piston has a smaller diameter compared to at least one of: the first section, the second section, the first bore section, or the second bore section.

5. The valve arrangement according to claim 2, wherein the fourth passage is connected to a fourth port via a first check valve, which only allows a flow from the fourth port to the fourth passage, wherein a reset button is optionally connected to the fourth port.

6. The valve arrangement according to claim 5, wherein the first passage and the second passage are connected outside of the bore by a second check valve, which only allows a flow of fluid from the second passage to the first passage.

7. The valve arrangement according to claim 5, wherein the bore accommodating the differential piston and the first check valve are accommodated in a common housing.

8. The valve arrangement according to claim 6, wherein the bore accommodating the differential piston, the first check valve, and the second check valve, are accommodated in a common housing.

9. The valve arrangement according to claim 1, wherein the fluidic connection between the first section and the second section of the differential piston comprises a channel and/or a hollow pin through the differential piston.

10. The valve arrangement according to claim 9, wherein the channel and/or the hollow pin in the differential piston is/are the only fluidic connection between the first bore section and the second bore section of the bore.

11. The valve arrangement according to claim 1, further comprising: a lock pre-tensioned by a spring provided at the bore, wherein the lock is adapted to be releasably pressed against the differential piston.

12. The valve arrangement according to claim 11, wherein the pre-tensioning of the spring is adjustable by a screw.

13. The valve arrangement according to claim 1, wherein the third passage is connected to a third port, through which fluid pulses of different duration are insertable.

14. The valve arrangement according to claim 1, wherein the valve arrangement is integrally formed with an electronic brake control module.

15. The valve arrangement according to claim 1, wherein the first bore section of the bore and the third passage are connected via an internal connection, wherein a third check valve is provided within the internal connection, only allowing air flow from the first bore section of the bore to the third passage, wherein the internal connection optionally leads through an internal pocket.

16. The valve arrangement according to claim 1, wherein a first port is connected to the first passage, and a second port is connected to the second passage.

17. The valve arrangement according to claim 16, wherein the first port is connected to a park and shunt valve, the second port is connected to an electronic brake module, and the third port is connected to a control port.

18. The valve arrangement according to claim 1, further comprising: a double check valve, wherein one side of the double check valve is connected to the third port, and another side of the double check valve is connected to the second passage, whereby the second port is connected with either the second passage or the third port, and the second port is connected with the second passage when the pressure in the second passage is higher compared to the third port, and the second port is connected with the third port when the pressure in the third port is higher compared to the second passage.

19. The valve arrangement according to claim 18, wherein the double check valve is provided in the housing of the differential piston.

20. The valve arrangement according to claim 18, wherein the first port is connected to a park and shunt valve, the second port is connected to an electronic brake module, and the third port is connected to a control port.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 shows a partial sectional view of a valve arrangement according to a first embodiment of the present invention.

[0058] FIG. 2 shows an isometric view from the side of the valve arrangement according to the first embodiment of the present invention.

[0059] FIG. 3 shows another partial sectional view of the valve arrangement according to the first embodiment of the present invention.

[0060] FIG. 4 shows a sectional view of a second embodiment of a valve arrangement according to the present invention.

[0061] FIG. 5 shows a detailed view of the double-check valve as used in the second embodiment of the present invention.

[0062] FIG. 6 shows a partial sectional view of a valve arrangement according to a second embodiment of the present application.

[0063] FIG. 7 shows an isometric side view of the valve arrangement according to a second embodiment of the present invention.

[0064] FIG. 8 shows a pneumatic circuit diagram of a valve arrangement according to a second embodiment of the present invention, used as a parking brake valve.

[0065] FIG. 9 shows an electronic brake module and a valve arrangement according to the present invention being integrally formed.

DETAILED DESCRIPTION OF THE DRAWINGS

[0066] In FIG. 1, a partial sectional view of a valve arrangement 1 according to a first embodiment of the present application is shown. A housing 4 contains a bore 5, which has a first section 5a and a second section 5b. A step 5c is provided between the first section 5a and the second section 5b, as the first section 5a has a larger diameter compared to the second section 5b. Within the bore 5, a differential piston 2 (not explicitly labelled in FIG. 1) is arranged, which has a first section 2a, a second section 2b, a third section 2c and a fourth section 2d. On the right side, there is the first section 2a with the largest diameter, then a step follows, and a fourth section 2d follows, and then a third section 2c will follow, with an even decreased diameter compared to the fourth section 2d, and then a second section 2b follows. The second section 2b has a smaller diameter compared to the first section 2a, but the same diameter as the fourth section 2d.

[0067] The axial length of the first section 2a of the differential piston 2 is smaller compared to the first section 5a of the bore 5—so that the differential piston 2 can move within the bore 5.

[0068] Within the housing 4, a first port 12, a second port 13 and a third port 14 are visible. The first port 12 is connected to a first passage 6, the second port 13 is connected to a second passage 7, and the third port 14 is connected to a third passage 8.

[0069] The first passage 6 and the second passage 7 are connected with the second section 5b of the bore 5. In FIG. 1, the second section 2b of the differential piston blocks the connection of the first passage 6 and the second passage 7 within the second section 5b of the bore 5. The differential piston 2 is in the second end position.

[0070] In the first end position (not shown in FIG. 1), the third section 2c of the differential piston 2 (with a smaller diameter compared to the second section 2b) would be positioned in the region where the first channel 6 and the second channel 7 are connected with the second section 5b of the bore 5—hence allowing a connection between the first passage 6 and the second passage 7 within the bore 5.

[0071] Furthermore, there is a second check valve 11 arranged between the first passage 6 and the second passage 7, however, it is only possible to open said second check valve 11 if the pressure in the second passage 7 is higher compared to the first passage 6.

[0072] Furthermore, an air pocket 20 is visible within the housing 4.

[0073] Furthermore, there is a first check valve 7, which is connected to the fourth passage 9. The fourth passage 9 is connected to the first section 5a, i.e. the section with the larger diameter of the bore 5.

[0074] On the other hand, the third passage 8 is connected to the second section 5b, which is the section with the smaller diameter of the bore 5—more precisely with its left end.

[0075] In the first check valve 10, air can only flow towards the fourth passage 9 and hence the first section 5a of the bore 5, but not in the other direction. The first check valve 10 is furthermore connected with the fourth port 15 (not shown in this embodiment).

[0076] The differential piston 2 is hollow—forming a channel 3a, which comprises a highly throttled hollow pin 3b. Hence, if a short pulse of air is inserted through the third passage 8, the differential piston 2 will move to the right side (second end position)—as depicted in FIG. 1. However, if a longer air pulse is inserted through the third passage 8, the pressure can propagate through the hollow pin 3b and reach the first section 5a of the bore 5—as the first section 2a of the differential piston 2 has a higher diameter compared to the second section 2b, a higher area is present onto which the pressure can act—and hence the piston would move to the left side (first end position)—not shown in FIG. 1. However, pressurized air can also be inserted to the first section 5a of the bore 5 directly via the fourth passage 9—hence, the piston would move to the left side (first end position).

[0077] In FIG. 2, an isometric side-view of a valve arrangement 1 according to a first embodiment of the present application is shown. Again, the first port 12 and the second port 13 and the third port 14 are visible. Also, the bore 5 is partially visible. Herein, the function of the first check valve 10 is further explained: Air can flow from a fourth port 15 through the check valve 12, and then can enter the fourth passage 9, but no air can flow in the different direction. Hence, pressurized air can reach the first section 5a of the bore 5.

[0078] In FIG. 3, another partial sectional view of a valve arrangement 1 according to a first embodiment of the present application is shown. Herein, it is visible that there is an internal connection 23 between the first section 5a of the bore 5 and the third passage 8, which leads through an internal pocket 20, which is a cavity with a defined volume. Furthermore, there is a third check valve 21 which only allows a flow of air from the first section 5a of the bore 5 to the third passage 8 (i.e. which only opens if the in the pressure first section 5a of the bore 5 is higher compared to the third passage 8).

[0079] FIG. 4 shows a sectional view of a valve arrangement 1 according to a second embodiment of the present application. The position of the differential piston 2 with the first section 2a, the second section 2b, the third section 2c and the fourth section 2d is identical to FIG. 1, as well as the arrangement of the bore 5 in the first section 5a and the second section 5b. Also, the first passage 6 and the second passage 7 and the fourth passage 9, the first check valve 10 and the second check valve 11 and the channel 3a and the hollow pin 3b are identical to the first embodiment. The difference is that the top part of the housing 4, a double-check valve 19 is provided, acting as a pressure selector valve

[0080] FIG. 5 shows the double-check valve 19 more in detail. In one position (as shown in FIG. 5), the double-check valve 19 connects the third passage 8 with the second port 13. In the other position (not as shown in FIG. 5), the double-check valve 19 connects the second passage 7 with the second port 13. Depending on whether the pressure and the second passage 7 or the third passage 8 is larger, a connection is made to the second port 13.

[0081] FIG. 6 shows a partial sectional view of a valve arrangement 1 according to a second embodiment of the present application. Herein, the structure of the first port 12 is visible more in detail, as well as the structure of the second port 13. The first port 12 is connected to the first passage 6. Also it is shown that a locking means 16, which is a bore, is provided in the bore 5, and the locking means 16 is locked by a spring 17, which is adjusted by a screw 18. Herein, the position of the differential piston 2 can be locked, i.e. there is a higher force necessary in order to move the differential piston 2. All other parts are the same as in FIG. 5.

[0082] FIG. 7 again shows an isometric side-view and a valve arrangement 1 according to a second embodiment of the present application. Again, it is visible that the fourth port 15 is present, which is connected to a first check valve 10. If air enters the first check valve 10 from the first port 15, the first check valve 10 opens and air can get via the fourth passage 9 into the first section 5a of the bore. Hence, the differential piston 2 can be moved independently of whether there is a pressure pulse in the third passage 8 (not shown in FIG. 7).

[0083] FIG. 8 shows a pneumatic circuit diagram of a valve arrangement 1 according to a second embodiment of the present invention, used as a parking brake valve. Herein the driving position is shown, which corresponds to the first end position. Herein, a connection of the first port 12 and the second port 13 is realized via the differential piston 2—a flow of air is possible in both directions. If the differential piston 2 would be in the second end position (not shown in FIG. 8), only an air flow into the direction from the second port 13 to the first port 12 would be possible. The third port 14 is connected to a control port, through which different air pulses can be inserted. Because of the hollow pin 3b (throttle), the duration of the air pulses decides about the position of the differential piston 2.

[0084] Herein, the first port 12 is connected to a park and shunt valve, and the second port 13

[0085] is connected to an electric brake module EBS. The third port 14 is connected to a control port, and the fourth port 15 is connected to a reset button 22. The first check valve 10 allows air pulses from the reset button 22 to the differential piston 2, which would move it to the first end position, which is the driving position. The double-check valve 19 decides which port (third port 14 or first port 12) is connected to the second port 13, leading to the EBS. If the pressure in the third port 14 is higher compared to the first port 12, the third port 14 and the second port 13 are connected—if the pressure in the first port 12 is higher compared to the third port 14, the first port 12 and the second port 13 are connected. If the pressure at the first port 12 is decreasing, the pressure at the second port 13 follows, as the second check valve 11 opens. In this case, the parking brake (emergency brake) of a trailer of a utility vehicle can be actuated, but depending on a software logic, it could be overridden. Such override is possible in case of an existing electric connection. If the pressure at the first port 12 is smaller than the pressure at the third port 14, the double-check valve 19 separates the first port 12 and the second port 13. At the same time, the third port 14 is connected with the second port 13 therefore the EBS system is pressurized by system pressure from e.g. a reservoir of the trailer. In this case, a short pressurized air pulse is used for switching to the safe park position, a longer signal is used for switching to the drive position, and a permanent signal is used for emergency override

[0086] FIG. 9 shows an electronic brake module EBS and a valve arrangement 1 according to the present invention being integrally formed, leading to a compact part.

[0087] The present invention is not limited to the above mentioned embodiments. The differential piston 2 can have more sections, as well as the bore 5.

[0088] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.