An empty and loaded car valve for rail transit vehicles

Abstract

The utility model discloses a kind of empty heavy car valves for rail transit vehicles, belong to rail transit vehicle braking control technical field;The utility model is provided with the valve body with at least two cavities, first piston device and second piston device are respectively installed in the cavity, at least two air spring pressure air ports T are opened in the valve body side, brake air cylinder interface R and output emergency brake pressure interface Ev are opened in the other side;Among them, the valve body is located at the top of the cavity and is provided with spring adjusting device, is equipped with the balancing mechanism for adjusting the first piston device and the second piston device at the bottom of the cavity, the adjusting bolt of the balancing mechanism is horizontally arranged, the adjusting end of the adjusting bolt is coplanar with the brake air cylinder interface R and the output emergency brake pressure interface Ev.The utility model realizes the need of a variety of installation mode, with high integration, beneficial effect of being conducive to improving train braking safety.

Description

Technical Field

[0001] This utility model relates to the field of braking control technology for rail transit vehicles, and in particular to an empty / loaded vehicle valve for rail transit vehicles. Background Technology

[0002] Rail transit vehicles typically require braking force to be automatically adjusted according to changes in vehicle load. They use air springs to bear the load. When the vehicle load changes, the air spring pressure will automatically change. Therefore, the vehicle braking system uses the air spring pressure as the load signal source and uses the empty / loaded vehicle valve to generate a braking control pressure corresponding to the air spring in a certain proportion, i.e., pre-control pressure, so as to adjust the braking force.

[0003] Currently, traditional empty / loaded vehicle control valves use three adjusting bolts for pressure regulation. These three bolts occupy three contact surfaces, including the upper and lower surfaces. Because the balance bar of the empty / loaded vehicle control valve must be placed horizontally, this design only allows for a single installation direction. Therefore, in most cases, to ensure the balance bar of the empty / loaded vehicle control valve is placed horizontally, and because the lower contact surface cannot be fitted with adjusting bolts due to its connection to external components,

[0004] Therefore, in response to the above problems, those skilled in the art urgently need to develop a new empty and loaded vehicle valve to meet the needs of various installation methods. Utility Model Content

[0005] The purpose of this invention is to overcome the defects of the existing technology and provide a highly integrated empty and loaded car valve for rail transit vehicles, which solves the problem of the single installation method of the empty and loaded car valve in the existing technology.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] This utility model discloses an empty / loaded car valve for rail transit vehicles, comprising:

[0008] A valve body having at least two cavities, and a first piston device and a second piston device respectively installed in the cavities:

[0009] The valve body has at least two air spring pressure ports T on one side and a brake cylinder interface R and an emergency brake pressure output interface Ev on the other side.

[0010] The valve body is provided with a spring adjustment device at the top of the cavity and a balance mechanism for adjusting the first piston device and the second piston device is installed at the bottom of the cavity. The adjustment bolt of the balance mechanism is horizontally set, and the adjustment end of the adjustment bolt is coplanar with the brake cylinder interface R and the output emergency brake pressure interface Ev.

[0011] Furthermore, the adjusting bolt extends below the first piston assembly via an extension rod and forms a balance fulcrum via an adjusting roller.

[0012] Furthermore, the balancing mechanism includes an adjustable balance bar and a fixed balance bar;

[0013] The adjustable balance bar is horizontally positioned below the first piston device, with its lower surface in contact with the adjusting roller, one end of its upper surface in contact with the first piston device, and the other end in contact with the fixed balance bar via a connecting rod.

[0014] The fixed balance bar is rotatably connected to the valve body, and the end of the fixed balance bar away from the connecting rod is inserted between the second piston device and the spring adjusting device.

[0015] Furthermore, an adjusting piston is provided between the first piston device and the spring adjusting device, and a bushing is installed on the side wall of the cavity of the valve body, the bushing being in sealing contact with the adjusting piston.

[0016] Furthermore, the first piston device is a double-diaphragm piston, which includes a first main rod, the bottom end of which contacts the balancing mechanism.

[0017] Furthermore, a first limiting body is provided below the first piston device on the valve body to prevent the first piston device from moving downward. The first limiting body is fixedly connected to the valve body by bolts.

[0018] An empty / loaded car valve for rail transit vehicles according to claim 1, characterized in that;

[0019] It also includes a check piston device, wherein the valve body is located below the second piston device and has a check chamber that communicates with the brake cylinder interface R, and the check chamber is equipped with the check piston device.

[0020] Furthermore, the check piston device includes a nut cover that is sealed to the valve body, a check piston is slidably connected to the upper part of the nut cover, and a spring is sleeved on the nut cover to drive the check piston to abut against the second piston device.

[0021] Furthermore, the second piston device is a single-diaphragm piston, which includes a second main rod and a second limiting body fixed to the valve body;

[0022] The top end of the second main rod contacts the balancing mechanism, the bottom end of the second main rod is slidably connected to the second limiting body, and an air passage is formed between the second limiting body and the second main rod that connects the brake cylinder interface R and the output emergency brake pressure interface Ev. The second main rod can protrude outside the second limiting body or retract inside.

[0023] Furthermore, the spring adjusting device includes two sets, each set of which is threadedly connected with an adjusting bolt. One end of the adjusting bolt is placed outside the valve body, and the other end is placed inside the cavity of the valve body.

[0024] In the above technical solution, the empty / loaded car valve for rail transit vehicles provided by this utility model has the following advantages:

[0025] This utility model designs an empty / loaded car valve for rail transit vehicles. By setting a spring adjustment device at the top of the valve body and installing a balancing mechanism at the bottom of the valve body cavity, the adjusting bolt of the balancing mechanism is set horizontally, the adjusting end of the adjusting bolt is exposed, and is coplanar with the brake cylinder interface R and the emergency brake pressure output interface Ev. This realizes that the adjusting bolt of the spring adjustment device and the balancing mechanism are placed on two adjacent surfaces of the valve body, so that the valve body has mounting surfaces in both the side and bottom directions. This not only improves the integration of the empty / loaded car valve, but also meets the needs of various installation methods.

[0026] The empty / loaded car valve balance lever balances the air pressure of the two sets of piston devices. The position of the balance lever fulcrum can be adjusted to regulate the ratio between the pressure of the two air springs and the emergency braking pressure. Simultaneously, it can adjust the minimum emergency braking pressure output to ensure train braking safety. Furthermore, it limits the maximum emergency braking pressure output under different air spring pressures, thus acting as a pressure limiter. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.

[0028] Figure 1 This is a schematic diagram of the internal structure of an empty / loaded car valve for rail transit vehicles disclosed in this utility model.

[0029] Figure 2 This is a front view of an empty / loaded car valve for rail transit vehicles disclosed in this utility model;

[0030] Figure 3 This is a front view of an empty / loaded car valve for rail transit vehicles disclosed in this utility model;

[0031] Figure 4 This is a left view of an empty / loaded vehicle valve for rail transit vehicles disclosed in this utility model.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Valve body; 2. Adjusting piston; 3. Piston bushing; 4. Gland; 5. Hex nut; 6. Adjusting bolt; 7. Adjusting nut; 8. Spring; 9. First main rod; 10. Gland; 11. Piston diaphragm; 12. Pressure ring; 13. First piston body; 14. Piston diaphragm; 15. Pressure ring; 16. First limit body; 17. Bolt; 18. Adjustable balance bar; 19. Adjusting roller; 20. Connecting rod; 21. Adjusting bolt; 22. Gland 23. Retaining ring; 24. Adjusting nut; 25. Nut cover; 26. Spring; 27. O-ring; 28. Check piston; 29. ​​O-ring; 30. Second limit body; 31. Return spring; 32. Retaining ring; 33. Cover; 34. Piston diaphragm; 35. Pressure ring; 36. Second main rod; 37. Fixed balance bar; 38. Cover; 39. Spring; 40. Cover; 41. Nut cover; 42. Adjusting nut; 43. Adjusting bolt;

[0034] 100, First cavity; 200, First piston device; 300, First spring adjusting device; 400, Second cavity; 500, Second piston device; 600, Second spring adjusting device; 700, Check piston device. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0036] See Figure 1-4 As shown;

[0037] A utility model discloses an empty / loaded car valve for rail transit vehicles, comprising: a valve body 1 having at least two cavities; a first piston device 200 and a second piston device 500 respectively installed in the cavities.

[0038] The valve body 1 has at least two air spring pressure ports T on one side and a brake cylinder port R and an emergency brake pressure output port Ev on the other side.

[0039] The valve body 1 is equipped with a spring adjustment device at the top of the cavity and a balancing mechanism for adjusting the first piston device 200 and the second piston device 500 at the bottom of the cavity. The adjusting bolt 21 of the balancing mechanism is set horizontally, and the adjusting end of the adjusting bolt 21 is coplanar with the brake cylinder interface R and the output emergency brake pressure interface Ev. This allows the adjusting bolts of the spring adjustment device and the balancing mechanism to be placed on two adjacent surfaces of the valve body 1, leaving the lower surface of the valve body 1 clear and providing a lower mounting surface. The valve body 1 has a hexahedral structure. After the lower surface of the valve body 1 is clear, it has mounting surfaces in both the side and bottom directions. The empty and loaded vehicle valve has a high degree of integration and can meet the needs of various installation methods.

[0040] like Figure 1 As shown, in this structure, two air ports connected to the air spring are opened on one side of the valve body 1: the first air spring pressure port T1 and the second air spring pressure port T2. The brake cylinder interface R and the emergency braking pressure output interface Ev are opened on the other side of the valve body 1, thus forming four air passage interfaces connected to the inner cavity of the valve body 1. Among them, three are air passage inlet interfaces, namely the brake cylinder interface R connected to the brake cylinder, the first air spring pressure port T1 connected to the air spring, and the second air spring pressure port T2 connected to the air spring. One air passage interface is an air outlet interface, namely the emergency braking pressure output interface Ev, which is used to connect to the relay valve.

[0041] The valve body 1 has an internal structure in which a first piston device 200 is installed in the first chamber 100 and a second piston device 500 is installed in the second chamber 400. Both piston devices have a main rod. The two piston devices are connected by a balancing mechanism at the bottom of the valve body 1, an adjustable balance rod 18 of the balancing mechanism, a connecting rod 20 in the middle of the valve body 1, and a fixed balance rod 37 at the top of the valve body 1. The first main rod 9 in the first chamber 100 is connected to a sealed spring adjustment device at the top. The fixed balance rod 37 in the second chamber 400 has a spring adjustment device at the top. The second piston device 200 is equipped with a second main rod 36 and a return spring 31. The lower part of the second main rod 36 is equipped with a check piston device 700.

[0042] See Figure 1 As shown:

[0043] Preferably, the adjusting bolt 21 extends to the bottom of the first piston device 200 via the extension rod and forms a balance fulcrum via the adjusting roller 19. The left and right swing state of the adjustable balance bar 18 is controlled by adjusting the position of the adjusting roller 19 horizontally, thereby controlling the first piston device 200 and the second piston device 500.

[0044] See Figure 1 As shown:

[0045] Preferably, the balancing mechanism includes an adjustable balance bar 18 and a fixed balance bar 37;

[0046] The adjustable balance bar 18 is horizontally positioned below the first piston device 200, with its lower surface in contact with the adjusting roller 19, one end of its upper surface in contact with the first piston device 200, and the other end in contact with the fixed balance bar 37 via the connecting rod 20.

[0047] The fixed balance bar 37 is rotatably connected to the valve body 1, and the end of the fixed balance bar 37 away from the connecting rod 20 is inserted between the second piston device 500 and the spring adjusting device.

[0048] Specifically, the balancing mechanism includes an adjustable balance bar 18, an adjusting roller 19, a connecting rod 20, an adjusting bolt 21, a pressure cap 22, a retaining ring 23, an adjusting nut 24, and a fixed balance bar 37.

[0049] The fixed balance bar 37 is positioned above the adjustable balance bar 18, and the connecting rod 20 is vertically connected between the adjustable balance bar 18 and the fixed balance bar 37 to enable them to move together.

[0050] The upper surface of the adjustable balance bar 18 away from the connecting rod 20 contacts the first piston device 200, and the lower surface of the adjustable balance bar 18 in the middle position contacts the adjusting roller 19. The fixed balance bar 37 away from the connecting rod 20 has one side in contact with the spring adjusting device and the other side in contact with the second piston device 200.

[0051] A retaining ring 23 and a pressure cap 22 are fixedly connected to the side wall of the valve body 1. The adjusting bolt 21 passes through the pressure cap 22, the retaining ring 23 and the side wall of the valve body 1, and can rotate relative to the valve body 1. The adjusting nut 24 is fitted on the outer end of the adjusting bolt 21 and locks the adjusting bolt 21 with the pressure cap 22. The inner end 21 of the adjusting bolt 21 is threadedly connected to an extension rod. The upper surface of the end of the extension rod is rotatably connected to an adjusting roller 19. By rotating the adjusting bolt 21, the extension rod extends or retracts, thereby changing the position of the balance fulcrum formed by the adjusting roller 19.

[0052] During operation, the first piston device 200 moves downward, and the adjustable balance bar 18 swings under the action of the balance fulcrum formed by the adjusting roller 19. The other end pushes the connecting rod 20 to move upward, thereby pushing the fixed balance bar 37 to rotate clockwise, thus pressing down the second piston device 200.

[0053] See Figure 1 As shown:

[0054] Preferably, an adjusting piston 2 is arranged between the first piston device 200 and the spring adjusting device 300, and a bushing 3 is installed on the cavity side wall of the valve body 1, with the bushing 3 in sealing contact with the adjusting piston 2.

[0055] Preferably, the first piston device 200 is a double-diaphragm piston, which includes a first main rod 9, wherein the bottom end of the first rod 9 is in contact with the balancing mechanism.

[0056] Specifically, the first piston device 200 includes a first main rod 9, two piston diaphragms 14 sleeved on the first main rod 9, a first piston body 13 spaced between the two piston diaphragms 14, and a pressure cap 10 that presses the piston diaphragms 14 onto the first piston body 13.

[0057] The outer ring of the piston diaphragm 14 is engaged with a pressure ring 12 and a pressure ring 15. The pressure ring 12 and the pressure ring 15 are engaged with the side wall of the first cavity 100 of the valve body 1 to prevent the first piston device 200 from moving upward. The top end of the first rod 9 is in contact with the adjusting piston 2 and the bottom end is in contact with the balancing mechanism.

[0058] The first air spring pressure port T1 is located above the piston diaphragm at the top of the first main rod 9, and the second air spring pressure port T2 is located above the piston diaphragm at the bottom.

[0059] See Figure 1 As shown:

[0060] Preferably, a first limiting body 16 is provided below the first piston device 200 on the valve body 1 to prevent the first piston device 200 from moving downward. The first limiting body 16 is fixedly connected to the valve body 1 by bolts 17. Specifically, the first limiting body 16 contacts the pressure ring 15 to prevent the pressure ring 15 from moving downward.

[0061] Preferably, it also includes a check piston device 700. The valve body 1 is located below the second piston device 500 and has a check chamber that communicates with the brake cylinder interface R. The check chamber is equipped with the check piston device 700, which enables the brake cylinder interface R to communicate with or close the first cavity 100 of the valve body 1.

[0062] See Figure 1 As shown:

[0063] Preferably, the check piston device 700 includes a nut cover 25 that is sealed to the valve body 1, a check piston 28 that is slidably connected to the upper part of the nut cover 25, and a spring 26 that drives the check piston 28 to abut against the second piston device 500 is sleeved on the nut cover 25.

[0064] Specifically, the check piston device 700 includes a nut cap 25, a spring 26, an O-ring 27, and a check piston 28;

[0065] The nut cap 25 is fixedly connected to the valve body 1. The overlapping position of the nut cap 25 and the valve body 1 is sealed by an O-ring 27. The check piston 28 is slidably connected to the upper protrusion of the nut cap 25. A spring 26 is fitted on the outer wall of the protrusion. The spring 26 is a compression spring. One end of the spring 26 abuts against the nut cap 25, and the other end abuts against the check piston 28. When the spring 26 extends, it drives the check piston 28 to abut against the second piston device 500, closing the brake air cylinder interface R. The emergency brake pressure output interface Ev is opened on one side of the second cavity 200.

[0066] See Figure 1 As shown:

[0067] Preferably, the second piston device 500 is a single-diaphragm piston, which includes a second main rod 36 and a second limiting body 30 fixed to the valve body 1.

[0068] The top end of the second main rod 36 contacts the balancing mechanism, and the bottom end of the second main rod 36 is slidably connected to the second limiting body 30. An air passage is formed between the second limiting body 30 and the second main rod 36, which connects the brake cylinder interface R and the emergency brake pressure output interface Ev. The second main rod 36 can protrude outside the second limiting body 30 or retract inside.

[0069] Specifically, the second piston device 500 includes an O-ring 29, a second limiting body 30, a return spring 31, a retaining ring 32, a pressure cap 33, a piston diaphragm 34, a pressure ring 35, and a second main rod 36.

[0070] Piston diaphragm 34 is sleeved on second main rod 36 and pressed onto second main rod 36 by pressure cap 33. The end of second main rod 36 is slidably connected to second limiting body 30. Second limiting body 30 is a limiting nut, which is fixed to valve body 1. When second main rod 36 slides downward, the end of second main rod 36 can protrude from the lower surface of second limiting body 30, so that the air passage between the outer wall of second limiting body 30 and second main rod 36 is opened. When second main rod 36 slides upward, the end of second main rod 36 can retract into second limiting body 30, and check piston 28 abuts against second limiting body 30, thereby closing the air passage.

[0071] The reset spring 31 is fitted outside the second main rod 36. The reset spring 31 is a compression spring. One end of the reset spring 31 abuts against the valve body 1, and the other end abuts against the pressure cap 33. When the reset spring 31 extends, it drives the second main rod 36 to move upward and reset, so that the end retracts into the second limiting body 30.

[0072] The second limiting body 30 and the valve body 1 overlap position are sealed and contacted by an O-ring 29;

[0073] A pressure ring 35 is engaged with the outer ring of the piston diaphragm 34. The pressure ring 35 is engaged with the second cavity 400 of the valve body 1 to prevent the second piston device 500 from moving downward.

[0074] The top end of the second main rod 36 contacts the fixed balance rod 37, and the other end contacts the check piston device 700.

[0075] See Figure 1 As shown:

[0076] Preferably, the spring adjusting device includes two sets, and each set of spring adjusting devices is threadedly connected with an adjusting bolt. One end of the adjusting bolt is placed outside the valve body 1, and the other end is placed inside the cavity of the valve body 1.

[0077] In a specific embodiment, the spring adjusting device includes a first spring adjusting device 300 and a second spring adjusting device 600, and the valve body 1 includes a first cavity 100 on which the first piston device 200 is installed and a second cavity 400 on which the second piston device 600 is installed.

[0078] The first spring adjusting device 300 is positioned above the first piston device 200. The first spring adjusting device 300 includes a pressure cap 4, a hexagonal nut 5, an adjusting bolt 6, an adjusting nut 7, and a spring 8.

[0079] During assembly, the hexagonal nut 5 is threadedly connected to the top of the first cavity 100 of the valve body 1. An adjusting bolt 6 is threadedly connected to the hexagonal nut 5. An adjusting nut 7 is threadedly connected to the adjusting bolt 6 and is used to lock the adjusting bolt 6 in conjunction with the hexagonal nut 5. The pressure cap 4 is slidably connected to the adjusting piston 2. The spring 8 is a compression spring, which is sleeved on the outside of the adjusting piston 2. One end abuts against the adjusting piston 2, and the other end abuts against the pressure cap 4. The spring 8 extends to support the adjusting piston 2 to move downward and push the first piston device 300, thereby adjusting the first piston device 300.

[0080] The second spring adjusting device 600 is positioned above the second piston device 500. The second spring adjusting device 500 includes a pressure cap 38, a spring 39, a pressure cap 40, a nut pressure cap 41, an adjusting nut 42, and an adjusting bolt 43.

[0081] During assembly, the nut cover 41 is threadedly connected to the top of the second cavity 400 of the valve body 1. An adjusting bolt 43 is threadedly connected to the nut cover 41. An adjusting nut 42 is threadedly connected to the adjusting bolt 43 and is used to lock the adjusting bolt 43 in conjunction with the nut cover 41. The spring 39 is a compression spring, with its top end in contact with the cover 40 and its bottom end in contact with the cover 38. The upper surface of the cover 40 is in contact with the adjusting bolt 43, and the lower surface of the cover 38 is in contact with the fixed balance bar 37. When the spring 39 extends, it can drive the fixed balance bar 37 to rotate clockwise and move the second main rod 36 of the second piston device 600 downward, thereby adjusting the second piston device 600.

[0082] In the above technical solution, the present invention provides an empty / loaded car valve for rail transit vehicles, the working principle of which is as follows:

[0083] See Figure 1 As shown:

[0084] ① When the air spring pressures of T1 and T2 are both 0, the adjusting bolt 6 (bolt B1), adjusting nut 7, pressure cap 4, spring 8, and adjusting piston 2 are in contact with the first main rod 9. By adjusting the balance bar 18, connecting rod 20, and fixing the balance bar 37, a downward force is generated on the second main rod 36. The second main rod 36 pushes the lower check piston 28, so that the total air pressure R is connected to the emergency braking pressure Ev. The Ev pressure is balanced with the force generated by the first main rod 9. Therefore, an emergency braking pressure of AW0 can be adjusted as the minimum Ev pressure output. Even when the air spring pressure is 0, the safety of the train braking system can still be guaranteed.

[0085] ② When the air spring pressures of T1 and T2 are AW3 (heavy load), the air spring pressures of T1 and T2 act on the double diaphragm piston device 200 to push the first main rod 9. By adjusting the balance bar 18, connecting rod 20, and fixing the balance bar 37, the force balance is generated on the second main rod 36. By adjusting the bolt 43 (bolt B2), adjusting nut 42, pressure cap 40, spring 39, pressure cap 38, and fixing the balance bar 37, the maximum force of the second main rod 36 is limited, so that the output Ev pressure is the emergency braking pressure of AW3 (heavy load), which plays a pressure limiting role and ensures that the output pressure Ev will not exceed the maximum braking force.

[0086] ③ By limiting the brake cylinder pressure Ev between the minimum (AW0) and the maximum (AW3) through ① and ② above, the ratio of the total force of the air spring pressures T1 and T2 to the emergency braking pressure Ev can be adjusted by pushing the adjusting roller 19 through adjusting bolt 21 (bolt B3), that is, adjusting the slope of the control curve from AW0 to AW3.

[0087] The foregoing description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An empty / loaded car valve for rail transit vehicles, comprising: A valve body (1) having at least two cavities, and a first piston device (200) and a second piston device (500) respectively installed in the cavities, characterized in that: The valve body (1) has at least two air spring pressure ports T on one side and a brake cylinder port R and an emergency brake pressure output port Ev on the other side. The valve body (1) is provided with a spring adjustment device at the top of the cavity and a balance mechanism for adjusting the first piston device (200) and the second piston device (500) at the bottom of the cavity. The adjustment bolt (21) of the balance mechanism is horizontally set, and the adjustment end of the adjustment bolt (21) is coplanar with the brake cylinder interface R and the output emergency brake pressure interface Ev.

2. The empty / loaded car valve for rail transit vehicles according to claim 1, characterized in that... ； The adjusting bolt (21) extends below the first piston device (200) via an extension rod and forms a balance fulcrum via an adjusting roller (19).

3. The empty / loaded car valve for rail transit vehicles according to claim 2, characterized in that... ； The balancing mechanism includes an adjustable balance bar (18) and a fixed balance bar (37); The adjustable balance bar (18) is horizontally positioned below the first piston device (200), with its lower surface in contact with the adjusting roller (19), one end of its upper surface in contact with the first piston device (200), and the other end in contact with the fixed balance bar (37) via the connecting rod (20). The fixed balance bar (37) is rotatably connected to the valve body (1), and the end of the fixed balance bar (37) away from the connecting rod (20) is inserted between the second piston device (500) and the spring adjusting device.

4. The empty / loaded car valve for rail transit vehicles according to claim 1, characterized in that... ； An adjusting piston (2) is provided between the first piston device (200) and the spring adjusting device (300), and a bushing (3) is installed on the side wall of the cavity of the valve body (1), and the bushing (3) is in sealing contact with the adjusting piston (2).

5. A valve for empty / loaded cars in rail transit vehicles according to claim 1 or 4, characterized in that... ； The first piston device (200) is a double-diaphragm piston, which includes a first main rod (9), the bottom end of which is in contact with the balancing mechanism.

6. A valve for empty / loaded cars in rail transit vehicles according to claim 5, characterized in that... ； The valve body (1) is provided with a first limiting body (16) below the first piston device (200) to prevent the first piston device (200) from moving downward. The first limiting body (16) is fixedly connected to the valve body (1) by bolts (17).

7. A valve for empty / loaded cars in rail transit vehicles according to claim 1, characterized in that... ； It also includes a check piston device (700), wherein the valve body (1) is located below the second piston device (500) and has a check chamber that communicates with the brake cylinder interface R, and the check chamber is equipped with the check piston device (700).

8. A valve for empty and loaded cars in rail transit vehicles according to claim 7, characterized in that; The check piston device (700) includes a nut cover (25) that is sealed to the valve body (1). A check piston (28) is slidably connected to the upper part of the nut cover (25), and a spring (26) is sleeved on the nut cover (25) to drive the check piston (28) to abut against the second piston device (500).

9. A valve for empty / loaded cars in rail transit vehicles according to claim 1 or 7, characterized in that... ； The second piston device (500) is a single-diaphragm piston, which includes a second main rod (36) and a second limiting body (30) fixed to the valve body (1); The top end of the second main rod (36) contacts the balance mechanism, the bottom end of the second main rod (36) is slidably connected to the second limiting body (30), and an air passage is formed between the second limiting body (30) and the second main rod (36) that connects the brake cylinder interface R and the output emergency brake pressure interface Ev. The second main rod (36) can protrude outside the second limiting body (30) or retract inside.

10. A valve for empty / loaded cars in rail transit vehicles according to claim 1, characterized in that... ； The spring adjustment device includes two sets, and each set of the spring adjustment device is threadedly connected with an adjustment bolt. One end of the adjustment bolt is placed outside the valve body (1), and the other end is placed inside the cavity of the valve body (1).

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