Asymmetric reversing valve, load control unit and rail transit braking system

Abstract

The invention discloses an asymmetric reversing valve, a load control unit and a rail transit braking system and aims to solve the problems that an existing rail transit braking system is controlled by an electromagnetic valve, the cost of the electromagnetic reversing valve (or a proportional pressure reducing valve) is high, the control logic of a vehicle can be increased, the reliability of the electromagnetic valve depends on the electrical performance of the electromagnetic valve, and the reliability of the electromagnetic valve is influenced. And the reliability is low. The asymmetric reversing valve is used for asymmetrically and selectively communicating two air inlets with an outlet, the load control unit is used for the rail transit braking system, and the load control unit is used for comparing the pressure difference between a constant pressure source and an air spring through the asymmetric reversing valve; and the load control unit generates an air pressure signal source of the pneumatic control braking unit according to the asymmetric comparison of the asymmetric reversing valve. When the air spring works normally, the device can select proper braking force according to the load of the air spring, and can also select the maximum braking force for emergency braking after the air spring fails.

Description

Technical Field

[0001] The invention relates to the field of rail transit braking, and more specifically, to an asymmetric reversing valve. Background Art

[0002] The urban rail transit braking system consists of an air supply unit, a pneumatic brake unit, an electronic brake control unit, an auxiliary brake control unit, and brakes, among which the pneumatic brake unit and the electronic brake control unit are important components of the braking system. The electro-pneumatic brake system has been maturely applied to rail transit vehicles in major cities. The pneumatic brake unit selects the indicated braking force according to the air pressure of the air spring used in the rail transit vehicle. The greater the load of the vehicle, the greater the air pressure of the air spring, and the braking force increases accordingly, thereby providing a good riding experience.

[0003] The rail transit braking system has an emergency braking function. Emergency braking is all air braking, which is generated by the loss of power to the emergency solenoid valve. The pneumatic control braking unit receives the real-time load air pressure value and outputs the corresponding emergency braking air pressure value. When the air spring ruptures, the pneumatic control braking unit outputs the minimum load emergency braking air pressure value.

[0004] The existing rail transit braking system is controlled by solenoid valves. The solenoid valve reversing valve (or proportional pressure reducing valve) is expensive and will increase the vehicle's own control logic. In addition, the reliability of the solenoid valve depends on its electrical performance and has low reliability.

[0005] The present application aims to improve a load control unit of a rail transit braking system, thereby increasing the reliability and cost of the load control unit. Summary of the invention

[0006] The present invention overcomes the shortcomings of the existing rail transit braking system that adopts solenoid valve control, the high cost of the solenoid valve reversing valve (or proportional pressure reducing valve), and the increase of the vehicle's own control logic, and the reliability of the solenoid valve depends on its electrical performance and has low reliability. An asymmetric reversing valve, a load control unit and a rail transit braking system are provided. By improving the structure to be a pure mechanical structure, the reliability of the load control unit is improved and the cost is reduced.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: An asymmetric reversing valve comprises a valve body and a valve core, wherein the valve body is provided with a low-pressure air inlet, a high-pressure air inlet and an air outlet, the valve body is hollow and forms a piston cavity, the valve core is slidably connected in the piston cavity and is sealed with the piston cavity, the valve core separates the piston cavity into a low-pressure air pressure chamber and a high-pressure air pressure chamber, the middle part of the valve core is provided with two annular grooves, the annular grooves and the piston cavity form a low-pressure connecting cavity and a high-pressure connecting cavity, the valve body is provided with a low-pressure air pressure channel connected to the low-pressure air pressure chamber, a low-pressure connecting channel connected to the low-pressure connecting cavity, and a high-pressure connecting cavity connected to the high-pressure air pressure chamber The high-pressure air pressure channel, the high-pressure connecting channel connected to the high-pressure connecting chamber, the low-pressure air pressure channel and the low-pressure connecting channel are connected to the low-pressure air inlet, the high-pressure air pressure channel and the high-pressure connecting channel are connected to the high-pressure air inlet, the air outlet is located between the low-pressure connecting chamber and the high-pressure connecting chamber, the side wall area of ​​the valve core at the low-pressure air pressure chamber is larger than the side wall area of ​​the high-pressure air pressure chamber, according to the air pressure difference between the low-pressure air inlet and the high-pressure air inlet, the valve core moves to connect the air outlet with the low-pressure connecting chamber or the high-pressure connecting chamber, thereby connecting the air outlet with the low-pressure air inlet or the high-pressure air inlet.

[0008] The effect of the asymmetric reversing valve is that its valve body design includes two air inlets and one air outlet, and the two air inlets present asymmetric characteristics. Through the coordination and setting between the valve body and the valve core, when the air pressure value of one of the so-called low-pressure air inlets is multiplied by a fixed coefficient greater than one, and the result exceeds the air pressure of the other so-called high-pressure air inlet, the air outlet is connected to the low-pressure air inlet. It is worth noting that at this time, the air pressure in the low-pressure air inlet may actually be lower than the air pressure in the high-pressure air inlet, thus reflecting its "asymmetric" characteristics.

[0009] Specifically, the valve core is provided with a low-pressure air chamber and a high-pressure air chamber at both ends of its axial direction, and the two are connected to the aforementioned low-pressure air inlet and high-pressure air inlet respectively. The air pressure of the low-pressure air chamber is the same as the air pressure of the low-pressure air inlet, and the air pressure of the high-pressure air inlet and the high-pressure air chamber are also the same. However, since the side wall area of ​​the valve core at the low-pressure air chamber is larger than the side wall area at the high-pressure air chamber, where the area is the projected area of ​​the side wall in the axial direction of the valve core, F (pressure) = P (air pressure) × S (area). Since the area at the low-pressure air chamber is larger than the area at the high-pressure air chamber, even if the air pressure at the low-pressure air inlet is lower than the air pressure at the high-pressure air inlet, within a certain value range, the valve core will still move to the side of the high-pressure air chamber.

[0010] Through the low-pressure connecting channel and the high-pressure connecting channel, the low-pressure air inlet and the high-pressure air inlet are connected with the low-pressure connecting chamber and the high-pressure connecting chamber. With the displacement of the valve core, the air outlet located between the two annular grooves or the low-pressure connecting chamber and the high-pressure connecting chamber is connected with the low-pressure connecting chamber or the high-pressure connecting chamber, thereby realizing the connection between the low-pressure air inlet or the high-pressure air inlet and the air outlet.

[0011] For example, if the gas pressure input by the low-pressure inlet is aw0, and the gas pressure input by the high-pressure inlet is aw3, aw3>aw0, and the coefficient of the asymmetric reversing valve in the present application is k, then when aw0×k is greater than aw3, the gas outlet is connected to the low-pressure inlet, and when aw0×k is less than aw3, the gas outlet is connected to the high-pressure inlet.

[0012] Preferably, the valve body protrudes inward to form a limit flange, and the valve core is provided with a first abutting surface and a second abutting surface in the movement direction of the valve core. When the valve core reaches the stroke limit, the valve core is respectively in contact with the first abutting surface or the second abutting surface. The limit flange limits the valve core, and the outer wall of the valve core is provided with a protruding structure, and the limit flange is located between the two protruding structures. When the limit flange is in contact with a protruding structure, the valve core reaches the stroke limit.

[0013] A load control unit for a rail transit braking system, comprising a pressure reducing valve, an asymmetric reversing valve, a symmetric reversing valve and an averaging valve as described above; The two air inlets of the averaging valve are respectively connected to the air springs on both sides of the rail transit, and the air outlet of the averaging valve is connected to an air inlet of the symmetrical reversing valve and a low-pressure air inlet of the asymmetrical reversing valve; Another air inlet of the symmetrical reversing valve is communicated with the air outlet of the asymmetrical reversing valve, and the air outlet of the symmetrical reversing valve is output to the air-controlled brake unit of the rail transit brake system; The main air duct of the rail transit brake system is connected to the air inlet of the pressure reducing valve, and the air outlet of the pressure reducing valve is connected to the high-pressure air inlet of the asymmetric reversing valve.

[0014] The function of the load control unit is to output the corresponding air pressure value to the pneumatic control braking unit according to the load borne by the rail transit vehicle, so that the pneumatic control braking unit can output the corresponding braking force according to the received air pressure signal. In order to provide a better riding experience, rail transit vehicles combine the pressure of the air spring with the braking force of the braking system. The braking force is smaller at low loads and increases at high loads, thereby obtaining a similar braking feel under various working conditions. If the air springs on one or both sides fail, the air pressure generated by the air springs quickly returns to zero, and the braking force as a slave control parameter also tends to return to zero. Therefore, a load control unit is set between the air springs and the braking system.

[0015] The load control unit has three input ports and one output port to the brake system, two of which are connected to the air springs on the left and right sides respectively, and the other is connected to the main air duct of the brake system. The function is realized by the load control unit composed of a pressure reducing valve, an asymmetric reversing valve, a symmetric reversing valve and an averaging valve. In simple terms, the air pressure of the two air springs is averaged and adjusted to a stable low-pressure output through the pressure reducing valve and compared through the asymmetric reversing valve. According to the setting of the asymmetric reversing valve, the air pressure difference between the low-pressure air inlet and the high-pressure air inlet is compared, and the corresponding output is output to the brake system.

[0016] Preferably, a test connector for detecting air pressure is provided on the channel connecting the high-pressure air inlet of the asymmetric reversing valve and the air outlet of the pressure reducing valve. The test connector is used to be connected to the load control unit to facilitate detection and maintenance.

[0017] Preferably, a differential pressure valve is provided between the air springs on both sides, and the differential pressure valve limits the air pressure difference between the two air springs. `When the air spring on one side fails, the pressure of the rail transit vehicle partially migrates to the air spring on the other side, causing its output to exceed the preset value. Therefore, by providing a differential pressure valve, the air pressure difference between the two air springs is limited. If the air pressure of one air spring disappears, the maximum air pressure output by the other air spring does not exceed the preset value of the differential pressure valve.

[0018] Preferably, the upper limit of the air pressure generated by the air outlet of the pressure reducing valve is the air pressure value of the air spring under the heavy load condition of the rail vehicle. The air pressure output by the main air duct fluctuates and has low precision. By setting a pressure reducing valve, the air pressure output by the main air duct can be suppressed to the air pressure value of the air spring under the heavy load condition of the rail vehicle, thereby simulating the braking force of the rail vehicle under heavy load conditions.

[0019] Preferably, the air outlet of the averaging valve is also connected to the air inlet of the one-way valve, and the air outlet of the one-way valve is connected to the air outlet of the symmetrical reversing valve and the two ports of the three-way pipe and output to the air-controlled braking unit. The direction of the one-way valve is from the averaging valve to the three-way pipe. This feature is to avoid the problem that during the switching process of the asymmetrical reversing valve and the symmetrical reversing valve, the valve core covers the air outlet, causing the air pressure of the asymmetrical reversing valve and the symmetrical reversing valve to disappear in a short period of time, resulting in the air pressure value received by the air-controlled braking unit being 0, and the braking force of the air-controlled braking unit disappearing.

[0020] When the air spring on one side fails and the air pressure returns to 0, the air pressure output by the average valve drops to half of the upper limit of the air pressure output by the differential pressure valve. During the switching process between the asymmetric reversing valve and the symmetric reversing valve, the valve core blocks the air outlet, resulting in the air pressure value of the air outlet being 0, and the airflow at the air outlet of the average valve passes through the one-way valve and is output to the air control braking unit; when the asymmetric reversing valve and the symmetric reversing valve are switched, the one-way valve can no longer pass through the one-way valve due to the system back pressure, and the airflow output by the symmetric reversing valve enters the air control braking unit. The structure can raise the bottom of the air pressure curve received by the air control braking unit, thereby maintaining the stability of the braking force and improving the safety of rail transit.

[0021] A rail transit braking system comprises the load control unit for the rail transit braking system as described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) Through the asymmetric area design at both ends of the valve core (the low-pressure side has a larger projected area), a unique response logic is achieved in which the low-pressure inlet pressure is amplified by a coefficient and compared with the high-pressure side. Even if the actual low-pressure air pressure (aw0) is lower than the high-pressure air pressure (aw3), the air path switching can still be triggered when aw0×k>aw3, breaking through the physical limitations of traditional symmetrical reversing valves and providing precise control for special working conditions; (2) The average pressure of the air springs on both sides is collected through the averaging valve, and the dynamic comparison between the asymmetric reversing valve and the total air duct pressure reduction pressure is combined. When the air springs on one or both sides fail, the system automatically switches to the backup pressure source (total air duct pressure reduction value), ensuring that the braking system always obtains the effective load signal, thus solving the major safety hazard of the traditional system where the braking force returns to zero due to air spring failure. (3) A differential pressure valve is used to limit the pressure difference of the air springs on both sides (to prevent failure of one side from causing overpressure on the other side), and a pressure reducing valve is used to stabilize the high pressure of the main air duct to the threshold of heavy-load conditions. The dual pressure control mechanism not only ensures the system response accuracy, but also avoids pressure shock under extreme conditions, making the braking force output curve smoother and more stable; (4) Through the linkage design of the one-way valve and the symmetrical reversing valve, the one-way valve is used to maintain the air pressure output during the valve core switching process, eliminating the air pressure "dead zone" at the moment of switching of the traditional reversing valve, ensuring the continuity of the braking command, which is particularly suitable for rail transit scenarios with extremely high requirements for braking smoothness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of an asymmetric reversing valve of the present invention; Figure 2 It is a schematic diagram of the valve core of the asymmetric reversing valve of the present invention moving rightward; Figure 3Schematic diagram of the asymmetric reversing valve of the present invention when the valve core moves leftward; Figure 4 is a schematic diagram of a rail transit braking system of the present invention; Figure 5 is a schematic diagram of a load control unit of the present invention; Figure 6 It is a schematic diagram of another embodiment of the load control unit of the present invention. DETAILED DESCRIPTION

[0024] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present disclosure, and do not specifically refer to any part or element in the present disclosure and should not be understood as limitations on the present disclosure.

[0028] In the present disclosure, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present disclosure can be determined according to specific circumstances, and they cannot be understood as limitations on the present disclosure.

[0029] Example 1: Structure and working principle of asymmetric reversing valve Ginseng Figures 1 to 3 As shown, the asymmetric reversing valve comprises a valve body 1 and a valve core 2. The valve body 1 is provided with a low-pressure air inlet P1, a high-pressure air inlet P2 and an air outlet A. The interior of the valve body 1 is hollow to form a piston chamber 3. The valve core 2 is slidably sealed in the piston chamber 3 and divides it into a low-pressure air chamber 4 and a high-pressure air chamber 5.

[0030] In some embodiments, the valve body is a detachable structure, including a middle portion, a front portion and a rear portion of the valve body. The middle portion of the valve body is a hollow tube with a sleeve installed inside. The valve core actually fits with the sleeve to slide.

[0031] Two annular grooves (left annular groove 6L and right annular groove 6R) are provided in the middle of the valve core 2. A low-pressure communication chamber 7 is formed between the left annular groove 6L and the inner wall of the piston chamber 3, and a high-pressure communication chamber 8 is formed between the right annular groove 6R and the inner wall of the piston chamber 3. The valve body 1 is provided with the following channels: Low-pressure air passage 9: connecting the low-pressure air inlet P1 and the low-pressure air chamber 4; Low-pressure connecting channel 10: connecting the low-pressure air inlet P1 with the low-pressure connecting chamber 7; High-pressure air channel 11: connecting the high-pressure air inlet P2 and the high-pressure air chamber 5; The high-pressure connecting passage 12 connects the high-pressure air inlet P2 with the high-pressure connecting chamber 8 .

[0032] The axial projection area S1 of the valve core 2 on the low pressure chamber 4 side is larger than the projection area S2 on the high pressure chamber 5 side (S1>S2, S1=k×S2). Figure 2 As shown in FIG. 1 , when the air pressure at the low-pressure air inlet P1 is aw0 and the air pressure at the high-pressure air inlet P2 is aw3, if aw0×k>aw3, the valve core 2 moves rightward to connect the air outlet A to the low-pressure connecting chamber 7; otherwise, Figure 3 As shown, the valve core 2 moves leftward to connect the air outlet A to the high-pressure communication chamber 8. A limit flange 13 is provided in the valve body 1, and a protruding structure 14 is provided on the valve core 2. When the protruding structure 14 contacts the limit flange 13, the valve core 2 reaches the stroke limit.

[0033] Example 2: Implementation of the load control unit Ginseng Figure 4 and Figure 5 As shown, the load control unit includes an average valve 15, a symmetrical reversing valve 16, an asymmetrical reversing valve 17 of embodiment 1 and a pressure reducing valve 18. The specific connection relationship is as follows: The two air inlets of the averaging valve 15 are respectively connected to the left and right air springs 19L and 19R of the rail transit vehicle, and the air outlet thereof is simultaneously connected to the air inlet X of the symmetrical reversing valve 16 and the low-pressure air inlet P1 of the asymmetrical reversing valve 17 through the pipeline 20; Another air inlet Y of the symmetrical reversing valve 16 is connected to the air outlet A of the asymmetrical reversing valve 17, and the air outlet B thereof is output to the air control braking unit 22 via the three-way pipe 21; The main air duct 23 is depressurized by the pressure reducing valve 18 and then output to the high-pressure air inlet P2 of the asymmetric reversing valve 17. The pressure reducing valve 18 sets the upper limit of the output air pressure to the rated value of the air spring 19 when the vehicle is heavily loaded.

[0034] Embodiment 3: Ginseng Figure 6 As shown, a test connector 25 is provided on the pipeline 24 between the high-pressure air inlet P2 and the pressure reducing valve 18 for connecting to the air pressure detection equipment. A differential pressure valve 26 is added between the air springs 19 on both sides, and the pressure difference threshold is set to ΔP=150kPa. When the air spring on one side fails, the air pressure on the other side is limited to ΔP. In addition, the air outlet of the averaging valve 15 is also connected to the inlet of the one-way valve 27, and the outlet of the one-way valve 27 is connected to the three-way pipe 21. When the asymmetric reversing valve 17 is switched, the one-way valve 27 maintains the air pressure of the air-controlled braking unit 22 not lower than the output value of the averaging valve 15 to avoid interruption of the braking force.

[0035] In some embodiments, the load control unit is modularly configured, with an air inlet connected to the two air springs, an air inlet connected to the main air duct, and an air outlet connected to the air control braking unit 22 .

[0036] Under normal working conditions, the air spring 19 outputs air pressure aw0 to aw3, which is averaged by the averaging valve 15 and output to P1 of the asymmetric reversing valve 17. The pressure reducing valve 18 outputs aw3 to P2. Because aw0×k is greater than aw3, the asymmetric reversing valve 17 maintains low-pressure communication, and the air outlet A outputs low pressure to the Y port of the symmetric reversing valve 16. Finally, the pneumatic control braking unit 22 obtains a braking signal equivalent to the air spring.

[0037] When the left air spring fails and the output air pressure is 0, the differential pressure valve 26 limits the right air pressure to no more than 150kPa, and the average valve 15 outputs 75kPa. At this time, the output air pressure × k = < aw3, and the asymmetric reversing valve 17 switches to output high pressure to ensure that the braking force does not drop to zero. During the switching process, the one-way valve 27 temporarily outputs 75kpa to maintain braking until the symmetric reversing valve 16 completes the switching.

[0038] This embodiment realizes uninterrupted switching of the braking force when the air spring fails through the force balance design of the asymmetric reversing valve and the linkage of the differential pressure valve and the one-way valve.

[0039] The embodiments described above are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. An asymmetric reversing valve, characterized in that: The invention comprises a valve body and a valve core, wherein the valve body is provided with a low-pressure air inlet, a high-pressure air inlet and an air outlet, the valve body is hollow and forms a piston cavity, the valve core is slidably connected in the piston cavity and is sealed with the piston cavity, the valve core divides the piston cavity into a low-pressure air pressure chamber and a high-pressure air pressure chamber, the middle part of the valve core is provided with two annular grooves, the annular grooves and the piston cavity form a low-pressure connecting cavity and a high-pressure connecting cavity, the valve body is provided with a low-pressure air pressure channel connected to the low-pressure air pressure chamber, a low-pressure connecting channel connected to the low-pressure connecting cavity, and a high-pressure air pressure channel connected to the high-pressure air pressure chamber , a high-pressure connecting channel connected to the high-pressure connecting chamber, the low-pressure air pressure channel and the low-pressure connecting channel are connected to the low-pressure air inlet, the high-pressure air pressure channel and the high-pressure connecting channel are connected to the high-pressure air inlet, the air outlet is located between the low-pressure connecting chamber and the high-pressure connecting chamber, the side wall area of ​​the valve core at the low-pressure air pressure chamber is larger than the side wall area at the high-pressure air pressure chamber, according to the air pressure difference between the low-pressure air inlet and the high-pressure air inlet, the valve core moves to connect the air outlet with the low-pressure connecting chamber or the high-pressure connecting chamber, thereby connecting the air outlet with the low-pressure air inlet or the high-pressure air inlet.

2. An asymmetric reversing valve according to claim 1, characterized in that: The valve body protrudes inward to form a limited position flange, and the valve core is provided with a first abutting surface and a second abutting surface in the moving direction of the valve core. When the valve core reaches the stroke limit, the valve core fits with the first abutting surface or the second abutting surface respectively.

3. A load control unit for a rail transit braking system, characterized in that: It comprises a pressure reducing valve, an asymmetric reversing valve as claimed in any one of claims 1 or 2, a symmetric reversing valve and an averaging valve; The two air inlets of the averaging valve are respectively connected to the air springs on both sides of the rail transit, and the air outlet of the averaging valve is connected to an air inlet of the symmetrical reversing valve and a low-pressure air inlet of the asymmetrical reversing valve; Another air inlet of the symmetrical reversing valve is communicated with the air outlet of the asymmetrical reversing valve, and the air outlet of the symmetrical reversing valve is output to the air-controlled brake unit of the rail transit brake system; The main air duct of the rail transit brake system is connected to the air inlet of the pressure reducing valve, and the air outlet of the pressure reducing valve is connected to the high-pressure air inlet of the asymmetric reversing valve.

4. A load control unit for a rail transit braking system according to claim 3, characterized in that: A test connector for detecting air pressure is provided on a channel connecting the high-pressure air inlet of the asymmetric reversing valve and the air outlet of the pressure reducing valve.

5. The load control unit for a rail transit braking system according to claim 3, characterized in that: A differential pressure valve is also provided between the air springs on both sides, and the differential pressure valve limits the air pressure difference between the two air springs.

6. The load control unit for a rail transit braking system according to claim 3, characterized in that: The upper limit of the air pressure generated by the air outlet of the pressure reducing valve is the air pressure value of the air spring under the heavy load condition of the rail vehicle.

7. A load control unit for a rail transit braking system according to any one of claims 3 to 6, characterized in that: The air outlet of the averaging valve is also connected to the air inlet of the one-way valve. The air outlet of the one-way valve is connected to the air outlet of the symmetrical reversing valve and two ports of the three-way pipe and outputs to the air control braking unit.

8. A rail transit braking system, characterized in that: It comprises a load control unit for a rail transit braking system as claimed in claim 7.

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