A pressure boosting structure of a brake valve

Abstract

This invention provides a pressure boosting structure for a brake valve, belonging to the technical field of brake valves. It solves the problem of poor compactness in existing brake valve structures. In this pressure boosting structure, the inner wall of the valve body has at least one pair of inlet holes for oil intake and one pair of brake fluid outlet holes. A piston assembly is slidably connected within the valve body. A sealing ring, stretched and tightened on the inner peripheral wall of the valve body, is fitted over the piston assembly, with a gap between the sealing ring and the piston assembly for oil passage. The pressure boosting structure includes an exhaust hole on the inner wall of the valve body, the outer end of which communicates with the inlet hole. The diameter of the exhaust hole is smaller than that of the inlet hole, and the exhaust hole is located between the inlet hole and the brake fluid outlet. The sealing ring is located axially along the valve body between the inlet hole and the exhaust hole. When the piston assembly moves towards the brake fluid outlet and approaches the exhaust hole, the piston assembly can abut against the sealing ring to block the communication between the inlet hole and the brake fluid outlet. This pressure boosting structure of the brake valve has the advantage of a compact structure.

Description

Technical Field

[0001] This invention belongs to the field of brake valve technology and relates to a pressure boosting structure for a brake valve. Background Technology

[0002] The braking system of wheeled engineering vehicles typically uses a fully hydraulic brake valve as the core control element. The brake valve includes an oil inlet and a working oil port. In the initial state, the oil inlet and the working oil port are connected. When the driver presses the brake pedal, the piston moves forward, closing the oil inlet and forming a pressure chamber in the valve body. The piston continues to move forward, squeezing the oil in the pressure chamber, which increases the oil pressure. The high-pressure oil is output to the wheel brake through the working oil port, generating braking force.

[0003] When installing the brake valve, the brake valve is assembled with the connecting pipeline. That is, the oil inlet is connected to the oil tank or oil cup through the connecting pipeline, and the brake fluid port is connected to the brake through the connecting pipeline. There is air in the connecting pipeline. When the brake system is filled with oil for the first time, the air in the connecting pipeline will enter the valve body with the oil. Due to the compressibility of air, when the piston is squeezed, the air in the valve body will be compressed first. This causes a large amount of brake pedal travel to be wasted on compressing gas instead of building pressure, which directly leads to the problem of sluggish brake response. Therefore, the first "bleeding" after the initial installation of the brake system or after a major overhaul is crucial.

[0004] To achieve the first "venting" of the braking system after initial installation or large-scale maintenance, the existing technology adds an exhaust valve to the valve body of the existing fully hydraulic brake valve. For example, Chinese patent literature discloses a hydraulic brake valve and its venting process method (application number CN202111589761.1). Adding an exhaust valve to the existing brake valve undoubtedly increases the size of the brake valve, that is, the structural compactness of the brake valve is poor. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the prior art by proposing a pressure boosting structure for a brake valve, thereby solving the problem of sluggish braking response and improving the structural compactness of the brake valve.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A pressure-boosting structure for a brake valve, the brake valve including a valve body, the inner wall of the valve body having at least one pair of oil inlet holes for oil inlet and brake fluid outlet holes for brake fluid outlet, a piston assembly slidably connected within the valve body, the piston assembly being fitted with a sealing ring tightened on the inner peripheral wall of the valve body, and a gap for oil fluid to pass through between the sealing ring and the piston assembly, characterized in that the pressure-boosting structure includes an exhaust hole on the inner wall of the valve body, the outer end of the exhaust hole communicating with the oil inlet hole, the diameter of the exhaust hole being smaller than the diameter of the oil inlet hole, the exhaust hole being located between the oil inlet hole and the brake fluid outlet holes, the sealing ring being located axially along the valve body between the oil inlet hole and the exhaust hole, when the piston assembly moves toward the brake fluid outlet holes and approaches the exhaust hole, the piston assembly can abut against the sealing ring to block the communication between the oil inlet hole and the brake fluid outlet holes.

[0008] This application is based on the working principle of existing brake valves and combines the flow path of the hydraulic fluid and the movement trajectory of the piston assembly. During the initial braking after the initial installation of the braking system or after major repairs, venting occurs through the vent hole at the initial stage of hydraulic fluid entry, minimizing the involvement of gas in the subsequent pressure build-up of the brake valve. This structure improves the timely braking response of the subsequent brake valves. The specific venting process during braking is as follows: Before the initial braking, there is no hydraulic fluid in the connecting lines and brake valves. At this time, the pressure in the inlet line and the brake valve is basically the same. When the driver depresses the brake pedal... The piston assembly moves along the valve body, and hydraulic fluid enters the valve body through the inlet port via the connecting pipe. As hydraulic fluid enters and the piston moves, the pressure inside the valve body increases, while the pressure in the inlet pipe remains constant. Since gas flows from high-pressure areas to low-pressure areas, and because the vent port's diameter is smaller than the inlet port's diameter, and the vent port is located between the inlet port and the brake fluid port, hydraulic fluid enters through the inlet port, and gas in the hydraulic fluid is expelled through the vent port. When the piston assembly comes into contact with the sealing ring, blocking the connection between the inlet port and the brake fluid port, hydraulic fluid intake stops. The piston assembly drives the sealing ring to continue moving. When the oil inlet is blocked by the sealing ring but the sealing ring has not yet passed the vent hole, the vent hole is still connected to the pressure chamber. Therefore, as the piston moves, the vent hole continues to discharge the gas in the pressure chamber until the sealing ring passes the vent hole. Then, the structure of the sealing ring tightening on the inner circumferential wall of the valve body cuts off the connection between the vent hole and the pressure chamber. This structure discharges gas before the pressure chamber is pressurized, improving the timeliness of subsequent braking response and ensuring the compactness of the brake valve structure.

[0009] In the aforementioned pressure-boosting structure of the brake valve, the oil inlet includes a guide section communicating with the valve body cavity and an inlet section extending to the outer peripheral wall of the valve body. The diameter of the inlet section is larger than the diameter of the guide section, and a stepped surface is formed at the connection. The vent is opened on the stepped surface, and the distance between the vent and the guide section along the valve body axial direction is greater than the thickness of the sealing ring along the valve body axial direction. By setting the diameter of the oil inlet, the oil inlet stability is improved. By opening the vent on the stepped surface, the opening accuracy of the vent is improved, and the opening length of the vent is shortened, increasing the speed at which gas and / or oil pass through the vent. By setting the distance between the vent and the guide section, the vent is prevented from being blocked by the sealing ring, ensuring the vent of the vent in the initial stage of the pressure chamber and improving the responsiveness of subsequent braking.

[0010] In the aforementioned pressure-boosting structure of the brake valve, the length of the inlet section is greater than the length of the drain section. The vent hole includes a venting section communicating with the valve body cavity and a flared section communicating with the inlet section, the diameter of which is greater than the diameter of the venting section. By making the length of the inlet section greater than the length of the drain section, the oil inlet velocity is increased. The structural design of the vent hole reduces oil outflow during venting, increases venting capacity, and thereby further improves the responsiveness of subsequent braking.

[0011] In the aforementioned pressure-boosting structure of the brake valve, both the venting section and the flared section are circular holes. The exhaust port also includes a conical connecting section, the larger end of which is connected to the flared section, and the smaller end of which is connected to the venting section. The connecting section guides the flow of gas and / or oil through the exhaust port, helping to increase the exhaust speed and thus improve the responsiveness of subsequent braking.

[0012] In the aforementioned pressure-boosting structure of the brake valve, the piston assembly has an annular groove, and the sealing ring has a D-shaped longitudinal section. The sealing ring is located within the annular groove, and the thickness of the sealing ring along the valve body axial direction is less than the groove width of the annular groove along the valve body axial direction. There is a gap between the inner ring of the sealing ring and the bottom of the annular groove. The D-shaped longitudinal section of the sealing ring increases the stroke required for the sealing ring to pass over the exhaust port without shortening the sealing ring thickness, thereby increasing the exhaust time and ensuring sufficient exhaust in the initial stage of pressure chamber formation. The sealing ring thickness being less than the groove width of the annular groove creates a misalignment between the piston assembly and the sealing ring, allowing an oil passage for oil supply to be formed between the piston assembly and the piston in the initial state. The movement of the piston assembly cuts off the oil passage, forming a pressure chamber and ensuring timely braking response.

[0013] In the aforementioned pressure-boosting structure of the brake valve, the piston assembly includes a main piston, a follower piston, and an auxiliary piston arranged sequentially along the axial direction of the valve body. The auxiliary piston divides the inner cavity of the valve body into a front chamber and a rear chamber. The follower piston is located in the front chamber and abuts against the main piston. Both the front and rear chambers are provided with a pair of the aforementioned oil inlet, brake oil outlet, and vent. This structure allows the valve body to form two pressure chambers during braking. Even if one pressure chamber fails, the other pressure chamber can still ensure braking effectiveness, improving braking stability. Furthermore, compared to setting a single pressure chamber, the two pressure chambers are smaller, the oil inlets of the front and rear chambers are independent, and the vent allows for venting from different positions in the valve body, increasing the total venting volume and further improving the responsiveness of the brakes.

[0014] In the aforementioned pressure-boosting structure of the brake valve, the auxiliary piston has an annular groove at its end away from the follower piston, and this end of the auxiliary piston has an annular retaining edge. A sealing ring is disposed within the annular groove. The pressure-boosting structure includes a cylindrical compression spring sleeved on the auxiliary piston. One end of the cylindrical compression spring abuts against the annular retaining edge, and the other end abuts against the side of the sealing ring facing the brake oil hole in the rear cavity. The cylindrical compression spring prevents the sealing ring from tilting during the movement of the auxiliary piston, ensuring the stability of pressure build-up in the rear cavity.

[0015] In the aforementioned pressurization structure of the brake valve, the auxiliary piston also has a limiting surface located at the oil inlet in the rear chamber, and the auxiliary piston further includes a conical guide section. The small end of the guide section is connected to the limiting surface, and a flow-limiting ring with an annular cross-section is fitted over the guide section. The flow-limiting ring is clearance-fitted with the valve body and is slidably connected between the limiting surface and the corresponding sealing ring. An annular guide groove is formed on the inner side of the flow-limiting ring. In the initial state, the flow-limiting ring abuts against the limiting surface under the action of gravity. When oil enters through the oil inlet, the flow-limiting ring abuts against the sealing ring under the action of the oil. The guide groove accelerates the flow of oil through the guide section. When the auxiliary piston abuts against the side of the sealing ring, blocking the connection between the oil inlet and the brake oil hole, the flow-limiting ring reduces the flow diameter, reduces the impact of the oil on the sealing ring, and reduces the size of the opening that the sealing ring needs to block, thus ensuring braking stability.

[0016] In the aforementioned pressure-boosting structure of the brake valve, the main piston has an annular groove at one end abutting against the follower piston. A sealing ring is located within this annular groove. A conical compression spring is fitted onto the main piston, situated within the annular groove. The small end of the conical compression spring abuts against the groove wall of the annular groove, while the large end abuts against the side of the sealing ring facing the brake oil hole in the front chamber. The conical compression spring prevents the sealing ring from tilting during the movement of the main piston, reducing the axial space occupied. Furthermore, by abutting the large end against the sealing ring, the contact area between the conical compression spring and the sealing ring is increased, improving the structural compactness of the brake valve.

[0017] In the aforementioned pressure-boosting structure of the brake valve, the pressure-boosting structure also includes a second compression spring located in the front chamber. The two ends of the second compression spring act on the follower piston and the auxiliary piston, respectively. The braking structure also includes a third compression spring located in the rear chamber. The two ends of the third compression spring act on the auxiliary piston and the rear chamber wall, respectively. The elastic force of the third compression spring is greater than that of the second compression spring. This structure, by setting the elastic forces of the second and third compression springs, allows the front chamber to build up pressure before the rear chamber. That is, the rear axle pressure chamber can output braking pressure to the corresponding brake oil hole before the front axle pressure chamber. This connects the rear axle pressure chamber to the rear wheel brake of the wheeled vehicle, and the front axle pressure chamber to the front wheel brake of the wheeled vehicle, so that the rear wheel brakes of the vehicle brake before the front wheel brakes, thereby improving braking stability.

[0018] Compared with the prior art, the pressure boosting structure of the brake valve provided by the present invention has the following advantages:

[0019] 1. Based on the flow path of the oil from the inlet to the brake oil port and the movement trajectory of the piston assembly, an exhaust port with a smaller diameter than the inlet is opened on the valve body and positioned between the inlet and the brake oil port. Utilizing the principle of gas flowing from high pressure to low pressure, the gas in the pressure chamber is discharged in the initial stage of oil entry, minimizing the participation of gas in the subsequent pressure chamber pressure build-up. This structure improves the timeliness of braking response and enhances structural compactness.

[0020] 2. An auxiliary piston is used to divide the inner cavity of the valve body into a front cavity and a rear cavity, so that two pressure chambers can be formed along the valve body axis during braking. This structure reduces the exhaust pressure of a single pressure chamber. The oil inlet, oil outlet and exhaust of the two pressure chambers are independent. The exhaust hole is used to exhaust the gas at different positions of the valve body, which increases the total amount of exhaust per unit time and further improves the timeliness of braking response. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of the brake valve in its initial state.

[0022] Figure 2 yes Figure 1 A magnified view of a portion of the image.

[0023] Figure 3 yes Figure 2 Enlarged views of points A and B in the middle.

[0024] Figure 4 This is a partial sectional view of the brake valve in braking state one.

[0025] Figure 5 yes Figure 4 A magnified view of a section at point C.

[0026] Figure 6This is a partial sectional view of the brake valve in braking state two.

[0027] Figure 7 yes Figure 6 Enlarged views of points D and E in the middle.

[0028] Figure 8 This is a partial sectional view of the brake valve in braking state three.

[0029] Figure 9 This is a partial sectional view of the brake valve in its reset state.

[0030] Figure 10 This is a 3D diagram of the auxiliary piston.

[0031] In the diagram, 1. Valve body; 11. Inner cavity; 111. Front cavity; 112. Rear cavity; 12. Oil inlet; 121. Drainage section; 122. Inlet section; 123. Stepped surface; 13. Brake oil hole; 14. Exhaust hole; 141. Vent section; 142. Flaring section; 143. Connecting section; 2. Piston assembly; 21. Annular groove; 22. Main piston; 23. Follower piston; 24. Auxiliary piston; 241. Annular retaining edge; 242. Limiting surface; 243. Guide section; 3. Sealing ring; 5. Cylindrical compression spring; 6. Flow limiting ring; 61. Guide groove; 7. Conical compression spring; 8. Compression spring two; 9. Compression spring three. Detailed Implementation

[0032] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0033] like Figure 1 As shown, the pressure boosting structure of this brake valve includes a valve body 1. The inner wall of the valve body 1 has at least one pair of oil inlet holes 12 for oil inlet and brake fluid outlet holes 13 for brake fluid outlet. A piston assembly 2 is slidably connected inside the valve body 1. Figure 2 and Figure 3 As shown, an annular groove 21 is provided on the piston assembly 2. A sealing ring 3 is fitted inside the annular groove 21 on the piston assembly 2, and there is a gap between the sealing ring 3 and the piston assembly 2 for oil to pass through. The longitudinal section of the sealing ring 3 is D-shaped. The sealing ring 3 is interference-fitted with the valve body 1. The thickness of the sealing ring 3 along the axial direction of the valve body 1 is less than the groove width of the annular groove 21 along the axial direction of the valve body 1. There is a gap between the inner ring of the sealing ring 3 and the bottom of the annular groove 21. Figures 2-8 As shown, when the piston assembly 2 moves toward the brake oil hole 13 and approaches the exhaust hole 14, the piston assembly 2 can come into contact with the sealing ring 3 to block the connection between the oil inlet hole 12 and the brake oil hole 13.

[0034] like Figure 2 , Figure 4 , Figure 6 , Figure 8 and Figure 9 As shown, the piston assembly 2 includes a main piston 22, a follower piston 23, and an auxiliary piston 24 arranged sequentially along the axial direction of the valve body 1. The auxiliary piston 24 divides the inner cavity 11 of the valve body 1 into a front cavity 111 and a rear cavity 112. The pressurization structure also includes a compression spring 28 located in the front cavity 111. The follower piston 23 is located in the front cavity 111 and abuts against the main piston 22 under the elastic force of the compression spring 28. The other end of the compression spring 28 acts on the auxiliary piston 24. The braking structure also includes a compression spring 39 located in the rear cavity 112. The two ends of the compression spring 39 act on the auxiliary piston 24 and the cavity wall of the rear cavity 112, respectively. The elastic force of the compression spring 39 is greater than the elastic force of the compression spring 28.

[0035] like Figure 2 , Figure 4 , Figure 6 , Figure 8 and Figure 9 As shown, both the front cavity 111 and the rear cavity 112 have a pair of oil inlet holes 12, brake oil holes 13, and vent holes 14 on their cavity walls, as described above. Figure 3 , Figure 5 , Figure 7 As shown, the booster structure includes an exhaust port 14 formed on the inner wall of the valve body 1. The outer end of the exhaust port 14 communicates with the oil inlet port 12. The diameter of the exhaust port 14 is smaller than the diameter of the oil inlet port 12. The exhaust port 14 is located between the oil inlet port 12 and the brake oil port 13. The sealing ring 3 is located axially between the oil inlet port 12 and the exhaust port 14. The oil inlet port 12 includes a guide section 121 communicating with the inner cavity 11 of the valve body 1 and an inlet section 122 extending to the outer peripheral wall of the valve body 1. The diameter of the inlet section 122 is larger than the diameter of the guide section 121, and a stepped surface 123 is formed at the connection. The exhaust port 14 is formed on the stepped surface 123. The distance between the exhaust port 14 and the flow section 121 along the axial direction of the valve body 1 is greater than the thickness of the sealing ring 3 along the axial direction of the valve body 1. The length of the inlet section 122 is greater than the length of the flow section 121. The exhaust port 14 includes a venting section 141 communicating with the inner cavity 11 of the valve body 1 and a flared section 142 communicating with the inlet section 122. The diameter of the flared section 142 is greater than the diameter of the venting section 141. Both the venting section 141 and the flared section 142 are round holes. The exhaust port 14 also includes a connecting section 143 in the shape of a conical hole. The large end of the connecting section 143 is connected to the flared section 142, and the small end of the connecting section 143 is connected to the venting section 141.

[0036] The auxiliary piston 24 has an annular groove 21 at the end away from the follower piston 23, and this end of the auxiliary piston 24 has an annular retaining edge 241. The sealing ring 3 is provided in the annular groove 21. When the auxiliary piston 24 moves towards the brake oil hole 13 in the rear cavity 112 and approaches the exhaust hole 14, the piston assembly 2 can abut against the sealing ring 3 to block the communication between the oil inlet hole 12 and the brake oil hole 13. The booster structure includes a cylindrical compression spring 5 sleeved on the auxiliary piston 24. One end of the cylindrical compression spring 5 abuts against the annular retaining edge 241, and the other end abuts against the sealing ring 3 on the other side facing the brake oil hole in the rear cavity 112. Figure 2 and Figure 10 As shown, the auxiliary piston 24 also has a limiting surface 242 located at the oil inlet 12 of the rear cavity 112, and the auxiliary piston 24 also includes a conical guide section 243. The small end of the guide section 243 is connected to the limiting surface 242, and the guide section 243 is sleeved with a flow limiting ring 6 with an annular cross-section. The flow limiting ring 6 is clearance-fitted with the valve body 1, and the flow limiting ring 6 is slidably connected between the limiting surface 242 and the corresponding sealing ring 3. The inner side of the flow limiting ring 6 is provided with an annular guide groove 61.

[0037] like Figure 2 , Figure 4 , Figure 6 , Figure 8 and Figure 9 As shown, the main piston 22 has an annular groove 21 at one end that abuts against the follower piston 23. The sealing ring 3 is provided in the annular groove 21. When the main piston 22 moves toward the brake oil hole 13 in the front cavity 111 and approaches the exhaust hole 14, the piston assembly 2 can abut against the sealing ring 3 to block the communication between the oil inlet hole 12 and the brake oil hole 13. A conical compression spring 7 is sleeved on the main piston 22 and located in the annular groove 21. The small end of the conical compression spring 7 abuts against the groove wall of the annular groove 21, and the large end abuts against the other side of the sealing ring 3 facing the brake oil hole in the front cavity 111.

[0038] When the driver depresses the brake pedal, the brake valve enters the braking state. The main piston 22, under hydraulic pressure, overcomes the spring force of the compression spring 28 and drives the follower piston 23 to move synchronously. In the initial braking condition after the initial installation of the braking system or the first braking operation after major maintenance, the inner cavity 11 of the valve body 1 initially contains no hydraulic fluid. When the main piston 22 moves, hydraulic fluid enters through the inlet port 12 of the front cavity 111. When the pressure in the inner cavity 11 of the valve body 1 exceeds the pressure of the inlet port, exhaust is released through the vent port 14. When the follower piston 23 abuts against the sealing ring 3 of the front cavity 111, but the sealing ring 3 does not pass the vent port 14, the connection between the inlet port 12 and the brake fluid port 13 of the front cavity 111 is cut off, and a pressure chamber is formed in the front cavity 111 between the follower piston 23 and the auxiliary piston 24. The follower piston 23 drives the sealing ring 3 to continue moving, and the gas in the pressure chamber continues to be discharged from the vent port 14. Because the sealing ring 3 and the valve... The inner cavity 11 of body 1 is interference-fitted. When the follower piston 23 passes the exhaust port 14, the pressure chamber of the front cavity 111 is pressurized, and hydraulic oil is output from the corresponding brake oil port 13. As the follower piston 23 moves, the pressure in the pressure chamber continuously increases, overcoming the elastic force of the compression spring 39 to drive the auxiliary piston 24 to move. Oil enters through the oil inlet port 12 of the rear cavity 112, and exhausts through the exhaust port 14. When the auxiliary piston 24 abuts against the sealing ring 3 of the rear cavity 112, but the sealing ring 3 has not passed the exhaust port 14, the connection between the oil inlet port 12 and the brake oil port 13 of the rear cavity 112 is cut off. A pressure chamber is formed in the rear cavity 112 between the auxiliary piston 24 and the wall of the rear cavity 112. The auxiliary piston 24 drives the sealing ring 3 to continue to move, and the gas in the pressure chamber continues to be discharged from the exhaust port 14. When the auxiliary piston 24 passes the exhaust port 14, the pressure chamber of the rear cavity 112 is pressurized, and hydraulic oil is output from the corresponding brake oil port.

[0039] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0040] Although this document frequently uses terms such as valve body 1, inner cavity 11, front cavity 111, rear cavity 112, oil inlet 12, guide section 121, inlet section 122, stepped surface 123, brake oil hole 13, exhaust hole 14, venting section 141, flared section 142, connecting section 143, piston assembly 2, annular groove 21, main piston 22, follower piston 23, auxiliary piston 24, annular flange 241, limiting surface 242, guide section 243, sealing ring 3, cylindrical compression spring 5, flow limiting ring 6, guide groove 61, conical compression spring 7, compression spring two 8, compression spring three 9, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A pressure boosting structure for a brake valve, the brake valve comprising a valve body (1), wherein the inner wall of the valve body (1) is provided with at least one pair of oil inlet holes (12) for oil inlet and brake oil holes (13) for brake oil outlet, a piston assembly (2) is slidably connected inside the valve body (1), a sealing ring (3) is provided on the piston assembly (2) and tightened on the inner peripheral wall of the valve body (1), and there is a gap between the sealing ring (3) and the piston assembly (2) for oil to pass through, characterized in that, The booster structure includes an exhaust port (14) on the inner wall of the valve body (1). The outer end of the exhaust port (14) is connected to the oil inlet port (12). The diameter of the exhaust port (14) is smaller than that of the oil inlet port (12). The exhaust port (14) is located between the oil inlet port (12) and the brake oil port (13). The sealing ring (3) is located between the oil inlet port (12) and the exhaust port (14) along the axial direction of the valve body (1). When the piston assembly (2) moves toward the brake oil port (13) and approaches the exhaust port (14), the piston assembly (2) can abut against the sealing ring (3) to block the connection between the oil inlet port (12) and the brake oil port (13).

2. The pressure boosting structure of the brake valve according to claim 1, characterized in that, The oil inlet (12) includes a flow section (121) communicating with the inner cavity (11) of the valve body (1) and an inlet section (122) extending to the outer peripheral wall of the valve body (1). The diameter of the inlet section (122) is larger than the diameter of the flow section (121) and a stepped surface (123) is formed at the connection. The vent (14) is opened on the stepped surface (123), and the distance between the vent (14) and the flow section (121) along the axial direction of the valve body (1) is greater than the thickness of the sealing ring (3) along the axial direction of the valve body (1).

3. The pressure boosting structure of the brake valve according to claim 2, characterized in that, The length of the inlet section (122) is greater than the length of the drainage section (121). The exhaust port (14) includes a ventilation section (141) communicating with the inner cavity (11) of the valve body (1) and a flared section (142) communicating with the inlet section (122). The diameter of the flared section (142) is greater than the diameter of the ventilation section (141).

4. The pressure boosting structure of the brake valve according to claim 3, characterized in that, Both the ventilation section (141) and the flared section (142) are round holes. The exhaust hole (14) also includes a conical connecting section (143). The large end of the connecting section (143) is connected to the flared section (142), and the small end of the connecting section (143) is connected to the ventilation section (141).

5. The pressure boosting structure of the brake valve according to any one of claims 1-4, characterized in that, The piston assembly (2) has an annular groove (21) and the sealing ring (3) has a D-shaped longitudinal section. The sealing ring (3) is located in the annular groove (21). The thickness of the sealing ring (3) along the axial direction of the valve body (1) is less than the groove width of the annular groove (21) along the axial direction of the valve body (1). There is a gap between the inner ring of the sealing ring (3) and the bottom of the annular groove (21).

6. The pressure boosting structure of the brake valve according to claim 5, characterized in that, The piston assembly (2) includes a main piston (22), a follower piston (23) and an auxiliary piston (24) arranged sequentially along the axial direction of the valve body (1). The auxiliary piston (24) divides the inner cavity (11) of the valve body (1) into a front cavity (111) and a rear cavity (112). The follower piston (23) is located in the front cavity (111) and abuts against the main piston (22). The front cavity (111) and the rear cavity (112) are each provided with a pair of the above-mentioned oil inlet (12), brake oil hole (13) and exhaust hole (14).

7. The pressure boosting structure of the brake valve according to claim 6, characterized in that, The auxiliary piston (24) has an annular groove (21) at one end away from the follower piston (23), and the auxiliary piston (24) has an annular retaining edge (241) at this end. The annular groove (21) is provided with the sealing ring (3). The pressurization structure includes a cylindrical compression spring (5) sleeved on the auxiliary piston (24). One end of the cylindrical compression spring (5) abuts against the annular retaining edge (241), and the other end abuts against the side of the sealing ring (3) facing the brake oil hole (13) of the rear cavity (112).

8. The pressure boosting structure of the brake valve according to claim 7, characterized in that, The auxiliary piston (24) also has a limiting surface (242) located at the oil inlet (12) of the rear cavity (112), and the auxiliary piston (24) also includes a conical guide section (243). The small end of the guide section (243) is connected to the limiting surface (242), and the guide section (243) is covered with a flow limiting ring (6) with an annular cross-section. The flow limiting ring (6) is clearance-fitted with the valve body (1), and the flow limiting ring (6) is slidably connected between the limiting surface (242) and the corresponding sealing ring (3). The inner side of the flow limiting ring (6) is provided with an annular guide groove (61).

9. The pressure boosting structure of the brake valve according to claim 6, characterized in that, The main piston (22) has an annular groove (21) at one end that abuts against the follower piston (23). The annular groove (21) is provided with the sealing ring (3). A conical compression spring (7) is sleeved on the main piston (22) and located in the annular groove (21). The small end of the conical compression spring (7) abuts against the groove wall of the annular groove (21), and the large end abuts against the side of the sealing ring (3) facing the brake oil hole (13) of the front cavity (111).

10. The pressure boosting structure of the brake valve according to claim 6, characterized in that, The boosting structure also includes a second compression spring (8) located in the front chamber (111), the two ends of which act on the follower piston (23) and the auxiliary piston (24) respectively. The braking structure also includes a third compression spring (9) located in the rear chamber (112), the two ends of which act on the auxiliary piston (24) and the cavity wall of the rear chamber (112) respectively. The elastic force of the third compression spring (9) is greater than that of the second compression spring (8).

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