Brake structure of brake valve

Abstract

The invention provides a brake structure of a brake valve, and belongs to the technical field of brake valves. The problem that an existing brake is poor in stability is solved. According to the brake structure of the brake valve, a main piston is slidably connected into a lower valve body, a follow-up piston is slidably connected into an upper valve body, the follow-up piston abuts against the main piston, the brake structure comprises an auxiliary piston, the auxiliary piston is slidably connected into the upper valve body, an inner cavity of the upper valve body is divided into a front cavity and a rear cavity by the auxiliary piston, and the follow-up piston is located in the front cavity. A pair of oil inlets and a pair of brake oil ports are formed in the cavity wall of the front cavity and the cavity wall of the rear cavity respectively, and when the follow-up piston moves towards the auxiliary piston, a rear axle pressure cavity used for generating brake pressure can be formed between one end of the auxiliary piston and the follow-up piston. When the auxiliary piston moves in the direction away from the follow-up piston, a front axle pressure cavity used for generating brake pressure can be formed between the other end of the auxiliary piston and the inner cavity wall of the upper valve body. The brake structure of the brake valve has the advantage of improving the brake stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of brake valves and relates to a brake structure of a brake valve. BACKGROUND

[0002] The brake system of a wheeled engineering vehicle usually takes a full-hydraulic brake valve as a core control element. The brake valve comprises an inlet and a working oil port. In an initial state, the inlet is communicated with the working oil port. When a driver steps on a brake pedal, a driving piston moves forward to close the inlet, and a pressure cavity is formed in the valve body. The piston continues to move forward to extrude the oil in the pressure cavity, so that the oil pressure is increased. The high-pressure oil is output to a wheel brake through the working oil port to generate a braking force.

[0003] During the braking process of the brake valve, the sealing of the pressure cavity needs to be ensured, and the sealing of the pressure cavity mainly depends on a sealing ring on the piston. If the sealing ring fails due to long-term wear, aging or accidental damage, the pressure cavity will not be able to maintain a sealed state. At this time, the movement of the piston will cause the high-pressure oil to leak from the sealing failure position, so that the pressure cavity cannot be pressurized, and then the brake pedal is empty and the braking force is lost. To solve the problem that the brake fails due to the sealing failure of the pressure cavity, those skilled in the art are prone to starting from the sealing structure, such as setting a double-sealing structure or selecting a more wear-resistant material to manufacture the sealing ring. When the first sealing ring fails, the second sealing ring can still seal the pressure cavity. SUMMARY

[0004] The application aims to solve the above problems in the prior art and provides a brake structure of a brake valve to improve the poor braking stability.

[0005] The application can be implemented by the following technical scheme.

[0006] The application provides a brake structure of a brake valve. The brake valve comprises a lower valve body and an upper valve body. A main piston is slidably connected in the lower valve body. A follow-up piston is slidably connected in the upper valve body and abuts against the main piston. The brake structure comprises an auxiliary piston. The auxiliary piston is slidably connected in the upper valve body, and the auxiliary piston divides an inner cavity of the upper valve body into a front cavity and a rear cavity. The follow-up piston is located in the front cavity. A pair of inlet ports and brake oil ports are formed in the cavity walls of the front cavity and the rear cavity. When the follow-up piston moves towards the auxiliary piston, a rear axle pressure cavity for generating a braking pressure is formed between one end of the auxiliary piston and the follow-up piston. The rear axle pressure cavity is only communicated with the brake oil port of the front cavity. When the auxiliary piston moves away from the follow-up piston, a front axle pressure cavity for generating a braking pressure is formed between the other end of the auxiliary piston and the inner cavity wall of the upper valve body. The front axle pressure cavity is only communicated with the brake oil port of the rear cavity.

[0007] The application adds an auxiliary piston in the upper valve body, so that the inner cavity of the upper valve body is divided into a front cavity and a rear cavity, a pair of oil inlets and brake oil ports are arranged on the cavity walls of the front cavity and the rear cavity, the rear axle pressure cavity which only communicates with the brake oil port can be formed in the front cavity, the oil in the rear axle pressure cavity is pressurized through the movement of the follow-up piston, and the pressurized oil is output to the brake from the brake oil port of the front cavity, the front axle pressure cavity which only communicates with the brake oil port can be formed in the rear cavity, the oil in the front axle pressure cavity is pressurized through the movement of the auxiliary piston, and the pressurized oil is output to the brake from the brake oil port of the rear cavity, that is, two pressure cavities can be formed in the brake valve of the application, in actual application, the brake oil port of the front cavity of the application is communicated with the rear wheel brake of the wheeled vehicle, and the brake oil port of the rear cavity is communicated with the front wheel brake of the wheeled vehicle, so that the brake valve of the application can form two independent brake circuits, even if one brake circuit fails due to pressure cavity leakage, the other brake circuit can still ensure the effectiveness of braking, thereby improving the braking stability.

[0008] In the brake structure of the brake valve, the inner cavity wall of the upper valve body has an outwardly protruding and annular shoulder, one side of the shoulder has a first limiting surface facing the auxiliary piston, one end of the auxiliary piston can abut against the first limiting surface, and the end is sleeved with a first sealing ring abutting against the inner cavity wall of the upper valve body, and the first sealing ring divides the inner cavity of the upper valve body to form the front cavity and the rear cavity. When the brake valve is in the initial state, the auxiliary piston abuts against the first limiting surface, so that the initial position of the auxiliary piston in the valve body is determined, and the first sealing ring moves with the auxiliary piston, so that the front cavity and the rear cavity change. This structure maximizes the use of the inner cavity of the upper valve body, ensures the volume of the rear axle pressure cavity and the front axle pressure cavity, and further ensures the braking stability.

[0009] In the brake structure of the brake valve, the outer peripheral wall of the auxiliary piston is provided with a first annular groove, the first sealing ring is located in the first annular groove, the longitudinal section of the first sealing ring is U-shaped, and the opening of the first sealing ring faces the direction of the follow-up piston, and the auxiliary piston and the upper valve body have a communication structure communicating the front cavity and the first annular groove. This structure introduces the oil in the front cavity into the opening of the first sealing ring through the communication structure, so that the first sealing ring is stretched in the transverse direction, ensuring the sealing between the front cavity and the rear cavity, and further ensuring the braking stability.

[0010] In the braking structure of the aforementioned brake valve, the connecting structure includes a notch formed on the protruding surface of the shoulder, the notch extending to the first limiting surface, the brake oil port of the front cavity communicating with the notch, a drainage gap between one end of the auxiliary piston and the cavity wall of the upper valve body, the drainage gap communicating with the notch and the first annular groove, the groove width of the first annular groove along the axial direction of the auxiliary piston being greater than the thickness of the first sealing ring along the axial direction of the auxiliary piston, when the auxiliary piston moves away from the follower piston, the groove wall of the first annular groove can completely block the opening of the first sealing ring. The width of the first annular groove along the axial direction of the auxiliary piston is greater than the thickness of the first sealing ring along the axial direction of the auxiliary piston. When the auxiliary piston is in the initial state, there is a gap between the groove wall of the first annular groove and the side of the first sealing ring with an opening. The drainage gap guides the oil flowing through the notch in the front cavity to enter the opening of the first sealing ring, and the first sealing ring opens. When the auxiliary piston moves away from the follower piston, the auxiliary piston moves relative to the first sealing ring until the groove wall of the first annular groove abuts against the side of the first sealing ring with an opening, so that the opening of the first sealing ring is completely blocked. The auxiliary piston drives the first sealing ring to move. During the movement of the auxiliary piston, the U-shaped cavity of the first sealing ring is filled with oil, so that the first sealing ring is in an open state, ensuring the sealing between the front cavity and the rear cavity, thereby improving braking stability.

[0011] In the braking structure of the aforementioned brake valve, a second annular sealing ring is provided on the wall of the front chamber. The second sealing ring is located on the other side of the shoulder. When the outer peripheral wall of the follower piston abuts against the inner ring of the second sealing ring, the aforementioned rear axle pressure chamber is formed between one end of the auxiliary piston and the follower piston. This structure makes reasonable use of the internal cavity space of the upper valve body.

[0012] In the braking structure of the aforementioned brake valve, a compression spring and a third sealing ring are fitted onto the end of the auxiliary piston away from the follower piston. The longitudinal section of the third sealing ring is D-shaped. The outer ring of the third sealing ring abuts against the cavity wall of the rear chamber, and there is a gap between the inner ring and the auxiliary piston. One end of the compression spring acts on the auxiliary piston, and the other end acts on one side of the third sealing ring. The auxiliary piston also has a second limiting surface. There is an oil-blocking gap between the second limiting surface and the other side of the third sealing ring, which communicates with the oil inlet of the rear chamber. When the auxiliary piston moves away from the follower piston, the second limiting surface abuts against the other side of the third sealing ring, so that the end of the auxiliary piston and the inner cavity wall of the upper valve body form the aforementioned front axle pressure chamber. This structure combines the movement trajectory of the auxiliary piston with the structural features of the third sealing ring. Because the outer ring of the third sealing ring abuts against the cavity wall of the rear chamber, when the second limiting surface does not abut against the side of the third sealing ring, the auxiliary piston moves relative to the third sealing ring, thereby eliminating the oil blocking gap. At the same time, the third sealing ring abuts against the second limiting surface under the elastic force of the compression spring, ensuring the stability of the contact between the second limiting surface and the third sealing ring, that is, ensuring the sealing of the front axle pressure chamber, thereby ensuring braking stability.

[0013] In the braking structure of the aforementioned brake valve, the auxiliary piston has a cylindrical contraction section and a conical guide section. The third sealing ring is fitted onto the contraction section. The large end face of the guide section is the aforementioned second limiting surface. The auxiliary piston also has a third limiting surface located at the oil inlet of the rear chamber. A flow-limiting element is fitted over the guide section. The flow-limiting element is slidably connected between the third sealing ring and the third limiting surface. An oil control gap is formed between the flow-limiting element and the guide section, connecting the oil inlet of the rear chamber and the oil blocking gap. When oil enters the oil inlet of the rear chamber, the flow-limiting element slides towards the third sealing ring under the action of the oil, increasing the oil inlet diameter. When the flow-limiting element moves back under the action of the third sealing ring, it limits the flow of oil flowing towards the oil blocking gap, minimizing the impact of the oil on the third sealing ring and reducing the size of the opening that the third sealing ring needs to seal, further improving the sealing performance of the front axle pressure chamber, thereby ensuring braking stability.

[0014] In the braking structure of the aforementioned brake valve, the auxiliary piston also has a sliding section that abuts against the cavity wall of the rear chamber. The sliding section is connected to the small end of the guide section to form the aforementioned third limiting surface. The auxiliary piston has a flow-guiding hole that extends radially from the sliding section to the guide section. The flow-guiding hole connects the oil inlet of the rear chamber and the oil control gap. The cross-section of the flow-limiting element is annular. The outer end of the flow-limiting element is clearance-fitted with the upper valve body, and the inner ring of the flow-limiting element has a second annular groove. The outer end of the flow restrictor is fitted with the upper valve body with a clearance, allowing the flow restrictor to move relative to the auxiliary piston. When oil enters the rear chamber through the inlet, the flow restrictor, with the help of the flow restriction gap, moves relative to the auxiliary piston towards the third sealing ring along with the oil. The second annular groove moves to the large end of the guide section. At this time, the second annular groove increases the cross-sectional area at the connection between the oil control gap and the oil blocking gap, accelerating the oil intake speed. Furthermore, under the elastic force of the compression spring, the third sealing ring drives the flow restrictor to move back. The flow restrictor, under the action of the oil, abuts against the third sealing ring, achieving bidirectional contact. At this time, the cross-sectional area at the connection between the oil control gap and the oil blocking gap decreases. This structure improves the sealing performance of the rear axle pressure chamber, thereby further ensuring braking stability.

[0015] In the braking structure of the aforementioned brake valve, the auxiliary piston also has an extension section connected to the sliding section. An oil storage gap exists between the extension section and the rear chamber wall. A pressure relief groove is provided on the sliding section, connecting the oil storage gap and the drainage hole. Because the auxiliary piston is slidably connected to the upper valve body, the extension section reduces the contact area between the auxiliary piston and the lower valve body. Oil retained in the oil storage gap can be discharged through the pressure relief groove. This structure minimizes the movement resistance of the auxiliary piston, ensuring smooth movement and thus improving the braking stability of the brake valve.

[0016] In the aforementioned braking structure of the brake valve, the braking structure further includes a second compression spring located in the front chamber, with its two ends acting on the follower piston and the auxiliary piston, respectively. The braking structure also includes a third compression spring located in the rear chamber, with its two ends acting 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 adjusting the elastic forces of the second and third compression springs, ensures that the front chamber builds pressure before the rear chamber. That is, the rear axle pressure chamber can output braking pressure to the corresponding brake port before the front axle pressure chamber. This connects the rear axle pressure chamber to the rear wheel brakes of the wheeled vehicle, and the front axle pressure chamber to the front wheel brakes of the wheeled vehicle, ensuring that the rear wheel brakes precede the front wheel brakes, thereby improving braking stability.

[0017] Compared with the prior art, the braking structure of the brake valve provided by the present invention has the following advantages:

[0018] 1. The auxiliary piston divides the inner cavity of the upper valve body into a front cavity and a rear cavity, connecting the brake oil port of the front cavity to the rear wheel brake of the wheeled vehicle and the brake oil port of the rear cavity to the front wheel brake of the wheeled vehicle, so that the brake valve of this application forms two independent braking circuits. Even if one of the braking circuits fails, braking can still be guaranteed, thereby improving braking stability.

[0019] 2. In this application, the longitudinal section of the first sealing ring separating the front cavity and the rear cavity is U-shaped. By utilizing its shape characteristics, the oil in the front cavity is introduced into the U-shaped groove of the first sealing ring through the connecting structure. The first sealing ring is stretched laterally to ensure the sealing between the front cavity and the rear cavity, thereby ensuring braking stability.

[0020] 3. The spring force of compression spring three is greater than that of compression spring two, connecting 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 car brakes before the front wheel brakes, thereby improving braking stability. 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 A magnified view of a portion of point A in the middle.

[0024] Figure 4 This is a 3D diagram of the auxiliary piston.

[0025] Figure 5 This is a partial sectional view of the brake valve in braking state one.

[0026] Figure 6 yes Figure 5 A magnified view of a section at point B in the middle.

[0027] Figure 7 This is a partial sectional view of the brake valve in braking state two.

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

[0029] In the diagram, 1. Lower valve body; 2. Upper valve body; 21. Front chamber; 211. Rear axle pressure chamber; 22. Rear chamber; 221. Front axle pressure chamber; 23. Oil inlet; 24. Brake oil port; 25. Shoulder; 251. First limiting surface; 252. Notch; 3. Main piston; 4. Follower piston; 5. Auxiliary piston; 51. First annular groove; 52. Second limiting surface; 53. Contraction section; 54. Guide section; 55. Third limiting surface; 56, sliding section; 561, pressure relief groove; 57, extension section; 58, drainage hole; 6, first sealing ring; 7, drainage gap; 8, second sealing ring; 9, compression spring one; 10, third sealing ring; 11, oil blocking gap; 12, flow limiting element; 121, second annular groove; 13, oil control gap; 14, oil storage gap; 15, compression spring two; 16, compression spring three; 17, oil replenishment chamber. Detailed Implementation

[0030] 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.

[0031] like Figure 1 and Figure 2 As shown, the braking structure of this brake valve includes a lower valve body 1 and an upper valve body 2. A main piston 3 is slidably connected inside the lower valve body 1, and a follower piston 4 is slidably connected inside the upper valve body 2. The follower piston 4 abuts against the main piston 3. The braking structure includes an auxiliary piston 5, which is slidably connected inside the upper valve body 2. The inner wall of the upper valve body 2 has an outwardly protruding, annular shoulder 25. One side of the shoulder 25 has a first limiting surface 251 facing the auxiliary piston 5. When the brake valve is in the initial position, one end of the auxiliary piston 5 abuts against the first limiting surface 251, and this end is fitted with a first sealing ring 6 that abuts against the inner wall of the upper valve body 2. The first sealing ring 6 separates the inner cavity of the upper valve body 2 to form a front cavity 21 and a rear cavity 22. The follower piston 4 is located in the front cavity 21. Both the front cavity 21 and the rear cavity 22 have a pair of oil inlets 23 for oil inlet and a brake oil port 24 for high-pressure oil outlet. Figure 5 and Figure 7 As shown, when the follower piston 4 moves toward the auxiliary piston 5, a rear axle pressure chamber 211 for generating braking pressure can be formed in the front chamber 21, and the rear axle pressure chamber 211 is only connected to the corresponding brake oil port 24; when the auxiliary piston 5 moves away from the follower piston 4, a front axle pressure chamber 221 for generating braking pressure can be formed in the rear chamber 22, and the front axle pressure chamber 221 is only connected to the corresponding brake oil port 24.

[0032] like Figure 2As shown, the outer peripheral wall of the auxiliary piston 5 has a first annular groove 51, and the first sealing ring 6 is embedded in the first annular groove 51. The longitudinal section of the first sealing ring 6 is U-shaped, and the opening of the first sealing ring 6 faces the direction of the follower piston 4. The auxiliary piston 5 and the upper valve body 2 have a communication structure connecting the front cavity 21 and the first annular groove 51. The communication structure includes a notch 252 opened on the protruding surface of the shoulder 25, which extends to the first limiting surface 251. The brake oil port 24 of the front cavity 21 communicates with the notch 252. One end of the auxiliary piston 5 has a drainage gap 7 between it and the cavity wall of the upper valve body 2. The drainage gap 7 connects the notch 252 and the first annular groove 51. The groove width of the first annular groove 51 along the axial direction of the auxiliary piston 5 is greater than the thickness of the first sealing ring 6 along the axial direction of the auxiliary piston 5. Figure 5 and Figure 7 As shown, when the auxiliary piston 5 moves away from the follower piston 4, the groove wall of the first annular groove 51 can completely block the opening of the first sealing ring 6.

[0033] The front cavity 21 has an annular second sealing ring 8 on its cavity wall. The second sealing ring 8 is located on the other side of the shoulder 25. When the outer peripheral wall of the follower piston 4 abuts against the inner ring of the second sealing ring 8, the aforementioned rear shaft pressure cavity 211 is formed between the first sealing ring 6 and the second sealing ring 8. Figure 3 and Figure 6 As shown, a compression spring 9 and a third sealing ring 10 are fitted on the end of the auxiliary piston 5 away from the follower piston 4. The longitudinal section of the third sealing ring 10 is D-shaped. The outer ring of the third sealing ring 10 abuts against the cavity wall of the rear cavity 22, and there is a gap between the inner ring of the third sealing ring 10 and the auxiliary piston 5. One end of the compression spring 9 acts on the auxiliary piston 5, and the other end acts on one side of the third sealing ring 10. The auxiliary piston 5 also has a second limiting surface 52. There is an oil-blocking gap 11 between the second limiting surface 52 and the other side of the third sealing ring 10, which communicates with the oil inlet 23 of the rear cavity 22. When the auxiliary piston 5 moves away from the follower piston 4, the second limiting surface 52 can abut against the other side of the third sealing ring 10, so that the end of the auxiliary piston 5 and the rear cavity 22 form the aforementioned front shaft pressure chamber 221.

[0034] like Figure 4 As shown, the auxiliary piston 5 has a cylindrical contraction section 53, a conical guide section 54, and a sliding section 56 that abuts against the cavity wall of the rear cavity 22, as... Figure 3 and Figure 6As shown, the third sealing ring 10 is fitted onto the contraction section 53. The large end face of the guide section 54 is the aforementioned second limiting surface 52. The sliding section 56 is connected to the small end of the guide section 54 to form the third limiting surface 55. The third limiting surface 55 is located at the oil inlet 23 of the rear cavity 22. The guide section 54 is fitted with a flow limiting member 12, which is slidably connected between the third sealing ring 10 and the third limiting surface 55. An oil control gap 13 is formed between the flow limiting member 12 and the guide section 54, connecting the oil inlet 23 of the rear cavity 22 and the oil blocking gap 11. The auxiliary piston 5 has a flow guide hole 58 extending radially from the sliding section 56 to the guide section 54. The flow guide hole 58 connects the oil inlet 23 of the rear cavity 22 and the oil control gap 13. The cross-section of the flow limiting member 12 is annular. The outer end of the flow limiting member 12 is clearance-fitted with the upper valve body 2, and the inner ring of the flow limiting member 12 has a second annular groove 121.

[0035] like Figures 2-4 As shown, the auxiliary piston 5 also has an extension section 57 connected to the sliding section 56. There is an oil storage gap 14 between the extension section 57 and the wall of the rear cavity 22. The sliding section 56 is provided with a pressure relief groove 561 that connects the oil storage gap 14 and the drainage hole 58. The braking structure also includes a compression spring 2 15 located in the front cavity 21. The two ends of the compression spring 2 15 act on the follower piston 4 and the auxiliary piston 5, respectively. The braking structure also includes a compression spring 3 16 located in the rear cavity 22. The two ends of the compression spring 3 16 act on the auxiliary piston 5 and the wall of the rear cavity 22, respectively. The elastic force of the compression spring 3 16 is greater than that of the compression spring 2 15.

[0036] like Figures 1-8As shown, the brake valve of this application is mainly used in engineering vehicles. The rear wheel brakes of engineering vehicles are all connected to the rear axle pressure chamber 211, and the front wheel brakes of engineering vehicles are all connected to the front axle pressure chamber 221. The working principle of this brake valve is as follows: When the driver presses the brake pedal, the lower valve body 1 builds pressure, driving the main piston 3 to move upward. The main piston 3 overcomes the elastic force of the compression spring 15 and drives the follower piston 4 to move synchronously. During the movement, the oil inlet 23 in the front chamber 21 is cut off. The follower piston 4 continues to move, so that the outer wall of the follower piston 4 abuts against the inner ring of the second sealing ring 8. The rear axle pressure chamber 211 is formed in the front chamber 21 between the first sealing ring 6 and the second sealing ring 8. The brake oil in the rear axle pressure chamber 211 is output through the brake oil port 24 of the front chamber 21. At this time, the flow restrictor 12 abuts against the third sealing ring 10 under the action of the oil inlet 23 of the rear chamber 22. The second annular groove 12 1. Increase the oil control gap 13 formed between the flow obstruction component and the flow guide component; the follower piston 4 continues to move, the oil replenishment chamber 17 replenishes the brake oil port 24 of the front chamber 21 with oil, the pressure of the rear axle pressure chamber 211 overcomes the elastic force of the compression spring 16, and drives the auxiliary piston 5 to move. The second limiting surface 52 abuts against the third sealing ring 10, and the third sealing ring 10 abuts against the second limiting surface 52 under the elastic force of the compression spring 9. At this time, the flow obstruction component abuts against the third limiting surface 55, cutting off the oil inlet 23 in the rear chamber 22, so that the end of the auxiliary piston 5 and the rear chamber 22 form the aforementioned front axle pressure chamber 221, and the brake oil in the front axle pressure chamber 221 is output through the brake oil port 24 of the rear chamber 22.

[0037] 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.

[0038] Although this article uses a lot of terms such as lower valve body 1, upper valve body 2, front chamber 21, rear axle pressure chamber 211, rear chamber 22, front axle pressure chamber 221, oil inlet 23, brake oil port 24, shoulder 25, first limiting surface 251, notch 252, main piston 3, follower piston 4, auxiliary piston 5, first annular groove 51, second limiting surface 52, contraction section 53, guide section 54, third limiting surface 55, sliding section 56, pressure relief groove 561, extension section 57, drainage hole 58, first sealing ring 6, drainage gap 7, second sealing ring 8, compression spring one 9, third sealing ring 10, oil blocking gap 11, flow limiting element 12, second annular groove 121, oil control gap 13, oil storage gap 14, compression spring two 15, compression spring three 16, and oil replenishment chamber 17, the possibility of using other terms cannot be ruled out. The use of these terms is merely for the convenience of describing and explaining the nature of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. A brake structure of a brake valve, the brake valve comprising a lower valve body (1) and an upper valve body (2), a main piston (3) being slidably connected in the lower valve body (1), a follower piston (4) being slidably connected in the upper valve body (2), the follower piston (4) abutting against the main piston (3), characterized in that, The brake structure comprises an auxiliary piston (5) which is slidingly connected in the upper valve body (2) and separates the inner cavity of the upper valve body (2) into a front cavity (21) and a rear cavity (22), the follow-up piston (4) is located in the front cavity (21), a pair of oil inlets (23) and brake oil ports (24) are formed on the cavity walls of the front cavity (21) and the rear cavity (22), when the follow-up piston (4) moves towards the auxiliary piston (5), a rear axle pressure cavity (211) for generating brake pressure is formed between one end of the auxiliary piston (5) and the follow-up piston (4), the rear axle pressure cavity (211) only communicates with the brake oil port (24) of the front cavity (21); when the auxiliary piston (5) moves away from the follow-up piston (4), a front axle pressure cavity (221) for generating brake pressure is formed between the other end of the auxiliary piston (5) and the inner cavity wall of the upper valve body (2), the front axle pressure cavity (221) only communicates with the brake oil port (24) of the rear cavity (22).

2. The brake structure of the brake valve according to claim 1, characterized by The inner cavity wall of the upper valve body (2) has an outwardly protruding and annular shoulder (25), one side of the shoulder (25) has a first limiting surface (251) facing the auxiliary piston (5), one end of the auxiliary piston (5) can abut against the first limiting surface (251), and a first sealing ring (6) abutting against the inner cavity wall of the upper valve body (2) is sleeved on the end, the first sealing ring (6) separates the inner cavity of the upper valve body (2) to form the above-mentioned front cavity (21) and rear cavity (22).

3. The brake structure of the brake valve according to claim 2, characterized by An annular first groove (51) is formed on the outer peripheral wall of the auxiliary piston (5), the first sealing ring (6) is located in the first annular groove (51), the longitudinal section of the first sealing ring (6) is U-shaped, and the opening of the first sealing ring (6) faces the direction of the follow-up piston (4), the auxiliary piston (5) and the upper valve body (2) have a communication structure which communicates the front cavity (21) and the first annular groove (51).

4. The brake structure of the brake valve according to claim 3, characterized by The communication structure comprises a notch (252) formed on the protruding surface of the shoulder (25), the notch (252) extends to the first limiting surface (251), the brake oil port (24) of the front cavity (21) communicates with the notch (252), the end of the auxiliary piston (5) and the cavity wall of the upper valve body (2) have a drainage gap (7), the drainage gap (7) communicates the notch (252) and the first annular groove (51), the groove width of the first annular groove (51) in the axial direction of the auxiliary piston (5) is greater than the thickness of the first sealing ring (6) in the axial direction of the auxiliary piston (5), when the auxiliary piston (5) moves away from the follow-up piston (4), the groove wall of the first annular groove (51) can completely block the opening of the first sealing ring (6).

5. The brake structure of the brake valve according to any one of claims 2 to 4, characterized in that, An annular second sealing ring (8) is arranged on the cavity wall of the front cavity (21), the second sealing ring (8) is located on the other side of the shoulder (25), when the outer peripheral wall of the follow-up piston (4) abuts against the inner ring of the second sealing ring (8), the above-mentioned rear axle pressure cavity (211) is formed between one end of the auxiliary piston (5) and the follow-up piston (4).

6. The brake structure of the brake valve according to any one of claims 1 to 4, characterized by The auxiliary piston (5) is sleeved with a compression spring (9) and a third sealing ring (10) away from the trailing piston (4), the longitudinal section of the third sealing ring (10) is D-shaped, the outer ring of the third sealing ring (10) abuts against the cavity wall of the rear cavity (22), and the inner ring has a gap with the auxiliary piston (5), one end of the compression spring (9) acts on the auxiliary piston (5), and the other end acts on one side of the third sealing ring (10), the auxiliary piston (5) further has a second limiting surface (52), the second limiting surface (52) and the other side of the third sealing ring (10) have an oil blocking gap (11) in communication with the oil inlet (23) of the rear cavity (22), when the auxiliary piston (5) moves away from the trailing piston (4), the second limiting surface (52) can abut against the other side of the third sealing ring (10) to form the above-mentioned front axial pressure cavity (221) between the end of the auxiliary piston (5) and the inner cavity wall of the upper valve body (2).

7. The brake structure of the brake valve according to claim 6, characterized by The auxiliary piston (5) has a contraction section (53) in a column shape and a flow guide section (54) in a cone shape, the third sealing ring (10) is sleeved on the contraction section (53), the large end face of the flow guide section (54) is the above-mentioned second limiting surface (52), the auxiliary piston (5) further has a third limiting surface (55) at the oil inlet (23) of the rear cavity (22), the flow guide section (54) is sleeved with a flow limiting piece (12), the flow limiting piece (12) is slidingly connected between the third sealing ring (10) and the third limiting surface (55), and the flow limiting piece (12) and the flow guide section (54) form an oil control gap (13) in communication with the oil inlet (23) of the rear cavity (22) and the oil blocking gap (11).

8. The brake structure of the brake valve according to claim 7, characterized by The auxiliary piston (5) further has a sliding section (56) abutting against the cavity wall of the rear cavity (22), the sliding section (56) is connected with the small end of the flow guide section (54) to form the above-mentioned third limiting surface (55), the auxiliary piston (5) is provided with a drainage hole (58) extending from the sliding section (56) to the flow guide section (54) in the radial direction, the drainage hole (58) is in communication with the oil inlet (23) of the rear cavity (22) and the oil control gap (13), the cross section of the flow limiting piece (12) is annular, the outer end of the flow limiting piece (12) is in gap fit with the upper valve body (2), and the inner ring of the flow limiting piece (12) is provided with a second annular groove (121).

9. The brake structure of the brake valve according to claim 8, characterized by The auxiliary piston (5) further has an extension section (57) connected with the sliding section (56), the extension section (57) and the cavity wall of the rear cavity (22) have an oil storage gap (14), and the sliding section (56) is provided with a pressure relief groove (561) in communication with the oil storage gap (14) and the drainage hole (58).

10. The brake structure of the brake valve according to any one of claims 1 to 4, characterized by The brake structure further comprises a compression spring two (15) located in the front cavity (21), two ends of the compression spring two (15) acting on the follow-up piston (4) and the auxiliary piston (5) respectively, and further comprises a compression spring three (16) located in the rear cavity (22), two ends of the compression spring three (16) acting on the auxiliary piston (5) and the rear cavity (22) cavity wall respectively, and the compression spring three (16) has a greater elastic force than the compression spring two (15).

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