Double-cavity hydraulic control pressure selection brake valve

Abstract

The utility model relates to the technical field of big horsepower tractor braking system, concretely relates to a double -cavity liquid control pressure selection brake valve, including valve body, the valve body includes first valve cavity and second valve cavity, is equipped with the pressure building balance hole subassembly, pressure selection valve, third brake oil mouth FB on the valve body, with first valve cavity and second valve cavity all intercommunication's oil tank oil mouth T, with first pressure oil mouth P1 and first brake oil mouth B1 and second pressure oil mouth P2 and second brake oil mouth B2 that communicate with second valve cavity, pressure selection valve and first brake oil mouth B1, second brake oil mouth B2 and third brake oil mouth FB intercommunication, second valve cavity has the same brake valve assembly with the structure in first valve cavity in. Through the intercommunication of pressure selection valve and third brake oil mouth FB, make tractor front axle brake and trailer brake share rear axle low pressure end hydraulic oil, solved the problem of big horsepower tractor bilateral brake oil supply shortage.

Description

Technical Field

[0001] This utility model relates to the technical field of braking systems for high-horsepower tractors, specifically to a dual-chamber hydraulic pressure selector brake valve. Background Technology

[0002] High-horsepower tractors, with their powerful engines, wide applicability, and stable performance, have become indispensable equipment in modern agricultural production. However, with the continuous increase in horsepower, braking problems have also arisen: on the one hand, under straight-line driving conditions, the braking distance is long, and the braking process is unstable or prone to uneven braking; on the other hand, when turning or making a U-turn in small spaces such as fields, insufficient braking flexibility requires multiple adjustments to complete the maneuver, resulting in low work efficiency and high fuel consumption. To balance straight-line braking stability and steering flexibility, existing technologies often employ dual-chamber brake valves to achieve single-sided braking assist steering and bilateral synchronous braking functions. However, the two brake chambers of traditional dual-chamber brake valves are independent of each other. When the driver applies inconsistent force to the left and right pedals, the braking pressure of the two chambers will differ, causing the vehicle to veer off course and seriously affecting handling safety.

[0003] To address the issue of differing braking pressures between the two chambers, an improved solution has been developed in the industry: a parallel dual-chamber design. For example, patent application CN 110789509 A, entitled "A Mechanical Dual-Cavity Balanced Brake Valve," illustrates this. It employs a parallel dual-chamber design with a flexible check piston to achieve consistent braking pressure during bilateral braking and isolation of the chambers to assist steering during unilateral braking. However, this solution still has shortcomings in practical applications: in the parallel dual-chamber operation mode, limited by the valve body's internal structure and flow channel design, the dual-chamber brake valve can only supply a limited amount of oil to the front and rear axle brakes, making it difficult to meet the oil demand of high-horsepower tractors with high braking pressure torque. Utility Model Content

[0004] The purpose of this invention is to provide a dual-chamber hydraulic pressure selector brake valve to solve the existing technical problems mentioned above.

[0005] The technical solution provided by this utility model is as follows: A dual-chamber hydraulic pressure-selective brake valve is provided, including a valve body, in which a first valve chamber and a second valve chamber are formed. The valve body is provided with a pressure-building balance hole assembly, a pressure selection valve, a third brake oil port FB, an oil tank port T communicating with both the first and second valve chambers, a first pressure oil port P1 and a first brake oil port B1 communicating with the first valve chamber, and a second pressure oil port P2 and a second brake oil port B2 communicating with the second valve chamber. The pressure selection valve is connected to the first brake oil port B1, the second brake oil port B2 and the third brake oil port FB. The other end of the first brake oil port B1 is connected to the left rear axle brake, the other end of the second brake oil port B2 is connected to the right rear axle brake, and the other end of the third brake oil port FB is connected to the front axle brake and the trailer brake. A first brake valve assembly is provided in the first valve chamber, and a second brake valve assembly is provided in the second valve chamber. Both the first and second brake valve assemblies include a main valve core and an operating mechanism that drives the main valve core to move axially. When the operating mechanisms of the first brake valve assembly and the second brake valve assembly brake simultaneously, both the first main valve core and the second main valve core are in the lower working position and are in a braking state. The first brake oil port B1 and the first pressure oil port P1 are connected, and the second brake oil port B2 and the second pressure oil port P2 are connected. The first brake oil port B1 and the second brake oil port B2 are connected through the pressure balance hole assembly. The pressure selection valve connects the third brake oil port FB to the low-pressure end of the first brake oil port B1 and the second brake oil port B2. When the operating mechanism of one of the brake valve assemblies brakes alone, the corresponding main valve core is in the lower working position and in the braking state, while the main valve core of the other brake valve assembly is in the upper working position and in the depressurized state. The brake oil port in the braking state is connected to the corresponding pressure oil port, and the brake oil port in the depressurized state is simultaneously connected to the oil tank port T and the third brake oil port FB.

[0006] Based on the above technical solution, the pressure selection valve includes a valve core, a third pressure chamber formed on the valve body, and a first pressure chamber, an intermediate channel, and a second pressure chamber connected in sequence. The third pressure chamber is connected to the intermediate channel, the first pressure chamber is connected to the first brake oil port B1, the second pressure chamber is connected to the second brake oil port B2, and the third pressure chamber is connected to the third brake oil port FB. The inner diameter of the intermediate channel is smaller than the inner diameters of the first and second pressure chambers. A first sealing surface is formed radially outward at the connection between the intermediate channel and the first pressure chamber, and a second sealing surface is formed radially outward at the connection between the intermediate channel and the second pressure chamber. The left end of the valve core is located in the first pressure chamber and a first soft sealing ring is fitted on its outer side. The right end of the valve core is located in the second pressure chamber and a second soft sealing ring is fitted on its outer side. The outer diameters of both the first and second soft sealing rings are larger than the inner diameter of the intermediate channel. The distance between the end faces of the first and second soft sealing rings near the intermediate channel is greater than the length of the intermediate channel. The middle part of the valve core is located in the intermediate channel and a guide groove is provided on its outer side.

[0007] Preferably, the outer surface of the first main valve core is provided with a first annular groove; When the first main valve core is in the upper working position, the first annular groove connects the oil tank port T and the first brake port B1. When the first main valve core is in the lower working position, the first annular groove connects the first pressure port P1 and the first brake port B1. When the second main valve core is in the upper working position, the second annular groove connects the oil tank port T and the second brake port B2. When the second main valve core is in the lower working position, the second annular groove connects the second pressure port P2 and the second brake port B2.

[0008] Based on the above technical solution, the pressure building balance hole assembly includes a first balance throttling hole, a balance conducting main hole, and a second balance throttling hole connected in sequence. The first main valve core is provided with a first pilot hole and a third pilot hole inside. The outer side of the first main valve core is provided with a third annular groove. The first annular groove and the third annular groove are connected in sequence through the first pilot hole and the third pilot hole. When the operating mechanisms of the first brake valve assembly and the second brake valve assembly brake simultaneously, the third annular groove is connected to the first balance throttling hole, and the fourth annular groove is connected to the second balance throttling hole.

[0009] Preferably, the valve core body includes a first sealing valve core and a second sealing valve core, which abut against each other in an intermediate channel.

[0010] Preferably, the operating mechanism of the first brake valve assembly includes a first copper sleeve, a first push rod, a first push rod sleeve, a first spring, a first pressure regulating spring assembly, and a second spring assembly. The bottom of the first push rod abuts against the top of the first push rod sleeve. A first dustproof sleeve is provided between the outer end faces of the first push rod and the first push rod sleeve. The outer side of the first push rod sleeve is fitted with the first copper sleeve and is axially movable to the first copper sleeve. The first copper sleeve is fixedly connected to the valve body. The bottom of the first push rod sleeve is recessed inward along the axial direction to form a first inverted U-shaped groove. The first spring and the first pressure regulating spring assembly are both located in the first inverted U-shaped groove. The two ends of the first spring abut against the top and bottom of the first inverted U-shaped groove, respectively. The upper end of the first pressure regulating spring assembly abuts against the top of the first inverted U-shaped groove. The lower end of the first pressure regulating spring assembly abuts against the top of the first main valve core. The second spring assembly abuts against the bottom of the first main valve core.

[0011] Based on the above technical solution, the operating mechanism of the first brake valve assembly further includes a first positioning sleeve. The first positioning sleeve is fixedly connected to the valve body. The first positioning sleeve is sleeved on the upper part of the outer side of the first main valve core. The first positioning sleeve is movably connected to the first main valve core. The inner side of the first positioning sleeve is provided with a first step surface. The outer side of the first main valve core is provided with a first step angle. When the first main valve core is in the upper working position, the first step angle abuts against the first step surface.

[0012] Preferably, the first pressure regulating spring assembly includes a first pressure regulating spring and a first spring seat. One end of the first pressure regulating spring abuts against the top of the first inverted U-shaped groove, and the other end of the first pressure regulating spring abuts against the first spring seat. The top of the first main valve core is provided with a first conical groove, and a first positioning steel ball is provided between the bottom of the first spring seat and the first conical groove. The first positioning steel ball is rotatably abutted between the first spring seat and the first main valve core.

[0013] Preferably, the second spring assembly includes a first screw plug, a second spring, and a second spring seat. The first screw plug is fixedly disposed at the bottom of the valve body, and a fixing groove is provided above the first screw plug. The second spring seat is located in the fixing groove and is fixedly connected to the first screw plug. A first lower stop is provided below the first main valve core. The upper end of the second spring is sleeved outside the first lower stop and abuts against the first main valve core. The lower end of the second spring is sleeved outside the second spring seat and abuts against the bottom of the second spring seat.

[0014] Based on the above technical solution, a first feedback cavity is formed between the first screw plug and the bottom of the valve body, and the first annular groove is connected to the first feedback cavity through the first pilot hole.

[0015] The beneficial effects of the technical solution provided by this utility model are as follows: During bilateral braking, by connecting the pressure selection valve and the third brake oil port FB, the low-pressure end of the front axle brake and trailer brake is connected to the rear axle brake. The tractor's front axle brake and trailer brake share the low-pressure end hydraulic oil, thus solving the problem of insufficient brake oil supply for high-horsepower tractors. Attached Figure Description

[0016] Figure 1 This is a front view of the present invention; Figure 2 This is a side view of the present invention; Figure 3 This is a rear view of the present invention; Figure 4 yes Figure 1 Schematic diagram of the cross-sectional structure along the CC direction; Figure 5 yes Figure 1 Schematic diagram of the cross-sectional structure along the LL direction; Figure 6 yes Figure 2 Schematic diagram of the cross-sectional structure along the BB direction; Figure 7 yes Figure 3 Schematic diagram of the cross-sectional structure along the AA direction; Figure 8 yes Figure 1 Schematic diagram of the cross-sectional structure along the DD direction; Figure 9 This is a schematic diagram of the structure of the first main valve core in this utility model; Figure 10 yes Figure 6 A partially enlarged schematic diagram of the first brake valve assembly. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0018] In the description of this utility model, it should be understood that the terms "left", "right", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] like Figures 1 to 10 As shown, a dual-chamber hydraulic pressure-selective brake valve includes a valve body 1, within which a first valve chamber and a second valve chamber are formed. The valve body 1 is provided with a pressure-balance hole assembly, a pressure selection valve, a third brake port FB, a tank port T communicating with both the first and second valve chambers, a first pressure port P1 and a first brake port B1 communicating with the first valve chamber, and a second pressure port P2 and a second brake port B2 communicating with the second valve chamber. The pressure selection valve is connected to the first brake port B1, the second brake port B2, and the third brake port FB. The other end of the first brake port B1 is connected to the left rear axle brake, the other end of the second brake port B2 is connected to the right rear axle brake, and the other end of the third brake port FB is connected to the front axle brake and the trailer brake.

[0020] The first valve chamber is provided with a first brake valve assembly, which includes a first main valve core 4 and an operating mechanism that drives the first main valve core 4 to move axially.

[0021] The first main valve core 4 has a first annular groove 41 on its outer surface. When the first main valve core 4 is in the upper working position, the first annular groove 41 connects the oil tank port T and the first brake port B1. When the first main valve core 4 is in the lower working position, the first annular groove 41 connects the first pressure port P1 and the first brake port B1. The first main valve core 4 has a first pilot hole 42 and a third pilot hole 44 inside, and a third annular groove 45 on its outer surface. The first annular groove 41 and the third annular groove 45 are connected sequentially through the first pilot hole 42 and the third pilot hole 44.

[0022] The operating mechanism of the first brake valve assembly includes a first copper sleeve 27, a first push rod 21, a first push rod sleeve 22, a first spring 24, a first pressure regulating spring assembly, and a second spring assembly. The bottom of the first push rod 21 abuts against the top of the first push rod sleeve 22. A first dustproof sleeve 23 is provided between the outer end faces of the first push rod 21 and the first push rod sleeve 22, which serves to seal and prevent dust. The first copper sleeve 27 is fitted on the outer side of the first push rod sleeve 22 and is axially movable to the first copper sleeve 27. The first copper sleeve 27 is fixedly connected to the valve body 1. The bottom of the first push rod sleeve 22 is recessed inward along the axial direction to form a first inverted U-shaped groove 221. The first spring 24 and the first pressure regulating spring assembly are both located in the first inverted U-shaped groove 221. The two ends of the first spring 24 abut against the top and bottom of the first inverted U-shaped groove 221, respectively. The upper end of the first pressure regulating spring assembly abuts against the top of the first inverted U-shaped groove 221, and the lower end of the first pressure regulating spring assembly abuts against the top of the first main valve core 4. When the pedal is pressed down, the first push rod 21 pushes the first push rod sleeve 22 to move downward against the force of the first spring 24, thereby driving the first pressure regulating spring assembly and the first main valve core 4 to move downward and achieve braking.

[0023] The operating mechanism of the first brake valve assembly also includes a first positioning sleeve 8, which is fixedly connected to the valve body 1. The first positioning sleeve 8 is sleeved on the upper part of the outer side of the first main valve core 4. The first positioning sleeve 8 is movably connected to the first main valve core 4. The inner side of the first positioning sleeve 8 is provided with a first step surface 81, and the outer side of the first main valve core 4 is provided with a first step angle 46. When the first main valve core 4 is in the upper working position, the first step angle 46 abuts against the first step surface 81.

[0024] The first pressure regulating spring assembly includes a first pressure regulating spring 251 and a first spring seat 252. In order to convert the spring force of the first pressure regulating spring 251 into an axial thrust on the first main valve core 4, one end of the first pressure regulating spring 251 abuts against the top of the first inverted U-shaped groove 221, and the other end of the first pressure regulating spring 251 abuts against the first spring seat 252. The top of the first main valve core 4 is provided with a first conical groove 47, and a first positioning steel ball 253 is provided between the bottom of the first spring seat 252 and the first conical groove 47. The first positioning steel ball 253 is rotatably abutted between the first spring seat 252 and the first main valve core 4, which can effectively compensate for the slight axial difference that may exist during installation and movement.

[0025] The second spring assembly abuts against the bottom of the first main valve core 4. Specifically, the second spring assembly includes a first plug 261, a second spring 262, and a second spring seat 263. The first plug 261 is fixedly disposed at the bottom of the valve body 1, and a fixing groove is provided above the first plug 261. The second spring seat 263 is located in the fixing groove and is fixedly connected to the first plug 261. A first lower stop 43 is provided below the first main valve core 4. The upper end of the second spring 262 is sleeved outside the first lower stop 43 and abuts against the first main valve core 4. The lower end of the second spring 262 is sleeved outside the second spring seat 263 and abuts against the bottom of the second spring seat 263. The second spring 262 is used to drive the first main valve core 4 to move upward, cooperating with the first pressure regulating spring 251 to ensure that the first main valve core 4 can quickly and smoothly return to the upper working position after braking.

[0026] A first feedback chamber 7 is formed between the first screw plug 261 and the bottom of the valve body 1. The first annular groove 41 is connected to the first feedback chamber 7 through the first pilot hole 42. The pressure oil of the first brake oil port B1 enters the first feedback chamber 7 through the first pilot hole 42 and acts on the bottom of the first main valve core 4, generating an upward feedback force that is transmitted to the pedal. By adjusting the diameter of the first main valve core 4, the pedal feedback force can be optimized, and the driver's pedal operation force can be improved.

[0027] The second brake valve assembly has the same mechanical structure as the first brake valve assembly, including a second push rod 21', a second push rod sleeve 22', a second dust cover 23', a third spring 24', a second copper sleeve 27', a second pressure regulating spring 251', a second inverted U-shaped groove 221', a third spring seat 252', a second positioning steel ball 253', a second positioning sleeve 8', a second main valve core 4', a second annular groove 41', a second pilot hole 42', a fourth pilot hole 44', a fourth annular groove 45', a second feedback chamber 7', a fourth screw plug 261', a fourth spring 262', and a fourth spring seat 263'. Its working principle is the same as that of the first brake valve assembly, independently controlling the oil circuit opening and closing and pressure building of the second brake oil port B2.

[0028] The pressure-building balance hole assembly includes a first balance throttle hole 51, a balance main conduction hole 52, and a second balance throttle hole 53 connected in sequence. When the first push rod 21 and the second push rod 21' are pushed downward, the first main valve core 4 and the second main valve core 4' are both in the lower working position. The first balance throttle hole 51 is connected to the third annular groove 45, and the second balance throttle hole 53 is connected to the fourth annular groove 45', connecting the first braking circuit B1 and the second braking circuit B2. This ensures that the oil pressure of the first braking circuit B1 and the second braking circuit B2 is consistent, ensuring that the braking pressure of the left rear axle brake and the right rear axle brake is consistent during bilateral braking, preventing vehicle braking deviation and ensuring the safety and stability of the vehicle when driving straight.

[0029] The pressure selection valve includes a valve core, a third pressure chamber 13 formed on the valve body 1, and a first pressure chamber 11, an intermediate channel 14, and a second pressure chamber 12 connected in sequence. The third pressure chamber 13 is connected to the intermediate channel 14. The first pressure chamber 11 is connected to the first brake fluid port B1, the second pressure chamber 12 is connected to the second brake fluid port B2, and the third pressure chamber 13 is connected to the third brake fluid port FB. The inner diameter of the intermediate channel 14 is smaller than the inner diameters of the first pressure chamber 11 and the second pressure chamber 12. A first sealing surface 113 is formed at the connection between the intermediate channel 14 and the first pressure chamber 11, extending radially outward. A second sealing surface 123 extends radially outward from the connection point between the valve core 14 and the second pressure chamber 12. The left end of the valve core is located inside the first pressure chamber 11 and is fitted with a first soft sealing ring 611 on its outer side. The right end of the valve core is located inside the second pressure chamber 12 and is fitted with a second soft sealing ring 621 on its outer side. The outer diameters of both the first soft sealing ring 611 and the second soft sealing ring 621 are larger than the inner diameter of the intermediate channel 14. The distance between the end faces of the first soft sealing ring 611 and the second soft sealing ring 621 near the intermediate channel 14 is greater than the length of the intermediate channel 14. The middle part of the valve core is located inside the intermediate channel 14 and is provided with a guide groove 63 on its outer side. Preferably, the valve core includes a first sealing valve core 61 and a second sealing valve core 62, which abut against each other inside the intermediate channel 14. When the braking pressure of the first pressure chamber 11 is greater than the braking pressure of the second pressure chamber 12, the pressure selection valve is in the right working position, the end face of the first soft sealing ring 611 near the middle channel 14 abuts against and seals the first sealing surface 113, and the second pressure chamber 12 is connected to the third pressure chamber 13 through the guide groove 63. When the braking pressure of the first pressure chamber 11 is less than the braking pressure of the second pressure chamber 12, the pressure selection valve is in the left working position, the end face of the second soft sealing ring 621 near the middle channel 14 abuts against and seals the second sealing surface 123, and the first pressure chamber 11 is connected to the third pressure chamber 13 through the guide groove 63.

[0030] Simultaneously, when the first push rod 21 and the second push rod 21' are pushed downward, both the first main valve core 4 and the second main valve core 4' are in the lower working position. The pressure selection valve connects the third pressure chamber 13 with the low-pressure ends of the first pressure chamber 11 and the second pressure chamber 12, thereby connecting the third brake oil port FB with the low-pressure ends of the first brake oil port B1 and the second brake oil port B2. This connects the low-pressure ends of the front axle brake and the trailer brake with the rear axle brake. By sharing the low-pressure end hydraulic oil source, the tractor's front axle brake and trailer brake solve the problem of insufficient brake oil supply for high-horsepower tractors.

[0031] The first pressure chamber 11 has a first opening on the valve body, which is sealed by a second screw plug 111. The second pressure chamber 12 has a second opening on the valve body, which is sealed by a third screw plug 121, which facilitates the installation and maintenance of the pressure selection valve.

[0032] The first pressure chamber 11 is provided with a first limiting post 112. The left end of the first limiting post 112 is fixedly connected to the right end of the second screw plug 111 through a first fixing platform to limit the end point of the pressure selection valve in the left working position. The second pressure chamber 12 is provided with a second limiting post 122. The right end of the second limiting post 122 is fixedly connected to the left end of the third screw plug 121 through a second fixing platform to limit the end point of the pressure selection valve in the right working position.

[0033] Work process: (1) Straight-line braking condition The driver simultaneously depresses the left and right pedals (or the linkage mechanism operates simultaneously), pushing the first push rod 21 and the second push rod 21' downwards. The first push rod 21 pushes the first push rod sleeve 22 downwards, and the downward movement of the first push rod sleeve 22 compresses the first spring 24 and the first pressure regulating spring 251. The first pressure regulating spring 251 pushes the first spring seat 252 downwards, transmitting the force to the first main valve core 4 through the first positioning steel ball 253, overcoming the resistance of the second spring 262, and causing the first main valve core 4 to move from the upper working position to the lower working position. The second push rod 21' pushes the second push rod sleeve 22' downwards, and the downward movement of the second push rod sleeve 22' compresses the third spring 24' and the second pressure regulating spring 251'. The second pressure regulating spring 251' pushes the third spring seat 252' downwards, transmitting the force to the second main valve core 4' through the second positioning steel ball 253', overcoming the resistance of the fourth spring 262', and causing the second main valve core 4' to move from the upper working position to the lower working position.

[0034] During this process: The first annular groove 41 switches the first brake oil port B1 from the oil tank port T to the first pressure oil port P1, allowing pressurized oil to enter the left brake of the rear axle; the second annular groove 41' switches the second brake oil port B2 from the oil tank port T to the second pressure oil port P2, allowing pressurized oil to enter the right brake of the rear axle and establish braking pressure.

[0035] The first braking circuit B1 is connected to the first balance throttle orifice 51 through the first pilot hole 42, the third pilot hole 44, and the third annular groove 45 in sequence. The second braking circuit B2 is connected to the second balance throttle orifice 53 through the second pilot hole 42', the fourth pilot hole 44', and the fourth annular groove 45' in sequence. The first balance throttle orifice 51 is connected to the second balance throttle orifice 53 through the balance main hole 52, ensuring that the braking pressure of the left brake and the right brake of the rear axle is always equal, and preventing brake deviation.

[0036] The pressure selection valve moves according to the slight pressure difference between the first pressure chamber 11 and the second pressure chamber 12, automatically connecting the third pressure chamber 13 to the low-pressure end in the rear axle brake circuit. The third brake port FB supplies the low-pressure oil from the rear axle to the front axle brake and the trailer brake, solving the problem of insufficient brake oil supply for high-horsepower tractors.

[0037] When the brake is released, the driver releases the pedal. Under the restoring force of the first spring 24 and the second spring 262, the first push rod sleeve 22 and the first main valve core 4 return to their upper working positions. The first annular groove 41 reconnects the first brake oil port B1 with the oil tank port T. Under the restoring force of the third spring 24' and the fourth spring 262', the second push rod sleeve 22' and the second main valve core 4' return to their upper working positions. The second annular groove 41' reconnects the second brake oil port B2 with the oil tank port T. The brake is depressurized and the brake is released.

[0038] (2) Braking conditions during steering or U-turn Taking pressing only the left pedal as an example: The first push rod 21 moves downward, pushing the first push rod sleeve 22 downward. As the first push rod sleeve 22 moves downward, it compresses the first spring 24 and the first pressure adjusting spring 251. The first pressure adjusting spring 251 pushes the first spring seat 252 downward, and the force is transmitted to the first main valve core 4 through the first positioning steel ball 253, overcoming the resistance of the second spring 262, so that the first main valve core 4 moves from the upper working position to the lower working position.

[0039] During this process: The first annular groove 41 switches the first brake oil port B1 from the oil tank port T to the first pressure oil port P1, applying braking force to the left brake of the rear axle. The right brake circuit is not activated, and the second brake oil port B2 is connected to the oil tank port T through the second annular groove 41', maintaining a depressurized state.

[0040] The pressure balance hole assembly is only connected when the first main valve core 4 and the second active valve 4' are both in the lower working position. In the case of single-sided braking, the pressure of the left and right braking circuits is independent of each other.

[0041] Because the pressure in the first pressure chamber 11 is much higher than that in the second pressure chamber 12, the pressure selection valve is in the right working position, which connects the second pressure chamber 12 with the third pressure chamber 13. This connects the third brake oil port FB with the depressurized right brake circuit of the rear axle, preventing the front axle and trailer brakes from establishing effective braking. This avoids unnecessary braking force between the front axle and trailer when turning or making a U-turn, thus preventing interference with driving.

[0042] When the brake is released, the driver releases the left pedal. Under the restoring force of the first spring 24 and the second spring 262, the first push rod sleeve 22 and the first main valve core 4 return to the upper working position. The first annular groove 41 reconnects the first brake oil port B1 with the oil tank port T, the brake is depressurized, and the brake is released.

[0043] The foregoing has shown and described the basic principles and main features of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be regarded as exemplary and non-limiting. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this utility model.

[0044] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A dual-chamber hydraulically controlled pressure selective braking valve, characterized in that, The system includes a valve body (1), which has a first valve chamber and a second valve chamber. The valve body (1) is provided with a pressure balance hole assembly, a pressure selection valve, a third brake oil port FB, an oil tank port T that communicates with both the first and second valve chambers, a first pressure oil port P1 and a first brake oil port B1 that communicate with the first valve chamber, and a second pressure oil port P2 and a second brake oil port B2 that communicate with the second valve chamber. The pressure selection valve communicates with the first brake oil port B1, the second brake oil port B2 and the third brake oil port FB. The other end of the first brake oil port B1 is connected to the left rear axle brake, the other end of the second brake oil port B2 is connected to the right rear axle brake, and the other end of the third brake oil port FB is connected to the front axle brake and the trailer brake. The first valve chamber is provided with a first brake valve assembly, and the second valve chamber is provided with a second brake valve assembly. Both the first brake valve assembly and the second brake valve assembly include a main valve core and an operating mechanism that drives the main valve core to move axially. When the operating mechanisms of the first brake valve assembly and the second brake valve assembly brake simultaneously, the first main valve core (4) and the second main valve core (4') are both in the lower working position and in the braking state. The first brake oil port B1 and the first pressure oil port P1 are connected, and the second brake oil port B2 and the second pressure oil port P2 are connected. The first brake oil port B1 and the second brake oil port B2 are connected through the pressure balance hole assembly. The pressure selection valve connects the third brake oil port FB to the low-pressure end of the first brake oil port B1 and the second brake oil port B2. When the operating mechanism of one of the brake valve assemblies brakes alone, the corresponding main valve core is in the lower working position and in the braking state, while the main valve core of the other brake valve assembly is in the upper working position and in the depressurized state; the brake oil port in the braking state is connected to the corresponding pressure oil port, and the brake oil port in the depressurized state is simultaneously connected to the oil tank port T and the third brake oil port FB.

2. The dual-chamber hydraulically controlled pressure selective braking valve according to claim 1, characterized in that, The pressure selection valve includes a valve core, a third pressure chamber (13) formed on the valve body (1), and a first pressure chamber (11), an intermediate channel (14), and a second pressure chamber (12) connected in sequence. The third pressure chamber (13) is connected to the intermediate channel (14), the first pressure chamber (11) is connected to the first brake oil port B1, the second pressure chamber (12) is connected to the second brake oil port B2, and the third pressure chamber (13) is connected to the third brake oil port FB. The inner diameter of the intermediate channel (14) is smaller than the inner diameters of the first pressure chamber (11) and the second pressure chamber (12). A first sealing surface (113) is formed at the connection between the intermediate channel (14) and the first pressure chamber (11) extending radially outward. (14) A second sealing surface (123) is formed by extending radially outward at the connection with the second pressure chamber (12). The left end of the valve core is located in the first pressure chamber (11) and a first soft sealing ring (611) is sleeved on its outer side. The right end of the valve core is located in the second pressure chamber (12) and a second soft sealing ring (621) is sleeved on its outer side. The outer diameters of the first soft sealing ring (611) and the second soft sealing ring (621) are both greater than the inner diameter of the middle channel (14). The distance between the end faces of the first soft sealing ring (611) and the second soft sealing ring (621) near the middle channel (14) is greater than the length of the middle channel (14). The middle part of the valve core is located in the middle channel (14) and a guide groove (63) is provided on its outer side.

3. The dual-chamber hydraulically controlled pressure selective braking valve according to claim 1, characterized in that, The outer side of the first main valve core (4) is provided with a first annular groove (41); When the first main valve core (4) is in the upper working position, the first annular groove (41) connects the oil tank port T and the first brake port B1. When the first main valve core (4) is in the lower working position, the first annular groove (41) connects the first pressure port P1 and the first brake port B1. When the second main valve core (4') is in the upper working position, the second annular groove (41') connects the oil tank port T and the second brake port B2. When the second main valve core (4') is in the lower working position, the second annular groove (41') connects the second pressure port P2 and the second brake port B2.

4. The dual-chamber hydraulically controlled pressure selective braking valve according to claim 3, characterized in that, The pressure-building balance hole assembly includes a first balance throttling hole (51), a balance conducting main hole (52), and a second balance throttling hole (53) connected in sequence. The first main valve core (4) is provided with a first pilot hole (42) and a third pilot hole (44) inside. The outer side of the first main valve core (4) is provided with a third annular groove (45). The first annular groove (41) and the third annular groove (45) are connected in sequence through the first pilot hole (42) and the third pilot hole (44). When the operating mechanisms of the first brake valve assembly and the second brake valve assembly brake at the same time, the third annular groove (45) is connected to the first balance throttling hole (51), and the fourth annular groove (45') is connected to the second balance throttling hole (53).

5. A dual-chamber hydraulically controlled pressure selective braking valve according to claim 2, characterized in that, The valve core body includes a first sealing valve core (61) and a second sealing valve core (62), which abut against each other in the intermediate channel (14).

6. The dual-chamber hydraulically controlled pressure selective braking valve according to claim 1, characterized in that, The operating mechanism of the first brake valve assembly includes a first copper sleeve (27), a first push rod (21), a first push rod sleeve (22), a first spring (24), a first pressure regulating spring assembly, and a second spring assembly. The bottom of the first push rod (21) abuts against the top of the first push rod sleeve (22). A first dustproof sleeve (23) is provided between the outer end faces of the first push rod (21) and the first push rod sleeve (22). The outer side of the first push rod sleeve (22) is fitted with the first copper sleeve (27) and is axially movable to the first copper sleeve (27). The first copper sleeve (27) is connected to the valve body ( 1) Fixed connection, the bottom of the first push rod sleeve (22) is recessed inward along the axial direction to form a first inverted U-shaped groove (221), the first spring (24) and the first pressure regulating spring assembly are both located in the first inverted U-shaped groove (221), the two ends of the first spring (24) respectively abut against the top and bottom of the first inverted U-shaped groove (221), the upper end of the first pressure regulating spring assembly abuts against the top of the first inverted U-shaped groove (221), the lower end of the first pressure regulating spring assembly abuts against the top of the first main valve core (4), and the second spring assembly abuts against the bottom of the first main valve core (4).

7. A dual-chamber hydraulically controlled pressure selective braking valve according to claim 6, characterized in that, The operating mechanism of the first brake valve assembly also includes a first positioning sleeve (8), which is fixedly connected to the valve body (1). The first positioning sleeve (8) is sleeved on the upper part of the outer side of the first main valve core (4). The first positioning sleeve (8) is movably connected to the first main valve core (4). The inner side of the first positioning sleeve (8) is provided with a first step surface (81), and the outer side of the first main valve core (4) is provided with a first step angle (46). When the first main valve core (4) is in the upper working position, the first step angle (46) abuts against the first step surface (81).

8. A dual-chamber hydraulically controlled pressure selective braking valve according to claim 6, characterized in that, The first pressure regulating spring assembly includes a first pressure regulating spring (251) and a first spring seat (252). One end of the first pressure regulating spring (251) abuts against the top of the first inverted U-shaped groove (221), and the other end of the first pressure regulating spring (251) abuts against the first spring seat (252). The top of the first main valve core (4) is provided with a first conical groove (47). The bottom of the first spring seat (252) and the first conical groove (47) are provided with a first positioning steel ball (253). The first positioning steel ball (253) is rotatably abutted between the first spring seat (252) and the first main valve core (4).

9. A dual-chamber hydraulically controlled pressure selective braking valve according to claim 6, characterized in that, The second spring assembly includes a first screw plug (261), a second spring (262), and a second spring seat (263). The first screw plug (261) is fixedly disposed at the bottom of the valve body (1). A fixing groove is provided above the first screw plug (261). The second spring seat (263) is located in the fixing groove and is fixedly connected to the first screw plug (261). A first lower stop (43) is provided below the first main valve core (4). The upper end of the second spring (262) is sleeved outside the first lower stop (43) and abuts against the first main valve core (4). The lower end of the second spring (262) is sleeved outside the second spring seat (263) and abuts against the bottom of the second spring seat (263).

10. A dual-chamber hydraulically controlled pressure selective braking valve according to claim 9, characterized in that, A first feedback cavity (7) is formed between the first screw plug (261) and the bottom of the valve body (1), and the first annular groove (41) is connected to the first feedback cavity (7) through the first pilot hole (42).

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