Hydraulic brake valve and hydraulic system thereof

Abstract

The invention relates to the technical field of loader brake valves, and discloses a hydraulic brake valve and a hydraulic system thereof.The hydraulic brake valve comprises the hydraulic brake valve, the hydraulic brake valve is composed of a one-way valve, a brake valve set, a brake lamp pressure switch, a low-pressure alarm pressure switch, a shuttle valve, a high-low pressure unloading valve and a throttling hole, and the high-low pressure unloading valve and the throttling hole are integrated; a P port, an A port, a B port, a T port, an LS1 port, an LS port, a low-pressure alarm pressure switch and a brake lamp pressure switch are arranged outside the hydraulic brake valve. A liquid filling valve is omitted, an oil source of the full-hydraulic power braking system is taken from an existing priority valve CF port of equipment, pressure feedback signals are selected through a shuttle valve on a hydraulic braking valve, the pressure feedback signals are transmitted to the priority valve, and liquid filling and energy supplementing of the full-hydraulic power braking system or steering work of a steering system is achieved. The brake has the remarkable advantages of being fast in brake response, low in noise, low in failure rate, high in safety coefficient, compact in structure, low in cost and low in energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of loading machine brake valves, and particularly to a hydraulic brake valve and its hydraulic system. Background Art

[0002] The main components of the existing main hydraulic system of loaders mainly include a fixed-displacement pump, a priority valve, a steering hydraulic system, and a working hydraulic system.

[0003] The braking system is an important part of wheeled mobile equipment and is crucial for the safety of the driver's life and property and the production operation efficiency of the vehicle. The braking system of loaders mainly includes the following two structures: One is the mainly air-over-oil braking system. The main components of this system include an air compressor, a pressure control valve, an oil-water separation device, a one-way valve, an air brake valve, an air-over-oil booster, and corresponding connecting pipelines. This system is relatively complex and has congenital defects such as slow braking response, high noise, high failure rate, and low safety factor. The components of the braking system occupy a large installation space, which is particularly prominent in small equipment. However, due to the relatively low cost, this air-over-oil braking system still has a wide application market, especially in the field of small loaders.

[0004] The other is the full-hydraulic power braking system. The main components of this system include a fixed-displacement pump, a filling valve, a hydraulic brake valve, an accumulator, and corresponding connecting pipelines, etc. This system has the advantages of fast braking response, low noise, low failure rate, and high safety factor, but the cost is relatively high. With the upgrading of the industry, the braking systems of high-value wheeled mobile equipment have been using full-hydraulic power braking systems. Especially in the field of medium and large-sized loaders with high value, the full-hydraulic power braking system has been popularized at present.

[0005] The high price of the full-hydraulic power braking system mainly depends on the filling valve. The filling valve has a complex structure and great difficulty in processing and manufacturing. Moreover, loaders with full-hydraulic power braking systems also have the following problems: First, the oil source of the full-hydraulic power braking system is taken from the fixed-displacement pump of the original main hydraulic system of the equipment. Since the flow rate of the main system fixed-displacement pump is relatively large, the filling valve needs to have sufficient oil passing capacity to ensure low energy consumption. This requires the filling valve to be relatively large, and ultimately the cost of the filling valve will account for half or more of the total cost of the braking system. Second, an additional hydraulic pump is added separately as the oil source for the full-hydraulic power braking system, but adding a hydraulic pump will also increase the cost. The cost of the hydraulic pump and the conventional filling valve will also account for half or more of the total cost. At the same time, it will also bring difficulties to the installation of the hydraulic pump, such as a series of problems like where to take power to drive the hydraulic pump, etc. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a hydraulic brake valve and its hydraulic system, which solves the problems of high manufacturing cost and high energy consumption of the full hydraulic power brake on loaders.

[0007] To achieve the above object, the present invention is realized through the following technical solutions: A hydraulic brake valve, including a hydraulic brake valve, which is composed of a check valve, a brake valve group, a brake light pressure switch, a low-pressure alarm pressure switch, a shuttle valve, a high and low pressure unloading valve, and a throttle orifice, and the high and low pressure unloading valve and the throttle orifice are integrated into one; The outside of the hydraulic brake valve has a P port, an A port, a B port, a T port, an LS1 port, an LS port, a low-pressure alarm pressure switch, and a brake light pressure switch; The P port of the hydraulic brake valve is a liquid filling and inlet port, used to connect to the CF port of the priority valve; The A port of the hydraulic brake valve is a pressure maintaining oil port, used to connect to the accumulator; The B port of the hydraulic brake valve is a brake output oil port, used to connect to the axle brake; The T port of the hydraulic brake valve is an oil return port, used to connect to the fuel tank; The LS1 port of the hydraulic brake valve is a feedback port, used to connect to the LS port of the steering gear; The LS port of the hydraulic brake valve is a feedback port, used to connect to the LS port of the priority valve.

[0008] Preferably, the low-pressure alarm pressure switch of the hydraulic brake valve is used for low-pressure alarm and is connected to the alarm; The brake light pressure switch of the hydraulic brake valve is used to control the service brake light and is connected to the brake light; The inside of the hydraulic brake valve also integrates a check valve, a shuttle valve, a high and low unloading valve, a brake valve group, and a throttle orifice; The check valve of the hydraulic brake valve is used for pressure maintaining of the brake system, ensuring that the oil in the accumulator connected to the A port of the hydraulic brake valve cannot be depressurized too quickly; The shuttle valve of the hydraulic brake valve is used to select the larger of the pressure of the LS1 port and the pressure of the P port of the hydraulic brake valve, and is output from the LS port of the hydraulic brake valve, and finally acts on the LS port of the priority valve; The high and low pressure unloading valve of the hydraulic brake valve is used to ensure that the accumulator connected to the A port of the hydraulic brake valve always maintains within a certain pressure range; When the brake valve group does not work, the B port and the T port of the hydraulic brake valve are communicated through the brake valve group and are connected to the fuel tank through the corresponding connecting pipelines. When the brake valve group works, the A port and the B port of the hydraulic brake valve are communicated through the brake valve group; The brake valve group of the hydraulic brake valve is used to control the brake output pressure; The throttle orifice of the hydraulic brake valve is used to control the flow rate back to the fuel tank.

[0009] A hydraulic brake valve hydraulic system includes a fuel tank, a hydraulic brake valve, an accumulator, and corresponding connecting pipelines; The fuel tank supplies the oil inside to the P port of the priority valve through a fixed-displacement pump. The priority valve supplies the oil to the P port of the steering hydraulic system and the P port of the hydraulic brake valve through the CF port. The priority valve transports the oil to the P port of the working hydraulic system through the EF port Preferably, the working hydraulic system is used to control various working devices. The P port of the working hydraulic system is connected to the EF port of the priority valve, and the working hydraulic system does not cause any impact on the hydraulic system connected to the CF port of the priority valve during operation.

[0010] Preferably, when the pressure sensed by the A port of the hydraulic brake valve drops to the lower limit pressure of the accumulator, the high-low pressure unloading valve closes. The closing of the high-low pressure unloading valve cuts off the internal oil passage from the P port to the T port of the hydraulic brake valve. The pressure oil at the P port of the hydraulic brake valve flows through the throttle orifice, shuttle valve, and LS port of the hydraulic brake valve in sequence, and then acts on the LS port of the priority valve through the corresponding connecting pipelines, causing the pressure at the CF port of the priority valve to rise and filling the accumulator with liquid. When the pressure of the accumulator reaches the upper limit pressure, the high-low pressure unloading valve opens. The opening of the high-low pressure unloading valve connects the internal oil passage from the P port to the T port of the hydraulic brake valve. The pressure oil at the P port of the hydraulic brake valve flows through the throttle orifice, high-low pressure unloading valve, and T port of the hydraulic brake valve in sequence and then returns to the inside of the fuel tank through the corresponding connecting pipelines. The pressure oil at the LS port of the priority valve flows through the LS port, shuttle valve, and high-low pressure unloading valve of the hydraulic brake valve through the corresponding connecting pipelines in sequence. The T port of the hydraulic brake valve returns to the fuel tank through the corresponding connecting pipelines. The pressure at the CF port of the priority valve is relieved to a lower standby pressure to complete the liquid filling. When the pressure of the accumulator drops to the set lower limit pressure, the high-low pressure unloading valve closes to conduct the liquid filling of the accumulator, and this process repeats.

[0011] Preferably, the throttle orifice is used for throttling and ensures that only a small amount of hydraulic oil flows back to the fuel tank when the high-low pressure unloading valve opens; After the pressure at the CF port of the priority valve is relieved, the pressure of the accumulator is always maintained between the set upper limit pressure and lower limit pressure.

[0012] Preferably, the shuttle valve is used for signal pressure selection. When the pressure of the accumulator is lower than the set lower limit pressure, the shuttle valve will select the pressure oil coming from the P port of the hydraulic brake valve as the signal pressure, which acts on the LS port of the priority valve after passing through the LS port of the hydraulic brake valve, and the pressure at the CF port of the priority valve rises to fill the accumulator with liquid; The shuttle valve will select the pressure oil from the LS port of the steering hydraulic system as the signal pressure, and then act on the LS port of the priority valve through the L port of the hydraulic brake valve, causing the pressure at the CF port of the priority valve to rise and thus supplying the required hydraulic oil to the steering hydraulic system.

[0013] Preferably, when the oil pressure inside the accumulator is lower than the set value, the alarm controlled by the low-pressure alarm pressure switch emits an alarm signal. The oil in the accumulator enters the axle brake through the A port of the hydraulic brake valve, the brake valve group, the B port of the hydraulic brake valve, and the corresponding connecting pipelines.

[0014] Preferably, when the pressure at the B port of the hydraulic brake valve rises to the pressure value set by the brake light pressure switch, it will control the operation of the service brake light.

[0015] Preferably, the priority valve is a load-sensitive priority valve with an LS oil port. The LS oil port of the priority valve is used to sense the working pressure signal oil. The priority valve distributes the hydraulic oil supplied by the fixed-displacement pump to the hydraulic systems respectively connected to the CF port and the EF port of the priority valve according to the working pressure signal oil sensed by the LS port, and preferentially satisfies the hydraulic system connected to the CF port of the priority valve.

[0016] The present invention provides a hydraulic brake valve and its hydraulic system. It has the following beneficial effects: By canceling the filling valve in the present invention, the oil source of the full-hydraulic power braking system is taken from the existing CF port of the priority valve of the equipment, and the pressure feedback signal is selected through the shuttle valve on the hydraulic brake valve and transmitted to the priority valve to achieve the filling and energy replenishment of the full-hydraulic power braking system or the steering operation of the steering system, and it has significant advantages such as fast braking response, low noise, low failure rate, high safety factor, compact structure, low cost, and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the hydraulic brake valve and its hydraulic system of the present invention; Figure 2 It is a schematic diagram of the hydraulic brake valve of the present invention.

[0018] Among them, 1, fuel tank; 2, fixed-displacement pump; 3, priority valve; 4, hydraulic brake valve; 5, accumulator; 6, axle brake; 7, steering hydraulic system; 8, working hydraulic system; 4-1, check valve; 4-2, brake valve group; 4-3, brake light pressure switch; 4-4, low-pressure alarm pressure switch; 4-5, shuttle valve; 4-6, high-low pressure unloading valve; 4-7, throttle orifice. DETAILED DESCRIPTION OF THE INVENTION

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0020] Referring Figure 1 and Figure 2 As shown, a hydraulic brake valve and its hydraulic system. The hydraulic system includes an oil tank 1, a fixed-displacement pump 2, a priority valve 3, a hydraulic brake valve 4, an accumulator 5, an axle brake 6, a steering hydraulic system 7, a working hydraulic system 8 and corresponding connecting pipelines.

[0021] The fixed-displacement pump 2 sucks the oil in the oil tank 1 and supplies oil to the P port of the priority valve 3. The priority valve 3 then preferentially supplies a part of the oil to the P port of the steering hydraulic system 7 and the P port of the hydraulic brake valve 4 through the CF port to ensure the steering action and braking action of the equipment; the priority valve 3 supplies another part of the oil to the P port of the working hydraulic system 8 through the EF port to ensure the normal operation of the working components of the equipment.

[0022] The hydraulic brake valve 4 integrates a check valve 4-1, a brake valve group 4-2, a brake lamp pressure switch 4-3, a low-pressure alarm pressure switch 4-4, a shuttle valve 4-5, a high-low pressure unloading valve 4-6 and a throttle orifice 4-7, and has the characteristics of compact structure and convenient installation.

[0023] The accumulator 5 is used to store hydraulic oil to ensure braking stability and to ensure a certain number of effective brakings after power failure to ensure driving safety.

[0024] When the pressure at port A of the hydraulic brake valve 4 senses that the pressure of the accumulator 5 has dropped to the set lower limit pressure, the high and low pressure unloading valve 4-6 closes. The closing of the high and low pressure unloading valve 4-6 will cut off the internal oil passage from port P to port T of the hydraulic brake valve 4. The pressure oil at port P of the hydraulic brake valve 4 flows through the damping hole 4-7, shuttle valve 4-5, and port LS of the hydraulic brake valve 4 in sequence, and then acts on port LS of the priority valve 3 through the corresponding connecting pipeline, causing the pressure at port CF of the priority valve 3 to rise, thereby filling the accumulator 5 with liquid. When the pressure of the accumulator 5 reaches the set upper limit pressure, the high and low pressure unloading valve 4-6 opens. The opening of the high and low pressure unloading valve 4-6 will connect the internal oil passage from port P to port T of the hydraulic brake valve 4. The pressure oil at port P of the hydraulic brake valve 4 flows through the throttle hole 4-7, high and low pressure unloading valve 4-6, and port T of the hydraulic brake valve 4 in sequence, and then returns to the fuel tank 1 through the corresponding connecting pipeline. The pressure oil at port LS of the priority valve 3 flows through port LS of the hydraulic brake valve 4, shuttle valve 4-5, high and low pressure unloading valve 4-6, and port T of the hydraulic brake valve 4 in sequence through the corresponding connecting pipeline and then returns to the fuel tank 1 through the corresponding connecting pipeline. The pressure at port CF of the priority valve 3 is depressurized to a lower standby pressure, completing the liquid filling. It is not until the pressure of the accumulator 5 drops to the set lower limit pressure that the high and low pressure unloading valve 4-6 will close to fill the accumulator 5 with liquid, and so on repeatedly.

[0025] The throttle hole 4-7 is used for throttling to ensure that when the high and low pressure unloading valve 4-6 opens, only a small amount of hydraulic oil flows back to the fuel tank, preventing energy waste and reducing energy consumption.

[0026] The one-way valve 4-1 is used for pressure holding to ensure that after the liquid filling is completed and the pressure at port CF of the priority valve 3 is depressurized, the pressure of the accumulator 5 is always maintained between the set upper limit pressure and lower limit pressure.

[0027] The shuttle valve 4-5 is used for signal pressure selection. When the pressure of the accumulator 5 is lower than the set lower limit pressure, the shuttle valve 4-5 will select the pressure oil coming from port P of the hydraulic brake valve 4 as the signal pressure. After passing through port LS of the hydraulic brake valve 4, it acts on port LS of the priority valve 3, causing the pressure at port CF of the priority valve 3 to rise, thereby filling the accumulator 5 with liquid. When the steering hydraulic system 7 is working, the shuttle valve 4-5 will select the pressure oil coming from port LS of the steering hydraulic system as the signal pressure. After passing through port LS of the hydraulic brake valve 4, it acts on port LS of the priority valve 3, causing the pressure at port CF of the priority valve 3 to rise, thereby providing the required hydraulic oil for the steering hydraulic system 7. When the accumulator 5 needs to be filled with liquid and the steering hydraulic system 7 also needs to work, the shuttle valve 4-5 will select the one with the larger pressure as the signal pressure. After passing through port LS of the hydraulic brake valve 4, it acts on port LS of the priority valve 3, causing the pressure at port CF of the priority valve 3 to rise to meet the liquid filling requirements of the accumulator 5 and the working requirements of the steering hydraulic system 7.

[0028] The low-pressure alarm pressure switch 4-4 is used for low-pressure alarm and is connected to the alarm. When the hydraulic pressure in the accumulator 5 is lower than the set value, the alarm controlled by the low-pressure alarm pressure switch 4-4 emits an alarm signal, prompting the driver that there is an abnormality in the braking system and that the vehicle needs to be parked for inspection and repair, playing a role in safety warning.

[0029] The brake valve group 4-2 is used to control the axle brake 6 to decelerate or stop the equipment. When the brake valve group 4-2 is not working, the B port and T port of the hydraulic brake valve 4 are connected through the brake valve group 4-2 and are connected to the fuel tank through the corresponding connecting pipelines. The working pressure of the axle brake 6 is zero, and at this time, the equipment does not perform braking deceleration or stop. When the brake valve group 4-2 is working, the A port and B port of the hydraulic brake valve 4 are connected through the brake valve group 4-2. The hydraulic oil in the accumulator 5 sequentially passes through the A port of the hydraulic brake valve 4, the brake valve group 4-2, the B port of the hydraulic brake valve 4, and the corresponding connecting pipelines to enter the axle brake 6, controlling the axle brake 6 to decelerate and stop the equipment. The braking pressure output from the B port of the hydraulic brake valve 4 is proportional to the driver's operating force. The greater the operating force, the greater the braking pressure output from the B port of the hydraulic brake valve 4. Until the maximum output pressure set by the brake valve group 4-2 is reached, the braking output pressure will be maintained at the maximum braking pressure setting value and will not increase according to the increase in the operating force. The braking deceleration of the equipment will increase according to the increase in the braking pressure.

[0030] The brake light pressure switch 4-3 is used to control the service brake light. After the driver operates the brake valve group 4-2, the pressure at the B port of the hydraulic brake valve 4 will increase. When the pressure at the B port of the hydraulic brake valve 4 rises to the pressure value set by the brake light pressure switch 4-3, the brake light pressure switch 4-3 controls the service brake light to turn on, prompting the surrounding traffic participants that the equipment is braking, playing a role in safety warning.

[0031] The priority valve 3 belongs to a load-sensitive priority valve and has an LS port. The LS port of the priority valve 3 is used to sense the working pressure signal oil. The priority valve 3 distributes the hydraulic pressure supplied by the fixed-displacement pump 2 to the hydraulic systems respectively connected to the CF port and EF port of the priority valve 3 according to the working pressure signal oil sensed by its LS port, and preferentially satisfies the hydraulic system connected to the CF port of the priority valve 3.

[0032] The steering hydraulic system 7 belongs to a load-sensitive steering hydraulic system and has an LS port. The LS port of the steering hydraulic system 7 is used to output pressure signal oil. The LS port of the steering hydraulic system 7 is connected to the LS1 port of the hydraulic brake valve 4 and finally acts on the LS port of the priority valve 3, enabling the CF port of the priority valve 3 to provide the corresponding hydraulic oil as required to ensure the normal operation of the hydraulic system connected to the CF port of the priority valve 3.

[0033] The working hydraulic system 8 is used to control various working devices, such as controlling the lifting of the bucket, etc. The P port of the working hydraulic system 8 is connected to the EF port of the priority valve 3, and when the working hydraulic system 8 works, it does not cause any impact on the hydraulic system connected to the CF port of the priority valve 3.

[0034] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydraulic brake valve, comprising a hydraulic brake valve (4), characterized in that: The hydraulic brake valve (4) is composed of a one-way valve (4-1), a brake valve group (4-2), a brake light pressure switch (4-3), a low-pressure alarm pressure switch (4-4), a shuttle valve (4-5), a high- and low-pressure unloading valve (4-6) and a throttle hole (4-7), wherein the high- and low-pressure unloading valve (4-6) and the throttle hole (4-7) are integrated into one body; The outside of the hydraulic brake valve (4) has a P port, an A port, a B port, a T port, an LS1 port, an LS port, a low pressure alarm pressure switch and a brake light pressure switch; The P port of the hydraulic brake valve (4) is a liquid filling oil inlet port, which is used to connect to the CF port of the priority valve (3); Port A of the hydraulic brake valve (4) is a pressure-maintaining oil port for connecting to an accumulator (5); Port B of the hydraulic brake valve (4) is a brake oil output port, which is used to connect to the axle brake (6); The T port of the hydraulic brake valve (4) is an oil return port, which is used to connect to the oil tank (1); The LS1 port of the hydraulic brake valve (4) is a feedback port, which is used to connect to the LS port of the steering gear; The LS port of the hydraulic brake valve (4) is a feedback port, and is used to connect to the LS port of the priority valve (3).

2. A hydraulic brake valve according to claim 1, characterized in that: The low pressure alarm pressure switch (4-4) of the hydraulic brake valve (4) is used for low pressure alarm and is connected to an alarm; The brake light pressure switch (4-3) of the hydraulic brake valve (4) is used to control the driving brake light and is connected to the brake light; The hydraulic brake valve (4) further includes a one-way valve (4-1), a shuttle valve (4-5), a high and low unloading valve (4-6), a brake valve group (4-2), and a throttle hole integrated therein; The one-way valve (4-1) of the hydraulic brake valve (4) is used to maintain the pressure of the brake system, ensuring that the oil in the accumulator (5) connected to the A port of the hydraulic brake valve (4) cannot release pressure too quickly; The shuttle valve (4-5) of the hydraulic brake valve (4) is used to select the larger of the pressure at the LS1 port of the hydraulic brake valve (4) and the pressure at the P port of the hydraulic brake valve (4), and output the pressure from the LS port of the hydraulic brake valve (4) to finally act on the LS port of the priority valve (3); The high and low pressure unloading valves (4-6) of the hydraulic brake valve (4) are used to ensure that the accumulator (5) connected to the A port of the hydraulic brake valve is always maintained within a certain pressure range; When the brake valve group (4-2) is not in operation, the B port and the T port of the hydraulic brake valve (4) are in communication with each other through the brake valve group (4-2) and are connected to the oil tank (1) through corresponding connecting pipes; when the brake valve group (4-2) is in operation, the A port and the B port of the hydraulic brake valve (4) are in communication with each other through the brake valve group (4-2); The brake valve group of the hydraulic brake valve (4) is used to control the brake output pressure; The throttle hole (4-7) of the hydraulic brake valve (4) is used to control the flow rate flowing back to the oil tank (1).

3. A hydraulic brake valve hydraulic system, characterized in that: A hydraulic brake valve as claimed in any one of claims 1 to 2, further comprising an oil tank (1), a hydraulic brake valve (4), an accumulator (5) and corresponding connecting pipelines; The oil tank (1) supplies the oil inside to the P port of the priority valve (3) through the metering pump (2), the priority valve (3) supplies the oil to the P port of the steering hydraulic system (7) and the P port of the hydraulic brake valve (4) through the CF port, and the priority valve (3) transports the oil to the P port of the working hydraulic system (8) through the EF port.

4. A hydraulic brake valve hydraulic system according to claim 3, characterized in that: The working hydraulic system (8) is used to control various working devices. The P port of the working hydraulic system (8) is connected to the EF port of the priority valve (3). When the working hydraulic system (8) is working, it does not have any influence on the hydraulic system connected to the CF port of the priority valve (3).

5. The hydraulic brake valve hydraulic system according to claim 3, characterized in that: When the A port of the hydraulic brake valve (4) senses that the pressure of the accumulator (5) has dropped to the lower limit pressure, the high and low pressure relief valves (4-6) are closed. The closing of the high and low pressure relief valves (4-6) cuts off the internal oil passage from the P port to the T port of the hydraulic brake valve (4). The pressure oil at the P port of the hydraulic brake valve (4) flows through the throttle hole (4-7), the shuttle valve (4-5), and the LS port of the hydraulic brake valve (4) in sequence, and then acts on the LS port of the priority valve (3) through the corresponding connecting pipeline, so that the pressure at the CF port of the priority valve (3) rises to fill the accumulator (5). When the pressure of the accumulator (5) reaches the upper limit pressure, the high and low pressure relief valves (4-6) are opened. The high and low pressure relief valves (4-6) are opened to connect the internal oil passage from the P port to the T port of the hydraulic brake valve (4). The oil passages are connected to the hydraulic brake valve (4). The pressure oil at the P port of the hydraulic brake valve (4) flows through the throttle hole (4-7), the high and low pressure unloading valve (4-6), the T port of the hydraulic brake valve (4) in sequence, and then returns to the inside of the oil tank (1) through the corresponding connecting pipelines. The pressure oil at the LS port of the priority valve (3) flows through the LS port of the hydraulic brake valve (4), the shuttle valve (4-5) and the high and low pressure unloading valve (4-6) in sequence through the corresponding connecting pipelines. The T port of the hydraulic brake valve (4) returns to the oil tank (1) through the corresponding connecting pipelines. The CF port of the priority valve (3) is depressurized to a lower standby pressure to complete the filling. The pressure of the accumulator (5) drops to a set lower limit pressure, so that the high and low pressure unloading valve (4-6) is closed to fill the accumulator (5), and the operation is repeated.

6. A hydraulic brake valve hydraulic system according to claim 5, characterized in that: The throttle hole (4-7) is used for throttling and ensures that only a small amount of hydraulic oil flows back to the oil tank (1) when the high and low pressure unloading valves (4-6) are opened; After the pressure is released from the CF port of the priority valve (3), the pressure of the accumulator (5) is kept between the set upper limit pressure and the lower limit pressure.

7. The hydraulic brake valve hydraulic system according to claim 5, characterized in that: The shuttle valve (4-5) is used for signal pressure selection. When the pressure of the accumulator (5) is lower than the set lower limit pressure, the shuttle valve (4-5) selects the pressure oil from the P port of the hydraulic brake valve (4) as the signal pressure, passes through the LS port of the hydraulic brake valve (4), and acts on the LS port of the priority valve (3). The pressure of the CF port of the priority valve (3) rises, thereby filling the accumulator (5). The shuttle valve (4-5) selects the pressure oil from the LS port of the steering hydraulic system (7) as the signal pressure, and then acts on the LS port of the priority valve (3) through the L port of the hydraulic brake valve (4), so that the pressure at the CF port of the priority valve (3) rises and the required hydraulic oil is provided to the steering hydraulic system (7).

8. The hydraulic brake valve hydraulic system according to claim 5, characterized in that: When the oil pressure inside the accumulator (5) is lower than a set value, an alarm controlled by a low-pressure alarm pressure switch (4-4) sends out an alarm signal; The oil in the accumulator (5) enters the axle brake (6) through the A port of the hydraulic brake valve (4), the brake valve group (4-2), the B port of the hydraulic brake valve (4) and corresponding connecting pipelines.

9. The hydraulic brake valve hydraulic system according to claim 5, characterized in that: When the pressure at port B of the hydraulic brake valve (4) rises to the pressure value set by the brake light pressure switch (4-3), the driving brake light will be controlled to operate.

10. The hydraulic brake valve hydraulic system according to claim 5, characterized in that: The priority valve (3) is a load-sensitive priority valve having an LS oil port. The LS oil port of the priority valve (3) is used to sense the working pressure signal oil. The priority valve (3) distributes the hydraulic pressure supplied by the metering pump (2) to the hydraulic systems respectively connected to the CF port and the EF port of the priority valve (3) according to the working pressure signal oil sensed by the LS port, and gives priority to the hydraulic system connected to the CF port of the priority valve (3).

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