Hydraulic brake valve and hydraulic system thereof

Abstract

The application relates to the technical field of loader brake valves, and discloses a hydraulic brake valve and a hydraulic system thereof, which comprises a hydraulic brake valve, wherein the hydraulic brake valve is composed of a check valve, a brake valve group, a brake lamp pressure switch, a low-pressure alarm pressure switch, a shuttle valve, a high-low pressure unloading valve and a throttle hole, the high-low pressure unloading valve and the throttle hole are integrated, and the hydraulic brake valve is externally provided with 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. By canceling a liquid filling valve, the oil source of a full-hydraulic power brake system is taken from a priority valve CF port of an existing device, a shuttle valve on the hydraulic brake valve is used for selecting a pressure feedback signal, the pressure feedback signal is transmitted to the priority valve, the full-hydraulic power brake system is filled with liquid and energy is supplemented, or the steering system is used for steering, and the hydraulic brake valve has the advantages of fast brake response, small noise, low failure rate, high safety coefficient, compact structure, low cost, low energy consumption and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of loader brake valve, in particular to a hydraulic brake valve and a hydraulic system thereof. BACKGROUND

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

[0003] The brake system is an important part of the tire-type walking equipment, and is crucial to the life and property safety of the driver and the production efficiency of the vehicle. The brake system of the loader mainly includes the following two structures:

[0004] One is a main air top oil brake system, which mainly includes an air compressor, a pressure control valve, an oil-water separation device, a one-way valve, an air brake valve, an air top oil booster and corresponding connecting pipelines. This system is relatively complex, and has the inherent defects of slow brake response, high noise, high failure rate and low safety factor. The brake system components occupy a large installation space, especially on small equipment. However, due to the relatively low cost, the air top oil brake system still has a wide application market, especially in the field of small loaders.

[0005] The other is a full hydraulic power brake system, which mainly includes a fixed displacement pump, a liquid filling valve, a hydraulic brake valve, an accumulator and corresponding connecting pipelines. This system has the advantages of fast brake response, low noise, low failure rate and high safety factor, but the cost is relatively high. With the upgrading of the industry, the brake system of the tire-type walking equipment with higher value has been using the full hydraulic power brake system, especially in the field of medium and large loaders with higher value. At present, the full hydraulic power brake system has been popularized.

[0006] The high price of the full hydraulic power brake system mainly depends on the liquid filling valve. The liquid filling valve has a complex structure and is difficult to manufacture. In addition, the full hydraulic power brake system loader also has the following problems: 1. The oil source of the full hydraulic power brake system is taken from the original main hydraulic system fixed displacement pump of the equipment. Since the flow of the main system fixed displacement pump is relatively large, the liquid filling valve needs to have sufficient oil passage capacity to ensure low energy consumption. This requires the liquid filling valve to be relatively large, which ultimately leads to the cost of the liquid filling valve accounting for more than half of the total cost of the brake system; 2. An additional hydraulic pump is used as the oil source of the full hydraulic power brake system, but the increase of the hydraulic pump also leads to an increase in cost. The cost of the hydraulic pump and the conventional liquid filling valve also accounts for more than half of the total cost, and at the same time, the installation of the hydraulic pump is difficult, such as where to take power to drive the hydraulic pump and a series of problems. SUMMARY

[0007] In view of the deficiencies of the prior art, the hydraulic brake valve and the hydraulic system thereof are provided to solve the problems of high manufacturing cost and high energy consumption of the full hydraulic power brake on the loader.

[0008] To achieve the above object, the hydraulic brake valve is provided by the following technical scheme: a hydraulic brake valve, which is composed of a check valve, a brake valve group, a brake lamp pressure switch, a low-pressure alarm pressure switch, a shuttle valve, a high-low pressure unloading valve and a throttle hole, the high-low pressure unloading valve and the throttle hole are integrated;

[0009] 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 lamp pressure switch outside;

[0010] The P port of the hydraulic brake valve is a liquid filling oil inlet port for connecting a CF port of a priority valve;

[0011] The A port of the hydraulic brake valve is a pressure maintaining oil port for connecting an accumulator;

[0012] The B port of the hydraulic brake valve is a brake output oil port for connecting an axle brake;

[0013] The T port of the hydraulic brake valve is a return oil port for connecting an oil tank;

[0014] The LS1 port of the hydraulic brake valve is a feedback port for connecting a steering gear LS port;

[0015] The LS port of the hydraulic brake valve is a feedback port for connecting an LS port of a priority valve.

[0016] Preferably, the low-pressure alarm pressure switch of the hydraulic brake valve is used for low-pressure alarm and is connected to an alarm;

[0017] The brake lamp pressure switch of the hydraulic brake valve is used for controlling a running brake lamp and is connected to a brake lamp;

[0018] The hydraulic brake valve further integrates a check valve, a shuttle valve, a high-low unloading valve, a brake valve group and a throttle hole inside;

[0019] The check valve of the hydraulic brake valve is used for pressure maintaining of a brake system and ensures that oil in the accumulator connected to the A port of the hydraulic brake valve cannot be discharged too fast;

[0020] The shuttle valve of the hydraulic brake valve is used for selecting the larger one between the LS1 port pressure of the hydraulic brake valve and the P port pressure of the hydraulic brake valve and outputting from the LS port of the hydraulic brake valve, and finally acting on the LS port of the priority valve;

[0021] The high-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 is always maintained within a certain pressure range.

[0022] The B port and the T port of the hydraulic brake valve are communicated through the brake valve group when the brake valve group is not working, and are communicated with the oil tank through the corresponding connecting pipeline. The A port and the B port of the hydraulic brake valve are communicated through the brake valve group when the brake valve group is working.

[0023] The brake valve group of the hydraulic brake valve is used to control the brake output pressure.

[0024] The throttle hole of the hydraulic brake valve is used to control the flow rate of the flow back to the oil tank.

[0025] A hydraulic brake valve hydraulic system comprises an oil tank, a hydraulic brake valve, an accumulator and corresponding connecting pipelines.

[0026] The oil tank supplies the oil in the interior to the P port of the priority valve through a constant flow 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 delivers the oil to the P port of the working hydraulic system through the EF port.

[0027] 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. The working hydraulic system does not cause any influence on the hydraulic system connected to the CF port of the priority valve when the working hydraulic system is working.

[0028] Preferably, when the pressure of the accumulator decreases to the lower limit pressure, the high-low pressure unloading valve of the hydraulic brake valve is closed. 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 of the P port of the hydraulic brake valve flows through the throttle hole, the shuttle valve and the LS port of the hydraulic brake valve in sequence, and then flows through the corresponding connecting pipeline to the LS port of the priority valve, so that the pressure of the CF port of the priority valve rises to charge the accumulator. When the pressure of the accumulator reaches the upper limit pressure, the high-low pressure unloading valve is opened. 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 of the P port of the hydraulic brake valve flows through the throttle hole, the high-low pressure unloading valve and the T port of the hydraulic brake valve in sequence, and then flows through the corresponding connecting pipeline back to the interior of the oil tank. The pressure oil of the LS port of the priority valve flows through the LS port of the hydraulic brake valve, the shuttle valve and the high-low pressure unloading valve in sequence through the corresponding connecting pipeline. The T port of the hydraulic brake valve flows through the corresponding connecting pipeline back to the oil tank. The CF port of the priority valve is discharged to a lower standby pressure to complete the charging. When the pressure of the accumulator decreases to the set lower limit pressure, the high-low pressure unloading valve is closed to charge the accumulator, and the charging is repeated.

[0029] Preferably, the throttle hole is used for throttling and ensuring that only a small amount of hydraulic oil flows back to the oil tank when the high-low pressure unloading valve is opened.

[0030] The pressure of the accumulator is kept between the upper limit pressure and the lower limit pressure after the CF port of the priority valve is released.

[0031] Preferably, the shuttle valve is used as a signal pressure selector, when the pressure of the accumulator is lower than the lower limit pressure, the shuttle valve selects the pressure oil from the P port of the hydraulic brake valve as the signal pressure, and the signal pressure acts on the LS port of the priority valve through the LS port of the hydraulic brake valve, and the CF port pressure of the priority valve rises to charge the accumulator.

[0032] The shuttle valve selects the pressure oil from the LS port of the steering hydraulic system as the signal pressure, and the signal pressure acts on the LS port of the priority valve through the L port of the hydraulic brake valve, and the CF port pressure of the priority valve rises to provide the required hydraulic oil for the steering hydraulic system.

[0033] Preferably, when the oil pressure in the accumulator is lower than the set value, the alarm of the low pressure alarm pressure switch sends an alarm signal.

[0034] 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 pipeline.

[0035] Preferably, when the B port pressure of the hydraulic brake valve rises to the pressure value set by the brake lamp pressure switch, the brake lamp is controlled to work.

[0036] 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, and the priority valve distributes the hydraulic pressure supplied by the constant flow pump to the hydraulic systems 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 meets the hydraulic system connected to the CF port of the priority valve.

[0037] The present application provides a hydraulic brake valve and a hydraulic system thereof, which has the following advantages:

[0038] The present application cancels the charging valve, and the oil source of the full hydraulic power brake system is taken from the CF port of the existing priority valve of the equipment, and the shuttle valve on the hydraulic brake valve selects the pressure feedback signal, and the pressure feedback signal is transmitted to the priority valve, so that the full hydraulic power brake system is charged and the steering system is steered, and the brake response is fast, the noise is small, the failure rate is low, the safety factor is high, the structure is compact, the cost is low, and the energy consumption is low. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The schematic diagram of the hydraulic brake valve and the hydraulic system thereof of the present application;

[0040] Figure 2 The schematic diagram of the hydraulic brake valve of the present application.

[0041] Wherein, 1, oil 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 lamp pressure switch; 4-4, low pressure alarm pressure switch; 4-5, shuttle valve; 4-6, high and low pressure unloading valve; 4-7, throttle hole. DETAILED DESCRIPTION

[0042] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0043] Referring to Figure 1 and Figure 2 , a hydraulic brake valve and its hydraulic system are shown, which comprises 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.

[0044] The fixed displacement pump 2 supplies oil to the P port of the priority valve 3 after sucking oil in the oil tank 1, and the priority valve 3 supplies 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, so as 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, so as to ensure the normal action of the working parts of the equipment.

[0045] 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 and low pressure unloading valve 4-6 and a throttle hole 4-7, and has the characteristics of compact structure and convenient installation.

[0046] The accumulator 5 is used for storing hydraulic oil, so as to ensure stable braking and a certain number of effective braking after power failure, thereby ensuring driving safety.

[0047] When the pressure of the accumulator 5 decreases to the lower limit pressure, the high-low pressure unloading valve 4-6 is closed, which cuts off the internal oil passage from the P port of the hydraulic brake valve 4 to the T port of the hydraulic brake valve 4. The pressure oil in the P port of the hydraulic brake valve 4 flows through the damping hole 4-7, the shuttle valve 4-5, and the LS port of the hydraulic brake valve 4 in sequence, and then flows through the corresponding connecting pipeline to the LS port of the priority valve 3, so that the pressure of the CF port of the priority valve 3 rises, and the accumulator 5 is filled with liquid. When the pressure of the accumulator 5 reaches the upper limit pressure, the high-low pressure unloading valve 4-6 is opened, which connects the internal oil passage from the P port of the hydraulic brake valve 4 to the T port of the hydraulic brake valve 4. The pressure oil in the P port of the hydraulic brake valve 4 flows through the throttle hole 4-7, the high-low pressure unloading valve 4-6, and the T port of the hydraulic brake valve 4 in sequence, and then flows through the corresponding connecting pipeline back to the oil tank 1. The pressure oil in the LS port of the priority valve 3 flows through the corresponding connecting pipeline, the LS port of the hydraulic brake valve 4, the shuttle valve 4-5, the high-low pressure unloading valve 4-6, and the T port of the hydraulic brake valve 4 in sequence, and then flows through the corresponding connecting pipeline back to the oil tank 1. The pressure of the CF port of the priority valve 3 is released to a lower standby pressure, and the filling is completed. The accumulator 5 is filled with liquid until the pressure of the accumulator 5 decreases to the lower limit pressure, and then the high-low pressure unloading valve 4-6 is closed. The process is repeated.

[0048] The throttle hole 4-7 is used for throttling, which ensures that only a small amount of hydraulic oil flows back to the oil tank when the high-low pressure unloading valve 4-6 is opened, so as to prevent energy waste and reduce energy consumption.

[0049] The one-way valve 4-1 is used for pressure maintenance, which ensures that the pressure of the accumulator 5 is maintained between the upper limit pressure and the lower limit pressure after the filling is completed and the pressure of the CF port of the priority valve 3 is released.

[0050] The shuttle valve 4-5 is used for signal pressure selection. When the pressure of the accumulator 5 is lower than the 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, which acts on the LS port of the priority valve 3 through the LS port of the hydraulic brake valve 4, so that the pressure of the CF port of the priority valve 3 rises, and the accumulator 5 is filled with liquid. When the steering hydraulic system 7 works, the shuttle valve 4-5 selects the pressure oil from the LS port of the steering hydraulic system as the signal pressure, which acts on the LS port of the priority valve 3 through the LS port of the hydraulic brake valve 4, so that the pressure of the CF port of the priority valve 3 rises, and the steering hydraulic system 7 is provided with the required hydraulic oil. 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 selects the pressure with a larger value as the signal pressure, which acts on the LS port of the priority valve 3 through the LS port of the hydraulic brake valve 4, so that the pressure of the CF port of the priority valve 3 rises, to meet the needs of the accumulator 5 and the steering hydraulic system 7.

[0051] Low pressure alarm pressure switch 4-4, low for low pressure alarm, connected to alarm, when the oil pressure in accumulator 5 is lower than the set value, low pressure alarm pressure switch 4-4 controls the alarm to send alarm signal, prompting the driver that the brake system is abnormal, need to stop and check, repair, play the role of safety warning.

[0052] Brake valve group 4-2, used to control axle brake 6, make the equipment decelerate or stop. When brake valve group 4-2 is not working, B port and T port of hydraulic brake valve 4 are connected through brake valve group 4-2, and connected to oil tank through corresponding connecting pipeline, the working pressure of axle brake 6 is zero, at this time the equipment does not decelerate or stop; When brake valve group 4-2 is working, A port and B port of hydraulic brake valve 4 are connected through brake valve group 4-2, the oil in accumulator 5 enters axle brake 6 through A port of hydraulic brake valve 4, brake valve group 4-2, B port of hydraulic brake valve 4 and corresponding connecting pipeline in turn, control axle brake 6, make the equipment decelerate or stop; The output brake pressure of B port of hydraulic brake valve 4 is proportional to the operating force, the greater the operating force, the greater the output brake pressure of B port of hydraulic brake valve 4, until the maximum output pressure set by brake valve group 4-2, the brake output pressure is maintained at the maximum brake pressure set value, and does not increase with the increase of operating force. The deceleration of the equipment will increase with the increase of brake pressure.

[0053] Brake lamp pressure switch 4-3, used to control the running brake lamp. When the driver operates brake valve group 4-2, the pressure of B port of hydraulic brake valve 4 will rise, when the pressure of B port of hydraulic brake valve 4 rises to the pressure value set by brake lamp pressure switch 4-3, brake lamp pressure switch 4-3 controls the running brake lamp to light, prompting the surrounding traffic participants that the equipment is braking, playing the role of safety warning.

[0054] Priority valve 3 belongs to load sensitive priority valve, with LS oil port, LS oil port of priority valve 3 is used to sense working pressure signal oil, priority valve 3 distributes the hydraulic pressure supplied by quantitative pump 2 to the hydraulic systems connected to CF port and EF port of priority valve 3 respectively according to the working pressure signal oil sensed by LS port of priority valve 3, and preferentially meets the hydraulic system connected to CF port of priority valve 3.

[0055] Steering hydraulic system 7 belongs to load sensitive steering hydraulic system, with LS oil port, LS port of steering hydraulic system 7 is used to output pressure signal oil, LS port of steering hydraulic system 7 is connected to LS1 port of hydraulic brake valve 4, finally acts on LS oil port of priority valve 3, makes CF port of priority valve 3 provide corresponding hydraulic oil as required, to meet the normal work of the hydraulic system connected to CF port of priority valve 3.

[0056] The working hydraulic system 8 is used to control various working devices, such as to control the lifting of the bucket. The P port of the working hydraulic system 8 is connected to the EF port of the priority valve 3, and the working of the working hydraulic system 8 does not cause any influence on the hydraulic system connected to the CF port of the priority valve 3.

[0057] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and spirit of the application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A hydraulic brake valve hydraulic system characterized by: The hydraulic brake valve, the oil tank (1), the hydraulic brake valve (4), the accumulator (5) and the corresponding connecting pipeline are included. The hydraulic brake valve (4) is composed of a one-way 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 hole (4-7), wherein the high-low pressure unloading valve (4-6) and the throttle hole (4-7) are integrated; 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 lamp pressure switch outside; The P port of the hydraulic brake valve (4) is a liquid filling oil inlet port, used for connecting the CF port of the priority valve (3); The A port of the hydraulic brake valve (4) is a pressure maintaining oil port, used for connecting the accumulator (5); The B port of the hydraulic brake valve (4) is a brake output oil port, used for connecting the axle brake (6); The T port of the hydraulic brake valve (4) is a return oil port, used for connecting the oil tank (1); The LS1 port of the hydraulic brake valve (4) is a feedback port, used for connecting the LS port of the steering gear; The LS port of the hydraulic brake valve (4) is a feedback port, used for connecting the LS port of the priority valve (3); The oil tank (1) supplies the oil inside to the P port of the priority valve (3) through the quantitative 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) delivers the oil to the P port of the working hydraulic system (8) through the EF port; The A port of the hydraulic brake valve (4) senses the pressure of the accumulator (5) to reduce to the lower limit pressure, and the high-low pressure unloading valve (4-6) is closed, which cuts off the internal oil passage from the P port to the T port of the hydraulic brake valve (4). The pressure oil of the P port of the hydraulic brake valve (4) flows through the throttle hole (4-7), the shuttle valve (4-5), the LS port of the hydraulic brake valve (4) in turn, and then acts on the LS port of the priority valve (3) through the corresponding connecting pipeline, so that the pressure of the CF port of the priority valve (3) rises to charge the accumulator (5). When the pressure of the accumulator (5) reaches the upper limit pressure, the high-low pressure unloading valve (4-6) is opened, which connects the internal oil passage from the P port to the T port of the hydraulic brake valve (4). The pressure oil of the P port of the hydraulic brake valve (4) flows through the throttle hole (4-7), the high-low pressure unloading valve (4-6), the T port of the hydraulic brake valve (4) in turn, and then returns to the internal tank (1) through the corresponding connecting pipeline. The pressure oil of 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-low pressure unloading valve (4-6) in turn through the corresponding connecting pipeline. The T port of the hydraulic brake valve (4) returns to the tank (1) through the corresponding connecting pipeline. The LS port of the priority valve (3) is discharged to a lower standby pressure to complete the charging. The pressure of the accumulator (5) is reduced to the set lower limit pressure to charge the accumulator (5), and the work is repeated.

2. The hydraulic brake valve hydraulic system of claim 1, wherein: The low pressure alarm pressure switch (4-4) of the hydraulic brake valve (4) is used for low pressure alarm, and is connected with an alarm; The brake lamp pressure switch (4-3) of the hydraulic brake valve (4) is used for controlling the running brake lamp, and is connected with a brake lamp; The hydraulic brake valve (4) further integrates a one-way valve (4-1), a shuttle valve (4-5), a high-low unloading valve (4-6), a brake valve group (4-2) and a throttle hole; The one-way valve (4-1) of the hydraulic brake valve (4) is used for brake system pressure maintaining, which ensures that the oil in the accumulator (5) connected with the A port of the hydraulic brake valve (4) cannot be discharged too fast; The shuttle valve (4-5) of the hydraulic brake valve (4) is used for selecting the larger one between the LS1 port pressure of the hydraulic brake valve (4) and the P port pressure of the hydraulic brake valve (4), and outputting from the LS port of the hydraulic brake valve (4) to finally act on the LS port of the priority valve (3); The high-low pressure unloading valve (4-6) of the hydraulic brake valve (4) is used for ensuring that the accumulator (5) connected with the A port of the hydraulic brake valve (4) is always maintained within a certain pressure range; When the brake valve group (4-2) is not working, the B port and the T port of the hydraulic brake valve (4) are communicated through the brake valve group (4-2) and connected with the tank (1) through the corresponding connecting pipeline. When the brake valve group (4-2) is working, the A port and the B port of the hydraulic brake valve (4) are communicated through the brake valve group (4-2); The brake valve group of the hydraulic brake valve (4) is used for controlling the brake output pressure. The throttle hole (4-7) of the hydraulic brake valve (4) is used to control the flow back to the oil tank (1).

3. The hydraulic brake valve hydraulic system of claim 1, wherein: The working hydraulic system (8) is used to control various working devices, and the P port of the working hydraulic system (8) is connected to the EF port of the priority valve (3). The working hydraulic system (8) does not cause any influence on the hydraulic system connected to the CF port of the priority valve (3) when working.

4. The hydraulic brake valve hydraulic system of claim 1, wherein: The throttle hole (4-7) is used for throttling and ensuring that only a small amount of hydraulic oil flows back to the oil tank (1) when the high-low pressure unloading valve (4-6) is opened. The CF port of the priority valve (3) is relieved to keep the pressure of the accumulator (5) between the set upper limit pressure and lower limit pressure.

5. The hydraulic brake valve hydraulic system of claim 1, wherein: The shuttle valve (4-5) is used as a 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, which acts on the LS port of the priority valve (3) through the LS port of the hydraulic brake valve (4), and the CF port pressure of the priority valve (3) rises to charge 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, which acts on the LS port of the priority valve (3) through the L port of the hydraulic brake valve (4), so that the CF port pressure of the priority valve (3) rises to provide the required hydraulic oil for the steering hydraulic system (7).

6. The hydraulic brake valve hydraulic system of claim 1, wherein: When the oil pressure in the accumulator (5) is lower than the set value, the alarm of the low pressure alarm pressure switch (4-4) sends 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 the corresponding connecting pipeline.

7. The hydraulic brake valve hydraulic system of claim 1, wherein: When the B port pressure of the hydraulic brake valve (4) rises to the pressure value set by the brake lamp pressure switch (4-3), the brake lamp will work.

8. The hydraulic brake valve hydraulic system of claim 1, wherein: The priority valve (3) is a load-sensitive priority valve with 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 constant delivery pump (2) to the hydraulic systems 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 preferentially meets the needs of the hydraulic system connected to the CF port of the priority valve (3).

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