Hydraulic braking system for mine wide-body vehicle and control method thereof

Abstract

This invention relates to a hydraulic braking system and control method for a wide-body mining vehicle. The braking system includes a power supply unit, a control unit, and a braking unit. The control unit includes a parking brake control unit and a service brake control unit. The power supply unit directly supplies pressurized oil to the parking brake control unit and supplies pressurized oil to the service brake control unit through a priority valve. The service brake control unit includes a service brake valve, a loading / unloading / emergency brake valve, and a retardation control valve. The power supply unit is connected to the P port of the priority valve, the service brake valve and the loading / unloading / emergency brake valve are connected to the CF port of the priority valve, and the P port of the retardation control valve is connected to the EF port of the priority valve. The outlet pressurized oil of the service brake valve and the loading / unloading / emergency brake valve is fed back to the LS port of the priority valve. When the service brake or emergency brake is applied, the pressure at the LS port increases, which increases the pressure at the CF port and decreases the pressure at the EF port. This ensures that the needs of service brake and emergency brake are prioritized when high-pressure oil is insufficient, thus guaranteeing driving safety.

Description

Technical Field

[0001] This invention belongs to the field of vehicle hydraulic braking systems, specifically relating to a hydraulic braking system and control method for a wide-body mining vehicle. Background Technology

[0002] Mining wide-body trucks are large transport equipment used for earthmoving and transporting sand and gravel in mining areas. When driving on narrow mining roads with dense traffic, bumpy surfaces, and long, steep slopes, these trucks often require frequent braking; this places higher demands on their braking systems. Hydraulic braking systems have become the mainstream braking system for large mining wide-body trucks.

[0003] Existing hydraulic braking systems for mining trucks, such as the hydraulic braking system disclosed in patent CN106809197 entitled "A Hydraulic Braking System for a Mining Dump Truck," have the following problems: When the vehicle is in motion, under extreme conditions such as engine failure or oil pump malfunction, resulting in insufficient pressure, the pressure oil in the braking system cannot meet the needs of various braking modes, especially failing to prioritize service braking. Furthermore, the working environment and nature of mining trucks make them highly susceptible to malfunctions, and the inability to perform service braking in the event of a malfunction can lead to serious consequences. Summary of the Invention

[0004] To ensure the driving safety of mining vehicles, this invention provides a hydraulic braking system and control method for wide-body mining vehicles, which prioritizes vehicle braking in the event of a driving malfunction, thereby ensuring vehicle safety.

[0005] The objective of this invention and the technical problem it solves are achieved through the following technical solution. A hydraulic braking system for a wide-body mining vehicle, according to this invention, includes a power supply unit, a control unit, and a braking unit. The control unit includes a parking brake control unit and a service brake control unit. The power supply unit directly supplies pressurized oil to the parking brake control unit and supplies pressurized oil to the service brake control unit through a priority valve. The service brake control unit includes a service brake valve, a loading / unloading / emergency brake valve, and a retardation control valve. The power supply unit is connected to the P port of the priority valve, the service brake valve and the loading / unloading / emergency brake valve are connected to the CF port of the priority valve, and the P port of the retardation control valve is connected to the EF port of the priority valve. The outlet pressurized oil of the service brake valve and the loading / unloading / emergency brake valve is fed back to the LS port of the priority valve. When the service brake or emergency brake is applied, the pressure at the LS port increases, causing the pressure at the CF port to increase and the pressure at the EF port to decrease. This ensures that the energy supply for service braking and emergency braking is prioritized in the service brake control unit, meeting braking requirements and safety in emergency situations.

[0006] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0007] The aforementioned hydraulic braking system for wide-body mining vehicles includes a braking unit comprising a front axle braking section, a middle and rear axle braking section, and a retarder cylinder. The retarder control valve controls the retarder cylinder and the middle and rear axle braking section's full-disc wet brakes via a second directional valve, and switches between retarder cylinder braking and middle and rear axle braking via the second directional valve to prevent excessive heat from reducing braking capacity and accelerating brake wear.

[0008] In the aforementioned hydraulic braking system for wide-body mining vehicles, when the temperature of either the retarder cylinder brake or the middle and rear axle brake reaches a set value, the system switches to the other brake.

[0009] The aforementioned hydraulic braking system for wide-body mining vehicles includes a front axle braking section comprising a road condition switching valve assembly and a front axle brake. The road condition switching valve assembly includes a wet / slippery surface solenoid valve, a first relay valve, and a third shuttle valve. The input port P of the wet / slippery surface solenoid valve is connected to the service brake valve and the loading / unloading / emergency brake valve; its output port A is connected to the L port of the first relay valve; its output port B is connected to the inlet B of the third shuttle valve; and the inlet A of the third shuttle valve is connected to the A port of the first relay valve. The P port of the first relay valve is connected to the power supply unit. The outlet P of the third shuttle valve is connected to the front axle brake. This allows the road condition switching valve assembly to reduce the front axle braking pressure through the relay valve when encountering a wet / slippery surface. The valve opening and outlet pressure are always proportional to the stroke of the brake valve core, improving driver comfort and vehicle safety.

[0010] The aforementioned hydraulic braking system for wide-body mining trucks includes relay valves, back pressure valve assemblies, and full-disc wet brakes in both the middle and rear axle braking sections. The L ports of the relay valves are connected to the service brake valve and the loading / unloading / emergency brake valve, the P ports are connected to the power supply unit, and the A ports are connected to the back pressure valve assemblies. The back pressure valve assemblies include an adjustable flow valve, a shuttle valve, and an overflow valve. The inlet A of the shuttle valve is connected to the A port of the relay valve, the inlet B is connected to the A port of the full-disc wet brake via the adjustable flow valve, and the outlet P is connected to the B port of the full-disc wet brake. An overflow valve is provided between the inlet B of the shuttle valve and the adjustable flow valve. Each axle of the vehicle uses relay valves to connect to the control unit. The P port of the relay valve installed near the axle is connected to the accumulator in the power supply unit, and the pressure oil is always maintained at the P port. When the vehicle starts braking, the pressure oil at the P port of the relay valve can quickly reach the brake, shortening the braking response time and making braking more rapid.

[0011] The aforementioned hydraulic braking system for wide-body mining vehicles includes a parking brake control unit comprising a parking brake valve. This parking brake valve is connected to the A port of the full-disc wet brake of the middle axle braking section and the rear axle braking section. When the parking brake valve is in the lower position, it also supplies pressurized oil to the control port L of the service brake valve through the first reversing valve, thereby activating the service brake valve and causing the vehicle to enter the box brake, thus working together with the parking brake to maintain vehicle safety.

[0012] The aforementioned hydraulic braking system for wide-body mining vehicles includes a power supply unit comprising a variable displacement pump group and an accumulator. A priority unloading valve is also provided between the variable displacement pump group and the accumulator. When the pressure in the accumulator is lower than a set value, the priority unloading valve connects the oil circuit feeding back to the variable displacement pump group, increasing the pump displacement of the variable displacement pump group. When the pressure in the accumulator reaches the set pressure, the valve disconnects the oil circuit feeding back to the variable displacement pump group, reducing the pump displacement of the variable displacement pump group. The priority unloading valve not only controls the accumulator filling process but also forms feedback with the variable displacement pump group to adjust the displacement of the variable displacement pump group and regulate the real-time output power of the variable displacement pump group, effectively reducing power waste.

[0013] The objective of this invention and the technical problem it solves are achieved by the following technical solution. According to the control method of the hydraulic braking system for a wide-body mining vehicle proposed in this invention, when an emergency occurs during slow braking requiring service braking or emergency braking, the service brake valve or loading / unloading / emergency brake valve is activated. Pressure oil from the power supply unit flows through the P port of the priority valve to the CF and EF ports. Pressure oil at the outlet of the service brake valve or loading / unloading / emergency brake valve is fed back to the LS port of the priority valve, causing the valve core of the priority valve to move towards the EF port. This increases the CF port and decreases the EF port, increasing the pressure oil supplied to the service brake valve or loading / unloading / emergency brake valve and decreasing the oil supplied to the slow control valve. When there is sufficient pressure oil fed back from the LS port, the EF port is completely closed, and all pressure oil is supplied to the service brake valve or loading / unloading / emergency brake valve through the CF port, meeting the braking requirements and ensuring braking safety in emergency situations.

[0014] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0015] The aforementioned control method for the hydraulic braking system of a wide-body mining vehicle involves the following steps: When the vehicle is braking on a normal road surface or undergoing emergency braking, the wet / slippery road surface solenoid valve of the road condition switching valve group is in the lower position. Pressure oil from the power supply unit passes through the wet / slippery road surface solenoid valve and the third shuttle valve sequentially to enter the brake and achieve front axle braking. When the vehicle is braking on a wet / slippery road surface or undergoing emergency braking, the wet / slippery road surface solenoid valve of the road condition switching valve group is in the upper position. Pressure oil from the power supply unit passes through the wet / slippery road surface solenoid valve to enter the L port of the first relay valve. The pressure of the front axle braking is reduced by the first relay valve. The opening of the first relay valve is adjusted by adjusting the stroke of the service brake valve to ensure braking safety on wet / slippery roads.

[0016] The aforementioned control method for the hydraulic braking system of a wide-body mining truck involves the following steps: During service braking or loading / unloading / emergency braking, pressurized oil from the power supply unit enters the back pressure assembly of the middle or rear axle braking section via the first inlet of the relay valve and shuttle valve. From there, it enters port B of the full-disc wet brake via the shuttle valve within the back pressure assembly. During slow braking, pressurized oil from the power supply unit enters the back pressure assembly of the front or rear axle braking section via the slow control valve and the lower position of the second directional valve. From there, it enters port B of the full-disc wet brake via the shuttle valve within the back pressure assembly, achieving braking of the middle and rear axles. During parking braking, the pressurized oil at port A of the full-disc wet brake returns to the oil tank, achieving parking braking. The use of the back pressure valve assembly shortens the distance between the dynamic and static friction pads used for service braking within the full-disc wet brake, making the vehicle's braking response more sensitive.

[0017] The middle axle braking section and the rear axle braking section also include a shuttle valve that connects the relay valve and the back pressure valve group or the second directional valve and the back pressure valve group. Specifically, the inlet A of the shuttle valve is connected to the relay valve, the inlet B is connected to the second directional valve, and the outlet P is connected to the back pressure valve group.

[0018] Compared with the prior art, the present invention has significant advantages and beneficial effects. Through the above technical solution, the present invention achieves considerable technological advancement and practicality, and has broad industrial application value, possessing at least the following advantages:

[0019] This invention ensures energy supply during service braking and emergency braking through the design of a priority valve. In emergency situations such as when the system pressure oil is insufficient and cannot meet the needs of the entire system (e.g., power component failure), the priority valve can prioritize the high-pressure oil to meet the needs of service braking and emergency braking, thus ensuring vehicle safety.

[0020] When braking on wet and slippery roads, the present invention reduces the braking pressure of the front axle by means of a first relay valve, and adjusts the valve opening of the first relay valve by adjusting the stroke of the service brake valve to ensure braking safety on wet and slippery roads.

[0021] During prolonged slow braking, this invention allows for alternating slow braking between the central and rear axle full-disc wet brakes and the slowing device cylinder. This alternating slow braking effectively prevents excessive heat generation from continuous braking of the central and rear axle brakes, which would reduce the friction coefficient and braking performance. The alternating slow braking with the slowing device cylinder also increases the service life of the central and rear axle full-disc wet brakes, improves the consistency of the system's braking efficiency, and effectively ensures the safety of the vehicle when driving downhill.

[0022] The loading and unloading braking of this invention can realize simultaneous braking of the front, middle and rear axles of the vehicle, which can effectively avoid dangers such as slippage during vehicle loading and unloading operations; at the same time, the middle and rear axles are braked by high-pressure oil driving friction linings, which can avoid damage to the parking brake caused by the impact of loading and unloading materials when the parking brake is applied separately.

[0023] This invention integrates vehicle emergency braking and loading / unloading braking into one unit, with their pipelines arranged in a combined manner, which can save on vehicle operating costs and facilitate the integrated design of the entire vehicle.

[0024] The brake valve of this invention only controls the control port of the relay valve of each bridge. Therefore, a lighter brake valve can be selected during the design, reducing the pipeline diameter from the accumulator to the relay valve, saving usage costs, and facilitating subsequent installation and maintenance of the pipeline.

[0025] This invention relates to a full-disc wet brake that integrates service brake and parking brake into one unit, forming a fully sealed structure with strong anti-pollution ability and easy maintenance, meeting the braking needs of vehicles operating in harsh mining environments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the hydraulic braking system for the wide-body mining vehicle of the present invention;

[0027] Figure 2 Hydraulic schematic diagram of the power supply unit;

[0028] Figure 3 for Figure 2 Hydraulic schematic diagram of a medium-variable pump unit;

[0029] Figure 4 for Figure 1 Hydraulic schematic diagram of the priority valve;

[0030] Figure 5 Hydraulic schematic diagram of the control unit;

[0031] Figure 6 This is a hydraulic schematic diagram of the braking unit;

[0032] [Explanation of Key Component Symbols]

[0033] 1. Energy supply unit

[0034] 101. Oil tank; 102. Variable displacement pump unit

[0035] 103. Priority valve; 104. First check valve

[0036] 105. Priority unloading valve; 106. Accumulator

[0037] 107. Second check valve; 108. First relief valve

[0038] 109. Engine power take-off port; 110. Oil pump

[0039] 111. Swashplate; 112. Load-sensitive proportional valve

[0040] 113. Pressure shut-off valve; 114. Swashplate drive cylinder

[0041] 2. Control Unit

[0042] 201. Slow-down control valve; 202. Loading / unloading / emergency brake valve

[0043] 203. Service brake valve; 204. Pressure gauge

[0044] 205. Parking brake valve; 206. First directional control valve

[0045] 207. Gearbox; 208. First shuttle valve

[0046] 209. Second shuttle valve; 210. Second directional valve

[0047] 3. Braking unit

[0048] 301. Road condition switching valve assembly; 302. Solenoid valve for slippery road surfaces.

[0049] 303, First Relay Valve; 304, Third Shuttle Valve

[0050] 305. Second relay valve; 306. Fourth shuttle valve

[0051] 307. First back pressure valve assembly; 308. Third relay valve

[0052] 309. First full-disc wet brake for the middle bridge; 310. Fifth shuttle valve.

[0053] 311. Second back pressure valve assembly; 312. Rear axle first full disc wet brake.

[0054] 313. Second full disc wet brake on the rear axle; 314. Third back pressure valve assembly.

[0055] 315. Second full-disc wet brake for the middle axle; 316. Adjustable flow valve.

[0056] 317. Fourth back pressure valve assembly; 318. Sixth shuttle valve

[0057] 319. Second relief valve; 320. Front axle first brake.

[0058] 321. Front axle second brake; 322. Retarder cylinder Detailed Implementation

[0059] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of the specific implementation, structure, features and effects of the hydraulic braking system for wide-body mining vehicles proposed according to the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0060] Please see Figure 1The present invention provides a schematic diagram of the composition of the hydraulic braking system for a wide-body mining vehicle. The hydraulic braking system includes a power supply unit 1, a control unit 2, and a braking unit 3.

[0061] The power supply unit 1 includes a variable pump group 102 and an accumulator 106. The variable pump group 102 and the accumulator 106 also function as a control unit 2. The control unit 2 includes a service brake control unit and a parking brake control unit. The variable pump 102 and the accumulator 106 directly function as the parking brake control unit and indirectly supply power to the service brake control unit through a priority valve 103.

[0062] The P port of the priority valve 103 is connected to the variable pump 102 and the accumulator 106. The CF port of the priority valve 103 is connected to the loading / unloading / emergency brake valve 202 and the service brake valve 203. The outlet pipes of the loading / unloading / emergency brake valve 202 and the service brake valve 203 are both connected to the LS port of the priority valve 103. When the loading / unloading / emergency brake valve 202 and the service brake valve 203 are activated, their outlet pressure oil will be fed back to the LS port of the priority valve 103. The oil enters the left end of the priority valve 103 through the LS port. The force on the left side of the valve core is greater than that on the right side. The valve core moves to the right, the CF port increases, and the EF port decreases. When the force on the left side of the valve core is large enough, the EF port decreases and closes completely. All the pressure oil is supplied to the CF port, thereby realizing the distribution of braking energy in the service brake control unit to meet the energy supply requirements of service brake and emergency brake in the event of a sudden failure and ensure driving safety.

[0063] Specifically, during normal vehicle operation, due to the spring force on the left side of the priority valve 103, the priority valve 103 is in the left position, and the P port is initially connected to the CF port. After the high-pressure oil is introduced, it preferentially enters the P port of the loading / unloading / emergency brake valve 202 and the service brake valve 203 of the control unit 2. The valve core of the priority valve 103 is in a certain equilibrium position in the middle under the action of the hydraulic pressure on both sides and the spring force, and the EF port is connected to the P port of the easing control valve 201. When the loading / unloading / emergency brake valve 202 or the service brake valve 203 of the control unit 2 is activated, its outlet pressure oil enters the left end of the priority valve 103 through the LS port of the priority valve 103. The force on the left side of the valve core is greater than that on the right side, the valve core moves to the right, the CF port increases and the EF port decreases, and the high-pressure oil preferentially ensures the needs of service braking and emergency braking.

[0064] If the flow demand of the braking system exceeds the output flow of the variable pump unit 102 and the accumulator 106, or if the power supply component of the braking system fails, the system pressure decreases, and the pressurized oil can no longer meet the full braking strategy. At this time, the hydraulic pressure on the right end of the priority valve 103 spool decreases accordingly. Under the action of the spring force, the balance state of the priority valve 103 spool is broken, the spool moves to the right, the CF port increases, and the EF port decreases. The pressurized oil prioritizes meeting the flow demand of the CF port. High-pressure oil prioritizes ensuring the needs of service braking and emergency braking.

[0065] The variable pump assembly 102 is provided with a first check valve 104 on its outlet pipeline. The first check valve 104 can prevent the pressure oil from flowing back and damaging the variable pump assembly 102 due to excessive pressure in the accumulator 106 or control unit 2.

[0066] A priority unloading valve 105 is also provided between the variable pump assembly 102 and the accumulator 106. This priority unloading valve 105 is used to provide feedback on the oil pressure of the accumulator 106, thereby adjusting the displacement of the oil pump 110 of the variable pump assembly 102. The oil inlet of the priority unloading valve 105 is connected to the oil pump 110, the oil outlet is connected to the oil tank 101, and the spring chamber is connected to the accumulator 106. Furthermore, a feedback oil circuit is formed between the oil inlet of the priority unloading valve 105 and the oil pump displacement control unit of the variable pump assembly 102. When the accumulator 106 is filled with liquid, the oil inlet and outlet of the priority unloading valve 105 are not connected. The oil entering through the oil inlet is fed back to the oil pump displacement control unit of the variable pump assembly 102 through the feedback oil circuit, thereby maximizing the oil pump displacement. When the accumulator 106 is fully charged, the pressure inside the accumulator 106 reaches the upper limit of the pressure set by the priority unloading valve 105. The spring chamber of the priority unloading valve 105 moves, connecting the inlet and outlet, and the priority unloading valve 105 overflows. The feedback oil circuit unloads the pressure to the oil tank 101 through the outlet. The variable pump group 102 loses the feedback signal, and the oil pump displacement control unit rapidly reduces the displacement and pressure of the oil pump 110 to a standby state. When the pressure inside the accumulator 106 drops to the lower limit after multiple braking functions, i.e., reaching the lower limit set by the priority unloading valve 105, the priority unloading valve 105 overflows and closes, disconnecting the inlet and outlet again. The feedback oil circuit feeds back to the oil pump displacement control unit, increasing the displacement of the oil pump 110 and recharging the accumulator. This process repeats to ensure that the pressure inside the accumulator is maintained at the system set value, ensuring that the system has a sufficient power source.

[0067] The oil pump displacement control unit includes a load-sensitive proportional valve 112, a pressure shut-off valve 113, a swashplate drive cylinder 114, and a drive swashplate 111. Feedback from the priority unloading valve 105 sets the load-sensitive proportional valve 112 and pressure shut-off valve 113 to the right position, preventing pressurized oil from entering the swashplate drive cylinder 114. The swashplate 111 remains stationary, and the oil pump 110 operates at maximum displacement. When the feedback from the unloading valve 105 is lost, the pressure on the left side of the load-sensitive proportional valve 112 increases, setting it to the left position. Pressurized oil then enters the swashplate drive cylinder 114 via the load-sensitive proportional valve 112 and pressure shut-off valve 113, driving the swashplate 111 to rotate counterclockwise, rapidly reducing the oil pump 110's displacement and pressure to a standby state. When the feedback oil circuit of the self-priority unloading valve 105 is received again, the load-sensitive proportional valve 112 and the pressure shut-off valve 113 are placed in the right position, the pressure oil in the swashplate drive cylinder 114 returns to the oil tank 101, and the spring in the cylinder causes the swashplate drive cylinder 114 to drive the swashplate 111 to rotate clockwise, and the displacement of the oil pump 110 increases.

[0068] The load-sensitive proportional valve of this invention controls the displacement of the variable pump group by comparing the feedback oil pressure of the priority unloading valve with the oil pump outlet pressure, thereby adjusting the real-time output power of the variable pump group and effectively reducing power waste. When the oil pump 110 outlet pressure is greater than the spring preset pressure of the pressure shut-off valve 113, the valve core of the pressure shut-off valve 405 moves to the right and to the left position. The rodless chamber of the swashplate drive cylinder 114 quickly receives oil, pushing the swashplate 111 to move counterclockwise. The output power of the oil pump 110 gradually decreases until it reaches zero, which can prevent excessive hydraulic pressure from damaging the hydraulic system and protect the system and components.

[0069] The accumulator 106 is also connected to a first overflow valve 108 at its oil outlet. If the pressure at the accumulator outlet is greater than the set pressure value of the first overflow valve 108, the high-pressure oil can return to the oil tank 101 from the first overflow valve 108.

[0070] The service brake control unit of the control unit 2 includes a service brake valve 203, a loading / unloading / emergency brake valve 202, and a slow-down control valve 201. Both the service brake valve 203 and the loading / unloading / emergency brake valve 202 are connected to the road condition switching valve group 301 of the braking unit 3 via a first shuttle valve 208 and a second shuttle valve 209. This road condition switching valve group 301 controls the operation of the first front axle brake 320 and the second front axle brake 321, achieving service braking and loading / unloading / emergency braking for the front axle. The service brake valve 203 and the loading / unloading / emergency brake valve 202 are also connected to the control oil ports L of the second relay valve 305 and the third relay valve 308 via the first shuttle valve 208 and the second shuttle valve 209. By pushing the valve core of the relay valve to the right, the P port of the relay valve communicates with the A port, allowing pressurized oil to enter the B port of the full-disc wet brake of the middle and rear axles, achieving service braking and loading / unloading / emergency braking for the middle and rear axles.

[0071] When the service brake valve 203 is activated, high-pressure oil from the power supply unit 1 enters the road condition switching valve group 301 of the braking unit 3 via the service brake valve 203, the first shuttle valve 208, and the second shuttle valve 209. It then enters the first brake 320 and the second brake 321 of the front axle to achieve front axle service braking. At the same time, the high-pressure oil also enters the control oil port L of the second relay valve 305 and the third relay valve 308, pushing the valve core of the relay valve to the right so that the P port of the relay valve is connected to the A port. The pressurized oil enters the B port of the full disc wet brake of the middle and rear axles to achieve middle and rear axle service braking.

[0072] When the vehicle is in motion, if it encounters an emergency (such as a malfunction of the service brake valve 203) and cannot brake normally, emergency braking can be applied to bring the vehicle to a quick stop. The loading / unloading / emergency brake valve 202 is activated, and high-pressure oil from the power supply unit 1 enters the road condition switching valve group 301 of the braking unit 3 via the loading / unloading / emergency brake valve 202, the first shuttle valve 208, and the second shuttle valve 209. This oil then enters the first brake 320 and the second brake 321 of the front axle to achieve emergency braking of the front axle. Simultaneously, high-pressure oil also enters the control port L of the second relay valve 305 and the third relay valve 308, pushing the relay valve core to the right to connect the relay valve's P port with its A port. Pressure oil then enters the B port of the full-disc wet brake of the middle and rear axles to achieve emergency braking of the middle and rear axles.

[0073] When the vehicle stops and loading / unloading operations are performed, the loading / unloading / emergency brake valve 202 is energized and placed in the upper position. High-pressure oil from the power supply unit 1 enters the road condition switching valve group 301 of the braking unit 3 via the loading / unloading / emergency brake valve 202, the first shuttle valve 208, and the second shuttle valve 209. This oil then enters the first brake 320 and the second brake 321 of the front axle to achieve loading / unloading braking of the front axle. Simultaneously, high-pressure oil enters the control port L of the second relay valve 305 and the third relay valve 308, pushing the valve core of the relay valve to the right, making the P port of the relay valve connected to the A port. The pressurized oil then enters the B port of the full-disc wet brake of the middle and rear axles to achieve loading / unloading braking of the middle and rear axles. Simultaneous loading / unloading braking of all three axles can effectively avoid dangers such as slippage during vehicle loading and unloading operations. At the same time, the high-pressure oil driving the friction lining brake of the middle and rear axles can avoid damage to the parking brake caused by the impact of loading and unloading materials when applying a separate parking brake.

[0074] The retardation control valve 201 controls the retarder cylinder 322 and the full-disc wet brakes of the middle and rear axles via the second reversing valve 210. When the vehicle is going downhill for a long time, the retardation braking is activated, and the retardation control valve 201 is activated to the upper position. High-pressure oil from the power supply unit 1 enters the B port of the full-disc wet brakes of the middle and rear axles of the braking unit 3 through the retardation control valve 201 and the second reversing valve 210, realizing the retardation braking of the middle and rear axles. When the brakes of the middle and rear axles overheat and reach the system set value, the second reversing valve 210 is energized to the upper position, and the high-pressure oil... Oil enters the retarder cylinder 322 of the braking unit 3, thereby controlling the oil flow in and out of the transmission hydraulic retarder to achieve slow braking. When the retarder cylinder 322 heats up too much and reaches the set value, the second reversing valve 210 is de-energized and placed in the lower position. High-pressure oil enters port B of the full disc wet brake of the middle and rear axles of the braking unit 3 to achieve slow braking of the middle and rear axles. In this way, the two slow braking methods are alternated to slow braking, which can increase the service life of the full disc wet brake of the middle and rear axles, improve the consistency of the system braking performance, and effectively ensure the safety of the vehicle when driving downhill.

[0075] The parking brake control unit of control unit 2 includes a parking brake valve 205. A variable displacement pump assembly 102 and an accumulator 106 directly supply pressurized oil to the parking brake valve 205. When the vehicle is parked, the parking brake valve 205 is activated to the lower position, allowing high-pressure oil from port A of the full-disc wet brake on the middle and rear axles in braking unit 3 to return to the oil tank, thus activating the parking brake. After the vehicle starts, the parking brake is closed, and the parking brake valve 205 is closed to the upper position. High-pressure oil then enters port A of the full-disc wet brake on the middle and rear axles through the parking brake valve 205, releasing the parking brake.

[0076] The parking brake control unit also includes a first reversing valve 206 and a transmission 207. The first reversing valve 206 is connected to the lower outlet of the parking brake valve 205. When the parking brake valve 205 is activated and in the lower position, pressurized oil can reach the first reversing valve 206 through the parking brake valve 205. When the vehicle is not started, the pressure inside the transmission 207 increases, causing the first reversing valve 206 to be in the lower position. High-pressure oil from the power supply unit 1 enters the control port L of the service brake valve 203, activating the service brake valve 203 and putting the vehicle into box brake mode. After the vehicle is started, the parking brake is closed, and the parking brake valve 205 is activated and in the upper position. High-pressure oil enters the A port of the full disc wet brake of the middle and rear axle in the braking unit 3, releasing the parking brake. At the same time, the pressure inside the transmission 207 decreases, and the first reversing valve 206 is activated and in the upper position under the action of spring force. The pressurized oil at the control port L of the service brake valve 203 returns to the oil tank, releasing the box brake mode.

[0077] The braking unit 3 includes a retarder cylinder 322, a front axle brake section, a rear axle brake section, and a middle axle brake section; wherein the front axle brake section includes a road condition switching valve group 301, a front axle first brake 320, and a front axle second brake 321, wherein the road condition switching valve group 301 includes a wet road surface solenoid valve 302, a first relay valve 303, and a third shuttle valve 304, wherein the input port P of the wet road surface solenoid valve 302 is connected to the service brake control unit, the output port B of the wet road surface solenoid valve 302 is connected to the inlet B of the third shuttle valve 304, and the output port A is connected to the L port of the first relay valve 303. When the vehicle brakes on a normal road surface, the wet / slippery road surface solenoid valve 302 is in the lower position. High-pressure oil supplied by the service brake control unit enters the front axle first brake 320 and front axle second brake 321 through the input port P and output port B of the wet / slippery road surface solenoid valve 302, and the inlet B and outlet P of the third shuttle valve 304, thus achieving front axle braking. When encountering a wet / slippery road surface, the wet / slippery road surface solenoid valve 302 is in the upper position. High-pressure oil enters the L port of the first relay valve 303, reducing the front axle braking pressure. The opening degree of the first relay valve 303 is proportional to the stroke of the service brake valve 203, improving driver comfort and vehicle safety. The P port of the first relay valve 303 is always connected to the accumulator 106 in the power supply unit 1 to shorten the braking response time.

[0078] The braking system of the middle bridge includes a second relay valve 305, a fourth shuttle valve 306, a first back pressure valve group 307, a first full-disc wet brake 309 for the middle bridge, a fourth back pressure valve group 317, and a second full-disc wet brake 315 for the middle bridge.

[0079] The rear axle braking system includes a third relay valve 308, a fifth shuttle valve 310, a second back pressure valve group 311, a first full disc wet brake for the rear axle 312, a second full disc wet brake for the rear axle 313, and a third back pressure valve group 314.

[0080] The middle axle braking section and the rear axle braking section are connected to the control unit 2 via the L port of the second relay valve 305 and the third relay valve 308, respectively. The second relay valve 305 and the third relay valve 308 are installed near the axle, and their P ports are always connected to the accumulator 106 in the power supply unit 1, which can shorten the braking response time and make the braking more sensitive.

[0081] The fourth back pressure valve group 317 consists of an adjustable flow valve 316, a sixth shuttle valve 318, and a second overflow valve 319. It releases the parking brake pressure oil, which simultaneously enters port A of the full disc wet brake via the adjustable flow valve 316 and the sixth shuttle valve 318, thus shortening the distance between the dynamic and static friction pads used for service braking within the full disc wet brake, making the vehicle more responsive when applying the service brake. If the high-pressure oil entering the fourth back pressure valve group 317 is too high, the second overflow valve 319 overflows the high-pressure oil back to the oil tank 101. The first back pressure valve group 307, the second back pressure valve group 311, and the third back pressure valve group 314 operate on the same principle as the fourth back pressure valve group 317. The adjustable flow valve and overflow valve in the back pressure valve group of this invention prevent the full disc wet brake from locking due to excessive pressure at port B.

[0082] The first full-disc wet brake 309 of the middle axle, the first full-disc wet brake 312 of the rear axle, the second full-disc wet brake 313 of the rear axle, and the second full-disc wet brake 315 of the middle axle operate on the same principle, integrating service braking and parking braking into one unit. During service braking, pressurized oil is introduced through port B of the full-disc wet brake, overcoming the return spring force within the service brake chamber, causing the moving friction pads to press against the stationary friction pads to generate braking force, thus implementing service braking. Specifically, during service braking, pressurized oil enters port B of the full-disc wet brake through the shuttle valve of the back pressure valve assembly. During parking braking, system pressurized oil returns to the oil tank 101 from port A of the full-disc wet brake, and the spring within the parking brake chamber causes the moving friction pads to press against the stationary friction pads to generate braking force, thus implementing parking braking.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A hydraulic braking system for a wide-body mining vehicle, comprising a power supply unit, a control unit, and a braking unit, wherein the control unit includes a parking brake control unit and a service brake control unit, characterized in that: The power supply unit directly supplies pressurized oil to the parking brake control unit and supplies pressurized oil to the service brake control unit through the priority valve. The service brake control unit includes a service brake valve, a loading / unloading / emergency brake valve, and a retardation control valve. The power supply unit is connected to the P port of the priority valve, the service brake valve and the loading / unloading / emergency brake valve are connected to the CF port of the priority valve, and the P port of the retardation control valve is connected to the EF port of the priority valve. The outlet pipes of the service brake valve and the loading / unloading / emergency brake valve are both connected to the LS port of the priority valve. This ensures that when the service brake valve and the loading / unloading / emergency brake valve are activated, their outlet pressurized oil is fed back to the LS port of the priority valve, causing the CF port to increase and the EF port to decrease. The braking unit includes a front axle braking section, a middle and rear axle braking section, and a retarder cylinder. The retarder control valve controls the full-disc wet brakes of the retarder cylinder and the middle and rear axle retarder braking section through a second reversing valve, and switches between retarder cylinder retarder braking and middle and rear axle retarder braking through the second reversing valve.

2. The hydraulic braking system for wide-body mining vehicles according to claim 1, characterized in that: When the brake temperature of either the retarder cylinder brake or the middle and rear axle retarder brake reaches a set value, the brake will switch to the other brake.

3. The hydraulic braking system for wide-body mining vehicles according to claim 2, characterized in that: The front axle braking system includes a road condition switching valve assembly and a front axle brake. The road condition switching valve assembly includes a wet / slippery road surface solenoid valve, a first relay valve, and a third shuttle valve. The input port P of the wet / slippery road surface solenoid valve is connected to the service brake valve and the loading / unloading / emergency brake valve. The output port A is connected to the L port of the first relay valve, and the output port B is connected to the inlet B of the third shuttle valve. The inlet A of the third shuttle valve is connected to the A port of the first relay valve, and the P port of the first relay valve is connected to the power supply unit. The outlet P of the third shuttle valve is connected to the front axle brake.

4. The hydraulic braking system for wide-body mining vehicles according to claim 3, characterized in that: The middle and rear axle braking system includes a middle axle braking system and a rear axle braking system. Both the middle and rear axle braking systems include a relay valve, a back pressure valve assembly, and a full-disc wet brake. The L port of the relay valve is connected to the service brake valve and the loading / unloading / emergency brake valve, the P port is connected to the power supply unit, and the A port is connected to the back pressure valve assembly. The back pressure valve assembly includes an adjustable flow valve, a shuttle valve, and an overflow valve. The inlet A of the shuttle valve is connected to the A port of the relay valve, the inlet B is connected to the A port of the full-disc wet brake through the adjustable flow valve, the outlet P is connected to the B port of the full-disc wet brake, and the overflow valve is located between the inlet B of the shuttle valve and the adjustable flow valve.

5. The hydraulic braking system for wide-body mining vehicles according to claim 4, characterized in that: The parking brake control unit includes a parking brake valve, which is connected to the A port of the full disc wet brake of the middle axle braking part and the rear axle braking part. When the parking brake valve is in the lower position, it also supplies pressurized oil to the control port L of the service brake valve through the first reversing valve, so as to start the service brake valve.

6. The hydraulic braking system for wide-body mining vehicles according to claim 1, characterized in that: The power supply unit includes a variable pump group and an accumulator. A priority unloading valve is also provided between the variable pump group and the accumulator. When the pressure in the accumulator is lower than the set value, the priority unloading valve can connect the oil circuit with the feedback of the variable pump group to increase the pump displacement of the variable pump group. When the pressure in the accumulator reaches the set pressure, the valve can disconnect the oil circuit with the feedback of the variable pump group to reduce the pump displacement of the variable pump group.

7. A control method for the hydraulic braking system of a wide-body mining vehicle as described in claim 5, characterized in that: When the system experiences insufficient pressure oil or an emergency requiring service braking or emergency braking during slow braking, the service brake valve or loading / unloading / emergency brake valve is activated. Pressure oil from the power supply unit flows through the P port of the priority valve to the CF and EF ports. Pressure oil at the outlet of the service brake valve or loading / unloading / emergency brake valve is fed back to the LS port of the priority valve, causing the valve core of the priority valve to move towards the EF port. This increases the CF port and decreases the EF port, increasing the pressure oil supplied to the service brake valve or loading / unloading / emergency brake valve and decreasing the oil supply to the slow control valve. When the pressure feedback from the LS port is sufficiently high, the EF port is completely closed, and all pressure oil is supplied to the service brake valve or loading / unloading / emergency brake valve through the CF port.

8. The control method for the hydraulic braking system of a wide-body mining car according to claim 7, characterized in that: When the vehicle is braking on a normal road surface or in an emergency, the wet / slippery road surface solenoid valve of the road condition switching valve group is in the lower position. The pressure oil from the power supply unit passes through the wet / slippery road surface solenoid valve and the third shuttle valve in sequence to enter the brake to achieve front axle braking. When the vehicle is braking on a wet / slippery road surface or in an emergency, the wet / slippery road surface solenoid valve of the road condition switching valve group is in the upper position. The pressure oil from the power supply unit passes through the wet / slippery road surface solenoid valve to enter the L port of the first relay valve. The pressure of the front axle braking is reduced by the first relay valve. The opening of the first relay valve is adjusted by adjusting the stroke of the service brake valve.

9. The control method for the hydraulic braking system of a wide-body mining car according to claim 7, characterized in that: When the vehicle is under service braking or loading / unloading / emergency braking, the pressurized oil from the power supply unit enters the back pressure assembly of the middle and rear axle braking sections via the relay valve, and then enters port B of the full disc wet brake through the shuttle valve in the back pressure assembly to achieve braking of the middle and rear axles. When the vehicle is under slow braking, the pressurized oil from the power supply unit enters the back pressure assembly of the middle and rear axle braking sections via the slow control valve and the lower position of the second reversing valve, and then enters port B of the full disc wet brake through the shuttle valve in the back pressure assembly to achieve slow braking of the middle and rear axles. Alternatively, if the second reversing valve is in the upper position, the pressurized oil enters the slow braking cylinder to achieve slow braking. When the vehicle is under parking brake, the pressurized oil at port A of the full disc wet brake returns to the oil tank.

Images