Load-sensitive mining dump truck braking system and using method

Abstract

The invention provides a load-sensitive mining dump truck braking system and a using method, and belongs to the technical field of engineering vehicle braking, and the load-sensitive mining dump truck braking system comprises a load-sensitive hydraulic control unit and a braking execution unit. The load-sensitive system compares the output pressure of the power source with the actual brake demand pressure in real time through a pressure detection and feedback mechanism, and automatically adjusts the displacement of the hydraulic pump according to the output pressure, so that the output pressure of the brake system of the load-sensitive mining dump truck is dynamically matched with the brake demand; the braking system comprises a service braking loop and an independent parking braking loop, and switching and control of braking states are achieved through operation of a driver. The system automatically enters a low-pressure energy-saving mode in a non-braking state, on-demand pressure supply is achieved in the braking process, the technical problems that due to continuous high-pressure oil supply of a traditional mine car braking system, energy consumption is too high, the oil temperature rises fast, and the system efficiency is low are fundamentally solved, and the remarkable energy-saving, consumption-reducing and heat control effects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of engineering vehicle braking technology, and relates to a load-sensitive mining dump truck braking system and its usage method, particularly a mining dump truck braking system and its usage method based on load-sensitive hydraulic control technology. Background Technology

[0002] In the technical field of braking systems for mining dump trucks, traditional solutions often employ a hydraulic constant-pressure oil supply or a structural design combining a fixed-displacement pump and an overflow valve. To ensure braking response speed and maximum braking force, such systems typically maintain a constant high pressure output from the hydraulic power unit. This results in the system maintaining a high-pressure state even during prolonged driving, standby, or low braking demand conditions, causing a significant amount of hydraulic energy to be converted into heat energy loss through overflow or throttling. This not only leads to significant energy waste but also causes a sharp rise in hydraulic oil temperature, accelerating the aging of seals and the performance degradation of hydraulic components, severely impacting system reliability and service life. Furthermore, the fixed-pressure supply mode makes it difficult to dynamically adjust the output according to actual working conditions, resulting in poor system adaptability and low overall energy efficiency.

[0003] Existing related technologies also suffer from the aforementioned key defects: For example, the air-jacking hydraulic braking system for mining dump trucks disclosed in patent CN207128878U achieves braking control through the cooperation of an air compressor, air tank, relay valve, and booster assembly. Although this simplifies the pipeline layout, it uses a fixed air pressure to drive the hydraulic brake, and the braking force output is a preset threshold. It cannot be dynamically adjusted according to the vehicle's real-time load and speed. Under heavy loads, it is prone to insufficient braking force, and under light loads, it is prone to braking shock. Furthermore, it requires maintaining high pressure in the air circuit during non-braking conditions, resulting in continuous leakage and energy loss. The article "Improvement of Braking System for Trackless Rubber-Tired Mining Trucks" (Shandong Coal Technology, 2015) confirms through field fault statistics and principle analysis that mining vehicle braking systems generally suffer from delayed braking force response and poor adaptability to load changes. The proposed measures, such as optimizing the spring reset structure and improving the filtration system, can only partially alleviate the faults and cannot fundamentally achieve precise matching between load and braking force. The article "Anti-lockbraking system control algorithm for driverless mining dump truck based on fuzzy PID" (Sage (Journals, 2024) designed an anti-lock braking control algorithm based on fuzzy PID for unmanned mining dump trucks. Although it improved the stability during emergency braking, the braking system still relied on the traditional constant pressure supply scheme and did not optimize the oil supply logic. Excess oil flowed back through the overflow valve, resulting in a large amount of energy waste. In addition, the hydraulic oil temperature rose significantly, increasing the load on the cooling system and the risk of component wear.

[0004] Therefore, there is an urgent need for an intelligent braking system that can automatically adjust the output pressure according to actual braking needs and achieve on-demand energy distribution in order to solve key technical defects such as high energy consumption, high heat generation, and low efficiency. Summary of the Invention

[0005] This invention aims to overcome the technical defects of existing braking systems for mining dump trucks. Traditional systems, to ensure the immediacy and reliability of braking, typically employ a constant-pressure oil supply mode in their hydraulic power units. This results in the system maintaining a near-maximum operating pressure even during prolonged non-braking driving or under low braking demand conditions, leading to continuous overflow and throttling losses, resulting in low energy efficiency and excessive operating energy consumption. The resulting significant hydraulic oil temperature rise and severe system overheating not only accelerate the aging of the oil and seals, reducing component reliability and lifespan, but also additionally increase the load on the cooling system. Furthermore, constant-pressure systems struggle to achieve precise and dynamic pressure matching based on actual braking load and pedal opening, resulting in poor system adaptability and energy efficiency. Therefore, this invention provides a load-sensitive braking system for mining dump trucks and its usage method, fundamentally reducing energy consumption and heat load while ensuring braking performance and safety, and improving the overall system efficiency and adaptability.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A load-sensitive braking system for mining dump trucks includes a load-sensing system and a braking system. The load-sensing hydraulic control unit, through a pressure detection and feedback mechanism, compares the output pressure of the power source with the actual braking demand pressure in real time, and automatically adjusts the displacement of the hydraulic pump accordingly, so that the output pressure of the load-sensing mining dump truck braking system dynamically matches the braking demand. The braking execution unit includes a service brake circuit and an independent parking brake circuit, and the switching and control of the braking state are achieved through driver operation.

[0008] The load-sensitive system includes a motor 1, a variable displacement pump 2, a hydraulic cylinder 3, a variable displacement cylinder 4, a load-sensitive valve 5, a pressure compensation valve 6, and an oil tank 7. The motor 1 connects to and drives the variable displacement pump 2; the hydraulic cylinder 3 cooperates with the variable displacement cylinder 4 to adjust the output displacement and pressure of the variable displacement pump 2; the load-sensitive valve 5 detects the output pressure of the variable displacement pump 2 and the pressure required by the braking system, and adjusts the control pressure of the variable displacement cylinder 4 according to the difference between the two; the pressure compensation valve 6 provides stable pressure compensation in the system, ensuring the control accuracy of the load-sensitive valve 5.

[0009] The braking system mainly includes a first one-way valve 8, a second one-way valve 9, a third one-way valve 10, a first reversing valve 11, a second reversing valve 12, a brake pedal 13, a front axle brake 14, a shuttle valve 15, a rear axle brake 16, a fourth one-way valve 17, a third reversing valve 18, a parking brake 19, a first accumulator 20, a second accumulator 21, and a third accumulator 22. The brake pedal 13 is linked to the valve cores of the first reversing valve 11 and the second reversing valve 12 via a mechanical transmission mechanism. Its pedal travel corresponds linearly to the valve core displacement, achieving synchronous control of the working positions of the two reversing valves. The first reversing valve 11 is a three-position three-way reversing valve. Its inlet port P1 is connected to the outlet pipe of the second one-way valve 9, its outlet port A1 is fixedly connected to the inlet port of the front axle brake 14, and its return port T1 is connected to the oil tank 7. It is responsible for controlling the on / off state and pressure transmission of the front axle braking circuit. The second directional valve 12 is also a three-position three-way directional valve. Its inlet P2 is connected to the outlet of the third check valve 10, its outlet A2 is connected to the first inlet of the shuttle valve 15, and its return port T2 is connected to the oil tank 7. The outlet of the shuttle valve 15 is fixedly connected to the inlet of the rear axle brake 16. An expansion interface is reserved at the second inlet to accommodate multi-axle braking systems. The third directional valve 18 is a two-position three-way directional valve. Its inlet P3 is connected to the outlet of the fourth check valve 17, its outlet A3 is fixedly connected to the inlet of the parking brake 19, and its return port T3 is connected to the oil tank 7, thus enabling independent on / off control of the parking brake circuit. The third accumulator 22 is connected in parallel between the oil inlet of the front axle brake 14 and the oil outlet A1 of the first directional valve 11 via a branch pipeline. The second accumulator 21 is connected in parallel between the oil inlet of the rear axle brake 16 and the oil outlet of the shuttle valve 15. The first accumulator 20 is connected in parallel between the oil inlet of the parking brake 19 and the oil outlet A3 of the third directional valve 18. All three are sealed to the corresponding circuits through pressure interfaces.

[0010] Furthermore, in the load-sensitive system, the load-sensitive valve 5 compares the output pressure of the variable pump 2 with the brake's required pressure in real time, and automatically adjusts the displacement of the variable pump 2 accordingly to achieve adaptive control of the output pressure. When the system pressure is higher than the set value, the load-sensitive valve 5 switches to the first operating position, and the pressure oil drives the variable cylinder 4 to reduce the displacement of the variable pump 2 to lower the pressure; when the braking demand is higher than the pump's output pressure, the load-sensitive valve 5 switches to the second operating position, and the spring of the cylinder 3 pushes the variable pump 2 to increase the displacement to increase the pressure. This system, through closed-loop regulation, always dynamically matches the output pressure with the braking demand, achieving on-demand pressure supply.

[0011] Furthermore, the inlet of the first check valve 8 in the braking system is connected to the outlet of the variable pump 2 in the load-sensitive system through the main oil supply pipe, forming the main oil inlet channel of the braking system. Its outlet is connected to the inlet of the second check valve 9, the third check valve 10, and the fourth check valve 17 through branch pipes, respectively, to realize parallel oil supply to the service brake circuit (front axle and rear axle) and the parking brake circuit. The first check valve 8, the second check valve 9, the third check valve 10, and the fourth check valve 17 are all installed in a forward conduction and reverse cut-off direction, respectively connected in series in each branch oil supply circuit, which can prevent the hydraulic oil of each brake circuit from flowing back in reverse, avoid pressure interference between circuits, and ensure that the pressure of each circuit is independent and stable.

[0012] Furthermore, the first reversing valve 11 and the second reversing valve 12 in the braking system are each provided with a position 1 (non-braking position), a position 2 (pressure build-up preparation position), and a position 3 (braking working position). In position 1, the oil inlet port P1 / P2 is closed, and the oil return port T1 / T2 and the oil outlet port A1 / A2 are connected, realizing the brake pressure relief and oil return. In position 2, the oil return port T1 / T2 is closed, and both the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are closed, preparing for brake pressure build-up. In position 3, the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are connected, and the oil return port T1 / T2 is closed, realizing the delivery of pressurized oil to the brake. The third directional valve 18 has a 1-position (parking brake position) and a 2-position (parking release position). In position 1, the oil inlet P3 and oil outlet A3 are connected, and the oil return port T3 is closed, allowing pressurized oil to enter the parking brake 19 to lock it. In position 2, the oil outlet A3 and oil return port T3 are connected, and the oil inlet P3 is closed, allowing hydraulic oil in the parking brake 19 to flow back and unlock it. The shuttle valve 15 can automatically identify and connect the side with higher pressure between the first and second oil inlets to ensure that the rear axle brake 16 obtains a stable maximum braking pressure and avoids brake failure. The first accumulator 20, the second accumulator 21, and the third accumulator 22 are all bladder-type, which have pressure buffering, pressure compensation, and emergency backup functions, improving braking smoothness, maintaining pressure stability, and ensuring emergency braking needs. The front axle brake 14 and the rear axle brake 16 are hydraulic caliper disc brakes, which generate braking torque through hydraulic drive to decelerate or stop the vehicle; the parking brake 19 is a hydraulically driven mechanical locking type, which engages with the wheel hub through a locking mechanism to fix the vehicle in place and prevent it from rolling away.

[0013] Furthermore, the driver controls the operating positions of the first reversing valve 11 and the second reversing valve 12 by operating the brake pedal 13, thereby switching the braking system between non-braking and braking states. Further description follows:

[0014] When the brake pedal 13 is not depressed, both the first directional valve 11 and the second directional valve 12 are in the initial 1-position working state. At this time, the pressure oil circuit from the load-sensitive system is cut off, and both the front axle brake 14 and the rear axle brake 16 are in the released state. The hydraulic oil inside them returns directly to the oil tank 7 through the circuit.

[0015] When the driver depresses the brake pedal 13, the first directional valve 11 and the second directional valve 12 first switch to the 2-position working state. This position cuts off the return oil passage between the front axle brake 14 and the rear axle brake 16, preparing for brake pressure build-up. As the brake pedal 13 is further depressed, the first directional valve 11 and the second directional valve 12 further switch to the 3-position working state. At this time, hydraulic oil from the load-sensitive system enters the front axle brake 14 sequentially through the first check valve 8, the second check valve 9, and the first directional valve 11; simultaneously, the pressurized oil also enters the rear axle brake 16 through the first check valve 8, the third check valve 10, the second directional valve 12, and the shuttle valve 15, thereby putting both the front and rear axle brakes into braking mode.

[0016] Furthermore, the first accumulator 20, the second accumulator 21, and the third accumulator 22 in the braking system are respectively used to provide pressure buffering and stabilization for the parking brake 19, the rear axle brake 16, and the front axle brake 14. When the vehicle needs to be parked, the third directional valve 18 switches to the first position, and hydraulic oil enters the parking brake 19 to realize the parking brake function.

[0017] A method for using a load-sensitive braking system for a mining dump truck, capable of automatically adjusting output pressure, includes the following steps:

[0018] Step 1: System initial standby (start-up from non-braking state);

[0019] When the vehicle is not braking, the brake pedal 13 is not depressed, and both the first reversing valve 11 and the second reversing valve 12 remain in their initial position 1. At this time, the motor 1 in the load-sensitive system drives the variable pump 2 to operate. The variable pump 2 draws hydraulic oil from the oil tank 7 and outputs it. Since the first reversing valve 11 and the second reversing valve 12 are in position 1, the hydraulic oil cannot enter the braking circuits corresponding to the front axle brake 14 and the rear axle brake 16 through the two reversing valves, and the braking circuit is in an open circuit state.

[0020] Step 2: Adaptive pressure adjustment in non-braking state;

[0021] The hydraulic oil continuously output by the variable pump 2 in step 1 gradually increases due to the brake circuit being disconnected. When the system pressure rises to the preset pressure threshold of the load-sensitive valve 5, the pressure pushes the valve core of the load-sensitive valve 5 to move to the right against the internal spring force, causing the load-sensitive valve 5 to switch to the 1st position working state. Subsequently, the hydraulic oil flows into the variable cylinder 4 through the load-sensitive valve 5 and the pressure compensation valve 6 in sequence, pushing the piston of the variable cylinder 4 to move to the left. The piston of the variable cylinder 4 drives the swashplate of the variable pump 2 to reduce its tilt angle through a mechanical connection, thereby reducing the output displacement of the variable pump 2. As the displacement of the variable pump 2 decreases, the system output pressure decreases synchronously until the variable pump 2 stabilizes at the minimum displacement state. At this time, the output power and output pressure of the variable pump 2 are at their lowest, and the system energy consumption and heat generation are reduced to the lowest level. At the same time, the piston of the cylinder 3 moves to the right under the action of the system pressure and remains in a compressed state, completing the low-pressure energy-saving regulation in the non-braking state.

[0022] Step 3: Braking and boosting preparation;

[0023] When the driver presses the brake pedal 13, the brake pedal 13 drives the first reversing valve 11 and the second reversing valve 12 to switch to the 3-position working state simultaneously through the mechanical transmission mechanism, the brake circuit is connected, and the front axle brake 14 and the rear axle brake 16 enter the braking preparation state; one end of the load sensitive valve 5 detects the output pressure of the variable pump 2 in real time, and the other end detects the required braking pressure of the front axle brake 14 and the rear axle brake 16 through the feedback pipeline, forming a pressure comparison.

[0024] Step 4: Brake boost adjustment (when output pressure is insufficient);

[0025] For the two sets of pressures detected by the load-sensitive valve 5 in step 3, if the output pressure of the variable pump 2 is lower than the braking pressure required by the front axle brake 14 and the rear axle brake 16, the load-sensitive valve 5 remains in position 2 under the action of its internal spring. At this time, the spring in the cylinder 3, which is in a compressed state, releases its elastic force, pushing the piston of the cylinder 3 to move to the left. The piston of the cylinder 3 drives the swashplate angle of the variable pump 2 to increase through mechanical connection, thereby increasing the output pressure of the variable pump 2. During this process, the piston of the variable cylinder 4 moves to the right under mechanical linkage, and the hydraulic oil in its cavity flows back to the oil tank 7 through the pressure compensation valve 6 and the load-sensitive valve 5. The swashplate angle of the variable pump 2 is continuously increased until the output pressure of the variable pump 2 reaches the braking pressure level required by the front axle brake 14 and the rear axle brake 16, completing the brake boosting stage.

[0026] Step 5: Braking pressure stabilization adjustment (when output pressure is excessive);

[0027] For the system that reaches the braking pressure requirement in step 4, if the variable pump 2 continues to output, causing the system pressure to continue to rise and exceed the preset pressure threshold of the load-sensitive valve 5, the excess pressure will push the valve core of the load-sensitive valve 5 to move to the right again, causing the load-sensitive valve 5 to switch to the 1st position working state. Subsequently, the hydraulic oil flows through the load-sensitive valve 5 and the pressure compensation valve 6 into the variable cylinder 4, pushing the piston of the variable cylinder 4 to move to the left. The piston of the variable cylinder 4 drives the swashplate angle of the variable pump 2 to decrease through a mechanical connection, thereby reducing the output displacement of the variable pump 2. As the displacement of the variable pump 2 decreases, the system output pressure decreases synchronously until it precisely matches the braking pressure required by the front axle brake 14 and the rear axle brake 16, maintaining the stability of the braking process.

[0028] Step 6: Braking ends and system reset;

[0029] When the driver releases the brake pedal 13, the first reversing valve 11 and the second reversing valve 12 switch back to the 1st position working state under the action of the reset mechanism, the brake circuit is disconnected, and the hydraulic oil in the front axle brake 14 and the rear axle brake 16 flows back to the oil tank 7 through the circuit, and the brakes are released; at the same time, the system pressure gradually decreases, the load sensitive valve 5 is reset under the action of the internal spring force, the piston of the variable cylinder 4 moves to the right, the piston of the oil cylinder 3 pushes the swashplate tilt angle of the variable pump 2 to return to the initial state, and the system returns to the initial standby state of step 1, waiting for the next braking operation.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) This invention integrates load-sensitive hydraulic control technology into the braking system of mining dump trucks, realizing the transformation from continuous high-pressure supply to dynamic adjustment on demand, thereby bringing multiple significant benefits: the energy-saving effect is extremely significant. In the non-braking state, the variable pump can automatically maintain the minimum displacement low-pressure standby, with extremely low energy consumption. During the braking process, the output pressure can match the brake demand in real time and accurately, avoiding the continuous overflow loss caused by constant high-pressure supply in traditional systems. This can greatly reduce the no-load and throttling energy consumption of the hydraulic system, and directly reduce fuel or electricity consumption.

[0032] (2) The heat generation of the load-sensitive mining dump truck braking system designed in this invention can be fundamentally controlled. Due to the significant reduction in energy waste, the hydraulic oil temperature rise is significantly reduced. This not only delays oil aging and improves system reliability, but also reduces dependence on the cooling system and failure rate. It is particularly suitable for long-term, high-load mining conditions.

[0033] (3) The load-sensitive mining dump truck braking system designed in this invention improves both the smoothness and safety of operation. The load-sensitive mechanism ensures the instantaneous response and precise tracking of braking pressure, making the braking feel more linear and controllable, ensuring the reliability of braking and parking safety, and effectively reducing the wear and fatigue of key components such as pumps and valves, extending the service life of the whole vehicle braking system, and reducing maintenance frequency and cost.

[0034] In summary, this invention enables the system to automatically enter a low-pressure energy-saving mode when not braking, and to supply pressure on demand during braking. This fundamentally solves the technical problems of excessive energy consumption, rapid oil temperature rise, and low system efficiency caused by continuous high-pressure oil supply in traditional mining truck braking systems, and has significant energy-saving, consumption-reducing, and thermal control effects. Attached Figure Description

[0035] Figure 1 A schematic diagram of the structure of this invention;

[0036] In the diagram: 1. Motor, 2. Variable pump, 3. Hydraulic cylinder, 4. Variable cylinder, 5. Load-sensitive valve, 6. Pressure compensation valve, 7. Oil tank, 8. First check valve, 9. Second check valve, 10. Third check valve, 11. First directional valve, 12. Second directional valve, 13. Brake pedal, 14. Front axle brake, 15. Shuttle valve, 16. Rear axle brake, 17. Fourth check valve, 18. Third directional valve, 19. Parking brake, 20. First accumulator, 21. Second accumulator, 22. Third accumulator. Detailed Implementation

[0037] The present invention will be further described below with reference to specific implementation examples.

[0038] A load-sensitive braking system for mining dump trucks includes a load-sensing system and a braking system. The load-sensing hydraulic control unit, through a pressure detection and feedback mechanism, compares the output pressure of the power source with the actual braking demand pressure in real time, and automatically adjusts the displacement of the hydraulic pump accordingly, so that the output pressure of the load-sensing mining dump truck braking system dynamically matches the braking demand. The braking execution unit includes a service brake circuit and an independent parking brake circuit, and the switching and control of the braking state are achieved through driver operation.

[0039] The load-sensitive system includes a motor 1, a variable displacement pump 2, a hydraulic cylinder 3, a variable displacement cylinder 4, a load-sensitive valve 5, a pressure compensation valve 6, and an oil tank 7. The motor 1 connects to and drives the variable displacement pump 2; the hydraulic cylinder 3 cooperates with the variable displacement cylinder 4 to adjust the output displacement and pressure of the variable displacement pump 2; the load-sensitive valve 5 detects the output pressure of the variable displacement pump 2 and the pressure required by the braking system, and adjusts the control pressure of the variable displacement cylinder 4 according to the difference; the pressure compensation valve 6 provides stable pressure compensation in the system, ensuring the control accuracy of the load-sensitive valve 5. In this embodiment, the load-sensitive valve 5 compares the output pressure of the variable displacement pump 2 with the brake's required pressure in real time, and automatically adjusts the displacement of the variable displacement pump 2 accordingly, achieving adaptive control of the output pressure. When the system pressure is higher than the set value, the load-sensitive valve 5 switches to the first operating position, and the pressurized oil drives the variable displacement cylinder 4 to reduce the displacement of the variable displacement pump 2 to lower the pressure; when the braking demand is higher than the pump's output pressure, the load-sensitive valve 5 switches to the second operating position, and the spring of the hydraulic cylinder 3 pushes the variable displacement pump 2 to increase the pressure. The system uses closed-loop regulation to ensure that the output pressure dynamically matches the braking demand, thus achieving on-demand pressure supply.

[0040] The braking system mainly includes a first one-way valve 8, a second one-way valve 9, a third one-way valve 10, a first reversing valve 11, a second reversing valve 12, a brake pedal 13, a front axle brake 14, a shuttle valve 15, a rear axle brake 16, a fourth one-way valve 17, a third reversing valve 18, a parking brake 19, a first accumulator 20, a second accumulator 21, and a third accumulator 22. The brake pedal 13 is linked to the valve cores of the first reversing valve 11 and the second reversing valve 12 via a mechanical transmission mechanism. Its pedal travel corresponds linearly to the valve core displacement, achieving synchronous control of the working positions of the two reversing valves. The first reversing valve 11 is a three-position three-way reversing valve. Its inlet port P1 is connected to the outlet pipe of the second one-way valve 9, its outlet port A1 is fixedly connected to the inlet port of the front axle brake 14, and its return port T1 is connected to the oil tank 7. It is responsible for controlling the on / off state and pressure transmission of the front axle braking circuit. The second directional valve 12 is also a three-position three-way directional valve. Its inlet P2 is connected to the outlet of the third check valve 10, its outlet A2 is connected to the first inlet of the shuttle valve 15, and its return port T2 is connected to the oil tank 7. The outlet of the shuttle valve 15 is fixedly connected to the inlet of the rear axle brake 16. An expansion interface is reserved at the second inlet to accommodate multi-axle braking systems. The third directional valve 18 is a two-position three-way directional valve. Its inlet P3 is connected to the outlet of the fourth check valve 17, its outlet A3 is fixedly connected to the inlet of the parking brake 19, and its return port T3 is connected to the oil tank 7, thus enabling independent on / off control of the parking brake circuit. The third accumulator 22 is connected in parallel via a branch pipeline between the oil inlet of the front axle brake 14 and the oil outlet A1 of the first directional valve 11. The second accumulator 21 is connected in parallel between the oil inlet of the rear axle brake 16 and the oil outlet of the shuttle valve 15. The first accumulator 20 is connected in parallel between the oil inlet of the parking brake 19 and the oil outlet A3 of the third directional valve 18. All three are sealed to their respective circuits via pressure interfaces.

[0041] In this embodiment, the oil inlet of the first check valve 8 is connected to the oil outlet of the variable pump 2 in the load-sensitive system through the main oil supply pipe, forming the main oil inlet channel of the braking system. Its oil outlet is connected to the oil inlets of the second check valve 9, the third check valve 10, and the fourth check valve 17 through branch pipes, respectively, to realize parallel oil supply to the service brake circuit (front axle and rear axle) and the parking brake circuit. The first check valve 8, the second check valve 9, the third check valve 10, and the fourth check valve 17 are all installed in a forward conduction and reverse cut-off direction, respectively connected in series in each branch oil supply circuit, which can prevent the hydraulic oil of each brake circuit from flowing back in reverse, avoid pressure interference between circuits, and ensure that the pressure of each circuit is independent and stable.

[0042] In this embodiment, both the first reversing valve 11 and the second reversing valve 12 are provided with position 1 (non-braking position), position 2 (pressure build-up preparation position), and position 3 (braking working position). When in position 1, the oil inlet port P1 / P2 is closed, and the oil return port T1 / T2 and the oil outlet port A1 / A2 are connected, realizing the brake pressure relief and oil return. When in position 2, the oil return port T1 / T2 is closed, and both the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are closed, preparing for brake pressure build-up. When in position 3, the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are connected, and the oil return port T1 / T2 is closed, realizing the delivery of pressurized oil to the brake. The third directional valve 18 has a 1-position (parking brake position) and a 2-position (parking release position). In position 1, the oil inlet P3 and oil outlet A3 are connected, and the oil return port T3 is closed, allowing pressurized oil to enter the parking brake 19 to lock it. In position 2, the oil outlet A3 and oil return port T3 are connected, and the oil inlet P3 is closed, allowing hydraulic oil in the parking brake 19 to flow back and unlock it. The shuttle valve 15 can automatically identify and connect the side with higher pressure between the first and second oil inlets to ensure that the rear axle brake 16 obtains a stable maximum braking pressure and avoids brake failure. The first accumulator 20, the second accumulator 21, and the third accumulator 22 are all bladder-type, which have pressure buffering, pressure compensation, and emergency backup functions, improving braking smoothness, maintaining pressure stability, and ensuring emergency braking needs. The front axle brake 14 and the rear axle brake 16 are hydraulic caliper disc brakes, which generate braking torque through hydraulic drive to decelerate or stop the vehicle; the parking brake 19 is a hydraulically driven mechanical locking type, which engages with the wheel hub through a locking mechanism to fix the vehicle in place and prevent it from rolling away.

[0043] In this embodiment, the driver controls the operating positions of the first reversing valve 11 and the second reversing valve 12 by operating the brake pedal 13, thereby switching the braking system between non-braking and braking states. Specifically:

[0044] When the brake pedal 13 is not depressed, both the first directional valve 11 and the second directional valve 12 are in the initial 1-position working state. At this time, the pressure oil circuit from the load-sensitive system is cut off, and both the front axle brake 14 and the rear axle brake 16 are in the released state. The hydraulic oil inside them returns directly to the oil tank 7 through the circuit.

[0045] When the driver depresses the brake pedal 13, the first directional valve 11 and the second directional valve 12 first switch to the 2-position working state. This position cuts off the return oil passage between the front axle brake 14 and the rear axle brake 16, preparing for brake pressure build-up. As the brake pedal 13 is further depressed, the first directional valve 11 and the second directional valve 12 further switch to the 3-position working state. At this time, hydraulic oil from the load-sensitive system enters the front axle brake 14 sequentially through the first check valve 8, the second check valve 9, and the first directional valve 11; simultaneously, the pressurized oil also enters the rear axle brake 16 through the first check valve 8, the third check valve 10, the second directional valve 12, and the shuttle valve 15, thereby putting both the front and rear axle brakes into braking mode.

[0046] The first accumulator 20, the second accumulator 21, and the third accumulator 22 in the braking system of this embodiment are used to provide pressure buffering and stabilization for the parking brake 19, the rear axle brake 16, and the front axle brake 14, respectively. When the vehicle needs to be parked, the third directional valve 18 switches to the 1st position, and hydraulic oil enters the parking brake 19 to realize the parking brake function.

[0047] The method for automatically adjusting the output pressure of a load-sensitive mining dump truck braking system is as follows:

[0048] One end of the load-sensitive valve 5 is connected to the output end of the variable pump 2, and the other end is connected to the brake oil circuit of the front axle brake 14 and the rear axle brake 16. When the vehicle is in a non-braking state, both the first reversing valve 11 and the second reversing valve 12 are in position 1. The hydraulic oil output by the variable pump 2 cannot enter the brake circuit through the first reversing valve 11 and the second reversing valve 12, and the system pressure gradually increases. When the system pressure rises to the set pressure of the load-sensitive valve 5, the hydraulic oil pushes the valve core of the load-sensitive valve 5 to move to the right against the spring force, so that the load-sensitive valve 5 switches to position 1. At this time, the hydraulic oil flows into the variable cylinder 4 through the load-sensitive valve 5 and the pressure compensation valve 6 in sequence, pushing the piston of the variable cylinder 4 to move to the left, thereby reducing the swashplate angle of the variable pump 2 to reduce its displacement, and thus reducing the system output pressure. Under this adjustment, the variable pump 2 finally stabilizes at the minimum displacement state, at which time its output power is the lowest, the output pressure is the lowest, and the system energy consumption and heat generation are also reduced to the lowest. At the same time, the piston of the cylinder 3 moves to the right under the pressure and is in a compression state.

[0049] When the vehicle is under braking, both the first directional valve 11 and the second directional valve 12 switch to the 3-position operating state. If the output pressure of the variable pump 2 is lower than the pressure required by the front axle brake 14 and the rear axle brake 16, the load-sensitive valve 5 remains in the 2-position operating state under the action of its internal spring. At this time, the spring in the cylinder 3 pushes its piston to the left, increasing the swashplate angle of the variable pump 2 through mechanical connection, thereby increasing the output pressure of the variable pump 2 until it reaches the pressure level required by the brakes. During this process, the piston of the variable cylinder 4 moves to the right, and the hydraulic oil in its chamber flows back to the oil tank 7 through the pressure compensation valve 6 and the load-sensitive valve 5. This process constitutes the pressurization stage of the system, the purpose of which is to increase the output pressure of the variable pump 2 to a level that meets the braking requirements of the front and rear axle brakes.

[0050] As the output pressure of variable pump 2 gradually reaches and exceeds the pressure required by the front axle brake 14 and the rear axle brake 16, the pressure of the load-sensitive system continues to rise. When the pressure rises again to the set pressure of load-sensitive valve 5, the hydraulic oil pushes the valve core of load-sensitive valve 5 to move to the right, switching it to the 1st position. At this time, the hydraulic oil flows through load-sensitive valve 5 and pressure compensation valve 6 into variable cylinder 4, pushing the piston of variable cylinder 4 to move to the left, reducing the displacement of variable pump 2 and lowering its output pressure.

[0051] The above process automatically adjusts the output displacement and pressure of the variable pump 2 by judging the relationship between the output pressure of the variable pump 2 and the braking pressure required by the front axle brake 14 and the rear axle brake 16 in real time, thereby realizing closed-loop control of the system output pressure and ultimately achieving the goal of dynamically distributing hydraulic power according to the actual braking needs and saving energy and reducing consumption.

Claims

1. A load-sensitive braking system for mining dump trucks, characterized in that, The load-sensitive mining dump truck braking system includes a load-sensitive system and a braking system. The load-sensitive system compares the output pressure of the power source with the actual braking demand pressure in real time through a pressure detection and feedback mechanism, and automatically adjusts the displacement of the hydraulic pump accordingly, so that the output pressure of the load-sensitive mining dump truck braking system dynamically matches the braking demand. The braking system includes a service brake circuit and an independent parking brake circuit, and the braking state can be switched and controlled by the driver. The load-sensitive system includes a motor (1), a variable pump (2), a hydraulic cylinder (3), a variable cylinder (4), a load-sensitive valve (5), a pressure compensation valve (6), and an oil tank (7); the motor (1) is connected to and drives the variable pump (2); the hydraulic cylinder (3) cooperates with the variable cylinder (4) to adjust the output displacement and pressure of the variable pump (2); the load-sensitive valve (5) is used to detect the output pressure of the variable pump (2) and the pressure required by the braking system, and adjusts the control pressure of the variable cylinder (4) according to the difference between the two; the pressure compensation valve (6) is used to provide stable pressure compensation in the system to ensure the control accuracy of the load-sensitive valve (5); The braking system mainly includes a first check valve (8), a second check valve (9), a third check valve (10), a first reversing valve (11), a second reversing valve (12), a brake pedal (13), a front axle brake (14), a shuttle valve (15), a rear axle brake (16), a fourth check valve (17), a third reversing valve (18), and a parking brake (19). The brake pedal (13) is linked to the valve cores of the first reversing valve (11) and the second reversing valve (12), and its pedal stroke corresponds linearly to the valve core displacement, thereby achieving synchronous control of the working positions of the two reversing valves. The oil inlet P1 of the first reversing valve (11) is connected to the oil outlet of the second check valve (9), and the oil outlet A1 is connected to the front axle brake (14). The oil inlet of the first valve is fixedly connected, and the return port T1 is connected to the oil tank (7) pipeline, which is used to control the on / off and pressure transmission of the front axle brake circuit; the oil inlet P2 of the second reversing valve (12) is connected to the oil outlet pipeline of the third check valve (10), the oil outlet A2 is connected to the first oil inlet pipeline of the shuttle valve (15), the return port T2 is connected to the oil tank (7) pipeline, and the oil outlet of the shuttle valve (15) is fixedly connected to the oil inlet of the rear axle brake (16); the oil inlet P3 of the third reversing valve (18) is connected to the oil outlet pipeline of the fourth check valve (17), the oil outlet A3 is fixedly connected to the oil inlet of the parking brake (19), and the return port T3 is connected to the oil tank (7) pipeline, which is used to realize independent on / off control of the parking brake circuit.

2. The load-sensitive braking system for a mining dump truck according to claim 1, characterized in that, The braking system: The oil inlet of the first check valve (8) is connected to the oil outlet of the variable pump (2) in the load-sensitive system through the main oil supply pipe, forming the main oil inlet channel of the braking system. Its oil outlet is connected to the oil inlets of the second check valve (9), the third check valve (10), and the fourth check valve (17) through branch pipes, respectively, to realize parallel oil supply to the service brake circuit and the parking brake circuit. The first check valve (8), the second check valve (9), the third check valve (10), and the fourth check valve (17) are all installed in a forward-biased and reverse-biased direction, and are connected in series in each branch oil supply circuit to prevent the hydraulic oil in each brake circuit from flowing back in reverse, avoid pressure interference between circuits, and ensure that the pressure of each circuit is independent and stable.

3. The load-sensitive braking system for a mining dump truck according to claim 2, characterized in that, The braking system also includes a first accumulator (20), a second accumulator (21), and a third accumulator (22), which are used to provide pressure buffering and stabilization for the parking brake (19), the rear axle brake (16), and the front axle brake (14), respectively; specifically: The third accumulator (22) is connected in parallel between the oil inlet of the front axle brake (14) and the oil outlet A1 of the first reversing valve (11) via a branch pipeline. The second accumulator (21) is connected in parallel between the oil inlet of the rear axle brake (16) and the oil outlet of the shuttle valve (15). The first accumulator (20) is connected in parallel between the oil inlet of the parking brake (19) and the oil outlet A3 of the third reversing valve (18). All three are sealed to the corresponding circuits through pressure interfaces. The first accumulator (20), the second accumulator (21), and the third accumulator (22) are all bladder-type structures.

4. A load-sensitive braking system for a mining dump truck according to claim 3, characterized in that, The braking system: The first reversing valve (11) and the second reversing valve (12) are each provided with position 1, position 2 and position 3, where position 1 is the non-braking position, position 2 is the pressure build-up preparation position and position 3 is the braking working position; when position 1, the oil inlet port P1 / P2 is closed and the oil return port T1 / T2 is connected to the oil outlet port A1 / A2 to realize the brake pressure relief and oil return; when position 2, the oil return port T1 / T2 is closed and both the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are closed to prepare for brake pressure build-up; when position 3, the oil inlet port P1 / P2 and the oil outlet port A1 / A2 are connected and the oil return port T1 / T2 is closed to realize the delivery of pressurized oil to the brake; The third directional valve (18) has a 1-position and a 2-position, where the 1-position is the parking brake position and the 2-position is the parking release position. When in the 1-position, the oil inlet P3 and the oil outlet A3 are connected, and the oil return T3 is closed, so the pressurized oil enters the parking brake (19) to lock it. When in the 2-position, the oil outlet A3 and the oil return T3 are connected, and the oil inlet P3 is closed, so the hydraulic oil in the parking brake (19) flows back to unlock it. When the vehicle needs to be parked, the third directional valve (18) switches to the 1-position working state, and the hydraulic oil enters the parking brake (19) to realize the parking brake function.

5. A load-sensitive braking system for a mining dump truck according to claim 4, characterized in that, The braking system: The shuttle valve (15) can automatically identify and open the side with higher pressure between the first and second oil inlets to ensure that the rear axle brake (16) obtains a stable maximum braking pressure and avoids brake failure. The front axle brake (14) and rear axle brake (16) are hydraulic caliper disc brakes, which generate braking torque through hydraulic drive to decelerate or stop the vehicle. The parking brake (19) is a hydraulically driven mechanical locking type. It locks the vehicle by engaging with the wheel hub through a locking mechanism to prevent it from rolling away.

6. A load-sensitive braking system for a mining dump truck according to claim 5, characterized in that, The brake pedal (13) is linked to the valve cores of the first reversing valve (11) and the second reversing valve (12) respectively through a mechanical transmission mechanism; the second oil inlet of the shuttle valve (15) is reserved with an expansion interface to adapt to the multi-bridge braking system; the first reversing valve (11) and the second reversing valve (12) are both three-position three-way reversing valves; the third reversing valve (18) is a two-position three-way reversing valve.

7. A load-sensitive braking system for a mining dump truck according to claim 6, characterized in that, In the load-sensitive system, the output pressure of the variable pump (2) is compared with the brake demand pressure in real time by the load-sensitive valve (5), and the displacement of the variable pump (2) is automatically adjusted accordingly to achieve adaptive control of the output pressure. When the system pressure is higher than the set value, the load-sensitive valve (5) switches to the first working position, and the pressure oil drives the variable cylinder (4) to reduce the displacement of the variable pump (2) to reduce the pressure. When the braking demand is higher than the pump output pressure, the load-sensitive valve (5) switches to the second working position, and the spring of the cylinder (3) pushes the variable pump (2) to increase the displacement and increase the pressure. Through closed-loop regulation, the output pressure is always dynamically matched with the braking demand to achieve on-demand pressure supply.

8. A load-sensitive braking system for a mining dump truck according to claim 7, characterized in that, The driver controls the working positions of the first reversing valve (11) and the second reversing valve (12) by operating the brake pedal (13), thereby realizing the switching of the braking system between non-braking and braking states; specifically: When the brake pedal (13) is not pressed, the first reversing valve (11) and the second reversing valve (12) are both in the initial 1 position working state. At this time, the pressure oil circuit from the load-sensitive system is cut off, and the front axle brake (14) and the rear axle brake (16) are both in the release state. The hydraulic oil inside them returns directly to the oil tank (7) through the circuit. When the driver presses the brake pedal (13), the first directional valve (11) and the second directional valve (12) first switch to the 2-position working state, which cuts off the return oil passage between the front axle brake (14) and the rear axle brake (16). As the brake pedal (13) continues to be pressed, the first directional valve (11) and the second directional valve (12) further switch to the 3-position working state. At this time, the hydraulic oil from the load-sensitive system enters the front axle brake (14) through the first check valve (8), the second check valve (9) and the first directional valve (11) in sequence. At the same time, the pressure oil also enters the rear axle brake (16) through the first check valve (8), the third check valve (10), the second directional valve (12) and the shuttle valve (15), so that both the front and rear axle brakes enter the braking state.

9. A method of using the load-sensitive mining dump truck braking system according to any one of claims 1-8, characterized in that, It can automatically adjust the output pressure, including the following steps: Step 1: The system is initially in standby mode, and is started in a non-braking state; When the vehicle is not braking, the brake pedal (13) is not depressed, and the first reversing valve (11) and the second reversing valve (12) are both in the initial 1 position working state. At this time, the motor (1) in the load-sensitive system drives the variable pump (2) to run. The variable pump (2) draws hydraulic oil from the oil tank (7) and outputs it. The braking circuit is in the open circuit state. Step 2: Adaptive pressure adjustment in non-braking state; For the hydraulic oil continuously output by the variable pump (2) in step 1, when the system pressure rises to the preset pressure threshold of the load-sensitive valve (5), the load-sensitive valve (5) switches to the 1st position working state; then, the hydraulic oil flows into the variable cylinder (4) through the load-sensitive valve (5) and the pressure compensation valve (6) in sequence, pushing the piston of the variable cylinder (4) to move, the output displacement of the variable pump (2) decreases, and the system output pressure decreases synchronously until the variable pump (2) stabilizes at the minimum displacement state. At this time, the output power and output pressure of the variable pump (2) are at their lowest, and the system energy consumption and heat generation are reduced to the lowest level; at the same time, the piston of the cylinder (3) moves to the right under the action of the system pressure and remains in a compressed state, completing the low-pressure energy-saving regulation in the non-braking state; Step 3: Braking and boosting preparation; When the driver presses the brake pedal (13), the brake pedal (13) drives the first reversing valve (11) and the second reversing valve (12) to switch to the 3-position working state in a synchronized manner, the brake circuit is connected, and the front axle brake (14) and the rear axle brake (16) enter the braking preparation state; one end of the load-sensitive valve (5) detects the output pressure of the variable pump (2) in real time, and the other end detects the braking pressure required by the front axle brake (14) and the rear axle brake (16) through the feedback pipeline, forming a pressure comparison; Step 4: Brake boost adjustment; For the two sets of pressures detected by the load-sensitive valve (5) in step 3, if the output pressure of the variable pump (2) is lower than the braking pressure required by the front axle brake (14) and the rear axle brake (16), the load-sensitive valve (5) remains in position 2 under the action of its internal spring; at this time, the cylinder (3) pushes the piston of the cylinder (3) to move, thereby increasing the output pressure of the variable pump (2); during this process, the hydraulic oil in the chamber of the variable cylinder (4) flows back to the oil tank (7) through the pressure compensation valve (6) and the load-sensitive valve (5); until the output pressure of the variable pump (2) reaches the braking pressure level required by the front axle brake (14) and the rear axle brake (16), the braking boosting stage is completed; Step 5: Adjust and stabilize the braking pressure; For the system that reaches the braking pressure requirement in step 4, if the variable pump (2) continues to output, causing the system pressure to continue to rise and exceed the preset pressure threshold of the load-sensitive valve (5), the excess pressure will push the valve core of the load-sensitive valve (5) to move again, causing the load-sensitive valve (5) to switch to the 1st position working state; then, the hydraulic oil flows through the load-sensitive valve (5) and the pressure compensation valve (6) into the variable cylinder (4), pushing the piston of the variable cylinder (4) to move, thereby reducing the output displacement of the variable pump (2); as the displacement of the variable pump (2) decreases, the system output pressure decreases synchronously until it is precisely matched with the braking pressure required by the front axle brake (14) and the rear axle brake (16), maintaining the stability of the braking process; Step 6: Braking ends and system reset; When the driver releases the brake pedal (13), the first reversing valve (11) and the second reversing valve (12) switch back to the 1st position working state under the action of the reset mechanism, the brake circuit is disconnected, the hydraulic oil in the front axle brake (14) and the rear axle brake (16) flows back to the oil tank (7) through the circuit, and the brakes are released; at the same time, the system pressure gradually decreases, the load sensitive valve (5) is reset under the action of the internal spring force, the piston of the variable cylinder (4) moves, pushing the variable pump (2) to return to the initial state, and the system returns to the initial standby state of step 1, waiting for the next braking operation.

Images