Construction machine hydraulic system and control method thereof

Abstract

The application provides an engineering machinery hydraulic system and a control method thereof, comprising an oil tank, a gear pump, a filling valve, a first accumulator, a second accumulator, a double-circuit brake valve, a circulating valve, a first axle cooling fan, a cooling valve, a second axle cooling fan, a front axle and a rear axle; an oil inlet of the gear pump is communicated with the oil tank, an oil outlet is communicated with a main oil inlet P0 of the filling valve, an A01 oil port of the filling valve is connected with the front axle in sequence through the first accumulator and the double-circuit brake valve, an A00 oil port of the filling valve is connected with the rear axle in sequence through the second accumulator and the double-circuit brake valve; an O oil port of the filling valve is connected with a circulating valve oil inlet P1, an A1 oil port of the circulating valve is communicated with the first axle cooling fan and the second axle cooling fan through the cooling valve, and a T oil port of the circulating valve is connected with the oil tank. The hydraulic energy originally returned to the oil tank is converted into mechanical energy of the fan, and the problems of efficiency reduction, aging of sealing elements and damage of components caused by continuous increase of oil temperature during operation of the engineering vehicle are solved.

Description

Technical Field

[0001] This application relates to the field of hydraulic technology, specifically to a hydraulic system for engineering machinery and its control method. Background Technology

[0002] In the field of engineering vehicles, hydraulic systems perform multiple functions, including service braking, driving working devices, and system cooling. Their performance directly impacts the overall operating efficiency, safety, and reliability of the vehicle. During operation, the hydraulic fluid temperature continuously rises. Excessively high oil temperatures can lead to decreased system efficiency, accelerated aging of seals, and even component damage. Existing hydraulic system cooling solutions often rely on independent cooling circuits or fan-driven systems, requiring additional power sources and control components. This not only increases system complexity and manufacturing costs but also occupies limited vehicle space.

[0003] Furthermore, construction machinery often operates in cold regions. For closed-loop hydraulic systems, when the equipment is idle or inactive for extended periods, the oil temperature drops rapidly and the viscosity increases significantly, making it difficult to draw oil upon restarting and easily damaging the hydraulic pump. Therefore, an active heating system is needed to maintain the oil temperature. However, large construction machinery typically integrates multiple functions, and constraints such as limited space in the vehicle layout and cost control make it difficult to equip it with multiple independent oil pumps. Summary of the Invention

[0004] To address the problems in the prior art, the first aspect of this application provides a hydraulic system for engineering machinery, including an oil tank, a gear pump, a filling valve, a first accumulator, a second accumulator, a dual-circuit brake valve, a circulation valve, a first axle cooling fan, a cooling valve, a second axle cooling fan, a front axle, and a rear axle. The oil inlet of the gear pump is connected to the oil tank, and the oil outlet is connected to the main oil inlet P0 of the filling valve. The A01 oil port of the filling valve is connected to the front axle in sequence through the first accumulator and the dual-circuit brake valve. The A00 oil port of the filling valve is connected to the rear axle in sequence through the second accumulator and the dual-circuit brake valve. The O port of the filling valve is connected to the P1 port of the circulation valve. The A1 port of the circulation valve is connected to the cooling fan of the first bridge and the cooling fan of the second bridge through the cooling valve. The T port of the circulation valve is connected to the oil tank.

[0005] Furthermore, the A01 port of the filling valve is connected to the first accumulator, the first accumulator is connected to the inlet P4 of the dual-circuit brake valve, and the outlet A3 of the dual-circuit brake valve is connected to the front axle; the A00 port of the filling valve is connected to the second accumulator, the second accumulator is connected to the inlet P3 of the dual-circuit brake valve, and the outlet A4 of the dual-circuit brake valve is connected to the rear axle.

[0006] Furthermore, the A1 oil port of the circulation valve is connected to the P2 oil port of the cooling valve, the T oil port of the circulation valve is connected to the oil tank, the A21 oil outlet of the cooling valve is connected to the oil inlet of the second bridge cooling fan, and the A22 oil outlet of the cooling valve is connected to the oil inlet of the first bridge cooling fan.

[0007] Furthermore, the circulation valve includes a two-position four-way solenoid directional valve and a first relief valve. The first oil outlet of the two-position four-way solenoid directional valve is connected to the A1 oil port of the circulation valve, and the second oil outlet is connected to the oil tank through the first relief valve.

[0008] Furthermore, the gear pump has a second relief valve integrated inside, and the set pressure p2 of the second relief valve is greater than the set pressure p1 of the first relief valve.

[0009] Furthermore, the cooling valve includes a two-position two-way solenoid directional valve, a check valve, and a flow divider valve. The oil inlet of the two-position two-way solenoid directional valve is connected to the oil inlet P2 of the cooling valve, and the oil outlet is connected to the oil return port T2 of the cooling valve. The oil inlet of the flow divider valve is connected to the oil inlet P2 of the cooling valve. The first oil outlet is connected to the oil inlet of the second bridge cooling fan through the oil outlet A21 of the cooling valve, and the second oil outlet is connected to the oil inlet of the first bridge cooling fan through the oil outlet A22 of the cooling valve.

[0010] Furthermore, it also includes a controller, a hydraulic oil temperature sensor installed in the hydraulic system, and an axle oil temperature sensor installed in the axle cooling oil system. The controller is electrically connected to the hydraulic oil temperature sensor, the axle oil temperature sensor, the two-position four-way solenoid directional valve, and the two-position two-way solenoid directional valve, respectively.

[0011] A second aspect of this application provides a control method for a hydraulic system of engineering machinery based on any one of the above claims, comprising: When the pressure of the first accumulator and the second accumulator reaches the set high pressure threshold, the filling valve cuts off the filling of the accumulator and opens the O oil port of the filling valve, so that the pressure oil output by the gear pump is supplied to the circulation valve and the cooling valve through the O oil port. When the pressure in the first and second accumulators drops to a set low-pressure threshold due to braking, the filling valve resumes filling, causing the gear pump to refill the accumulators.

[0012] Furthermore, it also includes: The hydraulic oil temperature in the hydraulic system and the axle cooling oil temperature in the axle cooling oil system are obtained when the vehicle is idling. When the bridge cooling oil temperature is lower than the second temperature threshold, the two-position two-way solenoid valve is energized, the P2 port of the cooling valve is connected to the oil tank, and the first bridge cooling fan and the second bridge cooling fan stop working. When the hydraulic oil temperature is less than the first temperature threshold and the bridge cooling oil temperature is less than the second temperature threshold, the two-position four-way solenoid directional valve is energized, and the P1 port of the circulation valve is connected to the inlet port of the first relief valve; when the oil pressure is higher than the set pressure p1 of the first relief valve, the first relief valve opens to overflow and generate heat.

[0013] Furthermore, the first temperature threshold is 50°C, and the second temperature threshold is 60°C.

[0014] Compared with the prior art, the beneficial effects of this application are: The gear pump in this application charges the first and second accumulators via a charging valve. When the first and second accumulators reach a set high-pressure threshold, the charging valve cuts off the charging passage and opens the O-port, allowing the pressurized oil output by the gear pump to enter the first and second axle cooling fans via a circulation valve and a cooling valve, driving the fans to rotate and reduce the system oil temperature. Without adding an independent cooling power source, the hydraulic energy that would normally return directly to the oil tank is converted into the mechanical energy of the fans. This solves the problems of decreased efficiency, aging seals, and component damage caused by continuously rising oil temperature during engineering vehicle operation. It also avoids the additional power source and control components required by traditional independent cooling circuits, significantly reducing system complexity and manufacturing costs, while saving limited space resources in the vehicle.

[0015] When the vehicle is idling, if the hydraulic oil temperature is lower than the first temperature threshold and the axle cooling oil temperature is lower than the second temperature threshold, the first overflow valve in the circulation valve will throttle and generate heat to achieve closed-loop self-heating and oil temperature maintenance. This function is especially suitable for closed hydraulic systems operating in cold regions. When the equipment is idle or does not operate for a long time, causing the oil temperature to drop rapidly and the viscosity to increase significantly, the circulation valve can be controlled to make the oil overflow and generate heat continuously, effectively increasing the oil temperature in the oil tank and reducing the oil viscosity, thereby improving the oil suction conditions when the gear pump is started next time and avoiding pump damage caused by difficulty in oil suction. Attached Figure Description

[0016] Figure 1 This is a hydraulic schematic diagram of the hydraulic system for the engineering machinery described in this application; Figure 2 This is a hydraulic schematic diagram of the circulation valve in this application; Figure 3 This is a hydraulic schematic diagram of the heat dissipation valve of this application; In the picture: 1. Fuel tank; 2. Gear pump; 3. Filling valve; 4. First accumulator; 5. Second accumulator; 6. Dual-circuit brake valve; 7. Circulation valve; 71. Two-position four-way solenoid directional valve; 72. Overflow valve; 8. First axle cooling fan; 9. Cooling valve; 91. Two-way solenoid directional valve; 92. Check valve; 93. Diverter valve; 10. Second axle cooling fan; 11. Front axle; 12. Rear axle. Detailed Implementation

[0017] To facilitate understanding of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] refer to Figure 1 As shown, this application provides a hydraulic system for engineering machinery, including an oil tank 1, a gear pump 2, a filling valve 3, a first accumulator 4, a second accumulator 5, a dual-circuit brake valve 6, a circulation valve 7, a first axle cooling fan 8, a cooling valve 9, a second axle cooling fan 10, a front axle 11, and a rear axle 12. Specifically, the inlet of gear pump 2 is connected to oil tank 1, and the outlet is connected to the main inlet P0 of filling valve 3. The A01 port of filling valve 3 is connected to the front axle 11 via the first accumulator 4 and the dual-circuit brake valve 6. The A00 port of filling valve 3 is connected to the rear axle 12 via the second accumulator 5 and the dual-circuit brake valve 6. Specifically, the A01 port of filling valve 3 is connected to the first accumulator 4, the first accumulator 4 is connected to the inlet P4 of the dual-circuit brake valve 6, and the outlet A3 of the dual-circuit brake valve 6 is connected to the front axle 11. The A00 port of filling valve 3 is connected to the second accumulator 5, the second accumulator 5 is connected to the inlet P3 of the dual-circuit brake valve 6, and the outlet A4 of the dual-circuit brake valve 6 is connected to the rear axle 12.

[0019] The O port of the filling valve 3 is connected to the P1 inlet of the circulation valve 7. The A1 port of the circulation valve 7 is connected to the first bridge cooling fan 8 and the second bridge cooling fan 10 via the cooling valve 9. The T port of the circulation valve 7 is connected to the oil tank 1. Specifically, the A1 port of the circulation valve 7 is connected to the P2 port of the cooling valve 9, the T port of the circulation valve 7 is connected to the oil tank 1, the A21 outlet of the cooling valve 9 is connected to the inlet of the second bridge cooling fan 10, and the A22 outlet of the cooling valve 9 is connected to the inlet of the first bridge cooling fan 8.

[0020] In this embodiment, gear pump 2 charges the first accumulator 4 and the second accumulator 5 through charging valve 3. When the first accumulator 4 and the second accumulator 5 reach the set high pressure threshold, charging valve 3 cuts off the charging passage and opens port O, allowing the pressure oil output by gear pump 2 to enter the first axle cooling fan 8 and the second axle cooling fan 10 through circulation valve 7 and cooling valve 9, driving the fans to rotate and reduce the system oil temperature. Without adding an independent cooling power source, the hydraulic energy that originally returned directly to the oil tank is converted into the mechanical energy of the fan. This solves the problems of efficiency reduction, seal aging and component damage caused by the continuous rise in oil temperature during the operation of engineering vehicles, and avoids the additional power source and control components required by the traditional independent cooling circuit. This significantly reduces system complexity and manufacturing cost, while saving the limited space resources of the vehicle.

[0021] In some embodiments, reference Figure 2 As shown, the circulation valve 7 includes a two-position four-way solenoid directional valve 71 and a first relief valve 72. The first oil outlet of the two-position four-way solenoid directional valve 71 is connected to the A1 oil port of the circulation valve 7, and the second oil outlet is connected to the oil tank 1 through the first relief valve 72. When the solenoid coil SW1 of the two-position four-way solenoid directional valve 71 is energized, the two-position four-way directional valve 71 is in the upper position, the P1 oil port of the circulation valve 7 is connected to the oil inlet of the first relief valve 72, and the oil supply to the bridge cooling valve 9 is cut off. When the oil pressure is higher than the set pressure p1 of the first relief valve 72, the first relief valve 72 opens to overflow and generate heat. When SW1 is de-energized, the two-position four-way directional valve 71 is in the lower position, the P1 oil port of the circulation valve 7 is connected to the oil outlet A1 of the circulation valve 7, and at this time the pressure oil normally supplies oil to the bridge cooling valve (9).

[0022] In some embodiments, the gear pump 2 has a second relief valve integrated inside, and the set pressure p2 of the second relief valve is greater than the set pressure p1 of the first relief valve 72.

[0023] In some embodiments, reference Figure 3 As shown, the cooling valve 9 includes a two-position two-way solenoid directional valve 91, a check valve 92, and a flow divider valve 93. The oil inlet of the two-position two-way solenoid directional valve 91 is connected to the oil inlet P2 of the cooling valve 9, and the oil outlet is connected to the oil return port T2 of the cooling valve 9. The oil inlet of the flow divider valve 93 is connected to the oil inlet P2 of the cooling valve 9. The first oil outlet is connected to the oil inlet of the second bridge cooling fan 10 through the oil outlet A21 of the cooling valve 9, and the second oil outlet is connected to the oil inlet of the first bridge cooling fan 8 through the oil outlet A22 of the cooling valve 9.

[0024] When the solenoid coil SW2 of the two-position two-way solenoid directional valve 91 is energized, the two-position two-way solenoid directional valve 91 is in the upper position, and the pressure oil at port P1 of the circulation valve 7 flows back to the oil tank 1 through the two-position two-way solenoid directional valve 91 and port T2 of the cooling valve 9. At this time, the first bridge cooling fan 8 and the second bridge cooling fan 10 are not working. When the circulation valve 7 and the two-position two-way solenoid directional valve 91 are de-energized, the pressure oil can enter the oil inlet P2 of the cooling valve 9, and then enter port A21 and port A22 respectively through the diverter valve 93, driving the first bridge cooling fan 8 and the second bridge cooling fan 10 to rotate.

[0025] In some embodiments, the system further includes a controller, a hydraulic oil temperature sensor in the hydraulic system, and an axle oil temperature sensor in the axle cooling oil system. The controller is electrically connected to the hydraulic oil temperature sensor, the axle oil temperature sensor, the two-position four-way solenoid directional valve 71, and the two-position two-way solenoid directional valve 91, respectively.

[0026] This application also provides a control method based on the above-mentioned hydraulic system for engineering machinery, including: When the pressure of the first accumulator 4 and the second accumulator 5 reaches the set high pressure threshold, the filling valve 3 cuts off the filling of the accumulator and opens the O oil port of the filling valve 3, so that the pressure oil output by the gear pump 2 is supplied to the circulation valve 7 and the cooling valve 9 through the O oil port. When the pressure of the first accumulator 4 and the second accumulator 5 drops to the set low-pressure threshold due to braking action, the filling valve 3 resumes the filling state, causing the gear pump 2 to refill the accumulator.

[0027] In some embodiments, it also includes: The hydraulic oil temperature in the hydraulic system and the axle cooling oil temperature in the axle cooling oil system are obtained when the vehicle is idling. When the bridge cooling oil temperature is lower than the second temperature threshold, the two-position two-way solenoid valve 91 is energized, the P2 oil port of the cooling valve 9 is connected to the oil tank 1, and the first bridge cooling fan 8 and the second bridge cooling fan 10 stop working. When the hydraulic oil temperature is lower than the first temperature threshold and the bridge cooling oil temperature is lower than the second temperature threshold, the two-position four-way solenoid directional valve 71 is energized, and the P1 port of the circulation valve 7 is connected to the inlet port of the first relief valve 72; when the oil pressure is higher than the set pressure p1 of the first relief valve 72, the first relief valve 72 opens to overflow and generate heat.

[0028] In some embodiments, the first temperature threshold is 50°C and the second temperature threshold is 60°C.

[0029] In this embodiment, when the vehicle is idling, if the hydraulic oil temperature is lower than the first temperature threshold and the axle cooling oil temperature is lower than the second temperature threshold, the first overflow valve 72 in the circulation valve 7 generates heat through throttling to achieve closed-loop self-heating and oil temperature maintenance. This function is particularly suitable for closed-loop hydraulic systems operating in cold regions. When the equipment is idle or does not operate for a long time, causing the oil temperature to drop rapidly and the viscosity to increase significantly, the circulation valve can be controlled to allow the oil to continuously overflow and generate heat, effectively increasing the oil temperature in the oil tank and reducing the oil viscosity, thereby improving the oil suction conditions when the gear pump is started next time and avoiding pump damage caused by difficulty in oil suction.

[0030] This overflow heating technology complements the heat dissipation function mentioned above. When the oil temperature is too high, it prioritizes cooling the cooling fan, and when the oil temperature is too low, it switches to the overflow circuit for heating. Both share the same pump source and the same valve group, eliminating the need for additional heating devices or independent power sources. This expands the environmental adaptability and start-up reliability of the hydraulic system at extremely low additional cost.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A hydraulic system for engineering machinery, characterized in that, It includes an oil tank (1), a gear pump (2), a filling valve (3), a first accumulator (4), a second accumulator (5), a dual-circuit brake valve (6), a circulation valve (7), a first axle cooling fan (8), a cooling valve (9), a second axle cooling fan (10), a front axle (11), and a rear axle (12). The oil inlet of the gear pump (2) is connected to the oil tank (1), and the oil outlet is connected to the main oil inlet P0 of the filling valve (3). The A01 oil port of the filling valve (3) is connected to the front axle (11) in sequence through the first accumulator (4) and the dual-circuit brake valve (6). The A00 oil port of the filling valve (3) is connected to the rear axle (12) in sequence through the second accumulator (5) and the dual-circuit brake valve (6). The O port of the filling valve (3) is connected to the P1 port of the circulation valve (7). The A1 port of the circulation valve (7) is connected to the first bridge cooling fan (8) and the second bridge cooling fan (10) respectively through the cooling valve (9). The T port of the circulation valve (7) is connected to the oil tank (1).

2. The hydraulic system for engineering machinery according to claim 1, characterized in that, The A01 port of the filling valve (3) is connected to the first accumulator (4), the first accumulator (4) is connected to the inlet P4 of the dual-circuit brake valve (6), and the outlet A3 of the dual-circuit brake valve (6) is connected to the front axle (11); the A00 port of the filling valve (3) is connected to the second accumulator (5), the second accumulator (5) is connected to the inlet P3 of the dual-circuit brake valve (6), and the outlet A4 of the dual-circuit brake valve (6) is connected to the rear axle (12).

3. The hydraulic system for engineering machinery according to claim 1, characterized in that, The A1 port of the circulation valve (7) is connected to the P2 port of the cooling valve (9), the T port of the circulation valve (7) is connected to the oil tank (1), the A21 port of the cooling valve (9) is connected to the inlet of the second bridge cooling fan (10), and the A22 port of the cooling valve (9) is connected to the inlet of the first bridge cooling fan (8).

4. The hydraulic system for engineering machinery according to claim 1, characterized in that, The circulation valve (7) includes a two-position four-way solenoid directional valve (71) and a first overflow valve (72). The first oil outlet of the two-position four-way solenoid directional valve (71) is connected to the A1 oil port of the circulation valve (7), and the second oil outlet is connected to the oil tank (1) through the first overflow valve (72).

5. The hydraulic system for engineering machinery according to claim 4, characterized in that, The gear pump (2) has a second overflow valve integrated inside, and the set pressure p2 of the second overflow valve is greater than the set pressure p1 of the first overflow valve (72).

6. The hydraulic system for engineering machinery according to claim 1, characterized in that, The heat dissipation valve (9) includes a two-position two-way solenoid directional valve (91), a one-way valve (92), and a flow divider valve (93). The oil inlet of the two-position two-way solenoid directional valve (91) is connected to the oil inlet P2 of the heat dissipation valve (9), and the oil outlet is connected to the oil return port T2 of the heat dissipation valve (9). The oil inlet of the flow divider valve (93) is connected to the oil inlet P2 of the heat dissipation valve (9). The first oil outlet is connected to the oil inlet of the second bridge cooling fan (10) through the oil outlet A21 of the heat dissipation valve (9), and the second oil outlet is connected to the oil inlet of the first bridge cooling fan (8) through the oil outlet A22 of the heat dissipation valve (9).

7. The hydraulic system for engineering machinery according to claim 1, characterized in that, It also includes a controller, a hydraulic oil temperature sensor installed in the hydraulic system, and an axle oil temperature sensor installed in the axle cooling oil system. The controller is electrically connected to the hydraulic oil temperature sensor, the axle oil temperature sensor, the two-position four-way solenoid directional valve (71), and the two-position two-way solenoid directional valve (91), respectively.

8. A control method for a hydraulic system of engineering machinery according to any one of claims 1-7, characterized in that, include: When the pressure of the first accumulator (4) and the second accumulator (5) reaches the set high pressure threshold, the filling valve (3) cuts off the filling of the accumulator and opens the O port of the filling valve (3), so that the pressure oil output by the gear pump (2) is supplied to the circulation valve (7) and the heat dissipation valve (9) through the O port. When the pressure of the first accumulator (4) and the second accumulator (5) drops to the set low pressure threshold due to braking action, the filling valve (3) resumes filling state, so that the gear pump (2) refills the accumulator.

9. The control method for the hydraulic system of engineering machinery according to claim 8, characterized in that, Also includes: The hydraulic oil temperature in the hydraulic system and the axle cooling oil temperature in the axle cooling oil system are obtained when the vehicle is idling. When the bridge cooling oil temperature is lower than the second temperature threshold, the two-position two-way solenoid valve (91) is energized, the P2 oil port of the heat dissipation valve (9) is connected to the oil tank (1), and the first bridge cooling fan (8) and the second bridge cooling fan (10) stop working. When the hydraulic oil temperature is less than the first temperature threshold and the bridge cooling oil temperature is less than the second temperature threshold, the two-position four-way solenoid directional valve (71) is energized, and the P1 port of the circulation valve (7) is connected to the oil inlet of the first relief valve (72); when the oil pressure is higher than the set pressure p1 of the first relief valve (72), the first relief valve (72) opens to overflow and generate heat.

10. The hydraulic system for engineering machinery according to claim 9, characterized in that, The first temperature threshold is 50°C, and the second temperature threshold is 60°C.

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