Automatic cycle temperature rise and cooling system for excavator and control method thereof

Abstract

The application discloses a kind of excavator automatic circulation temperature rise, cooling system and control method thereof, it belongs to engineering machinery technical field.It solves the defects of low efficiency caused by long heating process time and labor intensity of driver in existing traditional excavator cooling system.Its main structure includes temperature sensor, main pump unit, main control valve unit, controller, circulating temperature rise unit, power compensation unit, auxiliary cooling unit, oil return distribution unit and circulating cooling unit.The oil suction end of main pump unit is connected with hydraulic oil tank, and the oil outlet end is respectively connected with the oil inlet end of main control valve unit, circulating temperature rise unit and auxiliary cooling unit.The oil return end of main control valve unit is connected with the oil inlet of oil return distribution unit, the oil outlet of distribution unit is connected with circulating cooling unit, auxiliary cooling unit supplies stored energy to circulating cooling unit, and the oil outlet of circulating cooling unit is connected with hydraulic oil tank.The application is mainly used in excavator and other engineering machinery.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, and more specifically, it relates to an automatic circulating temperature rise and cooling system for excavators and its control method. Background Technology

[0002] Construction machinery such as excavators often operate in cold regions like high altitudes or hot regions like extreme heat. In cold conditions, to prevent the hydraulic fluid from increasing in viscosity and causing a decrease in pump suction capacity, control accuracy, and sensitivity, the hydraulic oil needs to be heated to a suitable operating temperature after startup. After the hydraulic system has been operating normally for a period of time or in hot environments, the oil temperature may become too high, requiring cooling to maintain it within the optimal temperature range.

[0003] Existing excavator pressure build-up and heating systems, such as Figure 8 As shown, the system includes a hydraulic pump, hydraulic oil tank, control valve, relief valve, bypass shut-off valve, hydraulic actuators, solenoid valves, check valves, electrically controlled check valves, hydraulic oil cooler, fan, oil temperature sensor, and controller. After starting the machine, if the temperature is lower than the operating temperature, the hydraulic oil needs to be heated to reach the standard operating temperature. First, the bypass shut-off valve is closed using a button or switch. Then, the pilot handle is operated to control the control valve, pressurizing the actuators. This pressurization process increases the oil pressure in the working oil circuit, and the heat generated by the overflow valve raises the temperature. When the temperature becomes too high, the fan dissipates heat from the hydraulic oil cooler.

[0004] Therefore, its shortcomings are as follows: 1. Manually operating the pilot handle to heat the hydraulic components by accumulating pressure and overflow increases the driver's workload, and the heating process is time-consuming, inefficient, and affects the lifespan of the hydraulic components; 2. Adding an electric heater, usually placed in the oil tank, only heats a local area, resulting in insufficient heating of the entire hydraulic system, a simple structure, and poor stability and reliability; 3. Heating by adding an additional hydraulic pump and a fixed-value relief valve assembly significantly increases the cost compared to the general solution and occupies installation space. Furthermore, heating using a fixed-value relief valve makes the heating time uncontrollable; 4. Electric heaters easily cause hydraulic oil carbonization, affecting its use; ordinary relief valves have low heating efficiency, and the temperature cannot change linearly according to actual needs; variable speed and displacement increase system flow, which in turn increases power loss and energy loss.

[0005] Therefore, the excavator currently cools the hydraulic oil by a wind-cooled radiator, but when the excavator works in place without moving, the heat transfer efficiency is greatly reduced and the heat dissipation effect is poor by relying on air as the heat transfer medium to dissipate heat, and the control precision is relatively low and the heat dissipation effect is affected by driving the fan directly by the engine or driving the fan by the hydraulic motor to dissipate heat. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and provide an excavator automatic circulating temperature rise and cooling system and a control method thereof.

[0007] In order to achieve the above-mentioned purpose, the present application is realized by adopting the following technical scheme:

[0008] An excavator automatic circulating temperature rise and cooling system, comprising a temperature sensor, a main pump unit, a main control valve unit, a controller, a circulating temperature rise unit, a power compensation unit, an auxiliary cooling unit, an oil return distribution unit and a circulating cooling unit, the oil suction end of the main pump unit is connected with a hydraulic oil tank, the oil outlet ends are respectively connected with the oil inlet end of the main control valve unit, the circulating temperature rise unit and the auxiliary cooling unit, the oil return end of the main control valve unit is connected with the oil inlet of the oil return distribution unit, the oil outlet of the distribution unit is connected with the circulating cooling unit, the auxiliary cooling unit supplies stored energy to the circulating cooling unit, the oil outlet of the circulating cooling unit is connected with the hydraulic oil tank, the oil outlet of the circulating temperature rise unit is connected with the power compensation unit, the output end of the power compensation unit is connected with the input end of the main pump unit, the temperature sensor collects the temperature of the hydraulic oil tank and transmits it to the controller, and the controller is electrically connected with the main pump unit, the main control valve unit, the oil return distribution unit and the circulating cooling unit.

[0009] Preferably, the main pump unit comprises a main pump one, a main pump two and a pilot pump coaxially connected with the engine, the oil suction port of the pilot pump is connected with the hydraulic oil tank 1, and the oil outlet port is communicated to the variable mechanism of the main pump one and the main pump two.

[0010] Preferably, the circulating temperature rise unit comprises a working start valve, a confluence valve, a cartridge flow control valve, an on-off valve and a temperature rise opening valve, the oil outlet ports of the main pump one are respectively connected with the working start valve and the temperature rise opening valve, the oil outlet ports of the main pump two are respectively connected with the working start valve and the confluence valve, the oil outlets of the temperature rise opening valve and the confluence valve after confluence are respectively connected with the oil inlet ports of the cartridge flow control valve and the on-off valve, and the oil outlet port of the on-off valve is connected back to the hydraulic oil tank.

[0011] Preferably, the power compensation unit comprises a hydraulic motor and a pressure compensation valve, the oil outlets of the temperature rise opening valve and the confluence valve after confluence are connected with the B port of the pressure compensation valve, the oil outlet port of the cartridge flow control valve is connected with the P port of the pressure compensation valve, the A port of the pressure compensation valve is connected with the oil inlet port of the hydraulic motor, and the oil outlet port of the hydraulic motor is communicated to the hydraulic oil tank.

[0012] Preferably, the oil return distribution unit comprises a flow meter, a two-way cartridge valve one and a two-way cartridge valve two, the oil return port of the main control valve unit is connected with the flow meter, the flow meter is connected with the oil inlet port of the two-way cartridge valve one and the oil inlet port of the two-way cartridge valve two respectively, and the oil outlet port of the two-way cartridge valve two is connected with the hydraulic oil tank.

[0013] Preferably, the circulating cooling unit comprises a hydraulic oil radiator, a four-way electric proportional water valve, an oil return filter, a cooling water tank, a cooling water pump, a cooling motor and a cooling pump, the oil outlet port of the two-way cartridge valve one returns to the hydraulic oil tank through the hydraulic oil radiator and the oil return filter, the oil outlet port of the cooling pump is connected with the oil inlet port of the cooling motor, the oil outlet port of the cooling motor is connected with the hydraulic oil tank, the cooling motor is coaxially connected with the cooling water pump, the water suction port of the cooling water pump is connected with the cooling water tank, the water outlet port of the cooling water pump is connected with the four-way electric proportional water valve, the outlet of the four-way electric proportional water valve is connected with the water inlet port of the hydraulic oil radiator and the cooling water tank respectively, and the water outlet port of the hydraulic oil radiator is connected to the cooling water tank.

[0014] Preferably, the auxiliary cooling unit comprises an accumulator, a hydraulic control check valve and a check valve two, the oil outlet port of the temperature rise opening valve and the oil outlet port of the merging valve are merged and then connected with the accumulator through the check valve one, the check valve one and the inlet of the accumulator are connected with the oil inlet port of the hydraulic control check valve through a pipeline, the oil outlet port of the hydraulic control check valve is merged with the oil outlet port of the cooling pump through the check valve two and then enters the oil inlet port of the cooling motor.

[0015] A control method, using the excavator automatic circulating temperature rise and cooling system as described above, comprises an automatic circulating heating mode, an oil return cooling mode and a working mode.

[0016] Preferably, the operation method of the automatic circulating heating mode is as follows:

[0017] After starting, the temperature sensor detects the oil temperature of the hydraulic system and compares it with the temperature preset by the controller, assuming that the preset temperature is T1, T2 and T3, wherein T1 < T2 < T3, and the temperature is between T2 and T3, which is the ideal working temperature, when T1 < real-time temperature < T2, the working temperature does not meet the normal working temperature of the excavator, at this time, the working starting valve is powered on, the on-off valve is powered on, and the temperature rising opening valve is powered on, the hydraulic oil output by the main pump one enters the inlet of the cartridge flow control valve, then the controller outputs the current corresponding to the temperature of the hydraulic oil of the cartridge flow control valve through the current-temperature relationship, and the actual feedback current is output through the PID algorithm, so as to change the opening degree of the cartridge flow control valve, so that the oil temperature rises, the heated oil enters the oil inlet of the hydraulic motor through the pressure compensation valve to drive the motor to rotate, the hydraulic motor is coaxially connected with the engine to compensate the torque output of the engine, and at the same time, the hydraulic oil output by the main pump one enters the accumulator for storage through the one-way valve one, at this time, the cooling pump is in zero displacement.

[0018] Preferably, the operation method of the oil return cooling mode is:

[0019] When the real-time temperature > T3, the displacement of the cooling pump is adjusted to a certain displacement, since the cooling pump has pressure oil output, a part of the pressure oil will open the hydraulic control one-way valve, so that the pressure oil stored in the accumulator will drive the cooling motor through the hydraulic control one-way valve, the one-way valve two and the cooling pump, thereby playing an auxiliary cooling role, and reducing the energy output of the cooling pump, the cooling motor provides power for the cooling water pump, the cooling water pump sucks cooling water from the cooling water tank, and then enters the water inlet of the hydraulic oil radiator through the four-way electric proportional water valve to cool the hydraulic oil; since the real-time temperature > T3, that is, the temperature is higher than the ideal working temperature, in order to ensure that the hydraulic oil is sufficiently cooled, the two-way cartridge valve two is powered off, the two-way cartridge valve one is powered on, and the oil return enters the hydraulic oil radiator and returns to the hydraulic oil tank through the two-way cartridge valve one.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] 1、The present application can linearly change the temperature rise of the hydraulic oil according to the actual temperature change by adjusting the opening degree of the flow control valve through the cartridge flow control valve combined with the temperature-current curve set by the controller, and the heating rate, control accuracy and flexibility are high; at the same time, the combined flow valve, the temperature rising opening valve, the on-off valve and other control valves in the heating circuit can realize the automatic circulating temperature rising function through electrical control;

[0022] 2, The application has the following advantages: 1) the plug-in valve can increase the flow area, reduce the pressure loss, and facilitate integration; 2) the electric proportional form can cooperate with the controller and the control algorithm to continuously adjust the displacement of the plug-in flow control valve core, which is beneficial to realize automatic temperature adjustment and linear change; 3) changing the displacement stroke of the valve core, i.e. adjusting the size of the valve port opening, can change the oil flow area, because the fluid velocity through the plug-in flow control valve port increases sharply, and generates a lot of heat through friction, the heating speed is fast, and the temperature rise effect is obvious;

[0023] 3, The pressure compensation valve ensures that the hydraulic oil entering the hydraulic motor is not affected by load changes (including pressure fluctuations, engine speed drop, torque fluctuations, etc.), ensuring stable output of the hydraulic motor, and compensating for the engine output power and stable output in low temperature environment;

[0024] 4, Through the auxiliary cooling unit, i.e. the accumulator combined with the hydraulic control check valve, the accumulator can store hydraulic oil when the system is heated, and release pressure oil for cooling the motor to rotate when cooling, which plays a role in energy saving, and the structure is simple and the cost is low;

[0025] 5, The four-way electric proportional water valve can not only realize proportional continuous adjustment of the flow of hydraulic oil entering the radiator cooler, but also can remove the bypass water overflow valve;

[0026] In summary, the application can automatically and efficiently warm up the excavator and cool the oil according to the temperature of the hydraulic oil in real time, solve the problems of long warming-up time, uncontrollable hydraulic oil warming-up time, relieving engine power drop in low temperature environment, and tedious operation in the prior art; At the same time, the problem of poor hydraulic oil cooling effect is solved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The schematic diagram of the principle of the application;

[0028] Figure 2 The hydraulic principle diagram of the application;

[0029] Figure 3 The principle diagram of the pressure compensation valve in the application;

[0030] Figure 4 The flow chart of the control method in the application;

[0031] Figure 5 The hydraulic oil temperature-plug-in flow control valve current relationship diagram in the application;

[0032] Figure 6 The plug-in flow control valve current-valve core displacement-output flow relationship diagram in the application;

[0033] Figure 7 A schematic diagram of the connection of the four-way proportional water valve in this invention;

[0034] Figure 8 This is a schematic diagram of an existing excavator pressure buildup and heating scheme.

[0035] In the diagram: 1. Hydraulic oil tank; 2. Pilot pump; 3. Main pump one; 4. Main pump two; 5. Engine; 6. Hydraulic motor; 7. Pressure compensation valve; 8. Controller; 9. Working start valve; 10. Main control valve unit; 11. Confluence valve; 12. Accumulator; 13. Check valve one; 14. Cartridge flow control valve; 15. On / off valve; 16. Temperature rise opening valve; 17. Flow meter; 18. Two-way cartridge valve one; 19. Two-way cartridge valve two; 20. Hydraulic oil radiator; 21. Four-way electro-proportional water valve; 22. Hydraulic control check valve; 23. Check valve two; 24. Return oil filter; 25. Cooling water tank; 26. Cooling water pump; 27. Cooling motor; 28. Cooling pump; 29. ​​Temperature sensor. Detailed Implementation

[0036] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0037] Example 1:

[0038] like Figure 1 As shown, an automatic circulating temperature rise and cooling system for an excavator includes a temperature sensor, a main pump unit, a main control valve unit, a controller, a circulating temperature rise unit, a power compensation unit, an auxiliary cooling unit, a return oil distribution unit, and a circulating cooling unit. The suction end of the main pump unit is connected to the hydraulic oil tank, and the outlet end is connected to the inlet end of the main control valve unit, the circulating temperature rise unit, and the auxiliary cooling unit, respectively. The return end of the main control valve unit is connected to the inlet of the return oil distribution unit, and the outlet of the distribution unit is connected to the circulating cooling unit. The auxiliary cooling unit supplies stored energy to the circulating cooling unit. The outlet of the circulating cooling unit is connected to the hydraulic oil tank, and the outlet of the circulating temperature rise unit is connected to the power compensation unit. The output end of the power compensation unit is connected to the input end of the main pump unit. The temperature sensor collects the temperature of the hydraulic oil tank and transmits it to the controller. The controller is electrically connected to the main pump unit, the main control valve unit, the return oil distribution unit, and the circulating cooling unit, respectively.

[0039] Example 2:

[0040] like Figures 2-3 As shown, an automatic circulating temperature rise and cooling system for an excavator differs from Embodiment 1 in that the main pump unit includes a main pump 3, a main pump 4 and a pilot pump 2, which are coaxially connected to the engine 5. The oil suction port of the pilot pump 2 is connected to the hydraulic oil tank 1, and the oil outlet is connected to the variable mechanism of the main pump 3 and the main pump 4.

[0041] Further, the circulating temperature rising unit comprises a working starting valve 9, a merging valve 11, a cartridge flow control valve 14, an on-off valve 15 and a temperature rising opening valve 16, the oil suction port of the main pump one 3 sucks oil from the hydraulic oil tank 1, the oil outlet port of the main pump one 3 is connected with the oil inlet port of the working starting valve 9 and the oil inlet port of the temperature rising opening valve 16 respectively, the oil suction port of the main pump two 4 sucks oil from the hydraulic oil tank 1, the oil outlet port of the main pump two 4 is connected with the oil inlet port B1 of the working starting valve 9 and the oil inlet port A1 of the merging valve 11 respectively, the temperature rising opening valve 16 is merged with the oil outlet port of the merging valve 11 and is connected with the oil inlet port of the cartridge flow control valve 14 and the oil inlet port of the on-off valve 15 respectively, the oil outlet port of the on-off valve 15 is connected back to the hydraulic oil tank 1. Specifically, the oil from the oil outlet port of the main pump one 3 is divided into four paths after being merged with the main pump two 4 through the merging valve 11: one path is connected to the oil inlet port of the on-off valve 15, one path passes through the one-way valve one 13 to enter the accumulator 12, one path enters the oil inlet port of the cartridge flow control valve 14; the other path is connected to the B port of the pressure compensation valve 7 through a pipeline.

[0042] Further, the power compensation unit comprises a hydraulic motor 6 and a pressure compensation valve 7, the temperature rising opening valve 16 is connected with the B port of the pressure compensation valve 7 after being merged with the oil outlet port of the merging valve 11, the oil outlet port of the cartridge flow control valve 14 is connected with the P port of the pressure compensation valve 7, the A port of the pressure compensation valve 7 is connected with the oil inlet port of the hydraulic motor 6, and the oil outlet port of the hydraulic motor 6 is communicated with the hydraulic oil tank 1.

[0043] Further, the oil return distribution unit comprises a flow meter 17, a two-way cartridge valve one 18 and a two-way cartridge valve two 19, the oil return port of the main control valve unit 10 is connected with the flow meter 17, the flow meter 17 is connected with the oil inlet port of the two-way cartridge valve one 18 and the oil inlet port of the two-way cartridge valve two 19 respectively, and the oil outlet port of the two-way cartridge valve two 19 is connected with the hydraulic oil tank 1. The oil supplied by the oil outlet port of the main pump one 3 and the oil supplied by the oil outlet port of the main pump two 4 enters the main control valve unit 10 after passing through the working starting valve 9, and then is supplied to the execution element (not shown in the figure), specifically, the oil return port of the main control valve unit 10 is divided into two paths after being connected with the flow meter 17, one path is connected with the oil inlet port of the two-way cartridge valve two 19, enters the hydraulic oil tank 1 through the oil outlet port of the two-way cartridge valve two 19; the other path is connected with the oil inlet port of the two-way cartridge valve one 18, enters the hydraulic oil tank 1 through the oil outlet port of the two-way cartridge valve one 18, the hydraulic oil radiator 20 and the oil return filter 24.

[0044] As Figure 2 , 7As shown, the circulating cooling unit includes a hydraulic oil radiator 20, a four-way electric proportional water valve 21, an oil return filter 24, a cooling water tank 25, a cooling water pump 26, a cooling motor 27 and a cooling pump 28, the oil outlet of the two-way cartridge valve one 18 is connected back to the hydraulic oil tank 1 through the hydraulic oil radiator 20 and the oil return filter 24, the oil suction port of the cooling pump 28 is connected to the hydraulic oil tank 1, the oil outlet of the cooling pump 28 is connected to the oil inlet of the cooling motor 27, the oil outlet of the cooling motor 27 is connected to the hydraulic oil tank 1, the cooling motor 27 is coaxially connected to the cooling water pump 26, the cooling water tank 25 is placed on the excavator frame, the water suction port of the cooling water pump 26 is connected to the cooling water tank 25, the water outlet of the cooling water pump 26 is divided into two paths and connected to the four-way electric proportional water valve 21, the outlets of the four-way electric proportional water valve 21 are respectively connected to the water inlet of the hydraulic oil radiator 20 and the cooling water tank 25, and the water outlet of the hydraulic oil radiator 20 is connected to the cooling water tank 25.

[0045] Further, the auxiliary cooling unit includes an accumulator 12, a hydraulic control check valve 22 and a check valve two 23, the temperature rise opening valve 16 is further connected to the accumulator 12 through the check valve one 13 after being combined with the oil outlet of the combining valve 11, the check valve one 13 and the inlet of the accumulator 12 are connected through a pipeline to the oil inlet of the hydraulic control check valve 22, the oil outlet of the hydraulic control check valve 22 is combined with the oil outlet of the cooling pump 28 after passing through the check valve two 23 and enters the oil inlet of the cooling motor 27.

[0046] Among them, the work starting valve 9 is a two-position two-way electromagnetic valve, the combining valve 11 is a cartridge two-position three-way or two-position two-way or two-position four-way directional valve, the cartridge flow control valve 14 is a normally open flow control valve or a normally closed proportional flow control valve, the switch valve 15 is a cartridge two-position three-way or two-position two-way or two-position four-way directional valve, the temperature rise opening valve 16 is a two-position three-way or two-position two-way or two-position four-way electromagnetic directional valve, the two-way cartridge valve one 18 and the two-way cartridge valve two 19 are electrically controlled directional valves; the main pump one 3 and the main pump two 4 and the cooling pump 28 are all variable pumps; the hydraulic elements are all connected by pipelines, and the controller 8 is electrically connected with the temperature sensor 29 and the electrical elements.

[0047] Example 3:

[0048] A control method, using the excavator automatic circulating temperature rise and cooling system as described above, including an automatic circulating heating mode, an oil return cooling mode and a working mode.

[0049] The operation method of the automatic circulating heating mode is:

[0050] In combination Figure 2 And Figure 4The working principle of automatic circulating heating is explained as follows: After startup, temperature sensor 29 detects the oil temperature of the hydraulic system and compares it with the temperature preset by controller 8. Assuming the preset temperatures are T1, T2, and T3, where T1 < T2 < T3, and the ideal working temperature is between T2 and T3, when T1 < real-time temperature < T2, the normal working temperature of the excavator is not met. At this time, the working start valve 9, the switching valve 15, and the heating start valve 16 are energized. The hydraulic oil output from the main pump 3 enters the inlet of the cartridge-type flow control valve 14, and then controller 8 controls the flow through the cartridge-type flow control valve 14. The hydraulic oil temperature and current relationship of the flow control valve 14 is calculated, and the output current corresponds to the temperature. This current, along with the actual feedback current, is used in conjunction with a PID algorithm or other control algorithms to output the final control current. This changes the valve opening of the cartridge flow control valve 14, raising the oil temperature. The heated oil then passes through the pressure compensation valve 7 and enters the inlet of the hydraulic motor 6, driving the motor to rotate. The hydraulic motor 6 is coaxially connected to the engine 5, providing compensated torque output for the engine 5. Simultaneously, during the circulating heating process, the hydraulic oil output from the main pump 3 enters the accumulator 12 for storage through the check valve 13. At this time, the cooling pump 28 is at zero displacement. The pressure compensation valve 7 ensures that the hydraulic oil entering the hydraulic motor 6 is not affected by load changes (including pressure fluctuations, engine speed drops, torque fluctuations, etc.), guaranteeing stable output from the hydraulic motor 6. Note: Engine power may decrease or output insufficient power under low temperature or extremely cold conditions.

[0051] The working principle of pressure compensation valve 7 is as follows: Figure 3 As shown, let the inlet pressure of the cartridge flow control valve 14 be P. B The oil outlet pressure is P P The spring force acting on the valve core of pressure compensation valve 7 is Ft, and the area at both ends of the valve core of pressure compensation valve 7 is A. Since the inlet pressure of cartridge flow control valve 14 simultaneously acts on port B of pressure compensation valve, and the outlet pressure of cartridge flow control valve 14 acts on port P of pressure compensation valve, the pressure difference between the inlet and outlet of cartridge flow control valve 14 is ΔP = P. B -P P =Ft / A, because the pressure difference between the inlet and outlet of the cartridge flow control valve 14 determines the flow rate through the cartridge flow control valve 14. Therefore, when the opening of the cartridge flow control valve 14 is constant, changes in the system load will affect P. A or P B The change in pressure, through the action of pressure compensation valve 7, makes ΔP=Ft / A, ensuring that the output flow of cartridge flow control valve 14 remains constant.

[0052] A schematic diagram of the current-temperature relationship of the cartridge flow control valve 14 is shown below. Figure 5 As shown, its relational expression is:

[0053]

[0054] The controller 8 outputs a control current according to the expression.

[0055] The above expression is calculated according to Figure 5 The controller 8 calculates the temperature signal, outputs a current corresponding to the temperature, and outputs a final control current through a PID algorithm or other control algorithm with the actual feedback current, so as to change the opening degree of the valve port of the plug-in flow control valve 14 and increase the oil temperature, wherein I is the actual control current output by the controller 8, I1 is the control current at extremely cold temperature, Imax is the maximum control current of the plug-in flow control valve 14, Imin is the minimum control current of the plug-in flow control valve 14, T is the actual temperature, T1 is the preset temperature 1, and T2 is the preset temperature 2.

[0056] Figure 6 The figure shows the relationship between the current of the plug-in flow control valve 14, the displacement of the plug-in flow control valve 14, and the output flow, wherein the horizontal axis represents the current of the plug-in flow control valve 14, the left vertical axis represents the displacement or stroke of the plug-in flow control valve 14, and the right vertical axis represents the output flow of the plug-in flow control valve 14. Figure 7 It can be seen that when the current increases, the displacement of the plug-in flow control valve 14 increases linearly, the valve core opening increases, and the flow through the valve port increases in a curve; when the current is small, the valve core opening is small, and the oil temperature rises fast; when the current is large, the valve core opening is large, and the oil temperature rises slowly.

[0057] The plug-in flow control valve 14 has the following advantages: 1. The plug-in valve can increase the flow area, reduce the pressure loss, and be integrated; 2. The electric proportional form can cooperate with the controller 8 and the control algorithm to continuously adjust the displacement of the plug-in flow control valve 14, which is conducive to realizing automatic temperature adjustment and linear change; 3. Changing the displacement stroke of the valve core, i.e. adjusting the opening degree of the valve port, can change the oil flow area. Since the fluid velocity of the oil passing through the valve port of the plug-in flow control valve 14 increases sharply and generates a large amount of heat through friction, the heating speed is fast, and the temperature rise effect is obvious.

[0058] The operation method of the oil return cooling mode is as follows:

[0059] When the real-time temperature > T3, the cooling pump 28 adjusts the displacement to a certain displacement, and since the cooling pump 28 has a pressure oil output, part of the pressure oil will open the hydraulic control check valve 22, so that the pressure oil stored in the accumulator 12 will drive the cooling motor 27 together with the cooling pump 28 through the hydraulic control check valve 22 and the check valve 23, thereby playing a role in assisting cooling, and reducing the energy output of the cooling pump 28, the cooling motor 27 provides power for the cooling water pump 26, the cooling water pump 26 sucks cooling water from the cooling water tank 25, the outlet of the hydraulic oil radiator 20 is connected to the cooling water tank 25, and then passes through the four-way electric proportional water valve 21 to enter the inlet of the hydraulic oil radiator 20 for hydraulic oil cooling; the four-way electric proportional water valve 21 can change the current size to change the valve core opening, on the one hand, it can continuously adjust the flow entering the hydraulic oil radiator 20; on the other hand, it can realize that the excess cooling water returns to the cooling water tank 25, thereby protecting the hydraulic oil radiator 20, avoiding the existence of a relief valve in the cooling system, improving the structure, and reducing the energy loss caused by overflow. Since the real-time temperature > T3, that is, the temperature is higher than the ideal working temperature, in order to ensure that the hydraulic oil is sufficiently cooled, the two-way cartridge valve two 19 is de-energized and the two-way cartridge valve one 18 is energized, and the return oil enters the hydraulic oil radiator 20 and returns to the hydraulic oil tank 1 through the two-way cartridge valve one 18.

[0060] The operation method of the working mode is as follows:

[0061] When the real-time temperature < T1, that is, in a low temperature or extremely cold environment, the combined valve 11 is energized, and the oil of the main pump two 4 can be combined with the main pump one 3 through the combined valve 11 and pass through the cartridge flow control valve 14 for heating. At this time, the combined flow is increased, the heating rate is improved, and it is beneficial to shorten the warm-up time in an extremely cold environment;

[0062] When T2 < real-time temperature < T3, the temperature is the ideal temperature for the excavator to work, at this time, the working start valve 9 is de-energized, the on-off valve 15 is de-energized, and the temperature rise opening valve 16 is de-energized, and the excavator enters the working mode; the pressure oil output by the main pump one 3 and the main pump two 4 enters the actuator through the main control valve unit 10 for working, and at the same time, the return oil flow is detected through the flowmeter 17, when the return oil flow is less than the rated flow of the hydraulic oil radiator 20, the two-way cartridge valve one 18 is energized and the two-way cartridge valve two 19 is de-energized, and the return oil enters the hydraulic oil radiator 20 and returns to the hydraulic oil tank 1 through the two-way cartridge valve one 18; when the return oil flow is greater than the rated flow of the hydraulic oil radiator 20, the two-way cartridge valve one 18 and the two-way cartridge valve two 19 are both energized, and the excess return oil enters the hydraulic oil tank 1 through the two-way cartridge valve two 19.

Claims

1. An automatic cycle temperature rise, cooling system for excavators characterized by: The temperature sensor (29), the main pump unit, the main control valve unit (10), the controller (8), the circulating temperature rising unit, the power compensation unit, the auxiliary cooling unit, the oil return distribution unit and the circulating cooling unit are connected, the oil suction end of the main pump unit is connected with the hydraulic oil tank (1), the oil outlet end is connected with the oil inlet end of the main control valve unit (10), the circulating temperature rising unit and the auxiliary cooling unit, the oil return end of the main control valve unit (10) is connected with the oil inlet of the oil return distribution unit, the oil outlet of the distribution unit is connected with the circulating cooling unit, the auxiliary cooling unit supplies the stored energy to the circulating cooling unit, the oil outlet of the circulating cooling unit is connected with the hydraulic oil tank (1), the oil outlet of the circulating temperature rising unit is connected with the power compensation unit, the output end of the power compensation unit is connected with the input end of the main pump unit, the temperature sensor (29) collects the temperature of the hydraulic oil tank (1) and transmits it to the controller (8), the controller (8) is electrically connected with the main pump unit, the main control valve unit (10), the oil return distribution unit and the circulating cooling unit respectively; The main pump unit comprises the main pump one (3), the main pump two (4) and the pilot pump (2) coaxially connected with the engine (5); The circulating temperature rising unit comprises the working start valve (9), the confluence valve (11), the cartridge flow control valve (14), the switch valve (15) and the temperature rising opening valve (16), the oil outlets of the main pump one (3) are connected with the working start valve (9) and the temperature rising opening valve (16) respectively, the oil outlets of the main pump two (4) are connected with the working start valve (9) and the confluence valve (11) respectively, the oil outlets of the temperature rising opening valve (16) and the confluence valve (11) are connected with the oil inlets of the cartridge flow control valve (14) and the switch valve (15) respectively after confluence, and the oil outlet of the switch valve (15) is connected back to the hydraulic oil tank (1).

2. The excavator automatic cycle warm-up, cooling system of claim 1, wherein: The power compensation unit comprises the hydraulic motor (6) and the pressure compensation valve (7), the oil outlets of the temperature rising opening valve (16) and the confluence valve (11) are connected with the B port of the pressure compensation valve (7) after confluence, the oil outlet of the cartridge flow control valve (14) is connected with the P port of the pressure compensation valve (7), the A port of the pressure compensation valve (7) is connected with the oil inlet of the hydraulic motor (6), and the oil outlet of the hydraulic motor (6) is communicated with the hydraulic oil tank (1).

3. The excavator automatic cycle warm-up, cooling system of claim 1 or 2, characterized by: The oil return distribution unit comprises the flowmeter (17), the two-way cartridge valve one (18) and the two-way cartridge valve two (19), the oil return port of the main control valve unit (10) is connected with the flowmeter (17), the flowmeter (17) is connected with the oil inlets of the two-way cartridge valve one (18) and the two-way cartridge valve two (19) respectively, and the oil outlet of the two-way cartridge valve two (19) is connected with the hydraulic oil tank (1).

4. The excavator automatic cycle warm-up, cooling system of claim 3, wherein: The circulating cooling unit comprises a hydraulic oil radiator (20), a four-way electric proportional water valve (21), an oil return filter (24), a cooling water tank (25), a cooling water pump (26), a cooling motor (27) and a cooling pump (28), the oil outlet of the two-way cartridge valve one (18) is connected with the hydraulic oil tank (1) through the hydraulic oil radiator (20) and the oil return filter (24), the oil outlet of the cooling pump (28) is connected with the oil inlet of the cooling motor (27), the oil outlet of the cooling motor (27) is connected with the hydraulic oil tank (1), the cooling motor (27) is coaxially connected with the cooling water pump (26), the water suction port of the cooling water pump (26) is connected with the cooling water tank (25), the water outlet of the cooling water pump (26) is connected with the four-way electric proportional water valve (21), the outlet of the four-way electric proportional water valve (21) is respectively connected with the water inlet of the hydraulic oil radiator (20) and the cooling water tank (25), and the water outlet of the hydraulic oil radiator (20) is connected to the cooling water tank (25).

5. The excavator automatic cycle warm-up, cooling system of claim 4, wherein: The auxiliary cooling unit comprises an accumulator (12), a hydraulic control check valve (22) and a check valve two (23), the temperature rising opening valve (16) and the oil outlet of the merging valve (11) are further connected with the accumulator (12) through the check valve one (13), the check valve one (13) and the inlet of the accumulator (12) are connected with the oil inlet of the hydraulic control check valve (22) through a pipeline, and the oil outlet of the hydraulic control check valve (22) is connected with the oil outlet of the cooling pump (28) through the check valve two (23) and then merges into the oil inlet of the cooling motor (27).

6. A control method characterized by: The excavator automatic circulating temperature rising and cooling system comprises an automatic circulating heating mode, an oil return cooling mode and a working mode.

7. The control method according to claim 6, characterized in that: The operation method of the automatic circulating heating mode is as follows: After starting, the temperature sensor (29) detects the oil temperature of the hydraulic system and compares it with the temperature preset by the controller (8), assuming that the preset temperature is T1, T2 and T3, wherein T1 < T2 < T3, and the temperature between T2 and T3 is the ideal working temperature, when T1 < real-time temperature < T2, the working temperature does not meet the normal working temperature of the excavator, at this time, the working starting valve (9) is powered on, the on-off valve (15) is powered on, and the temperature rising opening valve (16) is powered on, the hydraulic oil output by the main pump one (3) enters the inlet of the cartridge type flow control valve (14), then the controller (8) outputs the current corresponding to the temperature of the hydraulic oil of the cartridge type flow control valve (14) through the relationship between the hydraulic oil temperature and the current, and outputs the final control current through the PID algorithm of the actual feedback current, so as to change the valve opening of the cartridge type flow control valve (14) and make the oil temperature rise, the heated oil enters the oil inlet of the hydraulic motor (6) through the pressure compensation valve (7) after heating, drives the motor to rotate, the hydraulic motor (6) is coaxially connected with the engine (5) to compensate the torque output of the engine (5), and at the same time, the hydraulic oil output by the main pump one (3) is stored in the accumulator (12) through the check valve one (13) during the circulating heating process, and the cooling pump (28) is in zero displacement.

8. The control method according to claim 6, characterized by: The operation method of the oil return cooling mode is as follows: When the real-time temperature > T3, the cooling pump (28) adjusts the displacement to a certain displacement, because the cooling pump (28) has a pressure oil output, a part of the pressure oil will open the hydraulic control check valve (22), so that the pressure oil stored in the accumulator (12) will drive the cooling motor (27) through the hydraulic control check valve (22), the check valve two (23) and the cooling pump (28) together, play the role of auxiliary cooling, at the same time reduce the energy output of the cooling pump (28), the cooling motor (27) provides power for the cooling water pump (26), the cooling water pump (26) sucks in cooling water from the cooling water tank (25), then passes through the four-way electric proportional water valve (21) into the water inlet of the hydraulic oil radiator (20) to cool the hydraulic oil; Because the real-time temperature > T3, that is, the temperature is higher than the ideal working temperature, in order to ensure that the hydraulic oil is cooled enough, the two-way cartridge valve two (19) loses power, the two-way cartridge valve one (18) gets power, and the oil return enters the hydraulic oil radiator (20) and returns to the hydraulic oil tank (1) through the two-way cartridge valve one (18).

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