An excavator implement oil return control system

Abstract

The present application provides a kind of excavator implement oil return control system, system includes: oil tank;Tool;Tool control valve, the tool control valve is communicated tool and main pump, for controlling the operation of tool;Main pump;Oil return control valve, inlet is communicated the outlet of tool control valve, outlet is communicated radiator and oil tank respectively, for according to the outlet pressure of tool control valve Switching position control to connect the oil return oil circuit of radiator or oil tank;When the outlet pressure of tool control valve is lower than preset value, oil return control valve switches oil return oil circuit and selects through radiator and returns oil tank;When the outlet pressure of tool control valve is higher than preset value, oil return control valve switches oil return oil circuit and selects not through radiator and directly returns oil tank;Radiator, one end is communicated oil return control valve, the other end is communicated oil tank, for the heat dissipation of oil liquid flowing through.The present application uses oil return control valve according to the outlet pressure of tool control valve Control to connect the loop of one-way valve pipeline, reduce oil return back pressure, protect tool, improve tool work efficiency.

Description

Technical Field

[0001] This invention belongs to the field of excavator hydraulic technology, specifically relating to an excavator implement return oil control system. Background Technology

[0002] Currently, there are two types of oil return systems for machinery, especially crushing machinery.

[0003] One solution is for the machine's return oil to be cooled by a radiator before returning to the oil tank, such as... Figure 1 As shown, the oil returned to the machine is cooled by the radiator system and then returns to the oil tank. This results in excessively high back pressure at the oil return end of the machine, affecting the machine's performance.

[0004] Another option is to have the machine's return oil line bypass the radiator and return directly to the oil tank, such as... Figure 2 As shown, the return oil from the machine does not flow through the radiator system for heat dissipation but returns directly to the oil tank. This causes excessive heat buildup in the oil tank during long-term operation, resulting in excessively high hydraulic oil temperature. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an excavator tool return oil control system that reduces return oil back pressure, protects the tool, and improves the tool's working efficiency.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] This invention provides an excavator implement return oil control system, comprising:

[0008] tank;

[0009] Machinery;

[0010] A tool control valve, which connects the tool and the main pump, is used to control the operation of the tool;

[0011] The main pump is connected to the oil tank at one end and to the machine control valve at the other end.

[0012] The return oil control valve has its inlet connected to the outlet of the tool control valve, and its outlet connected to the radiator and the oil tank respectively. It is used to switch the working position according to the outlet pressure of the tool control valve and control the connection of the return oil circuit to the radiator or the oil tank. When the outlet pressure of the tool control valve is lower than the preset value, the return oil control valve switches the return oil circuit to return to the oil tank through the radiator; when the outlet pressure of the tool control valve is higher than the preset value, the return oil control valve switches the return oil circuit to return directly to the oil tank without passing through the radiator.

[0013] The radiator, with one end connected to the oil return control valve and the other end connected to the oil tank, is used to dissipate heat from the flowing oil.

[0014] The above settings achieve the following effects: This application uses a return oil control valve to control the connection of the one-way valve pipeline according to the outlet pressure of the tool control valve. When the tool back pressure is low, the tool return oil circuit can be selected to return to the oil tank through the radiator; when the tool pressure is high, the tool return oil can be selected to return directly to the oil tank without passing through the radiator, which can reduce the return oil back pressure, protect the tool, and improve the tool working efficiency.

[0015] Furthermore, the return oil control valve is a hydraulically controlled three-position three-way valve; port 3 of the return oil control valve is connected to port P of the machine control valve, port 1 is connected to the radiator, and port 2 is connected to the oil tank; the pilot port of the return oil control valve is connected to port 3, which is used to switch the working position of the return oil control valve according to the pressure of port 3; the valve core of the return oil control valve has three working positions, namely right position, middle position and left position; in the non-working state, under the action of spring force, the valve core is in the left position;

[0016] When the pressure P at port 3 of the return oil control valve is less than P1, P1 is the set pressure. The hydraulic control force at the right end of the valve core of the return oil control valve is insufficient to overcome the spring force on the left side. At this time, the return oil control valve is in the left working position, and ports 3 and 1 are connected. The hydraulic oil at port T of the tool control valve passes through port 3 of the return oil control valve to port 1, and returns to the oil tank after being cooled by the radiator.

[0017] When the pressure P at port 3 of the return oil control valve satisfies P2 > P > P1, P2 is the second set pressure, the return oil control valve is in the neutral position, and ports 3, 1, and 2 are connected; in the neutral position, there is a throttling from port 3 to port 2, which causes the return oil hydraulic flow to return to the oil tank in two paths: one path returns directly to the oil tank; the other path returns to the oil tank after being cooled by the radiator.

[0018] When the pressure P at port 3 of the return oil control valve is greater than P2, the hydraulic force at the right end of the valve core of the return oil control valve overcomes the spring force on the left side, causing the control valve to be in the right working position, and ports 3, 1, and 2 are connected without throttling. At this time, the resistance of the oil circuit from port 1 back to the oil tank through the radiator is relatively large, so the return oil goes directly back to the oil tank through ports 3 and 1 of the return oil control valve.

[0019] The above settings achieve the following effects: Through the hydraulic control structure of the return oil control valve, the machine's return oil system achieves intelligent control based on the oil port pressure, which can automatically select the oil path, reduce the return oil back pressure, protect the machine, and improve the machine's working efficiency.

[0020] Furthermore, when the pressure at port 3 of the return oil control valve is P1, the outlet pressure at the return oil port of the implement reaches 90% of the maximum allowable back pressure value of the implement actuator.

[0021] When the pressure at port 3 of the return oil control valve is P2, the outlet pressure at the return oil port of the implement reaches the maximum allowable back pressure value of the implement actuator.

[0022] The above settings achieve the following effects: This setting helps to more accurately reduce the return oil back pressure, protect the machine, and improve the machine's working efficiency.

[0023] Furthermore, port 1 of the oil return control valve is connected to the radiator via a first check valve.

[0024] The above settings achieve the following effect: the first check valve can effectively prevent oil from flowing back from the radiator.

[0025] Further configuration: The oil return control system also includes:

[0026] A temperature sensor, installed in the oil tank, is used to collect the temperature of the hydraulic oil in the tank;

[0027] The cooling small circulation pumping system is connected to the oil tank at one end and to the radiator at the other end through a one-way valve, which is used to cool the oil in the oil tank.

[0028] The controller is connected to the temperature sensor and the cooling small circulation pumping system respectively, and is used to start the cooling small circulation pumping system when the temperature of the hydraulic oil in the oil tank exceeds the set value.

[0029] The above settings achieve the following effect: This invention adds a temperature sensor and a heat dissipation small circulation pump system and intelligently activates it to ensure that the entire hydraulic system operates at the optimal oil temperature.

[0030] Furthermore, the heat dissipation small circulation pumping system includes a motor connected to the controller and a gear pump connected to the motor;

[0031] The gear pump is connected to the inlet of the radiator via a check valve;

[0032] When the hydraulic oil temperature is greater than the set value T max When the controller receives a high temperature signal, it sends a signal to the motor of the heat dissipation small circulation pump system; the motor is powered on and drives the gear pump to pump the hot oil from the hydraulic oil tank to the radiator for heat dissipation.

[0033] The above settings achieve the following effect: the heat dissipation small circulation pumping system has a simple structure, is easy to implement, and is effectively adapted to the liquid circuit structure of this invention.

[0034] Furthermore, the gear pump is connected to the radiator via a second one-way valve.

[0035] The above settings achieve the following effect: the second check valve can effectively prevent the backflow of oil in the heat dissipation small circulation pumping system.

[0036] Furthermore, the machine control valve is a four-position three-way valve; its P port is connected to the main pump, and its T port is connected to the return oil control valve.

[0037] The machine control valve is equipped with two pilot ports for switching the direction of hydraulic oil.

[0038] The above settings achieve the following effect: When the machine is initially working, oil is supplied to port X1 or X2 of the machine control valve, and the pressure oil from the main pump enters port A / B of the machine through port P of the machine control valve, and the machine begins to work.

[0039] Furthermore, the oil return control system also includes:

[0040] A temperature sensor, installed in the oil tank, is used to collect the temperature of the hydraulic oil in the tank;

[0041] The solenoid valve is connected to the controller at one end, and to the main pump at the other end. It is used to connect or disconnect the main pump and the cooling small circulation pumping system according to the signal from the controller.

[0042] The controller is connected to the temperature sensor and the solenoid valve respectively. It is used to activate the solenoid valve to connect the main pump and the second cooling small circulation pumping system when the temperature of the hydraulic oil in the oil tank exceeds the set value.

[0043] The second cooling small circulation pumping system is connected to the oil tank, radiator and solenoid valve respectively. When the solenoid valve is connected, it pumps the oil in the oil tank into the radiator to cool the oil in the oil tank.

[0044] Furthermore, the second heat dissipation small circulation pumping system includes a motor connected between the oil tank and the main pump, and a gear pump driven by the motor; one end of the gear pump is connected to the oil tank and the other end is connected to the radiator, for pumping oil from the oil tank into the radiator.

[0045] The temperature sensor collects the temperature of the hydraulic oil in real time. When the hydraulic oil temperature exceeds the set value T... max When the controller receives a high temperature signal, it sends an electrical signal to the solenoid valve. The solenoid valve is energized and its valve core is pushed, connecting the main pump and the motor. The pressure oil from the main pump enters the motor of the cooling small circulation pumping system through the solenoid valve. The motor drives the gear pump to work, pumping the hot oil from the hydraulic oil tank to the radiator for cooling.

[0046] Furthermore, the temperature sensor collects the temperature of the hydraulic oil in real time. When the hydraulic oil temperature is lower than the second set value (T... max When the temperature reaches -X degrees Celsius, X is the set difference. The controller sends an electrical signal to the solenoid valve, causing the solenoid valve to lose power. The solenoid valve core is reset under the action of the spring, and the solenoid valve disconnects the main pump and motor. The oil supply to the motor of the heat dissipation small circulation pumping system is cut off, the motor stops running, and the gear pump stops working.

[0047] Furthermore, the outlet end of the gear pump is also connected to an overflow valve of the guide oil tank.

[0048] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0049] 1) The machine's oil return system is controlled and can automatically select the oil path to reduce the back pressure of the oil return, protect the machine, and improve the machine's working efficiency;

[0050] 2) This application adds a small circulation for cooling hydraulic oil and starts it based on oil temperature to ensure that the entire hydraulic system works at the optimal oil temperature. Attached Figure Description

[0051] Figure 1 This is a structural diagram of the existing scheme 1;

[0052] Figure 2 This is a structural diagram of the existing scheme 2;

[0053] Figure 3 This is a schematic diagram of the structure of the present invention;

[0054] Figure 4 This is a schematic diagram of another embodiment of the present application.

[0055] In the diagram: 1. Hydraulic oil tank; 2. Temperature sensor; 3. Main oil pump; 4. Tool control valve; 5. Tool; 6. Controller; 7. Cooling small circulation pumping system; 8. Return oil control valve; 9. Check valve (including 9-1, first check valve; 9-2, second check valve); 10. Radiator; X1 / X2, pilot oil port of tool control valve; 11. Solenoid valve; 12. Second cooling small circulation pumping system; 13. Relief valve. Detailed Implementation

[0056] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0057] In the description of this embodiment, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment.

[0058] Example 1:

[0059] This embodiment provides an excavator implement return oil control system. The hydraulic schematic diagram of the implement return oil pipeline control system is attached. Figure 3 The detailed process is as follows.

[0060] In the working mode of the tool, when the tool is initially working, oil is supplied to port X1 or X2 of the tool control valve 4, and the pressure oil of the main pump 3 enters port A / B of the tool 5 (the actuator can be a motor, a cylinder or other actuator, which is shown as a motor in the figure) through port P of the control valve 4, and the tool starts to work.

[0061] When the pressure P at port 3 of the return oil control valve 8 is less than P1 (P1 is the set pressure), the hydraulic control force at the right end of the valve core of the return oil control valve 8 is insufficient to overcome the spring force on the left side. At this time, the return oil control valve 8 is in the left working position. The hydraulic oil at port T passes through port 3 of the return oil control valve to port 1, then through check valve 9-1, and finally returns to the hydraulic oil tank 1 after being cooled by radiator 10.

[0062] Temperature sensor 2 operates in real time, transmitting the detected signals to the controller.

[0063] The valve core of the return oil control valve 8 has three working positions: right position, middle position and left position. In the non-working state, the valve core is in the left position under the action of spring force.

[0064] When the pressure at port 3 is P1, the outlet pressure at the return oil port of the implement reaches 90% of the maximum allowable back pressure value of the implement actuator; when the pressure at port 3 is P2, the outlet pressure at the return oil port of the implement reaches the maximum allowable back pressure value of the implement actuator.

[0065] When the pressure P at port 3 of the return oil control valve 8 satisfies P2 > P > P1, P1 and P2 are the set pressures, the return oil control valve 8 is in the neutral position, and ports 3, 1 and 2 are connected; in the neutral position, there is a throttling from port 3 to port 2, which causes the return oil hydraulic flow to return to the oil tank in two ways; one way returns directly to the oil tank; the other way passes through check valve 9-1, and finally returns to the hydraulic oil tank 1 after being cooled by radiator 10; at this time, the machine return oil system takes into account both the return oil back pressure and the hydraulic oil cooling.

[0066] The purpose of setting the throttle orifice is to allow the main return oil to pass through two return oil paths: one path goes through the radiator, which has a larger pressure loss (i.e., a larger back pressure); the other path goes directly back to the oil tank, which has a smaller pressure loss (i.e., a smaller back pressure). In order to balance the pressure of the two paths and make the back pressure values ​​of the two paths similar, the path with the smaller back pressure value is throttled. The size of the throttle orifice is related to the model of the machine and the back pressure values ​​from the two self-return oil control valves to the oil tank, and needs to be determined by actual measurement.

[0067] When the pressure P at port 3 of the return oil control valve 8 continues to rise, and P > P2 (P2 is the set pressure), the hydraulic control force at the right end of the valve core of the return oil control valve 8 overcomes the spring force on the left side, causing the control valve to be in the right working position. At this time, since the resistance of the oil circuit from port 1 to the oil tank via radiator 10 is relatively large, the return oil from port T returns directly to the oil tank 1 via port 3 and port 1 of the pressure-controlled directional valve.

[0068] Preferably, the oil return control system further includes:

[0069] Temperature sensor 2 is installed in the oil tank to collect the temperature of the hydraulic oil in the tank;

[0070] The cooling small circulation pumping system 7 is connected to the oil tank at one end and to the radiator at the other end through a one-way valve, and is used to cool the oil in the oil tank.

[0071] The controller 6 is connected to the temperature sensor 2 and the cooling small circulation pumping system 7 respectively, and is used to start the cooling small circulation pumping system 7 when the temperature of the hydraulic oil in the oil tank exceeds the set value.

[0072] This invention adds a temperature sensor 2 and a heat dissipation small circulation pump system 7 and intelligently activates them to ensure that the entire hydraulic system operates at the optimal oil temperature.

[0073] The heat dissipation small circulation pumping system 7 includes a motor connected to the controller 6 and a gear pump connected to the motor;

[0074] The gear pump is connected to the inlet of the radiator via a check valve;

[0075] When the hydraulic oil temperature exceeds the set value Tmax, the controller 6 receives a high-temperature signal and sends a signal to the motor of the cooling small circulation pumping system 7. The motor is energized and drives the gear pump to pump the hot oil from the hydraulic oil tank 1 to the radiator for cooling. The cooling small circulation pumping system 7 has a simple structure, is easy to implement, and is effectively adapted to the hydraulic circuit structure of this invention.

[0076] The gear pump is connected to the radiator via a second check valve 9-2. The second check valve 9-2 effectively prevents backflow of oil within the radiator's small circulation pumping system 7.

[0077] When the excavator is operating, the hydraulic oil returns directly to the oil tank without passing through the radiator. After a period of time, the hydraulic oil in the tank will accumulate significant heat, leading to overheating. Temperature sensor 2 collects the hydraulic oil temperature in real time. When the hydraulic oil temperature exceeds the set value T... max When the controller 6 receives a high temperature signal (as determined by the hydraulic oil used and the hydraulic system requirements), it sends a signal to the motor of the cooling small circulation pumping system 7. The motor is powered on and drives the gear pump of the pumping component 7 to work, pumping the hot oil from the hydraulic oil tank to the radiator 11 for cooling. That is, the hydraulic oil cooling small circulation system starts to work.

[0078] Example 2:

[0079] This embodiment provides an excavator implement return oil control system, such as... Figure 4 As shown, the difference between this and Embodiment 1 is that the oil return control system further includes:

[0080] Temperature sensor 2 is installed in oil tank 1 to collect the temperature of hydraulic oil in oil tank 1;

[0081] The solenoid valve is connected to the controller 6 at one end, and to the main pump at the other end. It is used to connect or disconnect the main pump and the cooling small circulation pumping system according to the signal from the controller 6.

[0082] The controller 6 is connected to the temperature sensor 2 and the solenoid valve respectively, and is used to start the main pump and the second cooling small circulation pumping system when the temperature of the hydraulic oil in the oil tank 1 exceeds the set value.

[0083] The second cooling small circulation pumping system 11 is connected to the oil tank 1, the radiator and the solenoid valve respectively. When the solenoid valve is connected, it pumps the oil in the oil tank 1 into the radiator to cool the oil in the oil tank 1.

[0084] The second heat dissipation small circulation pumping system 11 includes a motor connected between the oil tank 1 and the main pump, and a gear pump driven by the motor; one end of the gear pump is connected to the oil tank 1, and the other end is connected to the radiator, for pumping the oil in the oil tank 1 into the radiator.

[0085] The gear pump is connected to the radiator via a second check valve 9-2. The second check valve 9-2 effectively prevents backflow of oil within the radiator's small circulation pumping system 7.

[0086] When the excavator implement 5 is working, the return oil from implement 5 goes directly back to the oil tank 1 without passing through the radiator. After a period of time, the hydraulic oil in the oil tank 1 will accumulate severe heat, leading to the problem of hydraulic oil overheating.

[0087] Temperature sensor 2 collects the temperature of hydraulic oil in real time. When the hydraulic oil temperature is greater than the set value Tmax (determined by the hydraulic oil used and the hydraulic system requirements), controller 6 receives a high temperature signal and sends an electrical signal to solenoid valve 11. The solenoid valve is energized and the valve core is pushed, and ports 1 and 2 of solenoid valve 11 are connected. The pressure oil from main pump 3 enters the motor of cooling small circulation pumping system 12 through ports 1 and 2 of solenoid valve 11. The motor drives the gear pump of cooling small circulation pumping system 12 to work, pumping the hot oil from hydraulic oil tank 1 to radiator 11 for heat dissipation. That is, the hydraulic oil cooling small circulation system starts to work.

[0088] After the second cooling small circulation pumping system has been working for a period of time, when the hydraulic oil temperature is lower than the second set value (Tmax-X) degrees Celsius (X can be set according to the situation, generally selected as 5), the controller 6 sends an electrical signal to the solenoid valve 11, causing the solenoid valve 11 to be de-energized, the solenoid valve core to be reset under the action of the spring, and the 1 port and 2 port of the solenoid valve 11 to be disconnected; the motor oil supply of the cooling small circulation pumping system 12 is cut off, the motor stops running, that is, the hydraulic oil cooling small circulation system stops working.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0090] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0091] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0092] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0093] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A return oil control system for excavator implements, characterized in that, include: tank; Machinery; A tool control valve, which connects the tool and the main pump, is used to control the operation of the tool; The main pump is connected to the oil tank at one end and to the machine control valve at the other end. The return oil control valve has its inlet connected to the outlet of the tool control valve, and its outlet connected to the radiator and the oil tank respectively. It is used to switch the working position according to the outlet pressure of the tool control valve and control the connection of the return oil circuit to the radiator or the oil tank. When the outlet pressure of the tool control valve is lower than the preset value, the return oil control valve switches the return oil circuit to return to the oil tank through the radiator; when the outlet pressure of the tool control valve is higher than the preset value, the return oil control valve switches the return oil circuit to return directly to the oil tank without passing through the radiator. The radiator, with one end connected to the return oil control valve and the other end connected to the oil tank, is used to dissipate heat from the flowing oil. The return oil control valve is a hydraulically controlled three-position three-way valve; port 3 of the return oil control valve is connected to port P of the machine control valve, port 1 is connected to the radiator, and port 2 is connected to the oil tank; the pilot port of the return oil control valve is connected to port 3, which is used to switch the working position of the return oil control valve according to the pressure of port 3; the valve core of the return oil control valve has three working positions, namely right position, middle position and left position; in the non-working state, under the action of spring force, the valve core is in the left position; When the pressure P at port 3 of the return oil control valve is less than P1, P1 is the set pressure. The hydraulic control force at the right end of the valve core of the return oil control valve is insufficient to overcome the spring force on the left side. At this time, the return oil control valve is in the left working position, and ports 3 and 1 are connected. The hydraulic oil at port T of the tool control valve passes through port 3 of the return oil control valve to port 1, and returns to the oil tank after being cooled by the radiator. When the pressure P at port 3 of the return oil control valve satisfies P2 > P > P1, P2 is the second set pressure, the return oil control valve is in the neutral position, and ports 3, 1, and 2 are connected; in the neutral position, there is a throttling from port 3 to port 2, which causes the return oil hydraulic flow to return to the oil tank in two paths: one path returns directly to the oil tank; the other path returns to the oil tank after being cooled by the radiator. When the pressure P at port 3 of the return oil control valve is greater than P2, the hydraulic force at the right end of the valve core of the return oil control valve overcomes the spring force on the left side, causing the control valve to be in the right working position, and ports 3, 1, and 2 are connected without throttling. At this time, the resistance of the oil circuit from port 1 back to the oil tank through the radiator is relatively large, so the return oil goes directly back to the oil tank through ports 3 and 1 of the return oil control valve.

2. The excavator implement return oil control system according to claim 1, characterized in that, When the pressure at port 3 of the return oil control valve is P1, the outlet pressure at the return oil port of the implement reaches 90% of the maximum allowable back pressure value of the implement actuator. When the pressure at port 3 of the return oil control valve is P2, the outlet pressure at the return oil port of the implement reaches the maximum allowable back pressure value of the implement actuator.

3. The excavator implement return oil control system according to claim 1, characterized in that, One port of the oil return control valve is connected to the radiator via a first check valve.

4. The excavator implement return oil control system according to claim 1, characterized in that, The oil return control system also includes: A temperature sensor, installed in the oil tank, is used to collect the temperature of the hydraulic oil in the tank; The cooling small circulation pumping system is connected to the oil tank at one end and to the radiator at the other end, and is used to cool the oil in the oil tank. The controller is connected to the temperature sensor and the cooling small circulation pumping system respectively, and is used to start the cooling small circulation pumping system when the temperature of the hydraulic oil in the oil tank exceeds the set value.

5. The excavator implement return oil control system according to claim 4, characterized in that, The heat dissipation small circulation pumping system includes a motor connected to the controller and a gear pump connected to the motor; The gear pump is connected to the inlet of the radiator via a first check valve; When the hydraulic oil temperature is greater than the set value T max When the controller receives a high temperature signal, it sends a signal to the motor of the heat dissipation small circulation pump system; the motor is powered on and drives the gear pump to pump the hot oil from the hydraulic oil tank to the radiator for heat dissipation.

6. The excavator implement return oil control system according to claim 5, characterized in that, The gear pump is connected to the radiator via a second one-way valve.

7. The excavator implement return oil control system according to claim 1, characterized in that, The machine control valve is a four-position three-way valve; its P port is connected to the main pump, and its T port is connected to the return oil control valve. The machine control valve is equipped with two pilot ports for switching the direction of hydraulic oil.

8. The excavator implement return oil control system according to claim 1, characterized in that, The oil return control system also includes: A temperature sensor, installed in the oil tank, is used to collect the temperature of the hydraulic oil in the tank; The solenoid valve is connected to the controller at one end, and to the main pump at the other end. It is used to connect or disconnect the main pump and the cooling small circulation pumping system according to the signal from the controller. The controller is connected to the temperature sensor and the solenoid valve respectively. It is used to activate the solenoid valve to connect the main pump and the second cooling small circulation pumping system when the temperature of the hydraulic oil in the oil tank exceeds the set value. The second cooling small circulation pumping system is connected to the oil tank, radiator and solenoid valve respectively. When the solenoid valve is connected, it pumps the oil in the oil tank into the radiator to cool the oil in the oil tank. The second heat dissipation small circulation pumping system includes a motor connected between the oil tank and the main pump, and a gear pump driven by the motor; one end of the gear pump is connected to the oil tank and the other end is connected to the radiator, and is used to pump the oil in the oil tank into the radiator; The temperature sensor collects the temperature of the hydraulic oil in real time. When the hydraulic oil temperature exceeds the set value T... max When the controller receives a high temperature signal, it sends an electrical signal to the solenoid valve. The solenoid valve is energized and its valve core is pushed, connecting the main pump and the motor. The pressure oil from the main pump enters the motor of the cooling small circulation pumping system through the solenoid valve. The motor drives the gear pump to work, pumping the hot oil from the hydraulic oil tank to the radiator for cooling.

9. The excavator implement return oil control system according to claim 1, characterized in that, The temperature sensor collects the temperature of the hydraulic oil in real time. When the hydraulic oil temperature is lower than the second set value (T), max When the temperature reaches -X degrees Celsius, X is the set difference. The controller sends an electrical signal to the solenoid valve, causing the solenoid valve to lose power. The solenoid valve core is reset under the action of the spring, and the solenoid valve disconnects the main pump and the motor. The oil supply to the motor of the heat dissipation small circulation pumping system is cut off, the motor stops running, and the gear pump stops working.

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