Work machine hydraulic control system, method, and work machine

Abstract

The application relates to the technical field of hydraulic systems, and discloses a work machine hydraulic control system, a work machine hydraulic control method and a work machine. The bypass oil return system of the hydraulic control system comprises the following: a first bypass circuit, a first end of which is connected to a first main oil path close to a hydraulic cylinder, and a second end of which is connected to a second main oil path close to a main reversing valve; the first bypass circuit is sequentially provided with a first pressure opening valve, an electromagnetic opening valve and a second pressure opening valve in the direction from the first end to the second end, and the electromagnetic opening valve is electrically connected to an electric control handle; a second bypass circuit, one end of which is connected to the second main oil path close to the hydraulic cylinder, and the other end of which is connected to the first pressure opening valve; and an oil return path, one end of which is connected to the second main oil path between the first bypass circuit and the second bypass circuit, and the other end of which is connected to an oil tank. Therefore, when the rod cavity is filled with oil and the rodless cavity returns oil, the valve group is opened, the oil return flow enters the oil return path from the valve group, the oil return amount can be quickly discharged, the back pressure is reduced, and the speed of the rod cavity contraction is increased.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, specifically to hydraulic control systems, methods, and machinery for use. Background Technology

[0002] Currently, the main approach for high-flow hydraulic systems is to develop large multi-way valves with larger valve cores to meet both inlet and outlet flow requirements. However, this approach suffers from high development costs, long development cycles, significant technical challenges, poor availability of spare parts, and high spare parts costs, preventing the mature application of larger-scale main pumps and valves. Summary of the Invention

[0003] In view of this, the present invention provides a hydraulic control system for operating machinery to solve the problems of the failure to maturely apply the use of larger valve cores, high development costs, and long development cycles.

[0004] In a first aspect, the present invention provides a hydraulic control system for a working machine, wherein the working machine includes a hydraulic cylinder, an electric control handle, a main directional valve, and an oil tank. The rod-side chamber of the hydraulic cylinder is connected to the oil tank via a first main oil circuit, and the rodless chamber of the hydraulic cylinder is connected to the oil tank via a second main oil circuit. Both the first and second main oil circuits pass through the main directional valve. The electric control handle is used to send a signal to the main directional valve indicating whether the hydraulic cylinder is extended or retracted. The hydraulic control system includes a bypass return oil system, which comprises:

[0005] The first bypass circuit has a first end connected to the first main oil circuit near the hydraulic cylinder, and a second end connected to the second main oil circuit near the main directional valve. The first bypass circuit is provided with a first pressure opening valve, a solenoid opening valve and a second pressure opening valve in sequence from the first end to the second end. The solenoid opening valve is electrically connected to the electric control handle.

[0006] The second bypass circuit has one end connected to the second main oil circuit near the hydraulic cylinder, and the other end connected to the first pressure opening valve.

[0007] The return oil circuit is connected to the second main oil circuit at one end and to the oil tank at the other end.

[0008] Beneficial effects: By adding a bypass return oil system to this solution and adding a valve group at the return oil line, when oil enters the rod chamber and returns oil to the rodless chamber, the valve group is opened, and the return oil flow enters the return oil line from the valve group, which can quickly discharge the return oil, reduce back pressure, and accelerate the contraction speed of the rod chamber.

[0009] In one alternative embodiment, the second pressure opening valve is provided with an oil discharge port that satisfies the maximum flow rate of oil returning from the rodless chamber of the hydraulic cylinder.

[0010] Beneficial effect: Because the second pressure opening valve is designed with an oil discharge hole that meets the maximum flow rate of oil return from the rodless chamber, the maximum flow rate requirement of oil return from the rodless chamber can be met after the second pressure opening valve is opened.

[0011] In one optional embodiment, the first pressure-opening valve, the electromagnetic opening valve, and the second pressure-opening valve are all provided with a valve port and a valve core that is movably disposed at the valve port by a spring.

[0012] Beneficial effect: The valve core can then automatically open or close under pressure.

[0013] In one optional embodiment, the opening pressure of the first pressure-opening valve is not less than 0.5 MPa.

[0014] Beneficial effect: In other words, the first pressure opening valve only opens when the pressure reaches 0.5MPa, thus preventing cavitation.

[0015] In an optional embodiment, it further includes:

[0016] The return oil throttling speed control system includes an electro-proportional opening valve and a throttle valve. The electro-proportional opening valve is located on the return oil line between the oil tank and the second pressure opening valve. The throttle valve is located on the second main oil line between the main directional valve and the electro-proportional opening valve. The second main oil line is connected to the electro-proportional opening valve.

[0017] A first position sensor and a second position sensor, wherein the first position sensor is located at the buffer position of the rod-side chamber of the hydraulic cylinder, and the second position sensor is located at the buffer position of the rodless chamber of the hydraulic cylinder;

[0018] The controller is electrically connected to the first position sensor and the second position sensor, and electrically connected to the throttle valve and the electro-proportional opening valve, respectively. The controller is used to control the throttle valve and the electro-proportional opening valve to open for throttling based on the signal detected by the first position sensor or the second position sensor.

[0019] Beneficial effects: By adjusting the speed through return oil throttling, the pressure shock generated when the hydraulic cylinder exits the buffer zone can be effectively avoided, which can effectively increase the operational stability when using the hydraulic cylinder.

[0020] In an optional embodiment, a return oil branch is further included, one end of which is connected to the electro-proportional opening valve, and the other end is connected to the return oil circuit between the electro-proportional opening valve and the oil tank. A pressure delay valve is provided on the return oil branch.

[0021] Beneficial effects: After the hydraulic cylinder leaves the buffer zone, the controller sends a zero signal to the electro-proportional opening valve, the throttle valve closes, and the oil on the left side of the electro-proportional opening valve can only return to the oil tank through the pressure delay valve. The delay effect of the pressure delay valve causes the pressure on the left side of the electro-proportional opening valve to decrease slowly, and the throttle port becomes a normally open port after a delay. This avoids the shock caused by the electro-proportional opening valve signal suddenly changing from fully open to zero, causing the valve core to open instantaneously as a straight-through valve core, and the rapid decrease in back pressure.

[0022] Secondly, the present invention also provides a hydraulic control method for a work machinery, applied to the aforementioned hydraulic control system of the work machinery, comprising the following steps:

[0023] In response to the oil inlet operation of the rod chamber of the hydraulic cylinder, the first pressure opening valve opens under pressure.

[0024] The electromagnetic opening valve opens upon receiving an electrical signal from the electric control handle;

[0025] The second pressure opening valve compares the magnitude of the inlet oil pressure and the return oil pressure, and opens when the inlet oil pressure is greater than the return oil pressure.

[0026] The return oil from the rodless chamber of the hydraulic cylinder enters the return oil circuit through the second pressure opening valve, causing the back pressure of the return oil from the rodless chamber of the hydraulic cylinder to decrease.

[0027] Beneficial effects: It ensures that the second pressure opening valve in the bypass return oil system only opens when the inlet oil pressure is greater than the return oil pressure, thereby reducing the return oil back pressure and allowing the stick, bucket and other moving parts to unload quickly.

[0028] In an optional embodiment, the step further includes:

[0029] The range of the output signal after controller processing is set to 0-c, where c>1;

[0030] The electro-proportional valve is fully closed when it receives a signal of 0, fully open when it receives a signal of c, and opens proportionally when it receives a signal between 0 and c.

[0031] When the throttle valve receives a signal from the controller and anticipates that the piston of the hydraulic cylinder is about to leave the buffer zone, the throttle valve and the electro-proportional opening valve are fully opened, and the oil enters the electro-proportional opening valve through the throttle valve. At this time, the throttle is fully open, and the resulting back pressure cancels out the impact of entering the buffer zone.

[0032] Beneficial effects: By using the electrical signal of the buffer zone position and the control signal of the operating handle to throttle the return oil, the pressure of the hydraulic cylinder will be limited when leaving the buffer zone.

[0033] In one alternative embodiment, the controller's processed output signal is obtained by processing the position sensor signal and the electric handle opening ratio signal.

[0034] Thirdly, the present invention also provides a working machine, comprising:

[0035] The hydraulic cylinder comprises a hydraulic cylinder, an electric control handle, a main directional valve, and an oil tank. The rod chamber of the hydraulic cylinder is connected to the oil tank through a first main oil circuit, and the rodless chamber of the hydraulic cylinder is connected to the oil tank through a second main oil circuit. The first main oil circuit and the second main oil circuit both pass through the main directional valve. The electric control handle is used to send a signal to the main directional valve to extend or retract the hydraulic cylinder.

[0036] The hydraulic control system of the aforementioned working machinery is located between the first main oil circuit and the second main oil circuit.

[0037] Beneficial effects: The first pressure opening valve determines whether there is pressure in the return oil line, and the bypass return oil system is not opened when the oil line is sucked in; the solenoid opening valve determines whether the electric control handle is in the rod chamber oil inlet operation, and it is only opened when the electric control handle is in the rod chamber oil inlet operation condition.

[0038] When both the first pressure opening valve and the solenoid opening valve are open, the magnitudes of the return oil pressure and the inlet oil pressure are compared. When the second pressure opening valve is opened by the pressure of the rod chamber of the hydraulic cylinder, most of the return oil from the rodless chamber enters the return oil circuit through the second pressure opening valve, thus reducing back pressure during return oil flow. To address the impact caused by sudden changes in flow rate when the hydraulic cylinder enters and exits the buffer zone, a throttle valve and an electro-proportional control valve are added to the return oil circuit to control the return oil back pressure and reduce the impact caused by the hydraulic cylinder leaving the buffer zone. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the hydraulic control system of a work machinery according to an embodiment of the present invention;

[0041] Figure 2 A schematic diagram showing the excavator in the state of unloading the boom;

[0042] Figure 3 A schematic diagram showing the excavator in the state of unloading the bucket;

[0043] Figure 4 A schematic diagram showing the excavator in the boom-lowered position;

[0044] Figure 5This is a schematic diagram of an excavator in a position where the stick is resisting gravity.

[0045] Figure 6 This is a schematic diagram of an excavator in a position where the bucket is resisting gravity.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. First pressure opening valve; 2. Solenoid opening valve; 3. Second pressure opening valve; 4. Main directional valve; 5. Throttle valve; 6. Electro-proportional opening valve; 7. Pressure delay valve; 8. Oil tank; 9. First position sensor; 10. Second position sensor; 11. Hydraulic cylinder; 12. First bypass circuit; 13. Second bypass circuit; 14. Return oil circuit; 15. First main oil circuit; 16. Second main oil circuit. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In high-flow hydraulic systems using directional valves, due to the large base flow rate of the inlet oil, when oil enters the rod chamber and returns to the rodless chamber of the hydraulic cylinder, the return oil flow rate is A1 (rodless chamber area) / A2 (rod chamber area) times the inlet flow rate because of the area difference between the rod and rodless chambers. The maximum return oil flow rate of the valve core cannot meet the cylinder's return oil demand, resulting in high back pressure in the return oil system and reduced operating speed. To solve the above technical problems, this invention provides a hydraulic control system for operating machinery.

[0050] Understandably, the operating machinery mainly includes hydraulic cylinders, electric control handles, main directional valves, and oil tanks. The rod chamber of the hydraulic cylinder is connected to the oil tank through the first main oil circuit, and the rodless chamber of the hydraulic cylinder is connected to the oil tank through the second main oil circuit. The first and second main oil circuits both pass through the main directional valve, which is used for reversing the piston by allowing oil to enter the rod chamber and return oil to the rodless chamber, or by allowing oil to return oil to the rod chamber and enter oil to the rodless chamber, thus extending the piston. The electric control handle is used to send a signal to the main directional valve to extend or retract the hydraulic cylinder. In other words, the operation signal of the electric control handle is sent to the main directional valve to open the corresponding oil circuit.

[0051] The following is combined with Figure 1 The following describes embodiments of the present invention.

[0052] According to an embodiment of the present invention, in one aspect, a hydraulic control system for a working machine is provided, wherein the hydraulic control system includes a bypass return oil system, which is activated when oil is supplied to the rod chamber and returned to the rodless chamber, and when the return oil back pressure is high. When oil is supplied to the rodless chamber and returned to the rod chamber, the bypass return oil system does not operate, and only the main directional valve 4 operates.

[0053] Specifically, the bypass return oil system includes:

[0054] The first bypass circuit 12 has two ends, namely the first end and the second end. The first end is connected to the first main oil circuit 15 near the hydraulic cylinder 11, and the second end is connected to the second main oil circuit 16 near the main reversing valve 4. The first bypass circuit 12 is provided with a first pressure opening valve 1, a solenoid opening valve 2 and a second pressure opening valve 3 in sequence from the first end to the second end. The solenoid opening valve 2 is electrically connected to the electric control handle.

[0055] The second bypass circuit 13 is connected at one end to the second main oil circuit 16 near the hydraulic cylinder 11, and at the other end to the first pressure opening valve 1.

[0056] The return oil line 14 connects to the second main oil line 16 at one end and to the oil tank 8 at the other end. Figure 1 Taking the indicated orientation as an example, when the electric control handle retracts the hydraulic cylinder 11, the main directional valve 4 receives a signal and moves to the left. The pressurized oil in the hydraulic system enters from port P and passes through the main directional valve 4 into the rod chamber. At the same time, the oil in the rodless chamber is forced into the second bypass circuit 13. The back pressure generated in the second bypass circuit 13 causes the oil to enter the left side of the first pressure opening valve 1 (in the original state, the first pressure opening valve 1 is unable to pass through because the valve core is pushed to the left by the preloaded spring). This pushes the valve core of the first pressure opening valve 1 from the left to the right, opening it. The solenoid opening valve 2 receives an electrical signal controlled by the electric control handle and pushes the valve core to the right, opening it. The pressurized oil entering the rod chamber of the hydraulic cylinder 11 is opened by the first pressure opening valve 1 and the solenoid opening valve 2, and the oil enters the left side of the second pressure opening valve 3. The hydraulic oil coming out of the rodless chamber enters the right side of the second pressure opening valve 3. Since the inlet oil pressure is greater than the return oil pressure, the valve core of the second pressure opening valve 3 is pushed to the right side and opened. Part of the hydraulic oil coming out of the rodless chamber returns to the oil tank 8 through the main reversing valve 4, and the other part returns to the oil tank 8 through the valve core opened by the second pressure opening valve 3. The hydraulic oil is quickly discharged through the valve core opened by the second pressure opening valve 3, which reduces the back pressure caused by the inability to discharge quickly during the return oil flow and accelerates the contraction speed of the rod chamber.

[0057] In a hydraulic system using hydraulic cylinder 11, when the working state is that the rod chamber is receiving oil and the rodless chamber is returning oil, the return oil flow rate will be much greater than the inlet oil flow rate due to the area difference between the rod chamber and the rodless chamber. Conventional directional valves cannot effectively solve the problem of a large amount of return oil from the rodless chamber, resulting in high return oil back pressure and slow working speed. By adding a bypass return oil system in this embodiment, a valve group is added at the return oil line 14. When the rod chamber is receiving oil and the rodless chamber is returning oil, the valve group is opened, and the return oil flow rate enters the return oil line 14 from the valve group, which can quickly discharge the return oil, reduce back pressure, and accelerate the contraction speed of the rod chamber.

[0058] In one specific embodiment, the second pressure opening valve 3 is provided with an oil discharge port that meets the maximum flow rate of oil return from the rodless chamber of the hydraulic cylinder 11. Because the second pressure opening valve 3 is designed with an oil discharge port that meets the maximum flow rate of oil return from the rodless chamber, the maximum flow rate requirement of oil return from the rodless chamber can be met after the second pressure opening valve 3 is opened.

[0059] In one specific embodiment, the first pressure-opening valve 1, the solenoid-opening valve 2, and the second pressure-opening valve 3 are all provided with valve ports and valve cores that are movably disposed at the valve ports by a spring. Thus, the valve cores can automatically open or close under pressure. For example, in this embodiment, the second pressure-opening valve 3 opens when the inlet oil pressure is greater than the return oil pressure and closes when the inlet oil pressure is less than the return oil pressure. The solenoid-opening valve 2 can open under the action of an electrical signal from the electric control handle and close when the electrical signal is disconnected.

[0060] In one specific embodiment, the opening pressure of the first pressure-opening valve 1 is not less than 0.5 MPa. That is, the first pressure-opening valve 1 only opens when the pressure reaches 0.5 MPa, thereby preventing cavitation.

[0061] In one specific embodiment, the hydraulic control system further includes:

[0062] The return oil throttling speed control system includes an electro-proportional opening valve 6 and a throttle valve 5. The electro-proportional opening valve 6 is located on the return oil passage 14 between the oil tank 8 and the second pressure opening valve 3. The throttle valve 5 is located on the second main oil passage 16 between the main directional valve 4 and the electro-proportional opening valve 6. The second main oil passage 16 is connected to the electro-proportional opening valve 6.

[0063] The first position sensor 9 and the second position sensor 10 are located in the buffer zone of the rod chamber of the hydraulic cylinder 11, and the second position sensor 10 is located in the buffer zone of the rodless chamber of the hydraulic cylinder 11. It can be understood that the buffer zone positions can be pre-calibrated, and then the first position sensor 9 and the second position sensor 10 are set in the corresponding buffer zone positions.

[0064] The controller is electrically connected to the first position sensor 9 and the second position sensor 10, as well as to the throttle valve 5 and the electro-proportional opening valve 6. The controller controls the throttle valve 5 and the electro-proportional opening valve 6 to open and throttle based on the signal detected by the first position sensor 9 or the second position sensor 10, which indicates that the piston of the hydraulic cylinder 11 is located in the buffer zone of the rod chamber or the buffer zone of the rodless chamber. By adjusting the speed through return oil throttling, pressure shocks generated when the hydraulic cylinder 11 exits the buffer zone can be effectively avoided, thus effectively increasing the operational stability of the cylinder.

[0065] In one specific embodiment, a return oil branch is also included. One end of the return oil branch is connected to the electro-proportional opening valve 6, and the other end is connected to the return oil passage 14 between the electro-proportional opening valve 6 and the oil tank 8. A pressure delay valve 7 is provided on the return oil branch. Specifically, after the hydraulic cylinder 11 leaves the buffer zone, the signal from the controller to the electro-proportional opening valve 6 is zero, the throttle valve 5 is closed, and the oil on the left side of the electro-proportional opening valve 6 can only return to the oil tank 8 through the pressure delay valve 7. The delay effect of the pressure delay valve 7 causes the pressure on the left side of the electro-proportional opening valve 6 to decrease slowly, and the throttle port becomes a normally open port after the delay. This avoids the impact caused by the signal of the electro-proportional opening valve 6 suddenly changing from fully open to zero, causing the valve core to open instantly to a straight-through valve core, and the rapid decrease in back pressure.

[0066] In a specific application scenario, when hydraulic cylinder 11 is used on an excavator, the state of oil intake in the rod chamber and oil return in the rodless chamber corresponds to three operations: stick unloading, bucket unloading, and boom lowering. When the excavator is in any of these three operations... Figure 2 , Figure 3 , Figure 4 Under the movement, the first pressure opening valve 1 opens under the return oil pressure, and the solenoid opening valve 2 opens under the operation signal of the electric control handle. At this time, the second pressure opening valve 3 will not open because the return oil back pressure is greater than the inlet oil pressure due to the influence of the working device's own weight under the above three working conditions. The opening logic of the second pressure opening valve 3 ensures that the working device will not lose back pressure due to the opening of the bypass return oil system during the three operations of stick unloading, bucket unloading, and boom lowering, thus preventing the working device from stalling and falling. When the stick and bucket move to a state that resists gravity, such as... Figure 5 , Figure 6 At the same time, the inlet oil pressure needs to resist gravity. At this time, the inlet oil pressure is greater than the return oil pressure. The second pressure opening valve 3 in the bypass return oil system opens to reduce the return oil back pressure, so that the stick and bucket can be unloaded quickly.

[0067] On the other hand, the present invention also provides a hydraulic control method for operating machinery, applied to the aforementioned hydraulic control system of operating machinery, comprising the following steps:

[0068] In response to the oil inlet operation of the rod chamber of the hydraulic cylinder 11, the first pressure opening valve 1 opens under pressure.

[0069] The electromagnetic opening valve 2 opens upon receiving an electrical signal from the electric control handle;

[0070] The second pressure opening valve 3 compares the magnitude of the inlet oil pressure and the return oil pressure, and opens when the inlet oil pressure is greater than the return oil pressure.

[0071] The return oil from the rodless chamber of the hydraulic cylinder 11 enters the return oil circuit 14 through the second pressure opening valve 3, causing the back pressure of the return oil from the rodless chamber of the hydraulic cylinder 11 to decrease.

[0072] This embodiment ensures that the second pressure opening valve 3 in the bypass return oil system only opens when the inlet oil pressure is greater than the return oil pressure, thereby reducing the return oil back pressure and allowing the stick, bucket, and other moving parts to unload quickly.

[0073] In one specific embodiment, the step further includes:

[0074] The range of the output signal after controller processing is set to 0-c, where c>1;

[0075] The electro-proportional valve 6 is fully closed when it receives signal 0, fully open when it receives signal c, and opens proportionally when it receives a signal between 0 and c.

[0076] When throttle valve 5 receives a signal from the controller and anticipates that the piston of hydraulic cylinder 11 is about to leave the buffer zone, throttle valve 5 fully opens, and electro-proportional opening valve 6 also fully opens. Oil flows through the valve core of throttle valve 5 into electro-proportional opening valve 6. At this point, the throttle is fully open, and the back pressure generated by the throttle opening cancels out the impact of entering the buffer zone. The return oil is throttled via the buffer zone position electrical signal and the operating handle control signal to limit the pressure surge in hydraulic cylinder 11 when leaving the buffer zone.

[0077] In one specific embodiment, the controller output signal is obtained by processing the position sensor signal and the electric handle opening ratio signal.

[0078] To describe this solution more clearly, a specific embodiment is used as an example below:

[0079] The hydraulic cylinder 11 has buffer zones at both ends to prevent it from impacting the end cap when extended or retracted to its fullest position. However, when the hydraulic cylinder 11 extends, it leaves the rodless chamber buffer zone, and when it retracts, it leaves the rod chamber buffer zone, which also generates an impact. The return oil throttling speed control opens the throttle valve 5 through the combined action of the signal from the first position sensor 9 and the operation signal from the electric control handle. The return oil enters the left side of the electro-proportional opening valve 6 through the valve core opened by the throttle valve 5. The throttle valve core of the electro-proportional opening valve 6 opens, and the return oil generates back pressure due to the opening of the throttle port of the electro-proportional opening valve 6, which cancels out the impact caused by leaving the buffer zone, reducing the impact of the oil leaving the rod chamber buffer zone. When the hydraulic cylinder 11 extends from the top, the second position sensor 10 sends a signal to the throttle valve 5 based on the position of the hydraulic cylinder 11 in the buffer zone. The throttle valve 5 opens under the combined signal of the second position sensor 10 and the operating handle. The return oil enters the left side of the electro-proportional opening valve 6 through the valve core of the throttle valve 5. The throttle valve core of the electro-proportional opening valve 6 opens, and the return oil generates back pressure due to the opening of the throttle port of the electro-proportional opening valve 6, which cancels out the impact caused by leaving the buffer zone, reducing the impact feeling caused by the oil leaving the rod chamber of the buffer zone.

[0080] The smaller the amplitude of the electric control handle, the shorter the stroke, the greater the throttling, and the smaller the flow rate. The proportional opening valve 6 is closed when the signal is less than or equal to 0, and opened proportionally when it is greater than 0. In the rodless chamber buffer zone, the second position sensor 10 provides an electrical signal x1(0, ​​1, a), which is 0 when exiting the buffer zone and a when fully entering it. If the complete range electrical signal of the electric control handle is x2(0, b, c), that is, the electric control handle signal is c when fully open and 0 when no electric control handle operation is performed, then b is defined as follows: when the electric control handle signal is greater than b, the system's movement speed at the current flow rate is slower than the subsequent impact speed of the hydraulic cylinder 11; when the electric control handle signal is less than b, the cylinder's working speed is less than the impact speed when leaving the buffer zone. The electrical signal obtained by the proportional opening valve 2 is set to (1 / x1)*(b-x2). Controlled by the output signal x3 after processing by the controller, the signal before processing includes the position sensor signal x1 and the handle opening ratio signal x2. The range of the processed signal x3 is 0-c (c>1). When the calculated value of (1 / x1)*(b-x2) is less than or equal to 0, the controller output value is 0. When the calculated value of (1 / x1)*(b-x2) is greater than or equal to c, the controller output value is c. The electro-proportional opening valve 6 is fully closed when it receives signal 0, fully open when it receives signal c, and opens proportionally when it receives intermediate signals.

[0081] Operating Condition 1: When the electric control handle signal x2 is less than b, the hydraulic cylinder 11 is about to leave the buffer zone, the position sensor signal is less than 1, the signal of the electro-proportional opening valve 6 quickly reaches the maximum electrical signal, the electro-proportional opening valve 6 is fully opened, the throttle valve 5 is then fully opened, and the return oil throttle control is activated.

[0082] Condition 2: When the electric control handle signal x2 is less than b, the hydraulic cylinder 11 leaves the position sensor from the buffer zone and the signal becomes 0. The signal of the electro-proportional opening valve 6 is 0. The throttle valve 5 is almost fully opened and then closes after a delay. The return oil flow rate is restored to the maximum flow rate.

[0083] Operating Condition 3: When the electric control handle signal x2 is greater than b, the hydraulic cylinder 11 is about to leave the buffer zone, the position sensor signal is less than 0, the electro-proportional opening valve 6 signal is less than 0, and the throttle valve 5 does not open. Return throttle valve 5 control is applied. That is, when the electric control handle is opened to a higher working speed, the return throttle speed control is not activated.

[0084] Condition 4: The electric control handle signal x2 is greater than b, the hydraulic cylinder 11 leaves the buffer zone position sensor signal is less than 0, the electro-proportional opening valve 6 signal is less than 0, the throttle valve 5 does not open, and the return oil throttle valve 5 is controlled.

[0085] In this embodiment, the throttle valve 5 can be a two-position two-way throttle valve 5.

[0086] Furthermore, the present invention also provides a working machine, which includes, but is not limited to, an excavator, and may also be a bucket truck, etc., specifically including:

[0087] The hydraulic cylinder 11, electric control handle, main directional valve 4, and oil tank 8 are provided. The rod chamber of the hydraulic cylinder 11 is connected to the oil tank 8 through the first main oil circuit 15, and the rodless chamber of the hydraulic cylinder 11 is connected to the oil tank 8 through the second main oil circuit 16. The first main oil circuit 15 and the second main oil circuit 16 both pass through the main directional valve 4. The electric control handle is used to send a signal to the main directional valve 4 to extend or retract the hydraulic cylinder 11. The hydraulic control system of the above-mentioned working machinery is located between the first main oil circuit 15 and the second main oil circuit 16.

[0088] In this embodiment, the first pressure opening valve 1 determines whether there is pressure on the return oil circuit 14, and the bypass return oil system is not opened when the oil circuit is sucked in; the electromagnetic opening valve 2 determines whether the electric control handle is in the rod chamber oil inlet operation, and is only opened when the electric control handle is in the rod chamber oil inlet operation.

[0089] When both the first pressure opening valve 1 and the solenoid opening valve 2 are open, the magnitudes of the return oil pressure and the inlet oil pressure are determined. When the second pressure opening valve 3 is opened by the pressure of the rod chamber of the hydraulic cylinder 11, most of the return oil from the rodless chamber enters the return oil circuit 14 through the second pressure opening valve 3, thus reducing back pressure during return oil flow. To address the impact caused by sudden changes in flow rate when the hydraulic cylinder 11 enters and exits the buffer zone, a throttle valve 5 and an electro-proportional control valve are added to the return oil circuit 14 to control the return oil back pressure and reduce the impact caused by the hydraulic cylinder 11 leaving the buffer zone.

[0090] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A hydraulic control system for a work machinery, wherein, The working machinery includes a hydraulic cylinder (11), an electric control handle, a main directional valve (4), and an oil tank (8). The rod chamber of the hydraulic cylinder (11) is connected to the oil tank (8) through a first main oil circuit (15), and the rodless chamber of the hydraulic cylinder (11) is connected to the oil tank (8) through a second main oil circuit (16). The first main oil circuit (15) and the second main oil circuit (16) both pass through the main directional valve (4). The electric control handle is used to send a signal to the main directional valve (4) indicating that the hydraulic cylinder (11) is extended or retracted. The hydraulic control system includes a bypass return oil system, which includes: The first bypass circuit (12) has a first end connected to the first main oil circuit (15) near the hydraulic cylinder (11), and a second end connected to the second main oil circuit (16) near the main directional valve (4). The first bypass circuit (12) is provided with a first pressure opening valve (1) and a solenoid opening valve (2) in sequence from the first end to the second end. The solenoid opening valve (2) is connected to the working port away from the first pressure opening valve (1) and the left side of the second pressure opening valve (3). The right side of the second pressure opening valve (3) is connected to the second main oil circuit (16) near the main directional valve (4). The solenoid opening valve (2) is electrically connected to the electric control handle. The second bypass circuit (13) is connected at one end to the second main oil circuit (16) near the hydraulic cylinder (11), and at the other end to the left side of the first pressure opening valve (1); The return oil line (14) is connected at one end to the second main oil line (16) and at the other end to the oil tank (8) via the second pressure opening valve (3).

2. The hydraulic control system for the operating machinery according to claim 1, characterized in that, The second pressure opening valve (3) is provided with an oil discharge hole that meets the maximum flow rate of the rodless chamber return oil of the hydraulic cylinder (11).

3. The hydraulic control system for the operating machinery according to claim 1, characterized in that, The first pressure opening valve (1), the electromagnetic opening valve (2) and the second pressure opening valve (3) are all provided with a valve port and a valve core that is movable in the valve port by a spring.

4. The hydraulic control system for the operating machinery according to claim 1, characterized in that, The opening pressure of the first pressure opening valve (1) is not less than 0.5 MPa.

5. The hydraulic control system for the operating machinery according to any one of claims 1 to 4, characterized in that, Also includes: The return oil throttling system includes an electro-proportional opening valve (6) and a throttle valve (5). The electro-proportional opening valve (6) is located on the return oil passage (14) between the oil tank (8) and the second pressure opening valve (3). The throttle valve (5) is located on the second main oil passage (16) between the main directional valve (4) and the electro-proportional opening valve (6). The second main oil passage (16) is connected to the inlet of the electro-proportional opening valve (6) and the throttle valve (5). The outlet of the throttle valve (5) is connected to the left side of the electro-proportional opening valve (6). A first position sensor (9) and a second position sensor (10), wherein the first position sensor (9) is located in the buffer zone of the rod chamber of the hydraulic cylinder (11), and the second position sensor (10) is located in the buffer zone of the rodless chamber of the hydraulic cylinder (11); The controller is electrically connected to the first position sensor (9) and the second position sensor (10), and electrically connected to the throttle valve (5) and the electro-proportional opening valve (6). The controller is used to control the throttle valve (5) and the electro-proportional opening valve (6) to open for throttling based on the signal detected by the first position sensor (9) or the second position sensor (10).

6. The hydraulic control system for the operating machinery according to claim 5, characterized in that, It also includes a return oil branch, one end of which is connected to the left side of the electro-proportional opening valve (6), and the other end is connected to the return oil line (14) between the electro-proportional opening valve (6) and the oil tank (8). A pressure delay valve (7) is provided on the return oil branch.

7. A hydraulic control method for a work machinery, applied to the hydraulic control system of the work machinery according to any one of claims 1 to 6, characterized in that, Including the following steps: In response to the oil inlet operation of the rod chamber of the hydraulic cylinder (11), the first pressure opening valve (1) opens under pressure; The electromagnetic opening valve (2) opens upon receiving an electrical signal from the electric control handle; The second pressure opening valve (3) compares the magnitude of the inlet oil pressure and the return oil pressure, and opens when the inlet oil pressure is greater than the return oil pressure; The return oil from the rodless chamber of the hydraulic cylinder (11) enters the return oil circuit (14) through the second pressure opening valve (3), causing the back pressure of the return oil from the rodless chamber of the hydraulic cylinder (11) to decrease.

8. The hydraulic control method for operating machinery according to claim 7, characterized in that, It also includes the following steps: The range of the output signal after controller processing is set to 0-c, where c>1; The electro-proportional valve (6) is fully closed when it receives signal 0, fully open when it receives signal c, and opens proportionally when it receives a signal between 0 and c. When the throttle valve (5) receives a signal from the controller and anticipates that the piston of the hydraulic cylinder (11) is about to leave the buffer zone, the throttle valve (5) and the electro-proportional opening valve (6) are fully opened. The oil enters the left side of the electro-proportional opening valve (6) through the throttle valve (5), and the throttle port of the electro-proportional opening valve (6) is opened, and the back pressure formed cancels out the impact of entering the buffer zone.

9. The hydraulic control method for operating machinery according to claim 8, characterized in that, The controller output signal is obtained by processing the position sensor signal and the electric control handle opening ratio signal.

10. A type of operating machinery, characterized in that, include: The hydraulic control system for the operating machinery as described in any one of claims 1 to 6.

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