A control circuit and method for realizing differential switching synchronization of a hydraulic oil circuit

Abstract

This invention discloses a control method for differential switching synchronization of hydraulic circuits, comprising the following steps: A basic power source injects hydraulic oil into an accumulator for pre-storage. Hydraulic oil supplied by the pump is injected into the rodless chamber through the injection directional valve, while hydraulic oil in the rod chamber is simultaneously injected into the rodless chamber, causing the piston of the injection cylinder to slowly extend differentially. The injection quick-inlet pilot valve is opened, and by adjusting the pilot damping, the pilot pressure of the injection quick-inlet valve and the injection quick-out valve is simultaneously relieved, allowing the main valves of both to open smoothly and synchronously. This allows hydraulic oil from the accumulator to be rapidly injected into the rodless chamber, while simultaneously draining the oil into the tank, causing the piston of the injection cylinder to extend rapidly. The injection quick-inlet valve and the injection quick-out valve are closed, and the basic power source injects hydraulic oil into the rod chamber through the injection directional valve while the hydraulic oil in the rodless chamber is drained, causing the piston of the injection cylinder to retract. This invention ingeniously achieves a smooth transition from differential extension to rapid extension in the injection circuit.

Description

Technical Field

[0001] This invention relates to the field of die-casting machine technology, and more specifically to the application of hydraulic systems for switching between fast and slow motion of the drive cylinder of a die-casting cylinder. Background Technology

[0002] High-pressure die casting (or simply die casting) is essentially a method of obtaining a casting by filling a die-casting mold cavity with liquid or semi-liquid metal at a high speed under high pressure, and then shaping and solidifying it under pressure. In practical applications, different injection speeds and forces are often required for different working conditions. This is usually achieved by controlling the sliding motion with hydraulic oil to change the injection speed, thus requiring a hydraulic circuit to control the injection module.

[0003] The injection circuit is generally divided into open-loop control circuit and closed-loop control circuit. The injection process generally has three stages: slow, fast and pressurization. In the slow stage, the oil comes from the oil pump, and in the fast and pressurization stages, the oil comes from the accumulator. The fast stage can be divided into multiple stages such as the first fast and the second fast.

[0004] The selection of the system oil pump is mainly based on the mold opening and closing action, which will lead to a certain limitation on the speed at the injection end. Under normal circumstances, the system oil pump can provide enough power to keep the slow speed in the injection stage within the range of 0.2 to 0.3 m / s. However, this speed range is insufficient to cover the product process requirements for the slow speed range. The most intuitive way to solve this problem is to increase the pump displacement, but this will lead to energy waste and increased costs. Alternatively, a fast circuit can be added to use the energy of the accumulator for speed increase, but this will also have some energy loss and increased costs. Another option is to achieve speed control through a hydraulic cylinder structure, but this solution has a complex structure, high processing and manufacturing costs, and inconvenient adjustment of the speed switching position, making it impractical and not cost-effective.

[0005] Currently, most existing technologies use proportional valves for oil circuit control to achieve differential control in the slow stage. Although the control accuracy is high, proportional valves are expensive. At the same time, in the fast stage, there is an uncontrollable time difference between the electrical control of the pilot control valve and the response of the oil valve, which can easily cause the instantaneous speed and pressure to be uncontrollable during the transition between the slow and fast stages. Summary of the Invention

[0006] This invention addresses the shortcomings of differential control in existing technologies by providing a hydraulic circuit differential switching synchronous control loop and method. In the slow-speed phase, the power required for injection is not very high. By recovering and utilizing the energy of the injection section, the system power remains unchanged, which can satisfy both the thrust output and the injection distance requirements in the slow-speed phase. At the same time, it simplifies the hydraulic circuit, saves costs, and improves the stability of injection pressure control.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A control circuit for achieving differential switching synchronization of hydraulic circuits includes a basic power source, an injection directional valve, an injection cylinder, an accumulator, an injection quick inlet valve, and an injection quick outlet valve. The injection cylinder includes a rod chamber and a rodless chamber, which are respectively connected to the injection directional valve pipeline. The rod chamber is also connected to the injection quick outlet valve pipeline. The basic power source is connected to the injection quick inlet valve and the injection directional valve pipeline. The injection quick inlet valve is also connected to the injection quick outlet valve and the rodless chamber. The rod chamber is also connected to the connecting pipeline of the injection quick outlet valve and the rodless chamber. The basic power source is connected to the injection quick inlet valve through the accumulator. By energizing and reversing the injection quick inlet valve, the pilot pressure of the injection quick inlet valve and the injection quick outlet valve can be relieved, thereby simultaneously opening the main valves of both valves.

[0009] Preferably, the injection quick inlet valve includes a first switching main valve, a first pilot damper, and a pilot directional valve connected together, and the injection quick outlet valve includes a second switching main valve and a second pilot damper connected together. The pilot directional valve is also connected to the second pilot damper. By energizing and switching the pilot directional valve, the pilot pressure of the injection quick inlet valve and the injection quick outlet valve can be relieved, thereby simultaneously opening the first switching main valve and the second switching main valve.

[0010] Preferably, the pilot directional valve is connected to the first oil tank.

[0011] Preferably, the injection quick discharge valve and the rodless chamber are provided with branch pipes for connecting to the rod chamber, and the branch pipes are provided with differential check valves that allow hydraulic oil to flow from the rod chamber to the rodless chamber.

[0012] Preferably, an energy storage directional valve is also connected between the basic power source and the energy accumulator, which controls the on / off connection between the hydraulic oil supply source and the energy accumulator via electromagnetic control.

[0013] Preferably, the injection quick discharge valve is connected to a second oil tank.

[0014] Preferably, the injection reversing valve is connected to a third oil tank.

[0015] A control method for differential switching synchronization of hydraulic circuits includes the following steps:

[0016] S1. Hydraulic oil is injected into the accumulator from the basic power source to pre-store the hydraulic oil.

[0017] S2. The basic power source injects hydraulic oil into the rodless chamber through the injection reversing valve, and the hydraulic oil in the rod chamber is injected into the rodless chamber so that the piston of the injection cylinder extends slowly and differentially.

[0018] S3. By energizing and switching the pilot directional valve, the pilot pressure of the injection quick inlet valve and the injection quick outlet valve is relieved, and then the main valves of both are opened simultaneously. The accumulator injects hydraulic oil into the rodless chamber through the injection quick inlet valve. The hydraulic oil in the rod chamber is simultaneously injected into the rodless chamber and discharged through the injection quick outlet valve, so that the differential extension of the piston of the injection cylinder is switched to synchronous rapid extension.

[0019] S4. After the piston is fully extended, close the injection quick oil inlet valve and the injection quick oil outlet valve. The base power source injects hydraulic oil into the rod chamber through the injection reversing valve, while the hydraulic oil in the rodless chamber is discharged to retract the piston of the injection cylinder.

[0020] Therefore, the present invention has the following beneficial effects:

[0021] (1) The present invention uses the structure of the control circuit for differential switching synchronization of hydraulic oil circuit. By setting a pilot directional valve, it realizes the simultaneous control of the connected fast oil inlet main valve and the fast oil discharge main valve of injection, so as to achieve the simultaneous oil inlet of the rodless chamber of the injection cylinder and the oil discharge of the rod chamber through the fast oil discharge valve of injection, thereby realizing rapid extension.

[0022] (2) The present invention controls the valve cores of the fast oil inlet main valve and the injection fast oil discharge main valve to be completely synchronized by setting the first pilot damper and the second pilot damper, and the time required to achieve the synchronization state is precisely controllable.

[0023] (3) By setting a differential check valve between the rodless chamber and the rod chamber of the injection cylinder, the energy of the injection section is recovered and utilized. Under the premise of unchanged system power, the power output of the oil pump is reduced, which can not only meet the output of thrust, but also improve the peak speed of the slow injection stage, thereby expanding the adjustment range of the slow injection speed.

[0024] (4) This invention not only realizes the switching from differential to synchronous hydraulic circuit, but also realizes the damping controllability from the differential extension stage to the rapid extension stage of injection, so as to achieve a smooth transition from slow to fast speed and avoid speed jitter caused by uncontrollable extension rod acceleration. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is the overall oil circuit diagram of the injection system of the present invention;

[0027] Figure 2 This is a flowchart of a control method for differential switching synchronization of hydraulic circuits according to the present invention.

[0028] The codes in the diagram are as follows: 1-Basic power source, 2-Injection directional valve, 3-Injection cylinder, 3.1-Rod chamber, 3.2-Rodless chamber, 4-Accumulator, 5-Injection quick inlet valve, 5.1-First switching main valve, 5.2-First pilot damper, 5.3-Pilot directional valve, 6-Differential check valve, 7-Injection quick discharge valve, 7.1-Second switching main valve, 7.2-Second pilot damper, 8.1-First oil tank, 8.2-Second oil tank, 8.3-Third oil tank, 9-Storage directional valve. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments and accompanying drawings. These embodiments are provided to enable those skilled in the art to better understand the invention and do not constitute any limitation on the invention.

[0030] Example 1:

[0031] Hydraulic oil is an incompressible liquid; therefore, it cannot store pressure energy. Other media must be used to convert and store pressure energy. For example, a bladder-type accumulator, which utilizes the compressibility of gas (nitrogen), is a device for storing hydraulic oil. The bladder-type accumulator consists of an oil section and a gas section with a gas seal. The oil around the bladder is connected to the oil circuit. When the pressure increases, oil enters the accumulator, and the gas is compressed until the system pipeline pressure no longer rises. When the pipeline pressure decreases, the compressed air expands, pushing the oil back into the circuit, thus slowing the pressure drop.

[0032] Accumulator: A container that converts the hydraulic energy of pressurized fluid into potential energy for storage, and then converts the potential energy back into hydraulic energy to perform work when the system needs it. Therefore, accumulators can serve as auxiliary or emergency power sources, replenishing system leaks, stabilizing system operating pressure, and absorbing pump pulsations and hydraulic shocks in the circuit. Based on these characteristics, accumulators are used as auxiliary oil sources in hydraulic systems to provide users with suitable hydraulic pressure.

[0033] Directional control valve: It changes the direction of oil flow or connects and closes oil circuits by using the relative movement between the valve core and the valve body, thereby changing the working state of the hydraulic system.

[0034] Please see Figure 1 A control circuit for differential switching synchronization of hydraulic oil circuits includes a basic power source 1, an injection directional valve 2, an injection cylinder 3, an accumulator 4, an injection rapid inlet valve 5, and an injection rapid outlet valve 7. The injection cylinder 3 includes a rod chamber 3.1 and a rodless chamber 3.2. The rod chamber 3.1 and the rodless chamber 3.2 are respectively connected to the injection directional valve 2 pipeline. The rod chamber 3.1 is also connected to the injection rapid outlet valve 7 pipeline. The basic power source 1 is connected to the injection rapid inlet valve 5 and the injection directional valve 2 pipeline. The injection rapid inlet valve 5 is also connected to the injection rapid outlet valve 7 and the rodless chamber 3.2. The rod chamber 3.1 is also connected to the injection rapid outlet valve 7 and the rodless chamber 3.2 via a connecting pipeline. The basic power source 1 is connected to the injection rapid inlet valve 5 through the accumulator 4.

[0035] The oil circuit described above comprises the following stages during operation:

[0036] 1. Energy storage stage: When the energy storage reversing valve 9 is energized, the injection quick oil inlet valve 5 and the injection quick oil outlet valve 7 are closed. The hydraulic system is connected from point 1, and the basic power source 1 enters the accumulator 4 through the first energy storage valve 9 for energy storage. After reaching the set value, the relevant energy storage action is automatically stopped.

[0037] 2. Differential control piston extension to achieve slow injection stage: At this time, the oil circuit is in a closed loop state. The basic power source 1 continuously provides pressurized oil to the injection system. At this time, the injection reversing valve 2 is energized and the electric valve core is in the left position. The basic power source 1 provides pressurized oil to the rodless chamber 3.2 in the injection cylinder 3 through the injection reversing valve 2. At the same time, the oil in the rod chamber is squeezed by pressure and enters the rodless chamber 3.2 through the differential check valve 6, causing the piston rod of the injection cylinder 3 to perform a slow extension action.

[0038] It should be noted that the slow speed achieved in this stage is only through the oil inlet control of the rodless chamber 3.2, which is a one-way differential control method. In this stage, the setting of the differential check valve 6 allows the oil in the rodless chamber to enter the rod chamber under pressure, which also increases the peak speed of the slow injection stage and expands the adjustment range of the slow injection speed.

[0039] 3. Synchronous control of piston extension to achieve rapid injection stage: After the piston is slowly ejected in the previous stage to reach the set position, the electric valve core of the injection reversing valve 2 is in the neutral position. While maintaining consistency with the slow injection stage, when the pilot reversing valve 5.3 is energized, the pilot oil of the first switch main valve 5.1 and the second switch main valve 7.1 is discharged to the first oil tank 8.1 and the second oil tank 8.2 respectively through the first pilot damper 5.2 and the second pilot damper 7.2 to relieve the pressure of the pilot part accumulated in step S2. At the same time, the valve cores of the first switch main valve 5.1 and the second switch main valve 7.1 open.

[0040] It should be noted that the first pilot damper 5.2 and the second pilot damper 7.2 can be set as needed to adjust the flow rate of pilot oil draining into the first oil tank 8.1 and the second oil tank 8.2, thereby adjusting the opening speed of the valve cores of the first main valve 5.1 and the second main valve 7.1, so that the two valve cores open simultaneously under the same time delay.

[0041] After the valve cores of the first main valve 5.1 and the second main valve 7.1 are opened, the accumulator 4 injects hydraulic oil into the rodless chamber 3.2 through the first main valve 5.1, while the hydraulic oil in the rod chamber 3.1 is discharged to the second oil tank 8.2 through the injection quick discharge valve 7, so that the piston of the injection cylinder can extend quickly.

[0042] It should be noted that during this stage, the piston's rapid extension is achieved by synchronously controlling the oil output from the rod chamber 3.1 and the oil inlet from the rodless chamber 3.2.

[0043] Specifically, the rapid injection inlet valve 5 includes a first main valve 5.1, a first pilot damper 5.2, and a pilot directional valve 5.3 connected to each other. The rapid injection outlet valve 7 includes a second main valve 7.1 and a second pilot damper 7.2 connected to each other. The pilot directional valve 5.3 is also connected to the second pilot damper 7.2. By energizing the pilot directional valve 5.3, the pilot pressure of the rapid injection inlet valve 5 and the rapid injection outlet valve 7 can be relieved, thereby simultaneously opening the first main valve 5.1 and the second main valve 7.1.

[0044] The first pilot damper 5.2 is connected to the first oil tank. Branch lines for connecting to the rod chamber are provided on the connecting pipelines of the injection quick discharge valve 7 and the rodless chamber 3.2. Differential check valves 6 are installed in these branch lines to allow hydraulic oil to flow from the rod chamber 3.1 to the rodless chamber 3.2. An energy storage directional valve 9, which electromagnetically controls the connection and disconnection between the hydraulic oil supply source and the accumulator 4, is also connected between the basic power source 1 and the accumulator 4. The injection directional valve 2 and the injection quick discharge valve 7 are respectively connected to the second and third oil tanks required for circuit oil drainage.

[0045] IV. Piston Rod Retraction Stage: At this time, the differential check valve 6 remains closed, the injection quick pilot valve 5.3 is de-energized, the first switch main valve 5.1 of the injection quick oil inlet valve and the second switch main valve 7.1 of the injection quick oil outlet valve are closed, the right side of the injection directional valve 2 is energized, but the valve core is in the right position. The pressure oil from the basic power source 1 enters the rod chamber of the injection cylinder 3 through the directional valve 2, causing the oil in the rodless chamber 3.2 to flow to the third oil tank 8.3. The piston rod of the injection cylinder retracts.

[0046] Example 2:

[0047] In the synchronous control method of the pilot directional valve 5.3 described in Embodiment 1, a pilot directional valve can also be installed on the second switching main valve 7.1. By starting the pilot directional valve 5.3 and the newly installed pilot directional valve, and by adjusting the first pilot damper 5.2 and the second pilot damper 7.2, the opening speed of the valve cores of the first opening main valve 5.1 and the second switching main valve 7.1 can be controlled, thereby controlling the valve cores of the first switching main valve and the second switching main valve to open completely synchronously.

[0048] It should be noted that the control circuit for differential switching synchronization of hydraulic oil circuits provided in this embodiment has other connection methods similar to those in Embodiment 1, and will not be described in detail here.

[0049] Example 3:

[0050] A control method for achieving differential switching synchronization in hydraulic circuits includes four steps, corresponding to four different working stages, as detailed below:

[0051] S1. Hydraulic oil is injected into the accumulator 4 from the basic power source 1 to pre-store the hydraulic oil.

[0052] Energy storage stage: When the energy storage reversing valve 9 is energized, the injection quick oil inlet valve 5 and the injection quick oil outlet valve 7 are closed. The hydraulic system is connected from point 1, and the basic power source enters the accumulator 4 through the first energy storage valve 9 for energy storage. After reaching the set value, the relevant energy storage action is automatically stopped.

[0053] S2. The basic power source 1 injects hydraulic oil into the rodless chamber through the injection reversing valve 2, and the hydraulic oil in the rod chamber 3.1 is injected into the rodless chamber 3.2, so that the piston of the injection cylinder extends slowly and differentially.

[0054] Differential control piston extension to achieve slow injection stage: At this time, the oil circuit is in closed loop state, the basic power source 1 continuously provides pressurized oil to the injection system, the injection reversing valve 2 is energized and the electric valve core is in the left position, the basic power source 1 provides pressurized oil to the rodless chamber 3.2 in the injection cylinder 3 through the injection reversing valve 2, and at the same time, the oil in the rod chamber is squeezed by pressure and enters the rodless chamber 3.2 through the differential check valve 6, causing the piston rod of the injection cylinder 3 to perform a slow extension action.

[0055] It should be noted that in this stage, the slow speed is achieved only by controlling the oil inlet of the rodless chamber 3.2. It is a one-way, differential control method. In this stage, the setting of the differential check valve 6 allows the oil in the rodless chamber to enter the rod chamber under pressure, which also increases the peak speed of the slow injection stage and expands the adjustment range of the slow injection speed.

[0056] S3. By energizing the pilot directional valve 5.3, the pilot pressure of the injection quick inlet valve 5 and the injection quick outlet valve 7 is relieved, and then the main valves of both are opened simultaneously. The accumulator 4 injects hydraulic oil into the rodless chamber 3.2 through the injection quick inlet valve 5. The hydraulic oil in the rod chamber 3.1 is simultaneously injected into the rodless chamber and discharged through the injection quick outlet valve 7, so that the differential extension of the piston of the injection cylinder is switched to synchronous rapid extension.

[0057] Synchronous control of piston extension to achieve rapid injection stage: After the piston is slowly ejected in the previous stage to reach the set position, the electric valve core of the injection reversing valve 2 is in the neutral position. While maintaining consistency with the slow injection stage, at the instant the pilot reversing valve 5.3 is energized, the pilot oil of the first switching main valve 5.1 and the second switching main valve 7.1 is discharged to the first oil tank 8.1 and the second oil tank 8.2 respectively through the first pilot damper 5.2 and the second pilot damper 7.2 to relieve the pressure of the pilot part accumulated in step S2. At the same time, the valve cores of the first switching main valve 5.1 and the second switching main valve 7.1 open.

[0058] It should be noted that the first pilot damper 5.2 and the second pilot damper 7.2 can be set as needed to adjust the flow rate of pilot oil draining into the first oil tank 8.1 and the second oil tank 8.2, thereby adjusting the opening speed of the valve cores of the first main valve 5.1 and the second main valve 7.1, so that the two valve cores open simultaneously under the same time delay.

[0059] After the valve cores of the first main valve 5.1 and the second main valve 7.1 are opened, the accumulator 4 injects hydraulic oil into the rodless chamber 3.2 through the first main valve 5.1, while the hydraulic oil in the rod chamber 3.1 is discharged to the second oil tank 8.2 through the injection quick discharge valve 7, so that the piston of the injection cylinder can extend quickly.

[0060] It should be noted that during this stage, the piston's rapid extension is achieved by synchronously controlling the oil output from the rod chamber 3.1 and the oil inlet from the rodless chamber 3.2.

[0061] Specifically, through steps S3-S4, the piston extension is completed from slow to fast speed. This achieves both the flow rate change of the oil entering the rodless chamber 3.2 of the injection cylinder from the accumulator 4 and the controllable flow rate change of the oil returning to the oil tank from the rod chamber 3.1 of the injection cylinder. Finally, it achieves a smooth transition from differential piston rod extension to rapid extension.

[0062] This stage, through the adjustment of the magnitude of the first and second pilot dampers, also achieves a smooth transition from the slow injection stage to the fast injection stage, avoiding the vibration problem caused by the uncontrollable acceleration of the piston extension rod.

[0063] S4. After the piston is fully extended, close the injection quick oil inlet valve 5 and the injection quick oil outlet valve 7. The basic power source 1 injects hydraulic oil into the rod chamber through the injection reversing valve 2, while the hydraulic oil in the rodless chamber is discharged to make the piston of the injection cylinder retract.

[0064] During the piston rod retraction phase: The differential check valve 6 remains closed, the injection quick pilot valve 5.3 is de-energized, the first switch main valve 5.1 of the injection quick inlet valve and the second switch main valve 7.1 of the injection quick outlet valve are closed, and the right side of the injection directional valve 2 is energized, but the valve core is in the right position. The pressure oil from the basic power source 1 enters the rod chamber of the injection cylinder 3 through the directional valve 2, causing the oil in the rodless chamber 3.2 to flow to the third oil tank 8.3. The piston rod of the injection cylinder then retracts.

[0065] In this invention, the valve bodies described above are all electrically controlled valves or logic valves. During use, the valve bodies can be opened, closed, switched, or reversed by the control system in combination with the hydraulic system's own pressure.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A control circuit for implementing differential switching synchronization of hydraulic oil paths, characterized by, The application relates to a hydraulic pressure injection system, which comprises a basic power source, a pressure injection reversing valve, a pressure injection cylinder, an accumulator, a pressure injection quick oil inlet valve and a pressure injection quick oil outlet valve. The pressure injection cylinder comprises a rod cavity and a rodless cavity, the rod cavity and the rodless cavity are respectively connected with a pressure injection reversing valve pipeline, the rod cavity is further connected with a pressure injection quick oil outlet valve pipeline, the basic power source is respectively connected with a pressure injection quick oil inlet valve and a pressure injection reversing valve pipeline, the pressure injection quick oil inlet valve is further respectively connected with a pressure injection quick oil outlet valve and a rodless cavity, the rod cavity is further connected with a pressure injection quick oil outlet valve and a rodless cavity pipeline, the basic power source is connected with the pressure injection quick oil inlet valve through the accumulator, and the pressure injection quick oil inlet valve and the pressure injection quick oil outlet valve can be simultaneously opened through electrically-controlled reversing of the pressure injection quick oil inlet valve and the pressure injection quick oil outlet valve. The pressure injection quick oil inlet valve comprises a first switch main valve, a first pilot damping and a pilot reversing valve, the pressure injection quick oil outlet valve comprises a second switch main valve and a second pilot damping, the pilot reversing valve is further connected with the second pilot damping, and the pressure injection quick oil inlet valve and the pressure injection quick oil outlet valve can be simultaneously opened through electrically-controlled reversing of the pilot reversing valve. The pilot reversing valve is connected with a first oil tank.

2. The control circuit for realizing differential switching synchronization of hydraulic oil paths according to claim 1, characterized in that, Branch pipelines for connecting with the rod cavity are arranged on the pressure injection quick oil outlet valve and the rodless cavity pipeline, and differential check valves for allowing hydraulic oil to flow from the rod cavity to the rodless cavity are arranged in the branch pipelines.

3. The control circuit for realizing differential switching synchronization of hydraulic oil paths according to claim 1, characterized in that, An energy storage reversing valve for controlling the on-off of a hydraulic oil supply source and the accumulator through electricity is further arranged between the basic power source and the accumulator.

4. The control circuit for implementing differential switching synchronization of hydraulic oil paths according to claim 1, characterized in that, The pressure injection quick oil outlet valve is connected with a second oil tank.

5. A control method for realizing differential switching synchronization of hydraulic oil paths, based on the control circuit for realizing differential switching synchronization of hydraulic oil paths according to any one of claims 1 to 4, characterized by The pressure injection reversing valve is connected with a third oil tank. The application further discloses a hydraulic pressure injection method. S1, the basic power source injects hydraulic oil into the accumulator to pre-store the hydraulic oil; S2, the basic power source injects hydraulic oil into the rodless cavity through the pressure injection reversing valve, and the hydraulic oil in the rod cavity is injected into the rodless cavity to make the piston of the pressure injection cylinder differentially and slowly extend; S3, the pilot part pressure of the pressure injection quick oil inlet valve and the pressure injection quick oil outlet valve is removed through electrically-controlled reversing of the pilot reversing valve, and the main valves of the two valves are simultaneously opened, the accumulator injects hydraulic oil into the rodless cavity through the pressure injection quick oil inlet valve, the hydraulic oil in the rod cavity is simultaneously injected into the rodless cavity and discharged through the pressure injection quick oil outlet valve, so that the piston of the pressure injection cylinder is differentially extended and switched to synchronous and rapid extension; S4, after the piston is rapidly extended to completely extend, the pressure injection quick oil inlet valve and the pressure injection quick oil outlet valve are closed, the basic power source injects hydraulic oil into the rod cavity through the pressure injection reversing valve, and the hydraulic oil in the rodless cavity is discharged, so that the piston of the pressure injection cylinder is retracted.

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