A hydraulic control system and control method for a tube expander

Abstract

This invention provides a hydraulic control system and method for a workpiece expansion machine, relating to the field of hydraulic control technology. The system includes an oil supply device, a control valve group, and an actuator. The control valve group includes an oil circuit board, a main pressure reducing valve, a first two-position four-way solenoid valve, a first three-position four-way solenoid valve, a second two-position four-way solenoid valve, a second three-position four-way solenoid valve, a third three-position four-way solenoid valve, a first damping two-way valve, a second damping two-way valve, a third damping two-way valve, a fourth damping two-way valve, and a fourth three-position four-way solenoid valve. The actuator includes a first back pressure cylinder, a second back pressure cylinder, a third back pressure cylinder, a fourth back pressure cylinder, and a workpiece expansion cylinder. During operation, the system sequentially performs the following actions: pressure building by the oil supply device, providing back pressure to the workpiece, slow downward movement of the workpiece expansion cylinder, rapid workpiece expansion, rapid return of the workpiece expansion cylinder, slow return of the workpiece expansion cylinder, pressure relief of the back pressure cylinder, and reset of the back pressure cylinder. This system can absorb the impact force during the operation of the workpiece expansion machine, ensuring safe and reliable operation and reducing the scrap rate.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, and in particular to a hydraulic control system and control method for a fracture expansion machine. Background Technology

[0002] Traditional engine connecting rods are mostly machined in parts, which introduces precision errors during actual production, affecting the connecting rod's service life. Subsequently, methods such as milling and cutting were used to separate the connecting rod after it was machined as a whole. While this improved the connecting rod's precision, it reduced production efficiency due to the increased number of steps. In recent years, hydraulic fracture technology has been adopted for connecting rod machining. The hydraulic fracture machine is a new type of equipment that separates the connecting rod body and bearing cap after the engine connecting rod has been machined as a whole. The connecting rod body and bearing cap mating surfaces obtained by the hydraulic fracture machine can fully engage without additional machining, and it has a large contact area and high load-bearing strength, greatly improving production efficiency.

[0003] However, in actual production, due to the immaturity of the hydraulic system controlling the expansion machine, the expansion machine has a large impact force when it is working, which not only affects the service life of the expansion machine, but also results in a high product scrap rate, which increases production costs. The low product yield also indirectly affects production efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulic control system and control method for a fracture breaker, which can absorb the impact force during the operation of the fracture breaker, ensure the safety and reliability of the fracture breaker operation, reduce the scrap rate, increase the service life of the fracture breaker and the product yield, reduce production costs, and improve production efficiency.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A hydraulic control system for a fracture expansion machine includes an oil supply device, a control valve group, and an actuator. The oil supply device supplies oil to the actuator through the control valve group, thereby controlling the actuator to perform extension and retraction movements.

[0007] The oil supply device includes an oil tank and an oil pump unit. The oil supply device is equipped with an output port GP, an oil return port GT, and an oil drain port GL. The oil return port GT and the oil drain port GL are both connected to the oil tank. The output port GP is connected to an oil supply accumulator. The oil inlet of the oil pump unit is connected to the oil tank, and the oil outlet is connected to the output port GP.

[0008] The control valve assembly includes an oil circuit board with oil ports KP, KT, KL, AD, BC, BD, CD, DC, DD, EC, and ED. Oil port KP is connected to the output port GP of the oil supply device, oil port KT is connected to the return port GT of the oil supply device, oil port KL is connected to the drain port GL of the oil supply device, and oil ports AD, BC, BD, CD, DC, DD, EC, and ED are connected to the actuator.

[0009] The control valve group also includes a main pressure reducing valve, a first two-position four-way solenoid valve, a first three-position four-way solenoid valve, a second two-position four-way solenoid valve, a second three-position four-way solenoid valve, a third three-position four-way solenoid valve, a first damping two-way valve, a second damping two-way valve, a third damping two-way valve, a fourth damping two-way valve, and a fourth three-position four-way solenoid valve.

[0010] The main pressure reducing valve includes oil ports JA, JB and JC. Oil port JA is connected to oil port KP on the oil circuit board, and oil port JC is connected to oil port KL on the oil circuit board.

[0011] The first two-position four-way solenoid valve includes oil ports AA, AB, AP and AT. Oil port AA is blocked, oil port AB is connected to oil port AD of the oil circuit board, oil port AP is connected to oil port JB of the main pressure reducing valve, and oil port AT is connected to oil port KT of the oil circuit board.

[0012] The first three-position four-way solenoid valve includes oil ports BA, BB, BP and BT. Oil port BA is connected to oil port BC of the oil circuit board, oil port BB is connected to oil port BD of the oil circuit board, oil port BP is connected to oil port JB of the main pressure reducing valve, and oil port BT is connected to oil port KT of the oil circuit board.

[0013] The second two-position four-way solenoid valve includes ports CA, CB, CP and CT. Port CA is blocked, port CB is connected to port CD of the oil circuit board, port CP is connected to port JB of the main pressure reducing valve, and port CT is connected to port KT of the oil circuit board.

[0014] The second three-position four-way solenoid valve includes ports DA, DB, DP and DT. Port DA is connected to port DC of the oil circuit board, port DB is connected to port DD of the oil circuit board, port DP is connected to port JB of the main pressure reducing valve, and port DT is connected to port KT of the oil circuit board.

[0015] The third three-position four-way solenoid valve includes ports EA, EB, EP and ET. Port EA is connected to port EC of the oil circuit board, port EB is connected to port ED of the oil circuit board, port EP is connected to port KP of the oil circuit block, and port ET is connected to port KT of the oil circuit board.

[0016] The first damping two-way valve has ports KA, KB and KC, the second damping two-way valve has ports LA, LB and LC, the third damping two-way valve has ports MA, MB and MC, the fourth damping two-way valve has ports NA, NB and NC, and the fourth three-position four-way solenoid valve includes ports FA, FB, FP and FT.

[0017] The oil port KA of the first damping two-way valve and the oil port LA of the second damping two-way valve are connected to the oil port EC of the oil circuit block; the oil port MA of the third damping two-way valve and the oil port NA of the fourth damping two-way valve are connected to the oil port ED of the oil circuit block; the oil port KB of the first damping two-way valve and the oil port NB of the fourth damping two-way valve are connected to the oil port KT of the oil circuit block; the oil port LB of the second damping two-way valve, the oil port MB of the third damping two-way valve, and the oil port FP of the fourth three-position four-way solenoid valve are connected to the oil port KP of the oil circuit block; the oil port KC of the first damping two-way valve and the oil port MC of the third damping two-way valve are connected to the oil port FA of the fourth three-position four-way solenoid valve; the oil port LC of the second damping two-way valve and the oil port NC of the fourth damping two-way valve are connected to the oil port FB of the fourth three-position four-way solenoid valve; and the oil port FT of the fourth three-position four-way solenoid valve is connected to the oil port KL of the oil circuit block.

[0018] The actuator includes a first back pressure cylinder, a second back pressure cylinder, a third back pressure cylinder, a fourth back pressure cylinder, and a break-off cylinder. The rodless chambers of the first, second, third, and fourth back pressure cylinders are respectively connected to a first back pressure accumulator and a first pressure controller, a second back pressure accumulator and a second pressure controller, a third back pressure accumulator and a third pressure controller, and a fourth back pressure accumulator and a fourth pressure controller. The rodless chambers of the first, second, third, and fourth back pressure cylinders are also respectively connected to a first hydraulic check valve, a second hydraulic check valve, a third hydraulic check valve, and a fourth hydraulic check valve.

[0019] The rodless chamber of the first back pressure cylinder is connected to port BC on the oil circuit board through the first hydraulic check valve, the control port of the first hydraulic check valve is connected to port AD on the oil circuit board, and the rod chamber of the first back pressure cylinder is connected to port BD on the oil circuit board.

[0020] The rodless chamber of the second back pressure cylinder is connected to port BC on the oil circuit board through the second hydraulic control check valve, the control port of the second hydraulic control check valve is connected to port AD on the oil circuit board, and the rod chamber of the second back pressure cylinder is connected to port BD on the oil circuit board.

[0021] The rodless chamber of the third back pressure cylinder is connected to port DC on the oil circuit board through the third hydraulic control check valve, the control port of the third hydraulic control check valve is connected to port CD on the oil circuit board, and the rod chamber of the third back pressure cylinder is connected to port DD on the oil circuit board.

[0022] The rodless chamber of the fourth back pressure cylinder is connected to port DC on the oil circuit board through the fourth hydraulic control check valve, the control port of the fourth hydraulic control check valve is connected to port CD on the oil circuit board, and the rod chamber of the fourth back pressure cylinder is connected to port DD on the oil circuit board.

[0023] The rodless chamber of the expansion cylinder is connected to the oil port EC on the oil circuit board, and the rod chamber is connected to the oil port ED on the oil circuit board.

[0024] Furthermore, a one-way valve is connected between the oil outlet of the oil pump unit and the output port GP of the oil supply device, and an overflow valve is provided between the oil outlet of the oil pump unit and the oil tank; a first pressure gauge is connected to the output port GP of the oil supply device, and a second pressure gauge is connected to the oil outlet of the oil pump unit.

[0025] Furthermore, the output port GP of the oil supply device is connected to a safety valve assembly, and the safety valve assembly is located between the oil supply accumulator and the output port GP. The drain port of the safety valve assembly is connected to the oil tank.

[0026] Furthermore, a first one-way throttle valve is connected between port BA of the first three-position four-way solenoid valve and port BC of the manifold block, and between port BB and port BD. A second one-way throttle valve is connected between port DA of the second three-position four-way solenoid valve and port DC of the manifold block, and between port DB and port DD. A third one-way throttle valve is connected between port EA of the third three-position four-way solenoid valve and port EC of the manifold block, and between port EB and port ED. A one-way pressure reducing valve is provided between port EB and its corresponding third one-way throttle valve.

[0027] Furthermore, a first safety valve, connected in parallel with the first hydraulic check valve, is connected between the rodless chamber of the first back pressure cylinder and the oil port BC of the hydraulic circuit board; a second safety valve, connected in parallel with the second hydraulic check valve, is connected between the rodless chamber of the second back pressure cylinder and the oil port BC of the hydraulic circuit board; a third safety valve, connected in parallel with the third hydraulic check valve, is connected between the rodless chamber of the third back pressure cylinder and the oil port DC of the hydraulic circuit board; and a fourth safety valve, connected in parallel with the fourth hydraulic check valve, is connected between the rodless chamber of the fourth back pressure cylinder and the oil port DC of the hydraulic circuit board.

[0028] Furthermore, the oil tank is equipped with a level gauge, a level controller, an oil temperature controller, and an air filter.

[0029] A hydraulic control method for a fracture breaker, employing the aforementioned control system, specifically includes the following steps:

[0030] S1. Pressurize the oil supply device; start the oil pump unit, and the oil pump unit inputs the oil in the oil tank into the oil supply accumulator, so that the oil pump unit reaches the set pressure.

[0031] S2. Provide back pressure to the workpiece; the electromagnet YVBB of the first three-position four-way solenoid valve and the electromagnet YVDB of the second three-position four-way solenoid valve are simultaneously energized. The oil port BP of the first three-position four-way solenoid valve is connected to the oil port BA, and the oil port BT is connected to the oil port BB. The oil port DP of the second three-position four-way solenoid valve is connected to the oil port DA, and the oil port DT is connected to the oil port DB. The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the main pressure reducing valve, the oil ports BP and BA of the first three-position four-way solenoid valve, and the oil port BC of the oil circuit block. It then enters the rodless chamber of the first back pressure cylinder through the first hydraulic check valve, and the rodless chamber of the second back pressure cylinder through the second hydraulic check valve. At the same time, it passes through the oil ports DP and DA of the second three-position four-way solenoid valve, and the oil port DC of the oil circuit block. It then enters the rodless chamber of the third back pressure cylinder through the third hydraulic check valve, and the rodless chamber of the fourth back pressure cylinder through the fourth hydraulic check valve.

[0032] The oil in the rod chamber of the first back pressure cylinder and the oil in the rod chamber of the second back pressure cylinder return to the oil tank through the oil port BD of the oil circuit block, the oil port BB and the oil port BT of the first three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the oil return port GT of the oil supply device. The oil in the rod chamber of the third back pressure cylinder and the oil in the rod chamber of the fourth back pressure cylinder return to the oil tank through the oil port DD of the oil circuit block, the oil port DB and the oil port DT of the second three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the oil return port GT of the oil supply device.

[0033] When the pressure in the rodless chambers of the first, second, third, and fourth back pressure cylinders reaches the pressures set by the first, second, third, and fourth pressure controllers respectively, the solenoid YVBB of the first three-position four-way solenoid valve and the solenoid YVDB of the second three-position four-way solenoid valve are simultaneously de-energized and reset. The first, second, third, and fourth back pressure accumulators maintain the pressure, thereby providing back pressure to the workpiece.

[0034] S3. The expansion cylinder slowly descends; the electromagnet YVEB of the third three-position four-way solenoid valve is energized, and its oil port EP is connected to oil port EA, and its oil port ET is connected to oil port EB. The oil in the oil tank enters the rodless chamber of the expansion cylinder through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil ports EP and EA of the third three-position four-way solenoid valve, and the oil port EC of the oil circuit block; the oil in the rod chamber of the expansion cylinder returns to the oil tank through the oil port ED of the oil circuit block, the oil ports EB and ET of the third three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the return port GT of the oil supply device, and the piston rod of the expansion cylinder slowly extends.

[0035] S4. Rapidly break the workpiece; the electromagnet YVFB of the fourth three-position four-way solenoid valve is energized, its oil port FP is connected to oil port FA, and its oil port FT is connected to oil port FB. The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil port FP and oil port FA of the fourth three-position four-way solenoid valve and enters the oil port KC of the first damping two-way valve and the oil port MC of the third damping two-way valve. The first damping two-way valve and the third damping two-way valve are in the closed state. The oil port KA and oil port KB of the first damping two-way valve are disconnected, and the oil port MA and oil port MB of the third damping two-way valve are disconnected.

[0036] The oil from port LC of the second damping two-way valve and port NC of the fourth damping two-way valve returns to the oil tank through port FB, port FT of the fourth three-position four-way solenoid valve, port KL of the oil circuit block, and the drain port GL of the oil supply device. The second damping two-way valve and the fourth damping two-way valve open. Port LA of the second damping two-way valve is connected to port LB, and port NA and port NB of the fourth damping two-way valve are connected.

[0037] The oil in the oil tank enters the rodless chamber of the expansion cylinder through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil ports LB and LA of the second damping two-way valve, and the oil port EC of the oil circuit block. The oil in the rod chamber of the expansion cylinder returns to the oil tank through the oil port ED of the oil circuit block, the oil ports NA and NB of the fourth damping two-way valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device. The piston rod of the expansion cylinder extends rapidly to achieve the expansion and fracture of the workpiece. The first back pressure accumulator, the second back pressure accumulator, the third back pressure accumulator, and the fourth back pressure accumulator absorb the hydraulic shock during expansion and fracture.

[0038] S5, the expansion cylinder returns quickly; the electromagnet YVFA of the fourth three-position four-way solenoid valve is energized, its oil port FP is connected to oil port FB, and its oil port FT is connected to oil port FA. The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil port FP and oil port FB of the fourth three-position four-way solenoid valve and enters the oil port LC of the second damping two-way valve and the oil port NC of the fourth damping two-way valve. The second damping two-way valve and the fourth damping two-way valve are in the closed state. The oil port LA and oil port LB of the second damping two-way valve are disconnected, and the oil port NA and oil port NB of the fourth damping two-way valve are disconnected.

[0039] The oil from port KC of the first damping two-way valve and port MC of the third damping two-way valve returns to the oil tank through port FA, port FT of the fourth three-position four-way solenoid valve, port KL of the oil circuit block, and the drain port GL of the oil supply device. The first damping two-way valve and the third damping two-way valve are opened. Port KA of the first damping two-way valve is connected to port KB, and port MA and port MB of the third damping two-way valve are connected.

[0040] The oil in the oil tank enters the rod chamber of the expansion cylinder through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil ports MB and MA of the third damping two-way valve, and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder returns to the oil tank through the oil port EC of the oil circuit block, the oil ports KA and KB of the first damping two-way valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device. The piston rod of the expansion cylinder retracts rapidly.

[0041] S6. The expansion cylinder slowly returns to its starting position; the electromagnet YVEA of the third three-position four-way solenoid valve is energized, and its oil port EP is connected to oil port EB, and its oil port ET is connected to oil port EA. The oil in the oil tank enters the rod chamber of the expansion cylinder through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the oil ports EP and EB of the third three-position four-way solenoid valve, and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder returns to the oil tank through the oil port EC of the oil circuit block, the oil ports EA and ET of the third three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device. The piston rod of the expansion cylinder slowly retracts.

[0042] S7, back pressure cylinder depressurization; the solenoid YVAA of the first two-position four-way solenoid valve and the solenoid YVCA of the second two-position four-way solenoid valve are energized at the same time, the first three-position four-way solenoid valve and the second three-position four-way solenoid valve are in the middle position, the oil port AP and oil port AB of the first two-position four-way solenoid valve are connected, the oil port AT and oil port AA are connected, the oil port CP and oil port CB of the second two-position four-way solenoid valve are connected, and the oil port CT and oil port CA are connected.

[0043] The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the main pressure reducing valve, the oil ports AP and AB of the first and second position four-way solenoid valves, and the oil port AD of the oil circuit block, and enters the control ports of the first and second hydraulic control check valves. The first and second hydraulic control check valves are open. The oil in the rodless chamber of the first back pressure cylinder is output through the first hydraulic control check valve, and the oil in the rodless chamber of the second back pressure cylinder is output through the second hydraulic control check valve. The oil then returns to the oil tank through the oil port BC of the oil circuit block, the oil ports BA and BT of the first three position four-way solenoid valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device, thereby realizing the depressurization of the first and second back pressure cylinders.

[0044] The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the main pressure reducing valve, the oil ports CP and CB of the second two-position four-way solenoid valve, and the oil port CD of the oil circuit block, and enters the control ports of the third and fourth hydraulically controlled check valves. The third and fourth hydraulically controlled check valves are open. The oil in the rodless chamber of the third back pressure cylinder is output through the third hydraulically controlled check valve, and the oil in the rodless chamber of the fourth back pressure cylinder is output through the fourth hydraulically controlled check valve. The oil then returns to the oil tank through the oil port DC of the oil circuit block, the oil ports DA and DT of the second three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device, thereby realizing the pressure relief of the third and fourth back pressure cylinders.

[0045] S8. Back pressure cylinder reset; the solenoids YVAA of the first two-position four-way solenoid valve, YVBA of the first three-position four-way solenoid valve, YVCA of the second two-position four-way solenoid valve, and YVDA of the second three-position four-way solenoid valve are simultaneously energized. The oil port AP of the first two-position four-way solenoid valve is connected to the oil port AB, and the oil port AT is connected to the oil port AA. The oil port BP of the first three-position four-way solenoid valve is connected to the oil port BB, and the oil port BT is connected to the oil port BA. The oil port CP of the second two-position four-way solenoid valve is connected to the oil port CB, and the oil port CT is connected to the oil port CA. The oil port DP of the second three-position four-way solenoid valve is connected to the oil port DB, and the oil port DT is connected to the oil port DA. The first hydraulic control check valve, the second hydraulic control check valve, the third hydraulic control check valve, and the fourth hydraulic control check valve open.

[0046] The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the main pressure reducing valve, the oil ports BP, BB of the first three-position four-way solenoid valve, and the oil port BD of the oil circuit block, respectively entering the rod chamber of the first back pressure cylinder and the rod chamber of the second back pressure cylinder. The oil in the rodless chamber of the first back pressure cylinder is output through the first hydraulic control check valve, and the oil in the rodless chamber of the second back pressure cylinder is output through the second hydraulic control check valve. The oil returns to the oil tank through the oil port BC of the oil circuit block, the oil ports BA, BT of the first three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device. The first back pressure cylinder and the fourth back pressure cylinder are reset.

[0047] The oil in the oil tank passes through the oil pump unit, the output port GP of the oil supply device, the oil port KP of the oil circuit block, the main pressure reducing valve, the oil ports DP and DB of the second three-position four-way solenoid valve, and the oil port DD of the oil circuit block, respectively, and enters the rod chamber of the third back pressure cylinder and the rod chamber of the fourth back pressure cylinder. The oil in the rodless chamber of the third back pressure cylinder is output through the third hydraulic control check valve, and the oil in the rodless chamber of the fourth back pressure cylinder is output through the fourth hydraulic control check valve. The oil returns to the oil tank through the oil port DC of the oil circuit block, the oil ports DA and DT of the second three-position four-way solenoid valve, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device. The third and fourth back pressure cylinders are then reset.

[0048] In summary, the present invention has the following beneficial effects:

[0049] 1. The control system of the present invention forms a symmetrical back pressure safety hydraulic circuit, which can absorb the impact force when the expansion machine is working, ensure the safety and reliability of the expansion machine operation, reduce the scrap rate, increase the service life of the expansion machine and the product yield, reduce production costs and increase production efficiency.

[0050] 2. During operation, the present invention sequentially performs the following steps: pressurization of the oil supply device, application of back pressure to the workpiece, slow descent of the expansion cylinder, rapid expansion of the workpiece, rapid return of the expansion cylinder, slow return of the expansion cylinder, depressurization of the back pressure cylinder, and resetting of the back pressure cylinder. This ensures the expansion effect on the workpiece and guarantees product quality, while also preventing the rapid operation of the expansion cylinder from affecting its service life and ensuring the safe and reliable operation of the expansion machine. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of a hydraulic control system for a fracture breaker;

[0052] Figure 2 This is a flowchart of a hydraulic control method for a fracture breaker.

[0053] In the diagram, 01 is the oil supply device; 02 is the control valve group; 03 is the actuator; 1 is the oil tank; 2 is the level gauge; 3 is the level controller; 4 is the oil temperature controller; 5 is the air filter; 6 is the oil pump unit; 7 is the oil supply check valve; 8 is the overflow valve; 9 is the oil supply accumulator; 10 is the safety valve group; 11 is the first pressure gauge; 12 is the second pressure gauge; 13 is the oil circuit board; 14 is the main pressure reducing valve; 15 is the first two-position four-way solenoid valve; 16 is the first three-position four-way solenoid valve; 17 is the first one-way throttle valve; 18 is the second two-position four-way solenoid valve; 19 is the second three-position four-way solenoid valve; 20 is the second one-way throttle valve; 21 is the third three-position four-way solenoid valve; 22 is the one-way pressure reducing valve; 23 is the third one-way throttle valve; 24 is the first damping two-way valve; 25 is the second damping two-way valve. 26. Third damping two-way valve; 27. Fourth damping two-way valve; 28. Fourth three-position four-way solenoid valve; 29. ​​First back pressure cylinder; 30. Second back pressure cylinder; 31. Third back pressure cylinder; 32. Fourth back pressure cylinder; 33. First hydraulically controlled check valve; 34. First safety valve; 35. First back pressure accumulator; 36. First pressure controller; 37. Second hydraulically controlled check valve; 38. Second safety valve; 39. Second back pressure accumulator; 40. Second pressure controller; 41. Third hydraulically controlled check valve; 42. Third safety valve; 43. Third back pressure accumulator; 44. Third pressure controller; 45. Fourth hydraulically controlled check valve; 46. Fourth safety valve; 47. Fourth back pressure accumulator; 48. Fourth pressure controller; 49. Expansion cylinder. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0055] A hydraulic control system for a fracture breaker, such as Figure 1 As shown, the device includes an oil supply unit 01, a control valve assembly 02, and an actuator 03. The oil supply unit 01 supplies oil to the actuator 03 through the control valve assembly 02, controlling the actuator 03 to perform extension and retraction movements. All subsequent oil circuits are connected via pipelines. Specifically, as shown... Figure 1 As shown, the oil supply device 01 includes an oil tank 1. The oil tank 1 is equipped with a level gauge 2, a level controller 3, an oil temperature controller 4, and an air filter 5. The level gauge 2 and level controller 3 work together to ensure sufficient oil in the oil tank 1, the oil temperature controller 4 ensures a suitable oil temperature in the oil tank 1, and the air filter 5 ensures the cleanliness of the oil in the oil tank 1. The oil supply device 01 is equipped with an output port GP, an oil return port GT, and an oil drain port GL. Both the oil return port GT and the oil drain port GL are directly connected to the oil tank 1.

[0056] like Figure 1As shown, the oil supply device 01 also includes an oil pump unit 6. The oil inlet of the oil pump unit 6 is connected to the oil tank 1, and the oil outlet is connected to the output port GP through an oil supply check valve 7. The oil pump unit 6 outputs oil from the oil tank 1 to the output port GP. The oil supply device 01 outputs oil to the control valve group 02 through the output port GP. The oil supply check valve 7 can prevent oil backflow. An overflow valve 8 is also provided between the oil outlet of the oil pump unit 6 and the oil tank 1, and a second pressure gauge 12 is connected to the oil outlet of the oil pump unit 6. The overflow valve 8 and the second pressure gauge 12 work together to protect the oil pump unit 6. The output port GP of the oil supply device 01 is also connected to an oil supply accumulator 9, a first pressure gauge 11, and a safety valve group 10. The safety valve group 10 is located between the oil supply accumulator 9 and the output port GP, and the drain port of the safety valve group 10 is connected to the oil tank 1.

[0057] like Figure 1 As shown, the control valve assembly 02 includes an oil circuit board 13, which has oil ports KP, KT, KL, AD, BC, BD, CD, DC, DD, EC, and ED. Oil port KP is connected to the output port GP of the oil supply device 01, oil port KT is connected to the return port GT of the oil supply device 01, oil port KL is connected to the drain port GL of the oil supply device 01, and oil ports AD, BC, BD, CD, DC, DD, EC, and ED are connected to the actuator 03. The control valve assembly 02 also includes a main pressure reducing valve 14, a first two-position four-way solenoid valve 15, a first three-position four-way solenoid valve 16, a second two-position four-way solenoid valve 18, a second three-position four-way solenoid valve 19, a third three-position four-way solenoid valve 21, a first damping two-way valve 24, a second damping two-way valve 25, a third damping two-way valve 26, a fourth damping two-way valve 27, and a fourth three-position four-way solenoid valve 28.

[0058] Specifically, such as Figure 1 As shown, the main pressure reducing valve 14 includes ports JA, JB, and JC. Port JA is connected to port KP of the oil circuit board 13, and port JC is connected to port KL of the oil circuit board 13. The first and second position four-way solenoid valve 15 includes ports AA, AB, AP, and AT. Port AA is blocked, port AB is connected to port AD of the oil circuit board 13, port AP is connected to port JB of the main pressure reducing valve 14, and port AT is connected to port KT of the oil circuit board 13. The first and third position four-way solenoid valve 16 includes ports BA, BB, BP, and BT. Port BP is connected to port JB of the main pressure reducing valve 14, port BT is connected to port KT of the oil circuit board 13, port BA is connected to port BC of the oil circuit board 13, and port BB is connected to port BD of the oil circuit board 13. A first one-way throttle valve 17 is connected between ports BA and BC, and between ports BB and BD.

[0059] like Figure 1As shown, the second two-position four-way solenoid valve 18 includes ports CA, CB, CP, and CT. Port CA is blocked. Port CB is connected to port CD of the oil circuit board 13. Port CP is connected to port JB of the main pressure reducing valve 14. Port CT is connected to port KT of the oil circuit board 13. The second three-position four-way solenoid valve 19 includes ports DA, DB, DP, and DT. Port DP is connected to port JB of the main pressure reducing valve 14. Port DT is connected to port KT of the oil circuit board 13. Port DA is connected to port DC of the oil circuit board 13. Port DB is connected to port DD of the oil circuit board 13. A second one-way throttle valve 20 is connected between ports DA and DC, and between ports DB and DD. The third three-position four-way solenoid valve 21 includes oil ports EA, EB, EP and ET. Oil port EP is connected to oil port KP of the oil circuit block, oil port ET is connected to oil port KT of the oil circuit board 13, oil port EA is connected to oil port EC of the oil circuit board 13, oil port EB is connected to oil port ED of the oil circuit board 13, and a third one-way throttle valve 23 is connected between oil port EA and oil port EC, and between oil port EB and oil port ED. A one-way pressure reducing valve 22 is provided between oil port EB and its corresponding third one-way throttle valve 23.

[0060] like Figure 1 As shown, the first damping two-way valve 24 has oil ports KA, KB and KC, the second damping two-way valve 25 has oil ports LA, LB and LC, the third damping two-way valve 26 has oil ports MA, MB and MC, the fourth damping two-way valve 27 has oil ports NA, NB and NC, and the fourth three-position four-way solenoid valve 28 includes oil ports FA, FB, FP and FT.

[0061] Specifically, such as Figure 1 As shown, port KA of the first damping two-way valve 24 and port LA of the second damping two-way valve 25 are connected to port EC of the manifold block. Port MA of the third damping two-way valve 26 and port NA of the fourth damping two-way valve 27 are connected to port ED of the manifold block. Port KB of the first damping two-way valve 24 and port NB of the fourth damping two-way valve 27 are connected to port KT of the manifold block. Port LB of the second damping two-way valve 25, port MB of the third damping two-way valve 26, and port FP of the fourth three-position four-way solenoid valve 28 are connected to port KP of the manifold block. The oil port KC of the first damping two-way valve 24, the oil port MC of the third damping two-way valve 26, and the oil port FA of the fourth three-position four-way solenoid valve 28 are connected. The oil port LC of the second damping two-way valve 25, the oil port NC of the fourth damping two-way valve 27, and the oil port FB of the fourth three-position four-way solenoid valve 28 are connected. The oil port FT of the fourth three-position four-way solenoid valve 28 is connected to the oil port KL of the oil circuit block.

[0062] like Figure 1As shown, the actuator 03 includes a first back pressure cylinder 29, a second back pressure cylinder 30, a third back pressure cylinder 31, a fourth back pressure cylinder 32, and a break-off cylinder 49. Unless otherwise specified, the first back pressure cylinder 29, the second back pressure cylinder 30, the third back pressure cylinder 31, and the fourth back pressure cylinder 32 are collectively referred to as back pressure cylinders. The four back pressure cylinders are symmetrically arranged, with the workpiece located between them. The piston rods of all four back pressure cylinders face the workpiece, and the first and second back pressure cylinders 29 and 30 are located on the same side, as are the third and fourth back pressure cylinders 31 and 32. The rodless chamber of the break-off cylinder 49 is connected to the oil port EC on the hydraulic circuit board 13, and the rod chamber is connected to the oil port ED on the hydraulic circuit board 13.

[0063] like Figure 1 As shown, the rodless chamber of the first back pressure cylinder 29 is connected to the first back pressure accumulator 35 and the first pressure controller 36. The rodless chamber of the first back pressure cylinder 29 is connected to the oil port BC on the oil circuit board 13 through the first hydraulic control check valve 33 and the first safety valve 34 connected in parallel. The control oil port of the first hydraulic control check valve 33 is connected to the oil port AD on the oil circuit board 13. The rod chamber of the first back pressure cylinder 29 is connected to the oil port BD on the oil circuit board 13.

[0064] like Figure 1 As shown, the rodless chamber of the second back pressure cylinder 30 is connected to the second back pressure accumulator 39 and the second pressure controller 40. The rodless chamber of the second back pressure cylinder 30 is connected to the oil port BC on the oil circuit board 13 through the parallel second hydraulic control check valve 37 and the second safety valve 38. The control oil port of the second hydraulic control check valve 37 is connected to the oil port AD on the oil circuit board 13. The rod chamber of the second back pressure cylinder 30 is connected to the oil port BD on the oil circuit board 13.

[0065] like Figure 1 As shown, the rodless chamber of the third back pressure cylinder 31 is connected to the third back pressure accumulator 43 and the third pressure controller 44. The rodless chamber of the third back pressure cylinder 31 is connected to the oil port DC on the oil circuit board 13 through the parallel third hydraulic control check valve 41 and the third safety valve 42. The control oil port of the third hydraulic control check valve 41 is connected to the oil port CD on the oil circuit board 13. The rod chamber of the third back pressure cylinder 31 is connected to the oil port DD on the oil circuit board 13.

[0066] like Figure 1 As shown, the rodless chamber of the fourth back pressure cylinder 32 is connected to the fourth back pressure accumulator 47 and the fourth pressure controller 48. The rodless chamber of the fourth back pressure cylinder 32 is connected to the oil port DC on the oil circuit board 13 through the parallel fourth hydraulic control check valve 45 and the fourth safety valve 46. The control oil port of the fourth hydraulic control check valve 45 is connected to the oil port CD on the oil circuit board 13. The rod chamber of the fourth back pressure cylinder 32 is connected to the oil port DD on the oil circuit board 13.

[0067] The control system of this invention forms a symmetrical back pressure safety hydraulic circuit, which can absorb the impact force when the expansion machine is working, ensure the safety and reliability of the expansion machine operation, reduce the scrap rate, increase the service life of the expansion machine and the product yield, reduce production costs and increase production efficiency.

[0068] A hydraulic control method for a fracture breaker, employing the aforementioned control system, such as... Figure 1 and Figure 2 As shown, the specific steps include the following:

[0069] S1, Oil supply device 01 pressure build-up; Start the oil pump unit 6. The oil pump unit 6 draws oil from the oil tank 1. The oil is fed into the oil supply accumulator 9 through the oil outlet of the oil pump unit 6 and the oil supply check valve 7, so that the oil pump unit 6 reaches the set pressure.

[0070] S2. Provide back pressure to the workpiece; The electromagnet YVBB of the first three-position four-way solenoid valve 16 and the electromagnet YVDB of the second three-position four-way solenoid valve 19 are simultaneously energized. The oil port BP of the first three-position four-way solenoid valve is connected to the oil port BA, and the oil port BT is connected to the oil port BB. The oil port DP of the second three-position four-way solenoid valve 19 is connected to the oil port DA, and the oil port DT is connected to the oil port DB. At this time, the oil is input into the rodless chambers of the four back pressure cylinders through the first three-way four-position solenoid valve, the first hydraulic check valve 33, and the second hydraulic check valve 37. Specifically, the oil from the oil tank 1 passes through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the main pressure reducing valve 14, the oil ports BP and BA of the first three-way four-position solenoid valve, and the oil port BC of the oil circuit block. It then enters the rodless chamber of the first back pressure cylinder 29 through the first hydraulic check valve 33 and the rodless chamber of the second back pressure cylinder 30 through the second hydraulic check valve 37. At the same time, it passes through the oil ports DP and DA of the second three-way four-position solenoid valve and the oil port DC of the oil circuit block. It then enters the rodless chamber of the third back pressure cylinder 31 through the third hydraulic check valve 41 and the rodless chamber of the fourth back pressure cylinder 32 through the fourth hydraulic check valve 45.

[0071] The oil return from the rod chambers of the four back pressure cylinders is as follows: the oil from the rod chamber of the first back pressure cylinder 29 and the oil from the rod chamber of the second back pressure cylinder 30 return to the oil tank 1 via the oil port BD of the oil circuit block, the oil ports BB and BT of the first three-position four-way solenoid valve 16, the oil port KT of the oil circuit block, and the return oil port GT of the oil supply device 01; the oil from the rod chambers of the third back pressure cylinder 31 and the fourth back pressure cylinder 32 return to the oil tank 1 via the oil port DD of the oil circuit block, the oil ports DB and DT of the second three-position four-way solenoid valve 19, the oil port KT of the oil circuit block, and the return oil port GT of the oil supply device 01.

[0072] When the pressure in the rodless chambers of the first back pressure cylinder 29, the second back pressure cylinder 30, the third back pressure cylinder 31, and the fourth back pressure cylinder 32 all reach the pressures set by the first pressure controller 36, the second pressure controller 40, the third pressure controller 44, and the fourth pressure controller 48, respectively, the electromagnet YVBB of the first three-position four-way solenoid valve 16 and the electromagnet YVDB of the second three-position four-way solenoid valve 19 are simultaneously de-energized and reset. The pressure is maintained by the first back pressure accumulator 35, the second back pressure accumulator 39, the third back pressure accumulator 43, and the fourth back pressure accumulator 47, thereby providing back pressure to the workpiece.

[0073] S3, the expansion cylinder 49 slowly descends; When the electromagnet YVEB of the third-position four-way solenoid valve 21 is energized, its oil port EP connects to oil port EA, and its oil port ET connects to oil port EB. Oil then enters the rodless chamber of the expansion cylinder 49 through the third-position four-way solenoid valve. Specifically, oil from tank 1 passes through oil pump unit 6, the output port GP of oil supply device 01, the oil port KP of the oil circuit block, the oil ports EP and EA of the third-position four-way solenoid valve 21, and the oil port EC of the oil circuit block, entering the rodless chamber of the expansion cylinder 49. Oil in the rod chamber of the expansion cylinder 49 returns through the third-position four-way solenoid valve 21. Specifically, oil in the rod chamber of the expansion cylinder 49 returns to tank 1 through the oil port ED of the oil circuit block, the oil ports EB and ET of the third-position four-way solenoid valve 21, the oil port KT of the oil circuit block, and the return port GT of the oil supply device 01. The piston rod of the expansion cylinder 49 then slowly extends.

[0074] S4. Rapidly fractures the workpiece; When the electromagnet YVFB of the fourth three-position four-way solenoid valve 28 is energized, its oil port FP is connected to oil port FA, and its oil port FT is connected to oil port FB. First, the second damping two-way valve 25 and the fourth damping two-way valve 27 are opened through the fourth three-position four-way solenoid valve 28. The specific oil inlet process is as follows: the oil in the oil tank 1 passes through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the oil port FP and the oil port FA of the fourth three-position four-way solenoid valve 28 and enters the oil port KC of the first damping two-way valve 24 and the oil port MC of the third damping two-way valve 26. The first damping two-way valve 24 and the third damping two-way valve 26 are in the closed state. The oil port KA and the oil port KB of the first damping two-way valve 24 are disconnected, and the oil port MA and the oil port MB of the third damping two-way valve 26 are disconnected.

[0075] The specific oil return process is as follows: the oil from port LC of the second damping two-way valve 25 and port NC of the fourth damping two-way valve 27 returns to the oil tank 1 through port FB, port FT of the fourth three-position four-way solenoid valve 28, port KL of the oil circuit block, and the drain port GL of the oil supply device 01. The second damping two-way valve 25 and the fourth damping two-way valve 27 are opened. Port LA of the second damping two-way valve 25 is connected to port LB, and port NA of the fourth damping two-way valve 27 is connected to port NB.

[0076] Next, the oil enters the rodless chamber of the expansion cylinder 49 through the second damping two-way valve 25. Specifically, the oil from tank 1 enters the rodless chamber of the expansion cylinder 49 through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the oil ports LB and LA of the second damping two-way valve 25, and the oil port EC of the oil circuit block. The oil in the rod chamber of the expansion cylinder 49 returns through the fourth damping two-way valve 27. Specifically, the oil in the rod chamber of the expansion cylinder 49 returns to tank 1 through the oil port ED of the oil circuit block, the oil ports NA and NB of the fourth damping two-way valve 27, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device 01.

[0077] This allows the piston rod of the expansion cylinder 49 to extend rapidly, achieving the expansion and fracture of the workpiece. The first back pressure accumulator 35, the second back pressure accumulator 39, the third back pressure accumulator 43, and the fourth back pressure accumulator 47 absorb the hydraulic shock during expansion and fracture. The first safety valve 34, the second safety valve 38, the third safety valve 42, and the fourth safety valve 46 provide safety overflow protection during the instantaneous increase of impact pressure.

[0078] S5, Expansion Cylinder 49 Quick Return; When the electromagnet YVFA of the fourth three-position four-way solenoid valve 28 is energized, its oil port FP is connected to oil port FB, and its oil port FT is connected to oil port FA. First, the first damping two-way valve 24 and the third damping two-way valve 26 are opened through the fourth three-position four-way solenoid valve 28. The specific oil inlet process is as follows: the oil in the oil tank 1 passes through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the oil port FP and the oil port FB of the fourth three-position four-way solenoid valve 28 and enters the oil port LC of the second damping two-way valve 25 and the oil port NC of the fourth damping two-way valve 27. The second damping two-way valve 25 and the fourth damping two-way valve 27 are in the closed state. The oil port LA and the oil port LB of the second damping two-way valve 25 are disconnected, and the oil port NA and the oil port NB of the fourth damping two-way valve 27 are disconnected.

[0079] The specific oil return process is as follows: the oil from port KC of the first damping two-way valve 24 and port MC of the third damping two-way valve 26 returns to the oil tank 1 through port FA and port FT of the fourth three-position four-way solenoid valve 28, port KL of the oil circuit block, and the drain port GL of the oil supply device 01. The first damping two-way valve 24 and the third damping two-way valve 26 are opened. Port KA of the first damping two-way valve 24 is connected to port KB, and port MA of the third damping two-way valve 26 is connected to port MB.

[0080] Next, the oil enters the rod chamber of the expansion cylinder 49 through the third damping two-way valve 26. Specifically, the oil in the oil tank 1 enters the rod chamber of the expansion cylinder 49 through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the oil ports MB and MA of the third damping two-way valve 26, and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder 49 returns through the first damping two-way valve 24. Specifically, the oil in the rodless chamber of the expansion cylinder 49 returns to the oil tank 1 through the oil port EC of the oil circuit block, the oil ports KA and KB of the first damping two-way valve 24, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device 01. The piston rod of the expansion cylinder 49 then retracts rapidly.

[0081] S6, Expansion Cylinder 49 Slow Return; When the electromagnet YVEA of the third-position four-way solenoid valve 21 is energized, its oil port EP connects to oil port EB, and its oil port ET connects to oil port EA. The oil in the oil tank 1 enters the rod chamber of the expansion cylinder 49 through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the oil ports EP and EB of the third-position four-way solenoid valve 21, and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder 49 returns to the oil tank 1 through the oil port EC of the oil circuit block, the oil ports EA and ET of the third-position four-way solenoid valve 21, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device 01. The piston rod of the expansion cylinder 49 retracts slowly.

[0082] S7, back pressure cylinder pressure relief; The electromagnets YVAA of the first and second position four-way solenoid valve 15 and YVCA of the second and second position four-way solenoid valve 18 are simultaneously energized. The first and second position four-way solenoid valves 16 and 19 are in the neutral position. The oil ports AP and AB of the first and second position four-way solenoid valves 15 are connected, and the oil ports AT and AA are connected. The oil ports CP and CB of the second and second position four-way solenoid valve 18 are connected, and the oil ports CT and CA are connected.

[0083] Oil from tank 1 flows through oil pump unit 6, the output port GP of oil supply device 01, the port KP of oil circuit block, the main pressure reducing valve 14, the ports AP and AB of the first two-position four-way solenoid valve 15, and the port AD of oil circuit block into the control ports of the first hydraulic control check valve 33 and the second hydraulic control check valve 37, thereby opening the first hydraulic control check valve 33 and the second hydraulic control check valve 37. Oil from the rodless chamber of the first back pressure cylinder 29 is output through the first hydraulic control check valve 33, and oil from the rodless chamber of the second back pressure cylinder 30 is output through the second hydraulic control check valve 37. The oil then returns to tank 1 through the ports BC of oil circuit block, the ports BA and BT of the first three-position four-way solenoid valve 16, the port KT of oil circuit block, and the drain port GT of oil supply device 01, thus depressurizing the first back pressure cylinder 29 and the second back pressure cylinder 30.

[0084] Oil from tank 1 flows through oil pump unit 6, the output port GP of oil supply device 01, the port KP of oil circuit block, the main pressure reducing valve 14, the ports CP and CB of the second two-position four-way solenoid valve 18, and the port CD of oil circuit block into the control ports of the third hydraulic control check valve 41 and the fourth hydraulic control check valve 45, thereby opening the third hydraulic control check valve 41 and the fourth hydraulic control check valve 45. Oil from the rodless chamber of the third back pressure cylinder 31 is output through the third hydraulic control check valve 41, and oil from the rodless chamber of the fourth back pressure cylinder 32 is output through the fourth hydraulic control check valve 45. The oil then returns to tank 1 through the port DC of oil circuit block, the ports DA and DT of the second three-position four-way solenoid valve 19, the port KT of oil circuit block, and the drain port GT of oil supply device 01, thus depressurizing the third back pressure cylinder 31 and the fourth back pressure cylinder 32.

[0085] S8, Back pressure cylinder reset; The solenoids YVAA of the first and second position four-way solenoid valve 15, YVBA of the first and third position four-way solenoid valve 16, YVCA of the second and third position four-way solenoid valve 18, and YVDA of the second and third position four-way solenoid valve 19 are simultaneously energized. The oil port AP of the first and second position four-way solenoid valve 15 is connected to the oil port AB, and the oil port AT is connected to the oil port AA. The oil port BP of the first and third position four-way solenoid valve 16 is connected to the oil port BB, and the oil port BT is connected to the oil port BA. The oil port CP of the second and second position four-way solenoid valve 18 is connected to the oil port CB, and the oil port CT is connected to the oil port CA. The oil port DP of the second and third position four-way solenoid valve 19 is connected to the oil port DB, and the oil port DT is connected to the oil port DA. Through the first and second position four-way solenoid valves 15 and 18, the first hydraulic control check valve 33, the second hydraulic control check valve 37, the third hydraulic control check valve 41, and the fourth hydraulic control check valve 45 are opened.

[0086] The oil in the oil tank 1 enters the rod chamber of the first back pressure cylinder 29 and the rod chamber of the second back pressure cylinder 30 through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the main pressure reducing valve 14, the oil ports BP, BB of the first three-position four-way solenoid valve 16, and the oil port BD of the oil circuit block, respectively. The oil in the rodless chamber of the first back pressure cylinder 29 is output through the first hydraulic control check valve 33, and the oil in the rodless chamber of the second back pressure cylinder 30 is output through the second hydraulic control check valve 37. The oil returns to the oil tank 1 through the oil port BC of the oil circuit block, the oil ports BA, BT of the first three-position four-way solenoid valve 16, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device 01. The first back pressure cylinder 29 and the fourth back pressure cylinder 32 are reset.

[0087] The oil in tank 1 flows through the oil pump unit 6, the output port GP of the oil supply device 01, the oil port KP of the oil circuit block, the main pressure reducing valve 14, the oil ports DP and DB of the second three-position four-way solenoid valve 19, and the oil port DD of the oil circuit block into the rod chamber of the third back pressure cylinder 31 and the rod chamber of the fourth back pressure cylinder 32, respectively. The oil in the rodless chamber of the third back pressure cylinder 31 is output through the third hydraulic control check valve 41, and the oil in the rodless chamber of the fourth back pressure cylinder 32 is output through the fourth hydraulic control check valve 45. The oil then returns to tank 1 through the oil port DC of the oil circuit block, the oil ports DA and DT of the second three-position four-way solenoid valve 19, the oil port KT of the oil circuit block, and the drain port GT of the oil supply device 01. The third back pressure cylinder 31 and the fourth back pressure cylinder 32 are then reset.

[0088] During operation, the present invention sequentially performs the following steps: pressure building by the oil supply device 01, providing back pressure to the workpiece, slow downward movement of the expansion cylinder 49, rapid expansion of the workpiece, rapid return of the expansion cylinder 49, slow return of the expansion cylinder 49, pressure release of the back pressure cylinder, and reset of the back pressure cylinder. This ensures both the expansion effect on the workpiece and product quality, while also preventing the rapid operation of the expansion cylinder 49 from affecting its service life, thus ensuring the safe and reliable operation of the expansion machine.

[0089] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A hydraulic control system for a fracture breaker, characterized in that: It includes an oil supply device (01), a control valve group (02), and an actuator (03). The oil supply device (01) supplies oil to the actuator (03) through the control valve group (02) and controls the actuator (03) to perform extension and retraction movements. The oil supply device (01) includes an oil tank (1) and an oil pump unit (6). The oil supply device (01) is provided with an output port GP, an oil return port GT and an oil drain port GL. The oil return port GT and the oil drain port GL are both connected to the oil tank (1). The output port GP is connected to an oil supply accumulator (9). The oil inlet of the oil pump unit (6) is connected to the oil tank (1), and the oil outlet is connected to the output port GP. The control valve group (02) includes an oil circuit board (13), which is provided with oil ports KP, KT, KL, AD, BC, BD, CD, DC, DD, EC and ED. Oil port KP is connected to the output port GP of the oil supply device (01), oil port KT is connected to the return port GT of the oil supply device (01), oil port KL is connected to the drain port GL of the oil supply device (01), and oil ports AD, BC, BD, CD, DC, DD, EC and ED are connected to the actuator (03). The control valve group (02) also includes a main pressure reducing valve (14), a first two-position four-way solenoid valve (15), a first three-position four-way solenoid valve (16), a second two-position four-way solenoid valve (18), a second three-position four-way solenoid valve (19), a third three-position four-way solenoid valve (21), a first damping two-way valve (24), a second damping two-way valve (25), a third damping two-way valve (26), a fourth damping two-way valve (27), and a fourth three-position four-way solenoid valve (28). The main pressure reducing valve (14) includes oil ports JA, JB and JC. Oil port JA is connected to oil port KP of the oil circuit board (13), and oil port JC is connected to oil port KL of the oil circuit board (13). The first two-position four-way solenoid valve (15) includes oil ports AA, AB, AP and AT. Oil port AA is blocked, oil port AB is connected to oil port AD of oil circuit board (13), oil port AP is connected to oil port JB of main pressure reducing valve (14), and oil port AT is connected to oil port KT of oil circuit board (13). The first three-position four-way solenoid valve (16) includes oil ports BA, BB, BP and BT. Oil port BA is connected to oil port BC of oil circuit board (13), oil port BB is connected to oil port BD of oil circuit board (13), oil port BP is connected to oil port JB of main pressure reducing valve (14), and oil port BT is connected to oil port KT of oil circuit board (13). The second two-position four-way solenoid valve (18) includes oil ports CA, CB, CP and CT. Oil port CA is blocked, oil port CB is connected to oil port CD of oil circuit board (13), oil port CP is connected to oil port JB of main pressure reducing valve (14), and oil port CT is connected to oil port KT of oil circuit board (13). The second three-position four-way solenoid valve (19) includes oil ports DA, DB, DP and DT. Oil port DA is connected to oil port DC of oil circuit board (13), oil port DB is connected to oil port DD of oil circuit board (13), oil port DP is connected to oil port JB of main pressure reducing valve (14), and oil port DT is connected to oil port KT of oil circuit board (13). The third three-position four-way solenoid valve (21) includes oil ports EA, EB, EP and ET. Oil port EA is connected to oil port EC of oil circuit board (13), oil port EB is connected to oil port ED of oil circuit board (13), oil port EP is connected to oil port KP of oil circuit block, and oil port ET is connected to oil port KT of oil circuit board (13). The first damping two-way valve (24) has oil ports KA, KB and KC, the second damping two-way valve (25) has oil ports LA, LB and LC, the third damping two-way valve (26) has oil ports MA, MB and MC, the fourth damping two-way valve (27) has oil ports NA, NB and NC, and the fourth three-position four-way solenoid valve (28) includes oil ports FA, FB, FP and FT; The oil port KA of the first damping two-way valve (24) and the oil port LA of the second damping two-way valve (25) are connected to the oil port EC of the oil circuit block; the oil port MA of the third damping two-way valve (26) and the oil port NA of the fourth damping two-way valve (27) are connected to the oil port ED of the oil circuit block; the oil port KB of the first damping two-way valve (24) and the oil port NB of the fourth damping two-way valve (27) are connected to the oil port KT of the oil circuit block; the oil port LB of the second damping two-way valve (25) and the oil port MB of the third damping two-way valve (26) are connected to the oil port EC of the oil circuit block. The oil port FP of the fourth three-position four-way solenoid valve (28) is connected to the oil port KP of the oil circuit block; the oil port KC of the first damping two-way valve (24) and the oil port MC of the third damping two-way valve (26) are connected to the oil port FA of the fourth three-position four-way solenoid valve (28); the oil port LC of the second damping two-way valve (25) and the oil port NC of the fourth damping two-way valve (27) are connected to the oil port FB of the fourth three-position four-way solenoid valve (28); and the oil port FT of the fourth three-position four-way solenoid valve (28) is connected to the oil port KL of the oil circuit block. The actuator (03) includes a first back pressure cylinder (29), a second back pressure cylinder (30), a third back pressure cylinder (31), a fourth back pressure cylinder (32), and a break-off cylinder (49). The rodless chambers of the first back pressure cylinder (29), the second back pressure cylinder (30), the third back pressure cylinder (31), and the fourth back pressure cylinder (32) are respectively connected to a first back pressure accumulator (35) and a first pressure controller (36), and the second back pressure accumulator (39) and a second pressure controller (49). The controller (40), the third back pressure accumulator (43) and the third pressure controller (44), the fourth back pressure accumulator (47) and the fourth pressure controller (48), and the rodless chambers of the first back pressure cylinder (29), the second back pressure cylinder (30), the third back pressure cylinder (31) and the fourth back pressure cylinder (32) are respectively connected to the first hydraulic control check valve (33), the second hydraulic control check valve (37), the third hydraulic control check valve (41) and the fourth hydraulic control check valve (45) corresponding to them; The rodless chamber of the first back pressure cylinder (29) is connected to the oil port BC on the oil circuit board (13) through the first hydraulic control check valve (33), the control oil port of the first hydraulic control check valve (33) is connected to the oil port AD on the oil circuit board (13), and the rod chamber of the first back pressure cylinder (29) is connected to the oil port BD on the oil circuit board (13). The rodless chamber of the second back pressure cylinder (30) is connected to the oil port BC on the oil circuit board (13) through the second hydraulic control check valve (37), the control oil port of the second hydraulic control check valve (37) is connected to the oil port AD on the oil circuit board (13), and the rod chamber of the second back pressure cylinder (30) is connected to the oil port BD on the oil circuit board (13). The rodless chamber of the third back pressure cylinder (31) is connected to the oil port DC on the oil circuit board (13) through the third hydraulic control check valve (41), the control oil port of the third hydraulic control check valve (41) is connected to the oil port CD on the oil circuit board (13), and the rod chamber of the third back pressure cylinder (31) is connected to the oil port DD on the oil circuit board (13). The rodless chamber of the fourth back pressure cylinder (32) is connected to the oil port DC on the oil circuit board (13) through the fourth hydraulic control check valve (45), the control oil port of the fourth hydraulic control check valve (45) is connected to the oil port CD on the oil circuit board (13), and the rod chamber of the fourth back pressure cylinder (32) is connected to the oil port DD on the oil circuit board (13). The rodless chamber of the expansion cylinder (49) is connected to the oil port EC on the oil circuit board (13), and the rod chamber is connected to the oil port ED on the oil circuit board (13).

2. The hydraulic control system for a fracture breaker according to claim 1, characterized in that: An oil supply check valve (7) is connected between the oil outlet of the oil pump unit (6) and the output port GP of the oil supply device (01). An overflow valve (8) is provided between the oil outlet of the oil pump unit (6) and the oil tank (1). A first pressure gauge (11) is connected to the output port GP of the oil supply device (01), and a second pressure gauge (12) is connected to the oil outlet of the oil pump unit (6).

3. The hydraulic control system for a fracture breaker according to claim 1, characterized in that: The output port GP of the oil supply device (01) is connected to a safety valve group (10), and the safety valve group (10) is located between the oil supply accumulator (9) and the output port GP. The drain port of the safety valve group (10) is connected to the oil tank (1).

4. The hydraulic control system for a fracture breaker according to claim 1, characterized in that: A first one-way throttle valve (17) is connected between port BA of the first three-position four-way solenoid valve (16) and port BC of the oil circuit block, and between port BB and port BD. A second one-way throttle valve (20) is connected between port DA of the second three-position four-way solenoid valve (19) and port DC of the oil circuit block, and between port DB and port DD. A third one-way throttle valve (23) is connected between port EA of the third three-position four-way solenoid valve (21) and port EC of the oil circuit block, and between port EB and port ED. A one-way pressure reducing valve (22) is provided between port EB and the corresponding third one-way throttle valve (23).

5. The hydraulic control system for a fracture breaker according to claim 1, characterized in that: A first safety valve (34) is connected in parallel with the first hydraulic check valve (33) between the rodless chamber of the first back pressure cylinder (29) and the oil port BC of the oil circuit board (13). A second safety valve (38) is connected in parallel with the second hydraulic check valve (37) between the rodless chamber of the second back pressure cylinder (30) and the oil port BC of the oil circuit board (13). A third safety valve (42) is connected in parallel with the third hydraulic check valve (41) between the rodless chamber of the third back pressure cylinder (31) and the oil port DC of the oil circuit board (13). A fourth safety valve (46) is connected in parallel with the fourth hydraulic check valve (45) between the rodless chamber of the fourth back pressure cylinder (32) and the oil port DC of the oil circuit board (13).

6. The hydraulic control system for a fracture breaker according to claim 1, characterized in that: The oil tank (1) is equipped with a level gauge (2), a level controller (3), an oil temperature controller (4), and an air filter (5).

7. A hydraulic control method for a fracture breaker, characterized in that: The control system described in any one of claims 1-6 specifically includes the following steps: S1. The oil supply device (01) builds pressure; the oil pump unit (6) is started, and the oil pump unit (6) inputs the oil in the oil tank (1) into the oil supply accumulator (9) so that the oil pump unit (6) reaches the set pressure. S2. Provide back pressure to the workpiece; the electromagnet YVBB of the first three-position four-way solenoid valve (16) and the electromagnet YVDB of the second three-position four-way solenoid valve (19) are simultaneously energized, the oil port BP of the first three-way four-position solenoid valve is connected to the oil port BA, the oil port BT is connected to the oil port BB, the oil port DP of the second three-position four-way solenoid valve (19) is connected to the oil port DA, and the oil port DT is connected to the oil port DB; the oil in the oil tank (1) passes through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, and the main pressure reducing valve (14). The oil ports BP and BA of the first three-way four-position solenoid valve and the oil port BC of the oil circuit block enter the rodless chamber of the first back pressure cylinder (29) through the first hydraulic check valve (33), enter the rodless chamber of the second back pressure cylinder (30) through the second hydraulic check valve (37), and enter the rodless chamber of the second back pressure cylinder (30) through the oil ports DP and DA of the second three-way four-position solenoid valve and the oil port DC of the oil circuit block, enter the rodless chamber of the third back pressure cylinder (31) through the third hydraulic check valve (41), and enter the rodless chamber of the fourth back pressure cylinder (32) through the fourth hydraulic check valve (45). The oil in the rod chamber of the first back pressure cylinder (29) and the oil in the rod chamber of the second back pressure cylinder (30) return to the oil tank (1) through the oil port BD of the oil circuit block, the oil port BB and oil port BT of the first three-position four-way solenoid valve (16), the oil port KT of the oil circuit block, and the return oil port GT of the oil supply device (01). The oil in the rod chamber of the third back pressure cylinder (31) and the oil in the rod chamber of the fourth back pressure cylinder (32) return to the oil tank (1) through the oil port DD of the oil circuit block, the oil port DB and oil port DT of the second three-position four-way solenoid valve (19), the oil port KT of the oil circuit block, and the return oil port GT of the oil supply device (01). When the pressure in the rodless chambers of the first back pressure cylinder (29), the second back pressure cylinder (30), the third back pressure cylinder (31), and the fourth back pressure cylinder (32) reaches the pressure set by the first pressure controller (36), the second pressure controller (40), the third pressure controller (44), and the fourth pressure controller (48), respectively, the electromagnet YVBB of the first three-position four-way solenoid valve (16) and the electromagnet YVDB of the second three-position four-way solenoid valve (19) are simultaneously de-energized and reset. The first back pressure accumulator (35), the second back pressure accumulator (39), the third back pressure accumulator (43), and the fourth back pressure accumulator (47) maintain pressure, thereby providing back pressure to the workpiece. S3, the expansion cylinder (49) slowly descends; the electromagnet YVEB of the third three-position four-way solenoid valve (21) is energized, its oil port EP is connected to oil port EA, and its oil port ET is connected to oil port EB. The oil in the oil tank (1) enters the rodless chamber of the expansion cylinder (49) through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil port EP, oil port EA of the third three-position four-way solenoid valve (21), and the oil port EC of the oil circuit block; the oil in the rod chamber of the expansion cylinder (49) returns to the oil tank (1) through the oil port ED of the oil circuit block, the oil port EB, oil port ET of the third three-position four-way solenoid valve (21), the oil port KT of the oil circuit block, and the return port GT of the oil supply device (01). The piston rod of the expansion cylinder (49) slowly extends. S4, Rapidly break the workpiece; The electromagnet YVFB of the fourth three-position four-way solenoid valve (28) is energized, its oil port FP is connected to oil port FA, and its oil port FT is connected to oil port FB. The oil in the oil tank (1) passes through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil port FP and oil port FA of the fourth three-position four-way solenoid valve (28) and enters the oil port KC of the first damping two-way valve (24) and the oil port MC of the third damping two-way valve (26). The first damping two-way valve (24) and the third damping two-way valve (26) are in the closed state. The oil port KA and oil port KB of the first damping two-way valve (24) are disconnected, and the oil port MA and oil port MB of the third damping two-way valve (26) are disconnected. The oil from port LC of the second damping two-way valve (25) and port NC of the fourth damping two-way valve (27) returns to the oil tank (1) through port FB, port FT of the fourth three-position four-way solenoid valve (28), port KL of the oil circuit block, and port GL of the oil supply device (01). The second damping two-way valve (25) and the fourth damping two-way valve (27) are opened. Port LA of the second damping two-way valve (25) is connected to port LB, and port NA and port NB of the fourth damping two-way valve (27) are connected. The oil in the oil tank (1) enters the rodless chamber of the expansion cylinder (49) through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil ports LB, LA and EC of the second damping two-way valve (25), and the oil port EC of the oil circuit block. The oil in the rod chamber of the expansion cylinder (49) returns to the oil tank (1) through the oil port ED of the oil circuit block, the oil ports NA, NB and KT of the fourth damping two-way valve (27), and the drain port GT of the oil supply device (01). The piston rod of the expansion cylinder (49) extends rapidly to achieve the expansion and breakage of the workpiece. The first back pressure accumulator (35), the second back pressure accumulator (39), the third back pressure accumulator (43) and the fourth back pressure accumulator (47) absorb the hydraulic shock during the expansion and breakage. S5, the expansion cylinder (49) returns quickly; the electromagnet YVFA of the fourth three-position four-way solenoid valve (28) is energized, its oil port FP is connected to oil port FB, and its oil port FT is connected to oil port FA. The oil in the oil tank (1) passes through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil port FP and oil port FB of the fourth three-position four-way solenoid valve (28) and enters the oil port LC of the second damping two-way valve (25) and the oil port NC of the fourth damping two-way valve (27). The second damping two-way valve (25) and the fourth damping two-way valve (27) are in the closed state. The oil port LA and oil port LB of the second damping two-way valve (25) are disconnected, and the oil port NA and oil port NB of the fourth damping two-way valve (27) are disconnected. The oil from port KC of the first damping two-way valve (24) and port MC of the third damping two-way valve (26) returns to the oil tank (1) through port FA, port FT of the fourth three-position four-way solenoid valve (28), port KL of the oil circuit block, and the drain port GL of the oil supply device (01). The first damping two-way valve (24) and the third damping two-way valve (26) are opened. Port KA of the first damping two-way valve (24) is connected to port KB, and port MA and port MB of the third damping two-way valve (26) are connected. The oil in the oil tank (1) enters the rod chamber of the expansion cylinder (49) through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil port MB, the oil port MA of the third damping two-way valve (26), and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder (49) returns to the oil tank (1) through the oil port EC of the oil circuit block, the oil port KA, the oil port KB of the first damping two-way valve (24), the oil port KT of the oil circuit block, and the drain port GT of the oil supply device (01). The piston rod of the expansion cylinder (49) retracts rapidly. S6, the expansion cylinder (49) slowly returns; the electromagnet YVEA of the third three-position four-way solenoid valve (21) is energized, its oil port EP is connected to oil port EB, and its oil port ET is connected to oil port EA. The oil in the oil tank (1) enters the rod chamber of the expansion cylinder (49) through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the oil port EP, the oil port EB of the third three-position four-way solenoid valve (21), and the oil port ED of the oil circuit block. The oil in the rodless chamber of the expansion cylinder (49) returns to the oil tank (1) through the oil port EC of the oil circuit block, the oil port EA, the oil port ET of the third three-position four-way solenoid valve (21), the oil port KT of the oil circuit block, and the drain port GT of the oil supply device (01). The piston rod of the expansion cylinder (49) slowly retracts. S7, back pressure cylinder depressurization; the electromagnet YVAA of the first two-position four-way solenoid valve (15) and the electromagnet YVCA of the second two-position four-way solenoid valve (18) are energized at the same time, the first three-position four-way solenoid valve (16) and the second three-position four-way solenoid valve (19) are in the middle position, the oil port AP and oil port AB of the first two-position four-way solenoid valve (15) are connected, the oil port AT and oil port AA are connected, the oil port CP and oil port CB of the second two-position four-way solenoid valve (18) are connected, and the oil port CT and oil port CA are connected. The oil in the oil tank (1) passes through the output port GP of the oil pump unit (6), the oil supply device (01), the oil port KP of the oil circuit block, the main pressure reducing valve (14), the oil ports AP and AB of the first two-position four-way solenoid valve (15), and the oil port AD of the oil circuit block, and enters the control ports of the first hydraulic control check valve (33) and the second hydraulic control check valve (37). The first hydraulic control check valve (33) and the second hydraulic control check valve (37) are open; the first back pressure cylinder (29) The oil in the rodless chamber is output through the first hydraulic control check valve (33), and the oil in the rodless chamber of the second back pressure cylinder (30) is output through the second hydraulic control check valve (37). The oil returns to the oil tank (1) through the oil port BC of the oil circuit block, the oil port BA and oil port BT of the first three-position four-way solenoid valve (16), the oil port KT of the oil circuit block, and the oil drain port GT of the oil supply device (01), thereby realizing the depressurization of the first back pressure cylinder (29) and the second back pressure cylinder (30). The oil in the oil tank (1) passes through the output port GP of the oil pump unit (6), the oil supply device (01), the oil port KP of the oil circuit block, the main pressure reducing valve (14), the oil port CP, the oil port CB of the second two-position four-way solenoid valve (18), and the oil port CD of the oil circuit block, and enters the control ports of the third hydraulic control check valve (41) and the fourth hydraulic control check valve (45). The third hydraulic control check valve (41) and the fourth hydraulic control check valve (45) are open; the third back pressure cylinder (31) The oil in the rodless chamber is output through the third hydraulic control check valve (41), and the oil in the rodless chamber of the fourth back pressure cylinder (32) is output through the fourth hydraulic control check valve (45). The oil returns to the oil tank (1) through the oil port DC of the oil circuit block, the oil port DA and oil port DT of the second three-position four-way solenoid valve (19), the oil port KT of the oil circuit block, and the oil drain port GT of the oil supply device (01), thereby realizing the pressure relief of the third back pressure cylinder (31) and the fourth back pressure cylinder (32). S8, back pressure cylinder reset; the solenoid YVAA of the first two-position four-way solenoid valve (15), the solenoid YVBA of the first three-position four-way solenoid valve (16), the solenoid YVCA of the second two-position four-way solenoid valve (18), and the solenoid YVDA of the second three-position four-way solenoid valve (19) are simultaneously energized, the oil port AP of the first two-position four-way solenoid valve (15) is connected to the oil port AB, the oil port AT is connected to the oil port AA, the oil port BP of the first three-position four-way solenoid valve (16) is connected to the oil port BB, the oil port BT is connected to the oil port BA, the oil port CP of the second two-position four-way solenoid valve (18) is connected to the oil port CB, the oil port CT is connected to the oil port CA, the oil port DP of the second three-position four-way solenoid valve (19) is connected to the oil port DB, the oil port DT is connected to the oil port DA, the first hydraulic control check valve (33), the second hydraulic control check valve (37), the third hydraulic control check valve (41) and the fourth hydraulic control check valve (45) are opened; The oil in the oil tank (1) passes through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the main pressure reducing valve (14), the oil ports BP, BB and BD of the first three-position four-way solenoid valve (16), and the oil port BD of the oil circuit block, respectively entering the rod chamber of the first back pressure cylinder (29) and the rod chamber of the second back pressure cylinder (30). The oil in the rodless chamber of the first back pressure cylinder (29) is output through the first hydraulic control check valve (33), and the oil in the rodless chamber of the second back pressure cylinder (30) is output through the second hydraulic control check valve (37). The oil returns to the oil tank (1) through the oil port BC of the oil circuit block, the oil ports BA and BT of the first three-position four-way solenoid valve (16), the oil port KT of the oil circuit block, and the drain port GT of the oil supply device (01). The first back pressure cylinder (29) and the fourth back pressure cylinder (32) are reset. The oil in the oil tank (1) passes through the oil pump unit (6), the output port GP of the oil supply device (01), the oil port KP of the oil circuit block, the main pressure reducing valve (14), the oil ports DP, DB and DD of the second three-position four-way solenoid valve (19), and the oil port DD of the oil circuit block, respectively entering the rod chamber of the third back pressure cylinder (31) and the rod chamber of the fourth back pressure cylinder (32). The oil in the rodless chamber of the third back pressure cylinder (31) is output through the third hydraulic control check valve (41), and the oil in the rodless chamber of the fourth back pressure cylinder (32) is output through the fourth hydraulic control check valve (45). The oil returns to the oil tank (1) through the oil port DC of the oil circuit block, the oil ports DA and DT of the second three-position four-way solenoid valve (19), the oil port KT of the oil circuit block, and the drain port GT of the oil supply device (01). The third back pressure cylinder (31) and the fourth back pressure cylinder (32) are reset.

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