Ultra-high pressure hydraulic system and control method for gear press fitting process

Abstract

The present invention discloses an ultra-high pressure hydraulic system and control method for a gear press fitting process, comprising a servo motor, an ultra-high pressure plunger pump, an oil tank, a safety valve, a first electromagnetic stop valve, a proportional relief valve, a first pressure sensor, a second electromagnetic stop valve, a first throttle damper, a second throttle damper, a third throttle damper, a third electromagnetic stop valve, a fourth electromagnetic stop valve, an electromagnetic pressure holding valve, and a second pressure sensor. By controlling the overflow pressure of the proportional relief valve, the linear pressure loading and pressure relief of the tensioning tool at 0-70 MPa is achieved, the on-off of each throttle damper is controlled, and the pump outlet flow rate is controlled by adjusting the motor speed, the pressure difference on each throttle damper is changed, and the linear pressure loading and pressure relief of the tensioning tool at 70-200 MPa is achieved. The present invention can be used in an ultra-high pressure hydraulic system of 200 MPa to achieve segmented adjustment of the loading pressure, and can control the amplitude and slope of the pressure increase or decrease of the tensioning pressure at 0-200 MPa.

Description

Technical Field

[0001] The present invention relates to the field of ultra-high pressure hydraulic transmission, and in particular to an ultra-high pressure hydraulic system and a control method for a gear press-fitting process. Background Art

[0002] The gear press-fitting process requires ultra-high-pressure hydraulic oil to enter the tensioner, causing it to expand or release pressure. To ensure control accuracy during the press-fitting process, it is necessary to be able to adjust and control the pressure increase and release values ​​of the tensioner, as well as the time of pressure change. A proportional relief valve can control the pressure of the ultra-high-pressure system, but the maximum pressure in the tensioner can reach 200 MPa. Currently, the maximum adjustable pressure of the proportional relief valve is only 70 MPa, making it difficult to linearly increase or decrease pressures above 70 MPa. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides an ultra-high pressure hydraulic system and control method for a gear press fitting process, which can achieve linear adjustment of the pressurization / decompression of the tensioning tooling pressure within the range of 0-200MPa.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] An ultra-high-pressure hydraulic system for a gear press-fitting process includes a servo motor, an ultra-high-pressure plunger pump, an oil tank, a safety valve, a first electromagnetic stop valve, a proportional relief valve, a first pressure sensor, a second electromagnetic stop valve, a first throttle damper, a second throttle damper, a third throttle damper, a third electromagnetic stop valve, a fourth electromagnetic stop valve, an electromagnetic pressure-maintaining valve, and a second pressure sensor;

[0006] The servo motor drives the ultra-high pressure plunger pump to rotate and discharge hydraulic oil;

[0007] The inlet of the safety valve is connected to the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the oil tank; the inlet of the first electromagnetic shut-off valve is connected to the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the proportional relief valve; the outlet of the proportional relief valve is connected to the oil tank;

[0008] The first pressure sensor is connected to the outlet oil circuit of the ultra-high-pressure plunger pump to feedback the pressure of the ultra-high-pressure hydraulic system; the inlet of the second electromagnetic stop valve is connected to the outlet oil circuit of the ultra-high-pressure plunger pump, and the outlet is connected to the inlet of the first throttle damper; the first throttle damper, the second throttle damper, and the third throttle damper are connected in series in sequence; the inlet and outlet of the third electromagnetic stop valve are respectively connected to the inlet and outlet of the second throttle damper, and the inlet and outlet of the fourth electromagnetic stop valve are respectively connected to the inlet and outlet of the third throttle damper; the outlet of the fourth electromagnetic stop valve and the outlet of the third throttle damper are both connected to the oil tank;

[0009] The two oil ports of the electromagnetic pressure maintaining valve are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump and the oil inlet of the tightening tooling of the gear press-fitting process;

[0010] The second pressure sensor is connected to the oil inlet circuit of the tensioning fixture and is used to feed back the oil pressure in the tensioning fixture.

[0011] Furthermore, the first electromagnetic stop valve is a normally open structure, and the second electromagnetic stop valve, the third electromagnetic stop valve, the fourth electromagnetic stop valve and the electromagnetic pressure maintaining valve are all normally closed structures.

[0012] Furthermore, the ultra-high pressure plunger pump is a radial plunger pump, and the maximum output pressure is greater than 200 MPa.

[0013] Furthermore, the safety valve is a manual overflow valve structure.

[0014] Furthermore, the valve core of the electromagnetic pressure-maintaining valve is a cone valve structure, which can lock the high-pressure side pressure in the power-off state.

[0015] Furthermore, the proportional relief valve is proportionally adjustable within a pressure range of 0-70 MPa.

[0016] Furthermore, the first throttling damping, the second throttling damping and the third throttling damping are all fixed opening damping.

[0017] Furthermore, the sum of the maximum pressure differences generated by the first throttling damping, the second throttling damping and the third throttling damping is greater than the maximum pressure required by the gear press-fitting process.

[0018] A control method for an ultra-high pressure hydraulic system used in a gear press-fitting process, wherein the pressure control in the tensioning tool is divided into three stages: 0-70 MPa, 70-140 MPa, and 140-200 MPa, as follows:

[0019] The 0-70MPa pressurization control process is as follows: the first electromagnetic stop valve and the electromagnetic pressure-maintaining valve are controlled to be in the on state, and the second electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the off state; the servo motor is controlled to rotate to drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil is quickly filled into the tensioning tooling through the electromagnetic pressure-maintaining valve; after the oil filling is completed, the tensioning tooling becomes a closed cavity, and the tensioning pressure is consistent with the ultra-high-pressure system pressure; the current of the proportional relief valve is adjusted to increase to control the increase in the ultra-high-pressure system pressure; the slope of the current increase of the proportional relief valve is adjusted to control the pressure rise curve of the internal oil of the tensioning tooling;

[0020] The pressurization control process of 70-140Mpa is as follows: the first electromagnetic stop valve and the third electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve, the fourth electromagnetic stop valve, and the electromagnetic pressure maintaining valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the second electromagnetic stop valve, the first throttle damper, the second throttle damper, and the fourth electromagnetic stop valve; a pressure difference is generated due to the oil flowing through the two throttle dampers, thereby establishing the outlet pressure and tightening pressure of the ultra-high pressure pump; the speed of the servo motor is controlled to increase, the flow rate of oil discharged by the ultra-high pressure plunger pump increases, the pressure difference generated on the two throttle dampers increases, and the tightening pressure increases accordingly; the slope of the servo motor speed increase is adjusted to control the pressure rise curve of the internal oil of the tightening tooling;

[0021] The pressurization control process of 140-200Mpa is as follows: the first electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve and the electromagnetic pressure-maintaining valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the third throttle damper; the outlet pressure and the tightening pressure of the ultra-high-pressure pump are established by the pressure difference generated by the oil flowing through the three throttle dampers; the speed of the servo motor is controlled to increase, the flow rate of oil discharged by the ultra-high-pressure plunger pump increases, the pressure difference generated on the three throttle dampers increases, and the tightening pressure increases accordingly; the slope of the servo motor speed increase is adjusted to control the pressure rise curve of the oil inside the tightening tooling;

[0022] During the entire pressurization control process, the tightening pressure is accurately controlled through the pressure feedback of the second pressure sensor.

[0023] Furthermore, the pressure reduction control in the tensioning tool is divided into three stages: 200-140 MPa, 140-70 MPa and 70-0 MPa, as follows:

[0024] The pressure reduction control process of 200-140 MPa is as follows: the first electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve and the electromagnetic pressure maintaining valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the third throttle damper; the speed of the servo motor is controlled to decrease, the flow rate of oil discharged by the ultra-high pressure plunger pump is reduced, the pressure difference generated on the three throttle dampers is reduced, and the tightening pressure is reduced accordingly; the slope of the servo motor speed reduction is adjusted to control the pressure drop curve of the oil inside the tightening tooling;

[0025] The 140-70 MPa pressure reduction control process is as follows: the first and third electromagnetic stop valves are controlled to remain in the disconnected state, and the second, fourth, and electromagnetic pressure-maintaining valves are controlled to remain in the connected state; the servo motor is controlled to rotate and drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the fourth electromagnetic stop valve; the speed of the servo motor is controlled to decrease, the flow rate of oil discharged by the ultra-high-pressure plunger pump decreases, the pressure difference generated on the two throttle dampers decreases, and the tensioning pressure decreases accordingly; the slope of the servo motor speed decreases is adjusted to control the pressure drop curve of the oil inside the tensioning tooling;

[0026] The 70-0Mpa pressure reduction control process is as follows: control the first electromagnetic stop valve and the electromagnetic pressure maintaining valve to be in the on state, and the second electromagnetic stop valve, the third electromagnetic stop valve and the fourth electromagnetic stop valve to be in the off state; control the servo motor to drive the ultra-high pressure plunger pump to discharge hydraulic oil; adjust the current of the proportional relief valve to reduce, and control the pressure drop of the ultra-high pressure hydraulic system; adjust the slope of the current reduction of the proportional relief valve to control the pressure drop curve of the oil inside the tightening tooling.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The present invention can be used in 200MPa-level ultra-high-pressure hydraulic systems to achieve segmented adjustment of loading pressure.

[0029] 2. The present invention can control the pressure increase amplitude and pressure increase slope of the tightening pressure in the range of 0-200 MPa.

[0030] 3. The present invention can control the pressure reduction amplitude and pressure reduction curve of the tensioning pressure in the range of 200-0 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the principle of an ultra-high pressure hydraulic system for a gear press-fitting process according to an embodiment of the present invention.

[0032] Figure 2 This is the oil circuit diagram for controlling the internal pressure of the tensioning tool of the present invention, which is 0-70MPa pressurization / 70-0MPa decompression.

[0033] Figure 3 This is the state switching oil circuit diagram when the tightening pressure of the present invention rises to 70MPa or drops to 140MPa.

[0034] Figure 4 This is the oil circuit diagram for controlling the internal pressure of the tensioning tool of the present invention to be 70-140MPa pressurized / 140-70MPa decompressed.

[0035] Figure 5This is the oil circuit diagram for switching when the tightening pressure rises to 140 MPa.

[0036] Figure 6 This is the oil circuit diagram for controlling the internal pressure of the tensioning tool of the present invention to be 140-200 MPa pressurization / 200-140 MPa decompression.

[0037] Figure 7 This is the oil circuit diagram for switching the state when the tightening pressure drops to 70 MPa.

[0038] In the figure, 1 is the servo motor, 2 is the ultra-high pressure plunger pump, 3 is the oil tank, 4 is the safety valve, 5 is the first electromagnetic stop valve, 6 is the proportional relief valve, 7 is the first pressure sensor, 8 is the second electromagnetic stop valve, 9 is the first throttling damper, 10 is the second throttling damper, 11 is the third throttling damper, 12 is the third electromagnetic stop valve, 13 is the fourth electromagnetic stop valve, 14 is the electromagnetic pressure maintaining valve, 15 is the second pressure sensor, and 16 is the tensioning tooling. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more apparent. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] like Figure 1 As shown, the ultra-high pressure hydraulic system for the gear pressing process of this embodiment includes a servo motor 1, an ultra-high pressure plunger pump 2, an oil tank 3, a safety valve 4, a first electromagnetic stop valve 5, a proportional overflow valve 6, a first pressure sensor 7, a second electromagnetic stop valve 8, a first throttle damper 9, a second throttle damper 10, a third throttle damper 11, a third electromagnetic stop valve 12, a fourth electromagnetic stop valve 13, an electromagnetic pressure holding valve 14 and a second pressure sensor 15.

[0041] Servo motor 1 drives ultra-high-pressure plunger pump 2 to rotate and discharge hydraulic oil. Ultra-high-pressure plunger pump 2 is a radial piston pump with a maximum output pressure greater than 200 MPa. The output flow rate of ultra-high-pressure plunger pump 2 can be controlled by adjusting the speed of servo motor 1. Ultra-high-pressure plunger pump 2 draws oil from oil tank 3, and all return oil in the system returns to oil tank 3.

[0042] The inlet of safety valve 4 is connected to the outlet of ultra-high-pressure plunger pump 2. It is a manual relief valve with a pressure setting of 210 MPa, which limits the maximum pressure of the ultra-high-pressure system. The inlet of first solenoid shut-off valve 5 is connected to the outlet oil circuit of ultra-high-pressure plunger pump 2 and is a normally open structure. Proportional relief valve 6 is proportionally adjustable within the pressure range of 0-70 MPa. The inlet of proportional relief valve 6 is connected to the outlet of first solenoid shut-off valve 5, and the outlet of proportional relief valve 6 is connected to oil tank 3.

[0043] The first pressure sensor 7 is connected to the outlet oil line of the ultra-high pressure plunger pump 2 and is used to feedback the ultra-high pressure system pressure.

[0044] The inlet of the second electromagnetic stop valve 8 is connected to the outlet oil circuit of the ultra-high pressure plunger pump 2 and is a normally closed structure. The first throttle damper 9 is a fixed opening damper, and its inlet is connected to the outlet of the second electromagnetic stop valve 8. The second throttle damper 10 is a fixed opening damper, and its inlet is connected to the outlet of the first throttle damper 9. The third throttle damper 11 is a fixed opening damper, and its inlet is connected to the outlet of the second throttle damper 10, and its outlet is connected to the oil tank 3. The inlet and outlet of the third electromagnetic stop valve 12 are respectively connected to the inlet and outlet of the second throttle damper 10 and are a normally closed structure. The inlet and outlet of the fourth electromagnetic stop valve 13 are respectively connected to the inlet and outlet of the third throttle damper 11 and are a normally closed structure.

[0045] The two oil ports of the electromagnetic pressure maintaining valve 14 are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump 2 and the oil inlet of the tightening tooling 16. It is a normally-off structure, and the valve core is a cone valve structure, which can lock the high-pressure side pressure in the power-off state.

[0046] The second pressure sensor 15 is connected to the oil inlet circuit of the tensioning fixture 16 to provide feedback on the oil pressure in the tensioning fixture.

[0047] The cavity of the tensioning fixture 16 is a closed cavity, and its oil inlet and oil outlet are the same oil port.

[0048] When the servo motor 1 rotates at the highest speed, the pressure difference formed by the hydraulic oil discharged by the ultra-high pressure plunger pump 2 through a single throttle damper can reach more than 70MPa. When the servo motor 1 rotates at a low speed, the pressure difference formed by the hydraulic oil discharged by the ultra-high pressure plunger pump 2 through a single throttle damper can be controlled within 30MPa. The number of throttle dampers is not limited to three given in this embodiment. The maximum pressure difference that can be generated by the number of throttle dampers and a single throttle damper is P max The product must be greater than the maximum pressure required by the gear tooling.

[0049] The pressure control process of the tensioning tooling with a pressure of 0-200MPa is as follows:

[0050] like Figure 2As shown, the process for controlling the pressure within the tensioner from 0 to 70 MPa is as follows: the first, second, third, and fourth solenoid shut-off valves 5, 8, 12, and 13 are all de-energized, while the solenoid pressure-maintaining valve 14 is energized. The servo motor 1 rotates at high speed, driving the ultra-high-pressure plunger pump 2 to discharge hydraulic oil. This oil rapidly fills the tensioner 16 through the solenoid pressure-maintaining valve 14. Once filled, the tensioner 16 becomes a closed chamber, and the tensioning pressure remains consistent with the system pressure. The rise in ultra-high-pressure system pressure is controlled by increasing the current flowing through the proportional relief valve 6. Adjusting the slope of the current increase modulates the pressure rise curve within the tensioner 16. Pressure feedback from the second pressure sensor 15 allows for precise control of the tensioning pressure. When the pressure feedback from the second pressure sensor 15 reaches 70 MPa, pressure control is complete.

[0051] like Figure 3 As shown, when the tightening pressure rises to 70 MPa, the state switches to the following: the electromagnetic pressure-maintaining valve 14 loses power, the current of the proportional relief valve 6 is adjusted to 0, and the outlet pressure of the ultra-high-pressure plunger pump drops to 0 MPa. Due to the pressure-maintaining effect of the electromagnetic pressure-maintaining valve 14, the pressure in the tightening tooling 16 remains at 70 MPa. The servo motor 1 decelerates to the minimum speed. After the second electromagnetic stop valve 8 and the fourth electromagnetic stop valve 13 are energized, the first electromagnetic stop valve 5 is energized, the overflow circuit is closed, and the pump outlet oil returns through the second electromagnetic stop valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic stop valve 13. At this time, the pump outlet flow rate is small, and the pressure difference generated on the two throttle dampers is insufficient to make the pump outlet oil circuit pressure reach 70 MPa. The speed of the servo motor 1 is controlled to increase. When the feedback pressure of the first pressure sensor 7 reaches 70 MPa, the pressurization switching state is completed.

[0052] like Figure 4 As shown, the pressure control process for the tensioner 16 to maintain a pressure between 70 and 140 MPa is as follows: the first solenoid shut-off valve 5, the second solenoid shut-off valve 8, the fourth solenoid shut-off valve 13, and the solenoid pressure-maintaining valve 14 are energized, while the third solenoid shut-off valve 12 remains de-energized. The pump outlet oil returns through the second solenoid shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth solenoid shut-off valve 13. This increases the speed of the servo motor 1, increasing the oil flow rate discharged by the ultra-high-pressure plunger pump 2. This increases the pressure differential across the two throttle dampers 9 and 10, and consequently, the tensioning pressure. Adjusting the slope of the speed increase controls the pressure rise curve of the oil inside the tensioner 16. Pressure feedback from the second pressure sensor 15 allows for precise control of the tensioning pressure. When the pressure feedback from the second pressure sensor 15 reaches 140 MPa, the pressure control is complete.

[0053] like Figure 5As shown, when the tightening pressure rises to 140 MPa, the state switches to: the electromagnetic pressure-holding valve 14 loses power, the servo motor 1 decelerates to the minimum speed, the outlet pressure of the ultra-high-pressure plunger pump is lower than 140 MPa, and due to the pressure-holding effect of the electromagnetic pressure-holding valve 14, the pressure in the tightening tooling 16 is still maintained at 140 MPa, the second electromagnetic stop valve 8 is energized, and the third and fourth electromagnetic stop valves 12 and 13 are de-energized. The oil at the pump outlet returns through the second electromagnetic stop valve 8, the first throttle damper 9, the second throttle damper 10, and the third throttle damper 11. At this time, the pump outlet flow rate is small, and the pressure difference generated on the three throttle dampers is insufficient to make the pump outlet oil circuit pressure reach 140 MPa. The speed of the servo motor 1 is controlled to increase. When the feedback pressure of the first pressure sensor 7 reaches 140 MPa, the pressurization switching state is completed.

[0054] like Figure 6 As shown, the pressure control process for increasing the tensioner's internal pressure to 140-200 MPa is as follows: the first solenoid shut-off valve 5, the second solenoid shut-off valve 8, and the solenoid pressure-maintaining valve 14 are energized, while the third and fourth solenoid shut-off valves 12 and 13 remain de-energized. The pump outlet oil returns through the second solenoid shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the third throttle damper 11. This increases the speed of the servo motor 1, increasing the oil flow rate discharged by the ultra-high-pressure plunger pump 2. This increases the pressure differential across the three throttle dampers, and consequently, the tensioning pressure. Adjusting the speed ramp rate controls the pressure rise curve of the oil within the tensioner 16. Pressure feedback from the second pressure sensor 15 allows for precise control of the tensioning pressure. When the pressure feedback from the second pressure sensor 15 reaches 200 MPa, pressure control is complete.

[0055] The pressure control process of the tensioning tooling with a pressure of 200-0MPa is as follows:

[0056] like Figure 6 As shown, the pressure reduction control process for the tensioner fixture (200-140 MPa) is as follows: the first solenoid shut-off valve 5, the second solenoid shut-off valve 8, and the solenoid pressure-maintaining valve 14 are energized, while the third solenoid shut-off valve 12 and the fourth solenoid shut-off valve 13 remain de-energized. The speed of the servo motor 1 is controlled to decrease, reducing the oil flow rate discharged by the ultra-high-pressure plunger pump 2. This reduces the pressure differential across the three throttling dampers, and consequently, the tensioning pressure. Adjusting the slope of the speed reduction controls the pressure drop curve of the oil within the tensioner fixture 16. Pressure reduction control is complete when the pressure feedback from the second pressure sensor 15 drops to 140 MPa.

[0057] like Figure 3As shown, when the tightening pressure drops to 140 MPa, the state switches to: the electromagnetic pressure-maintaining valve 14 and the third electromagnetic stop valve 12 lose power, the second electromagnetic stop valve 8 and the fourth electromagnetic stop valve 13 are energized, and the oil at the pump outlet returns through the second electromagnetic stop valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic stop valve 13. The outlet pressure of the ultra-high-pressure plunger pump drops below 140 MPa. Due to the pressure-maintaining effect of the electromagnetic pressure-maintaining valve 14, the pressure in the tightening tooling 16 remains at 140 MPa, and the speed of the servo motor 1 is controlled to increase. When the feedback pressure of the first pressure sensor 7 reaches 140 MPa, the pressure reduction switching state is completed.

[0058] like Figure 4 As shown, the pressure reduction control process for the tensioner fixture (140-70 MPa) is as follows: the second solenoid shut-off valve 8, the fourth solenoid shut-off valve 13, and the solenoid pressure-maintaining valve 14 are energized, while the third solenoid shut-off valve 12 remains de-energized. The pump outlet oil returns through the second solenoid shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth solenoid shut-off valve 13, controlling the servo motor 1 to reduce its speed. This reduces the oil flow rate discharged by the ultra-high-pressure plunger pump 2, the pressure differential across the two throttle dampers, and consequently, the tensioning pressure. Adjusting the slope of the speed reduction controls the pressure drop curve of the oil inside the tensioner fixture 16. Pressure reduction control is complete when the pressure feedback from the second pressure sensor 15 drops to 70 MPa.

[0059] like Figure 7 As shown, when the tightening pressure drops to 70 MPa, the state switches to: the electromagnetic pressure maintaining valve 14, the second electromagnetic stop valve 8, the third electromagnetic stop valve 12, and the fourth electromagnetic stop valve 13 lose power, the first electromagnetic stop valve 5 is energized, and the pump outlet oil returns through the first electromagnetic stop valve 8 and the proportional relief valve 6. The outlet pressure of the ultra-high pressure plunger pump drops to 0 MPa. Due to the pressure maintaining effect of the electromagnetic pressure maintaining valve 14, the pressure in the tightening tooling 16 is still maintained at 70 MPa, and the current of the proportional relief valve 6 is controlled to increase. When the feedback pressure of the first pressure sensor 7 reaches 70 MPa, the pressure reduction switching state is completed.

[0060] like Figure 2 As shown, the pressure reduction control process for the tensioner 16 from 70 MPa to 0 MPa is as follows: the first, second, third, and fourth solenoid shut-off valves 5, 8, 12, and 13 remain de-energized, while the solenoid pressure-maintaining valve 14 remains energized. The system pressure drop is controlled by reducing the current flowing through the proportional relief valve 6. Adjusting the slope of the current reduction modifies the pressure drop curve of the oil within the tensioner 16. Pressure reduction control is completed when the pressure feedback from the second pressure sensor 15 drops to 0 MPa.

[0061] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art will still be able to modify the technical solutions described in the foregoing examples or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. An ultra-high pressure hydraulic system for gear press-fitting process, characterized in that: It includes a servo motor, an ultra-high pressure plunger pump, an oil tank, a safety valve, a first electromagnetic stop valve, a proportional relief valve, a first pressure sensor, a second electromagnetic stop valve, a first throttle damper, a second throttle damper, a third throttle damper, a third electromagnetic stop valve, a fourth electromagnetic stop valve, an electromagnetic pressure maintaining valve and a second pressure sensor; The servo motor drives the ultra-high pressure plunger pump to rotate and discharge hydraulic oil; The inlet of the safety valve is connected to the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the oil tank; the inlet of the first electromagnetic shut-off valve is connected to the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the proportional relief valve; the outlet of the proportional relief valve is connected to the oil tank; The first pressure sensor is connected to the outlet oil circuit of the ultra-high-pressure plunger pump to feedback the pressure of the ultra-high-pressure hydraulic system; the inlet of the second electromagnetic stop valve is connected to the outlet oil circuit of the ultra-high-pressure plunger pump, and the outlet is connected to the inlet of the first throttle damper; the first throttle damper, the second throttle damper, and the third throttle damper are connected in series in sequence; the inlet and outlet of the third electromagnetic stop valve are respectively connected to the inlet and outlet of the second throttle damper, and the inlet and outlet of the fourth electromagnetic stop valve are respectively connected to the inlet and outlet of the third throttle damper; the outlet of the fourth electromagnetic stop valve and the outlet of the third throttle damper are both connected to the oil tank; The two oil ports of the electromagnetic pressure maintaining valve are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump and the oil inlet of the tightening tooling of the gear press-fitting process; The second pressure sensor is connected to the oil inlet circuit of the tensioning fixture and is used to feed back the oil pressure in the tensioning fixture.

2. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The first electromagnetic stop valve is a normally open structure, and the second electromagnetic stop valve, the third electromagnetic stop valve, the fourth electromagnetic stop valve and the electromagnetic pressure maintaining valve are all normally closed structures.

3. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The ultra-high pressure plunger pump is a radial plunger pump with a maximum output pressure greater than 200 MPa.

4. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The safety valve is a manual overflow valve structure.

5. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The valve core of the electromagnetic pressure-maintaining valve is a cone valve structure, which can lock the high-pressure side pressure in the power-off state.

6. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The proportional relief valve is proportionally adjustable within a pressure range of 0-70 MPa.

7. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 1, characterized in that: The first throttling damping, the second throttling damping and the third throttling damping are all fixed opening damping.

8. The ultra-high pressure hydraulic system for gear press-fitting process according to claim 7, characterized in that: The sum of the maximum pressure differences generated by the first throttling damping, the second throttling damping and the third throttling damping is greater than the maximum pressure required by the gear press-fitting process.

9. A control method for an ultra-high pressure hydraulic system for a gear press-fitting process according to claim 1, characterized in that: The pressure control in the tensioning tool is divided into three stages: 0-70MPa, 70-140Mpa, and 140-200Mpa, as follows: The 0-70MPa pressurization control process is as follows: the first electromagnetic stop valve and the electromagnetic pressure-maintaining valve are controlled to be in the on state, and the second electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the off state; the servo motor is controlled to rotate to drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil is quickly filled into the tensioning tooling through the electromagnetic pressure-maintaining valve; after the oil filling is completed, the tensioning tooling becomes a closed cavity, and the tensioning pressure is consistent with the ultra-high-pressure system pressure; the current of the proportional relief valve is adjusted to increase to control the increase in the ultra-high-pressure system pressure; the slope of the current increase of the proportional relief valve is adjusted to control the pressure rise curve of the internal oil of the tensioning tooling; The pressurization control process of 70-140Mpa is as follows: the first electromagnetic stop valve and the third electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve, the fourth electromagnetic stop valve, and the electromagnetic pressure maintaining valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the second electromagnetic stop valve, the first throttle damper, the second throttle damper, and the fourth electromagnetic stop valve; a pressure difference is generated due to the oil flowing through the two throttle dampers, thereby establishing the outlet pressure and tightening pressure of the ultra-high pressure pump; the speed of the servo motor is controlled to increase, the flow rate of oil discharged by the ultra-high pressure plunger pump increases, the pressure difference generated on the two throttle dampers increases, and the tightening pressure increases accordingly; the slope of the servo motor speed increase is adjusted to control the pressure rise curve of the internal oil of the tightening tooling; The pressurization control process of 140-200 MPa is as follows: the first electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve and the electromagnetic pressure holding valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the third throttle damper; The outlet pressure and tensioning pressure of the ultra-high-pressure pump are established by the pressure difference generated by the oil flowing through the three throttling dampers; the speed of the servo motor is controlled to increase, the flow rate of oil discharged by the ultra-high-pressure plunger pump increases, the pressure difference generated on the three throttling dampers increases, and the tensioning pressure increases accordingly; the slope of the servo motor speed increase is adjusted to control the pressure rise curve of the oil inside the tensioning tool; During the entire pressurization control process, the tightening pressure is accurately controlled through the pressure feedback of the second pressure sensor.

10. The control method of the ultra-high pressure hydraulic system for the gear press-fitting process according to claim 9, characterized in that: The pressure reduction control in the tensioning tool is divided into three stages: 200-140Mpa, 140-70Mpa and 70-0MPa, as follows: The pressure reduction control process of 200-140 MPa is as follows: the first electromagnetic stop valve, the third electromagnetic stop valve, and the fourth electromagnetic stop valve are controlled to be in the disconnected state, and the second electromagnetic stop valve and the electromagnetic pressure maintaining valve are controlled to be in the connected state; the servo motor is controlled to rotate and drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the third throttle damper; the speed of the servo motor is controlled to decrease, the flow rate of oil discharged by the ultra-high pressure plunger pump is reduced, the pressure difference generated on the three throttle dampers is reduced, and the tightening pressure is reduced accordingly; the slope of the servo motor speed reduction is adjusted to control the pressure drop curve of the oil inside the tightening tooling; The 140-70 MPa pressure reduction control process is as follows: the first and third electromagnetic stop valves are controlled to remain in the disconnected state, and the second, fourth, and electromagnetic pressure-maintaining valves are controlled to remain in the connected state; the servo motor is controlled to rotate and drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the fourth electromagnetic stop valve; the speed of the servo motor is controlled to decrease, the flow rate of oil discharged by the ultra-high-pressure plunger pump decreases, the pressure difference generated on the two throttle dampers decreases, and the tensioning pressure decreases accordingly; the slope of the servo motor speed decreases is adjusted to control the pressure drop curve of the oil inside the tensioning tooling; The 70-0Mpa pressure reduction control process is as follows: control the first electromagnetic stop valve and the electromagnetic pressure maintaining valve to be in the on state, and the second electromagnetic stop valve, the third electromagnetic stop valve and the fourth electromagnetic stop valve to be in the off state; control the servo motor to drive the ultra-high pressure plunger pump to discharge hydraulic oil; adjust the current of the proportional relief valve to reduce, and control the pressure drop of the ultra-high pressure hydraulic system; adjust the slope of the current reduction of the proportional relief valve to control the pressure drop curve of the oil inside the tightening tooling.

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