Hydraulic cylinder proportional control loop and hydraulic machine

Abstract

The invention relates to the technical field of hydraulic power, and particularly discloses a hydraulic cylinder proportional control loop and a hydraulic machine. The hydraulic cylinder proportional control loop comprises a liquid filling oil tank, a hydraulic cylinder, an oil pipe set and a control valve set. The oil pipe set is provided with a first connector, a second connector, a main oil return opening, a main pump oil opening, a main control oil opening and a main oil drainage opening. The control valve group comprises an oil return cartridge valve, a first cartridge valve group, a second cartridge valve group and a proportional valve; the main oil return port is in on-off connection with the first interface through the oil return cartridge valve; the master pump oil port and the master oil return port are communicated with a port A of the proportional valve in a switching mode through the first cartridge valve set, and the first connector and the second connector are communicated with a port B of the proportional valve in a switching mode through the second cartridge valve set. By the adoption of the hydraulic circuit, the stretching speed of the main cylinder during stretching can be effectively controlled, the working precision of the main cylinder during pressurization, pressure maintaining and pressure relief can be controlled, and it is guaranteed that the hydraulic circuit can effectively meet the working requirement of the hydraulic machine.

Description

Technical Field

[0001] This invention relates to the field of hydraulic power technology, and in particular to a proportional control circuit for a hydraulic cylinder and a hydraulic press. Background Technology

[0002] Existing hydraulic presses typically employ a valve control system that includes a three-way proportional valve and a two-way proportional valve to achieve speed control. The three-way proportional valve controls the descent and ascent speed of the moving beam, while the two-way proportional valve controls the pressurization and pressure holding speed of the moving beam.

[0003] However, in actual applications, the above valve control systems experience significant impacts when the main cylinder extends or retracts and when it depressurizes, while their accuracy during pressurization is low, easily exceeding the set pressure, thus failing to meet the actual usage requirements of the hydraulic press. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a hydraulic cylinder proportional control circuit and a hydraulic press, which can effectively control the extension and retraction speed of the main cylinder during extension and retraction, as well as the working accuracy of the main cylinder during pressurization, pressure holding, and pressure release, ensuring that the hydraulic circuit can effectively meet the working requirements of the hydraulic press.

[0005] To solve the above-mentioned technical problems, the first aspect of the present invention provides a proportional control circuit for a hydraulic cylinder, including a filling oil tank, a hydraulic cylinder, an oil pipe assembly, and a control valve assembly. The filling oil tank is connected to the hydraulic cylinder through a directional control valve assembly. The oil pipe assembly forms a first interface, a second interface, a main return port, a main pump port, a main control port, and a main drain port. The first interface is connected to the rod chamber of the hydraulic cylinder, and the second interface is connected to the rodless chamber of the hydraulic cylinder. The directional control valve assembly is used to switch the direction of the oil circuit between the filling oil tank and the hydraulic cylinder. The control valve group includes a return oil cartridge valve, a first cartridge valve group, a second cartridge valve group, and a proportional valve. The main return oil port is connected to the first interface through the return oil cartridge valve. The main pump port and the main return port are switched to be connected to the A port of the proportional valve through the first cartridge valve group, and the first interface and the second interface are switched to be connected to the B port of the proportional valve through the second cartridge valve group. The main control port is connected to the control ports of the first cartridge valve group and the second cartridge valve group, respectively, and the control ports of the first cartridge valve group and the second cartridge valve group are connected to the main drain port. The proportional valve is used to proportionally control the flow rate of the oil circuit between the first cartridge valve group and the second cartridge valve group.

[0006] As an improvement to the above solution, the first cartridge valve group includes a second cartridge valve and a third cartridge valve. The A port of the second cartridge valve is connected to the main return port, the A port of the third cartridge valve is connected to the main pump port, and the B ports of the second cartridge valve and the third cartridge valve are connected to the proportional valve switching connection. The main control port is switched to be connected to the X port of the second cartridge valve and the X port of the third cartridge valve; The X port of the second cartridge valve and the X port of the third cartridge valve are switched to be connected to the main drain port.

[0007] As an improvement to the above solution, a first directional valve is arranged between the X port of the second cartridge valve and the X port of the third cartridge valve, and the first directional valve has at least a first working position and a second working position. When the first station is powered on, the X port of the second cartridge valve is connected to the main drain port, and the X port of the third cartridge valve is connected to the main control port. When the second station is powered on, the X port of the second cartridge valve is connected to the main control oil port, and the X port of the third cartridge valve is connected to the main drain port.

[0008] As an improvement to the above scheme, the second cartridge valve group includes a fourth cartridge valve and a fifth cartridge valve. The B port of the fourth cartridge valve is connected to the first interface, the B port of the fifth cartridge valve is connected to the second interface, and the A ports of the fourth cartridge valve and the A ports of the fifth cartridge valve are switched to be connected to the B port of the proportional valve. The main control port is switched to be connected to the X port of the fourth cartridge valve and the X port of the fifth cartridge valve; The X port of the fourth cartridge valve and the X port of the fifth cartridge valve are switched to be connected to the main drain port.

[0009] As an improvement to the above scheme, a second directional valve is arranged between the X port of the fourth cartridge valve and the X port of the fifth cartridge valve, and the second directional valve has at least a third position and a fourth position. When the third station is energized, the X port of the fourth cartridge valve is connected to the main control oil port, and the X port of the fifth cartridge valve is connected to the main drain port. When the fourth station is energized, the X port of the fourth cartridge valve is connected to the main drain port, and the X port of the fifth cartridge valve is connected to the main control port.

[0010] As an improvement to the above solution, the oil inlet of the second directional valve is provided with a first shuttle valve, the first inlet of the first shuttle valve is connected to the first interface, and the second inlet of the first shuttle valve is connected to the main control oil port.

[0011] As an improvement to the above solution, a pressure sensor is provided between the B port of the fifth cartridge valve and the second interface, and a displacement sensor is provided in the rod chamber of the hydraulic cylinder.

[0012] As an improvement to the above solution, the A port of the return oil cartridge valve is connected to the main return oil port, and the B port of the return oil cartridge valve is connected to the first interface. The X port of the return oil cartridge valve is equipped with a third directional valve. The third directional valve has at least a fifth position and a sixth position. When the sixth position is energized, the X port of the return oil cartridge valve is connected to the main control oil port. When the fifth position is energized, the X port of the return oil cartridge valve is connected to the main drain port.

[0013] As an improvement to the above solution, the return oil cartridge valve is connected in parallel with a safety valve. The inlet of the safety valve is connected to the rod chamber of the hydraulic cylinder, and the outlet of the safety valve is connected to the main return oil port.

[0014] As an improvement to the above solution, the directional control valve group includes a hydraulic filling valve and a fourth directional valve. The hydraulic filling valve has a first oil port and a second oil port. The first oil port is connected to the filling oil tank, and the second oil port is connected to the rodless chamber of the hydraulic cylinder. The fourth directional valve is arranged between the X port of the hydraulic filling valve and the main control oil port. The fourth directional valve has at least a seventh position and an eighth position. When the eighth station is powered on, the X port of the hydraulic filling valve is disconnected from the main control oil port; When the seventh station is powered on, the X port of the hydraulic filling valve is connected to the main control oil port.

[0015] Accordingly, a second aspect of the present invention provides a hydraulic press comprising the hydraulic cylinder proportional control circuit described in any of the preceding claims.

[0016] Implementing this invention has the following beneficial effects: The hydraulic cylinder proportional control circuit of the present invention, by switching the connection state between the main pump oil port, the main return oil port and port A of the proportional valve, and by switching the connection state between the first interface, the second interface and port B of the proportional valve, can form a main cylinder extension circuit, a main cylinder retraction circuit, a main cylinder pressurization and pressure holding circuit, and a main cylinder pressure relief circuit as required. By using the proportional valve to control the flow and pressure of the above circuits, it is possible to control the extension and retraction speed of the main cylinder, as well as the working accuracy of the main cylinder pressurization, pressure holding and pressure relief, so as to ensure that the hydraulic circuit can effectively meet the working requirements of the hydraulic press. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the piping structure of the proportional control circuit of the hydraulic cylinder in this invention; Figure 2 This is a schematic diagram of the piping structure of the first cartridge valve assembly in this invention; Figure 3 This is a schematic diagram of the piping structure of the second cartridge valve assembly in this invention; Figure 4 This is a schematic diagram of the pipeline structure of the return oil cartridge valve in this invention; Figure 5 This is a schematic diagram of the piping structure of the main cylinder extension circuit in this invention; Figure 6 This is a schematic diagram of the piping structure of the main cylinder retraction circuit in this invention; Figure 7 This is a schematic diagram of the piping structure of the main cylinder pressurization circuit and the main cylinder pressure holding circuit in this invention; Figure 8 This is a schematic diagram of the pipeline structure of the master cylinder pressure relief circuit in this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0019] The first aspect of this invention provides a proportional control circuit for a hydraulic cylinder, such as... Figures 1 to 4 As shown, the proportional control circuit of the hydraulic cylinder includes a filling oil tank 1, a hydraulic cylinder 2, an oil pipe assembly, and a control valve assembly. The filling oil tank 1 and the hydraulic cylinder 2 are connected through the directional control valve assembly. The oil pipe assembly forms a first interface A1, a second interface A2, a main return port T1, a main pump port P1, a main control port X1, and a main drain port L1. The first interface A1 is connected to the rod chamber of the hydraulic cylinder 2, and the second interface A2 is connected to the rodless chamber of the hydraulic cylinder 2. The directional control valve assembly is used to switch the direction of the oil circuit between the filling oil tank and the hydraulic cylinder.

[0020] The control valve group includes a return oil cartridge valve 3, a first cartridge valve group 4, a second cartridge valve group 5, and a proportional valve 6. The main return oil port T1 is connected to the first interface A1 through the return oil cartridge valve 3. That is, when the return oil cartridge valve 3 is open, the main return oil port T1 is connected to the first interface A1, and when the return oil cartridge valve 3 is closed, the main return oil port T1 is disconnected from the first interface A1.

[0021] The main pump port P1 and the main return port T1 are switched to be connected to port A of the proportional valve 6 through the first cartridge valve group 4. The first port A1 and the second port A2 are switched to be connected to port B of the proportional valve 6 through the second cartridge valve group 5. That is, when the hydraulic cylinder proportional control circuit is working, port A of the proportional valve 6 can be selectively connected to either the main pump port P1 or the main return port T1 through the first cartridge valve group 4, and port B of the proportional valve can be selectively connected to either the first port A1 or the second port A2 through the second cartridge valve group 5.

[0022] The main control port X1 is connected to the control ports of the first cartridge valve group 4 and the second cartridge valve group 5 respectively, and the control ports of the first cartridge valve group 4 and the second cartridge valve group 5 are connected to the main drain port L1 respectively. The proportional valve 6 is used to proportionally control the flow rate of the oil circuit between the first cartridge valve group 4 and the second cartridge valve group 5.

[0023] In this embodiment, the hydraulic cylinder proportional control circuit, by switching the connection state between the main pump port P1, the main return port T1 and the A port of the proportional valve 6, and by switching the connection state between the first interface A1, the second interface A2 and the B port of the proportional valve 6, can form a main cylinder extension circuit, a main cylinder retraction circuit, a main cylinder pressurization and pressure holding circuit, and a main cylinder pressure relief circuit 14 as required. By using the proportional valve 6 to control the flow and pressure of the above circuits, it is possible to control the extension and retraction speed of the main cylinder, as well as the working accuracy of the main cylinder during pressurization, pressure holding and pressure relief, ensuring that the hydraulic circuit can effectively meet the working requirements of the hydraulic press.

[0024] Specifically, when the master cylinder needs to extend rapidly, the second cartridge valve group 5, under the action of control oil, connects the first port A1 to the B port of the proportional valve 6. The first cartridge valve group 4, under the action of control oil, connects the A port of the proportional valve 6 to the total return port T1, and the directional control valve group opens the oil circuit from the filling oil tank 1 to the hydraulic cylinder 2. Thus, an extension return oil pipeline 112 is formed between the rod chamber of the hydraulic cylinder 2, the first port A1, the proportional valve 6, and the total return port T1. Simultaneously, an extension filling oil pipeline 111 is formed between the filling oil tank 1 and the rodless chamber of the hydraulic cylinder 2. Therefore, the extension filling oil pipeline 111 and the extension return oil pipeline 112 form the master cylinder extension circuit. The proportional valve 6 controls the flow rate of the extension return oil pipeline 112 between the first cartridge valve group 4 and the second cartridge valve group 5, correspondingly controlling the extension speed of the master cylinder, shortening the extension time of the master cylinder, and reducing operational shock.

[0025] When rapid retraction of the master cylinder is required, the directional control valve assembly opens the oil passage from hydraulic cylinder 2 to the filling oil tank 1. Furthermore, under the action of control oil, the first cartridge valve assembly 4 connects the master pump port P1 to port A of the proportional valve 6, and the second cartridge valve assembly 5 connects port B of the proportional valve 6 to the first interface A1. This forms a retraction filling oil passage 121 between the master pump port P1, the proportional valve 6, the first interface A1, and the rod chamber of hydraulic cylinder 2. Simultaneously, a retraction return oil passage 122 is formed between the rodless chamber of hydraulic cylinder 2 and the filling oil tank 1, thus creating a master cylinder retraction circuit using the retraction filling oil passage 121 and the retraction return oil passage 122. The proportional valve 6 controls the flow rate of the retraction filling oil passage 121 between the second cartridge valve assembly 5 and the first cartridge valve assembly 4, correspondingly controlling the retraction speed of the master cylinder, shortening the master cylinder retraction time, and reducing operational shock.

[0026] When proportional pressurization of the master cylinder is required, the directional control valve group opens the oil circuit from hydraulic cylinder 2 to filling oil tank 1, preventing the hydraulic oil in filling oil tank 1 from flowing to hydraulic cylinder 2. Furthermore, under the action of control oil, the first cartridge valve group 4 connects the master pump port P1 to port A of the proportional valve 6, and the second cartridge valve group 5 connects port B of the proportional valve 6 to the second interface A2 under the action of control oil. Simultaneously, the first interface A1 is connected to the main return port T1 through the return cartridge valve 3. Furthermore, a pressurized oil filling pipeline 131 is formed between the main pump port P1, the proportional valve 6, the second port A2, and the rodless chamber of the hydraulic cylinder 2. A pressurized oil return pipeline 132 is formed between the rod chamber of the hydraulic cylinder 2, the first port A1, the return oil cartridge valve 3, and the main return oil port T1. Thus, a main cylinder pressurization circuit is formed between the pressurized oil filling pipeline 131 and the pressurized oil return pipeline 132. The proportional valve 6 controls the flow and pressure of the pressurized oil filling pipeline 131 between the second cartridge valve group 5 and the first cartridge valve group 4 to achieve closed-loop pressure control during main cylinder pressurization, ensuring the main cylinder pressurization accuracy and pressurization speed.

[0027] When the pressure of the master cylinder reaches the set holding pressure, the master cylinder pressurization circuit also becomes the master cylinder holding pressure circuit. At this time, the actual pressure of the master cylinder can be maintained near the set holding pressure by adjusting the valve core opening of the proportional valve 6, thereby ensuring the holding pressure accuracy of the master cylinder by using the proportional valve 6.

[0028] When proportional pressure relief of the main cylinder is required, the main control port X1 is connected to the hydraulic filling valve 9, keeping the hydraulic filling valve 9 open in reverse. Simultaneously, under the action of control oil, the second cartridge valve group 5 connects the second interface A2 to the B port of the proportional valve 6, while the first cartridge valve group 4 connects the A port of the proportional valve 6 to the main return port T1 under the action of control oil. This forms a main cylinder pressure relief circuit 14 between the rodless chamber of the hydraulic cylinder 2, the second interface A2, the proportional valve 6, and the main return port T1. The proportional valve 6 controls the flow and pressure of the main cylinder pressure relief circuit 14 between the first cartridge valve group 4 and the second cartridge valve group 5, achieving closed-loop pressure control during main cylinder pressure relief and ensuring the accuracy and speed of main cylinder pressure relief.

[0029] It should be noted that the hydraulic oil in the filling tank 1 is low-pressure hydraulic oil, which is injected into the rodless chamber of hydraulic cylinder 2 at a high flow rate, thereby propelling hydraulic cylinder 2 to extend rapidly. The hydraulic oil pumped into the rod or rodless chamber by the master pump port P1 is high-pressure hydraulic oil, so that when high-pressure oil is injected into the rod chamber, it can drive hydraulic cylinder 2 to retract rapidly, and when high-pressure oil is injected into the rodless chamber, it can achieve pressurization and pressure holding operations for hydraulic cylinder 2.

[0030] It should also be noted that the proportional valve 6 is preferably a two-way cartridge-type high-frequency response proportional valve, which includes a main-stage cartridge valve and a pilot-stage proportional regulating valve. The main-stage cartridge valve has two working ports and one control port. The two working ports are designated as ports A and B, and the control port is designated as port X. When the amplifier board of the pilot-stage proportional regulating valve is energized, it outputs a pilot control pressure proportional to the electrical signal and applies it to the control port of the main-stage cartridge valve, correspondingly controlling the valve core opening of the main-stage cartridge valve. Thus, by controlling the electrical signal input to the pilot-stage proportional regulating valve, the flow and pressure between ports A and B of the main-stage cartridge valve can be proportionally controlled, thereby achieving proportional control of the flow and pressure in the hydraulic cylinder proportional control circuit. The port naming of the two-way cartridge-type high-frequency response proportional valve follows the ISO international standard.

[0031] As a preferred embodiment, such as Figure 1 and Figure 2 As shown, the first cartridge valve group 4 includes a second cartridge valve 41 and a third cartridge valve 42. Port A of the second cartridge valve 41 is connected to the main return port T1, and port A of the third cartridge valve 42 is connected to the main pump port P1. Ports B of the second cartridge valve 41 and the third cartridge valve 42 are switched to be connected to the proportional valve 6. That is, when the hydraulic cylinder proportional control circuit is working, the proportional valve 6 can be selectively connected to either port B of the second cartridge valve 41 or port B of the third cartridge valve 42.

[0032] The main control port X1 is switched to be connected to the X port of the second cartridge valve 41 and the X port of the third cartridge valve 42; the X ports of the second cartridge valve 41 and the X ports of the third cartridge valve 42 are switched to be connected to the main drain port L1. That is, when the hydraulic cylinder proportional control circuit is working, the main control port X1 can be selectively connected to one of the X ports of the second cartridge valve 41 and the X port of the third cartridge valve 42; the main drain port L1 can be selectively connected to one of the X ports of the second cartridge valve 41 and the X port of the third cartridge valve 42.

[0033] Therefore, the second cartridge valve 41 can independently control the connection state between the main return port T1 and the proportional valve 6, while the third cartridge valve 42 independently controls the connection state between the main pump port P1 and the proportional valve 6. When the second cartridge valve 41 is open, the third cartridge valve 42 is closed, and when the third cartridge valve 42 is open, the second cartridge valve 41 is closed. By switching the opening or closing of the second cartridge valve 41 and the third cartridge valve 42, the accuracy of the switching connection between the main pump port P1, the main return port T1 and the A port of the proportional valve 6 can be effectively guaranteed.

[0034] Furthermore, such as Figure 2 As shown, a first directional valve 43 is arranged between the X port of the second cartridge valve 41 and the X port of the third cartridge valve 42. The first directional valve 43 has at least a first position and a second position. In this embodiment, the first directional valve is preferably a three-position four-way solenoid directional valve. In addition to forming the first position and the second position, it also forms a neutral position. When the three-position four-way solenoid directional valve is not working, the valve core is located in the neutral position, and the first position is the left position of the three-position four-way solenoid directional valve, and the second position is the right position of the three-position four-way solenoid directional valve.

[0035] When the first directional valve 43 is energized at its first position, the X port of the second cartridge valve 41 is connected to the main drain port L1, and the X port of the third cartridge valve 42 is connected to the main control port X1. Correspondingly, opening the second cartridge valve 41 simultaneously closes the third cartridge valve 42, thus connecting the A port of the proportional valve 6 to the main return port T1 while disconnecting the main pump port P1 from the A port of the proportional valve 6. When the first directional valve 43 is energized at its second position, the X port of the second cartridge valve 41 is connected to the main control port X1, and the X port of the third cartridge valve 42 is connected to the main drain port L1. Correspondingly, opening the third cartridge valve 42 simultaneously closes the second cartridge valve 41, thus connecting the main pump port P1 to the A port of the proportional valve 6 while disconnecting the A port of the proportional valve 6 from the main return port T1. Furthermore, by switching the power to the first and second positions of the first directional valve 43, the second cartridge valve 41 and the third cartridge valve 42 can be switched to open and close, effectively simplifying the switching operation and improving convenience and accuracy.

[0036] As an optional embodiment, such as Figure 1 and Figure 3As shown, the second cartridge valve group 5 includes a fourth cartridge valve 51 and a fifth cartridge valve 52. The B port of the fourth cartridge valve 51 is connected to the first interface A1, and the B port of the fifth cartridge valve 52 is connected to the second interface A2. The A ports of the fourth cartridge valve 51 and the fifth cartridge valve 52 are switched to be connected to the B port of the proportional valve. That is, when the hydraulic cylinder proportional control circuit is working, the B port of the proportional valve 6 can be selectively connected to either the A port of the fourth cartridge valve 51 or the A port of the fifth cartridge valve 52.

[0037] The main control port X1 is switched to be connected to the X port of the fourth cartridge valve 51 and the X port of the fifth cartridge valve 52; the X ports of the fourth cartridge valve 51 and the X ports of the fifth cartridge valve 52 are switched to be connected to the main drain port L1. That is, when the hydraulic cylinder proportional control circuit is working, the main control port X1 can be selectively connected to one of the X ports of the fourth cartridge valve 51 and the X port of the fifth cartridge valve 52; the main drain port L1 can be selectively connected to one of the X ports of the fourth cartridge valve 51 and the X port of the fifth cartridge valve 52.

[0038] Therefore, the fourth cartridge valve 51 can independently control the connection state between the proportional valve 6 and the first interface A1, while the fifth cartridge valve 52 independently controls the connection state between the second interface A2 and the proportional valve 6. When the fourth cartridge valve 51 is open, the fifth cartridge valve 52 is closed, and when the fifth cartridge valve 52 is open, the fourth cartridge valve 51 is closed. By switching the fourth cartridge valve 51 and the fifth cartridge valve 52 open or close, the accuracy of switching the connection between the first interface A1, the second interface A2 and port B of the proportional valve 6 can be effectively guaranteed.

[0039] Furthermore, such as Figure 3 As shown, a second directional valve 53 is arranged between the X port of the fourth cartridge valve 51 and the X port of the fifth cartridge valve 52. The second directional valve 53 has at least a third position and a fourth position. In this embodiment, the second directional valve is preferably a three-position four-way solenoid directional valve. In addition to forming the third position and the fourth position, it also forms a neutral position. When the three-position four-way solenoid directional valve is not working, the valve core is located in the neutral position, and the third position is the left position of the three-position four-way solenoid directional valve, and the fourth position is the right position of the three-position four-way solenoid directional valve.

[0040] When the second directional valve 53 is energized at its third position, the X port of the fourth cartridge valve 51 is connected to the main control oil port X1, and the X port of the fifth cartridge valve 52 is connected to the main drain port L1. Correspondingly, opening the fourth cartridge valve 51 simultaneously closes the fifth cartridge valve 52, thus connecting the B port of the proportional valve 6 to the first interface A1 while disconnecting the second interface A2 from the B port of the proportional valve 6. When the second directional valve 53 is energized at its fourth position, the X port of the fourth cartridge valve 51 is connected to the main drain port L1, and the X port of the fifth cartridge valve 52 is connected to the main control oil port X1. Correspondingly, opening the fifth cartridge valve 52 simultaneously closes the fourth cartridge valve 51, thus connecting the second interface A2 to the B port of the proportional valve 6 while disconnecting the B port of the proportional valve 6 from the first interface A1. Furthermore, by switching the power to the third and fourth positions of the second directional valve 53, the fourth cartridge valve 51 and the fifth cartridge valve 52 can be switched to open and close, effectively simplifying the switching operation and improving convenience and accuracy.

[0041] Therefore, in this embodiment, by adjusting the energization state of the first directional valve 43 and the second directional valve 53, the hydraulic cylinder proportional control circuit can be configured as required to form a main cylinder extension circuit, a main cylinder retraction circuit, a main cylinder pressurization and pressure holding circuit, and a main cylinder pressure relief circuit 14. This ensures that the hydraulic circuit effectively meets the working requirements of the hydraulic press while simplifying the convenience and accuracy of circuit switching.

[0042] Among them, the first operating condition of the hydraulic circuit, such as Figure 5 As shown, by simultaneously energizing the left position of the first directional valve 43 and the right position of the second directional valve 53, the X ports of the second cartridge valve 41 and the fourth cartridge valve 51 can be connected to the main drain port L1, and the X ports of the third cartridge valve 42 and the fifth cartridge valve 52 can be connected to the main control port X1. This opens the second cartridge valve 41, closes the third cartridge valve 42, opens the fourth cartridge valve 51, and closes the fifth cartridge valve 52. This forms an extended return oil pipeline 112 between the rod chamber of the hydraulic cylinder 2, the first interface A1, the fourth cartridge valve 51, the proportional valve 6, the second cartridge valve 41, and the main return oil port T1. Under the regulation of the flow rate of the pipeline between the fourth cartridge valve 51 and the second cartridge valve 41 by the proportional valve 6, and with the cooperation of the extended filling oil pipeline 111 formed by the forward opening of the hydraulic filling valve, the main cylinder can be rapidly extended.

[0043] As the second operating condition of the hydraulic circuit, such as Figure 6As shown, by simultaneously energizing the right positions of the first directional valve 43 and the second directional valve 53, the X ports of the third cartridge valve 42 and the fourth cartridge valve 51 can be connected to the main drain port L1, and the X ports of the second cartridge valve 41 and the fifth cartridge valve 52 can be connected to the main control port X1. This closes the second cartridge valve 41, opens the third cartridge valve 42, opens the fourth cartridge valve 51, and closes the fifth cartridge valve 52. This forms a retraction filling pipeline 121 between the main pump port P1, the third cartridge valve 42, the proportional valve 6, the fourth cartridge valve 51, the first interface A1, and the rod chamber of the hydraulic cylinder 2. Under the regulation of the flow rate in the pipeline between the third cartridge valve 52 and the fourth cartridge valve 51 by the proportional valve 6, and with the cooperation of the retraction return pipeline 122 formed by the reverse opening of the hydraulic filling valve 9, the main cylinder can retract rapidly.

[0044] As the third operating condition of the hydraulic circuit, such as Figure 7 As shown, by simultaneously energizing the right position of the first directional valve 43 and the left position of the second directional valve 53, the X ports of the third cartridge valve 42 and the fifth cartridge valve 52 can be connected to the main drain port L1, and the X ports of the second cartridge valve 41 and the fourth cartridge valve 51 can be connected to the main control port X1. This closes the second cartridge valve 41, opens the third cartridge valve 42, closes the fourth cartridge valve 51, and opens the fifth cartridge valve 52. This forms a pressurized oil filling pipeline 131 between the main pump port P1, the third cartridge valve 42, the proportional valve 6, the fifth cartridge valve 52, the second port A2, and the rodless chamber of the hydraulic cylinder 2. Under the regulation of the flow rate of the pipeline between the third cartridge valve 41 and the fifth cartridge valve 52 by the proportional valve 6, and with the cooperation of the pressurized return oil pipeline 132 formed by the opening of the return oil cartridge valve 3, the main cylinder is proportionally pressurized. When the oil pressure in the main cylinder reaches the set holding pressure, the proportional valve 6 and the pressurized oil filling line 131 are used to achieve proportional holding pressure in the main cylinder.

[0045] As the fourth operating condition of the hydraulic circuit, such as Figure 8 As shown, by simultaneously energizing the left positions of the first directional valve 43 and the second directional valve 53, the X ports of the second cartridge valve 41 and the fifth cartridge valve 52 can be connected to the main drain port L1, and the X ports of the third cartridge valve 42 and the fourth cartridge valve 51 can be connected to the main control port X1. This opens the second cartridge valve 41, closes the third cartridge valve 42, closes the fourth cartridge valve 51, and opens the fifth cartridge valve 52. This forms a main cylinder pressure relief circuit 14 between the rodless chamber of the hydraulic cylinder 2, the second port A2, the fifth cartridge valve 52, the proportional valve 6, the second cartridge valve 41, and the main return port T1. Under the regulation of the flow rate in the pipeline between the fifth cartridge valve 52 and the second cartridge valve 41 by the proportional valve 6, the main cylinder achieves proportional pressure relief.

[0046] It should also be noted that the cartridge valve is preferably a two-way cartridge valve. The valve body has two working ports and one control port. The two working ports are designated as Port A and Port B, and the control port is designated as Port X. When Port X is pressurized, the cartridge valve is closed regardless of whether Port A or Port B is pressurized. When Port X is depressurized, and Port A is pressurized to the point that the pressure at Port A is greater than the pressure at Port B, the cartridge valve is open, and hydraulic oil can flow from Port A to Port B. When Port X is depressurized, and Port B is pressurized to the point that the pressure at Port B is greater than the pressure at Port A, the cartridge valve is open, and hydraulic oil can flow from Port B to Port A. The port naming of the two-way cartridge valve follows the ISO international standard.

[0047] As an optional embodiment, such as Figure 1 and Figure 3 As shown, the inlet of the second directional valve 53 is equipped with a first shuttle valve 54. The first inlet of the first shuttle valve 54 is connected to the first interface A1, and the second inlet of the first shuttle valve 54 is connected to the main control port X1. Therefore, when the hydraulic cylinder 2 switches from extension / retraction to pressurized extension, if the hydraulic oil pressure in the rod chamber of the hydraulic cylinder 2 is greater than the control oil pressure of the main control port X1, the hydraulic oil pressure in the rod chamber of the hydraulic cylinder 2 can be used to flow through the shuttle valve and the second directional valve 53, and into the X port of the fourth cartridge valve 51 to control the fourth cartridge valve 51 to close. This consumes the oil pressure in the rod chamber of the hydraulic cylinder 2, ensuring that the pressure in the rod chamber is always below the safety threshold, thus guaranteeing the safety performance of the hydraulic cylinder 2 during pressurization and pressure holding.

[0048] As an optional embodiment, such as Figure 1 and Figure 3 As shown, a pressure sensor 7 is installed between port B of the fifth cartridge valve 52 and the second interface A2. When the hydraulic cylinder 2 is pressurized, the pressure sensor 7 detects the hydraulic oil pressure flowing into the rodless chamber of the hydraulic cylinder 2 through the fifth cartridge valve 52 and the second interface A2. This allows for real-time comparison between the pressure set by the hydraulic cylinder 2 and the detection value of the pressure sensor 7, and real-time adjustment of the pilot control pressure of the proportional valve 6. This achieves closed-loop pressure control in the hydraulic circuit and further ensures the pressure holding accuracy of the main cylinder.

[0049] Hydraulic cylinder 2 is equipped with displacement sensor 8. When hydraulic cylinder 2 extends and retracts rapidly, displacement sensor 8 is used to detect the real-time extension and retraction displacement of hydraulic cylinder 2 so as to adjust the pilot control pressure of proportional valve 6 in real time, realize the closed-loop control of flow rate in hydraulic circuit, and further ensure that the extension and retraction time of main rod is reduced and the impact of main cylinder extension and retraction is reduced.

[0050] Furthermore, by utilizing the feedback control of pressure sensor 7 and displacement sensor 8, in conjunction with proportional valve 6, pressure closed-loop control and position closed-loop control are achieved. This ensures that proportional valve 6 controls the flow and pressure of the hydraulic cylinder proportional control circuit, further guaranteeing the working accuracy of the extension and retraction speed of the main cylinder during extension and retraction, as well as the working accuracy of the main cylinder during pressurization, pressure holding, and pressure release.

[0051] In this embodiment, as Figure 1 and Figure 4 As shown, port A of the return oil cartridge valve 3 is connected to the main return oil port T1, and port B of the return oil cartridge valve 3 is connected to the first interface A1. By controlling the opening and closing state of the return oil cartridge valve 3, the main return oil port T1 is connected to the rod chamber of the hydraulic cylinder 2. This allows the return oil cartridge valve 3 to provide an additional return oil line to the hydraulic circuit when the main cylinder is pressurized and maintained, thus ensuring the pressurization and pressure maintenance accuracy of the main cylinder.

[0052] Specifically, such as Figure 4 As shown, a third directional valve 31 is arranged at the X port of the return oil cartridge valve 3. The third directional valve 31 has at least a fifth position and a sixth position. In this embodiment, the third directional valve 31 is preferably a two-position four-way solenoid directional valve. The fifth position is the left position of the two-position four-way solenoid directional valve, and the sixth position is the right position of the two-position four-way solenoid directional valve. When the sixth position of the third directional valve 31 is energized, the X port of the return oil cartridge valve 3 is connected to the main control oil port X1. When the fifth position of the third directional valve 31 is energized, the X port of the return oil cartridge valve 3 is connected to the main drain port L1. That is, when the main cylinder needs to be proportionally pressurized and maintained, the fifth position of the third directional valve 31 can be energized to form a pressurized return oil pipeline 132 between the rod chamber of the hydraulic cylinder 2, the first interface A1, the return oil cartridge valve 3, and the main return oil port T1, thereby cooperating with the pressurized filling oil pipeline 131 to complete the proportional pressurization of the main cylinder.

[0053] Furthermore, such as Figure 4 As shown, the oil inlet of the third directional valve 31 is provided with a second shuttle valve 33. The first inlet of the second shuttle valve 33 is connected to the first interface A1, and the second inlet of the second shuttle valve 33 is connected to the main control oil port X1. The second shuttle valve 33 cooperates with the first shuttle valve 54 to further consume the oil pressure in the rod chamber of the hydraulic cylinder 2, ensuring that the pressure in the rod chamber is always lower than the safety threshold.

[0054] As an optional embodiment, such as Figure 1 and Figure 4 As shown, a safety valve 32 is connected in parallel with the return oil cartridge valve 3. The inlet of the safety valve 32 is connected to the rod chamber of the hydraulic cylinder 2, and the outlet of the safety valve 32 is connected to the main return oil port T1. The safety valve 32 can further serve as over-limit protection for the pressure of the rod chamber of the hydraulic cylinder 2. A maximum pressure threshold for the rod chamber of the hydraulic cylinder 2 can be set. When the pressure in the rod chamber exceeds the maximum pressure threshold, the safety valve 32 can be opened to drain the excess oil back to the main return oil port T1, further ensuring that the pressure in the rod chamber is always below the safety threshold, thus guaranteeing the safety performance of the hydraulic cylinder 2 during pressurization and pressure holding.

[0055] As an optional embodiment, such as Figure 1As shown, the directional control valve group includes a hydraulic filling valve 9 and a fourth directional valve. The hydraulic filling valve 9 has a first oil port and a second oil port. The first oil port of the hydraulic filling valve 9 is connected to the filling oil tank 1, and the second oil port of the hydraulic filling valve 9 is connected to the rodless chamber of the hydraulic cylinder 2. The fourth directional valve 91 is arranged between the X port of the hydraulic filling valve 9 and the main control oil port X1. The fourth directional valve 91 has at least a seventh position and an eighth position. In this embodiment, the fourth directional valve 91 is preferably a two-position four-way solenoid directional valve. The seventh position is the left position of the two-position four-way solenoid directional valve, and the eighth position is the right position of the two-position four-way solenoid directional valve, so as to use the fourth directional valve 91 to switch the hydraulic filling valve 9, realize the directional switching of the hydraulic filling valve 9, and realize the switching of the oil circuit direction between the filling oil tank 1 and the hydraulic cylinder 2.

[0056] Among them, such as Figure 1 and Figure 5 As shown, when the eighth position of the fourth directional valve 91 is energized, the X port of the hydraulic filling valve 9 is disconnected from the main control oil port X1, and the hydraulic filling valve 9 opens in the forward direction, ensuring that an extended filling pipeline 111 is formed between the filling oil tank 1 and the rodless chamber of the hydraulic cylinder 2. At this time, the filling oil tank 1 can fill the rodless chamber of the hydraulic cylinder 2 with oil, and cooperate with the extended return oil pipeline 112 to complete the rapid extension of the hydraulic cylinder 2; Figure 1 and Figure 6 As shown, when the seventh position of the fourth directional valve 91 is energized, the X port of the hydraulic filling valve 9 is connected to the main control oil port X1, and the hydraulic filling valve 9 is opened to ensure that a retraction return oil pipeline 122 is formed between the rodless chamber of the hydraulic cylinder 2 and the filling oil tank 1. At this time, the rodless chamber of the hydraulic cylinder 2 can return oil to the filling oil tank 1, which, together with the retraction filling oil pipeline 121, completes the rapid retraction of the hydraulic cylinder 2; or prevents the hydraulic oil in the filling oil tank 1 from entering the rodless chamber of the hydraulic cylinder 2, further ensuring the pressure application accuracy and pressure holding accuracy.

[0057] Accordingly, a second aspect of the present invention provides a hydraulic press, which includes the hydraulic cylinder proportional control circuit described in any of the above embodiments. All the beneficial effects of the hydraulic press including the above hydraulic cylinder proportional control circuit will not be repeated here.

[0058] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A proportional control circuit for a hydraulic cylinder, characterized in that, The system includes a filling oil tank, a hydraulic cylinder, an oil pipe assembly, and a control valve assembly. The filling oil tank is connected to the hydraulic cylinder via a directional control valve assembly. The oil pipe assembly has a first interface, a second interface, a main return port, a main pump port, a main control port, and a main drain port. The first interface is connected to the rod-side chamber of the hydraulic cylinder, and the second interface is connected to the rodless chamber of the hydraulic cylinder. The directional control valve assembly is used to switch the direction of the oil circuit between the filling oil tank and the hydraulic cylinder. The control valve group includes a return oil cartridge valve, a first cartridge valve group, a second cartridge valve group, and a proportional valve. The main return oil port is connected to the first interface through the return oil cartridge valve. The main pump port and the main return port are switched to be connected to the A port of the proportional valve through the first cartridge valve group, and the first interface and the second interface are switched to be connected to the B port of the proportional valve through the second cartridge valve group. The main control port is connected to the control ports of the first cartridge valve group and the second cartridge valve group, respectively, and the control ports of the first cartridge valve group and the second cartridge valve group are connected to the main drain port. The proportional valve is used to proportionally control the flow rate of the oil circuit between the first cartridge valve group and the second cartridge valve group.

2. The hydraulic cylinder proportional control circuit as described in claim 1, characterized in that, The first cartridge valve assembly includes a second cartridge valve and a third cartridge valve. Port A of the second cartridge valve is connected to the main return port, and port A of the third cartridge valve is connected to the main pump port. Ports B of the second cartridge valve and the third cartridge valve are connected to the proportional valve switching connection. The main control port is switched to be connected to the X port of the second cartridge valve and the X port of the third cartridge valve; The X port of the second cartridge valve and the X port of the third cartridge valve are switched to be connected to the main drain port.

3. The hydraulic cylinder proportional control circuit as described in claim 2, characterized in that, A first directional valve is arranged between the X port of the second cartridge valve and the X port of the third cartridge valve, and the first directional valve has at least a first working position and a second working position. When the first station is powered on, the X port of the second cartridge valve is connected to the main drain port, and the X port of the third cartridge valve is connected to the main control port. When the first station is powered on, the X port of the second cartridge valve is connected to the main control oil port, and the X port of the third cartridge valve is connected to the main drain port.

4. The hydraulic cylinder proportional control circuit as described in claim 1, characterized in that, The second cartridge valve assembly includes a fourth cartridge valve and a fifth cartridge valve. The B port of the fourth cartridge valve is connected to the first interface, the B port of the fifth cartridge valve is connected to the second interface, and the A ports of the fourth cartridge valve and the A ports of the fifth cartridge valve are switched to be connected to the B port of the proportional valve. The main control port is switched to be connected to the X port of the fourth cartridge valve and the X port of the fifth cartridge valve; The X port of the fourth cartridge valve and the X port of the fifth cartridge valve are switched to be connected to the main drain port.

5. The hydraulic cylinder proportional control circuit as described in claim 4, characterized in that, A second directional valve is arranged between the X port of the fourth cartridge valve and the X port of the fifth cartridge valve, and the second directional valve has at least a third position and a fourth position. When the third station is energized, the X port of the fourth cartridge valve is connected to the main control oil port, and the X port of the fifth cartridge valve is connected to the main drain port. When the fourth station is energized, the X port of the fourth cartridge valve is connected to the main drain port, and the X port of the fifth cartridge valve is connected to the main control port.

6. The hydraulic cylinder proportional control circuit as described in claim 5, characterized in that, The oil inlet of the second reversing valve is provided with a first shuttle valve. The first inlet of the first shuttle valve is connected to the first interface, and the second inlet of the first shuttle valve is connected to the main control oil port.

7. The hydraulic cylinder proportional control circuit as described in claim 4, characterized in that, A pressure sensor is provided between port B of the fifth cartridge valve and the second interface, and a displacement sensor is provided in the hydraulic cylinder.

8. The hydraulic cylinder proportional control circuit as described in claim 1, characterized in that, The A port of the return oil cartridge valve is connected to the main return oil port, and the B port of the return oil cartridge valve is connected to the first interface. The X port of the return oil cartridge valve is equipped with a third directional valve. The third directional valve has at least a fifth position and a sixth position. When the sixth position is energized, the X port of the return oil cartridge valve is connected to the main control oil port. When the fifth position is energized, the X port of the return oil cartridge valve is connected to the main drain port.

9. The hydraulic cylinder proportional control circuit as described in claim 8, characterized in that, The return oil cartridge valve is connected in parallel with a safety valve. The inlet of the safety valve is connected to the rod chamber of the hydraulic cylinder, and the outlet of the safety valve is connected to the main return oil port.

10. The hydraulic cylinder proportional control circuit as described in claim 1, characterized in that, The directional control valve group includes a hydraulic filling valve and a fourth directional valve. The hydraulic filling valve has a first oil port and a second oil port. The first oil port is connected to the filling oil tank, and the second oil port is connected to the rodless chamber of the hydraulic cylinder. The fourth directional valve is arranged between the X port of the hydraulic filling valve and the main control oil port. The fourth directional valve has at least a seventh position and an eighth position. When the eighth station is powered on, the X port of the hydraulic filling valve is disconnected from the main control oil port; When the seventh station is powered on, the X port of the hydraulic filling valve is connected to the main control oil port.

11. A hydraulic press, characterized in that, Includes the hydraulic cylinder proportional control circuit according to any one of claims 1 to 10.

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