Energy-saving hydraulic cushion control system and method

Abstract

The invention provides an energy-saving hydraulic cushion control system and method, and relates to the technical field of hydraulic cushion control. The system comprises a hydraulic cylinder, an inlet valve, an outlet valve, an energy storage device, an energy recovery electric pump, a main energy storage device, a main electric pump and a controller. An inlet of the inlet valve is connected with the main energy accumulator, and an outlet of the inlet valve is connected with a rodless cavity of the hydraulic cylinder. An inlet of the outlet valve is connected with a rodless cavity of the hydraulic cylinder, and an outlet of the outlet valve is connected with the energy storage device. The energy storage device is also connected with the energy recovery electric pump; the energy recovery electric pump is connected with the main energy accumulator; the main energy accumulator is further connected with an outlet of the main electric pump. The controller controls the inlet valve, the energy recovery electric pump, the main electric pump and the outlet valve according to the piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main energy accumulator and the pressure of the rodless cavity of the hydraulic cylinder. The energy efficiency of a traditional servo valve control hydraulic system can be improved, and the defects of a pump control hydraulic system are overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic cushion control, and particularly relates to an energy-saving hydraulic cushion control system and method. BACKGROUND

[0002] The hydraulic cushion technology is mainly applied to numerical control stamping equipment, and its core function is to realize the buffering when the mold is contacted through pre-acceleration control, so as to reduce the impact pressure, improve the workpiece surface quality and the mold life. The current technical route mainly includes two types of servo valve control hydraulic system and pump control hydraulic system: as shown in Figure 1 , the servo valve control system realizes precise speed control through high-frequency servo valve adjustment of oil flow, and as shown in Figure 2 , the pump control system directly drives by using an electro-hydraulic servo pump, and has a higher energy efficiency ratio.

[0003] Among them, the pump control hydraulic system has an advantage in energy efficiency. The advantages can be summarized as follows: 1) the pump control hydraulic system directly drives the hydraulic pump through the servo motor, which fundamentally eliminates the energy loss caused by throttling and overflow in the traditional servo valve control hydraulic system. The recovered electric energy can be exchanged and reused between different motors in the system through the common DC bus technology, or stored through the energy storage capacitor, which greatly improves the overall energy utilization efficiency. 2) Due to the substantial reduction of heat energy generated by hydraulic oil overflow and throttling, the system temperature rise problem is effectively alleviated, and the dependence on additional cooling devices is reduced or even cancelled, thereby saving the production cost and energy consumption from another aspect.

[0004] But there are several aspects of the following shortcomings: 1) high initial complexity of the system, cost increase: electric energy recovery system, especially the common DC bus and energy storage capacitor hybrid scheme, need to increase the electric reactor, rectifier, inverter, capacitor and a large number of power electronic components. This not only increases the complexity of the system and the initial investment cost, but also puts forward higher requirements for the design, installation, debugging and maintenance of the system. 2) rely on effective energy regulation strategy: energy storage capacitor to achieve effective "peak clipping and valley filling" function, must be equipped with and matched, accurate energy regulation strategy. If the strategy is not good, the recovery efficiency cannot be maximized, and even the stability of the system operation may be affected. Developing such a strategy itself is a technical challenge. 3) energy conversion times, energy conversion loss: energy recovery process is not 100% efficient. Electric energy needs to be converted between mechanical energy, hydraulic energy and electric energy, and needs to pass through power electronic devices during recovery, and each step of conversion will be accompanied by a certain amount of energy loss. 4) pump control hydraulic system response is slow, and the pressure control precision is lower than that of valve control. The inherent mechanical inertia leads to slow response and low pressure control precision: the core execution element of the pump control hydraulic system is the servo motor and the hydraulic pump. The rotor of the servo motor and the plunger of the hydraulic pump have large mechanical inertia, and the speed regulation (acceleration / deceleration) of the rotor cannot be completed instantaneously like the electromagnetic valve core. This results in a delay in the response of the pump control hydraulic system to the command, especially in scenarios where pressure needs to be quickly established or released. SUMMARY

[0005] The energy-saving hydraulic pad control system and method provided by the embodiments of the present application solve the problems of low energy efficiency of the traditional servo valve control hydraulic system, high cost of the electric energy recovery system, complex control of the pump control hydraulic system, and low pressure control response of the pump control hydraulic system compared with the valve control.

[0006] In a first aspect, the embodiments of the present application provide an energy-saving hydraulic pad control system, comprising: a hydraulic cylinder, an inlet valve, an outlet valve, an energy storage accumulator, an energy recovery electric pump, a main accumulator, a main electric pump and a controller. The inlet of the inlet valve is connected with the main accumulator, and the outlet of the inlet valve is connected with the rodless chamber of the hydraulic cylinder. The inlet of the outlet valve is connected with the rodless chamber of the hydraulic cylinder, and the outlet of the outlet valve is connected with the energy storage accumulator. The energy storage accumulator is also connected with the energy recovery electric pump. The energy recovery electric pump is connected with the main accumulator. The main accumulator is also connected with the outlet of the main electric pump. The controller controls the inlet valve, the energy recovery motor pump, the main motor pump and the outlet valve according to the piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main accumulator and the pressure of the rodless cavity of the hydraulic cylinder.

[0007] In a possible implementation, the hydraulic system further comprises a first one-way valve. The energy recovery motor pump is connected with the main accumulator through the first one-way valve, and the flow direction of the first one-way valve is from the energy recovery motor pump to the main accumulator.

[0008] In a possible implementation, the hydraulic system further comprises a low-pressure compensator. The energy storage accumulator is further connected with the low-pressure compensator.

[0009] In a possible implementation, the hydraulic system further comprises a first pressure sensor, a second pressure sensor and a third pressure sensor. The first pressure sensor is configured to acquire the pressure of the rodless cavity of the hydraulic cylinder and send the pressure of the rodless cavity of the hydraulic cylinder to the controller. The second pressure sensor is configured to acquire the pressure of the energy storage accumulator and send the pressure of the energy storage accumulator to the controller. The third pressure sensor is configured to acquire the pressure of the main accumulator and send the pressure of the main accumulator to the controller.

[0010] In a possible implementation, the controller is specifically configured to: In the process of the piston rising of the hydraulic cylinder, the controller controls the outlet valve to be closed, the inlet valve to be opened, the start and stop of the energy recovery motor pump according to a first rule based on the pressure of the energy storage accumulator, the start and stop of the main motor pump based on the pressure of the main accumulator, and whether the inlet valve is closed based on the piston displacement of the hydraulic cylinder. In the process of the press slide descending, the controller controls the opening size of the outlet valve based on the pressure of the rodless cavity of the hydraulic cylinder and controls the start and stop of the energy recovery motor pump according to a second rule based on the pressure of the energy storage accumulator.

[0011] In a possible implementation, the start and stop of the energy recovery motor pump according to the pressure of the energy storage accumulator according to a first rule comprises: determining whether the pressure of the energy storage accumulator is less than the maximum pressure of the low-pressure compensator; if the pressure of the energy storage accumulator is greater than the maximum pressure of the low-pressure compensator, controlling the energy recovery motor pump to start; If the pressure of the energy storage accumulator is less than or equal to the maximum pressure of the low pressure compensator, the energy recovery electric pump is controlled to stop.

[0012] In a possible implementation, the starting and stopping of the main electric pump is controlled according to the pressure of the main accumulator, including: The pressure of the main accumulator is compared with a preset lower pressure limit and a preset upper pressure limit, respectively; If the pressure of the main accumulator is lower than the preset lower pressure limit, the main electric pump is controlled to start; If the pressure of the main accumulator reaches the preset upper pressure limit, the main electric pump is controlled to stop.

[0013] In a possible implementation, whether the inlet valve is closed is controlled according to the piston displacement of the hydraulic cylinder, including: It is judged whether the piston displacement of the hydraulic cylinder reaches a set displacement; If the piston displacement of the hydraulic cylinder reaches the set displacement, the inlet valve is controlled to be closed; If the piston displacement of the hydraulic cylinder does not reach the set displacement, the inlet valve is controlled to remain open.

[0014] In a possible implementation, the starting and stopping of the energy recovery electric pump is controlled according to the pressure of the energy storage accumulator according to a second rule, including: The pressure of the energy storage accumulator is compared with an ideal upper pressure limit and an ideal lower pressure limit, respectively; If the pressure of the energy storage accumulator is greater than the ideal upper pressure limit, the energy recovery electric pump is controlled to start; If the pressure of the energy storage accumulator is less than the ideal lower pressure limit, the energy recovery electric pump is controlled to stop.

[0015] In the second aspect, the embodiments of the present application provide an energy-saving hydraulic pad control method, which is applied to the energy-saving hydraulic pad control system in the first aspect or any possible implementation of the first aspect, and the method includes: The piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main accumulator and the pressure of the rodless cavity of the hydraulic cylinder are received; In the piston rising process of the hydraulic cylinder, the outlet valve is controlled to be closed, the inlet valve is controlled to be open, the starting and stopping of the energy recovery electric pump is controlled according to the pressure of the energy storage accumulator according to a first rule, the starting and stopping of the main electric pump is controlled according to the pressure of the main accumulator, and whether the inlet valve is closed is controlled according to the piston displacement of the hydraulic cylinder; During the process of the press slide descending, the opening size of the outlet valve is controlled according to the pressure of the rodless cavity of the hydraulic cylinder, and the start and stop of the energy recovery electric pump are controlled according to the pressure of the energy storage accumulator according to a second rule.

[0016] The embodiment of the present application provides an energy-saving hydraulic cushion control system and method, which can realize independent control of inlet and outlet oil of a control cavity by replacing a servo valve in a servo valve controlled hydraulic system with an inlet valve and an outlet valve, and can decouple control and performance control of energy regeneration, separate them in different components and different stages, and then realize hydraulic energy recovery, energy regeneration, and improvement of system efficiency, and avoid the defects of a pump controlled electric energy recovery system which needs to increase a large number of power electronic components such as electric reactors, rectifiers, inverters and capacitors. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural principle diagram of a conventional servo valve controlled hydraulic system provided by the embodiment of the present application; Figure 2 is a structural principle diagram of a conventional pump controlled hydraulic system provided by the embodiment of the present application; Figure 3 is a structural principle diagram of an energy-saving hydraulic cushion control system provided by the embodiment of the present application; Figure 4 is an implementation flowchart of an energy-saving hydraulic cushion control method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0018] In order for those skilled in the art to better understand the present scheme, the technical solutions in the embodiments of the present scheme will be clearly described below in combination with the drawings in the embodiments of the present scheme. Obviously, the described embodiments are part of the embodiments of the present scheme, rather than all the embodiments. Based on the embodiments in the present scheme, all other embodiments obtained by those skilled in the art without creative labor should be within the protection scope of the present scheme.

[0019] The terms "include", and other any variants thereof, in the specification and claims of the present scheme and the above-mentioned drawings, refer to "include but not limited to", and are intended to cover non-exclusive inclusion, and are not limited to the examples listed in the text. In addition, the terms "first" and "second" and the like are used to distinguish different objects, rather than to describe a specific order.

[0020] The implementation of the present application will be described in detail below in combination with specific drawings: In combination Figure 1As shown, the energy consumption of a servo valve-controlled hydraulic system mainly manifests in the following aspects: During the press's downward movement, the system needs to continuously supply oil to overcome the load's gravity. Traditional valve-controlled systems use throttle valves and relief valves for speed and pressure control, resulting in a significant amount of hydraulic energy being lost as heat through throttling and relief. During the pressure holding phase, the system needs to continuously overflow to maintain the working pressure, causing long-term energy waste. During the return stroke and depressurization, hydraulic energy is directly consumed through the pressure relief valve without being effectively utilized. These energy losses not only reduce system efficiency but also cause oil temperature to rise, requiring additional cooling devices and further increasing energy consumption.

[0021] Currently, the main energy-saving methods for compressor energy recovery include: 1) Replace the valve control system with a pump-controlled hydraulic system. The hydraulic pump is directly driven by a servo motor, eliminating throttling and overflow losses and fundamentally reducing energy consumption.

[0022] 2) Common DC bus technology transmits the feedback power generated by multiple servo motors during braking to the DC bus for use by other motors, realizing internal energy circulation.

[0023] 3) Capacitor energy storage technology uses supercapacitors to store the feedback energy generated during braking, which is then released when the system needs peak power, reducing dependence on the power grid.

[0024] 4) Hybrid energy-saving system, which combines the advantages of common DC bus and capacitor energy storage, achieves "peak shaving and valley filling" of DC bus voltage through energy regulation strategy, further improving energy-saving effect.

[0025] Current research on energy conservation in hydraulic cushions is in a phase of rapid development. Domestic research mainly focuses on the optimized design of pump-controlled hydraulic systems, such as the hybrid system of a common DC bus and capacitor energy storage proposed by Yanshan University, whose energy-saving efficiency has been verified through simulation and experiments. Internationally, Osaka University in Japan has studied the application of flywheel energy storage and capacitor energy storage in servo presses, concluding that capacitor energy storage is a better choice. Institutions such as the University of Florence in Italy are also exploring optimized control strategies for electro-hydraulic hybrid power systems. These studies not only focus on individual energy-saving technologies but also emphasize system-level energy management and coordinated control, achieving precise matching of energy supply and demand through intelligent algorithms, thus driving the development of hydraulic cushions towards high efficiency and low carbon emissions.

[0026] However, pump-controlled hydraulic systems also have the following drawbacks: 1) High initial system complexity and increased cost: Energy recovery systems, especially those combining a common DC bus with energy storage capacitors, require a large number of power electronic components such as reactors, rectifiers, inverters, and capacitors. This not only increases the system's complexity and initial investment cost but also places higher demands on the system's design, installation, commissioning, and maintenance.

[0027] 2) Reliance on effective energy regulation strategies: For energy storage capacitors to achieve effective peak shaving and valley filling, they must be equipped with matching and precise energy regulation strategies. If the strategy is inadequate, the recovery efficiency cannot be maximized, and it may even affect the stability of system operation. Developing such a strategy is itself a technical challenge.

[0028] 3) Numerous energy conversions and energy losses: The energy recovery process is not 100% efficient. Electrical energy needs to be converted multiple times between mechanical energy, hydraulic energy, and electrical energy, and it also needs to be converted by power electronic devices during recovery. Each conversion step is accompanied by a certain amount of energy loss.

[0029] 4) Pump-controlled hydraulic systems have a slower response and lower pressure control accuracy compared to valve-controlled systems. Inherent mechanical inertia leads to a slower response and lower pressure control accuracy: The core actuators of a pump-controlled hydraulic system are a servo motor and a hydraulic pump. The rotor of the servo motor and the plunger of the hydraulic pump have significant mechanical inertia, and their speed regulation (acceleration / deceleration) cannot be completed instantaneously like an electromagnet driving a valve spool. This results in a delay in the response of the pump-controlled hydraulic system to commands, especially in scenarios requiring rapid pressure build-up or release.

[0030] Therefore, embodiments of the present invention provide an energy-saving hydraulic cushion control system, referring to... Figure 3 The energy-saving hydraulic cushion control system includes: a hydraulic cylinder 1, an inlet valve 2, an outlet valve 3, an energy storage accumulator 4, an energy recovery electric pump 5, a main accumulator 6, a main electric pump 7, and a controller.

[0031] The inlet of inlet valve 2 is connected to the main accumulator 6, and the outlet of inlet valve 2 is connected to the rodless chamber of hydraulic cylinder 1.

[0032] The inlet of outlet valve 3 is connected to the rodless chamber of hydraulic cylinder 1, and the outlet of outlet valve 3 is connected to energy storage accumulator 4.

[0033] The energy storage device 4 is also connected to the energy recovery electric pump 5.

[0034] The energy recovery electric pump 5 is connected to the main accumulator 6.

[0035] The main accumulator 6 is also connected to the outlet of the main electric pump 7.

[0036] The controller controls the inlet valve 2, the energy recovery electric pump 5, the main electric pump 7, and the outlet valve 3 based on the piston displacement of the hydraulic cylinder 1, the pressure of the energy storage accumulator 4, the pressure of the main accumulator 6, and the pressure of the rodless chamber of the hydraulic cylinder 1.

[0037] In this embodiment, two two-position two-way servo valves (i.e., inlet valve 2 and outlet valve 3) are used to replace the two-position three-way servo valves in the original valve control system. The inlet of inlet valve 2 is the main accumulator 6, and the outlet is the rodless chamber of hydraulic cylinder 1. The inlet of outlet valve 3 is the rodless chamber of hydraulic cylinder 1, and the outlet is the energy storage accumulator 4.

[0038] In this embodiment, the controller receives the pressure of the main accumulator 6, the pressure of the rodless chamber, the piston displacement of the hydraulic cylinder 1, and the pressure of the energy storage accumulator 4, and controls the inlet valve 2, the outlet valve 3, the main electric pump 7, and the energy recovery electric pump 5.

[0039] For example, such as Figure 3 As shown, this energy-saving hydraulic cushion control system also includes: a first check valve 8, through which the energy recovery electric pump 5 is connected to the main accumulator 6, and the flow direction of the first check valve 8 is from the energy recovery electric pump 5 to the main accumulator 6. By setting the first check valve 8, backflow of the medium can be prevented from causing the pump to reverse when the pump stops.

[0040] For example, such as Figure 3 As shown, the energy-saving hydraulic cushion control system also includes a low-pressure compensator 9, and the energy storage accumulator 4 is also connected to the low-pressure compensator 9.

[0041] For example, such as Figure 3 As shown, the energy-saving hydraulic cushion control system also includes a first pressure sensor 10, a second pressure sensor 11, and a third pressure sensor 12.

[0042] The first pressure sensor 10 is used to acquire the pressure of the rodless chamber of the hydraulic cylinder 1 and send the pressure of the rodless chamber of the hydraulic cylinder 1 to the controller.

[0043] The second pressure sensor 11 is used to acquire the pressure of the energy storage accumulator 4 and send the pressure of the energy storage accumulator 4 to the controller.

[0044] The third pressure sensor 12 is used to acquire the pressure of the main accumulator 6 and send the pressure of the main accumulator 6 to the controller.

[0045] In one embodiment, the controller is specifically used for: During the piston rise of hydraulic cylinder 1, the outlet valve 3 is closed and the inlet valve 2 is opened. The energy recovery electric pump 5 is started and stopped according to the first rule based on the pressure of the energy storage accumulator 4. The main electric pump 7 is started and stopped according to the pressure of the main accumulator 6. The inlet valve 2 is closed according to the piston displacement of hydraulic cylinder 1.

[0046] During the descent of the press slide, the opening size of the outlet valve 3 is controlled according to the pressure of the rodless chamber of the hydraulic cylinder 1, and the start and stop of the energy recovery electric pump 5 are controlled according to the pressure of the energy storage accumulator 4 according to the second rule.

[0047] For example, controlling the start and stop of the energy recovery electric pump 5 according to the pressure of the energy storage tank 4 in accordance with a first rule may include: Determine whether the pressure of the energy storage accumulator 4 is less than the maximum pressure of the low-pressure compensator 9.

[0048] If the pressure of the energy storage accumulator 4 is greater than the maximum pressure of the low-pressure compensator 9, the energy recovery electric pump 5 will be started.

[0049] If the pressure of the energy storage accumulator 4 is less than or equal to the maximum pressure of the low-pressure compensator 9, the control energy recovery electric pump 5 will stop.

[0050] For example, controlling the start and stop of the main electric pump 7 based on the pressure of the main accumulator 6 may include: The pressure of the main accumulator 6 is compared with the preset lower pressure limit and the preset upper pressure limit, respectively.

[0051] If the pressure of the main accumulator 6 is lower than the preset lower pressure limit, the main electric pump 7 will be started.

[0052] If the pressure in the main accumulator 6 reaches the preset pressure limit, the main electric pump 7 will be stopped.

[0053] For example, controlling whether the inlet valve 2 is closed based on the piston displacement of the hydraulic cylinder 1 may include: Determine whether the piston displacement of hydraulic cylinder 1 has reached the set displacement.

[0054] If the piston displacement of hydraulic cylinder 1 reaches the set displacement, control inlet valve 2 to close.

[0055] If the piston displacement of hydraulic cylinder 1 does not reach the set displacement, control inlet valve 2 remains open.

[0056] For example, controlling the start and stop of the energy recovery electric pump 5 according to the pressure of the energy storage accumulator 4 in accordance with the second rule may include: The pressure of the energy storage device 4 is compared with the upper limit of the ideal pressure and the lower limit of the ideal pressure, respectively.

[0057] If the pressure in the energy storage accumulator 4 is greater than the ideal pressure limit, the energy recovery electric pump 5 will be started.

[0058] If the pressure in the energy storage accumulator 4 is less than the lower limit of the ideal pressure, the control energy recovery electric pump 5 will stop.

[0059] In this embodiment, the specific control process of the controller is as follows: 1) During the operation of the hydraulic cushion, the piston of hydraulic cylinder 1 first needs to rise to the designated position, which can be achieved using position control mode. In this mode, outlet valve 3 needs to be closed and inlet valve 2 needs to be opened. Then, the hydraulic oil in the main accumulator 6 enters the rodless chamber of hydraulic cylinder 1, pushing the piston of hydraulic cylinder 1 to rise and lift the mold until it reaches the designated position. Then, inlet valve 2 closes, and the mold waits for the press to descend.

[0060] In position control mode, during the piston rise of hydraulic cylinder 1, in addition to monitoring the piston displacement of hydraulic cylinder 1 to control whether the inlet valve is closed, the energy recovery electric pump 5 and the main electric pump 7 are simultaneously controlled. Specifically, the energy recovery electric pump 5 discharges oil from the energy storage accumulator 4 to the main accumulator 6 until all fluid in the energy storage accumulator 4 is discharged and the pressure of the energy storage accumulator 4 drops below the maximum pressure of the low-pressure compensator 9, at which point the energy recovery electric pump 5 stops. The main electric pump 7's main function is to maintain the pressure of the main accumulator 6. The control logic is to set a preset upper pressure limit and a preset lower pressure limit. When the pressure of the main accumulator 6 is lower than the preset lower pressure limit, the main electric pump 7 is started and pressurized until the preset upper pressure limit is reached, at which point the main electric pump 7 stops. The main electric pump 7 is restarted when the pressure of the main accumulator 6 falls below the preset lower pressure limit again.

[0061] 2) During the descent of the press slide, the upper mold is driven to contact the pressing edge of the lower mold, and then the plate on the pressing edge is clamped and pulled up to the lower mold. During the descent, the pressure in the rodless chamber is controlled to the required pressure by controlling the opening of the outlet valve 3, thereby ensuring the quality of workpiece stretching. The control target in this process is the pressing force.

[0062] During the blank holder force control process, the outlet of outlet valve 3 is the energy storage accumulator 4. During the press's downward movement, the oil in hydraulic cylinder 1 enters the energy storage accumulator 4, realizing energy regeneration during the press's downward movement. This regeneration process is a direct transfer from hydraulic energy to hydraulic energy without energy conversion, resulting in high regeneration efficiency. This process requires synchronous control of the energy recovery electric pump 5 to maintain the pressure of the energy storage accumulator 4 within an ideal range (i.e., between the ideal lower pressure limit and the ideal upper pressure limit), thereby improving energy regeneration efficiency and reducing throttling losses at outlet valve 3.

[0063] 3) After the press reaches its lowest point, the next cycle begins. The press rises, and the hydraulic cylinder 1 rises to the designated position by controlling the inlet valve 2. During the rising process and while waiting for the press to fall again, the energy recovery electric pump 5 is controlled to discharge the oil in the energy storage accumulator 4 to the main energy storage accumulator 6, supplying the regenerated energy to the rising process, realizing the reuse of stored energy, thereby reducing the working demand of the main electric pump 7.

[0064] This invention addresses the low energy efficiency of traditional servo valve-controlled hydraulic systems and the high cost, complex control, and lower pressure control response of pump-controlled hydraulic systems compared to valve-controlled systems with energy recovery systems. It constructs an energy-saving hydraulic cushion control system using a hydraulic cylinder, inlet valve, outlet valve, energy accumulator, energy recovery electric pump, main accumulator, main electric pump, and controller. This system enables the regeneration of press energy directly from hydraulic energy to hydraulic energy, without energy conversion, resulting in high energy regeneration efficiency. Only one additional energy accumulator and energy recovery electric pump are needed, leading to minimal cost increase. Furthermore, the energy regeneration control and performance control are decoupled, operating in different components and stages, facilitating control implementation. Additionally, two two-position two-way proportional valves replace the original three-position three-way proportional valve. Two-position two-way valves have a simpler structure and lower cost; replacing one valve with two valves results in minimal cost increase. Moreover, both position and pressure control utilize valve control, ensuring both speed and accuracy.

[0065] Another embodiment of the present invention provides an energy-saving hydraulic cushion control method, applied to the energy-saving hydraulic cushion control system as described in the above embodiments, such as... Figure 4 As shown, the method includes: Step 401: Receive the piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main accumulator, and the pressure of the rodless chamber of the hydraulic cylinder.

[0066] Step 402: During the piston rise of the hydraulic cylinder, the outlet valve is closed and the inlet valve is opened. The energy recovery electric pump is started and stopped according to the first rule based on the pressure of the energy storage accumulator. The main electric pump is started and stopped according to the pressure of the main accumulator. The inlet valve is closed according to the piston displacement of the hydraulic cylinder.

[0067] Step 403: During the descent of the press slide, the opening size of the outlet valve is controlled according to the pressure in the rodless chamber of the hydraulic cylinder, and the start and stop of the energy recovery electric pump are controlled according to the second rule based on the pressure of the energy storage accumulator.

[0068] The energy-saving hydraulic cushion control method provided in this embodiment of the invention has the same beneficial effects as the energy-saving hydraulic cushion control system described above, and will not be repeated here.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An energy-saving hydraulic cushion control system, characterized in that, include: Hydraulic cylinders, inlet valves, outlet valves, energy storage accumulators, energy recovery electric pumps, main accumulators, main electric pumps, and controllers; The inlet of the inlet valve is connected to the main accumulator, and the outlet of the inlet valve is connected to the rodless chamber of the hydraulic cylinder. The inlet of the outlet valve is connected to the rodless chamber of the hydraulic cylinder, and the outlet of the outlet valve is connected to the energy storage accumulator. The energy storage device is also connected to the energy recovery electric pump; The energy recovery electric pump is connected to the main energy accumulator; The main accumulator is also connected to the outlet of the main electric pump; The controller controls the inlet valve, the energy recovery electric pump, the main electric pump, and the outlet valve based on the piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main accumulator, and the pressure of the rodless chamber of the hydraulic cylinder.

2. The energy-saving hydraulic cushion control system as described in claim 1, characterized in that, Also includes: First check valve; The energy recovery electric pump is connected to the main accumulator through the first one-way valve, and the flow direction of the first one-way valve is from the energy recovery electric pump to the main accumulator.

3. The energy-saving hydraulic cushion control system as described in claim 1, characterized in that, It also includes low-voltage compensators; The energy storage device is also connected to the low-voltage compensator.

4. The energy-saving hydraulic cushion control system as described in claim 1, characterized in that, It also includes a first pressure sensor, a second pressure sensor, and a third pressure sensor; The first pressure sensor is used to acquire the pressure of the rodless chamber of the hydraulic cylinder and send the pressure of the rodless chamber of the hydraulic cylinder to the controller; The second pressure sensor is used to acquire the pressure of the energy storage device and send the pressure of the energy storage device to the controller; The third pressure sensor is used to acquire the pressure of the main accumulator and send the pressure of the main accumulator to the controller.

5. The energy-saving hydraulic cushion control system as described in claim 1, characterized in that, The controller is specifically used for: During the piston rise of the hydraulic cylinder, the outlet valve is controlled to close and the inlet valve is controlled to open. The energy recovery electric pump is started and stopped according to the pressure of the energy storage accumulator according to the first rule. The main electric pump is started and stopped according to the pressure of the main accumulator. The inlet valve is controlled to close according to the piston displacement of the hydraulic cylinder. During the descent of the press slide, the opening size of the outlet valve is controlled according to the pressure in the rodless chamber of the hydraulic cylinder, and the start and stop of the energy recovery electric pump are controlled according to the pressure of the energy storage accumulator according to the second rule.

6. The energy-saving hydraulic cushion control system as described in claim 5, characterized in that, The starting and stopping of the energy recovery electric pump are controlled according to the pressure of the energy storage device in accordance with a first rule, including: Determine whether the pressure of the energy storage device is less than the maximum pressure of the low-pressure compensator; If the pressure of the energy storage device is greater than the maximum pressure of the low-pressure compensator, then the energy recovery electric pump is controlled to start. If the pressure of the energy storage device is less than or equal to the maximum pressure of the low-pressure compensator, the energy recovery electric pump is controlled to stop.

7. The energy-saving hydraulic cushion control system as described in claim 5, characterized in that, Controlling the start and stop of the main electric pump based on the pressure of the main accumulator includes: The pressure of the main accumulator is compared with the preset lower pressure limit and the preset upper pressure limit, respectively. If the pressure of the main accumulator is lower than the preset lower pressure limit, the main electric pump is controlled to start. If the pressure of the main accumulator reaches the preset pressure limit, the main electric pump is controlled to stop.

8. The energy-saving hydraulic cushion control system as described in claim 5, characterized in that, Controlling whether the inlet valve is closed based on the piston displacement of the hydraulic cylinder includes: Determine whether the piston displacement of the hydraulic cylinder has reached the set displacement; If the piston displacement of the hydraulic cylinder reaches the set displacement, the inlet valve is controlled to close. If the piston displacement of the hydraulic cylinder does not reach the set displacement, the inlet valve is kept open.

9. The energy-saving hydraulic cushion control system as described in claim 5, characterized in that, The starting and stopping of the energy recovery electric pump are controlled according to the pressure of the energy storage device in accordance with the second rule, including: The pressure of the energy storage device is compared with the upper limit of the ideal pressure and the lower limit of the ideal pressure, respectively. If the pressure of the energy storage device is greater than the upper limit of the ideal pressure, then the energy recovery electric pump is started. If the pressure of the energy storage device is less than the ideal lower pressure limit, the energy recovery electric pump is controlled to stop.

10. An energy-saving hydraulic cushion control method, characterized in that, The method, applied to the energy-saving hydraulic cushion control system as described in any one of claims 1-9, comprises: It receives the piston displacement of the hydraulic cylinder, the pressure of the energy storage accumulator, the pressure of the main accumulator, and the pressure of the rodless chamber of the hydraulic cylinder; During the piston rise of the hydraulic cylinder, the outlet valve is closed and the inlet valve is opened. The energy recovery electric pump is started and stopped according to the first rule based on the pressure of the energy storage accumulator. The main electric pump is started and stopped according to the pressure of the main accumulator. The inlet valve is closed according to the piston displacement of the hydraulic cylinder. During the descent of the press slide, the opening size of the outlet valve is controlled according to the pressure in the rodless chamber of the hydraulic cylinder, and the start and stop of the energy recovery electric pump are controlled according to the pressure of the energy storage accumulator according to the second rule.

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