A digital piston capable of adjusting dynamic characteristics and pressure shock and a control method thereof

Abstract

The present invention discloses a digital piston with adjustable dynamic characteristics and pressure shock and a control method thereof. The present invention connects the oil suction port and the oil discharge port of the piston respectively through two high-speed switch valves, and adjusts the dynamic characteristics of the high-speed switch valve according to the current movement speed of the piston, so that when the piston enters the oil discharge movement state and the movement speed is fast, the dynamic characteristics of the high-speed switch valve are adjusted to slow down its opening and closing, thereby reducing the pressure shock on the cavity caused by the high-speed opening of the high-speed switch valve when the piston moves at high speed, and reducing damage to components such as the piston and the high-speed switch valve; when the piston enters the oil suction movement state and the movement speed is slow, the dynamic characteristics of the high-speed switch valve are adjusted to make it open and close faster, which can greatly enhance the efficiency and flow response characteristics of the digital piston and greatly reduce the time for the digital pump to suck and discharge oil.

Description

Technical Field

[0001] The invention relates to the field of piston control, and in particular to a control method for a digital piston that adjusts dynamic characteristics and pressure shocks. Background Art

[0002] The hydraulic pump is driven by a prime mover, converting the input mechanical energy into liquid pressure energy, and then inputting it into the system in the form of pressure and flow. It is often used as a hydraulic source for high-pressure systems and is widely used in industries such as metallurgy, mining, engineering machinery, ships, and aviation. The piston of a traditional hydraulic pump is driven by a crankshaft. Due to the limitations of the crank-connecting rod mechanism, it has a series of problems such as poor suction performance, large flow pulsation, and low mechanical efficiency.

[0003] The digital piston can open and close the cavity in real time by using a high-speed switching valve controlled by an embedded computer, thereby achieving independent suction, pressure and discharge of oil in the cavity. It can also unload the cavity in real time when work is not necessary. Therefore, it can overcome the problem of narrow high-efficiency zone of traditional hydraulic pumps and greatly improve the volumetric efficiency and mechanical efficiency of the pump.

[0004] However, the performance of the digital piston is largely subject to the performance of the high-speed switch valve product. The dynamic performance of the high-speed switch valve determines the speed range and variable dynamic performance that the digital piston can achieve. At present, the high-frequency control of the high-speed switch valve in the digital piston is mostly controlled by multi-voltage. Although the control is simple and efficient, this type of control method cannot adjust the dynamic performance of the high-speed switch. When the speed of the hydraulic pump is high, the piston speed inside the cavity is relatively large. The high-speed switch valve will be subjected to strong pressure shocks during rapid opening and closing, generating huge noise and causing damage to parts such as the piston and the high-speed switch valve. Therefore, the present invention seeks a control method that can adjust the dynamic characteristics of the high-speed switch valve according to the piston speed, taking into account the efficiency of the digital piston while adjusting the opening and closing speed of the digital switch valve within a certain range, thereby greatly reducing the pressure shock inside the chamber. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a digital piston capable of adjusting dynamic characteristics and pressure shock and a control method thereof. The technical solution of the present invention is as follows:

[0006] The present invention first provides a digital piston with adjustable dynamic characteristics and pressure impact, which includes a duty cycle controller, a voltage source group, a first high-speed switch valve, a second high-speed switch valve, a piston, a displacement sensing system, a pressure sensing system, a speed closed-loop controller and a controller;

[0007] The first high-speed switch valve is connected to the oil discharge port of the piston, and the second high-speed switch valve is connected to the oil suction port of the piston; the displacement sensing system and the pressure sensing system obtain the movement state of the piston and the pressure state in the piston cavity in real time; the controller is respectively connected to the displacement sensing system and the pressure sensing system to obtain the information of the movement state of the piston and the pressure state in the cavity; the output port of the controller is connected to the duty cycle controller to control the duty cycle required for its output, the voltage source group includes two voltage sources, wherein the first voltage source is connected to the coil of the first high-speed switch valve, and the second voltage source is connected to the coil of the second high-speed switch valve, the duty cycle controller has two output ports, which are respectively connected to the two voltage sources, and can independently output the required duty cycle to the two voltage sources at the same time, and the speed closed-loop controller is connected to the controller.

[0008] The present invention also provides a control method for the digital piston with adjustable dynamic characteristics and pressure shock, wherein a working cycle of the digital piston is divided into two stages: oil discharge and oil suction; in the oil discharge stage, the first high-speed switch valve is opened and the second high-speed switch valve is closed; in the oil suction stage, the second high-speed switch valve is opened and the first high-speed switch valve is closed;

[0009] A complete working cycle of the first high-speed switch valve and the second high-speed switch valve is divided into a pre-opening stage, an opening stage, an opening maintenance stage, a closing stage and a closing maintenance stage; each stage is realized by the controller controlling the voltage source group to output a voltage with a corresponding duty cycle through a duty cycle controller;

[0010] The control method is specifically as follows:

[0011] When the digital piston needs to discharge oil to the load, the controller controls the duty cycle controller to output a closing duty cycle to the second voltage source, and the second voltage source outputs a closing voltage to control the second high-speed switch valve connected to the piston oil suction port to close; the controller controls the duty cycle controller to output an opening duty cycle to the first voltage source, and the first voltage source outputs an opening voltage to control the first high-speed switch valve connected to the piston oil discharge port to open; then the piston starts to discharge oil to the load;

[0012] During the oil discharge phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is greater than the set threshold speed V drain , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time. The speed closed-loop controller takes the piston speed as input and the opening duty cycle of the first voltage source as output; the controller controls the duty cycle controller to output a lower opening duty cycle to the first voltage source, thereby obtaining a lower opening drive voltage, so that the start-up time of the first high-speed switch valve becomes longer, the dynamic performance is weakened, the speed of the digital piston discharging oil is slowed down, and the pressure impact of the high-speed opening of the first high-speed switch valve on the cavity is reduced; if the piston movement speed is less than the set threshold value V drainWhen the dynamic characteristics of the first high-speed switch valve are not adjusted;

[0013] When the digital piston enters the oil suction state, the controller controls the duty cycle controller to output a closing duty cycle to the first voltage source, and the first voltage source outputs a closing voltage to control the first high-speed switch valve connected to the piston oil discharge port to close. The controller controls the duty cycle controller to output an opening duty cycle to the second voltage source, and the second voltage source outputs an opening voltage to control the second high-speed switch valve connected to the piston oil suction port to open, and the piston sucks oil;

[0014] During the oil suction phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is detected to be less than the set threshold speed V draw , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time. The speed closed-loop controller takes the piston speed as input and the opening duty cycle of the second voltage source as output. The controller controls the duty cycle controller to output the opening duty cycle to the second voltage source to obtain a higher opening drive voltage, so that the start-up time of the second high-speed switch valve becomes shorter, the dynamic performance is enhanced, the speed of the digital piston sucking oil is accelerated, and the filling efficiency of the digital piston is improved; if the piston movement speed is greater than the set threshold speed V draw When the second high-speed switching valve has the same dynamic characteristics as the second high-speed switching valve, the dynamic characteristics of the second high-speed switching valve are not adjusted.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects:

[0016] 1. By changing the duty cycle of the control voltage signal, the equivalent driving voltage of the high-speed switch valve can be changed, and the control is simple and effective. And by adjusting the opening duty cycle and the closing duty cycle, the dynamic performance of the high-speed switch valve can be adjusted.

[0017] 2. The opening duty cycle and closing duty cycle can be adjusted according to the current movement speed of the piston, so that the movement state of the high-speed switch valve can be adjusted along with the movement state of the piston. Users can also set and adjust parameters according to their actual needs. By changing the duty cycle of the control voltage signal, the dynamic characteristics of the high-speed switch valve can be adjusted within a certain range.

[0018] 3. When the piston enters the oil discharge movement state and its movement speed is fast, the dynamic characteristics of the high-speed switch valve can be adjusted to slow down its opening and closing, thereby reducing the pressure impact on the cavity caused by the high-speed opening of the high-speed switch valve when the piston moves at high speed, and reducing damage to the piston, high-speed switch valve and other components.

[0019] 4. When the piston enters the oil suction movement state and its movement speed is slow, the dynamic characteristics of the high-speed switch valve can be adjusted to make it open and close faster, which can greatly enhance the efficiency and flow response characteristics of the digital piston and greatly reduce the time for the digital pump to suck and discharge oil.

[0020] 5. When the digital piston needs to quickly switch between oil discharge and oil suction states, regardless of the piston movement state, the dynamic characteristics of the high-speed switching valve can be improved to improve the efficiency of the digital piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of the present invention;

[0022] Figure 2 Schematic diagram of voltage for a single working cycle of a high-speed switching valve;

[0023] Figure 3 Schematic diagram of the digital piston speed cycle;

[0024] Figure 4 Schematic diagram of digital piston oil discharge status;

[0025] Figure 5 The piston speed is V 2 The dynamic characteristics and piston chamber pressure curve of the high-speed switching valve using this solution;

[0026] Figure 6 The piston speed is V 2 Dynamic characteristics and piston chamber pressure curve of high-speed switching valve with multi-voltage in general scheme;

[0027] Figure 7 Schematic diagram of the digital piston oil suction status;

[0028] Figure 8 The piston speed is V 1 The dynamic characteristics of the high-speed switching valve and the piston chamber flow velocity curve of the present solution are shown;

[0029] Fig. 9 The piston speed is V 1 Dynamic characteristics of high-speed switching valve and piston chamber flow velocity curve using multiple voltages. DETAILED DESCRIPTION

[0030] The present invention is further described and illustrated below in conjunction with specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0031] like Figure 1 As shown, this embodiment includes a duty cycle controller 1, a voltage source group 2, a first high-speed switch valve 3, a second high-speed switch valve 4, a piston 5, a displacement sensor system 6, a pressure sensor system 7, a speed closed-loop controller 8 and a controller 10;

[0032] The first high-speed switch valve 3 is connected to the oil discharge port of the piston 5, and the second high-speed switch valve 4 is connected to the oil suction port of the piston 5; the displacement sensing system 6 and the pressure sensing system 7 obtain the movement state of the piston and the pressure state in the piston cavity in real time; the controller 10 is respectively connected to the displacement sensing system 6 and the pressure sensing system 7 to obtain the information of the movement state of the piston and the pressure state in the cavity; the output port of the controller 10 is connected to the duty cycle controller 1 to control the duty cycle required for its output, and the voltage source group includes two voltage sources, wherein the first voltage source 2-1 is connected to the coil of the first high-speed switch valve 3, and the second voltage source 2-2 is connected to the coil of the second high-speed switch valve 4, and the duty cycle controller 1 has two output ports, which are respectively connected to the two voltage sources, and can independently output the required duty cycle to the two voltage sources at the same time; the speed closed-loop controller 8 is connected to the controller 10, obtains the piston movement speed from the controller 10, and outputs the control duty cycle of the corresponding voltage source to the controller 10, which is sent by the controller 10 to the duty cycle controller 1 to output the duty cycle to the corresponding voltage source. Figure 1 In the embodiment, the control signal 9 is a periodic signal, which is a square wave signal in this embodiment. The controller performs different stages of control according to the rising edge and falling edge of the control signal 9, and finally realizes the control of the digital piston.

[0033] The voltage of a single working cycle of a high-speed switching valve is Figure 2 As shown, it is divided into 5 stages, represented by ①-⑤ respectively. Among them, ① represents the pre-opening stage, which can greatly reduce the opening lag time and facilitate quick entry into the opening stage, ② represents the opening stage, ③ represents the opening maintenance stage, ④ represents the closing stage, and ⑤ represents the closing maintenance stage. The end time of stage ① coincides with the rising edge of the control signal, and the start time of stage ④ coincides with the falling edge of the control signal. The dynamic characteristics of the high-speed switch valve can be adjusted by adjusting the duty cycle output by the duty cycle controller 1. When the first high-speed switch valve 3 is in the opening stage, the second high-speed switch valve 4 is in the closing maintenance stage, and when the second high-speed switch valve 4 is in the opening stage, the first high-speed switch valve 3 is in the closing maintenance stage.

[0034] Digital piston speed cycle such as Figure 3 As shown in the figure, its working state is divided into two cycles: oil discharge and oil suction. When the speed of the piston reaches a very high value, the opening and closing of the high-speed switch valve will cause a strong pressure shock in the chamber, causing damage to the piston and other related components. Therefore, it is necessary to adjust the dynamic performance of the high-speed switch valve according to the movement speed of the digital piston. 1 and high-speed V 2 For example, users can also adjust according to their own needs. In this embodiment, the V drain It is 70% of the maximum speed of the piston. draw 30% of the maximum speed of the piston, V1 Less than the set threshold V drain , V 2 Above the set threshold V drain .

[0035] like Figure 4 As shown, when the digital piston needs to discharge oil to the load, the controller 10 controls the duty cycle controller 1 to output the closing duty cycle to the second voltage source, and the second voltage source 2-2 outputs the closing voltage to control the second high-speed switch valve 4 connected to the oil suction port of the piston 5 to close; the controller 10 controls the duty cycle controller 1 to output the opening duty cycle to the first voltage source, and the first voltage source 2-1 outputs the opening voltage to control the first high-speed switch valve 3 connected to the oil discharge port of the piston 5 to open; then the piston starts to discharge oil to the load;

[0036] During the oil discharge phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is greater than the set threshold speed V drain , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time, and the speed closed-loop controller takes the piston speed as input and the opening duty cycle of the first voltage source as output; the controller 10 controls the duty cycle controller 1 to output a lower opening duty cycle to the first voltage source, and obtains a lower opening drive voltage, so that the start-up time of the first high-speed switch valve 3 becomes longer, the dynamic performance is weakened, the speed of the digital piston discharging oil is slowed down, and the pressure impact caused by the high-speed opening of the first high-speed switch valve on the cavity is reduced; if the piston movement speed is less than the set threshold value V drain When the dynamic characteristics of the first high-speed switch valve are not adjusted;

[0037] Figure 5 and Figure 6 The oil discharge phase is shown respectively, and the piston movement speed is the maximum value V 2 The dynamic characteristics and piston chamber pressure curves of the high-speed switch valve using the present solution and the traditional multi-voltage solution. Comparison of the two shows that the method of the present invention reduces the pressure shock during oil discharge from 16MPa to 14MPa, and increases the full opening time of the switch valve from 2ms to 3ms.

[0038] like Figure 7 As shown, when the digital piston enters the oil suction state, the controller 10 controls the duty cycle controller 1 to output the closing duty cycle to the first voltage source, and the first voltage source 2-1 outputs the closing voltage to control the first high-speed switch valve 3 connected to the oil discharge port of the piston 5 to close, and the controller 10 controls the duty cycle controller 1 to output the opening duty cycle to the second voltage source, and the second voltage source 2-2 outputs the opening voltage to control the second high-speed switch valve 4 connected to the oil suction port of the piston 5 to open, and the piston sucks oil;

[0039] During the oil suction phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is detected to be less than the set threshold speed V draw , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time. The speed closed-loop controller takes the piston speed as input and the opening duty cycle of the second voltage source as output. The controller controls the duty cycle controller to output the opening duty cycle to the second voltage source to obtain a higher opening drive voltage, so that the start-up time of the second high-speed switch valve becomes shorter, the dynamic performance is enhanced, the speed of the digital piston sucking oil is accelerated, and the filling efficiency of the digital piston is improved; if the piston movement speed is greater than the set threshold speed V draw When the second high-speed switching valve has the same dynamic characteristics as the second high-speed switching valve, the dynamic characteristics of the second high-speed switching valve are not adjusted.

[0040] Figure 8 and Fig. 9 The oil suction stage is shown respectively, and the piston movement speed is a small value V 1 The dynamic characteristics and piston chamber pressure curves of the high-speed switch valve using this solution and the traditional multi-voltage solution. Comparison of the two shows that the method of the present invention reduces the time for the piston chamber flow velocity to reach the maximum value during oil suction from 0.015ms to 0.01ms, and shortens the switch valve fully open time from 2ms to 1ms.

[0041] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A control method for a digital piston capable of adjusting dynamic characteristics and pressure shock, the digital piston capable of adjusting dynamic characteristics and pressure shock comprising a duty cycle controller (1), a voltage source group (2), a first high-speed switch valve (3), a second high-speed switch valve (4), a piston (5), a displacement sensing system (6), a pressure sensing system (7), a speed closed-loop controller (8) and a controller (10); The first high-speed switch valve (3) is connected to the oil discharge port of the piston (5), and the second high-speed switch valve (4) is connected to the oil suction port of the piston (5); the displacement sensing system (6) and the pressure sensing system (7) obtain the motion state of the piston and the pressure state in the piston cavity in real time; the controller (10) is respectively connected to the displacement sensing system (6) and the pressure sensing system (7) to obtain information on the motion state of the piston and the pressure state in the cavity; the output port of the controller (10) is connected to the duty cycle controller (1) to control the duty cycle required by the output thereof, the voltage source group comprises two voltage sources, wherein the first voltage source (2-1) is connected to the coil of the first high-speed switch valve (3), and the second voltage source (2-2) is connected to the coil of the second high-speed switch valve (4), and the duty cycle controller (1) has two output ports, which are respectively connected to the two voltage sources, and can independently output the required duty cycle to the two voltage sources at the same time; The speed closed-loop controller (8) is connected to the controller (10); It is characterized in that The control method comprises: One working cycle of the digital piston is divided into two stages: oil discharge and oil suction; in the oil discharge stage, the first high-speed switch valve (3) is opened and the second high-speed switch valve (4) is closed; in the oil suction stage, the second high-speed switch valve (4) is opened and the first high-speed switch valve (3) is closed; A complete working cycle of the first high-speed switch valve (3) and the second high-speed switch valve (4) is divided into a pre-opening stage, an opening stage, an opening maintenance stage, a closing stage and a closing maintenance stage; each stage is achieved by the controller (10) controlling the voltage source group (2) to output a voltage with a corresponding duty cycle through the duty cycle controller (1); The control method is specifically as follows: When the digital piston needs to discharge oil to the load, the controller (10) controls the duty cycle controller (1) to output a closing duty cycle to the second voltage source, and the second voltage source (2-2) outputs a closing voltage to control the second high-speed switch valve (4) connected to the oil suction port of the piston (5) to close; the controller (10) controls the duty cycle controller (1) to output an opening duty cycle to the first voltage source, and the first voltage source (2-1) outputs an opening voltage to control the first high-speed switch valve (3) connected to the oil discharge port of the piston (5) to open; then the piston starts to discharge oil to the load; During the oil discharge phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is greater than the set threshold speed V drain , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time, and the speed closed-loop controller uses the piston speed as input and the opening duty cycle of the first voltage source as output; the controller (10) controls the duty cycle controller (1) to output a lower opening duty cycle to the first voltage source, thereby obtaining a lower opening drive voltage, so that the start-up time of the first high-speed switch valve (3) becomes longer, the dynamic performance is weakened, the speed of the digital piston discharging oil is slowed down, and the pressure impact on the cavity caused by the high-speed opening of the first high-speed switch valve is reduced; if the piston movement speed is less than the set threshold value V drain When the dynamic characteristics of the first high-speed switch valve are not adjusted; When the digital piston enters the oil suction state, the controller (10) controls the duty cycle controller (1) to output a closing duty cycle to the first voltage source, the first voltage source (2-1) outputs a closing voltage to control the first high-speed switch valve (3) connected to the oil discharge port of the piston (5) to close, the controller (10) controls the duty cycle controller (1) to output an opening duty cycle to the second voltage source, the second voltage source (2-2) outputs an opening voltage to control the second high-speed switch valve (4) connected to the oil suction port of the piston (5) to open, and the piston sucks oil; During the oil suction phase, the displacement sensor system detects the piston movement speed in real time. If the piston movement speed is detected to be less than the set threshold speed V draw , the displacement sensing system transmits the movement speed of the piston at this time to the speed closed-loop controller in real time. The speed closed-loop controller takes the piston speed as input and the opening duty cycle of the second voltage source as output. The controller controls the duty cycle controller to output the opening duty cycle to the second voltage source to obtain a higher opening drive voltage, so that the start-up time of the second high-speed switch valve becomes shorter, the dynamic performance is enhanced, the speed of the digital piston sucking oil is accelerated, and the filling efficiency of the digital piston is improved; if the piston movement speed is greater than the set threshold speed V draw When the second high-speed switching valve has the same dynamic characteristics as the second high-speed switching valve, the dynamic characteristics of the second high-speed switching valve are not adjusted.

2. The control method of a digital piston capable of adjusting dynamic characteristics and pressure shock as claimed in claim 1, characterized in that: The V drain It is 70% of the maximum speed of the piston.

3. The control method of a digital piston capable of adjusting dynamic characteristics and pressure shock as claimed in claim 1, characterized in that: The V draw It is 30% of the maximum speed of the piston movement.

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