An experimental platform and test method of a digital variable radial piston pump

Abstract

The application discloses an experimental platform and a testing method of a digital variable radial plunger pump, and relates to the technical field of digital pump experimental testing; the experimental platform comprises a plunger unit, a pressure sensor, an accumulator, a flowmeter, a controller, a host computer and an encoder; the controller comprises a control unit, an encoder interface circuit, a host computer interface circuit, a switch valve driving circuit, a power conversion circuit and an interface circuit module; the experimental platform is designed for researching a new type of digital pump; the experimental platform can obtain the pressure of the plunger cavity of the digital pump in a normal working state and an unloading state in real time, the output flow and flow pulsation of the digital pump, and verifies whether the design of the digital pump meets the expectation; after the controller obtains feedback data, the proportion of the digital code stream is changed, the displacement is corrected, and thus the closed-loop control is completed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital pump experiment test, in particular to an experimental platform and test method of a digital variable radial piston pump. BACKGROUND

[0002] The existing invention patent with the publication number CN109236595A discloses a multi-row multi-acting inner curve rotor driven digital variable radial piston pump, and the publication number CN109139590A discloses an open type digital pump variable displacement flow distribution system based on switching flow distribution and column strategy. The flow distribution system of each piston unit in the digital pump is composed of a two-position two normally closed high-speed on-off valve, an oil suction check valve and an oil discharge check valve. When the piston unit is in a working state, the normally closed high-speed on-off valve is closed, and the oil suction and discharge check valves complete the oil suction and discharge flow distribution function. When it is necessary to place the piston unit in an unloading state, the high-speed on-off valve is driven to open. In a control period, a digital code stream is generated according to the displacement requirement to control the power-on sequence of the high-speed on-off valve, so as to adjust the displacement of the pump.

[0003] This new type of digital pump is in the theoretical stage, and lacks the test platform and the corresponding controller required in the experimental stage. Due to the influence of factors such as pressure, temperature and leakage, there is a difference between the actual displacement obtained by using the previously proposed control strategy and the theoretical displacement. The real-time oil discharge state of the digital pump is not obtained, so that the oil discharge flow is further corrected. The digital pump experimental platform needs to obtain the pressure of the digital pump piston cavity in the normal working state and the unloading state, as well as the output flow and flow pulsation of the digital pump, so as to verify whether the design of the digital pump meets the expectation. The digital pump requires a small size and light weight of the controller, which can set the displacement of the digital pump through the upper computer, and can obtain the pump shaft speed and the displacement of the pump in real time, and adjust the digital code stream of the opening and closing of the valve core of the high-speed on-off valve in time, convert the control signal into the mechanical movement of the valve core of the high-speed on-off valve, so that the output pressure in the pressure range of the digital pump is stable, and the ideal displacement is achieved. Therefore, the corresponding experimental platform and test method are designed for the new type of digital pump. SUMMARY

[0004] The purpose of the present application is to solve the problems raised in the background art, and to provide an experimental platform and test method of a digital variable radial piston pump, which can test the pressure and flow pulsation of the digital variable radial piston pump, and verify whether the design of the pump meets the expectation. At the same time, the controller can realize real-time control of the displacement of the digital variable radial piston pump, so as to obtain more ideal flow distribution characteristics.

[0005] The purpose of the present application can be realized by the following technical solutions:

[0006] In one aspect, the present application provides a new experimental platform of digital variable radial piston pump, including the piston unit of the digital pump, the pressure sensor three, the energy accumulator, the flowmeter one, the flowmeter two, the controller, the host computer and the encoder.

[0007] The digital pump contains several piston units, which include a piston, a pressure sensor one, a normally closed high-speed on-off valve, a pressure sensor two, an oil suction check valve and an oil discharge check valve. The pressure sensor one is inserted into the pump housing until the oil suction pipeline of the pump. The normally closed high-speed on-off valve and the oil suction check valve are connected to the corresponding cavity in the piston unit at one end, and connected to the low-pressure oil tank through the oil suction pipeline and the low-pressure oil suction port of the pump at the other end. The pressure sensor two is inserted into the pump housing until the cavity in the piston unit. The oil discharge check valve is connected to the cavity in the piston unit at one end, and connected to the load circuit through the oil discharge pipeline and the high-pressure oil discharge port of the pump at the other end. The energy accumulator is installed on the load circuit, and the pressure sensor three and the flowmeter two are installed before the energy accumulator and after the high-pressure oil discharge port of the pump. The flowmeter one is installed on the load circuit after the energy accumulator. The controller is connected to the normally closed high-speed on-off valve through the control line, and connected to the pressure sensor one, the pressure sensor two, the pressure sensor three, the flowmeter one, the flowmeter two, the host computer and the encoder through the signal line.

[0008] The controller includes a control unit, an encoder interface circuit, a host computer interface circuit, a switch valve drive circuit, a power conversion circuit and an interface circuit module. The power conversion circuit is connected to the external power supply, the control unit, the switch valve drive circuit, the interface circuit module, the encoder interface circuit and the host computer interface circuit respectively. The control unit is connected to the encoder interface circuit, the host computer interface circuit and the interface circuit module respectively, and is connected to the switch valve drive circuit after photoelectric isolation. The switch valve drive circuit is connected to the normally closed high-speed on-off valve through the control line. The interface circuit module is connected to the pressure sensor one, the pressure sensor two, the pressure sensor three, the flowmeter one and the flowmeter two. The encoder interface circuit is connected to the encoder. The host computer interface circuit is connected to the host computer.

[0009] The power conversion circuit is connected with an external DC 24V power supply, and the power conversion circuit directly supplies 24V voltage DC to the switch valve driving circuit and the interface circuit module in one way, and generates 5V DC after passing through a 24V to 5V circuit to supply the encoder interface circuit and the host computer interface circuit in another way. The generated 5V DC generates -5V DC after passing through a 5V to -5V circuit to supply the interface circuit module in one way, and generates 3.3V DC after passing through a 5V to 3.3V circuit to supply the optoelectronic isolation module and the control unit before the switch valve driving circuit in another way. The 24V to 5V circuit is built with an LM2674MX-5.0 chip, the 5V to -5V circuit is built with an ILC7660 chip, and the 5V to 3.3V circuit is built with an RT9193-33GB chip.

[0010] As a preferred scheme of the application, the control unit adopts an STM32F103RET6 of ST Company as a main chip, and the main chip is provided with multiple ADCs and UART interfaces, so as to meet the requirements of real-time communication with the host computer and system data acquisition.

[0011] The switch valve driving circuit realizes 3.3V control signal driving 24V high-speed switch valve, and this part of circuit is mainly built with a field effect tube IRF540NS and realizes optoelectronic isolation by a photoelectric coupler TLP521.

[0012] The interface circuit module receives 4-20mA analog signals of the sensor, and converts the analog signals into 0-3.3V analog signals that can be received by the control unit, and this part of circuit is mainly built with an operational amplifier LM324.

[0013] As a preferred scheme of the application, the encoder interface circuit converts natural binary RS485 signals of the selected encoder into UART serial data that can be received by the control unit, and pump shaft position information is transmitted to the control unit, and this part of circuit is mainly built with an RS485 protocol chip MAX485ESA of MAXIM Company.

[0014] The host computer interface circuit is connected with the host computer by using a USB, and then a USB interface chip CH341T is adopted to complete protocol conversion from USB to UART, so as to realize real-time communication between the control unit and the host computer, and to set parameters of the control unit.

[0015] On the other hand, the application provides a test method of the digital variable displacement radial piston pump, and the method comprises the following steps:

[0016] The controller receives constant displacement requirements set by the host computer through the host computer interface circuit, and receives pump shaft rotation speed information measured by the encoder through the encoder interface circuit.

[0017] The control unit calculates the displacement of the pump at this time through the pump shaft rotating speed, adjusts the proportion of the output 01 digital code stream, delivers the digital code stream to the switch valve driving circuit, generates a driving current, drives the opening and closing of the high-speed switch valve in the plunger unit, changes the opening and closing proportion of the high-speed switch valve in the plunger cavity of the digital variable radial plunger pump, adjusts the displacement of the digital variable radial plunger pump, and thus realizes open-loop control.

[0018] The controller obtains the pump oil discharge flow and the flow pulsation of the output oil liquid measured by the flow meter two through the interface circuit module, compares the feedback pump oil discharge flow with the constant displacement demand, compensates the previously generated 01 digital code stream when it does not conform to the constant displacement demand, adjusts the opening and closing proportion of the normally closed high-speed switch valve, rebalances the output flow, and completes the control closed loop.

[0019] Compared with the prior art, the beneficial effects of the present application are:

[0020] 1、The experimental platform of the present application is designed for researching a new type of digital pump, and the experimental platform can obtain the pressure of the plunger cavity in the normal working state and the unloaded state of the digital pump, and the output flow and flow pulsation of the digital pump in real time, and verifies whether the design of the digital pump meets the expectation.

[0021] 2、The controller designed in the present application is small in size, light in weight and high in integration. The control unit of the controller obtains the pump shaft rotating speed through the encoder interface circuit, calculates the theoretical displacement of the current pump, sends the digital code stream to make the high-speed switch valve core of the switch valve driving circuit adjust the opening and closing, makes the displacement of the digital pump preliminarily reach the set displacement of the upper computer, realizes open-loop control;

[0022] 3、The pressure sensor obtains the pressure of the plunger cavity in the normal working state and the unloaded state, and the flow meter monitors the output flow and flow pulsation of the digital pump, and feeds back the monitoring displacement information to the controller in real time through the interface circuit module. The controller changes the proportion of the digital code stream after obtaining the feedback data, realizes the correction of the displacement, and thus completes the closed-loop control. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to facilitate the understanding of those skilled in the art, the present application will be further described below with reference to the accompanying drawings.

[0024] Figure 1 is the experimental platform schematic diagram of the novel digital variable radial plunger pump of the present application;

[0025] Figure 2 is the hardware principle schematic diagram of the controller of the present application;

[0026] Figure 3 is the power conversion circuit schematic diagram of the present application;

[0027] Figure 4is a schematic diagram of the control unit of the present application;

[0028] Figure 5 is a schematic diagram of the interface circuit module of the present application;

[0029] Figure 6 is a schematic diagram of the switch valve driving circuit of the present application;

[0030] Figure 7 is a schematic diagram of the host computer interface circuit of the present application;

[0031] Figure 8 is a schematic diagram of the encoder interface circuit of the present application;

[0032] Figure 9 is a workflow diagram of the present application.

[0033] Reference signs: 1, plunger unit; 10, plunger; 11, pressure sensor one; 12, normally closed high-speed switch valve; 13, pressure sensor two; 14, oil suction check valve; 15, oil discharge check valve; 2, pressure sensor three; 3, accumulator; 4, flowmeter one; 5, flowmeter two; 6, controller; 7, host computer; 8, encoder. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described clearly and completely below in conjunction with embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] A novel experimental platform of digital variable radial plunger pump, comprising a plunger unit 1, a pressure sensor three 2, an accumulator 3, a flowmeter one 4, a flowmeter two 5, a controller 6, a host computer 7, and an encoder 8.

[0036] As Figure 1As shown, the digital pump (i.e. digital variable radial piston pump) contains several piston units, the piston unit 1 includes a piston 10, a pressure sensor one 11, a normally closed high-speed on-off valve 12, a pressure sensor two 13, an oil suction check valve 14, an oil discharge check valve 15; the pressure sensor one 11 is inserted into the pump housing until the oil suction pipeline of the pump; the normally closed high-speed on-off valve 12 and the oil suction check valve 14 are respectively connected with the corresponding piston unit 1 cavity, and the other end is connected with the low-pressure oil tank through the oil suction pipeline and the low-pressure oil suction port of the pump; the pressure sensor two 13 is inserted into the pump housing until the cavity in the piston unit 1; the oil discharge check valve 15 valve port one end is connected with the cavity in the piston unit 1, and the other end is connected with the load circuit through the oil discharge pipeline and the high-pressure oil discharge port of the pump; an accumulator 3 is installed on the load circuit, and a pressure sensor three 2 and a flowmeter two 5 are installed before the accumulator 3 and after the high-pressure oil discharge port of the pump; a flowmeter one 4 is installed on the load circuit after the accumulator 3; the controller 6 is connected with the normally closed high-speed on-off valve 12 through the control line, and is connected with the pressure sensor one 11, the pressure sensor two 13, the pressure sensor three 2, the flowmeter one 4, the flowmeter two 5, the upper computer 7 and the encoder 8 through the signal line.

[0037] The displacement of the radial pump is related to the speed of the pump shaft, that is, the higher the speed of the pump shaft, the higher the displacement of the pump. The design of the new digital pump obtains the variable displacement capacity by introducing a high-speed on-off valve, so that the pump can still output constant displacement at different speeds. The piston 10 reciprocates in the piston cavity, and when the piston unit 1 is in an uncontrolled working state, the normally closed high-speed on-off valve 12 is closed, and the oil suction and discharge flow distribution functions are completed by the oil suction and discharge check valves 14 and 15, that is, the oil enters the cavity in the piston unit 1 through the oil suction check valve 14, and is output to the load circuit through the oil discharge check valve 9; when it is needed to place the piston unit 1 in an unloading state, the controller 6 drives the normally closed high-speed on-off valve 12 to open the valve. When the piston 10 enters the oil discharge stroke, due to the high pressure on the load circuit, the oil will be discharged back to the low-pressure oil tank through the normally closed high-speed on-off valve 12, so that no oil is discharged into the load circuit during the oil discharge process of the piston unit 1.

[0038] The pressure sensor two 13 realizes the pressure measurement of the piston cavity. The pressure sensor two 13 respectively obtains the pressure in the piston cavity during the oil suction and discharge process in the uncontrolled working state and the unloading state. The pressure sensor one 11 obtains the pressure of the oil suction pipeline, and then obtains the pressure difference before and after the normally closed high-speed on-off valve 12 and the oil suction check valve 14. The pressure sensor three 2 obtains the pressure of the oil discharge pipeline, and then obtains the pressure difference before and after the oil discharge check valve 15. The controller 6 obtains the pump oil discharge flow through the flowmeter two 5, and obtains the flow pulsation of the output oil. The controller 6 obtains the oil flow output to the load through the flowmeter one 4, and obtains the flow pulsation of the oil after the flow stabilization of the accumulator, and the controller 6 obtains the pump shaft speed information through the encoder 8 installed at the end of the pump shaft.

[0039] AsFigure 2 As shown in the figure, the controller 6 includes a control unit, an encoder interface circuit, a host computer interface circuit, a switch valve drive circuit, a power conversion circuit, an interface circuit module; the power conversion circuit is connected with external power supply, the control unit, the switch valve drive circuit, the interface circuit module, the encoder interface circuit and the host computer interface circuit respectively. The control unit is connected with the encoder interface circuit, the host computer interface circuit and the interface circuit module respectively, and is connected with the switch valve drive circuit after photoelectric isolation. The switch valve drive circuit is connected with the normally closed high-speed switch valve 12 through a control line; the interface circuit module is connected with the pressure sensor one 11, the pressure sensor two 13, the pressure sensor three 2, the flowmeter one 4 and the flowmeter two 5; the encoder interface circuit is connected with the encoder 8; and the host computer interface circuit is connected with the host computer 7.

[0040] As shown in the figure, Figure 3 The power conversion circuit is connected with an external DC 24V power supply, one way of the power conversion circuit directly supplies 24V voltage DC to the switch valve drive circuit and the interface circuit module, and the other way converts 5V DC to the encoder interface circuit and the host computer interface circuit through LM2674MX-5.0. One way of the generated 5V DC converts to-5V DC to supply the interface circuit module through ILC7660 chip, and the other way converts to 3.3V DC to supply the photoelectric isolation module before the switch valve drive circuit and the control unit through RT9193-33GB. RT9193-33GB can generate a maximum of 300mA current, and each photoelectric isolation module before the switch valve drive circuit needs 8mA starting current, so several groups are designed, and other currents are enough for the control unit.

[0041] As shown in the figure, Figure 4 As shown in the figure, the control unit uses STM32F103RET6 of ST company as the main chip, the main chip kernel of which is ARM32 bit Cortex-M3 CPU, the highest working frequency of which is as high as 72MHz, and the control unit adopts low voltage power supply, has multiple ADC and UART interfaces, is used for meeting the real-time communication with the host computer and the system data acquisition requirements, and at the same time, boot starting circuit, clock circuit, reset circuit and decoupling circuit are designed around the main chip.

[0042] As shown in the figure, Figure 5As shown, the interface circuit module converts the 4-20mA current signal into a 0-3.3V voltage signal acceptable by the A / D module of the control unit. The interface circuit module is built by a single power supply four operational amplifier LM324. The input current flows in from the upper end of R78 and flows out from the lower end. The differential amplifier one outputs a voltage U3=U1-U2, and U3 is the voltage difference across the resistor R100, the current flowing through the resistor is 4-20mA, and the voltage generated is 400-2000mV. The voltage divider divides the +5V, and the potentiometer RP1 can adjust U4 to 400mV. After the voltage follower, it becomes U5, U5=U4=400mV. The differential amplifier two is the same as the differential amplifier one, and the output voltage U6=U3-U5. Thus, the input current 4-20mA is converted into 0-1.6V of U6. After the final amplification, U6 is amplified to U7 received by the control unit. Adjusting the potentiometer RP1 can adjust the voltage amplification factor to adjust the range of U7 to 0-3.3V.

[0043] As shown in Figure 6 , the switch valve drive circuit is used to control the 24V high voltage of the high-speed switch valve 12 from the 3.3V low voltage signal of the control unit. The switch valve drive circuit is built by a field effect transistor Q1, and the field effect transistor Q1 uses IRF540NS. When the G voltage of Q1 reaches 10V, it is close to saturation, and the maximum driving current can reach 23A, while the driving current requirement of the high-speed switch valve 12 is 0.6A, which can meet the driving requirement. The power supply voltage of the switch valve drive circuit is 3.3V and 24V. In order to realize electrical isolation, a photoelectric coupler U1 is used, and the photoelectric coupler U1 uses TLP521. The resistor R1 makes the photoelectric coupler U1 obtain a good input current for working state. When the control unit transmits a control signal of 1, that is, a voltage of 3.3V, at this time there is no voltage difference across the light-emitting diode in the photoelectric coupler U1, so there is no current flowing through. When the control unit transmits a control signal of 0, that is, a voltage of 0V, which is divided by R1, at this time the voltage difference across the light-emitting diode in the photoelectric coupler U1 is 1.2V, and there is 8mA current flowing through, the built-in light-emitting diode works, and the photo triode is turned on. D2 is a 10V zener diode, which makes the gate G voltage of the field effect transistor Q1 lower than 10V, close to saturation, and the current flows from the drain D and flows out from the source S, generating a driving current to drive the high-speed switch valve 12 to open. The Schottky diode 1N5819 D1 and the resistor R3 in series play a freewheeling protection role. The light-emitting diode D3 is used for intuitive display of the control signal.

[0044] As shown in Figure 7 , the upper computer interface circuit of the host computer is connected with the host computer by USB, and then the USB interface chip CH341T is used to complete the protocol conversion from USB to UART, realize the real-time communication between the control unit and the host computer 7, and set the parameters of the control unit.

[0045] As shown in Figure 8, the encoder interface circuit converts the natural binary RS485 signal from encoder 8 into UART serial data that can be received by the control unit. This transmits the pump shaft position and speed information to the control unit, which then analyzes the information to determine the plunger position. The encoder interface circuit utilizes the MAX485ESA RS485 protocol chip from MAXIM. Resistor R65 is connected to the A and B bus interfaces to ensure signal matching and prevent reflections.

[0046] The present invention works as follows:

[0047] like Figure 9 As shown, controller 6 receives the constant displacement demand set by host computer 7 via the host computer interface circuit and the pump shaft speed information measured by encoder 8 via the encoder interface circuit. The control unit of controller 6 calculates the current pump displacement based on the pump shaft speed and adjusts the ratio of the output 01 digital code stream. The control unit transmits the digital code stream to the on-off valve drive circuit, generating a drive current that drives the high-speed on-off valve 12 in the plunger unit to open and close, changing the opening and closing ratio of the high-speed on-off valves in the digital pump's several plunger chambers and adjusting the digital pump's displacement, thereby achieving open-loop control. Due to factors such as pressure, temperature, and leakage, there may be errors between the theoretical displacement obtained using open-loop control and the actual displacement. Controller 6 obtains the pump discharge flow rate and the output oil flow pulsation measured by flowmeter 25 via the interface circuit module. The fed-back pump discharge flow rate is compared with the constant displacement demand. If it does not meet the constant displacement demand, the previously generated 01 digital code stream is compensated, the opening and closing ratio of the normally closed high-speed on-off valve is adjusted, and the output flow rate is rebalanced, completing the closed-loop control.

[0048] The control unit can implement various control methods by varying the type of control signal it transmits. Outputting high and low-level signals can achieve sequential control of multiple plunger units. Outputting PWM signals can control valve opening to achieve PWM control, ensuring smoother pump oil delivery. The control unit can also output a control signal in advance, causing the on-off valve drive circuit to open the high-speed on-off valve 12 prematurely to compensate for errors caused by valve core opening delays. The control unit can also implement PID control to ensure the pump's displacement more closely approximates the setpoint.

[0049] From the above structure, the experimental platform of the application is designed for researching new digital pump, the experimental platform can obtain the pressure of the digital pump plunger cavity in normal working state and unloading state, and the output flow and flow pulsation of the digital pump in real time, and verify whether the design of the digital pump meets the expectation; the controller designed by the application has small volume, light weight and high integration; the control unit of the controller obtains the pump shaft rotating speed through the encoder interface circuit, calculates the current pump theoretical displacement, sends digital code stream to make the on-off valve driving circuit adjust the opening and closing of the high-speed on-off valve spool, so that the displacement of the digital pump preliminarily reaches the set displacement of the upper computer, and open-loop control is realized; the pressure of the plunger cavity in normal working state and unloading state is obtained through the pressure sensor, the output flow and flow pulsation of the digital pump are monitored by the flow meter, and the monitoring displacement information is fed back to the controller in real time through the interface circuit module. After the controller obtains the feedback data, the proportion of the digital code stream is changed to realize the correction of the displacement, so that the closed-loop control is completed.

[0050] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, according to the content of the specification, many modifications and changes can be made. The specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that the skilled in the art can well understand and utilize the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. An experimental platform of a digital variable radial piston pump, comprising a plurality of piston units (1), a pressure sensor three (2), an accumulator (3), a flow meter one (4), a flow meter two (5), a controller (6), a host computer (7) and an encoder (8), characterized in that, The plunger unit (1) comprises a plunger (10), a pressure sensor one (11), a normally closed high-speed on-off valve (12), a pressure sensor two (13), an oil suction check valve (14) and an oil discharge check valve (15). The pressure sensor one (11) is inserted into the digital variable radial plunger pump housing until the oil suction pipeline of the digital variable radial plunger pump; one end of the normally closed high-speed on-off valve (12) and the oil suction check valve (14) is connected with the cavity in the plunger unit (1), and the other end is connected with the low-pressure oil tank through the oil suction pipeline and the low-pressure oil suction port of the digital variable radial plunger pump; the pressure sensor two (13) is inserted into the digital variable radial plunger pump housing until the cavity in the plunger unit (1); one end of the oil discharge check valve (15) is connected with the cavity in the plunger unit (1), and the other end is connected with the load circuit through the oil discharge pipeline and the high-pressure oil discharge port of the digital variable radial plunger pump; an accumulator (3) is installed on the load circuit, and a pressure sensor three (2) and a flowmeter two (5) are installed before the accumulator (3) and after the high-pressure oil discharge port of the digital variable radial plunger pump; the flowmeter one (4) is installed on the load circuit after the accumulator (3); the controller (6) is connected with the normally closed high-speed on-off valve (12) through a control line, and is connected with the pressure sensor one (11), the pressure sensor two (13), the pressure sensor three (2), the flowmeter one (4), the flowmeter two (5), an upper computer (7) and an encoder (8) through signal lines; The controller (6) comprises a control unit, an encoder interface circuit, an upper computer interface circuit, a switch valve driving circuit, a power conversion circuit and an interface circuit module.

2. The experimental platform of a digital variable radial piston pump according to claim 1, characterized in that, The power conversion circuit is connected with external power supply, the control unit, the switch valve driving circuit, the interface circuit module, the encoder interface circuit, the upper computer interface circuit respectively; the control unit is connected with the encoder interface circuit, the upper computer interface circuit and the interface circuit module respectively, and is connected with the switch valve driving circuit after photoelectric isolation; the switch valve driving circuit is connected with the normally closed high-speed on-off valve (12) through a control line; the interface circuit module is connected with the pressure sensor one (11), the pressure sensor two (13), the pressure sensor three (2), the flowmeter one (4) and the flowmeter two (5); the encoder interface circuit is connected with the encoder (8); and the upper computer interface circuit is connected with the upper computer (7).

3. The experimental platform of a digital variable-displacement radial piston pump according to claim 2, characterized in that, The control unit is a main chip, which is provided with a plurality of ADCs and UART interfaces, for satisfying real-time communication with the upper computer and system data acquisition.

4. The experimental platform of a digital variable displacement radial piston pump according to claim 1, characterized in that, The switch valve driving circuit is used for realizing low-voltage control signal driving high-voltage high-speed on-off valve, which is built by field effect tubes and realizes photoelectric isolation through photoelectric couplers.

5. The experimental platform of a digital variable-displacement radial piston pump according to claim 4, characterized in that, The interface circuit module is used for receiving analog signals of sensors and converting them into 0-3.3V analog signals that can be received by the control unit, which is built by operational amplifiers.

6. The experimental platform of a digital variable radial piston pump according to claim 5, characterized in that, The encoder interface circuit is used for converting the natural binary RS485 signal of the selected encoder (8) into UART serial data which can be received by the control unit, and the pump shaft position information is thus transmitted to the control unit, and is built by a protocol conversion chip.

7. The experimental platform of a digital variable radial piston pump according to claim 6, characterized in that, The host computer interface circuit is connected with the host computer by USB, and then a USB interface chip is used to complete the protocol conversion from USB to UART, so as to realize the real-time communication between the control unit and the host computer and to set parameters of the control unit.

8. A method of testing a digital variable displacement radial piston pump, characterized by The experimental platform is applied to the digital variable radial piston pump of any one of claims 1-7, and the method comprises: The controller (6) receives the constant displacement demand set by the host computer (7) through the host computer interface circuit and receives the pump shaft speed information measured by the encoder (8) through the encoder interface circuit; The control unit calculates the displacement of the pump at the moment through the pump shaft speed, adjusts the proportion of the output 01 digital code stream, delivers the digital code stream to the on-off valve driving circuit to generate a driving current, drives the high-speed on-off valve (12) in the piston unit (1) to open and close, changes the opening and closing proportion of the high-speed on-off valve (12) in the piston cavity of the digital variable radial piston pump, adjusts the displacement of the digital variable radial piston pump, and thus realizes the open-loop control; The controller (6) obtains the pump oil discharge flow and the flow pulsation of the output oil measured by the flowmeter two (5) through the interface circuit module, compares the feedback pump oil discharge flow with the constant displacement demand, compensates the previously generated 01 digital code stream when the constant displacement demand is not met, adjusts the opening and closing proportion of the normally closed high-speed on-off valve (12), rebalances the output flow, and completes the control closed loop.

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