Digital hydraulic pump controlled by high-speed switch valve bridge

Abstract

The invention discloses a digital hydraulic pump controlled by a high-speed switch valve bridge. The digital hydraulic pump comprises a motor, a swash plate type axial plunger pump, a variable adjusting unit, a pressure compensation unit, a closed-loop control unit, an unloading unit and a filter. The motor is connected with the swash plate type variable displacement piston pump; the variable adjusting unit is connected with the swash plate type variable plunger pump; the pressure compensation unit is connected with the variable adjusting unit to carry out differential pressure compensation on the variable adjusting unit; the closed-loop control unit is connected with the variable adjusting unit and controls the output flow of the variable adjusting unit according to a feedback signal; the high-speed switch valve is subjected to pressure difference compensation through the pressure difference compensator, so that the flow of the high-speed switch valve is not affected by load changes any more, and output pressure fluctuation of the swash plate type variable displacement piston pump is reduced; a high-speed switch valve bridge serves as a pilot level, and digital accurate control over the output pressure of the hydraulic pump is achieved through a closed-loop control unit; the high-speed switch valves are connected in parallel, multi-stage flow output and differential flow control are achieved, and the control precision and the response speed of the digital hydraulic pump are improved.

Description

Technical Field

[0001] The present invention relates to the field of digital hydraulic technology, and particularly to a digital hydraulic pump controlled by a high-speed switching valve bridge. Background Art

[0002] Hydraulic piston pumps have the characteristics of compact structure and high power density, and are widely used in various construction machinery hydraulic transmission systems. Traditional piston pumps use complex mechanical structures to complete functions such as variable displacement control, load-sensing control, power limitation, and pressure cut-off, and have defects such as high manufacturing cost, complex process, inaccurate and inflexible control.

[0003] With the development of mechanical, electrical, and hydraulic control technologies, the market's requirements for the digitalization of piston pumps are also increasing day by day. The variable adjustment unit of the existing digital hydraulic pump is controlled by an electromagnetic proportional valve, and the output flow is changed by controlling the swash plate swing angle. The Chinese patent application with the publication number CN118346591A discloses a programmable digital pump and control method, which adopts this structure. Traditional electromagnetic proportional valves have problems such as slow response speed, low control accuracy, and being relatively sensitive to oil pollution. Compared with traditional electromagnetic proportional valves, high-speed switching valves can directly convert ON / OFF digital signals into flow signals, enabling the direct combination of digital signals and hydraulic systems.

[0004] The output flow of high-speed switching valves is easily affected by load changes, and it cannot meet the demand of hydraulic control technology for stable output flow of digital hydraulic pumps, resulting in limited application scope. The Chinese patent application with the publication number CN108087360A discloses a load port independent control system based on a digital flow valve, which uses high-speed switching valves to control hydraulic cylinders and uses sensors to collect signals for processing by a controller, so as to achieve stable control of the speed of hydraulic cylinders when the load changes. However, this patent does not consider the pressure difference loss of high-speed switching valves when the load changes, which will lead to reduced control accuracy and flow fluctuations. Summary of the Invention

[0005] Aiming at the above-mentioned existing technical deficiencies, the purpose of the present invention is to provide a digital hydraulic pump controlled by a high-speed switching valve bridge, which solves the problem of flow fluctuations caused by pressure difference loss of high-speed switching valves by adding a fixed-differential pressure reducing valve to compensate the pressure difference of high-speed switching valves. In addition, it uses a high-speed switching valve bridge for flow control, and has the advantages of rapid response, high control accuracy, and good controllability. By using the parallel connection method of high-speed switching valves, multi-stage flow control can be realized, and the control accuracy and response speed of the system can be improved.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a digital hydraulic pump controlled by a high-speed switching valve bridge, comprising:

[0008] A power unit, including an electric motor and an inclined-plate axial piston pump driven by the electric motor;

[0009] A variable adjustment unit, including a high-speed switching valve bridge and a variable piston connected by an oil circuit. The high-speed switching valve bridge includes a first high-speed switching valve, a second high-speed switching valve, a third high-speed switching valve, a fourth high-speed switching valve, a fifth high-speed switching valve, and a sixth high-speed switching valve connected in parallel. The high-speed switching valve bridge controls the displacement of the variable piston through the coordinated opening and closing of multiple valves. The piston rod of the variable piston is mechanically connected to the swash plate of the inclined-plate axial piston pump to adjust its inclination angle;

[0010] A pressure compensation unit, including a first fixed-differential pressure reducing valve and a second fixed-differential pressure reducing valve connected to the oil inlet side of the high-speed switching valve bridge. The pressure compensation unit maintains a constant pressure difference across the high-speed switching valve group by dynamically adjusting the pressure in the spring chambers of the first fixed-differential pressure reducing valve and the second fixed-differential pressure reducing valve;

[0011] A closed-loop control unit, including a controller, an angle sensor for detecting the swash plate inclination angle, a pressure sensor for detecting the outlet pressure of the inclined-plate axial piston pump, an LVDT displacement sensor for detecting the displacement of the variable piston, and a comparator, which are electrically connected. The controller generates control instructions for the high-speed switching valve bridge based on the sensor feedback signals; the closed-loop control unit generates PWM modulation signals to drive the combined actions of each high-speed switching valve by real-time collecting signals of the swash plate inclination angle, output pressure, flow rate, and variable piston displacement;

[0012] A unloading unit, including an overflow valve connected to the main oil circuit and a unloading valve controlled by the controller;

[0013] An oil return filtering unit, including a filter connected to the oil return port of the high-speed switching valve bridge.

[0014] Preferably, in the high-speed switching valve bridge, the first high-speed switching valve and the second high-speed switching valve are connected in parallel and then connected to the rod chamber of the variable piston. The third high-speed switching valve and the fourth high-speed switching valve are connected in parallel and then connected to the non-rod chamber of the variable piston;

[0015] The fifth high-speed switching valve is connected to the oil return circuit of the rod chamber of the variable piston, and the sixth high-speed switching valve is connected to the oil return circuit of the non-rod chamber of the variable piston.

[0016] Preferably, the functional implementation method of the pressure compensation unit is as follows:

[0017] The oil inlet of the first fixed-differential pressure reducing valve is connected to the main oil circuit P port of the inclined-plate axial piston pump. The oil outlet of the first fixed-differential pressure reducing valve is divided into two paths: one path is connected to the parallel oil inlet of the third high-speed switching valve and the fourth high-speed switching valve, and the other path is fed back to the non-spring chamber of the first fixed-differential pressure reducing valve; the oil outlet after the parallel connection of the third high-speed switching valve and the fourth high-speed switching valve is connected to the spring chamber of the first fixed-differential pressure reducing valve to form a pressure difference closed-loop compensation;

[0018] The second fixed differential pressure reducing valve is connected to the parallel valve group of the first high-speed switching valve and the second high-speed switching valve in the same way.

[0019] Preferably, the functional implementation mode of the closed-loop control unit includes:

[0020] The controller receives the actual pressure signal from the pressure sensor, compares it with the preset target pressure to generate a deviation signal;

[0021] The controller calculates the duty cycle according to the deviation signal, and sends a PWM command to the high-speed switching valve bridge through an amplifier;

[0022] The controller real-time corrects the displacement of the variable piston and the tilt angle of the swash plate through the LVDT displacement sensor and the angle sensor, forming a multi-parameter closed-loop control of pressure-displacement-angle.

[0023] Preferably, the working modes of the high-speed switching valve bridge include:

[0024] Single-valve oil supply mode: The first high-speed switching valve or the second high-speed switching valve is opened separately, the sixth high-speed switching valve is opened, and the rest of the valves are closed. The oil enters the rodless cavity of the variable piston to reduce the output pressure;

[0025] Dual-valve oil supply mode: The first high-speed switching valve and the second high-speed switching valve are opened simultaneously, the sixth high-speed switching valve is opened, and the rest of the valves are closed. The oil quickly enters the rodless cavity of the variable piston to achieve rapid pressure regulation.

[0026] Differential control mode: The first high-speed switching valve to the fourth high-speed switching valve are synchronously opened to form a differential circuit;

[0027] Emergency unloading mode: Hierarchical pressure protection is achieved through the independently set unloading valve and overflow valve.

[0028] Preferably, the high-speed switching valve bridge is configured in the differential control mode:

[0029] The first high-speed switching valve, the second high-speed switching valve, the third high-speed switching valve, and the fourth high-speed switching valve are opened simultaneously to form a differential oil circuit on both sides of the variable piston. The fifth high-speed switching valve and the sixth high-speed switching valve are closed. The rodless cavity and the rod cavity of the variable piston are filled with oil simultaneously to form a differential connection; At this time, the effective acting area of the variable piston is the difference between the rodless cavity area and the rod cavity area, realizing precise fine adjustment of the swash plate tilt angle;

[0030] The controller precisely controls the displacement of the variable piston and the tilt angle of the swash plate by adjusting the duty cycles of the first high-speed switching valve, the second high-speed switching valve, the third high-speed switching valve, and the fourth high-speed switching valve.

[0031] The controller has an adaptive learning function and optimizes the PWM control parameters according to the historical operating condition data.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. Improvement in differential pressure stability: A fixed-differential pressure reducing valve is used to compensate the differential pressure of the high-speed switching valve, ensuring that the differential pressure at both ends of the high-speed switching valve remains unchanged, making the output flow rate unaffected by the load, reducing the flow rate fluctuation, and improving the stability of the output pressure of the digital hydraulic pump; the fixed-differential pressure reducing valve makes the differential pressure fluctuation of the high-speed switching valve small, greatly reducing the flow rate fluctuation.

[0034] 2. Optimization of response speed: The small response time of the high-speed switching valve combined with the dual-valve parallel oil supply mode results in a relatively large increase in the swashplate swing angle adjustment speed compared with the traditional scheme.

[0035] 3. Enhancement of control accuracy: A closed-loop control unit is introduced to digitally control the output flow rate of the high-speed switching valve bridge, and the high-speed switching valve bridge is used to directly control the variable piston, thereby controlling the output pressure of the digital hydraulic pump, solving the problems of slow response speed and low control accuracy; in the differential mode, the swashplate inclination adjustment has a high resolution and a small output pressure control error.

[0036] 4. Anti-pollution ability: The structure of the high-speed switching valve bridge simplifies the oil circuit, reduces precision mating parts, and reduces the dependence on the cleanliness of the oil.

[0037] 5. Multi-mode compatibility: Supports rapid unloading, precise fine-tuning, and overload protection, adapting to the requirements of complex working conditions. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0039] Figure 1 It is a hydraulic schematic diagram of a digital hydraulic pump controlled by a high-speed switching valve bridge provided by an embodiment of the present invention;

[0040] Figure 2 It is a control schematic diagram of a digital hydraulic pump controlled by a high-speed switching valve bridge provided by an embodiment of the present invention.

[0041] Explanation of the reference numerals in the drawings:

[0042] 1. Motor; 2. Swash plate axial piston pump; 3-1. First high-speed switching valve; 3-2. Second high-speed switching valve; 3-3. Third high-speed switching valve; 3-4. Fourth high-speed switching valve; 3-5. Fifth high-speed switching valve; 3-6. Sixth high-speed switching valve; 3-7. Variable piston; 4-1. First fixed differential pressure reducing valve; 4-2. Second fixed differential pressure reducing valve; 5-1. Controller; 5-2. Amplifier; 5-3. Angle sensor; 5-4. Pressure sensor; 5-5. Flow sensor; 5-6. LVDT displacement sensor; 6-1. Relief valve; 6-2. Unloading valve; 7. Filter; 8. Comparator; 9. Swash plate. Detailed implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] As Figure 1 shown, a digital hydraulic pump controlled by a high-speed switching valve bridge includes:

[0045] A power unit, including a motor 1 and a swash plate axial piston pump 2 driven by it;

[0046] A variable adjustment unit, including a high-speed switching valve bridge and a variable piston 3-7 connected by an oil circuit. The high-speed switching valve bridge includes a parallel valve group composed of a first high-speed switching valve 3-1, a second high-speed switching valve 3-2, a third high-speed switching valve 3-3, a fourth high-speed switching valve 3-4, a fifth high-speed switching valve 3-5, and a sixth high-speed switching valve 3-6 in parallel. The high-speed switching valve bridge controls the displacement of the variable piston 3-7 through the coordinated opening and closing of multiple valves. The piston rod of the variable piston 3-7 is mechanically connected to the swash plate 9 of the swash plate axial piston pump 2 to adjust its inclination angle;

[0047] A pressure compensation unit, including a first fixed differential pressure reducing valve 4-1 and a second fixed differential pressure reducing valve 4-2 connected to the inlet side of the high-speed switching valve bridge. The pressure compensation unit maintains a constant pressure difference across the high-speed switching valve group by dynamically adjusting the pressure in the spring chambers of the first fixed differential pressure reducing valve 4-1 and the second fixed differential pressure reducing valve 4-2;

[0048] The closed-loop control unit includes a controller 5-1, an angle sensor 5-3 for detecting the inclination angle of the swash plate 9, a pressure sensor 5-4 for detecting the outlet pressure of the swash plate axial piston pump 2, and an LVDT displacement sensor 5-6 for detecting the displacement of the variable piston 3-7. The controller 5-1 generates control instructions for the high-speed switching valve bridge based on the sensor feedback signals. The closed-loop control unit collects the signals of the inclination angle of the swash plate 9, the output pressure, the flow rate, and the displacement of the variable piston 3-7 in real time, and generates PWM modulation signals through a closed-loop control algorithm to drive the combined actions of each high-speed switching valve.

[0049] The unloading unit includes an overflow valve 6-1 connected to the main oil circuit and an unloading valve 6-2 controlled by the controller 5-1.

[0050] The oil return filtering unit includes a filter 7 connected to the oil return port of the high-speed switching valve bridge.

[0051] The digital hydraulic pump controlled by the high-speed switching valve bridge provided in this embodiment has the following basic working principle: When the system is working, the motor 1 drives the swash plate axial piston pump 2 to complete the oil suction and discharge process. When the system load changes, the angle sensor 5-3 and the pressure sensor 5-4 sample the data and convert the obtained pressure signal and angle signal into electrical signals and transmit them to the controller 5-1. The controller 5-1 compares the obtained electrical signals with the set signals, obtains a deviation signal through the comparison, corrects the deviation signal and converts it into a required duty cycle signal. After being amplified by the amplifier 5-2, it is transmitted to the first high-speed switching valve 3-1, the second high-speed switching valve 3-2, the third high-speed switching valve 3-3, the fourth high-speed switching valve 3-4, the fifth high-speed switching valve 3-5, and the sixth high-speed switching valve 3-6. The opening and closing states of different high-speed switching valves can be selected according to different working conditions.

[0052] Optionally, the working modes include:

[0053] Working mode 1: When one of the first high-speed switching valve 3-1 and the second high-speed switching valve 3-2 is opened and the other is closed, and the sixth high-speed switching valve 3-6 is opened while the rest of the high-speed switching valves are closed, the oil enters the rod chamber of the variable piston 3-7, the swash plate swing angle of the swash plate axial piston pump 2 decreases, and the output pressure of the swash plate axial piston pump 2 decreases.

[0054] Working mode 2: When the first high-speed switching valve 3-1 is opened, the second high-speed switching valve 3-2 is opened, and the sixth high-speed switching valve 3-6 is opened while the rest of the high-speed switching valves are closed. At this time, the two valves supply oil to the variable piston 3-7, the oil enters the rod chamber of the variable piston 3-7, the swash plate 9 swing angle of the swash plate axial piston pump 2 decreases rapidly, and the output pressure of the swash plate axial piston pump 2 decreases rapidly.

[0055] Working mode three: When one of the third high-speed switching valve 3-3 and the fourth high-speed switching valve 3-4 is open and the other is closed, and the fifth high-speed switching valve 3-5 is open while the rest of the high-speed switching valves are closed, the hydraulic oil enters the rodless cavity of the variable piston, the swash plate angle of the swash plate type axial piston pump 2 increases, and the output pressure of the swash plate type axial piston pump 2 increases;

[0056] Working mode four: When the third high-speed switching valve 3-3 is open, the fourth high-speed switching valve 3-4 is open, and the fifth high-speed switching valve 3-5 is open while the rest of the high-speed switching valves are closed, at this time, oil is supplied to the double-valve variable piston 3-7. The hydraulic oil enters the rodless cavity of the variable piston 3-7, the swash plate angle of the swash plate type axial piston pump 2 increases rapidly, and the output pressure of the swash plate type axial piston pump 2 increases rapidly;

[0057] When working mode five: When the first high-speed switching valve 3-1, the second high-speed switching valve 3-2, the third high-speed switching valve 3-3, and the fourth high-speed switching valve 3-4 are all open, and the fifth high-speed switching valve 3-5 and the sixth high-speed switching valve 3-6 are closed, the variable piston 3-7 is in a differential connection state, and the differential connection state can be used to precisely control the output pressure.

[0058] The first fixed differential pressure reducing valve 4-1 compensates the pressure difference of the parallel valve of the third high-speed switching valve 3-3 and the fourth high-speed switching valve 3-4, so that the flow rate of the parallel valve of the third high-speed switching valve 3-3 and the fourth high-speed switching valve 3-4 is no longer affected by the load change. The second fixed differential pressure reducing valve 4-2 compensates the pressure difference of the parallel valve of the first high-speed switching valve 3-1 and the second high-speed switching valve 3-2, so that the flow rate of the parallel valve of the first high-speed switching valve 3-1 and the second high-speed switching valve 3-2 is no longer affected by the load change.

[0059] The parallel valve of the first high-speed switching valve 3-1 and the second high-speed switching valve 3-2 is connected to the rod chamber of the variable piston. At this time, the hydraulic oil discharged from the rodless cavity of the variable piston 3-7 returns to the fuel tank through the sixth high-speed switching valve 3-6 via the filter 7, and transmits a signal to the controller 5-1 through the flow sensor 5-5. The parallel valve of the third high-speed switching valve 3-3 and the fourth high-speed switching valve 3-4 is connected to the rodless cavity of the variable piston 3-7. At this time, the hydraulic oil discharged from the rod chamber of the variable piston 3-7 returns to the fuel tank through the fifth high-speed switching valve 3-5 via the filter 7, and transmits a signal to the controller 5-1 through the flow sensor 5-5.

[0060] When the system needs to unload, the controller 5-1 sends a signal, which is transmitted to the unloading valve 6-2 through the amplifier 5-2 to open the unloading valve 6-2, and the system unloads. When the system pressure is too high, the hydraulic oil flows into the fuel tank through the overflow valve 6-1, and the system unloads.

[0061] Such as Figure 2As shown in the figure, it is a control schematic diagram of a digital hydraulic pump controlled by a high-speed switching valve bridge, including a swashplate axial piston pump 2, a first high-speed switching valve 3-1, a second high-speed switching valve 3-2, a third high-speed switching valve 3-3, a fourth high-speed switching valve 3-4, a fifth high-speed switching valve 3-5, a sixth high-speed switching valve 3-6, a variable piston 3-7, a controller 5-1, an amplifier 5-2, a flow sensor 5-5, an LVDT displacement sensor 5-6, an angle sensor 5-3, a pressure sensor 5-4, a comparator 8, and a swashplate 9.

[0062] The basic working principle of this control system is as follows: The target pressure signal of the present invention is given by the user, and the target signal is transmitted to the controller 5-1. The controller processes the signal and transmits it to the amplifier 5-2. According to different specific working conditions, the amplifier 5-2 sends pulse command signals to different high-speed switching valves.

[0063] When the load pressure decreases, one of the first high-speed switching valve 3-1 and the second high-speed switching valve 3-2 receives the pulse command signal and opens, and the other closes. The sixth high-speed switching valve 3-6 receives the pulse command signal and opens, and the remaining high-speed switching valves close. The oil enters the rod chamber of the variable piston 3-7, the swashplate angle of the swashplate axial piston pump 2 decreases, and the output pressure of the swashplate axial piston pump 2 decreases. At this time, the oil in the rodless chamber of the variable piston 3-7 returns to the fuel tank through the filter 7, and transmits the signal to the controller through the flow sensor 5-5. The displacement signal of the piston rod of the variable piston 3-7 is transmitted to the controller 5-1 through the LVDT displacement sensor 5-6, the inclination angle signal of the swashplate 9 is transmitted to the controller 5-1 through the angle sensor 5-3, and the output pressure of the swashplate axial piston pump 2 is transmitted to the comparator 8 through the pressure sensor 5-4. The comparator 8 is electrically connected to the controller.

[0064] When the load pressure decreases rapidly, the first high-speed switching valve 3-1 receives the pulse command signal and opens, the second high-speed switching valve 3-2 receives the pulse command signal and opens, the sixth high-speed switching valve 3-6 receives the pulse command signal and opens, and the remaining high-speed switching valves close. At this time, the double valve supplies oil to the variable piston 3-7. The oil enters the rod chamber of the variable piston 3-7, the swashplate angle of the swashplate axial piston pump 2 decreases rapidly, and the output pressure of the swashplate axial piston pump 2 decreases rapidly. At this time, the oil in the rodless chamber of the variable piston 3-7 returns to the fuel tank through the filter 7, and transmits the signal to the controller through the flow sensor 5-5. The displacement signal of the piston rod of the variable piston 3-7 is transmitted to the controller 5-1 through the LVDT displacement sensor 5-6, and the inclination angle signal of the swashplate 9 is transmitted to the controller 5-1 through the angle sensor 5-3. The output pressure of the swashplate axial piston pump 2 is transmitted to the comparator 8 through the pressure sensor 5-4.

[0065] When the load pressure increases, one of the third high-speed switching valve 3-3 and the fourth high-speed switching valve 3-4 receives a pulse command signal to open, and the other closes. The fifth high-speed switching valve 3-5 receives a pulse command signal to open, and the remaining high-speed switching valves close. The oil enters the rodless cavity of the variable piston 3-7, the swashplate angle of the swashplate type axial piston pump 2 increases, and the output pressure of the swashplate type axial piston pump 2 increases. At this time, the oil in the rod cavity of the variable piston 3-7 returns to the fuel tank through the filter 7, and the signal is transmitted to the controller 5-1 through the flow sensor 5-5. The displacement signal of the piston rod of the variable piston 3-7 is transmitted to the controller 5-1 through the LVDT displacement sensor 5-6, the inclination angle signal of the swashplate 9 is transmitted to the controller 5-1 through the angle sensor 5-3, and the output pressure of the swashplate type axial piston pump 2 is transmitted to the comparator 8 through the pressure sensor 5-4.

[0066] When the load pressure increases rapidly, the third high-speed switching valve 3-3 receives a pulse command signal to open, the fourth high-speed switching valve 3-4 receives a pulse command signal to open, the fifth high-speed switching valve 3-5 receives a pulse command signal to open, and the remaining high-speed switching valves close. At this time, the two valves supply oil to the variable piston 3-7. The oil enters the rodless cavity of the variable piston 3-7, the swashplate angle of the swashplate type axial piston pump 2 increases rapidly, and the output pressure of the swashplate type axial piston pump 2 increases rapidly. At this time, the oil in the rod cavity of the variable piston 3-7 returns to the fuel tank through the filter 7, and the signal is transmitted to the controller 5-1 through the flow sensor 5-5. The displacement signal of the piston rod of the variable piston 3-7 is transmitted to the controller 5-1 through the LVDT displacement sensor 5-6, the inclination angle signal of the swashplate 9 is transmitted to the controller 5-1 through the angle sensor 5-3, and the output pressure of the swashplate type axial piston pump 2 is transmitted to the comparator 8 through the pressure sensor 5-4.

[0067] When precise control of the load pressure is required, the first high-speed switching valve 3-1, the second high-speed switching valve 3-2, the third high-speed switching valve 3-3, and the fourth high-speed switching valve 3-4 all receive pulse command signals to open, the fifth high-speed switching valve 3-5 and the sixth high-speed switching valve 3-6 receive pulse command signals to close, and the variable piston 3-7 is in a differential connection state. At this time, the oil in the rod cavity of the variable piston 3-7 returns to the fuel tank through the filter 7, and the signal is transmitted to the controller 5-1 through the flow sensor 5-5. The displacement signal of the piston rod of the variable piston 3-7 is transmitted to the controller 5-1 through the LVDT displacement sensor 5-6, the inclination angle signal of the swashplate 9 is transmitted to the controller 5-1 through the angle sensor 5-3, and the output pressure of the swashplate type axial piston pump 2 is transmitted to the comparator 8 through the pressure sensor 5-4. The comparator 8 generates a control deviation by comparing the target signal and the sensor feedback signal in real time, thereby driving the system to achieve closed-loop regulation.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A digital hydraulic pump controlled by a high-speed switch valve bridge, characterized in that: include: A power unit, comprising an electric motor (1) and a swash plate type axial piston pump (2) driven by the electric motor; A variable regulating unit comprises a high-speed switch valve bridge and a variable piston (3-7) connected by an oil circuit, wherein the high-speed switch valve bridge comprises a parallel valve group consisting of a first high-speed switch valve (3-1), a second high-speed switch valve (3-2), a third high-speed switch valve (3-3), a fourth high-speed switch valve (3-4), a fifth high-speed switch valve (3-5) and a sixth high-speed switch valve (3-6) connected in parallel, wherein the high-speed switch valve bridge controls the displacement of the variable piston (3-7) by opening and closing multiple valves in coordination, and a piston rod of the variable piston (3-7) is mechanically connected to a swash plate (9) of a swash plate type axial piston pump (2) to adjust its inclination angle; A pressure compensation unit comprises a first differential pressure reducing valve (4-1) and a second differential pressure reducing valve (4-2) connected to the oil inlet side of the high-speed switching valve bridge, wherein the pressure compensation unit maintains a constant pressure difference at both ends of the high-speed switching valve group by dynamically adjusting the pressure of the spring chambers in the first differential pressure reducing valve (4-1) and the second differential pressure reducing valve (4-2); A closed-loop control unit comprises an electrically connected controller (5-1), an angle sensor (5-3) for detecting the inclination of a swash plate (9), a pressure sensor (5-4) for detecting the outlet pressure of a swash plate type axial piston pump (2), an LVDT displacement sensor (5-6) for detecting the displacement of a variable piston (3-7), and a comparator (8), wherein the controller (5-1) generates a control instruction for a high-speed switch valve bridge based on a sensor feedback signal; the closed-loop control unit generates a PWM modulation signal to drive each high-speed switch valve combination to operate by real-time acquisition of the inclination of the swash plate (9), the output pressure, the flow rate, and the displacement signal of the variable piston (3-7); The unloading unit comprises a relief valve (6-1) connected to the main oil circuit and an unloading valve (6-2) controlled by a controller (5-1); The oil return filter unit comprises a filter (7) connected to the oil return port of the high-speed switching valve bridge.

2. A digital hydraulic pump controlled by a high-speed switch valve bridge as claimed in claim 1, characterized in that: In the high-speed switch valve bridge, the first high-speed switch valve (3-1) and the second high-speed switch valve (3-2) are connected in parallel and then connected to the variable piston (3-7) with a rod cavity, and the third high-speed switch valve (3-3) and the fourth high-speed switch valve (3-4) are connected in parallel and then connected to the variable piston (3-7) without a rod cavity; The fifth high-speed switch valve (3-5) is connected to the oil return path of the rod chamber of the variable piston (3-7), and the sixth high-speed switch valve (3-6) is connected to the oil return path of the rodless chamber of the variable piston (3-7).

3. A digital hydraulic pump controlled by a high-speed switch valve bridge as claimed in claim 2, characterized in that: The function of the pressure compensation unit is realized as follows: The oil inlet of the first differential pressure reducing valve (4-1) is connected to the main oil circuit P port of the swash plate axial piston pump (2), and the oil outlet of the first differential pressure reducing valve (4-1) is divided into two paths: one path is connected to the parallel oil inlet of the third high-speed switch valve (3-3) and the fourth high-speed switch valve (3-4), and the other path is fed back to the non-spring chamber of the first differential pressure reducing valve (4-1); the oil outlet of the third high-speed switch valve (3-3) and the fourth high-speed switch valve (3-4) connected in parallel is connected to the spring chamber of the first differential pressure reducing valve (4-1), forming a pressure differential closed-loop compensation; The second differential pressure reducing valve (4-2) is connected to the parallel valve group of the first high-speed switching valve (3-1) and the second high-speed switching valve (3-2) in the same manner.

4. A digital hydraulic pump controlled by a high-speed switch valve bridge as claimed in claim 3, characterized in that: The functional implementation of the closed-loop control unit includes: The controller (5-1) receives an actual pressure signal from a pressure sensor (5-4), compares the actual pressure signal with a preset target pressure, and generates a deviation signal; The controller (5-1) calculates the duty cycle according to the deviation signal and sends a PWM instruction to the high-speed switch valve bridge through the amplifier (5-2); The controller (5-1) corrects the displacement of the variable piston (3-7) and the inclination angle of the swash plate (9) in real time through an LVDT displacement sensor (5-6) and an angle sensor (5-3), thereby forming a multi-parameter closed-loop control of pressure-displacement-angle.

5. A high-speed switch valve bridge controlled digital hydraulic pump as claimed in claim 4, characterized in that: The working modes of the high-speed switching valve bridge include: Single valve oil supply mode: the first high-speed switch valve (3-1) or the second high-speed switch valve (3-2) is opened alone, the sixth high-speed switch valve (3-6) is opened, and the other valves are closed, and the oil enters the rod chamber of the variable piston (3-7) to reduce the output pressure; Double valve oil supply mode: the first high-speed switch valve (3-1) and the second high-speed switch valve (3-2) are opened at the same time, the sixth high-speed switch valve (3-6) is opened, and the other valves are closed, and the oil quickly enters the rod chamber of the variable piston (3-7) to achieve rapid pressure regulation. Differential control mode: synchronously opening the first high-speed switch valve (3-1) to the fourth high-speed switch valve (3-4) to form a differential loop; Emergency unloading mode: Gradual pressure protection is achieved through independently set unloading valves (6-2) and relief valves (6-1).

6. A high-speed switch valve bridge controlled digital hydraulic pump as claimed in claim 5, characterized in that: The high-speed switching valve bridge is configured in differential control mode: The first high-speed switch valve (3-1), the second high-speed switch valve (3-2), the third high-speed switch valve (3-3) and the fourth high-speed switch valve (3-4) are opened simultaneously to form a differential oil path on both sides of the variable piston (3-7), the fifth high-speed switch valve (3-5) and the sixth high-speed switch valve (3-6) are closed, and the rodless chamber and the rod chamber of the variable piston (3-7) are simultaneously filled with oil to form a differential connection; The controller (5-1) accurately controls the displacement of the variable piston (3-7) and the inclination angle of the swash plate by adjusting the duty ratios of the first high-speed switch valve (3-1), the second high-speed switch valve (3-2), the third high-speed switch valve (3-3) and the fourth high-speed switch valve (3-4).

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