A high-precision hydraulic loading device without an external power source

Abstract

This invention discloses a high-precision hydraulic loading device without an external power source, comprising an accumulator, a high-speed switching valve, a relief valve, a booster cylinder, a displacement sensor, an oil reservoir, a hydraulic cylinder, a pressure sensor, and hydraulic connectors. This device applies the accumulator and booster cylinder to a digital hydraulic system centered on the high-speed switching valve. The accumulator serves as the system's power source, the high-speed switching valve is controlled by pulse-width modulation signals, and the booster cylinder enhances the system's loading capacity and flow output resolution, satisfying the switching and precise pressure control of four pressure control circuits: rapid boosting, precise boosting, rapid depressurization, and precise depressurization. This invention enables hydraulic loading of mechanical testing equipment, and is particularly suitable for working environments without an external power source, such as multi-parameter environmental coupling test chambers. It offers advantages such as low cost, low energy consumption, high integration, high reliability, and high precision.

Description

Technical Field

[0001] This invention relates to the field of hydraulic loading technology, and in particular to a high-precision hydraulic loading device without an external power source. Background Technology

[0002] With the rapid development of science and technology and the continuous advancement of engineering techniques, the performance evaluation of materials, equipment, and systems under complex and variable environmental conditions has become increasingly important. Multi-parameter environmental coupling test chambers can typically simulate various environmental conditions, such as temperature, humidity, pressure, light intensity, radiation, and wind speed. Simultaneously, they can monitor and control these parameters in real time to meet different experimental needs. For example, in fields such as new energy, aerospace, automotive, and electronics, such test chambers can be used to test the performance and reliability of materials and equipment under extreme environments. Hydraulic transmission technology has advantages such as high power density, large output force, high control precision, and ease of achieving linear motion, and is therefore widely used in the field of material and equipment mechanical property testing.

[0003] Traditional hydraulic loading devices require an additional hydraulic pump station, whose operating noise significantly impacts the surrounding environment and testing personnel, occupies a large amount of floor space, and is complex to maintain and operate, with poor convenience in testing. Valves, as core components of hydraulic systems, affect the performance of the entire system. In precision drive hydraulic systems, high-frequency response, high-precision electro-hydraulic servo valves are mostly used. However, due to the constraints of their own structural characteristics, electro-hydraulic servo valves are prone to problems such as zero drift, wear, or jamming under high temperature, high pressure, strong vibration, and electromagnetic interference environments. They also have high requirements for oil cleanliness, making long-term reliability difficult to guarantee. High-speed switching valves are compact, highly resistant to contamination, simple to control, inexpensive, and highly reliable electro-hydraulic digital valves. However, hydraulic systems based on pulse width modulation high-speed switching valves typically suffer from inaccurate flow control and low pressure control precision. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a high-precision hydraulic loading device that requires no external power source.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a high-precision hydraulic loading device without an external power source, the device comprising a hydraulic control unit, a hydraulic execution unit, and a mechanical unit;

[0007] The hydraulic control unit includes an accumulator, a first high-speed switching valve, a first pressure sensor, a second high-speed switching valve, a displacement sensor, a booster cylinder, a third high-speed switching valve, a relief valve, an oil reservoir, a fourth high-speed switching valve, a first hydraulic connector, a first shut-off valve, a second hydraulic connector, and a second shut-off valve. A first pressure sensor is installed at the oil port of the accumulator. The oil inlets of both the first and second high-speed switching valves are connected to the accumulator. The oil outlet of the first high-speed switching valve is connected to the rodless chamber of the booster cylinder, and the oil outlet of the second high-speed switching valve is connected to the rod chamber of the booster cylinder. The booster... The cylinder is equipped with a displacement sensor to detect the piston rod stroke; the oil inlet of the third high-speed switching valve is connected to the rodless chamber of the booster cylinder, and the oil inlet of the fourth high-speed switching valve is connected to the rod chamber of the booster cylinder; an overflow valve is installed on the flow channel between the rod chamber of the booster cylinder and the oil inlet of the fourth high-speed switching valve; the oil outlet of the oil storage tank is connected to the oil outlet of the third high-speed switching valve, the oil outlet of the overflow valve, and the oil outlet of the fourth high-speed switching valve; the first hydraulic connector is connected to the first shut-off valve and to the accumulator for filling the accumulator; the second hydraulic connector is connected to the second shut-off valve and to the oil storage tank for draining the oil storage tank;

[0008] The hydraulic actuator includes a hydraulic hose, a second pressure sensor, and a hydraulic cylinder; the rodless chamber of the hydraulic cylinder is connected to the rod chamber of the booster cylinder via the hydraulic hose, and the second pressure sensor is used to monitor the pressure in the rodless chamber of the hydraulic cylinder.

[0009] The mechanical unit includes a base plate, a first valve block, and a second valve block. The accumulator, the first high-speed switching valve, the first pressure sensor, the second high-speed switching valve, the first hydraulic connector, and the first shut-off valve are all mounted on the first valve block, and all components are connected through the internal flow channels of the valve block. The third high-speed switching valve, the overflow valve, the oil storage tank, the fourth high-speed switching valve, the second hydraulic connector, and the second shut-off valve are all mounted on the second valve block, and all components are connected through the internal flow channels of the valve block. The first valve block, the second valve block, and the booster cylinder are fixed on the base plate. The accumulator housing and the oil storage tank housing are connected and fixed to the booster cylinder.

[0010] The first, second, third, and fourth high-speed switching valves are normally closed two-position two-way valves. The opening and closing of the valve core are controlled by a pulse width modulation signal. When the pulse width modulation signal is high, the electromagnet of the high-speed switching valve is energized and the valve core opens; when the pulse width modulation signal is low, the electromagnet of the high-speed switching valve is de-energized and the valve core resets.

[0011] The hydraulic control unit has four pressure control circuits: When the first high-speed switching valve solenoid is energized, the high-pressure oil from the accumulator flows through the first high-speed switching valve to the rodless chamber of the booster cylinder, the piston rod of the booster cylinder extends, and the oil from the rod chamber of the booster cylinder enters the rodless chamber of the hydraulic cylinder for precise pressure boosting; when the second high-speed switching valve solenoid is energized, the high-pressure oil from the accumulator flows through the second high-speed switching valve and the rod chamber of the booster cylinder directly to the rodless chamber of the hydraulic cylinder for rapid pressure boosting; when the third high-speed switching valve solenoid is energized, the high-pressure oil from the rodless chamber of the hydraulic cylinder flows to the rod chamber of the booster cylinder, the piston rod of the booster cylinder retracts, and the oil from the rodless chamber of the booster cylinder flows back to the oil storage tank through the third high-speed switching valve for precise pressure reduction; when the fourth high-speed switching valve solenoid is energized, the high-pressure oil from the rodless chamber of the hydraulic cylinder flows through the rod chamber of the booster cylinder and the fourth high-speed switching valve directly back to the oil storage tank for rapid pressure reduction.

[0012] Furthermore, the piston rod area of ​​the rod chamber of the booster cylinder is smaller than the piston area of ​​the rodless chamber, the boosting ratio N is the ratio of the piston area of ​​the rodless chamber to the piston rod area of ​​the rod chamber, and the input pressure required for the rodless chamber of the booster cylinder is 1 / N of the actual control pressure value of the rodless chamber of the hydraulic cylinder.

[0013] High-speed on / off valves utilize pulse width modulation (PWM) signal control, which adjusts the duty cycle τ to control the valve's on / off time, thereby achieving real-time flow regulation. The average flow rate of the high-speed on / off valve... It is directly proportional to the pulse width modulation duty cycle τ;

[0014] When the electromagnet of the first high-speed switching valve is energized for precise pressure boosting, the actual input flow rate of the rodless chamber of the hydraulic cylinder is equal to the input flow rate of the rodless chamber of the booster cylinder. The accuracy of system flow and pressure control is further improved by 1 / N;

[0015] When the third high-speed switching valve solenoid is energized for precise pressure reduction, the actual output flow of the rodless chamber of the hydraulic cylinder is the same as the output flow of the rodless chamber of the booster cylinder. With a ratio of 1 / N, the accuracy of system flow and pressure control is also further improved.

[0016] Furthermore, the accumulator is a bladder-type accumulator, and the pre-charged nitrogen volume V at pressure P3 is:

[0017]

[0018] Where ΔV is the volume of oil to be discharged by the accumulator, ΔV = V1N, and V1 is the volume of the rodless chamber at the maximum stroke of the hydraulic cylinder; P min P is the minimum operating pressure for the accumulator. min =P / N, where P is the rated pressure of the rodless chamber of the hydraulic cylinder; P3 is the accumulator charging pressure; P max ρ is the maximum operating pressure of the accumulator; n is the gas state index.

[0019] Furthermore, the average flow rate of the high-speed switching valve It is directly proportional to the pulse width modulation duty cycle τ, as shown in the following formula:

[0020]

[0021] Among them, Q max The output flow rate is when the valve is fully open; the duty cycle τ is the valve core opening time T. p The ratio to the period T; C d A is the valve orifice flow coefficient; m ρ is the maximum flow area at the valve port; ΔP is the valve port pressure difference; and ρ is the hydraulic oil density.

[0022] Furthermore, the pressure change ΔP1 generated per unit time in the rodless chamber of the hydraulic cylinder is:

[0023]

[0024] Where β is the bulk modulus of hydraulic oil; V0 is the volume of the rodless chamber of the hydraulic cylinder.

[0025] Furthermore, the hydraulic control unit is divided into manual control mode and automatic control mode; in the manual control mode, a pulse width modulation signal for the high-speed switching valve can be given separately to perform open-loop control of the pressure in the rodless chamber of the hydraulic cylinder.

[0026] In the automatic control mode, the actuator is a hydraulic cylinder, the detection element is a second pressure sensor, and the control elements are a first high-speed switching valve, a second high-speed switching valve, a third high-speed switching valve, and a fourth high-speed switching valve. Each high-speed switching valve is controlled by an independent pulse width modulation controller. The target pressure value P0 of the hydraulic cylinder is set, and the actual pressure value P1 of the rodless chamber of the hydraulic cylinder is detected by the second pressure sensor, thereby obtaining the deviation signal e = P0 - P1. The control valve switching logic automatically switches the four high-speed switching valves. The pulse width modulation controller processes the deviation signal e input by the system and outputs a pulse width modulation signal, thereby controlling the movement of the valve core of the high-speed switching valve to regulate the output flow until the pressure in the rodless chamber of the hydraulic cylinder reaches the target value P0.

[0027] Furthermore, the control valve switching logic of the hydraulic control unit is determined by the target pressure value P0 of the hydraulic cylinder, the actual pressure value P1 of the rodless chamber of the hydraulic cylinder detected by the second pressure sensor, and the actual pressure value P2 of the accumulator detected by the first pressure sensor.

[0028] When the target pressure value P0 is greater than the actual pressure value P1, and the accumulator pressure value P2 is greater than or equal to a% higher than the actual pressure value P1, and the target pressure value P0 is greater than or equal to b% higher than the actual pressure value P1, switch to the second high-speed switching valve.

[0029] When the target pressure value P0 is greater than the actual pressure value P1, and the accumulator pressure value P2 is not greater than or equal to a% higher than the actual pressure value P1, or the target pressure value P0 is not greater than or equal to b% higher than the actual pressure value P1, switch to the first high-speed switching valve.

[0030] When the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is greater than or equal to c% higher than the target pressure value P0, switch to the fourth high-speed switching valve.

[0031] When the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is not greater than or equal to c% higher than the target pressure value P0, the system switches to the third high-speed switching valve. Here, a%, b%, and c% are set according to the actual loading conditions. a% represents the accumulator pressure margin, b% is the switching point between rapid pressure increase and precise pressure increase, and c% is the switching point between rapid pressure decrease and precise pressure decrease.

[0032] Furthermore, before the hydraulic control unit officially starts working, a hydraulic pump station is connected to the outside through the first hydraulic connector, the first shut-off valve is opened, high-pressure hydraulic oil is injected into the accumulator, and the reading of the first pressure sensor is observed. When the actual pressure value P2 of the accumulator reaches the maximum working pressure of the accumulator, the first shut-off valve is closed, and the pipeline connection between the first hydraulic connector and the hydraulic pump station is disconnected. An oil tank is connected to the outside through the second hydraulic connector, the second shut-off valve is opened until the oil in the oil tank is completely released, the pipeline connection between the second hydraulic connector and the oil tank is disconnected, and the second shut-off valve is closed.

[0033] Furthermore, the displacement sensor is a magnetostrictive displacement sensor, the displacement sensor housing is connected and fixed to the booster cylinder through a bracket, and the displacement sensor rod is connected and fixed to the booster cylinder piston rod through a connecting plate.

[0034] Furthermore, the mechanical unit also includes a metal clamp, and the accumulator housing and the oil storage tank housing are both connected and fixed to the booster cylinder through the metal clamp, thereby improving the stability against vibration and impact.

[0035] Furthermore, the mechanical unit also includes an eye bolt, which is mounted on the base plate for lifting.

[0036] Furthermore, the hydraulic control unit also includes a first pressure test connector and a second pressure test connector. The first pressure test connector is installed at the oil port of the accumulator, and the second pressure test connector is installed on the flow channel between the rod chamber of the booster cylinder and the oil inlet of the fourth high-speed switching valve. The first and second pressure test connectors serve as backup interfaces and can be connected to external hydraulic pressure gauges for monitoring the pressure of the accumulator and the rod chamber of the booster cylinder during system maintenance.

[0037] Furthermore, the relief valve serves as a safety valve. When the system is operating normally, the relief valve is in the closed state and only opens to overflow when the actual pressure value P1 of the rodless chamber of the hydraulic cylinder is greater than the safe pressure threshold of the hydraulic cylinder, thus providing overload protection for the system.

[0038] Furthermore, both the first and second hydraulic connectors are quick hydraulic connectors, which can be quickly connected and disconnected without tools, without leakage, and have a safety self-locking function.

[0039] The beneficial effects of this invention are as follows: This invention provides a high-precision hydraulic loading device without an external power source. This device adopts an integrated design, integrating mechanics, hydraulics, and control into one unit. It is easy to transport and carry, does not require an external hydraulic pump station as a power source, and has high versatility and compatibility, meeting different application scenarios and achieving multiple uses from one set. The digital hydraulic system, which organically combines a high-speed switching valve, accumulator, and booster cylinder, has high system loading capacity and flow output resolution. It meets the switching of four pressure control circuits and precise pressure control, including rapid boosting, precise boosting, rapid depressurization, and precise depressurization. Compared with proportional control and servo control analog hydraulic control, it reduces the system's throttling and overflow losses, has better reliability, stronger anti-interference ability, higher cost performance, and is easy to communicate with a computer. Attached Figure Description

[0040] Figure 1 Schematic diagram of the hydraulic system of the loading device;

[0041] Figure 2 The mechanical structure diagram of the loading device is shown below: (a) is the front view, (b) is the top view, and (c) is the axonometric view.

[0042] Figure 3 Schematic diagram of automatic pressure control principle for loading device;

[0043] Figure 4 Here is the logic diagram for switching the control valve of the loading device;

[0044] The components include: 1.1 accumulator, 1.2 first pressure testing connector, 1.3 first high-speed switching valve, 1.4 first pressure sensor, 1.5 second high-speed switching valve, 1.6 displacement sensor, 1.7 booster cylinder, 1.8 third high-speed switching valve, 1.9 relief valve, 1.10 oil tank, 1.11 fourth high-speed switching valve, 1.12 second pressure testing connector, 1.13 first hydraulic connector, 1.14 first shut-off valve, 1.15 second hydraulic connector, 1.16 second shut-off valve, 1.17 hydraulic hose, 1.18 second pressure sensor, 1.19 hydraulic cylinder, 2.1 base plate, 2.2 eye bolt, 2.3 first valve block, 2.4 second valve block, 2.5 metal clamp, 2.6 bracket, and 2.7 connecting plate. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0046] like Figure 1 , Figure 2 As shown, in one embodiment, the high-precision hydraulic loading device without an external power source includes: a hydraulic control unit, a hydraulic actuation unit, and a mechanical unit;

[0047] In one embodiment, such as Figure 1 As shown, the hydraulic control unit includes an accumulator 1.1, a first pressure testing connector 1.2, a first high-speed switching valve 1.3, a first pressure sensor 1.4, a second high-speed switching valve 1.5, a displacement sensor 1.6, a booster cylinder 1.7, a third high-speed switching valve 1.8, a relief valve 1.9, an oil reservoir 1.10, a fourth high-speed switching valve 1.11, a second pressure testing connector 1.12, a first hydraulic connector 1.13, a first shut-off valve 1.14, a second hydraulic connector 1.15, and a second shut-off valve 1.16.

[0048] The accumulator 1.1 serves as the system's power source, and its oil port is equipped with a first pressure testing connector 1.2 and a first pressure sensor 1.4. The oil inlet of the first high-speed switching valve 1.3 and the oil inlet of the second high-speed switching valve 1.5 are both connected to the accumulator 1.1.

[0049] The oil outlet of the first high-speed switching valve 1.3 is connected to the rodless chamber of the booster cylinder 1.7, and the oil outlet of the second high-speed switching valve 1.5 is connected to the rod chamber of the booster cylinder 1.7; the booster cylinder 1.7 is equipped with a displacement sensor 1.6 for detecting the stroke of its piston rod;

[0050] The oil inlet of the third high-speed switching valve 1.8 is connected to the rodless chamber of the booster cylinder 1.7, and the oil inlet of the fourth high-speed switching valve 1.11 is connected to the rod chamber of the booster cylinder 1.7.

[0051] An overflow valve 1.9 and a second pressure testing connector 1.12 are installed on the rod chamber of the booster cylinder 1.7 and the oil inlet flow channel of the fourth high-speed switching valve 1.11.

[0052] The oil outlet of the oil storage tank 1.10 is connected to the oil outlet of the third high-speed switch valve 1.8, the oil outlet of the overflow valve 1.9, and the oil outlet of the fourth high-speed switch valve 1.11;

[0053] The first hydraulic connector 1.13 is connected to the first shut-off valve 1.14 and communicates with the accumulator 1.1 for filling the accumulator 1.1 with liquid;

[0054] The second hydraulic connector 1.15 is connected to the second shut-off valve 1.16 and communicates with the oil storage tank 1.10 for draining the oil from the oil storage tank 1.10.

[0055] In one embodiment, such as Figure 1As shown, the hydraulic actuator includes a hydraulic hose 1.17, a second pressure sensor 1.18, and a hydraulic cylinder 1.19;

[0056] The rodless chamber of hydraulic cylinder 1.19 is connected to the rod chamber of booster cylinder 1.7 via hydraulic hose 1.17. The second pressure sensor 1.18 is used to monitor the pressure in the rodless chamber of hydraulic cylinder 1.19.

[0057] In one embodiment, such as Figure 2 As shown, the mechanical unit includes a base plate 2.1, a lifting eye screw 2.2, a first valve block 2.3, a second valve block 2.4, a metal clamp 2.5, a bracket 2.6, and a connecting plate 2.7;

[0058] Accumulator 1.1, first pressure testing connector 1.2, first high-speed switching valve 1.3, first pressure sensor 1.4, second high-speed switching valve 1.5, first hydraulic connector 1.13, and first shut-off valve 1.14 are all mounted on the first valve block 2.3, and the components are connected through the internal flow channel of the valve block;

[0059] The third high-speed switching valve 1.8, the overflow valve 1.9, the oil reservoir 1.10, the fourth high-speed switching valve 1.11, the second pressure test connector 1.12, the second hydraulic connector 1.15, and the second shut-off valve 1.16 are all installed on the second valve block 2.4, and each component is connected through the internal flow channel of the valve block;

[0060] The first valve block 2.3, the second valve block 2.4, and the booster cylinder 1.7 are all fixed to the base plate 2.1 with screws;

[0061] The eye bolt 2.2 is installed on the base plate 2.1 for hoisting; the outer shell of the accumulator 1.1 and the outer shell of the oil storage tank 1.10 are both connected and fixed to the booster cylinder 1.7 by metal clamps 2.5 to improve the stability against vibration and impact;

[0062] The displacement sensor 1.6 adopts a magnetostrictive displacement sensor. The housing of the displacement sensor 1.6 is connected and fixed to the booster cylinder 1.7 through the bracket 2.6, and the pull rod of the displacement sensor 1.6 is connected and fixed to the piston rod of the booster cylinder 1.7 through the connecting plate 2.7.

[0063] In one embodiment, the first high-speed switching valve 1.3, the second high-speed switching valve 1.5, the third high-speed switching valve 1.8, and the fourth high-speed switching valve 1.11 are normally closed two-position two-way valves. The opening and closing of the valve core are controlled by a pulse width modulation signal. When the pulse width modulation signal is high, the electromagnet of the high-speed switching valve is energized and the valve core opens; when the pulse width modulation signal is low, the electromagnet of the high-speed switching valve is de-energized and the valve core resets.

[0064] In one embodiment, the hydraulic control unit is designed with four pressure control circuits: when the electromagnet of the first high-speed switching valve 1.3 is energized, the high-pressure oil from the accumulator 1.1 flows through the first high-speed switching valve 1.3 to the rodless chamber of the booster cylinder 1.7, the piston rod of the booster cylinder 1.7 extends, and the oil from the rod chamber of the booster cylinder 1.7 enters the rodless chamber of the hydraulic cylinder 1.19 for precise pressure boosting; when the electromagnet of the second high-speed switching valve 1.5 is energized, the high-pressure oil from the accumulator 1.1 flows directly to the rodless chamber of the hydraulic cylinder 1.19 through the second high-speed switching valve 1.5 and the booster cylinder 1.7. The rod chamber is rapidly pressurized; when the electromagnet of the third high-speed switching valve 1.8 is energized, the high-pressure oil in the rodless chamber of the hydraulic cylinder 1.19 flows to the rod chamber of the booster cylinder 1.7, the piston rod of the booster cylinder 1.7 retracts, and the oil in the rodless chamber of the booster cylinder 1.7 flows back to the oil storage tank 1.10 through the third high-speed switching valve 1.8 for precise pressure reduction; when the electromagnet of the fourth high-speed switching valve 1.11 is energized, the high-pressure oil in the rodless chamber of the hydraulic cylinder 1.19 flows directly back to the oil storage tank 1.10 through the rod chamber of the booster cylinder 1.7 and the fourth high-speed switching valve 1.11 for rapid pressure reduction.

[0065] The piston rod area of ​​the rod chamber of booster cylinder 1.7 is smaller than that of the piston in the rodless chamber. The boosting ratio N is the ratio of the piston area of ​​the rodless chamber to that of the piston rod in the rod chamber. The input pressure required for the rodless chamber of booster cylinder 1.7 is 1 / N of the actual control pressure value P1 of the rodless chamber of hydraulic cylinder 1.19. This reduces the impact of the pressure drop of the accumulator 1.1 during the oil discharge process on the system control and improves the system loading capacity.

[0066]

[0067] Where D is the diameter of the piston in the rodless chamber of booster cylinder 1.7; d is the diameter of the piston rod in the rod chamber of booster cylinder 1.7;

[0068] Accumulator 1.1 adopts a bladder-type accumulator, which has low inertia and rapid response. The pre-charge nitrogen volume V at pressure P3 is:

[0069]

[0070] Where ΔV is the volume of oil to be discharged from accumulator 1.1, ΔV = V1N, and V1 is the volume of the rodless chamber at the maximum stroke of hydraulic cylinder 1.19; P min For the accumulator, the minimum operating pressure is 1.1, P min =P / N, where P is the rated pressure of the rodless chamber of the hydraulic cylinder 1.19; P3 is the charging pressure of the accumulator 1.1, taken as (0.8~0.9)P. min ;P max To determine the maximum operating pressure of accumulator 1.1 and avoid excessive deformation of the accumulator 1.1 airbag, P is selected. max ≤4P3; n is the gas state index. The gas compression and expansion of the accumulator 1.1 airbag changes slowly, so n = 1 is taken.

[0071] High-speed on / off valves utilize pulse width modulation (PWM) signal control, which adjusts the duty cycle τ to control the valve's on / off time, thereby achieving real-time flow regulation. The average flow rate of the high-speed on / off valve... It is directly proportional to the pulse width modulation duty cycle τ:

[0072]

[0073] Among them, Q max The output flow rate is when the valve is fully open; the duty cycle τ is the valve core opening time T. p The ratio to the period T; C d A is the valve orifice flow coefficient; m ΔP is the maximum flow area at the valve port; ρ is the pressure difference at the valve port;

[0074] When the electromagnet of the first high-speed switching valve 1.3 is energized for precise pressure boosting, the actual input flow rate of the rodless chamber of hydraulic cylinder 1.19 is equal to the input flow rate of the rodless chamber of booster cylinder 1.7. With 1 / N, the system flow and pressure control accuracy is further improved. The pressure change ΔP1 generated per unit time in the rodless chamber of hydraulic cylinder 1.19 is:

[0075]

[0076] Where β is the bulk modulus of hydraulic oil; V0 is the volume of the rodless chamber of the hydraulic cylinder (1.19).

[0077] When the electromagnet of the third high-speed switching valve 1.8 is energized for precise pressure reduction, the actual output flow of the rodless chamber of hydraulic cylinder 1.19 is the same as the output flow of the rodless chamber of booster cylinder 1.7. With a ratio of 1 / N, the accuracy of system flow and pressure control is also further improved.

[0078] In one embodiment, the hydraulic control unit is divided into a manual control mode and an automatic control mode: in the manual control mode, a pulse width modulation signal for the high-speed switching valve can be given separately to perform open-loop control of the pressure in the rodless chamber of the hydraulic cylinder 1.19;

[0079] like Figure 3As shown, in one embodiment, in automatic control mode, the actuator is a hydraulic cylinder 1.19, the detection element is a second pressure sensor 1.18, and the control elements are a first high-speed switching valve 1.3, a second high-speed switching valve 1.5, a third high-speed switching valve 1.8, and a fourth high-speed switching valve 1.11. Each high-speed switching valve is controlled by an independent pulse width modulation controller. A target pressure value P0 is set for the hydraulic cylinder 1.19. The actual pressure value P1 in the rodless chamber of the hydraulic cylinder 1.19 is detected by the second pressure sensor 1.18, thus obtaining the deviation signal e = P0 - P1. The control valve switching logic automatically switches the four high-speed switching valves. The pulse width modulation controller processes the system input deviation signal e and outputs a pulse width modulation signal, thereby controlling the movement of the valve core of the high-speed switching valve to control the output flow. Adjust until the pressure in the rodless chamber of hydraulic cylinder 1.19 reaches the target value P0.

[0080] like Figure 4 As shown, in one embodiment, the hydraulic control unit's control valve switching logic is determined by the target pressure value P0 of the hydraulic cylinder 1.19, the actual pressure value P1 of the rodless chamber of the hydraulic cylinder 1.19 detected by the second pressure sensor 1.18, and the actual pressure value P2 of the accumulator 1.1 detected by the first pressure sensor 1.4: when the target pressure value P0 is greater than the actual pressure value P1, and the accumulator 1.1 pressure value P2 is greater than or equal to a% higher than the actual pressure value P1, and the target pressure value P0 is greater than or equal to b% higher than the actual pressure value P1, the system switches to the second high-speed switching valve 1.5; when the target pressure value P0 is greater than the actual pressure value P1, the system switches to the second high-speed switching valve 1.5; when the target pressure value P0 is greater than the actual pressure value P1, the system switches to the second high-speed switching valve 1.5. 1. If the accumulator pressure value P2 is not greater than or equal to a% higher than the actual pressure value P1, or if the target pressure value P0 is not greater than or equal to b% higher than the actual pressure value P1, switch to the first high-speed switching valve 1.3; if the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is greater than or equal to c% higher than the target pressure value P0, switch to the fourth high-speed switching valve 1.11; if the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is not greater than or equal to c% higher than the target pressure value P0, switch to the third high-speed switching valve 1.8.

[0081] Among them, a%, b%, and c% can be customized according to the actual loading conditions: a% represents the accumulator's 1.1 pressure margin. The larger the value, the larger the pressure margin. Under the premise of ensuring the pressurization rate, it is generally taken as 10%; b% is the switching point between rapid pressurization and precise pressurization. The smaller the value, the faster the pressurization. In order to ensure the pressurization rate and pressure control accuracy, and reduce the impact of the control valve switching process on the system pressure, it is generally taken as 5%; c% is the switching point between rapid pressure reduction and precise pressure reduction. The smaller the value, the faster the pressure reduction. In order to ensure the pressure reduction rate and pressure control accuracy, and reduce the impact of the control valve switching process on the system pressure, it is generally taken as 5%.

[0082] In one embodiment, before the hydraulic control unit officially starts working, an external hydraulic pump station is connected through the first hydraulic connector 1.13, the first shut-off valve 1.14 is opened, and high-pressure hydraulic oil is injected into the accumulator 1.1. The reading of the first pressure sensor 1.4 is observed. When the actual pressure value P2 of the accumulator 1.1 reaches the maximum working pressure P of the accumulator 1.1, the hydraulic oil is injected into the accumulator. max Then, close the first shut-off valve 1.14, disconnect the pipeline connection between the first hydraulic connector 1.13 and the hydraulic pump station; connect the oil tank through the second hydraulic connector 1.15, open the second shut-off valve 1.16 until the oil in the oil storage tank 1.10 is completely released, disconnect the pipeline connection between the second hydraulic connector 1.15 and the oil tank, and close the second shut-off valve 1.16.

[0083] In one embodiment, the relief valve 1.9 serves as a safety valve. When the system is operating normally, the relief valve 1.9 is in a closed state. It only opens to overflow when the actual pressure value P1 of the rodless chamber of the hydraulic cylinder 1.19 is greater than the safety pressure threshold of the hydraulic cylinder 1.19, thus providing overload protection for the system.

[0084] In one embodiment, the first pressure test connector 1.2 and the second pressure test connector 1.12 serve as backup interfaces and can be connected to an external hydraulic pressure gauge for monitoring the rod chamber pressure of the accumulator 1.1 and the booster cylinder 1.7 during system maintenance.

[0085] In one embodiment, the first hydraulic connector 1.13 and the second hydraulic connector 1.15 are both hydraulic quick connectors, which can quickly install and disconnect pipelines without the need for tools, without leakage, and have a safety self-locking function.

[0086] The above are merely implementation examples of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention without creative effort are included within the scope of protection of the present invention.

Claims

1. A high-precision hydraulic loading device without an external power source, characterized in that, The device includes a hydraulic control unit, a hydraulic actuator unit, and a mechanical unit; The hydraulic control unit includes an accumulator, a first high-speed switching valve, a first pressure sensor, a second high-speed switching valve, a displacement sensor, a booster cylinder, a third high-speed switching valve, a relief valve, an oil reservoir, a fourth high-speed switching valve, a first hydraulic connector, a first shut-off valve, a second hydraulic connector, and a second shut-off valve. A first pressure sensor is installed at the oil port of the accumulator. The oil inlets of both the first and second high-speed switching valves are connected to the accumulator. The oil outlet of the first high-speed switching valve is connected to the rodless chamber of the booster cylinder, and the oil outlet of the second high-speed switching valve is connected to the rod chamber of the booster cylinder. The booster cylinder is equipped with a displacement sensor to detect the stroke of its piston rod. The inlet of the third high-speed switching valve is connected to the rodless chamber of the booster cylinder, and the inlet of the fourth high-speed switching valve is connected to the rod chamber of the booster cylinder; an overflow valve is provided on the flow channel of the rod chamber of the booster cylinder and the inlet of the fourth high-speed switching valve; the oil outlet of the oil storage tank is connected to the outlet of the third high-speed switching valve, the outlet of the overflow valve, and the outlet of the fourth high-speed switching valve; the first hydraulic connector is connected to the first shut-off valve and to the accumulator for filling the accumulator; the second hydraulic connector is connected to the second shut-off valve and to the oil storage tank for draining the oil storage tank; The hydraulic actuator includes a hydraulic hose, a second pressure sensor, and a hydraulic cylinder; the rodless chamber of the hydraulic cylinder is connected to the rod chamber of the booster cylinder via the hydraulic hose, and the second pressure sensor is used to monitor the pressure in the rodless chamber of the hydraulic cylinder. The mechanical unit includes a base plate, a first valve block, and a second valve block. The accumulator, the first high-speed switching valve, the first pressure sensor, the second high-speed switching valve, the first hydraulic connector, and the first shut-off valve are all mounted on the first valve block, and all components are connected through the internal flow channels of the valve block. The third high-speed switching valve, the overflow valve, the oil storage tank, the fourth high-speed switching valve, the second hydraulic connector, and the second shut-off valve are all mounted on the second valve block, and all components are connected through the internal flow channels of the valve block. The first valve block, the second valve block, and the booster cylinder are fixed on the base plate. The accumulator housing and the oil storage tank housing are connected and fixed to the booster cylinder. The first, second, third, and fourth high-speed switching valves are normally closed two-position two-way valves. The opening and closing of the valve core are controlled by a pulse width modulation signal. When the pulse width modulation signal is high, the electromagnet of the high-speed switching valve is energized and the valve core opens; when the pulse width modulation signal is low, the electromagnet of the high-speed switching valve is de-energized and the valve core resets. The hydraulic control unit has four pressure control circuits: When the first high-speed switching valve solenoid is energized, the high-pressure oil from the accumulator flows through the first high-speed switching valve to the rodless chamber of the booster cylinder, the piston rod of the booster cylinder extends, and the oil from the rod chamber of the booster cylinder enters the rodless chamber of the hydraulic cylinder for precise pressure boosting; when the second high-speed switching valve solenoid is energized, the high-pressure oil from the accumulator flows through the second high-speed switching valve and the rod chamber of the booster cylinder directly to the rodless chamber of the hydraulic cylinder for rapid pressure boosting; when the third high-speed switching valve solenoid is energized, the high-pressure oil from the rodless chamber of the hydraulic cylinder flows to the rod chamber of the booster cylinder, the piston rod of the booster cylinder retracts, and the oil from the rodless chamber of the booster cylinder flows back to the oil storage tank through the third high-speed switching valve for precise pressure reduction; when the fourth high-speed switching valve solenoid is energized, the high-pressure oil from the rodless chamber of the hydraulic cylinder flows through the rod chamber of the booster cylinder and the fourth high-speed switching valve directly back to the oil storage tank for rapid pressure reduction.

2. The high-precision hydraulic loading device without an external power source according to claim 1, characterized in that, The piston rod area of ​​the rod chamber of the booster cylinder is smaller than the piston area of ​​the rodless chamber. The boosting ratio N is the ratio of the piston area of ​​the rodless chamber to the piston rod area of ​​the rod chamber. The required input pressure of the rodless chamber of the booster cylinder is 1 / N of the actual control pressure value of the rodless chamber of the hydraulic cylinder. Pulse width modulation (PWM) signal control of high-speed switching valves, that is, controlling the valve's on / off time by adjusting the duty cycle τ, achieves real-time flow regulation. The average flow rate of the high-speed switching valve... It is directly proportional to the pulse width modulation duty cycle τ; When the electromagnet of the first high-speed switching valve is energized for precise pressure boosting, the actual input flow rate of the rodless chamber of the hydraulic cylinder is equal to the input flow rate of the rodless chamber of the booster cylinder. The accuracy of system flow and pressure control is further improved by 1 / N; When the third high-speed switching valve solenoid is energized for precise pressure reduction, the actual output flow of the rodless chamber of the hydraulic cylinder is the same as the output flow of the rodless chamber of the booster cylinder. With a ratio of 1 / N, the accuracy of system flow and pressure control is also further improved.

3. The high-precision hydraulic loading device without an external power source according to claim 2, characterized in that, The accumulator is a bladder-type accumulator, and the pre-charged nitrogen volume V at pressure P3 is: Where ΔV is the volume of oil to be discharged by the accumulator, ΔV = V1N, and V1 is the volume of the rodless chamber at the maximum stroke of the hydraulic cylinder; P min P is the minimum operating pressure for the accumulator. min =P / N, where P is the rated pressure of the rodless chamber of the hydraulic cylinder; P3 is the accumulator charging pressure; P max ρ is the maximum operating pressure of the accumulator; n is the gas state index.

4. The high-precision hydraulic loading device without an external power source according to claim 2, characterized in that, The average flow rate of the high-speed switching valve It is directly proportional to the pulse width modulation duty cycle τ, as shown in the following formula: Among them, Q max The output flow rate is when the valve is fully open; the duty cycle τ is the valve core opening time T. p The ratio to the period T; C d A is the valve orifice flow coefficient; m ρ is the maximum flow area at the valve port; ΔP is the valve port pressure difference; and ρ is the hydraulic oil density.

5. A high-precision hydraulic loading device without an external power source according to claim 4, characterized in that, The pressure change ΔP1 generated per unit time in the rodless chamber of the hydraulic cylinder is: Where β is the bulk modulus of hydraulic oil; V0 is the volume of the rodless chamber of the hydraulic cylinder.

6. The high-precision hydraulic loading device without an external power source according to claim 1, characterized in that, The hydraulic control unit is divided into manual control mode and automatic control mode; in the manual control mode, a pulse width modulation signal of the high-speed switching valve can be given separately to perform open-loop control of the pressure in the rodless chamber of the hydraulic cylinder. In the automatic control mode, the actuator is a hydraulic cylinder, the detection element is a second pressure sensor, and the control elements are a first high-speed switching valve, a second high-speed switching valve, a third high-speed switching valve, and a fourth high-speed switching valve. Each high-speed switching valve is controlled by an independent pulse width modulation controller. The target pressure value P0 of the hydraulic cylinder is set, and the actual pressure value P1 of the rodless chamber of the hydraulic cylinder is detected by the second pressure sensor, thereby obtaining the deviation signal e = P0 - P1. The control valve switching logic automatically switches the four high-speed switching valves. The pulse width modulation controller processes the deviation signal e input by the system and outputs a pulse width modulation signal, thereby controlling the movement of the valve core of the high-speed switching valve to regulate the output flow until the pressure in the rodless chamber of the hydraulic cylinder reaches the target value P0.

7. The high-precision hydraulic loading device without an external power source according to claim 1, characterized in that, The control valve switching logic of the hydraulic control unit is determined by the target pressure value P0 of the hydraulic cylinder, the actual pressure value P1 of the rodless chamber of the hydraulic cylinder detected by the second pressure sensor, and the actual pressure value P2 of the accumulator detected by the first pressure sensor. When the target pressure value P0 is greater than the actual pressure value P1, and the accumulator pressure value P2 is greater than or equal to a% higher than the actual pressure value P1, and the target pressure value P0 is greater than or equal to b% higher than the actual pressure value P1, switch to the second high-speed switching valve. When the target pressure value P0 is greater than the actual pressure value P1, and the accumulator pressure value P2 is not greater than or equal to a% higher than the actual pressure value P1, or the target pressure value P0 is not greater than or equal to b% higher than the actual pressure value P1, switch to the first high-speed switching valve. When the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is greater than or equal to c% higher than the target pressure value P0, switch to the fourth high-speed switching valve. When the target pressure value P0 is not greater than the actual pressure value P1, and the actual pressure value P1 is not greater than or equal to c% higher than the target pressure value P0, the system switches to the third high-speed switching valve. Here, a%, b%, and c% are set according to the actual loading conditions. a% represents the accumulator pressure margin, b% is the switching point between rapid pressure increase and precise pressure increase, and c% is the switching point between rapid pressure decrease and precise pressure decrease.

8. A high-precision hydraulic loading device without an external power source according to claim 7, characterized in that, Before the hydraulic control unit officially starts working, a hydraulic pump station is connected to the outside through the first hydraulic connector, the first shut-off valve is opened, and high-pressure hydraulic oil is injected into the accumulator. The reading of the first pressure sensor is observed. When the actual pressure value P2 of the accumulator reaches the maximum working pressure of the accumulator, the first shut-off valve is closed, and the pipeline connection between the first hydraulic connector and the hydraulic pump station is disconnected. An oil tank is connected to the outside through the second hydraulic connector, the second shut-off valve is opened until the oil in the oil tank is completely released, the pipeline connection between the second hydraulic connector and the oil tank is disconnected, and the second shut-off valve is closed.

9. A high-precision hydraulic loading device without an external power source according to claim 1, characterized in that, The displacement sensor is a magnetostrictive displacement sensor. The displacement sensor housing is connected and fixed to the booster cylinder via a bracket, and the displacement sensor rod is connected and fixed to the booster cylinder piston rod via a connecting plate. The mechanical unit also includes metal clamps, and the accumulator housing and the oil storage tank housing are both connected and fixed to the booster cylinder through metal clamps to improve the stability against vibration and impact; the mechanical unit also includes eye bolts, which are installed on the base plate for hoisting. The hydraulic control unit also includes a first pressure test connector and a second pressure test connector. The first pressure test connector is installed at the oil port of the accumulator, and the second pressure test connector is installed on the flow channel between the rod chamber of the booster cylinder and the oil inlet of the fourth high-speed switching valve. The first and second pressure test connectors serve as backup interfaces and can be connected to external hydraulic pressure gauges for monitoring the pressure of the accumulator and the rod chamber of the booster cylinder during system maintenance.

10. A high-precision hydraulic loading device without an external power source according to claim 1, characterized in that, The relief valve acts as a safety valve. When the system is working normally, the relief valve is in the closed state. It only opens to overflow when the actual pressure value P1 of the rodless chamber of the hydraulic cylinder is greater than the safe pressure threshold of the hydraulic cylinder, thus providing overload protection for the system.

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