阅读说明：本技术 柱塞缸测试液压系统 (Plunger cylinder test hydraulic system ) 是由 周伟军 孙夕龙 徐海林 于 2020-12-25 设计创作，主要内容包括：本发明提供一种柱塞缸测试液压系统,包括：主驱动电机、双联泵、第一单向阀、第三压力表、第一溢流阀、第二溢流阀、高压泄压阀、第一换向阀、双向液压锁、第一锁紧油缸、第二锁紧油缸、第二换向阀、双向溢流阀、随动阀、第一液压马达、第二液压马达、第一压力传感器、第二压力传感器、蓄能器、第三换向阀、第一液控单向阀、第二液控单向阀；主驱动电机连接双联泵,双联泵包括高压泵和低压泵；高压泵的入口和低压泵的入口分别通过管路接液压油箱；本发明可实现柱塞缸的压力和行程测试。(The invention provides a plunger cylinder testing hydraulic system, which comprises: the hydraulic control system comprises a main driving motor, a dual pump, a first check valve, a third pressure gauge, a first overflow valve, a second overflow valve, a high-pressure relief valve, a first reversing valve, a two-way hydraulic lock, a first locking oil cylinder, a second reversing valve, a two-way overflow valve, a servo valve, a first hydraulic motor, a second hydraulic motor, a first pressure sensor, a second pressure sensor, an energy accumulator, a third reversing valve, a first hydraulic control check valve and a second hydraulic control check valve; the main driving motor is connected with a duplex pump, and the duplex pump comprises a high-pressure pump and a low-pressure pump; the inlet of the high-pressure pump and the inlet of the low-pressure pump are respectively connected with a hydraulic oil tank through pipelines; the invention can realize the pressure and stroke test of the plunger cylinder.)

1. A plunger cylinder testing hydraulic system, comprising:

the hydraulic control system comprises a main driving motor (11), a dual pump (12), a first check valve (13), a third pressure gauge (14C), a first overflow valve (15), a second overflow valve (16), a high-pressure relief valve (17), a first reversing valve (18), a bidirectional hydraulic lock (19), a first locking oil cylinder (20A), a second locking oil cylinder (20B), a second reversing valve (21), a bidirectional overflow valve (22), a servo valve (23), a first hydraulic motor (24A), a second hydraulic motor (24B), a first pressure sensor (25A), a second pressure sensor (25B), an energy accumulator (26), a third reversing valve (27), a first hydraulic control check valve (28) and a second hydraulic control check valve (29);

the main driving motor (11) is connected with a double pump (12), and the double pump (12) comprises a high-pressure pump and a low-pressure pump; the inlet of the high-pressure pump and the inlet of the low-pressure pump are respectively connected with a hydraulic oil tank (1) through pipelines;

the outlet of the low-pressure pump is connected with the inlet of the first check valve (13) through a pipeline, a first overflow valve (15) is further connected to the pipeline between the outlet of the low-pressure pump and the inlet of the first check valve (13), and the outlet of the first overflow valve (15) is connected with the hydraulic oil tank (1) through a pipeline; the outlet of the high-pressure pump is connected with the pipeline of the outlet of the first one-way valve (13) through a pipeline;

the outlet of the first one-way valve (13) is connected with a second overflow valve (16), a P port of a high-pressure relief valve (17), a P port of a first reversing valve (18), a P port of a second reversing valve (21) and a P port of a third reversing valve (27) through pipelines; the outlet of the second overflow valve (16) is connected with the hydraulic oil tank (1) through a pipeline; a T port of the first reversing valve (18) is connected with the hydraulic oil tank (1) through a pipeline; a T port of the second reversing valve (21) is connected with the hydraulic oil tank (1) through a pipeline; a T port of the third reversing valve (27) is connected with the oil tank (1) through a pipeline;

the high-pressure relief valve (17) is an H-shaped functional reversing valve, and an A port and a B port of the high-pressure relief valve are plugged;

the first reversing valve (18) is an O-shaped neutral position function reversing valve;

the second reversing valve (21) and the third reversing valve (27) are Y-shaped neutral position function reversing valves;

the port A and the port B of the first reversing valve (18) are respectively connected with two inlets of a bidirectional hydraulic lock (19); one outlet of the bidirectional hydraulic lock (19) is connected with the rod cavities of the first locking oil cylinder (20A) and the second locking oil cylinder (20B) through a pipeline, and the other outlet of the bidirectional hydraulic lock (19) is connected with the rodless cavities of the first locking oil cylinder (20A) and the second locking oil cylinder (20B) through a pipeline;

the port A and the port B of the second reversing valve (21) are respectively connected with two inlets of a bidirectional overflow valve (22) through pipelines; a first pressure sensor (25A) is arranged on a pipeline between the port A of the second reversing valve (21) and one inlet of the two-way overflow valve (22); one outlet of the two-way overflow valve (22) is respectively connected with one end of a first hydraulic motor (24A) and one end of a second hydraulic motor (24B) and a P port of a follow-up valve (23) through pipelines; the other outlet of the two-way overflow valve (22) is respectively connected with the other ends of the first hydraulic motor (24A) and the second hydraulic motor (24B) and the port A of the servo valve (23) through pipelines; the oil return ports of the first hydraulic motor (24A) and the second hydraulic motor (24B) are connected with a hydraulic oil tank (1) through pipelines;

the A port of the third reversing valve (27) is connected with the inlet of the first hydraulic control one-way valve (28) through a pipeline, and the outlet of the first hydraulic control one-way valve (28) is connected with the outlet of the second hydraulic control one-way valve (29) and the test workpiece (31) through a pipeline; a pipeline between the outlet of the first hydraulic control one-way valve (28) and the test workpiece (31) is also connected with a third pressure gauge (14C), a second pressure sensor (25B) and an energy accumulator (26); the port B of the third reversing valve (27) is connected with the hydraulic control ports of the first hydraulic control one-way valve (28) and the second hydraulic control one-way valve (29) through pipelines; the inlet of the second hydraulic control one-way valve (29) is connected with the hydraulic oil tank (1) through a pipeline.

2. The plunger cylinder testing hydraulic system of claim 1,

the servo valve (23) is a two-position four-way electromagnetic valve, and a port P is communicated with a port A and a port T is communicated with a port B in a normal state; the T port and the B port of the slave valve 23 are plugged; when the slave valve (23) is electrified, the port P is communicated with the port B, and the port T is communicated with the port A.

3. The plunger cylinder testing hydraulic system of claim 1,

the two-way overflow valve (22) adopts a pressure-adjustable two-way overflow valve.

4. The plunger cylinder testing hydraulic system of claim 1,

the first pressure sensor (25A) and the second pressure sensor (25B) adopt adjustable pressure sensors.

5. The plunger cylinder testing hydraulic system of claim 1,

a first pressure gauge (14A) is also arranged on a pipeline between the outlet of the low-pressure pump and the inlet of the first check valve (13).

6. The plunger cylinder testing hydraulic system of claim 1,

and a second pressure gauge (14B) is also arranged on an outlet pipeline of the first check valve (13).

7. The plunger cylinder testing hydraulic system of claim 1,

a first oil absorption filter core (4) is also arranged on an inlet pipeline of the high-pressure pump; and a second oil absorption filter element (5) is also arranged on the inlet pipeline of the low-pressure pump.

8. The plunger cylinder testing hydraulic system according to any one of claims 1 to 7,

and a first oil return filter (3) is also arranged on a pipeline leading to the hydraulic oil tank (1) from the T port of the third reversing valve (27) and the inlet of the second hydraulic control one-way valve (29).

9. The plunger cylinder testing hydraulic system according to any one of claims 1 to 8,

the hydraulic oil circulating filter device is characterized by further comprising a hydraulic oil tank (1), wherein a hydraulic oil circulating filter device is arranged on the hydraulic oil tank.

10. The plunger cylinder testing hydraulic system of claim 9,

the hydraulic oil circulating and filtering device comprises a third oil absorption filter element (6), a second oil return filter (7), a gear pump (9) and a circulating motor (10); the circulating motor (10) is connected with a gear pump (9), and an inlet and an outlet of the gear pump (9) respectively extend into the hydraulic oil tank (1) through pipelines; a third oil absorption filter element (6) is arranged on a pipeline at the inlet of the gear pump (9), and a second oil return filter (7) is arranged on a pipeline at the outlet of the gear pump (9).

Technical Field

The invention relates to plunger cylinder testing equipment, in particular to a plunger cylinder testing hydraulic system.

Background

Because the plunger cylinder can only move in a single direction, the testing system used in China at present adopts a double-cylinder opposite-jacking type system or a single motor and chain drive, the double-cylinder opposite-jacking type system has the disadvantages of large flow, more control elements, large floor area of equipment and inconvenient maintenance; the single motor drive and the chain drive require large motor power, the integral control element is difficult to select types, and the single motor drive is easy to be eccentric, so that the locking is caused, the system fault is caused, and the test requirements of various plunger cylinders cannot be met.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a plunger cylinder testing hydraulic system which can realize the pressure and stroke testing of a plunger cylinder. The technical scheme adopted by the invention is as follows:

a plunger cylinder testing hydraulic system comprising:

the hydraulic control system comprises a main driving motor, a dual pump, a first check valve, a third pressure gauge, a first overflow valve, a second overflow valve, a high-pressure relief valve, a first reversing valve, a two-way hydraulic lock, a first locking oil cylinder, a second reversing valve, a two-way overflow valve, a servo valve, a first hydraulic motor, a second hydraulic motor, a first pressure sensor, a second pressure sensor, an energy accumulator, a third reversing valve, a first hydraulic control check valve and a second hydraulic control check valve;

the main driving motor is connected with a duplex pump, and the duplex pump comprises a high-pressure pump and a low-pressure pump; the inlet of the high-pressure pump and the inlet of the low-pressure pump are respectively connected with a hydraulic oil tank through pipelines;

the outlet of the low-pressure pump is connected with the inlet of the first one-way valve through a pipeline, a first overflow valve is further connected to the pipeline between the outlet of the low-pressure pump and the inlet of the first one-way valve, and the outlet of the first overflow valve is connected with a hydraulic oil tank through a pipeline; the outlet of the high-pressure pump is connected with the pipeline of the outlet of the first one-way valve through a pipeline;

the outlet of the first one-way valve is connected with the second overflow valve, the P port of the high-pressure relief valve, the P port of the first reversing valve, the P port of the second reversing valve and the P port of the third reversing valve through pipelines; the outlet of the second overflow valve is connected with a hydraulic oil tank through a pipeline; the T port of the first reversing valve is connected with a hydraulic oil tank through a pipeline; the T port of the second reversing valve is connected with a hydraulic oil tank through a pipeline; the T port of the third reversing valve is connected with an oil tank through a pipeline;

the high-pressure relief valve is an H-shaped functional reversing valve, and an opening A and an opening B of the high-pressure relief valve are plugged;

the first reversing valve is an O-shaped neutral position function reversing valve;

the second reversing valve and the third reversing valve are Y-shaped neutral position function reversing valves;

the port A and the port B of the first reversing valve are respectively connected with two inlets of the bidirectional hydraulic lock; one outlet of the bidirectional hydraulic lock is connected with the rod cavities of the first locking oil cylinder and the second locking oil cylinder through a pipeline, and the other outlet of the bidirectional hydraulic lock is connected with the rodless cavities of the first locking oil cylinder and the second locking oil cylinder through a pipeline;

the port A and the port B of the second reversing valve are respectively connected with two inlets of the bidirectional overflow valve through pipelines; a first pressure sensor is arranged on a pipeline between the port A of the second reversing valve and one inlet of the two-way overflow valve; one outlet of the two-way overflow valve is respectively connected with one end of the first hydraulic motor and one end of the second hydraulic motor and the P port of the servo valve through pipelines; the other outlet of the bidirectional overflow valve is respectively connected with the other ends of the first hydraulic motor and the second hydraulic motor and the port A of the servo valve through pipelines; the oil return ports of the first hydraulic motor and the second hydraulic motor are connected with a hydraulic oil tank through pipelines;

the port A of the third reversing valve is connected with the inlet of the first hydraulic control one-way valve through a pipeline, and the outlet of the first hydraulic control one-way valve is connected with the outlet of the second hydraulic control one-way valve and the test workpiece through a pipeline; a third pressure gauge, a second pressure sensor and an energy accumulator are also connected to a pipeline between the outlet of the first hydraulic control one-way valve and the test workpiece; the port B of the third reversing valve is connected with the hydraulic control ports of the first hydraulic control one-way valve and the second hydraulic control one-way valve through pipelines; the inlet of the second hydraulic control one-way valve is connected with the hydraulic oil cylinder through a pipeline.

Furthermore, the servo valve is a two-position four-way electromagnetic valve, and the port P is communicated with the port A and the port T is communicated with the port B in a normal state; the T port and the B port of the slave valve are plugged; when the slave valve is electrified, the port P is communicated with the port B, and the port T is communicated with the port A.

Furthermore, the two-way overflow valve adopts a pressure-adjustable two-way overflow valve.

Further, the first pressure sensor and the second pressure sensor adopt adjustable pressure sensors.

Furthermore, a first pressure gauge is further arranged on a pipeline between the outlet of the low-pressure pump and the inlet of the first check valve.

Furthermore, a second pressure gauge is arranged on an outlet pipeline of the first one-way valve.

Furthermore, a first oil absorption filter core is arranged on an inlet pipeline of the high-pressure pump; and a second oil absorption filter element is also arranged on the inlet pipeline of the low-pressure pump.

Furthermore, a first oil return filter is further arranged on a pipeline leading to the hydraulic oil tank from the T port of the third reversing valve and the inlet of the second hydraulic control one-way valve.

Furthermore, the plunger cylinder test hydraulic system further comprises a hydraulic oil tank, and a hydraulic oil circulating and filtering device is configured on the hydraulic oil tank.

Furthermore, the hydraulic oil circulating and filtering device comprises a third oil absorption filter core, a second oil return filter, a gear pump and a circulating motor; the circulating motor is connected with a gear pump, and an inlet and an outlet of the gear pump respectively extend into the hydraulic oil tank through pipelines; and a third oil absorption filter element is arranged on a pipeline at the inlet of the gear pump, and a second oil return filter is arranged on a pipeline at the outlet of the gear pump.

The invention has the advantages that:

1, a duplex pump is adopted for confluence, a one-way valve automatically maintains pressure, an energy accumulator absorbs impact, and energy consumption is reduced.

2, a plurality of groups of filtering systems are arranged to ensure the cleanliness of oil.

And 3, the double motors are adopted for driving, so that the efficiency is high, and the operation is stable.

4, the motors are designed in parallel, the driving flow is small, control elements are reduced, and the service life is prolonged.

And 5, a pressure-adjustable two-way overflow valve is adopted, so that the loaded starting of the hydraulic motor is ensured, and the idling is prevented.

And 6, an adjustable pressure sensor is arranged in the system to control the pressure of the system and ensure safety.

And 7, setting position signal detection to realize the detection of various workpieces.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that, the meaning of the connection between the components in the present invention may be direct connection or indirect connection through a pipeline, etc.;

the embodiment of the invention provides a plunger cylinder testing hydraulic system, which comprises the following components as shown in figure 1:

the hydraulic control system comprises a main driving motor 11, a dual pump 12, a first check valve 13, a first pressure gauge 14A, a second pressure gauge 14B, a third pressure gauge 14C, a first overflow valve 15, a second overflow valve 16, a high-pressure relief valve 17, a first reversing valve 18, a bidirectional hydraulic lock 19, a first locking oil cylinder 20A, a second locking oil cylinder 20B, a second reversing valve 21, a bidirectional overflow valve 22, a servo valve 23, a first hydraulic motor 24A, a second hydraulic motor 24B, a first pressure sensor 25A, a second pressure sensor 25B, an energy accumulator 26, a third reversing valve 27, a first hydraulic control check valve 28 and a second hydraulic control check valve 29;

the plunger cylinder test hydraulic system is matched with the hydraulic oil tank 1 for use during testing; an oil filling port of the hydraulic oil tank 1 is provided with an air filter 2; a first oil return filter 3, a first oil absorption filter core 4 and a second oil absorption filter core 5 are arranged in the hydraulic oil tank 1; the hydraulic oil tank 1 is also provided with a hydraulic oil circulating and filtering device, and the hydraulic oil circulating and filtering device comprises a third oil absorption filter core 6, a second oil return filter 7, a gear pump 9 and a circulating motor 10; the circulating motor 10 is connected with a gear pump 9, and an inlet and an outlet of the gear pump 9 respectively extend into the hydraulic oil tank 1 through pipelines; a third oil absorption filter core 6 is arranged on a pipeline at the inlet of the gear pump 9, and a second oil return filter 7 is arranged on a pipeline at the outlet of the gear pump 9; a liquid level meter 8 is also arranged in the hydraulic oil tank 1; the test workpiece 31 is a plunger cylinder;

the main driving motor 11 is connected with a duplex pump 12, and the duplex pump 12 comprises a high-pressure pump and a low-pressure pump; the inlet of the high-pressure pump and the inlet of the low-pressure pump are respectively connected with a hydraulic oil tank 1 through pipelines, a first oil absorption filter core 4 is further arranged on an inlet pipeline of the high-pressure pump, and a second oil absorption filter core 5 is further arranged on an inlet pipeline of the low-pressure pump;

the outlet of the low-pressure pump is connected with the inlet of the first check valve 13 through a pipeline, a first overflow valve 15 is further connected to the pipeline between the outlet of the low-pressure pump and the inlet of the first check valve 13, and the outlet of the first overflow valve 15 is connected with the hydraulic oil tank 1 through a pipeline; a first pressure gauge 14A is also arranged on a pipeline between the outlet of the low-pressure pump and the inlet of the first check valve 13; the outlet of the high-pressure pump is connected with the pipeline of the outlet of the first one-way valve 13 through a pipeline;

the outlet of the first check valve 13 is connected with a second overflow valve 16, a P port of a high-pressure relief valve 17, a P port of a first reversing valve 18, a P port of a second reversing valve 21 and a P port of a third reversing valve 27 through pipelines; the outlet of the second overflow valve 16 is connected with the hydraulic oil tank 1 through a pipeline; the T port of the first reversing valve 18 is connected with the hydraulic oil tank 1 through a pipeline; the T port of the second reversing valve 21 is connected with the hydraulic oil tank 1 through a pipeline; the T port of the third reversing valve 27 is connected with the oil tank 1 through a pipeline; a second pressure gauge 14B is also arranged on an outlet pipeline of the first check valve 13;

the high-pressure relief valve 17 is an H-shaped functional reversing valve, and an opening A and an opening B of the high-pressure relief valve are plugged;

the first direction valve 18 is an O-shaped middle position function direction valve;

the second reversing valve 21 and the third reversing valve 27 are Y-shaped neutral position function reversing valves;

the port A and the port B of the first reversing valve 18 are respectively connected with two inlets of a bidirectional hydraulic lock 19; one outlet (the left side in the figure 1) of the bidirectional hydraulic lock 19 is connected with the rod cavities of the first locking oil cylinder 20A and the second locking oil cylinder 20B through a pipeline, and the other outlet (the right side in the figure 1) of the bidirectional hydraulic lock 19 is connected with the rodless cavities of the first locking oil cylinder 20A and the second locking oil cylinder 20B through a pipeline;

the port A and the port B of the second reversing valve 21 are respectively connected with two inlets of a two-way overflow valve 22 through pipelines; a first pressure sensor 25A is arranged on a pipeline between the port A of the second reversing valve 21 and one inlet of the two-way overflow valve 22; one outlet of the two-way overflow valve 22 is respectively connected with one end of a first hydraulic motor 24A and one end of a second hydraulic motor 24B and a P port of a follow-up valve 23 through pipelines; the other outlet of the two-way overflow valve 22 is respectively connected with the other ends of the first hydraulic motor 24A and the second hydraulic motor 24B and the port A of the slave valve 23 through pipelines; the oil return ports of the first hydraulic motor 24A and the second hydraulic motor 24B are connected with the hydraulic oil tank 1 through pipelines;

the servo valve 23 is a two-position four-way electromagnetic valve, and the port P is communicated with the port A and the port T is communicated with the port B in a normal state; the T port and the B port of the slave valve 23 are plugged; when the servo valve 23 is electrified, the port P is communicated with the port B, and the port T is communicated with the port A; that is, when the spool valve 23 is powered on, the oil path of the spool valve is broken;

the A port of the third reversing valve 27 is connected with the inlet of the first hydraulic control one-way valve 28 through a pipeline, and the outlet of the first hydraulic control one-way valve 28 is connected with the outlet of the second hydraulic control one-way valve 29 and the test workpiece 31 through a pipeline; a third pressure gauge 14C, a second pressure sensor 25B and an energy accumulator 26 are also connected on a pipeline between the outlet of the first hydraulic control one-way valve 28 and the test workpiece 31; the port B of the third reversing valve 27 is connected with the hydraulic control ports of the first hydraulic control one-way valve 28 and the second hydraulic control one-way valve 29 through pipelines; the inlet of the second hydraulic control one-way valve 29 is connected with the hydraulic oil tank 1 through a pipeline;

a first oil return filter 3 is also arranged on a pipeline of the T port of the third reversing valve 27 and the inlet of the second hydraulic control one-way valve 29 which lead to the hydraulic oil tank 1.

Preferably, the two-way overflow valve 22 is a pressure-adjustable two-way overflow valve. The first pressure sensor 25A and the second pressure sensor 25B can adjust the pressure sensors.

When a test workpiece 31 (plunger cylinder) needs to be tested, the front end of the test workpiece 31 (plunger cylinder) is abutted against a trolley, and a left hydraulic motor 24A and a right hydraulic motor 24B are arranged below the trolley; a proximity switch 30 is arranged in front of the trolley;

the test mainly comprises the following two processes:

1) the test is started: the method comprises the steps of (1) advancing a test workpiece 31 (plunger cylinder) (forward rotation and forward follow-up of hydraulic motors 24A and 24B) -stroke detection (proximity switch 30) -locking cylinder extension (20A and 20B) -pressure detection (14C and 25B) -pressure maintaining test (low energy consumption state); the method comprises the following specific steps:

the test is started: the main driving motor 11 is started, the double pump 12 is operated, the high pressure and the low pressure are set by the first overflow valve 15 and the second overflow valve 16, the EV6 of the high pressure relief valve 17 is electrically commutated (when the EV6 is powered off, hydraulic oil can directly flow to the hydraulic oil tank 1 through the high pressure relief valve 17), oil on the main oil path flows to the third reversing valve 27, meanwhile, the EV5 of the third reversing valve 27 is electrically commutated, the oil enters the test workpiece 31 (plunger cylinder) after ejecting the first hydraulic control one-way valve 28, (the front end of the test workpiece is abutted against the trolley, two hydraulic motors 24A and 24B are arranged below the trolley for driving), at the moment, the test workpiece has no load, the flow of the low pressure pump and the high pressure pump is merged to enter the test workpiece to drive the trolley to rapidly advance, meanwhile, the trolley drives the two hydraulic motors 24A and 24B to forwardly rotate, the servo valve 23 is not electrified, the hydraulic motors are communicated with each other, the oil, the proximity switch 30 detects a signal, the EV8 of the first reversing valve 18 is electrically reversed through electrical control, a part of hydraulic oil in the main oil path jacks the bidirectional hydraulic lock 19 through the first reversing valve 18 to enter rodless cavities of the locking oil cylinders 20A and 20B, an oil cylinder piston rod is pushed forwards, the oil cylinder piston rod is inserted into a positioning hole to lock the trolley, and the test workpiece and the trolley stop advancing simultaneously; (through electric control, the EV8 of the first reversing valve 18 is electrified and loses electricity after a few seconds, the first reversing valve 18 returns to an O-shaped neutral position, and the locking oil cylinder is locked by a bidirectional hydraulic lock 19 for pressure maintaining). At the moment, the trolley is locked, the load at the front end of the test workpiece is increased, the pressure on the main oil circuit is increased continuously, the low-pressure pump overflows after reaching the set pressure, the high-pressure pump pressurizes continuously (the low pressure of the large displacement pump and the high pressure of the small displacement pump reduce the power of the motor), the pressure is detected by the second pressure sensor 25B, all electromagnetic valves are de-energized after delaying for several seconds after reaching the set pressure through electric control, the test workpiece 31 enters a pressure maintaining test state through closing of the first hydraulic control one-way valve 28 and the second hydraulic control one-way valve 29, and the pressure maintaining condition is observed through the third pressure gauge 14C; the hydraulic oil on the main oil way returns to the oil tank through the third reversing valve 27, the oil circulates in a no-load mode, and the system enters a low-energy-consumption state.

2) And (4) finishing the test: the pressure of a test workpiece 31 (plunger cylinder) is relieved, the locking oil cylinder retracts (20A and 20B), the hydraulic motor reversely rotates and retreats (24A and 24B), and the test workpiece 31 retreats and completely retracts (after the test); the method comprises the following specific steps:

and (4) finishing the test: the EV6 of the high-pressure relief valve 17 is electrically commutated, oil on the main oil line flows to the third reversing valve 27, meanwhile, the EV4 of the third reversing valve 27 is electrically commutated, the oil jacks the first hydraulic control one-way valve 28 and the second hydraulic control one-way valve 29, the tested workpiece is decompressed, part of impact is absorbed by the energy accumulator 26, after a few seconds of delay, the EV7 of the first reversing valve 18 is electrically commutated, part of hydraulic oil in the main oil line jacks the bidirectional hydraulic lock 19 through the first reversing valve 18 to enter the rod cavities of the locking oil cylinders 20A and 20B, the piston rods of the oil cylinders are pushed backwards to be separated from the positioning holes, and the workpiece and the trolley are unlocked; (through electric control, the EV7 of the first reversing valve 18 is electrified and loses electricity after a few seconds, the first reversing valve 18 returns to an O-shaped neutral position, a locking oil cylinder is locked and maintained by a bidirectional hydraulic lock 19), meanwhile, the EV3 of a servo valve 23 is electrified, the servo state of a hydraulic motor is closed, then the EV1 of a second reversing valve 21 is electrified, a part of hydraulic oil in a main oil path jacks a bidirectional overflow valve 22 through the second reversing valve 21, enters the hydraulic motors 24A and 24B to control the motor to rotate reversely, a trolley is driven to move backwards, and meanwhile, a test workpiece returns until the workpiece is completely retracted. The pressures of the hydraulic motors 24A and 24B are set by the two-way relief valve 22, the pressures are detected by the first pressure sensor 25A, and the pressure sensors are electrically controlled to be associated with the high-pressure relief valve 17, so that abnormal direct pressure relief is realized, and the safety of the hydraulic motors is ensured.

During manual control: electromagnets EV1 and EV2 of the second reversing valve 21 are powered on, EV3 of the servo valve 23 is powered on, the hydraulic motor can be manually controlled to rotate positively and negatively, the trolley is driven to move back and forth, and the purpose of placing test workpieces is achieved.

The plunger cylinder testing hydraulic system in the embodiment can reduce the energy consumption of the system, adopts a double-motor return driving mode, reduces system faults, meets the operation requirements, integrates the hydraulic system, improves the oil liquid filtering precision, and enables the hydraulic system to be more reliable and stable; the hydraulic system has compact structure, low equipment cost and high working efficiency.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.