A high-precision test bench for detecting internal leakage of hydraulic cylinders

Abstract

The present invention provides a high-precision test bench for detecting leakage in a hydraulic cylinder. It includes a hydraulic cylinder circuit, a hydraulic oil heating circuit, a cooling water circuit and a loading cylinder circuit; the piston rod of the loading cylinder is connected to the piston rod of the hydraulic cylinder through a connecting tool; the hydraulic oil heating circuit includes a heating oil pump, a solenoid valve A and a safety valve; the oil outlet of the heating oil pump is connected to the oil inlet of the solenoid valve A; the oil outlet of the solenoid valve A returns oil to the hydraulic oil tank; the safety valve is arranged between the heating oil pump and the solenoid valve A. The present invention adopts an oil temperature control system composed of a hydraulic oil heating circuit and a cooling water circuit, and the temperature error can be controlled within ±2°C. It can meet the measurement of the bulk elastic modulus K of the hydraulic oil at different temperatures, and improves the calibration accuracy of the elastic modulus K of the hydraulic oil and the leakage detection accuracy of the hydraulic cylinder to be tested. By setting a loading cylinder circuit to adjust the pressure of the hydraulic cylinder, it can meet the measurement of the bulk elastic modulus K of the hydraulic oil at different pressures.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic testing, and in particular to a high-precision detection test bench for internal leakage of a hydraulic cylinder. Background Art

[0002] The pressure drop method is used to detect leakage in hydraulic cylinders. The commonly used method is to take the hydraulic oil elastic modulus K as an empirical value. In actual measurement, the hydraulic oil elastic modulus K is affected by temperature, pressure, etc. The existing detection device has the defects of low detection accuracy, single function, high production cost, etc. It is impossible to calibrate the hydraulic oil bulk elastic modulus K at different temperatures and pressures.

[0003] In summary, there is an urgent need for a high-precision hydraulic cylinder internal leakage detection test bench to solve the problems existing in the prior art. Summary of the invention

[0004] The present invention aims to provide a high-precision test bench for detecting internal leakage of a hydraulic cylinder, so as to solve the problem of measuring the elastic modulus K of the hydraulic oil and the like.

[0005] To achieve the above-mentioned purpose, the present invention provides a high-precision detection test bench for internal leakage of a hydraulic cylinder, comprising a hydraulic cylinder circuit, a hydraulic oil heating circuit and a cooling water circuit;

[0006] The hydraulic cylinder circuit includes a hydraulic cylinder, an electromagnetic reversing valve A, a proportional flow cartridge valve and an oil pump A; the oil outlet of the oil pump A is connected to the oil inlet of the proportional flow cartridge valve, the oil outlet of the proportional flow cartridge valve is connected to the oil inlet of the electromagnetic reversing valve A, the two oil ports on the electromagnetic reversing valve A are connected to the corresponding oil ports on the hydraulic cylinder through the stop valve A and the stop valve B respectively, and the oil return ports of the electromagnetic reversing valve A and the proportional flow cartridge valve are both connected to the hydraulic oil tank; a filter and a heat exchanger are sequentially arranged on the oil circuit between the oil return port of the electromagnetic reversing valve A and the hydraulic oil tank;

[0007] The hydraulic oil heating circuit includes a heating oil pump, a solenoid valve A and a safety valve; the oil outlet of the heating oil pump is connected to the oil inlet of the solenoid valve A; the oil outlet of the solenoid valve A returns oil to the hydraulic oil tank; the safety valve is arranged between the heating oil pump and the solenoid valve A;

[0008] The cooling water circuit includes a cooling water pump, a stop valve C, a solenoid valve B, a solenoid valve C and a one-way valve; the water outlet of the cooling water pump is connected to the water inlet of the stop valve C; the water outlet of the stop valve C is connected to the water inlets of the solenoid valve B and the solenoid valve C respectively, the water outlet of the solenoid valve B is connected to the heat exchanger on the hydraulic cylinder circuit, and the water outlet of the solenoid valve C returns water to the cooling water tank; the one-way valve is arranged between the water outlets of the solenoid valve B and the solenoid valve C.

[0009] Preferably, a group of pressure sensor A and temperature sensor B for detecting oil circuit pressure and temperature are respectively provided on the two oil ports of the hydraulic cylinder.

[0010] Preferably, the hydraulic cylinder and the stop valve A, and the hydraulic cylinder and the stop valve B are connected by hydraulic steel pipes.

[0011] Preferably, a cartridge-type pressure reducing valve for adjusting the pressure and a pressure sensor B for detecting the pressure are provided between the oil outlet of the oil pump A and the oil inlet of the proportional flow cartridge valve.

[0012] Preferably, a proportional overflow valve and a temperature sensor B for detecting temperature are respectively provided between the oil outlet of the proportional flow cartridge valve and the oil inlet of the electromagnetic reversing valve A.

[0013] Furthermore, the present invention also includes a loading cylinder circuit; the loading cylinder circuit includes a loading cylinder, a relief valve, a cartridge valve assembly and an oil pump B; the piston rod of the loading cylinder is connected to the piston rod of the hydraulic cylinder through a connecting tool; the cartridge valve assembly includes a two-way cartridge valve A and a two-way cartridge valve B respectively connected to the oil outlet of the oil pump B, and a two-way cartridge valve C and a two-way cartridge valve D respectively connected to the two oil ports of the loading cylinder for oil discharge; the inlet of the relief valve is respectively connected to the outlet of the two-way cartridge valve C and the two-way cartridge valve D, and the outlet of the relief valve is connected to the hydraulic oil tank.

[0014] Preferably, a force sensor and a grating displacement sensor are installed on the connecting tool;

[0015] Preferably, the loading cylinder circuit also includes an electromagnetic reversing valve B; the two oil ports of the electromagnetic reversing valve B are connected to the corresponding oil ports on the loading cylinder; the two oil ports of the loading cylinder are respectively provided with a pressure sensor C and a pressure sensor D for detecting the oil circuit pressure.

[0016] Preferably, the filter is a tubular oil return filter.

[0017] Preferably, the heat exchanger is a plate heat exchanger.

[0018] The application of the technical solution of the present invention has the following beneficial effects:

[0019] (1) In the present invention, considering that the elastic modulus K of the hydraulic oil is affected by different influencing factors, including system working pressure, oil temperature, different types of oil, amount of air mixed in, etc., the actual measured value is used in this scheme to calibrate the elastic modulus K of the hydraulic oil.

[0020] (2) In the present invention, in order to improve the calibration accuracy of the elastic modulus K of the hydraulic oil and the leakage detection accuracy of the hydraulic cylinder to be tested, the internal leakage of the calibration cylinder and the stop valve used in the calibration system is zero. At the same time, the hydraulic system connection parts that affect the accuracy of the results are connected by hydraulic steel pipes to improve the accuracy. The wall thickness of the hydraulic steel pipe is ≥3mm.

[0021] (3) In the present invention, a high-precision hydraulic oil temperature control system consisting of a hydraulic oil heating circuit and a cooling water circuit is used, and the temperature error can be controlled within ±2°C. This can meet the measurement of the hydraulic oil bulk elastic modulus K at different temperatures, and improve the calibration accuracy of the hydraulic oil elastic modulus K and the leakage detection accuracy of the hydraulic cylinder to be tested.

[0022] (4) In the present invention, the pressure in the calibrated hydraulic cylinder can be adjusted to the required pressure (0-35MPa) through the hydraulic cylinder circuit, and then the calibrated hydraulic cylinder is loaded by the loading cylinder, so that the bulk elastic modulus K of the hydraulic oil can be measured under different pressures, thereby improving the calibration accuracy of the hydraulic oil elastic modulus K and the leakage detection accuracy in the hydraulic cylinder to be tested.

[0023] (5) In the present invention, in order to improve the calibration accuracy of the elastic modulus K of the hydraulic oil and the leakage detection accuracy of the hydraulic cylinder to be tested, a grating scale displacement sensor is used in the connecting fixture, and the accuracy can reach 0.001mm.

[0024] (6) The high-precision hydraulic cylinder internal leakage detection test bench of the present invention is a multifunctional hydraulic cylinder detection test bench, which can carry out hydraulic cylinder trial operation, starting pressure characteristic test, stroke test, leakage test, high temperature test, pressure resistance test, load efficiency test, etc. It has wide application and strong practicality.

[0025] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 This is the hydraulic principle diagram of the high-precision test bench for detecting leakage in the pressure cylinder;

[0028] Figure 2 It is a schematic diagram of the internal leakage process;

[0029] Among them, 1. Hydraulic cylinder, 2.1. Temperature sensor A, 2.2. Temperature sensor B, 3.1. Pressure sensor A, 3.2. Pressure sensor B, 3.3. Pressure sensor C, 3.4. Pressure sensor D, 4.1. Stop valve A, 4.2. Stop valve B, 4.3. Stop valve C, 5. Proportional flow cartridge valve, 6. Proportional relief valve, 7. Cartridge pressure reducing valve, 8. Connecting tooling, 9. Loading cylinder, 10.1. Solenoid reversing valve A, 10.2. Solenoid reversing valve B, 11.1, two-way cartridge valve A, 11.2, two-way cartridge valve B, 11.3, two-way cartridge valve C, 11.4, two-way cartridge valve D, 12, overflow valve, 13.1, hydraulic oil pump, 13.2, cooling water pump, 14.1, solenoid valve A, 14.2, solenoid valve B, 14.3, solenoid valve C, 15, safety valve, 16, filter, 17, heat exchanger, 18, one-way valve, 19, hydraulic oil tank, 20, cooling water tank, 21.1, oil pump A, 21.2, oil pump B. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0031] Embodiment 1:

[0032] See also Figure 1 , Figure 2 , a high-precision detection test bench for internal leakage of a hydraulic cylinder, comprising a hydraulic cylinder circuit, a hydraulic oil heating circuit and a cooling water circuit;

[0033] The hydraulic cylinder circuit includes a hydraulic cylinder 1, an electromagnetic reversing valve A10.1, a proportional flow cartridge valve 5 and an oil pump A21.1; the oil outlet of the oil pump A21.1 is connected to the oil inlet of the proportional flow cartridge valve 5, the oil outlet of the proportional flow cartridge valve 5 is connected to the oil inlet of the electromagnetic reversing valve A10.1, the two oil ports on the electromagnetic reversing valve A10.1 are connected to the corresponding oil ports on the hydraulic cylinder 1 through the stop valve A4.1 and the stop valve B4.2 respectively, and the oil return ports of the electromagnetic reversing valve A10.1 and the proportional flow cartridge valve 5 are both connected to the hydraulic oil tank 19; a filter 16 and a heat exchanger 17 are arranged in sequence on the oil circuit between the oil return port of the electromagnetic reversing valve A10.1 and the hydraulic oil tank 19;

[0034] The hydraulic oil heating circuit includes a heating oil pump 13.1, a solenoid valve A14.1 and a safety valve 15; the oil outlet of the heating oil pump 13.1 is connected to the oil inlet of the solenoid valve A14.1; the oil outlet of the solenoid valve A14.1 returns oil to the hydraulic oil tank 19; the safety valve 15 is arranged between the heating oil pump 13.1 and the solenoid valve A14.1;

[0035] The cooling water circuit includes a cooling water pump 13.2, a stop valve C4.3, a solenoid valve B14.2, a solenoid valve C14.3 and a one-way valve 18; the water outlet of the cooling water pump 13.2 is connected to the water inlet of the stop valve C4.3; the water outlet of the stop valve C4.3 is connected to the water inlets of the solenoid valve B14.2 and the solenoid valve C14.3 respectively, the water outlet of the solenoid valve B14.2 is connected to the heat exchanger on the hydraulic cylinder circuit, and the water outlet of the solenoid valve C14.3 returns water to the cooling water tank; the one-way valve 18 is arranged between the water outlets of the solenoid valve B14.2 and the solenoid valve C14.3; a total of two solenoid valves are arranged on the cooling water circuit, and whether the cooling water flows into the heat exchanger can be controlled by the two solenoid valves, so as to facilitate the switching of the working state of the heat exchanger.

[0036] A set of pressure sensor A3.1 and temperature sensor B2.1 for detecting oil circuit pressure and temperature are respectively provided on the two oil passage ports of the hydraulic cylinder 1;

[0037] A cartridge pressure reducing valve 7 for adjusting pressure and a pressure sensor B3.2 for detecting pressure are provided between the oil outlet of the oil pump A21.1 and the oil inlet of the proportional flow cartridge valve 5. The proportional flow cartridge valve 5 can adjust the flow of the oil circuit. By providing the cartridge pressure reducing valve 7, it is convenient to adjust the oil circuit pressure and ensure the safety of the oil circuit.

[0038] A proportional relief valve 6 and a temperature sensor B2.2 for detecting temperature are arranged between the oil outlet of the proportional flow cartridge valve 5 and the oil inlet of the electromagnetic reversing valve A10.1. The proportional relief valve 6 can play the role of constant pressure relief, pressure stabilization, system unloading and safety protection.

[0039] It also includes a loading cylinder circuit; the loading cylinder circuit includes a loading cylinder 9, a relief valve 12, a cartridge valve assembly and an oil pump B21.2; the piston rod of the loading cylinder 9 is connected to the piston rod of the hydraulic cylinder 1 through a connecting tool 8; the cartridge valve assembly includes a two-way cartridge valve A11.1 and a two-way cartridge valve B11.2 respectively connected to the oil outlet of the oil pump B21.2, and a two-way cartridge valve C11.3 and a two-way cartridge valve D11.4 respectively connected to the two oil ports of the loading cylinder 9 for oil discharge; the inlet of the relief valve 12 is respectively connected to the outlet of the two-way cartridge valve C11.3 and the two-way cartridge valve D11.4, and the outlet of the relief valve 12 is connected to the hydraulic oil tank 19.

[0040] Four two-way cartridge valves are used to form a bridge circuit and a relief valve, and the overall structure is scientific, easy to install and adjust, and the cost is low. In this embodiment, the output oil pressure of the oil pump A21.1 and the oil pump B21.2 are both 35MPa.

[0041] The loading cylinder circuit also includes an electromagnetic reversing valve B10.2; the two oil ports of the electromagnetic reversing valve B10.2 are connected to the corresponding oil ports on the loading cylinder 9; the two oil ports of the loading cylinder 9 are respectively provided with a pressure sensor C3.3 and a pressure sensor D3.4 for detecting the oil circuit pressure.

[0042] The filter 16 is a tubular return oil filter, which can intercept impurities in the return oil to ensure the normal operation of the hydraulic system.

[0043] The heat exchanger 17 is a plate heat exchanger, which has a simple structure and high heat transfer efficiency.

[0044] The present invention provides a hydraulic oil heating circuit and a cooling water circuit for regulating the temperature of the hydraulic oil, and its working principle is as follows: when heating the hydraulic oil, the heating oil pump 13.1 is started, so that the hydraulic oil in the hydraulic oil tank 19 can circulate in the hydraulic oil heating circuit, and the kinetic energy is converted into thermal energy through the overflow of the safety valve 15 to achieve overflow heating of the hydraulic oil. When the temperature of the hydraulic oil is too high, the cooling water circuit can be connected to the heat exchanger 17 through the solenoid valve B14.2, and the cooling water pump 13.2 pumps the cooling water in the cooling water tank 20 into the heat exchanger 17. When the temperature of the hydraulic oil is too low, the cooling water circuit can be disconnected from the heat exchanger 17 through the solenoid valve B14.2 to prevent the cooling water from entering the heat exchanger 17. In addition, when the heat exchanger 17 is blocked, the cooling water flowing to the heat exchanger 17 can flow back into the cooling water tank 20 through the one-way valve 18, reducing the possibility of damage to the solenoid valve B14.2 and ensuring reliable use.

[0045] The above-mentioned high-precision test bench for detecting leakage in hydraulic cylinder is used for determining the elastic modulus K of hydraulic oil: Figure 1 As shown, hydraulic cylinder 1 is the calibration cylinder, the internal leakage of hydraulic cylinder 1 and stop valve A4.1 and stop valve B4.2 is zero, and the calibration cylinder is connected to stop valve A4.1 and stop valve B4.2 with hydraulic steel pipes. Before the test, the hydraulic oil temperature is controlled at the set value (the temperature error can be controlled within ±2°C), the calibration cylinder is tested several times, the calibration cylinder piston is moved to the end, the pressure in the calibration cylinder is adjusted to the required pressure (can be adjusted between 0-35MPa), the stop valve A4.1 is closed, and the load is loaded through the loading cylinder circuit, and the elastic modulus K of the hydraulic oil is calculated according to the formula: V can be calculated based on the geometric dimensions of the calibration cylinder and hydraulic steel pipe. The pressure change is read by the pressure sensor, and the volume change is calculated by reading the stroke change by the grating scale displacement sensor. Thus, the elastic modulus of the hydraulic oil at different temperatures and pressures can be calculated. The inner diameter of the calibration cylinder is ≤40mm, and the stroke is 500mm.

[0046] The working process of the hydraulic cylinder internal leakage high-precision detection test bench for the hydraulic cylinder internal leakage detection to be tested is as follows:

[0047] like Figure 1 As shown, the hydraulic cylinder 1 is the hydraulic cylinder to be tested, and the hydraulic cylinder to be tested is not connected to the loading cylinder. The hydraulic cylinder to be tested is tested several times, the piston of the hydraulic cylinder to be tested is moved to the end, and the pressure in the hydraulic cylinder to be tested is adjusted to the required pressure (adjustable between 0-35MPa). If the hydraulic cylinder to be tested is moved to the rightmost end, the stop valve A4.1 is closed, and the pressure and temperature values ​​are read through the pressure sensor A3.1 and the temperature sensor A2.1. Because the bulk elastic modulus K of the hydraulic oil has been calibrated at different pressures and temperatures, the value can be directly taken. The specific detection and calculation process of internal leakage is as follows:

[0048] According to the measured pressure drop value, Figure 2 The relationship between the pressure drop and the internal leakage value at the calculation point shown in the principle is assumed to be filled with pressure oil with a volume of V1 and a pressure of p1 into the rodless chamber of the hydraulic cylinder without displacement of the piston rod. After a period of time t, the leakage amount is V L At this time, the oil pressure in the rodless chamber of the hydraulic cylinder is p2 and the volume is V2, and the internal leakage volume V L Volume V at pressure p2 L0 =V2-V1. Use V L1 Indicates the volume V at pressure p2 L0 The volume of oil under standard atmospheric pressure. The internal leakage is recorded as Q L .

[0049] According to the elastic modulus of the oil We can get:

[0050]

[0051]

[0052] From the above two formulas, we can get:

[0053]

[0054]

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-precision test bench for detecting internal leakage of hydraulic cylinders, characterized in that: Including hydraulic cylinder circuit, hydraulic oil heating circuit and cooling water circuit; The hydraulic cylinder circuit comprises a hydraulic cylinder (1), an electromagnetic reversing valve A (10.1), a proportional flow cartridge valve (5) and an oil pump A (21.1); the oil outlet of the oil pump A (21.1) is connected to the oil inlet of the proportional flow cartridge valve (5), the oil outlet of the proportional flow cartridge valve (5) is connected to the oil inlet of the electromagnetic reversing valve A (10.1), the two oil ports on the electromagnetic reversing valve A (10.1) are respectively connected to the corresponding oil ports on the hydraulic cylinder (1) through the stop valve A (4.1) and the stop valve B (4.2), and the oil return ports of the electromagnetic reversing valve A (10.1) and the proportional flow cartridge valve (5) are both connected to the hydraulic oil tank (19); a filter (16) and a heat exchanger (17) are provided in sequence on the oil circuit between the oil return port of the electromagnetic reversing valve A (10.1) and the hydraulic oil tank (19); The hydraulic oil heating circuit comprises a heating oil pump (13.1), a solenoid valve A (14.1) and a safety valve (15); the oil outlet of the heating oil pump (13.1) is connected to the oil inlet of the solenoid valve A (14.1); the oil outlet of the solenoid valve A (14.1) returns oil to the hydraulic oil tank (19); the safety valve (15) is arranged between the heating oil pump (13.1) and the solenoid valve A (14.1); The cooling water circuit comprises a cooling water pump (13.2), a stop valve C (4.3), a solenoid valve B (14.2), a solenoid valve C (14.3) and a one-way valve (18); the water outlet of the cooling water pump (13.2) is connected to the water inlet of the stop valve C (4.3); the water outlet of the stop valve C (4.3) is connected to the water inlets of the solenoid valve B (14.2) and the solenoid valve C (14.3) respectively, the water outlet of the solenoid valve B (14.2) is connected to the heat exchanger on the hydraulic cylinder circuit, and the water outlet of the solenoid valve C (14.3) returns water to the cooling water tank; the one-way valve (18) is arranged between the water outlets of the solenoid valve B (14.2) and the solenoid valve C (14.3); A set of pressure sensors A (3.1) and temperature sensors A (2.1) for detecting oil circuit pressure and temperature are respectively provided on two oil passages of the hydraulic cylinder (1); It also includes a loading cylinder circuit; the loading cylinder circuit includes a loading cylinder (9), a relief valve (12), a cartridge valve assembly and an oil pump B (21.2); the piston rod of the loading cylinder (9) is connected to the piston rod of the hydraulic cylinder (1) through a connecting tool (8); the cartridge valve assembly includes a two-way cartridge valve A (11.1) and a two-way cartridge valve B (11.2) respectively connected to the oil outlet of the oil pump B (21.2), and a two-way cartridge valve C (11.3) and a two-way cartridge valve D (11.4) respectively connected to the two oil outlets of the loading cylinder (9) for oil discharge; the inlet of the relief valve (12) is respectively connected to the outlet of the two-way cartridge valve C (11.3) and the outlet of the relief valve (12) is connected to the hydraulic oil tank (19); The connecting tool (8) is equipped with a force sensor and a grating displacement sensor; The loading cylinder circuit further comprises an electromagnetic reversing valve B (10.2); two oil passages of the electromagnetic reversing valve B (10.2) are connected to corresponding oil passages on the loading cylinder (9); and a pressure sensor C (3.3) and a pressure sensor D (3.4) for detecting oil circuit pressure are respectively provided on the two oil passages of the loading cylinder (9); The heat exchanger (17) is a plate heat exchanger.

2. A high-precision hydraulic cylinder internal leakage detection test bench according to claim 1, characterized in that: The hydraulic cylinder (1) and the stop valve A (4.1), and the hydraulic cylinder (1) and the stop valve B (4.2) are connected by hydraulic steel pipes.

3. A high-precision hydraulic cylinder internal leakage detection test bench according to claim 2, characterized in that: A cartridge-type pressure reducing valve (7) for adjusting pressure and a pressure sensor B (3.2) for detecting pressure are provided between the oil outlet of the oil pump A (21.1) and the oil inlet of the proportional flow cartridge valve (5).

4. A high-precision hydraulic cylinder internal leakage detection test bench according to claim 3, characterized in that: A proportional overflow valve (6) and a temperature sensor B (2.2) for detecting temperature are respectively provided between the oil outlet of the proportional flow cartridge valve (5) and the oil inlet of the electromagnetic reversing valve A (10.1).

5. The high-precision hydraulic cylinder internal leakage detection test bench according to claim 1 is characterized in that: Said The filter (16) is a tubular return oil filter.

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