A test device capable of measuring the friction force and contact pressure of seals during entry and exit

Abstract

The present invention discloses a test device capable of measuring the friction force and contact pressure of a seal entry and exit stroke, comprising: a reciprocating drive system, a force sensor, a test cylinder, a piston rod and a pressure module; one end of the reciprocating drive system is connected to the force sensor; the other end of the force sensor is connected to the piston rod; the test cylinder comprises a first cylinder body, a second cylinder body, a first end cover, a second end cover, a first bushing and a second bushing; the first cylinder body is connected to the second cylinder body, and the piston rod passes through the first cylinder body and the second cylinder body; the first bushing is arranged between the test cylinder and the piston rod; the second bushing is arranged between the test cylinder and the piston rod; the test cylinder is connected to the pressure module; the first piston rod seal and the second piston rod seal are arranged on the contact surfaces of the first end cover, the second end cover and the piston rod; the seal to be tested is arranged on the contact surface of the second bushing and the piston rod; the implementation of the present invention can accurately and truly measure the friction force of the seal entry and exit stroke.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic reciprocating seals, and in particular to a test device capable of measuring friction force and contact pressure of an entry and exit stroke of a seal. Background Art

[0002] Seals are the most basic device to ensure the normal operation of hydraulic systems. Most leakage in hydraulic systems is caused by seal failure. Once a seal fails, not only will the volumetric efficiency of the system be reduced, but in severe cases, the system will not be able to work due to the inability to build up pressure. External leakage will also pollute the environment. For dynamic seals in reciprocating seals, the main failure form is wear failure. Therefore, obtaining the full-cycle evolution law of seal friction performance is of great significance to ensure the normal operation of hydraulic systems.

[0003] Under actual working conditions, the seal faces low pressure during the outward stroke and high pressure during the inward stroke. However, most of the existing reciprocating seal test platforms make the cylinder body into a through cavity. The seal under this test platform structure is subjected to the same system pressure during the outward stroke and the inward stroke, making the measured test value not authentic. Therefore, how to accurately and truly measure the friction force of the seal during the inward and outward strokes is an urgent problem to be solved. Summary of the invention

[0004] The embodiment of the present invention provides a test device capable of measuring the friction force and contact pressure of a seal during its entry and exit stroke, and can accurately and truly measure the friction force of a seal during its entry and exit stroke.

[0005] An embodiment of the present invention provides a test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes, comprising:

[0006] One end of the reciprocating drive system is connected to a force sensor; the other end of the force sensor is connected to a piston rod; the test cylinder comprises a first cylinder body, a second cylinder body, a first end cover, a second end cover, a first bushing and a second bushing; the first cylinder body is connected to the second cylinder body; the piston rod passes through the first cylinder body and the second cylinder body; the first bushing is arranged between the test cylinder and the piston rod; the second bushing is arranged between the test cylinder and the piston rod; the test cylinder is connected to a pressure module; the first piston rod seal and the second piston rod seal are arranged on the contact surfaces of the first end cover, the second end cover and the piston rod; the seal to be tested is arranged on the contact surface of the second bushing and the piston rod;

[0007] The reciprocating drive system is used to drive the piston rod to perform reciprocating motion;

[0008] The pressure module is used to adjust the pressure in the cavity of the first cylinder and the pressure in the cavity of the second cylinder to the first pressure, the second pressure and the external environment pressure respectively when the piston rod is not in contact with the first bushing and the second bushing; when the piston rod is in contact with the first bushing and the second bushing, the pressure in the cavity of the first cylinder is adjusted to the first pressure and the second pressure respectively, and the pressure in the cavity of the second cylinder is adjusted to the external environment pressure; wherein the first pressure is less than the second pressure;

[0009] The force sensor is used to measure the first friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the first pressure when the piston rod is not in contact with the first bushing and the second bushing, measure the second friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the second pressure, and measure the third friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the external ambient pressure; when the piston rod is in contact with the first bushing and the second bushing, measure the fourth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the out-stroke under the first pressure, and measure the fifth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the in-stroke under the second pressure.

[0010] Furthermore, the first cylinder body is provided with a first oil inlet and a first oil outlet; the second cylinder body is provided with a second oil inlet and a second oil outlet;

[0011] The pressure module includes: an oil tank, a liquid level gauge, a breathing filter, an oil drain switch, a first oil suction filter, a second oil suction filter, an oil return filter, a first oil suction switch, a second oil suction switch, a first air drive pump, a second air drive pump, a first pressure maintaining switch, a second pressure maintaining switch, a first pressure relief switch, a second pressure relief switch, a first pressure sensor, and a second pressure sensor;

[0012] The liquid level meter, breathing filter and oil drain switch are installed on the oil tank;

[0013] One end of the return oil filter is connected to the oil tank; the other end of the return oil filter is connected to the second oil outlet via the first pressure relief switch, and is connected to the first oil outlet via the second pressure relief switch;

[0014] One end of the first oil suction filter is connected to the oil tank, the other end of the first oil suction filter is connected to the first oil suction switch, the other end of the first oil suction switch is connected to the first air drive pump, the other end of the first air drive pump is connected to the first pressure maintaining switch, the other end of the first pressure maintaining switch is connected to the first oil inlet, and a first pressure sensor is provided on the pipeline connecting the first pressure maintaining switch and the first oil inlet;

[0015] One end of the second oil suction filter is connected to the oil tank, the other end of the second oil suction filter is connected to the second oil suction switch, the other end of the second oil suction switch is connected to the second air drive pump, the other end of the second air drive pump is connected to the second pressure maintaining switch, the other end of the second pressure maintaining switch is connected to the second oil inlet, and a second pressure sensor is provided on the pipeline connecting the second pressure maintaining switch and the second oil inlet;

[0016] The first pressure sensor is used to measure the pressure in the cavity of the first cylinder;

[0017] The second pressure sensor is used to measure the pressure in the cavity of the second cylinder.

[0018] Furthermore, the pressure module further includes: an air source, an air circuit switch, a triplet, a first pressure reducing valve, a second pressure reducing valve, a third pressure sensor and a fourth pressure sensor;

[0019] The triple piece is composed of an air filter, a pressure reducing valve and an oil mist collector connected in sequence;

[0020] One end of the air circuit switch is connected to the air source; the other end of the air circuit switch is connected to the triplex; the other end of the triplex is connected to the first air drive pump via a first pressure reducing valve, and is connected to the second air drive pump via a second pressure reducing valve; a third pressure sensor is provided on the pipeline connecting the first pressure reducing valve and the first air drive pump; a fourth pressure sensor is provided on the pipeline connecting the second pressure reducing valve and the second air drive pump.

[0021] Furthermore, it also includes: a thin film pressure sensor, a watertight connector and a contact pressure measuring unit;

[0022] The thin film pressure sensor is arranged on the contact surface between the seal to be tested and the second bushing; the thin film pressure sensor is connected to the contact pressure measuring unit via a watertight connector;

[0023] The thin film pressure sensor is used to measure the third pressure generated by the seal to be tested and the second bushing being squeezed by the piston rod when the piston rod contacts the first bushing and the second bushing;

[0024] The watertight connector is used to transmit the received third pressure to the contact force measuring unit;

[0025] The contact pressure measuring unit is used to generate the contact pressure between the seal to be tested and the piston rod after amplifying, filtering and modulating the third pressure.

[0026] Furthermore, the test cylinder also includes: a dust ring and a guide ring;

[0027] The first end cover and the second end cover are both provided with through holes; the piston rod passes through the first end cover and the second end cover;

[0028] The first end cover is connected to one end of the first cylinder body; the second end cover is connected to one end of the second cylinder body;

[0029] The dust ring and the guide ring are respectively arranged on the contact surface between the first end cover and the piston rod, and the contact surface between the second end cover and the piston rod;

[0030] The dust ring is used to prevent contaminants that fall on the piston rod from entering the oil when the piston rod is retracted;

[0031] The guide ring is used to maintain uniform clearances between the piston rod and the first end cover and the second end cover.

[0032] Further, it also includes: a flange;

[0033] The flange is used to connect the force sensor with the reciprocating drive system and the force sensor with the piston rod.

[0034] Furthermore, the piston rod is a stepped shaft type piston rod.

[0035] Furthermore, the first piston rod seal and the second piston rod seal are symmetrical seal structures.

[0036] Further, the reciprocating drive system comprises: an electric cylinder and an electric cylinder support platform;

[0037] The electric cylinder is installed on the electric cylinder supporting platform.

[0038] The following beneficial effects are achieved by implementing the present invention:

[0039] The present invention provides a test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes. The test device is connected to a force sensor through a reciprocating drive system, and the force sensor is connected to a piston rod. The piston rod passes through a first cylinder body and a second cylinder body of a test cylinder. A first piston rod seal and a second piston rod seal are arranged between a first end cover, a second end cover and the piston rod. A first bushing is arranged between the test cylinder and the piston rod, and a second bushing is arranged between the test cylinder and the piston rod. A seal to be tested is arranged on a contact surface between the second bushing and the piston rod. The test cylinder is connected to a pressure module. The piston rod is driven to reciprocate in the test cylinder through the reciprocating drive system. When the piston rod is not in contact with the first bushing and the second bushing, the pressure module adjusts the pressure in the cavity of the first cylinder body and the pressure in the cavity of the second cylinder body to a first pressure, a second pressure and an external environmental pressure respectively. The contact between the piston rod and the first piston rod seal and the second piston rod seal during the entry and exit strokes under each pressure is measured through the force sensor. the first friction force, the second friction force and the third friction force generated between the seals; when the piston rod contacts the first bushing and the second bushing, during the outward stroke, the pressure module adjusts the cavity pressure of the first cylinder body to the first pressure, adjusts the cavity pressure of the second cylinder body to the external environment pressure, and measures the fourth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the outward stroke through the force sensor; during the inward stroke, the pressure module adjusts the cavity pressure of the first cylinder body to the second pressure, adjusts the cavity pressure of the second cylinder body to the external environment pressure, and measures the fifth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the inward stroke through the force sensor; wherein, the first pressure is less than the second pressure, and is used to simulate the corresponding high pressure and low pressure conditions under actual working conditions, so that the test environment tends to be real; the user can calculate the friction force of the in and out stroke of the seal to be tested based on the values ​​of each friction force measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a general structural diagram of a test device capable of measuring the friction force of a seal during its entry and exit strokes, provided by one embodiment of the present invention.

[0041] Figure 2 It is a schematic diagram of an assembly of a tooling structure module provided by an embodiment of the present invention.

[0042] Figure 3 It is a structural schematic diagram of a test cylinder provided by an embodiment of the present invention when conducting a preliminary test.

[0043] Figure 4 It is a schematic structural diagram of a test cylinder provided by an embodiment of the present invention when conducting a formal test.

[0044] Figure 5 It is a schematic diagram of a pressure module provided in one embodiment of the present invention.

[0045] Figure 6 It is a partial cross-sectional view of the installation position of a thin film pressure sensor provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 , Figure 2 As shown, the present invention provides a test device capable of measuring the friction force and contact pressure of the seal in and out strokes, comprising: a reciprocating drive system, a force sensor, a test cylinder, a piston rod and a pressure module;

[0048] One end of the reciprocating drive system is connected to a force sensor; the other end of the force sensor is connected to a piston rod; the test cylinder comprises a first cylinder body, a second cylinder body, a first end cover, a second end cover, a first bushing and a second bushing; the first cylinder body is connected to the second cylinder body, and the piston rod passes through the first cylinder body and the second cylinder body; the first bushing is arranged between the first cylinder body and the piston rod; the second bushing is arranged between the second cylinder body and the piston rod; the test cylinder is connected to a pressure module; the first piston rod seal and the second piston rod seal are arranged on the contact surfaces of the first end cover, the second end cover and the piston rod; the seal to be tested is arranged on the contact surface of the second bushing and the piston rod;

[0049] The reciprocating drive system is used to drive the piston rod to perform reciprocating motion;

[0050] The pressure module is used to adjust the pressure in the cavity of the first cylinder and the pressure in the cavity of the second cylinder to the first pressure, the second pressure and the external environment pressure respectively when the piston rod is not in contact with the first bushing and the second bushing; when the piston rod is in contact with the first bushing and the second bushing, the pressure in the cavity of the first cylinder is adjusted to the first pressure and the second pressure respectively, and the pressure in the cavity of the second cylinder is adjusted to the external environment pressure; wherein the first pressure is less than the second pressure;

[0051] The force sensor is used to measure the first friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the first pressure when the piston rod is not in contact with the first bushing and the second bushing, measure the second friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the second pressure, and measure the third friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the external environmental pressure; when the piston rod is in contact with the first bushing and the second bushing, measure the fourth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be measured during the out-stroke under the first pressure, and measure the fifth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be measured during the in-stroke under the second pressure;

[0052] Specifically, the reciprocating drive system 130, the test cylinder 110, the piston rod 117 and the force sensor 135 together constitute the tooling structure module 100; the pressure module 200 is connected to the test cylinder 110; the first cylinder body 118 and the second cylinder body 119 are connected by threads; the entire test cylinder 110 is fixed to the workbench by installing a test cylinder support 122 at the ends of the first cylinder body 118 and the second cylinder body 119; the second bushing 124 is provided with a data line hole inside, which is coaxial with the data line hole of the second cylinder body 119;

[0053] It should be noted that in Figure 2: is a cross-sectional view of the test cylinder of the present application. In actual application, the first cylinder body 118 and the second cylinder body 119 are both cylindrical structures and are connected by threads; the first bushing and the second bushing are respectively arranged between the piston rod 117 and the test cylinder composed of the first cylinder body 118 and the second cylinder body 119. When the first bushing 123 and the second bushing 124 are in contact with the piston rod 117, the first cylinder body 118 and the second cylinder body 119 are unconnected cavities; when the first bushing 123 and the second bushing 124 are not in contact with the piston rod 117, the first cylinder body 118 and the second cylinder body 119 are connected cavities; that is, when the pressure module 200 adjusts the intracavity pressure of the first cylinder body 118 and the second cylinder body 119, when the piston rod 117 is not in contact with the first bushing 123 and the second bushing 124, the first cylinder body 118 and the second cylinder body 119 form a through cavity, which can be understood as the pressure module 200 adjusts the pressure in the through cavity to low pressure (i.e. the above-mentioned first pressure), high pressure (i.e. the above-mentioned second pressure) and external environmental pressure respectively; when the piston rod 117 contacts the first bushing 123 and the second bushing 124, the first cylinder body 118 and the second cylinder body 119 are two independent cylinder bodies respectively, and the pressure module 200 adjusts the cavity pressure of the first cylinder body 118 to low pressure (i.e. the above-mentioned first pressure) and high pressure (i.e. the above-mentioned second pressure), and adjusts the cavity pressure of the second cylinder body 119 to the external environmental pressure; the force sensor 135 is used to measure the sum of the friction forces generated by the seals in contact with the piston rod 117 in the test cylinder 110 under various working conditions, and the user can perform corresponding calculations based on the measurement data of the force sensor 135 under different working conditions to obtain the required friction force of the measured seal; in the actual working process, the user can make corresponding adjustments according to the test requirements under actual working conditions.

[0054] In a preferred embodiment, the reciprocating drive system comprises: an electric cylinder and an electric cylinder support platform; the electric cylinder is mounted on the electric cylinder support platform;

[0055] Specifically, the reciprocating drive system 130 is composed of an electric cylinder support platform 132 for supporting the electric cylinder and an electric cylinder 131 for driving; when the reciprocating drive system 130 is in operation, the electric cylinder in the reciprocating drive system 130 performs reciprocating motion on the electric cylinder support platform, driving the piston rod connected to the reciprocating drive system 130 to perform synchronous reciprocating motion.

[0056] In a preferred embodiment, it further comprises: a flange; the flange is used to connect the force sensor to the reciprocating drive system and to connect the force sensor to the piston rod;

[0057] Specifically, an electric cylinder push rod 133 is provided at one end of the electric cylinder 131 in the reciprocating drive system 130 that is connected to the flange 134 . The electric cylinder push rod 133 is coaxially connected to the flange 134 , the force sensor 135 , and the piston rod 117 .

[0058] In a preferred embodiment, the piston rod is a stepped shaft type piston rod;

[0059] Specifically, the test device adopts a stepped shaft piston rod, which can be used to control whether the piston rod 117 is in contact with the first bushing 123 and the second bushing 124; for example, when the first bushing 123 and the second bushing 124 are between the recessed portion of the stepped piston rod 117, the stepped piston rod 117 does not come into contact with the first bushing 123 and the second bushing 124; when the first bushing 123 and the second bushing 124 are between the raised portion of the stepped piston rod 117, the stepped piston rod 117 comes into contact with the first bushing 123 and the second bushing 124; it should be supplemented that before the reciprocating drive system 130 controls the stepped piston rod 117 to perform reciprocating motion, the stepped piston rod 117 can be adjusted to a suitable position and then the system can be started to control the movement of the stepped piston rod 117; Figure 3 , which is a schematic diagram of a structure in which the recessed portion of a stepped piston rod 117 provided by the present invention is located between the first bushing 123 and the second bushing 124. At this time, when the reciprocating drive system 130 is started, the first bushing 123 and the second bushing 124 do not come into contact with the stepped piston rod 117; Figure 4 The figure is a schematic diagram of the structure in which the raised portion of a stepped piston rod 117 provided by the present invention is located between a first bushing 123 and a second bushing 124 . When the reciprocating drive system 130 is started, the first bushing 123 and the second bushing 124 come into contact with the stepped piston rod 117 .

[0060] It should be noted that the lengths of the structures in the figure are only for illustration and can be adjusted according to actual needs.

[0061] In a preferred embodiment, the first cylinder body is provided with a first oil inlet and a first oil outlet; the second cylinder body is provided with a second oil inlet and a second oil outlet; the pressure module comprises: an oil tank, a liquid level gauge, a breathing filter, an oil drain switch, a first oil suction filter, a second oil suction filter, an oil return filter, a first oil suction switch, a second oil suction switch, a first air drive pump, a second air drive pump, a first pressure maintaining switch, a second pressure maintaining switch, a first pressure relief switch, a second pressure relief switch, a first pressure sensor and a second pressure sensor;

[0062] The liquid level gauge, the breathing filter and the oil drain switch are installed on the oil tank; one end of the return oil filter is connected to the oil tank; the other end of the return oil filter is connected to the second oil outlet via the first pressure relief switch, and is connected to the first oil outlet via the second pressure relief switch; one end of the first suction oil filter is connected to the oil tank, the other end of the first suction oil filter is connected to the first suction oil switch, the other end of the first suction oil switch is connected to the first air drive pump, the other end of the first air drive pump is connected to the first pressure maintaining switch, the other end of the first pressure maintaining switch is connected to the first oil inlet, and a first pressure sensor is provided on the pipeline connecting the first pressure maintaining switch and the first oil inlet; one end of the second suction oil filter is connected to the oil tank, the other end of the second suction oil filter is connected to the second suction oil switch, the other end of the second suction oil switch is connected to the second air drive pump, the other end of the second air drive pump is connected to the second pressure maintaining switch, the other end of the second pressure maintaining switch is connected to the second oil inlet, and a second pressure sensor is provided on the pipeline connecting the second pressure maintaining switch and the second oil inlet; the first pressure sensor is used to measure the pressure in the cavity of the first cylinder; the second pressure sensor is used to measure the pressure in the cavity of the second cylinder;

[0063] Specifically, Figure 2 As shown, the first cylinder 118 and the second cylinder 119 are both single chambers, and the first cylinder 118 is provided with a first oil inlet and a first oil outlet 120; the second cylinder 119 is provided with a second oil inlet and a second oil outlet 121; Figure 5 The figure is a schematic diagram of the structure of a pressure module provided by an embodiment of the present invention. The pressure module 200 is connected to the first cylinder body 118 and the second cylinder body 119 in the test cylinder 110, and is used to provide the cavity pressure of the first cylinder body 118 and the second cylinder body 119 during the test, and then simulate the corresponding cavity pressure in the cavity under actual working conditions, so that the test process and test results tend to be realistic; in the pressure module 200, two sets of independent air-driven pumps are used to output pressure respectively, so as to ensure the stability of the pressure in the cavity of the first cylinder body 118 and the second cylinder body 119.

[0064] The pressure module 200 specifically includes: an oil tank 210, a liquid level gauge 212 and a breathing filter 213 and an oil drain switch 211 installed on the oil tank 210; the oil outlet of the first oil suction filter 214 connected from the oil tank 210 is connected to the oil inlet of the first air drive pump 208 via the first oil suction switch 216; the oil outlet of the first air drive pump 208 is connected to the first oil inlet of the first cylinder 118 via the first pressure maintaining switch 218; a first pressure sensor 220 is provided on the pipeline connecting the first pressure maintaining switch 218 and the first oil inlet for real-time measurement of the intracavity pressure of the first cylinder; the oil outlet of the second oil suction filter 215 connected from the oil tank 210 is connected to the oil inlet of the second air drive pump 209 via the second oil suction switch 217; the oil outlet of the second air drive pump 209 is connected to the second oil inlet of the second cylinder 119 via the second pressure maintaining switch 219; A second pressure sensor 221 is provided on the pipeline connecting the second pressure maintaining switch 219 and the second oil inlet, which is used to measure the intracavity pressure of the second cylinder body in real time; the pressure measuring point (i.e. the above-mentioned first pressure sensor and second pressure sensor) is set on the pipeline connected to the cavity, which can ensure that the measurement data is true and accurate; the pressure provided to the first cylinder body 118 and the second cylinder body 119 is controlled by the pressure module 200, so that the intracavity pressure of the first cylinder body 118 and the intracavity pressure of the second cylinder body 119 required during the test process reach the required pressure of the user during the test process; the first oil outlet 120 of the first cylinder body 118 leads to the pipeline connected to the oil inlet of the return oil filter 224 through the first pressure relief switch 222, and the second oil outlet of the second cylinder body 119 is connected to the oil inlet of the return oil filter 224 through the second pressure relief switch 223.

[0065] In a preferred embodiment, the pressure module further includes: an air source, an air circuit switch, a triplet, a first pressure reducing valve, a second pressure reducing valve, a third pressure sensor and a fourth pressure sensor; the triplet is composed of an air filter, a pressure reducing valve and an oil mist collector connected in sequence; one end of the air circuit switch is connected to the air source; the other end of the air circuit switch is connected to the triplet; the other end of the triplet is connected to the first air drive pump via the first pressure reducing valve, and is connected to the second air drive pump via the second pressure reducing valve; a third pressure sensor is provided on the pipeline connecting the first pressure reducing valve and the first air drive pump; a fourth pressure sensor is provided on the pipeline connecting the second pressure reducing valve and the second air drive pump;

[0066] Specifically, the pressure module 200 also includes an air source 201, which is a low-pressure air source. The air circuit switch 202 is installed at the outlet of the air source 201. The other end of the air circuit switch 202 is connected to a triplet 203, which is composed of an air filter, a pressure reducing valve and an oil mist collector connected in sequence. The air circuit switch 202 is connected to the air filter in the triplet 203, and the oil outlet of the triplet 203 is connected to the oil mist collector. The oil outlet of the triplet 203 is connected to the first air drive pump 208 via the first pressure reducing valve 204, and the oil outlet of the triplet 203 is connected to the second air drive pump 209 via the second pressure reducing valve 205. A third pressure sensor 206 is arranged on the pipeline connecting the first pressure reducing valve 204 and the first air drive pump 208, and a fourth pressure sensor 207 is arranged on the pipeline connecting the second pressure reducing valve 205 and the second air drive pump 209. The third pressure sensor 206 and the fourth pressure sensor 207 are used to measure the pressure on the corresponding pipelines.

[0067] In a preferred embodiment, it also includes: a thin film pressure sensor, a watertight connector and a contact pressure measuring unit; the thin film pressure sensor is arranged on the contact surface between the seal to be tested and the second bushing; the thin film pressure sensor is connected to the contact pressure measuring unit via the watertight connector; the thin film pressure sensor is used to measure the third pressure generated by the seal to be tested and the second bushing being squeezed by the piston rod when the piston rod contacts the first bushing and the second bushing; the watertight connector is used to transmit the received third pressure to the contact pressure measuring unit; the contact force measuring unit is used to generate the contact pressure between the seal to be tested and the piston rod after amplifying and filtering and modulating the third pressure;

[0068] Specifically, Figure 2 , Figure 6 As shown, the thin film pressure sensor 127 of the present invention adopts a PVDF thin film pressure sensor 127, and the PVDF thin film pressure sensor 127 is arranged on the contact surface between the seal 125 to be tested and the groove, and the thin film pressure sensor 127 is connected to the contact pressure measuring unit through the transmission of the watertight connector 128; when the seal 125 to be tested generates contact pressure with the piston rod 117, the thin film pressure sensor 117 is squeezed, and the physical properties of the PVDF thin film pressure sensor 127 are changed due to the squeezing force (that is, the third pressure mentioned above), which is converted into an electrical signal and transmitted to the contact pressure measuring unit through the watertight connector 128. The contact force measuring unit obtains the contact pressure distribution between the seal 125 to be tested and the groove after amplification, filtering and modulation, and then indirectly obtains the contact pressure between the seal 125 to be tested and the piston rod 117.

[0069] In a preferred embodiment, the test cylinder further comprises: a dust ring and a guide ring; the first end cover and the second end cover are both provided with through holes; the piston rod passes through the first end cover and the second end cover; the first end cover is connected to one end of the first cylinder body; the second end cover is connected to one end of the second cylinder body; the dust ring and the guide ring are respectively provided on the contact surface between the first end cover and the piston rod and the contact surface between the second end cover and the piston rod; the dust ring is used to prevent contaminants falling on the piston rod from entering the oil when the piston rod is retracted; the guide ring is used to maintain a uniform gap between the piston rod and the first end cover and the second end cover;

[0070] Specifically, the test cylinder 110 further includes a first end cover 111 and a second end cover respectively installed on both sides of the test cylinder. The first end cover 111 and the second end cover have the same structure, and a through hole is provided on the first end cover 111 and the second end cover, and the piston rod 117 passes through the test cylinder 110 through the through holes on the first end cover 111 and the second end cover; a guide ring 113, a dust ring 112 and a first piston rod seal 114 are provided on the contact surface between the first end cover 111 and the piston rod 117, a first static seal 116 is provided on the contact surface between the first end cover 111 and the second cylinder body 119, and the first end cover 111 and the first cylinder body 119 are provided with a first static seal 116. The contact surface of the test cylinder 18 is also provided with a first seal 116; the contact surfaces of the first bushing 123, the second bushing 124 and the test cylinder 110 are provided with a second static seal; the contact surface of the second end cover and the piston rod 117 is provided with a guide ring 113, a dust ring 112 and a second piston rod seal 115; the dust ring 112 is provided in the device of the present invention, which can prevent contaminants falling on the piston rod 117 from entering the oil provided by the pressure module 200 when the piston rod 117 is retracted; the guide ring 113 is provided to keep the gap between the piston rod 117 and the first end cover 111 and the second end cover uniform.

[0071] In a preferred embodiment, the first piston rod seal and the second piston rod seal are symmetrical seal structures; specifically, the first piston rod seal 114 and the second piston rod seal 115 are symmetrical seals, thereby ensuring that the friction force of the first piston rod seal 114 and the second piston rod seal 115 during the test is basically the same.

[0072] Based on the test device of the present invention, which can measure the friction force and contact pressure of the seal in and out stroke, the friction force of the seal 125 to be tested can be measured in the in and out stroke, which is specifically divided into a formal test and a preliminary test; wherein, Figure 3 As shown, during the formal test, the piston rod 117 is kept in contact with the seal 125 to be tested during the reciprocating motion; Figure 4As shown, during the preparatory test, that is, the piston rod 117 is kept from making contact with the seal 125 to be tested during the reciprocating motion; and whether the piston rod 117 makes contact with the seal 125 to be tested is mainly determined by adjusting the position of the stepped piston rod 117 and the test cylinder 110 before the test. It can be understood that since the stepped piston rod 117 is a piston rod of fixed length, its position before the test can be determined by measuring the length of the stepped piston rod 117 exposed outside the test cylinder 110 before the test, and then controlling whether the stepped piston rod 117 makes contact with the seal 125 to be tested.

[0073] First, a preliminary test is performed. During the preliminary test, the cavities of the first cylinder body 118 and the second cylinder body 119 are connected to form a cavity. The cavity pressure is adjusted to the required pressure through the pressure module 200, and then the friction between the first piston rod seal 114, the second piston rod seal 115 and the piston rod 117 is tested; the test steps here need to be repeated three times, and the cavity pressure is adjusted to the high pressure P u , low pressure P l and external environmental pressure P e ; The high pressure and low pressure referred to here refer to the high and low system pressures to which the seal is subjected in the actual working conditions measured; the sum of the friction forces generated by the first piston rod seal 114, the second piston rod seal 115 and the piston rod 117 under three different pressures is obtained through the force sensor 135; since the first piston rod seal 114 and the second piston rod seal 115 are seals with symmetrical structures, the friction forces of the first piston rod seal 114 and the second piston rod seal 115 in the in-and-out stroke under the same pressure are basically the same; based on the preliminary test, the friction force of a piston rod seal under these three cavity pressures can be obtained, and the specific derivation formula is as follows:

[0074] F u = 1u + 2u

[0075] F l = 1l + 2l

[0076] F e = 1e + 2e

[0077] F 1u = 2u

[0078] F 1l = 2l

[0079] F 1e = 2e

[0080] Among them, F u It means that during the preparatory test stage, the cavity pressure is high pressure P u Force sensor value; F l It means that during the preparatory test stage, the cavity pressure is low pressure P l Force sensor value; F e It means that during the preparatory test stage, the chamber pressure is the external environment pressure P e Force sensor value; F 1u 、F 2u It means that during the preparatory test stage, the cavity pressure is high pressure P u The friction force of the first piston rod seal 114 and the second piston rod seal 115; F 1l 、F 2l It means that during the preparatory test stage, the cavity pressure is low pressure P l The friction force of the first piston rod seal 114 and the second piston rod seal 115 is F 1e 、F 2e It means that during the preparatory test stage, the chamber pressure is the external environment pressure P e The friction force of the first piston rod seal 114 and the second piston rod seal 115 is .

[0081] Secondly, conduct formal tests. When conducting formal tests, Figure 4 As shown, at this time, the cavities of the first cylinder 118 and the second cylinder 119 are not connected; when conducting a formal test, it is necessary to measure twice, and when the friction force of the seal 125 to be tested is entered into the stroke, the cavity pressure of the first cylinder 118 is adjusted to a high pressure P u , adjust the cavity pressure of the second cylinder 119 to the external environment pressure P e When measuring the friction force of the seal 125 to be tested, the cavity pressure of the first cylinder 118 is adjusted to a low pressure P l The pressure in the second cylinder 119 is still adjusted to the external environment pressure P e Then the force sensor 135 in the first cylinder 118 is high pressure P u The value when the first piston rod seal 114 is at high pressure P u The friction force when the second piston rod seal 115 is at the external environment pressure P e The friction force of the force sensor 135 in the first cylinder 118 is low pressure P l The value at this time is equal to the first piston rod seal 114 at low pressure P l The friction force when the second piston rod seal 115 is at the external environment pressure P eThe friction force of the seal 125 to be tested is the sum of the friction force when the piston rod seal 114 is in the stroke and the friction force of the seal 125 to be tested when the piston rod seal 115 is in the stroke; finally, the friction force of the first piston rod seal 114 and the friction force of the second piston rod seal 115 are subtracted from the value of the force sensor 135 to obtain the friction force of the seal 125 to be tested. The specific derivation formula is as follows:

[0082] f o =F o -F l / 2-F e / 2

[0083] f i =F i -F u / 2-F e / 2

[0084] Among them, f o It refers to the friction force of the tested seal 125 when it is out of stroke; f i It refers to the friction force of the seal to be tested when it enters the stroke 125; F o It means that during the formal test phase, the cavity pressure of the first cylinder 118 is low pressure P l The value measured by the force sensor 135 when F i It means that during the formal test phase, the cavity pressure of the first cylinder 118 is high pressure P u The value measured by the force sensor 135.

[0085] It should be noted that the high pressure P u , low pressure P u It refers to the system pressure in the rod chamber of the hydraulic cylinder under actual working conditions, and is also the system pressure on one side of the seal. When the hydraulic cylinder is out of stroke, the rod chamber pressure is less than the rodless chamber pressure, and when it is in stroke, the rod chamber pressure is greater than the rodless chamber pressure, and the rod chamber pressure during the out stroke is less than the rod chamber pressure during the in stroke, so the seal side faces low pressure P during the out stroke. u When entering the stroke, one side of the seal faces high pressure P u ; The external environment pressure P e Refers to the pressure on the other side of the seal under actual working conditions. External environment pressure P e The size of the external pressure varies with different working conditions. Under normal land environment conditions, the external pressure P e is atmospheric pressure; in high-pressure deep-sea environment conditions, the external environmental pressure P e is the sea water pressure.

[0086] By implementing the test device of the present invention that can measure the friction force and contact pressure of the seal in and out stroke, the pressure in the test cylinder cavity can be adjusted according to the pressure module, that is, the performance of the seal under different pressure conditions can be studied; and a thin film pressure sensor is added to the test device of the present invention, and then the seal contact pressure is obtained, thereby increasing the convenience and accuracy of model verification. The present invention has the characteristics of simple structure, reliable function, convenient measurement, etc., and can test the performance of various types of seals.

[0087] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A test device capable of measuring the friction and contact pressure of a seal during its entry and exit strokes, characterized in that: include: Reciprocating drive system, force sensor, test cylinder, piston rod and pressure module; One end of the reciprocating drive system is connected to a force sensor; the other end of the force sensor is connected to a piston rod; the test cylinder comprises a first cylinder body, a second cylinder body, a first end cover, a second end cover, a first bushing and a second bushing; the first cylinder body is connected to the second cylinder body; the piston rod passes through the first cylinder body and the second cylinder body; the first bushing is arranged between the test cylinder and the piston rod; the second bushing is arranged between the test cylinder and the piston rod; the test cylinder is connected to a pressure module; the first piston rod seal and the second piston rod seal are arranged on the contact surfaces of the first end cover, the second end cover and the piston rod; the seal to be tested is arranged on the contact surface of the second bushing and the piston rod; The first cylinder body is provided with a first oil inlet and a first oil outlet; the second cylinder body is provided with a second oil inlet and a second oil outlet; The pressure module includes: an oil tank, a liquid level gauge, a breathing filter, an oil drain switch, a first oil suction filter, a second oil suction filter, an oil return filter, a first oil suction switch, a second oil suction switch, a first air drive pump, a second air drive pump, a first pressure maintaining switch, a second pressure maintaining switch, a first pressure relief switch, a second pressure relief switch, a first pressure sensor, and a second pressure sensor; The liquid level meter, breathing filter and oil drain switch are installed on the oil tank; One end of the return oil filter is connected to the oil tank; the other end of the return oil filter is connected to the second oil outlet via the first pressure relief switch, and is connected to the first oil outlet via the second pressure relief switch; One end of the first oil suction filter is connected to the oil tank, the other end of the first oil suction filter is connected to the first oil suction switch, the other end of the first oil suction switch is connected to the first air drive pump, the other end of the first air drive pump is connected to the first pressure maintaining switch, the other end of the first pressure maintaining switch is connected to the first oil inlet, and a first pressure sensor is provided on the pipeline connecting the first pressure maintaining switch and the first oil inlet; One end of the second oil suction filter is connected to the oil tank, the other end of the second oil suction filter is connected to the second oil suction switch, the other end of the second oil suction switch is connected to the second air drive pump, the other end of the second air drive pump is connected to the second pressure maintaining switch, the other end of the second pressure maintaining switch is connected to the second oil inlet, and a second pressure sensor is provided on the pipeline connecting the second pressure maintaining switch and the second oil inlet; The first pressure sensor is used to measure the pressure in the cavity of the first cylinder; The second pressure sensor is used to measure the pressure in the cavity of the second cylinder; The reciprocating drive system is used to drive the piston rod to perform reciprocating motion; The pressure module is used to adjust the pressure in the cavity of the first cylinder and the pressure in the cavity of the second cylinder to the first pressure, the second pressure and the external environment pressure respectively when the piston rod is not in contact with the first bushing and the second bushing; when the piston rod is in contact with the first bushing and the second bushing, the pressure in the cavity of the first cylinder is adjusted to the first pressure and the second pressure respectively, and the pressure in the cavity of the second cylinder is adjusted to the external environment pressure; wherein the first pressure is less than the second pressure; The force sensor is used to measure the first friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the first pressure when the piston rod is not in contact with the first bushing and the second bushing, measure the second friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the second pressure, and measure the third friction force generated between the piston rod and the first piston rod seal and the second piston rod seal during the in-and-out stroke under the external ambient pressure; when the piston rod is in contact with the first bushing and the second bushing, measure the fourth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the out-stroke under the first pressure, and measure the fifth friction force between the piston rod and the first piston rod seal, the second piston rod seal and the seal to be tested during the in-stroke under the second pressure.

2. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes as claimed in claim 1, characterized in that: The pressure module further includes: an air source, an air circuit switch, a triplet, a first pressure reducing valve, a second pressure reducing valve, a third pressure sensor and a fourth pressure sensor; The triple piece is composed of an air filter, a pressure reducing valve and an oil mist collector connected in sequence; One end of the air circuit switch is connected to the air source; the other end of the air circuit switch is connected to the triplex; the other end of the triplex is connected to the first air drive pump via a first pressure reducing valve, and is connected to the second air drive pump via a second pressure reducing valve; a third pressure sensor is provided on the pipeline connecting the first pressure reducing valve and the first air drive pump; a fourth pressure sensor is provided on the pipeline connecting the second pressure reducing valve and the second air drive pump.

3. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit stroke as claimed in claim 1, characterized in that: Also includes: Thin-film pressure sensors, watertight connectors, and contact pressure measurement units; The thin film pressure sensor is arranged on the contact surface between the seal to be tested and the second bushing; the thin film pressure sensor is connected to the contact pressure measuring unit via a watertight connector; The thin film pressure sensor is used to measure the third pressure generated by the seal to be tested and the second bushing being squeezed by the piston rod when the piston rod contacts the first bushing and the second bushing; The watertight connector is used to transmit the received third pressure to the contact force measuring unit; The contact pressure measuring unit is used to generate the contact pressure between the seal to be tested and the piston rod after amplifying, filtering and modulating the third pressure.

4. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes as claimed in claim 1, characterized in that: The test cylinder also includes: a dust ring and a guide ring; The first end cover and the second end cover are both provided with through holes; the piston rod passes through the first end cover and the second end cover; The first end cover is connected to one end of the first cylinder body; the second end cover is connected to one end of the second cylinder body; The dust ring and the guide ring are respectively arranged on the contact surface between the first end cover and the piston rod, and the contact surface between the second end cover and the piston rod; The dust ring is used to prevent contaminants that fall on the piston rod from entering the oil when the piston rod is retracted; The guide ring is used to maintain uniform clearances between the piston rod and the first end cover and the second end cover.

5. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit stroke as claimed in claim 1, characterized in that: Also includes: Flange; The flange is used to connect the force sensor with the reciprocating drive system and the force sensor with the piston rod.

6. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes as claimed in claim 1, characterized in that: The piston rod is a stepped shaft type piston rod.

7. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes as claimed in claim 1, characterized in that: The first piston rod seal and the second piston rod seal are symmetrical seal structures.

8. A test device capable of measuring the friction force and contact pressure of a seal during its entry and exit strokes as claimed in claim 1, characterized in that: The reciprocating drive system comprises: an electric cylinder and an electric cylinder support platform; The electric cylinder is installed on the electric cylinder supporting platform.

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