Pressure compensation system and method for solid volume expansion measuring instrument

Abstract

The invention relates to a pressure compensation system and method for a solid volume expansion measuring instrument. A compensation rod penetrates through the side wall of any side of a shell and is in sliding connection with the side wall of any side of the shell; the piston and the closed end of the measuring tube form a sealed cavity; a static seal I and a static seal II are arranged on the sealing combination face of the sealing cover and the shell from inside to outside, a groove is formed in the end where the sealing combination face of the sealing cover and / or the shell is located, the groove is located between the static seal I and the static seal II, the groove, the static seal I and the static seal II form a closed gas collecting groove, and the gas collecting groove is communicated with the sealing cavity. Gas leaked from the static seal I in the sealed cavity flows into the sealed cavity through a gas collecting groove to enable the piston to move; the control module is used for receiving the piston displacement data and the air pressure in the closed cavity in real time and obtaining the real-time moving distance of the compensation rod needing to be controlled through calculation, so that the air pressure in the closed cavity is constant. Gas leakage of the closed cavity is effectively controlled, and meanwhile pressure compensation can be quantitatively conducted on the closed cavity according to the pressure intensity of leaked gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid volume expansion measuring instrument, in particular to a pressure compensation system and method for solid volume expansion measuring instrument. BACKGROUND

[0002] In the field of precise measurement of solid material volume expansion characteristics, the core measurement accuracy of the solid volume expansion measuring instrument directly depends on the stability of the internal pressure of the test chamber. The test chamber needs to maintain a constant pressure environment for a long time, so that the volume expansion of the solid material can be accurately inferred from the change of the internal pressure of the chamber; if the pressure fluctuates due to non-expansion factors (such as sealing leakage), it will directly lead to deviation of the measurement results, especially in the micron-level high-precision expansion measurement scene, the problem has a more significant impact on the measurement accuracy.

[0003] The test chamber sealing system of the existing solid volume expansion measuring instrument mainly relies on a single set of dynamic sealing between the stretching rod (used to stretch the measured solid) and the chamber wall, and a single set of static sealing between the chamber cover and the chamber body to achieve gas blocking. Among them, the static sealing has good initial sealing performance, but after long-term use, it is easy to cause slight gas leakage due to aging of the sealing element and shift of the assembly gap caused by temperature change; and the dynamic sealing needs to cooperate with the frequent stretching and stretching actions of the stretching rod, and the continuous friction of the sealing surface will accelerate the wear of the sealing element, and the leakage risk is much higher than that of the static sealing, and the leakage amount will gradually increase with the use time.

[0004] The inherent defects of the above-mentioned single sealing structure cause the total amount of gas in the test chamber to continuously decrease, and the pressure gradually decreases, which destroys the constant pressure environment, and if there is no effective leakage control and pressure compensation means, it will seriously restrict the measurement accuracy and long-term stability of the instrument. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a pressure compensation system and method for solid volume expansion measuring instrument, which can effectively control the gas leakage of the closed chamber and quantitatively compensate the pressure of the closed chamber according to the leakage gas pressure.

[0006] The application provides the following technical scheme: a pressure compensation system for a solid volume expansion measuring instrument, the solid volume expansion measuring instrument comprising a shell, a cover and a stretching rod, the cover and the shell jointly form a closed chamber, the stretching rod is slidably connected with the side wall of the shell through the two sides of the shell, the pressure compensation system comprises a compensation rod, a measuring tube, a distance measuring sensor, a pressure sensor and a control module; the compensation rod is slidably connected with the side wall of the shell through any side of the shell; the measuring tube is open at one end, a piston is slidably connected in the measuring tube, and the piston and the closed end of the measuring tube form a sealed cavity; the sealing joint surface of the cover and the shell is provided with static seal I and static seal II from inside to outside, the end of the sealing joint surface of the cover and / or the shell is provided with a groove, the groove is located between the static seal I and the static seal II and forms a closed gas collection groove with the static seal I and the static seal II, the gas collection groove is in communication with the sealed cavity, and the gas leaked from the static seal I of the closed chamber flows into the sealed cavity through the gas collection groove to move the piston; the distance measuring sensor is used for measuring the displacement of the piston, the pressure sensor is used for measuring the air pressure in the closed chamber, and the control module is used for receiving the piston displacement data and the air pressure in the closed chamber in real time, and the distance that the compensation rod needs to move is obtained through calculation, and the compensation rod is controlled to move in real time, so that the volume change amount of the compensation rod in the closed chamber is the same as the volume of the gas leaked from the closed chamber.

[0007] Further, the pressure compensation system further comprises a gland; the gland is arranged at the connection between the stretching rod and any side or both sides of the shell, the gland and the corresponding outer side wall of the shell jointly form a closed gas collection cavity, and the gas collection cavity is in communication with the sealed cavity of the measuring tube; the end of the stretching rod penetrating through the side wall of the shell penetrates through the gland, and the stretching rod is slidably connected with the gland; the connection between the stretching rod and the side wall of the shell and the connection between the stretching rod and the gland are respectively provided with dynamic seal I and dynamic seal II; the gas leaked from the automatic seal I of the closed chamber flows into the sealed cavity through the gas collection cavity to move the piston.

[0008] Further, the stretching rod is sleeved with a stretching rod sleeve, the stretching rod can slide in the stretching rod sleeve, the stretching rod sleeve is arranged between the dynamic seal I and the dynamic seal II, the two ends of the stretching rod sleeve respectively abut against the dynamic seal I and the dynamic seal II, and the stretching rod sleeve is provided with a radial air hole.

[0009] Further, the connection between the gland and the shell is provided with static seal III.

[0010] Further, the compensation rod is arranged at any side wall of the shell provided with the gland; the end of the compensation rod penetrating through the shell penetrates through the gland, and the compensation rod is slidably connected with the gland; the connection between the compensation rod and the shell and the connection between the compensation rod and the gland are respectively provided with dynamic seal III and dynamic seal IX; the gas leaked from the automatic seal III of the closed chamber flows into the sealed cavity through the gas collection cavity to move the piston.

[0011] Further, the compensation rod is sleeved with a compensation rod sleeve I, the compensation rod can slide in the compensation rod sleeve I, the compensation rod sleeve I is arranged between the dynamic seal III and the dynamic seal IX, the two ends of the compensation rod sleeve I abut against the dynamic seal III and the dynamic seal IX respectively, and the compensation rod sleeve I is provided with a radial air hole.

[0012] Further, the pressure compensation system further comprises a side cover, the side cover is arranged at the connecting position of the compensation rod and the shell, the side cover and the outer wall of the shell are combined to form a closed gas collection chamber, the gas collection chamber is communicated with the sealed cavity of the measuring pipe, the end of the compensation rod penetrating out of the shell penetrates through the side cover, and the compensation rod is slidingly connected with the side cover, the connecting position of the compensation rod and the shell and the connecting position of the compensation rod and the side cover are respectively provided with a dynamic seal X and a dynamic seal XI, and the leaked gas of the automatic seal X of the closed cavity chamber flows into the sealed cavity through the gas collection chamber, so that the piston moves.

[0013] Further, the compensation rod is sleeved with a compensation rod sleeve II, the compensation rod can slide in the compensation rod sleeve II, the compensation rod sleeve II is arranged between the dynamic seal X and the dynamic seal XI, the two ends of the compensation rod sleeve II abut against the dynamic seal X and the dynamic seal XI respectively, and the compensation rod sleeve II is provided with a radial air hole.

[0014] Further, the connecting position of the side cover and the shell is provided with a static seal IX.

[0015] A pressure compensation method for a solid volume expansion measuring instrument, based on the above pressure compensation system, comprising: the leaked gas of the closed cavity chamber from the static seal I flows into the measuring pipe through the gas collection groove, the leaked gas of the closed cavity chamber from the automatic seal I and the dynamic seal III flows into the measuring pipe through the gas collection cavity, so that the gas pressure in the sealed cavity of the measuring pipe is greater than the atmospheric pressure, thereby driving the piston to move; the displacement sensor measures the displacement of the piston in real time, and transmits the piston displacement data to the control module; the pressure sensor measures the gas pressure in the closed cavity chamber in real time, and transmits the gas pressure data in the closed cavity chamber to the control module, the control module receives the piston displacement data and the gas pressure data in the closed cavity chamber, and calculates the distance that the compensation rod needs to move according to the following formula:

[0016] Wherein, L1 is the distance that the compensation rod needs to move, L2 is the displacement of the piston, p1 is the gas pressure in the closed cavity chamber, p2 is the atmospheric pressure, S2 is the cross-sectional area of the measuring pipe, and S1 is the cross-sectional area of the compensation rod; The control module controls the length of the part of the compensation rod extending into the closed cavity chamber to increase L1 in real time, so that the volume change of the part of the compensation rod in the closed cavity chamber is the same as the volume of the leaked gas of the closed cavity chamber.

[0017] Compared with the prior art, the beneficial effects of the present application are: 1、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0018] 2、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0019] 3、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0020] 4、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0021] 5、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0022] 6、The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0024] Figure 2 The present application is provided with static seal I and static seal II on the sealing joint surface of the cover and the shell, which can effectively control the gas leakage of the closed chamber, and the recess forms a closed gas collection groove, which is communicated with the measuring tube sealed cavity, and the displacement of the measuring piston can be used to quantitatively obtain the gas leaked from the closed chamber, and the displacement of the compensation rod required to be inserted into the closed chamber is calculated to compensate the volume vacancy caused by the leakage gas, so as to real-time offset the pressure drop caused by the leakage, ensure that the pressure of the closed chamber is always maintained at a constant value, and ensure the stability of the measurement environment.

[0025] Figure 3 This is a schematic diagram of the method flow of the present invention.

[0026] Among them: 1-servo electric cylinder, 2-compensation rod, 3-upper pressure cover, 4-compensation rod sleeve I, 5-housing, 6-tension rod, 7-lower pressure cover, 8-sealing cover, 9-distance sensor, 10-measuring tube, 11-piston, 12-hose, 13-static seal I, 14-upper air collection chamber, 15-air collection groove, 16-lower air collection chamber, 17-pressure sensor, 18-static seal II, 19-static seal III, 20-dynamic seal I, 21-dynamic seal II, 22-dynamic seal III, 23-dynamic seal IX. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] The solid volume expansion measuring instrument includes a housing 5, a cover 8, and a tension rod 6. The cover 8 and the housing 5 together form a closed chamber. The contact surface between the cover 8 and the housing 5 is the sealing surface of the cover 8, and the contact surface between the housing 5 and the cover 8 is the sealing surface of the housing 5. The closed chamber serves as the measuring chamber, containing the solid to be measured. The tension rod 6 passes through both sides of the housing 5 and is slidably connected to the side walls of the housing 5. The portion of the tension rod 6 located inside the measuring chamber is connected to the solid to be measured. The tension rod 6 slides relative to the side walls of the housing 5 to stretch the solid to be measured. Whether the air pressure inside the measuring chamber remains constant during the measurement process affects the accuracy of the solid volume expansion measurement.

[0029] Example 1 This invention provides a pressure compensation system for a solid volume expansion measuring instrument, such as... Figure 1 As shown, the pressure compensation system includes static seal I 13, static seal II 18, compensation rod 2, measuring tube 10, distance sensor 9, pressure sensor 17, and control module.

[0030] The compensating rod 2 passes through and slidably connects to any side wall of the housing 5; as the compensating rod 2 slides relative to the side wall of the housing 5, the volume occupied by the portion of the compensating rod 2 extending into the closed chamber changes accordingly, causing a change in the air pressure inside the closed chamber. In this embodiment, the compensating rod 2 is a solid columnar structure with a constant cross-section.

[0031] One end of the measuring tube 10 is open, and a piston 11 is slidably connected inside it. The piston 11 and the closed end of the measuring tube 10 form a sealed cavity. In this embodiment, the measuring tube 10 is a glass circular tube with a constant cross-section. A piston 11 that can move along its axial direction is provided inside the glass circular tube. The piston 11 can be a rubber piston.

[0032] The sealing joint surface of the cover 8 and the shell 5 is provided with static seal I 13 and static seal II 18 from inside to outside, and the end of the sealing joint surface of the cover 8 and / or the shell 5 is provided with a groove, that is, the end of the sealing joint surface of the cover 8 is provided with a groove, or the end of the sealing joint surface of the shell 5 is provided with a groove, or the end of the sealing joint surface of the cover 8 and the end of the sealing joint surface of the shell 5 are both provided with grooves.

[0033] The groove is located between the static seal I 13 and the static seal II 18 and forms a closed gas collection groove 15 with the static seal I 13 and the static seal II 18, the gas collection groove 15 is in communication with the sealed cavity of the measuring tube 10, and the gas leaked from the closed cavity flows into the sealed cavity through the gas collection groove 15 to make the piston 11 move.

[0034] In the embodiment, the end of the sealing joint surface of the cover 8 is provided with a groove, and the outer side wall on one side of the cover 8 is provided with a vent hole for the gas collection groove 15 to communicate with the measuring tube 10 through the hose 12. In the initial state, the internal gas pressure of the gas collection groove 15 is consistent with the atmospheric pressure, that is, the gas pressure in the sealed cavity of the measuring tube 10 is consistent with the atmospheric pressure, and the piston 11 is in a static state. During the measurement of the solid volume dilatometer, the gas leaked from the static seal I 13 of the closed cavity is collected in the gas collection groove 15 and enters the sealed cavity of the measuring tube 10 through the hose 12, the gas pressure in the sealed cavity increases, and the piston 11 moves to the open end of the measuring tube 10.

[0035] The distance measuring sensor 9 is used to measure the displacement of the piston 11, and in the embodiment, the distance measuring sensor 9 is a laser distance measuring sensor. The pressure sensor 17 is used to measure the gas pressure in the closed cavity. The control module is used to receive the displacement data of the piston 11 and the gas pressure in the closed cavity in real time, and the distance that the compensation rod 2 needs to move is obtained through calculation, and the control module can control the compensation rod 2 to move in real time, so that the volume change of the compensation rod 2 in the closed cavity is the same as the volume of the gas leaked from the closed cavity.

[0036] In the embodiment, the control module drives the compensation rod 2 to move through the servo cylinder 1.

[0037] As an improvement, the pressure compensation system further comprises a gland, a dynamic seal I 20 and a dynamic seal II 21. The gland is arranged at the connection between the stretching rod 6 and the shell 5 on one side or both sides, and the gland and the corresponding outer side wall of the shell 5 form a closed gas collection cavity, and the gas collection cavity is in communication with the sealed cavity of the measuring tube 10.

[0038] The end of the stretching rod 6 penetrating through the side wall of the shell 5 penetrates through the gland, and the stretching rod 6 and the gland are in sliding connection; the connection between the stretching rod 6 and the side wall of the shell 5 and the connection between the stretching rod 6 and the gland are respectively provided with the dynamic seal I 20 and the dynamic seal II 21; the gas leaked from the dynamic seal I 20 of the closed cavity flows into the sealed cavity of the measuring tube 10 through the gas collection cavity to make the piston 11 move.

[0039] In the embodiment, the stretch rod 6 is provided with a gland at the connection with the side wall of the shell 5, and the two glands are respectively the upper gland 3 and the lower gland 7, and the two correspondingly formed gas collection cavities are respectively the upper gas collection cavity 14 and the lower gas collection cavity 16. The upper gland 3 and the lower gland 7 are respectively provided with a through hole penetrating through the side wall thereof, and the through hole is communicated with the sealed cavity of the measuring tube 10 through the hose 12, so that the leaked gas of the closed chamber automatic seal 120 can enter the sealed cavity of the measuring tube 10 through the upper gas collection cavity 14 and the lower gas collection cavity 16.

[0040] In the initial state, the gas pressure in the upper gas collection cavity 14, the lower gas collection cavity 16 and the gas collection groove 15 is consistent with the atmospheric pressure, and the piston 11 is in a static state; during the measurement process of the solid volume dilatometer, the leaked gas of the closed chamber automatic seal 120 is collected in the upper gas collection cavity 14 and the lower gas collection cavity 16, and enters the sealed cavity of the measuring tube 10 through the hose 12, and the gas pressure in the sealed cavity is increased, and the piston 11 moves to the open end of the measuring tube 10.

[0041] As an improvement, the stretch rod 6 is sleeved with a stretch rod sleeve, the stretch rod 6 can slide in the stretch rod sleeve, the stretch rod sleeve is arranged between the dynamic seal 120 and the dynamic seal 221, and the two ends of the stretch rod sleeve are respectively abutted with the dynamic seal 120 and the dynamic seal 221, which is equivalent to that the stretch rod sleeve is clamped between the dynamic seal 120 and the dynamic seal 221; in addition, the stretch rod sleeve is also provided with a radial air hole. When the stretch rod 6 slides relative to the shell 5, the stretch rod sleeve is used to prevent the dynamic seal 120 and the dynamic seal 221 from moving in the axial direction of the stretch rod 6; the air hole ensures that the leaked gas of the closed chamber automatic seal 120 can enter the gas collection cavity through the stretch rod sleeve.

[0042] As a further improvement, the connection between the gland and the shell 5 is provided with a static seal 119, which ensures the airtightness of the gas collection cavity, avoids the leakage of gas from the connection between the gas collection cavity and the shell 5, and ensures the accuracy of measurement.

[0043] As a further improvement, the pressure compensation system further comprises a dynamic seal 122 and a dynamic seal 123, the compensation rod 2 is arranged on the side wall of the shell 5 provided with the gland, and the compensation rod 2 penetrates the gland located on the side wall. That is, the end of the compensation rod 2 penetrating out of the shell 5 penetrates the gland, and the compensation rod 2 is in sliding connection with the gland; the connection between the compensation rod 2 and the shell 5 and the connection between the compensation rod 2 and the gland are respectively provided with the dynamic seal 122 and the dynamic seal 123; the leaked gas of the closed chamber automatic seal 122 flows into the sealed cavity of the measuring tube 10 through the gas collection cavity, so that the piston 11 moves.

[0044] In the embodiment, the compensation rod 2 is arranged on the side wall of the shell 5 provided with the upper gland 3, and the end of the compensation rod 2 penetrating out of the shell 5 penetrates the upper gland 3, that is, the upper gas collection cavity 14 can not only collect the leaked gas of the closed chamber automatic seal 120, but also collect the leaked gas of the closed chamber automatic seal 122.

[0045] In line with the mechanism of the stretching rod sleeve, the compensation rod 2 is sleeved with a compensation rod sleeve I 4, the compensation rod 2 can slide in the compensation rod sleeve I 4, the compensation rod sleeve I 4 is arranged between the dynamic seal III 22 and the dynamic seal IX 23, the two ends of the compensation rod sleeve I 4 abut against the dynamic seal III 22 and the dynamic seal IX 23 respectively, and the compensation rod sleeve I 4 is provided with a radial air hole.

[0046] In this embodiment, the static seal I 13, the static seal II 18 and the groove therebetween form a closed independent cavity (gas collection groove 15), the gland and the corresponding outer side wall of the shell 5 form a closed independent cavity (gas collection cavity), and the double-closed independent cavity structure can accurately collect the leaked gas from the static seal I 13, the dynamic seal I 20 and the dynamic seal III 22, so as to avoid that the leaked gas in the closed chamber directly diffuses to the environment; then the leaked gas collected in the closed chamber is uniformly collected into the transparent glass tube through the hose 12, a rubber piston is arranged in the glass tube, the rubber piston and the glass tube are lubricated by low-viscosity lubricating oil, when the gas in the glass tube increases, the rubber piston is pushed to move, the displacement of the rubber piston is measured by the laser measuring instrument, and the volume of the leaked gas can be accurately calculated.

[0047] After the quantitative volume of the leaked gas is obtained, the compensation rod 2 is driven by the servo electric cylinder to realize the displacement adjustment with micron-level precision, based on the calculated volume of the leaked gas, the displacement amount of the compensation rod 2 required to extend into the test chamber (the volume vacancy caused by the compensation rod 2 occupying the internal volume of the test chamber and compensating the leaked gas) can be reversely calculated, so as to real-time offset the pressure drop caused by the leakage, and ensure that the pressure in the test chamber is always maintained at a set constant value.

[0048] In this embodiment, the double-closed independent cavity structure is used to realize accurate collection and measurement of the leaked gas, and the compensation rod 2 driven by the servo electric cylinder is used for compression compensation, so that the problems of difficult prevention and control of sealing leakage and unstable pressure in the prior art are fundamentally solved, and key technical support is provided for high-precision and long-term stable measurement of solid volume expansion.

[0049] Embodiment 2 In this embodiment, the compensation rod 2 does not collect the leaked gas through the gas collection cavity formed by the gland, but through a separate compensation rod 2 gas collection chamber provided on the side cover, in this case, the compensation rod 2 can be arranged on any one side wall of the shell 5, and the specific arrangement is as follows: The side cover is arranged at the connection between the compensation rod 2 and the shell 5, the side cover and the outer side wall of the shell 5 are combined to form a closed gas collection chamber, the gas collection chamber is communicated with the sealed cavity of the measuring pipe 10, the end of the compensation rod 2 penetrating out of the shell 5 penetrates through the side cover, and the compensation rod 2 is slidingly connected with the side cover, the connection between the compensation rod 2 and the shell 5 and the connection between the compensation rod 2 and the side cover are respectively provided with dynamic seals X and XI, and the leaked gas in the closed chamber is automatically sealed by the dynamic seal X and flows into the measuring pipe 10 through the gas collection chamber, so that the piston 11 moves. In the initial state, the gas pressure in the gas collection chamber is consistent with the atmospheric pressure, and the working principle of the gas collection chamber is consistent with the working principle of the gas collection cavity, which will not be repeated here.

[0050] In the embodiment, the compensation rod 2 can also be sleeved with a compensation rod sleeve II, the compensation rod 2 can slide in the compensation rod sleeve II, the compensation rod sleeve II is arranged between the dynamic seal X and the dynamic seal XI, the two ends of the compensation rod sleeve II are respectively abutted with the dynamic seal X and the dynamic seal XI, and the compensation rod sleeve II is provided with a radial air hole.

[0051] The connection between the side cover and the shell 5 can be provided with the static seal IX, and the working mechanism of the static seal IX is consistent with the connection between the gland and the shell 5.

[0052] As shown in Figure 2 The static seal I 13, the static seal II 18, the static seal III 19, the static seal IX, the dynamic seal I 20, the dynamic seal II 21, the dynamic seal III 22, the dynamic seal IX 23, the dynamic seal X and the dynamic seal XI can all select appropriate sealing structures according to actual conditions, for example, all can adopt sealing rings.

[0053] Embodiment 3 The application provides a pressure compensation method for a solid volume expansion measuring instrument, which is based on the above pressure compensation system, and the pressure compensation method comprises the following steps: The leaked gas in the closed chamber from the static seal I 13 flows into the measuring pipe 10 through the gas collection groove 15, and the leaked gas in the closed chamber from the dynamic seal I 20 and the dynamic seal III 22 flows into the measuring pipe 10 through the gas collection cavity (see Embodiment 1); or the leaked gas in the closed chamber from the static seal I 13 flows into the measuring pipe 10 through the gas collection groove 15, the leaked gas in the closed chamber from the dynamic seal I 20 flows into the measuring pipe 10 through the gas collection cavity, and the leaked gas in the closed chamber from the dynamic seal X flows into the measuring pipe 10 through the gas collection chamber (see Embodiment 2), so that the gas pressure in the sealed cavity of the measuring pipe 10 is greater than the atmospheric pressure, thereby driving the piston 11 to move towards the open end of the measuring pipe 10.

[0054] The displacement sensor 9 measures the displacement of the piston 11 in real time and transmits the piston 11 displacement data to the control module; the pressure sensor 17 measures the gas pressure in the closed chamber in real time and transmits the gas pressure data in the closed chamber to the control module, and the control module receives the piston 11 displacement data and the gas pressure data in the closed chamber.

[0055] According to the ideal gas state equation pV=nRT, wherein p is the gas pressure, V is the gas volume, n is the amount of substance of the gas, R is the ideal gas constant, and T is the thermodynamic temperature, it can be known that , wherein p1 is the gas pressure in the closed chamber, p2 is the atmospheric pressure, V1 is the volume change amount of the closed chamber part in which the compensation rod 2 is located, and V2 is the volume of the leaked gas in the closed chamber under the atmospheric pressure p2. The compensation rod 2 and the measuring pipe 10 are both columnar structures with constant cross sections, the volume change amount V1 of the closed chamber part in which the compensation rod 2 is located is , and the volume of the leaked gas in the closed chamber is . The formula (1) can be derived to calculate the distance L1 that the compensation rod 2 needs to move: (1) , wherein L1 is the distance that the compensation rod 2 needs to move, L2 is the displacement of the piston 11, S2 is the cross-sectional area of the measuring pipe 10, and S1 is the cross-sectional area of the compensation rod 2.

[0056] In the specific implementation, the cross sections of the compensation rod 2 and the measuring pipe 10 are both circular, and the distance that the compensation rod 2 needs to move can be calculated through the formula (2): (2) , wherein D is the inner diameter of the measuring pipe 10, and d is the diameter of the compensation rod 2.

[0057] The control module controls the compensation rod 2 to increase L1 in the part of the closed chamber into which the compensation rod 2 extends, so that the volume change amount of the closed chamber part in which the compensation rod 2 is located is the same as the volume of the leaked gas in the closed chamber.

[0058] The overall process is shown in Figure 3 , the control module can collect the displacement L2 of the piston 11 and the gas pressure p1 in the closed chamber in real time, according to the input atmospheric pressure p2, the inner diameter D of the glass pipe and the diameter d of the compensation rod 2, the control module calculates the extension distance L1 of the compensation rod 2 through the built-in formula (2), and controls the servo cylinder 1 to move so that the compensation rod 2 extends into the closed chamber by L2, to ensure that the gas pressure in the closed chamber remains unchanged.

[0059] The present application constructs a set of integrated technical solutions of “precise collection of leakage-quantitative measurement-active compensation”, realizes precise collection of leakage gas through a double-closed independent cavity structure, accurately measures the leakage amount of gas through the glass pipe piston 11, and converts the extension displacement of the compensation rod 2 according to the ideal gas state equation, to combine the compensation rod 2 compressed by the servo electric cylinder drive, to fundamentally solve the problems of difficult prevention and control of sealing leakage and low pressure compensation accuracy in the prior art, and to provide key technical support for high-precision and long-term stable measurement of solid volume expansion.

[0060] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims with respect to the figures of the patent document.

Claims

1. A pressure compensation system for a solid volume expansion measuring instrument, the solid volume expansion measuring instrument comprising a housing, a cover, and a tension rod, the cover and housing forming a closed chamber, the tension rod passing through both sides of the housing and slidably connected to the side wall of the housing, characterized in that: The pressure compensation system includes a compensation rod, a measuring tube, a distance sensor, a pressure sensor, and a control module. The compensating rod passes through and is slidably connected to either side wall of the housing. One end of the measuring tube is open, and a piston is slidably connected inside it. The piston and the closed end of the measuring tube form a sealed cavity. The sealing surfaces of the cover and the shell are provided with static seal I and static seal II from the inside to the outside. The end of the sealing surface of the cover and / or the shell is provided with a groove. The groove is located between static seal I and static seal II and forms a closed gas collection groove with the two. The gas collection groove is connected to the sealing cavity. The gas leaking from static seal I into the sealed cavity flows into the sealing cavity through the gas collection groove, causing the piston to move. The distance sensor is used to measure the piston displacement, and the pressure sensor is used to measure the air pressure in the closed chamber. The control module is used to receive piston displacement data and air pressure in the closed chamber in real time, calculate the distance that the compensation rod needs to move, and control the compensation rod to move in real time so that the volume change of the part of the compensation rod in the closed chamber is the same as the volume of gas leaking from the closed chamber.

2. The pressure compensation system for a solid volume expansion measuring instrument according to claim 1, characterized in that: The pressure compensation system also includes a pressure cap; The pressure cap is set at the connection between the tension rod and any one or both sides of the housing. The pressure cap and the corresponding outer wall of the housing form a closed gas collection cavity, which is connected to the sealing cavity of the measuring tube. The end of the tension rod that protrudes from the side wall of the housing passes through the pressure cap, and the tension rod is slidably connected to the pressure cap; dynamic seal I and dynamic seal II are respectively provided at the connection between the tension rod and the side wall of the housing and at the connection between the tension rod and the pressure cap; gas leaking from the automatic seal I of the closed chamber flows into the sealing chamber through the gas collection chamber, causing the piston to move.

3. The pressure compensation system for a solid volume expansion measuring instrument according to claim 2, characterized in that: The tension rod assembly includes a tension rod sleeve, within which the tension rod can slide. The tension rod sleeve is positioned between dynamic seal I and dynamic seal II, with both ends of the tension rod sleeve abutting against dynamic seal I and dynamic seal II respectively. The tension rod sleeve is also provided with radial vent holes.

4. The pressure compensation system for a solid volume expansion measuring instrument according to claim 2, characterized in that: A static seal III is provided at the connection between the gland and the housing.

5. The pressure compensation system for a solid volume expansion measuring instrument according to any one of claims 2-4, characterized in that: The compensating rod is installed on any side wall of the housing with a pressure cap; The end of the compensating rod that protrudes from the housing passes through the pressure cover, and the compensating rod and the pressure cover are slidably connected; dynamic seal III and dynamic seal IX are respectively provided at the connection between the compensating rod and the housing and at the connection between the compensating rod and the pressure cover; gas leaking from the automatic seal III of the closed chamber flows into the sealing chamber through the gas collection chamber, causing the piston to move.

6. The pressure compensation system for a solid volume expansion measuring instrument according to claim 5, characterized in that: The compensating rod sleeve is equipped with a compensating rod sleeve I, and the compensating rod can slide inside the compensating rod sleeve I. The compensating rod sleeve I is disposed between dynamic seal III and dynamic seal IX. Both ends of the compensating rod sleeve I abut against dynamic seal III and dynamic seal IX respectively, and the compensating rod sleeve I is provided with radial vent holes.

7. The pressure compensation system for a solid volume expansion measuring instrument according to any one of claims 1-4, characterized in that: The pressure compensation system also includes a side cover; The side cover is located at the connection between the compensation rod and the housing. The side cover and the outer wall of the housing together form a closed gas collection chamber, which is connected to the sealing cavity of the measuring tube. The end of the compensating rod that protrudes from the housing passes through the side cover, and the compensating rod is slidably connected to the side cover; dynamic seal X and dynamic seal XI are respectively provided at the connection between the compensating rod and the housing and the connection between the compensating rod and the side cover; the gas leaked from the closed chamber through the gas collection chamber flows into the sealing chamber, causing the piston to move.

8. The pressure compensation system for a solid volume expansion measuring instrument according to claim 7, characterized in that: The compensating rod is fitted with a compensating rod sleeve II, and the compensating rod can slide inside the compensating rod sleeve II. The compensating rod sleeve II is located between the dynamic seal X and the dynamic seal XI. Both ends of the compensating rod sleeve II abut against the dynamic seal X and the dynamic seal XI respectively, and the compensating rod sleeve II is provided with radial vent holes.

9. The pressure compensation system for a solid volume expansion measuring instrument according to claim 7, characterized in that: A static seal IX is provided at the connection between the side cover and the housing.

10. A pressure compensation method for a solid volume expansion measuring instrument, based on the pressure compensation system as described in claim 5 or 6, characterized in that: Gas leaking from the self-static seal I in the closed chamber flows into the measuring tube through the gas collection groove, and gas leaking from the automatic seal I and dynamic seal III in the closed chamber flows into the measuring tube through the gas collection chamber, making the gas pressure in the sealing chamber of the measuring tube greater than the atmospheric pressure, thereby pushing the piston to move. The distance sensor measures the piston displacement in real time and transmits the piston displacement data to the control module; the pressure sensor measures the air pressure inside the closed chamber in real time and transmits the air pressure data inside the closed chamber to the control module. The control module receives the piston displacement data and the air pressure data inside the closed chamber and calculates the distance that the compensation rod needs to move according to the following formula. Where L1 is the distance the compensating rod needs to move, L2 is the piston displacement, p1 is the air pressure in the closed chamber, p2 is the atmospheric pressure, S2 is the cross-sectional area of ​​the measuring tube, and S1 is the cross-sectional area of ​​the compensating rod. The control module controls the extension of the compensating rod into the closed chamber to increase by L1 in real time, so that the volume change of the part of the compensating rod in the closed chamber is the same as the volume of gas leaking from the closed chamber.

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