Piston dynamic flowmeter with integrated variable flux velocity sensor

Abstract

The application provides a piston type dynamic flowmeter integrated with a variable magnetic flux speed sensor, which is internally formed with a metering cavity, and is internally provided with a metering unit, the metering unit comprising a piston shaft arranged in an axial direction and a piston movably sleeved on the piston shaft; further comprising a speed sensor unit, which comprises a permanent magnet arranged in the metering cavity to form a magnetic field and a coil for acquiring an induced electromotive force; when the metering cavity performs liquid suction and liquid discharge, the piston reciprocally moves in an axial direction on the piston shaft, the size of the magnetic flux in the metering cavity can be changed, the coil correspondingly acquires the induced electromotive force of the magnetic field, the moving speed of the piston is acquired based on the induced electromotive force, and the flow rate can be acquired by combining the effective cross-sectional area of the piston; since the moving speed is a continuous signal, instantaneous measurement is realized; the moving speed of the piston is proportional to the output voltage of the coil, the output voltage is proportional to the flow rate signal, the linearity is high, the response frequency is high, and the precision of dynamic measurement of the flowmeter is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of flow meter technology, and in particular to a piston-type dynamic flow meter with an integrated variable flux velocity sensor. Background Technology

[0002] Flow meters are closely related to the national economy, national defense, and scientific research. In today's era of energy crisis and increasing automation in industrial production, the status and role of flow meters in the national economy are even more prominent.

[0003] Positive displacement flow meters offer high measurement accuracy and are less affected by fluid viscosity and flow state, making them widely used in aerospace, shipbuilding, mechatronics, and chemical engineering. Piston flow meters, as a type of high-precision positive displacement flow meter, can be divided into rotary piston flow meters and reciprocating piston flow meters based on the piston's movement. Reciprocating piston flow meters have a complex structure and are commonly used in refueling mechanisms at gas stations. Rotary piston flow meters have a slightly simpler structure, allowing for a certain amount of leakage to reduce wear and improve contamination resistance, but at the cost of measurement accuracy; they can be used to measure liquids such as water and liquid food products.

[0004] In existing technologies, volumetric flow meters utilize several magnets spaced at equal intervals along the circumference of a rotating component (e.g., a piston) and a Hall element on a fixed component (housing). The magnets and Hall elements interact to generate pulse signals. As the magnets rotate circumferentially, they align with the Hall element at regular intervals, causing the Hall element to emit a corresponding voltage pulse signal to mark the number of flow rates per unit volume of liquid, thus measuring the flow rate. However, the limited number of magnets results in discrete data obtained by the flow meter, leading to poor measurement accuracy.

[0005] Therefore, the above-mentioned prior art has at least the following technical problems: the flow data measured by the volumetric flow meter in the prior art is discrete and the measurement accuracy is poor. Summary of the Invention

[0006] This application provides a piston-type dynamic flow meter with an integrated variable flux velocity sensor, which solves the technical problem that the flow data measured by the existing volumetric flow meter is discrete and has poor measurement accuracy.

[0007] To solve the above technical problems, this application provides a piston-type dynamic flow meter with an integrated variable flux velocity sensor, including a cylinder body, in which a metering cavity is formed, defined as the axial direction along or parallel to the central axis of the metering cavity, and the circumferential direction around the central axis of the metering cavity.

[0008] The metering chamber is equipped with a metering unit, through which liquid is fed into and discharged. The metering unit includes a piston shaft extending along the axial direction and a piston movably sleeved on the piston shaft.

[0009] The piston divides the metering chamber into two volume chambers. The cylinder body has an inlet channel and an outlet channel at both ends. During the process of the piston reciprocating along the axial direction and rotating circumferentially in the metering chamber, the two volume chambers alternately connect the inlet channel and the outlet channel, so that the two volume chambers alternately receive and discharge liquid.

[0010] The flow meter also includes a speed sensor unit for acquiring the moving speed of the piston along the axial direction. The speed sensor unit includes permanent magnets disposed in the metering cavity and located at both ends of the piston shaft along the axial direction. The permanent magnets form a magnetic field around the piston shaft. A coil extending along the axial direction is also wound around the inner edge of the piston shaft. The coil is used to sense the electromotive force of the magnetic field.

[0011] When the metering chamber is drawing in and draining liquid, the piston reciprocates along the axial direction on the piston shaft, which can change the magnitude of the magnetic flux in the metering chamber. The coil correspondingly obtains the induced electromotive force of the magnetic field, so as to obtain the moving speed of the piston based on the induced electromotive force, thereby obtaining the flow rate according to the moving speed of the piston and the effective cross-sectional area of ​​the piston.

[0012] Furthermore, one end along the axial direction is defined as the left end and the other end as the right end, and the direction in which the diameter of the cross-section of the cylinder body is located is defined as radial.

[0013] The left end of the metering chamber is provided with a left roller support seat, and the right end of the metering chamber is provided with a right roller support seat. The left and right ends of the piston shaft are respectively fixed on the left roller support seat and the right roller support seat.

[0014] The left roller support and the piston form a left volume chamber within the cylinder body, and the right roller support and the piston form a right volume chamber within the cylinder body.

[0015] Both the left roller support and the right roller support are provided with radially extending roller shafts at the ends facing the piston. Rollers are rotatably provided at both ends of the roller shafts, and the rollers on the left roller support and the right roller support are symmetrically arranged with respect to the cross-section of the piston.

[0016] The piston has guide surfaces at its left and right ends that cooperate with the rollers. The guide surfaces are all axially annular curved surfaces with axial undulations. The projection of the guide surface in the direction of the central axis is annular. The curved surface has two highest points and two lowest points. The highest and lowest points are located on two mutually perpendicular diameters of the annulus. The curved surface is symmetrical with respect to the two diameters.

[0017] The undulating waveforms of the guide rail surfaces at both ends of the piston are staggered by 90°. When the rollers roll against the corresponding guide rail surfaces, they can synchronously drive the piston to rotate circumferentially and move axially.

[0018] Two axisymmetric left axial grooves and two axisymmetric right axial grooves are formed on the outer surface of the piston. The left axial grooves and the right axial grooves are alternately arranged at equal angles along the circumferential direction on the outer surface of the piston. The left axial grooves are connected to the left volume cavity, and the right axial grooves are connected to the right volume cavity.

[0019] The cylinder body has a left annular groove at the left end, and two axially symmetrical left axial blind holes are also provided on the wall surface of the left end of the cylinder body. A left window is opened on the left axial blind hole and runs through the radial direction. The left window is used to communicate with the left axial groove or the right axial groove.

[0020] The right end of the cylinder body is provided with a right annular groove, and the wall surface of the right end of the cylinder body is also provided with two axially symmetrical right axial blind holes. The right axial blind holes are provided with right windows that extend along the radial direction. The right windows are used to communicate with the left axial groove or the right axial groove.

[0021] The projections of the left axial blind hole and the right axial blind hole on the cross-section of the cylinder block are alternately arranged at equal angles along the circumferential direction;

[0022] The cylinder body is provided with an inlet and an outlet at its left and right ends, respectively; the inlet, the left annular groove, the left axial blind hole, and the left window are connected in sequence to form an inlet channel; the right window, the right annular groove, the right axial blind hole, and the outlet are connected in sequence to form an outlet channel.

[0023] During the reciprocating and rotating motion of the piston along the axial direction, the left volume chamber, the right volume chamber, the left axial groove, the right axial groove, the inlet channel, and the outlet channel have the following corresponding relationships:

[0024] In the first state:

[0025] The liquid being tested drives the piston to move to the right along the axial direction, and the piston rotates circumferentially under the force of the roller; the left axial groove is aligned with the left window, the right axial groove is aligned with the right window, the left volume chamber is filled with liquid through the connected left axial groove and the liquid inlet channel, and the right volume chamber is drained with liquid through the connected right axial groove and the liquid outlet channel.

[0026] Second state:

[0027] The piston moves and rotates to the left along the axial direction under the cooperation of the roller and the guide rail surface; the left axial groove is not connected to the left window or the right window, the right axial groove is not connected to the left window or the right window, the left volume chamber neither receives nor discharges liquid, and the right volume chamber neither receives nor discharges liquid;

[0028] In the third state:

[0029] The liquid being tested drives the piston to move to the left along the axial direction, and the piston rotates circumferentially under the force of the roller; the right axial groove is aligned with the left window, and the left axial groove is aligned with the right window; the left volume chamber drains liquid through the connected right axial groove and the liquid outlet channel, and the right volume chamber receives liquid through the connected left axial groove and the liquid inlet channel;

[0030] In the fourth state:

[0031] The piston moves and rotates to the right along the axial direction under the cooperation of the roller and the guide rail surface; the left axial groove is not connected to the left window or the right window, the right axial groove is not connected to the left window or the right window, the left volume chamber neither receives nor discharges liquid, and the right volume chamber neither receives nor discharges liquid.

[0032] Furthermore, the cylinder body has a left end cap at the left end and a right end cap at the right end, and the left end cap and the right end cap enclose the inner cavity of the cylinder body to form the metering cavity;

[0033] The left roller support seat is axially constrained in the cylinder by the piston and the left end cover, and the right roller support seat is axially constrained in the cylinder by the piston and the right end cover.

[0034] A left elastic seal is provided between the left roller bracket and the left end cover, and a right elastic seal is provided between the right roller bracket and the right end cover.

[0035] Furthermore, the permanent magnet includes a left permanent magnet and a right permanent magnet coaxially disposed at both ends of the piston shaft along the axial direction, wherein the magnetic pole directions of the left permanent magnet and the right permanent magnet are the same.

[0036] Furthermore, the ends of the left and right permanent magnets facing into the cylinder are both S poles, and the ends of the left and right permanent magnets facing out of the cylinder are both N poles.

[0037] Furthermore, the left roller support seat is coaxially provided with a left stepped through hole, which includes a large left drill hole at the left end and a small left drill hole at the right end.

[0038] The right roller support seat is coaxially provided with a right stepped through hole, which includes a right large drill hole at the right end and a right small drill hole at the left end.

[0039] The left end of the piston shaft is installed in the left small drill hole, and the right end of the piston shaft is installed in the right small drill hole;

[0040] The permanent magnet includes a left permanent magnet coaxially disposed at the left end of the piston shaft and a right permanent magnet coaxially disposed at the right end. The left permanent magnet is disposed in the left large borehole and the right permanent magnet is disposed in the right large borehole.

[0041] Furthermore, the right end face of the left roller bracket is provided with a left mounting groove for accommodating the corresponding roller, and the left end face of the right roller bracket is provided with a right mounting groove for accommodating the corresponding roller.

[0042] Furthermore, a first left sealing ring is provided between the left end cover and the inner wall surface of the cylinder body, and a first right sealing ring is provided between the right end cover and the inner wall surface of the cylinder body;

[0043] A second left sealing ring is provided between the left end cover and the left end face of the cylinder body, and a second right sealing ring is provided between the right end cover and the right end face of the cylinder body;

[0044] A third left sealing ring is provided between the left roller bracket and the piston shaft, and a third right sealing ring is provided between the right roller bracket and the piston shaft.

[0045] Furthermore, a stator core is coaxially disposed inside the piston shaft, and the coil is wound on the stator core.

[0046] Furthermore, the flow meter also includes a controller connected to the coil for receiving the induced electromotive force acquired by the coil, and for obtaining the moving speed of the piston based on the induced electromotive force, and further calculating the flow rate based on the moving speed and the effective cross-sectional area of ​​the piston.

[0047] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0048] (1) This embodiment of the application sets up a metering unit so that the piston can perform liquid inlet and outlet during axial reciprocating movement and circumferential rotation. This embodiment of the application also sets up a speed sensor unit, which includes a permanent magnet and a coil for inducing the electromotive force of the magnetic field. The permanent magnet forms a magnetic field around the piston shaft. When the piston moves axially on the piston shaft, the magnitude of the magnetic flux in the metering cavity can be changed. The coil correspondingly obtains the induced electromotive force of the magnetic field, so the moving speed of the piston can be obtained based on the induced electromotive force, and the flow rate can be calculated based on the moving speed and the effective cross-sectional area of ​​the piston, i.e., q=|v|·a, where: q is the flow rate, v is the moving speed, and a is the effective cross-sectional area of ​​the piston. Since the obtained moving speed is a continuous signal, instantaneous measurement is realized. Moreover, the piston moving speed is proportional to the output voltage of the coil, and the output voltage is proportional to the flow signal. It has high linearity and high response frequency, which greatly improves the accuracy of dynamic measurement of the flow meter and effectively solves the technical problem that the flow data measured by the volumetric flow meter in the prior art is discrete and the measurement accuracy is poor.

[0049] (2) Since the coil and permanent magnet are fixedly installed in the cylinder in this embodiment, the speed sensor unit will not move synchronously with the moving parts (piston) in the cylinder. At the same time, the speed sensor unit will not limit the piston's stroke. Therefore, when the piston moves, it will not interfere with the wiring inside the cylinder. Compared with the prior art, the flow meter has a smaller overall size and higher integration when it has the same stroke.

[0050] (3) In this embodiment of the application, the coil is placed inside the piston shaft, which isolates the liquid to be measured from the coil, so that the flow meter can work under higher pressure. At the same time, it can prevent the coil from being worn when the piston moves, effectively avoid interference or contamination, and thus extend the service life of the flow meter.

[0051] (4) The shape of the guide surface in the embodiment of this application makes the piston satisfy the law of equal acceleration and deceleration. That is, in each movement interval, the piston accelerates with the same acceleration in the first half of the interval and decelerates with the same deceleration in the second half of the interval, so that the piston has the same acceleration curve when moving to the left and to the right, without any sudden acceleration, so that the axial movement of the two-dimensional piston is clear and controllable.

[0052] (5) In the embodiment of this application, when the piston rotates 360°, the flow meter completes two reciprocating motions to achieve two oil intake and discharge, while the traditional piston flow meter can only perform one liquid intake and discharge. Under the premise of the same measurement range, the flow meter described in the embodiment of this application can be miniaturized and the cost can be greatly reduced.

[0053] (6) In the embodiment of this application, the piston shaft is fixedly arranged so that the piston can continuously feed and discharge liquid when rotating in the circumferential direction and moving in the axial direction. Since the piston shaft is fixed, the mass of the rotating parts of the flow meter is reduced and the dynamic frequency response of the flow meter is improved.

[0054] (7) In this embodiment of the application, the piston shaft is fixed inside the cylinder and does not need to extend out of the cylinder. Compared with the traditional piston flow meter, it can prevent liquid from leaking out of the cylinder from the gap between the piston shaft and the cylinder, thus eliminating liquid leakage.

[0055] (8) The embodiments of this application adopt a piston with a two-degree-of-freedom structure, which is simpler in structure than the traditional piston flow meter, and can realize bidirectional flow measurement, effectively expanding the application range of dynamic flow meter and realizing the multi-functional use effect of dynamic flow meter.

[0056] (9) In the embodiment of this application, the roller support seat is axially constrained in the cylinder by the piston and the end cover, and an elastic seal is provided between the roller support seat and the end cover. The elastic seal can compensate for the gap between the roller and the guide rail surface during the piston movement, thereby ensuring the accuracy of flow measurement and being able to adapt to different flow rates and flow states.

[0057] (10) The flow meter described in this application embodiment also includes a controller, which can automatically calculate the moving speed of the piston based on the output voltage corresponding to the induced electromotive force of the coil, and further calculate the flow rate based on the moving speed and the effective cross-sectional area of ​​the piston, thereby realizing automated processing and visualization display, and improving the intelligence level of the flow meter. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 This is a 90° cross-sectional view of the flow meter provided in one embodiment of this application in its first state;

[0060] Figure 2 This is a structural cross-sectional view of the flow meter provided in one embodiment of this application;

[0061] Figure 3 This is a structural cross-sectional view of the left roller support and the right roller support in one embodiment of this application;

[0062] Figure 4a This is a schematic diagram of the piston structure in one embodiment of this application;

[0063] Figure 4b This is a schematic diagram of the structure of the piston upper guide surface in one embodiment of this application;

[0064] Figure 5 This is a schematic diagram of the assembly of the roller and the left roller support or the right roller support in one embodiment of this application;

[0065] Figure 6 This is a cross-sectional view of the structure of the roller and roller shaft assembly in one embodiment of this application;

[0066] Figure 7a In one embodiment of this application, the piston and cylinder are in the first state along Figure 2 Sectional view along the middle AA direction;

[0067] Figure 7b In one embodiment of this application, the piston and cylinder are in the second state along Figure 2 Sectional view along the middle AA direction;

[0068] Figure 7c In one embodiment of this application, the piston and cylinder are in the third state along Figure 2 Sectional view along the middle AA direction;

[0069] Figure 7d In one embodiment of this application, the piston and cylinder are in the fourth state along Figure 2 Sectional view along the middle AA direction;

[0070] Figure 8 This is a schematic diagram showing the relationship between the piston movement speed and the coil output voltage of the flow meter provided in this application embodiment;

[0071] Figure 9 This is a schematic diagram of the coil output voltage when the two-dimensional piston moving speed of the flow meter provided in this application embodiment is 80 mm / s. Detailed Implementation

[0072] This application provides a piston-type dynamic flow meter with an integrated variable flux velocity sensor, which solves the technical problem that the flow data measured by the existing volumetric flow meter is discrete and has poor measurement accuracy.

[0073] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0074] By setting up a metering unit, the piston can perform liquid feeding and discharging during axial reciprocating movement and circumferential rotation.

[0075] A speed sensor unit is also provided, which includes a permanent magnet and a coil for inducing the electromotive force of the magnetic field. The permanent magnet forms a magnetic field around the piston shaft. When the piston moves axially on the piston shaft, the magnitude of the magnetic flux in the metering cavity can be changed. The coil correspondingly obtains the induced electromotive force of the magnetic field, so the moving speed of the piston can be obtained based on the induced electromotive force. The flow rate can be further calculated based on the moving speed and the effective cross-sectional area of ​​the piston, i.e., q=|v|·a, where: q is the flow rate, v is the moving speed, and a is the effective cross-sectional area of ​​the piston.

[0076] Since the acquired moving speed is a continuous signal, instantaneous measurement is achieved. Furthermore, the piston moving speed is proportional to the coil output voltage, and the output voltage is proportional to the flow signal. This results in high linearity and high response frequency, which greatly improves the accuracy of dynamic measurement of the flow meter. It effectively solves the technical problem that the flow data measured by the existing volumetric flow meter is discrete and has poor measurement accuracy.

[0077] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0078] One or more embodiments of this application provide a piston-type dynamic flow meter with an integrated variable flux velocity sensor, which is used to measure the flow rate of a liquid.

[0079] like Figure 1 , 2 As shown, the flow meter includes a cylinder 8, which is a hollow cylinder. In this embodiment, the axial direction is defined as the direction of the central axis of the cylinder 8 or a direction parallel to the central axis of the cylinder 8; axial symmetry refers to symmetry about the central axis of the cylinder 8; radial direction refers to the direction of the diameter of the cross-section of the cylinder 8; and circumferential direction refers to the direction around the central axis of the cylinder 8. One end along the axial direction is the left end, and the opposite end is the right end. The following descriptions will follow the above reference orientations and will not be repeated. However, it should be noted that the above terms of orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0080] like Figure 1 , 2 As shown, the left end of the cylinder body 8 is provided with a left end cover 1, and the right end of the cylinder body 8 is provided with a right end cover 14. The left end cover 1 and the right end cover 14 enclose the inner cavity of the cylinder body 8 to form a metering cavity. A metering unit is provided in the metering cavity, and the metering cavity is used for liquid inlet and outlet through the metering unit.

[0081] The metering unit includes a piston shaft 6 that extends fixedly along the axial direction and a piston 7 that is movably sleeved on the piston shaft 6. The piston 7 can reciprocate along the axial direction and can rotate in the circumferential direction.

[0082] The piston 7 seals and divides the metering chamber into a left volume chamber D at the left end and a right volume chamber I at the right end. The cylinder body 8 has an inlet channel and an outlet channel at both ends. During the process of the piston 7 reciprocating along the axial direction and rotating circumferentially in the metering chamber, the two volume chambers (i.e., the left volume chamber D and the right volume chamber I) alternately connect the inlet channel and the outlet channel, so that the two volume chambers alternately receive and discharge liquid.

[0083] The flow meter also includes a speed sensor unit for acquiring the axial movement speed of the piston 7. The speed sensor unit is disposed in the metering cavity and includes permanent magnets disposed at the left and right ends of the piston shaft 6. The permanent magnets form a magnetic field around the piston shaft 6. The piston shaft 6 is also provided with a coil 17 for sensing the electromotive force of the magnetic field. The coil 17 extends and winds along the axial direction.

[0084] When the metering chamber is drawing in and draining liquid, the piston 7 reciprocates along the axial direction on the piston shaft 6, which can change the magnitude of the magnetic flux in the metering chamber. The coil 17 correspondingly obtains the induced electromotive force of the magnetic field, so as to obtain the moving speed of the piston 7 based on the induced electromotive force, thereby obtaining the flow rate according to the moving speed of the piston 7 and the effective cross-sectional area of ​​the piston 7.

[0085] Specifically, in this embodiment, the effective cross-sectional area of ​​the piston 7 refers to the cross-sectional area of ​​the piston 7.

[0086] Furthermore, the permanent magnet forms a magnetic field around the piston shaft 6. When the piston 7 moves axially, the magnitude of the magnetic flux in the metering chamber 8 changes accordingly. According to the law of electromagnetic induction, a voltage proportional to the rate of change of magnetic flux through the coil 17 is generated on the coil 17. Figure 8 , 9 As shown, according to the simulation results, when the number of turns of the coil 17 remains unchanged, the moving speed of the piston 7 is directly proportional to the output voltage of the coil 17, and the two are linearly related. Moreover, the dynamic response of the output voltage of the coil 17 is fast, that is, the moving speed of the piston 7 can be accurately reflected according to the output voltage of the coil 17.

[0087] As described above, this embodiment of the application, by setting a metering unit, enables the piston 7 to perform liquid inlet and outlet during axial reciprocating movement and circumferential rotation. This embodiment also includes a speed sensor unit, which comprises a permanent magnet and a coil 17 for inducing the electromotive force of the magnetic field. The permanent magnet forms a magnetic field around the piston shaft 6. When the piston 7 moves axially along the piston shaft 6, the magnitude of the magnetic flux within the metering cavity changes. The coil 17 correspondingly acquires the induced electromotive force of the magnetic field, thereby allowing the piston 7's moving speed to be obtained based on the induced electromotive force, and further based on the movement... The flow rate is calculated using the moving speed and the effective cross-sectional area of ​​piston 7, i.e., q = |v|·a, where q is the flow rate, v is the moving speed, and a is the effective cross-sectional area of ​​piston 7. Since the acquired moving speed is a continuous signal, instantaneous measurement is achieved. Furthermore, the moving speed of piston 7 is proportional to the output voltage of coil 17, and the output voltage is proportional to the flow signal. This results in high linearity and high response frequency, greatly improving the accuracy of dynamic measurement of the flow meter. It effectively solves the technical problem that the flow data measured by the existing volumetric flow meter is discrete and has poor measurement accuracy.

[0088] In addition, since the coil 17 and the permanent magnet are fixedly installed inside the cylinder 8 in this embodiment, the speed sensor unit will not move synchronously with the moving parts (piston 7) inside the cylinder 8. At the same time, the speed sensor unit will not restrict the movement stroke of the piston 7. Therefore, when the piston 7 moves, it will not interfere with the internal wiring of the cylinder 8. Compared with the prior art, the flow meter has a smaller overall size and higher integration when it has the same movement stroke.

[0089] Furthermore, in this embodiment, the coil 17 is disposed inside the piston shaft 6, isolating the liquid to be measured from the coil 17, allowing the flow meter to operate at higher pressures, while preventing wear on the coil 17 when the piston 7 moves, effectively avoiding interference or contamination, thereby extending the service life of the flow meter.

[0090] Still as Figure 1 , 2 As shown, in one embodiment of this application, the metering unit further includes a left roller support 4 disposed at the left end of the metering cavity and a right roller support 10 disposed at the right end of the metering cavity. The left roller support 4 and the piston 7 are sealed within the cylinder 8 to form the left volume chamber D, and the right roller support 10 and the piston 7 are sealed within the cylinder 8 to form the right volume chamber I. The piston 7 is sealed with a gap between itself and the inner wall of the cylinder 8, thereby effectively reducing internal leakage.

[0091] like Figure 3As shown, the left roller support 4 is coaxially provided with a left stepped through hole, which includes a left large drill hole R at the left end and a left small drill hole Q at the right end; the right roller support 10 is coaxially provided with a right stepped through hole, which includes a right large drill hole T at the right end and a right small drill hole P at the left end.

[0092] The left end of the piston shaft 6 is installed in the left small drill hole Q, and the right end of the piston shaft 6 is installed in the right small drill hole P; the piston 7 has an axial through hole M at its central axis, through which the piston shaft 6 passes and allows the piston 7 to move axially and rotate circumferentially on the piston shaft 6.

[0093] like Figure 5 , 6 As shown, both the left roller support 4 and the right roller support 10 are provided with roller shafts 24 on the end facing the piston 7. The roller shafts extend radially, and rollers 22 and 23 are rotatably provided at both ends of the roller shafts. The rollers on the left roller support 4 and the right roller support 10 are symmetrically arranged with respect to the cross-section of the piston.

[0094] Specifically, a roller shaft 24 is provided on the right end face of the left roller support 4, and another roller shaft 24 is provided on the left end face of the right roller support 10. The rollers 22 and 23 are rotatably mounted on their respective roller shafts 24 via bearings 25. The right end face of the left roller support 4 is provided with a left mounting groove U for accommodating the corresponding rollers 22 and 23, and the left end face of the right roller support 10 is provided with a right mounting groove V for accommodating the corresponding rollers 22 and 23. In addition, the two rollers 22 on the left roller support 4 are located on both sides of the left small drill hole Q along the radial direction, and the two rollers 23 on the right roller support 10 are located on both sides of the right small drill hole P along the radial direction.

[0095] like Figure 4a , 4b As shown, the piston 7 has guide rail surfaces X and Y on its left and right end faces respectively, which cooperate with the rollers 22 and 23. The rolling surfaces of the rollers 22 and 23 protrude from the surface of the left roller support 4 or the right roller support 10, so as to maintain tight contact with the guide rail surfaces X and Y.

[0096] The guide surfaces X and Y are both axially annular curved surfaces with axial undulations. The projections of the guide surfaces X and Y in the direction of the central axis are circular. The curved surfaces have two highest points T1 and two lowest points T2. The highest point T1 and the lowest point T2 are respectively located on two mutually perpendicular diameters of the circular ring. The curved surfaces are symmetrical with respect to the two diameters.

[0097] The undulating waveforms of the guide surfaces X and Y at both ends of the piston 7 are staggered by 90°. That is, the projections of the highest point of the left guide surface X and the lowest point of the right guide surface Y on the cross-section of the piston 7 correspond, and the projections of the lowest point of the left guide surface X and the highest point of the right guide surface Y on the cross-section of the piston 7 correspond. Thus, when the rollers 22 and 23 roll against the corresponding guide surfaces X and Y, they can synchronously drive the piston 7 to rotate circumferentially and move axially.

[0098] In this embodiment, the rolling surfaces of rollers 22 and 23 are in contact with guide rail surfaces X and Y. The extension of the contact line between rollers 22 and 23 and guide rail surfaces X and Y intersects the central axis of piston 7 at a point, which minimizes the difference in linear velocity between rollers 22 and 23 and the contact lines of guide rail surfaces X and Y, thus preventing slippage during rotation.

[0099] In one embodiment of this application, as Figure 4a , 4b As shown, two axisymmetric left axial grooves E and two axisymmetric right axial grooves H are formed on the outer surface of the piston 7. The left axial grooves E and the right axial grooves H are alternately arranged at equal angles along the circumference on the outer surface of the piston 7. The left axial groove E communicates with the left volume cavity D, and the right axial groove H communicates with the right volume cavity I.

[0100] like Figure 1 , 2 As shown, the left end of the cylinder body 8 is provided with a left annular groove A, and the wall surface of the left end of the cylinder body 8 is also provided with two axisymmetric left axial blind holes C. The left axial blind holes C are provided with a radially penetrating left window F, which is used to communicate with the left axial groove E or the right axial groove H.

[0101] The right end of the cylinder body 8 is provided with a right annular groove K, and the wall surface of the right end of the cylinder body 8 is also provided with two axially symmetrical right axial blind holes J. The right axial blind holes J are provided with a right window G that runs radially through the metering cavity. The right window G is used to communicate with the left axial groove E or the right axial groove H.

[0102] The projections of the left axial blind hole C and the right axial blind hole J on the cross-section of the cylinder 8 are alternately arranged at equal angles along the circumferential direction.

[0103] The cylinder body 8 is provided with an inlet B and an outlet L at its left and right ends, respectively. The inlet B, the left annular groove A, the left axial blind hole C, and the left window F are connected in sequence to form an inlet channel; the right window G, the right annular groove K, the right axial blind hole J, and the outlet L are connected in sequence to form an outlet channel.

[0104] During the reciprocating and rotating motion of the piston 7 along the axial direction, the left volume chamber D, the right volume chamber I, the left axial groove E, the right axial groove H, the inlet channel, and the outlet channel have the following corresponding relationships:

[0105] In the first state:

[0106] The tested liquid drives the piston 7 to move to the right along the axial direction. The piston 7 rotates circumferentially under the pressure of rollers 22 and 23. The left axial groove E is aligned with the left window F, and the right axial groove H is aligned with the right window G. The left volume chamber D receives liquid through the connected left axial groove E and the inlet channel, and the right volume chamber I discharges liquid through the connected right axial groove H and the outlet channel. Figure 7a As shown;

[0107] Second state:

[0108] The piston 7 moves and rotates to the left along the axial direction under the action of the rollers 22 and 23 and the guide surfaces X and Y; the left axial groove E is not connected to the left window F or the right window G, and the right axial groove H is not connected to the left window F or the right window G; the left volume chamber D neither receives nor discharges liquid, and the right volume chamber I neither receives nor discharges liquid. Figure 7b ;

[0109] In the third state:

[0110] The tested liquid drives the piston 7 to move to the left along the axial direction, and the piston 7 rotates circumferentially under the pressure of rollers 22 and 23; the right axial groove H is aligned with the left window F, and the left axial groove E is aligned with the right window G; the left volume chamber D drains liquid through the connected right axial groove H and the liquid outlet channel, and the right volume chamber I receives liquid through the connected left axial groove E and the liquid inlet channel, as shown below. Figure 7c As shown;

[0111] In the fourth state:

[0112] The piston 7 moves to the right along the axial direction and rotates circumferentially under the cooperation of the rollers 22 and 23 with the guide surfaces X and Y; the left axial groove E is not connected to the left window F or the right window G, the right axial groove H is not connected to the left window F or the right window G, the left volume chamber D neither receives nor discharges liquid, and the right volume chamber I neither receives nor discharges liquid. Figure 7d As shown.

[0113] Specifically, the working principle of the above-mentioned metering unit is as follows:

[0114] When the piston 7 moves along the axial direction under hydraulic drive, the guide surfaces X and Y squeeze the rollers 22 and 23, causing the rollers 22 and 23 to rotate. The reaction force of the rollers on the guide surfaces X and Y forces the piston 7 to rotate synchronously in the circumferential direction. In addition, in this embodiment, since the waveforms of the undulations of the guide surfaces X and Y are opposite to each other (90° apart), and the rollers 22 and 23 at both ends are symmetrically arranged with respect to the cross-section of the piston 7, for example, when the contact point between the roller 22 on the left side of the piston 7 and the left guide surface X moves from the lowest point T2 to the highest point T1, the contact point between the roller 23 on the right side of the piston 7 and the right guide surface Y moves exactly from the highest point T1 to the lowest point T2. The rollers 22 and 23 on both sides cause the piston 7 to move axially in the same direction.

[0115] In this embodiment, as Figure 4a , 4b As shown, the area between the lowest point T2 and the highest point T1 on the guide rail surface X and Y constitutes a motion interval. The central angle of each motion interval is 90°. Within each motion interval, the piston 7 achieves one axial movement in one direction.

[0116] The shapes of the guide surfaces X and Y ensure that the piston 7 follows the law of uniform acceleration and deceleration. That is, in each motion interval, the piston 7 accelerates with the same acceleration in the first half of the interval and decelerates with the same deceleration in the second half of the interval. This makes the piston 7 have the same acceleration curve when moving to the left and to the right, without any sudden acceleration changes. The axial movement of the piston is clear and controllable.

[0117] In this embodiment, the volume of the left volume chamber D and the volume of the right volume chamber I change during the axial movement of the piston 7. When the piston 7 is in the middle of its axial stroke, the volumes of the left volume chamber D and the right volume chamber I are equal. When the left piston 7 is at the leftmost end of its axial stroke, the volume of the left volume chamber D is at its minimum (i.e., the minimum volume of the left volume chamber D), and the volume of the right volume chamber I is at its maximum (i.e., the maximum volume of the right volume chamber I). When the piston 7 is at the rightmost end of its axial stroke, the volume of the left volume chamber D is at its maximum (i.e., the maximum volume of the left volume chamber D), and the volume of the right volume chamber I is at its minimum (i.e., the minimum volume of the right volume chamber I).

[0118] In this embodiment, the highest point T1 and the lowest point T2 within each movement interval on the guide rail surfaces X and Y have a midpoint T0. For example, in one embodiment, the central angle between the highest point T1 and the midpoint T0 is 45°, and the central angle between the lowest point T2 and the midpoint T0 is also 45°.

[0119] Defined as zero position, piston 7 is in the middle of its axial stroke, left window F is aligned with left axial groove E, right window G is aligned with right axial groove H, left roller 22 is located at the midpoint T0 of left guide surface X, and right roller 23 is located at the midpoint T0 of right guide surface Y. The high-pressure liquid to be measured enters from inlet B and exits from outlet L. Therefore, the working process of the flowmeter in this embodiment within one working cycle (0~180°) is as follows:

[0120] (1) When piston 7 rotates from 0° to 45°

[0121] At 0°, piston 7 is in the middle of its axial stroke. The left volume chamber D and the right volume chamber I have the same volume. The left axial groove E is perfectly aligned with the left window F, maximizing the communication area. The right axial groove H is perfectly aligned with the right window G, maximizing the communication area. Figure 7a As shown;

[0122] The high-pressure test liquid enters the left volume chamber D sequentially through the inlet channel and the left axial groove E, and pushes the piston 7 to move to the right along the axial direction to the rightmost end of its axial stroke. During the process of the piston 7 moving to the right along the axial direction, the right end guide rail surface Y squeezes the right roller 23. The reaction force of the roller 23 forces the piston 7 to rotate. The right roller 23 moves from the middle point T0 to the lowest point T2, and the left roller 22 moves from the middle point T0 to the highest point T1.

[0123] As piston 7 rotates from 0° to 45°, the communication area between the left axial groove E and the left window F gradually decreases from its maximum at 0° to zero, and the communication area between the right axial groove H and the right window G gradually decreases from its maximum at 0° to zero. Liquid enters the left volume chamber D sequentially through the inlet channel and the left axial groove E, and the volume of the left volume chamber D gradually increases to its maximum. Under the squeezing action of piston 7, the volume of the right volume chamber I gradually decreases to its minimum, and the liquid in the right volume chamber I is discharged sequentially through the right axial groove H and the outlet channel.

[0124] (2) When piston 7 rotates from 45° to 90°

[0125] At 45°, piston 7 is at the rightmost end of its axial stroke. The communication area between the left axial groove E and either the left window F or the right window G is zero, and the communication area between the right axial groove H and either the left window F or the right window G is zero. The left volume chamber D neither receives nor discharges liquid, and the right volume chamber I neither receives nor discharges liquid. Figure 7b As shown;

[0126] At this time, under the action of inertia, the piston continues to rotate to realize the connection between the left axial groove E and the right window G, and the connection between the right axial groove H and the left window F. The high pressure liquid enters the right volume chamber I through the liquid inlet channel and the right axial groove H in sequence, and pushes the piston 7 to move to the left along the axis to the middle position of its axial stroke. The left end guide rail surface M squeezes the left end roller 22. The reaction force of the roller 22 forces the piston 7 to continue to rotate. The left roller 22 moves from the highest point T1 to the middle point T0, and the right roller 23 moves from the lowest point T2 to the middle point T0.

[0127] As the piston 7 rotates from 45° to 90°, the connecting area between the left axial groove E and the right window G gradually increases from zero at 45° to its maximum, and the connecting area between the right axial groove H and the left window F gradually increases from zero at 45° to its maximum. The liquid enters the right volume chamber I sequentially through the inlet channel and the right axial groove H, and the volume of the right chamber gradually increases. Under the squeezing action of the piston 7, the volume of the left volume chamber D gradually decreases, and the liquid in the left volume chamber D is discharged sequentially through the left axial groove E and the outlet channel.

[0128] (3) When piston 7 rotates from 90° to 135°

[0129] At 90°, piston 7 is in the middle of its axial stroke. The communication area between the left axial groove E and the right window G is at its maximum, as is the communication area between the right axial groove H and the left window F. The flow rate of liquid discharged from the left volume chamber D is at its maximum, and the flow rate of liquid entering the right volume chamber I is at its maximum. Figure 7c As shown;

[0130] High-pressure liquid enters the right volume chamber I through the inlet channel and the right axial groove H in sequence, and pushes the piston 7 to move to the left along the axial direction to the leftmost end of its axial stroke. The left end guide surface X squeezes the left end roller 22, and the reaction force of the left end roller 22 forces the piston 7 to continue rotating. The left end roller 22 moves from the middle point T0 to the lowest point T2, and the right end roller 23 moves from the middle point T0 to the highest point T1.

[0131] During the process of piston 7 rotating from 90° to 135°, the communication area between the left axial groove E and the right window G gradually decreases from its maximum at 90° to zero, and the communication area between the right axial groove H and the left window F gradually decreases from its maximum at 90° to zero.

[0132] Liquid enters the right volume chamber I sequentially through the inlet channel and the right axial groove H, and the volume of the right volume chamber I gradually increases to its maximum. The piston 7 presses the left volume chamber D to the left, and the volume of the left volume chamber D gradually decreases to its minimum. The liquid in the left volume chamber D is discharged sequentially through the right axial groove H and the outlet channel.

[0133] (4) When piston 7 rotates from 135° to 180°

[0134] At 135°, piston 7 is at the leftmost end of its axial stroke. The communication area between the left axial groove E and either the left window F or the right window G is zero, and the communication area between the right axial groove H and either the left window F or the right window G is zero. The left volume chamber D neither receives nor discharges liquid, and the right volume chamber I neither receives nor discharges liquid. Figure 7d As shown;

[0135] At this time, under the action of inertia, the piston continues to rotate to realize the connection between the left axial groove E and the left window F and the right axial groove H and the right window G. The high pressure liquid enters the left volume chamber D through the liquid inlet channel and the left axial groove E in sequence, and pushes the piston 7 to move to the right along the axial direction to the middle position of its axial stroke. The right end guide surface N squeezes the right end roller 23. The reaction force of the right end roller 23 forces the piston 7 to continue to rotate. The left roller 22 moves from the lowest point T2 to the middle point T0, and the right roller 23 moves from the highest point T1 to the middle point T0.

[0136] During the process of piston 7 rotating from 135° to 180°, the communication area between the left axial groove E and the left window F gradually increases from zero at 135° to the maximum, and the communication area between the right axial groove H and the left window F or the right window G gradually increases from zero at 135° to the maximum.

[0137] Liquid enters the left volume chamber D sequentially through the inlet channel and the left axial groove E, causing the volume of the left volume chamber D to gradually increase. The piston 7 presses the right chamber to the right, causing the volume of the right volume chamber I to gradually decrease. Liquid in the right volume chamber I is discharged sequentially through the right axial groove H and the outlet channel.

[0138] The piston 7 repeats the above cycle once every 180° rotation. After each 180° rotation, the piston 7 completes one reciprocating motion, and the liquid passing through is one unit volume. Therefore, when the piston 7 rotates 360° in one revolution, it completes two reciprocating motions and discharges two unit volumes of liquid. Thus, the instantaneous flow rate can be calculated based on the effective cross-sectional area of ​​the piston 7 (i.e., the cross-sectional area in contact with the liquid to be measured) and the moving speed of the piston 7.

[0139] As can be seen from the above description, when the piston 7 of this embodiment rotates 360°, the flow meter completes two reciprocating motions to achieve two oil suction and discharge operations, while the traditional piston 7 type flow meter can only perform one liquid inlet and one liquid outlet operation. Under the premise of the same measurement range, the present invention can achieve miniaturization and the cost can be greatly reduced.

[0140] In addition, in this embodiment, the piston shaft 6 is fixedly installed, and the piston 7 continuously feeds and discharges liquid when rotating circumferentially and moving axially. Since the piston shaft 6 is fixed, the mass of the rotating parts of the flow meter is reduced, and the dynamic frequency response of the flow meter is improved.

[0141] Furthermore, the dynamic flow meter provided by this invention has a piston shaft 6 fixed inside the cylinder body 8 and does not need to extend outside the cylinder body 8. Compared with traditional piston flow meters, this can prevent liquid from leaking from the gap between the piston shaft 6 and the cylinder body 8 to the outside of the cylinder body 8, thus eliminating external leakage of liquid.

[0142] It should also be noted that the piston 7 with a two-degree-of-freedom structure in this embodiment is simpler in structure than the traditional piston flow meter, and can realize bidirectional flow measurement, effectively expanding the application range of the dynamic flow meter and realizing the multi-functional use effect of the dynamic flow meter.

[0143] In one embodiment of this application, the left roller support seat 4 is axially constrained in the cylinder 8 by the piston 7 and the left end cover 1, and the right roller support seat 10 is axially constrained in the cylinder 8 by the piston 7 and the right end cover 14. A left elastic seal 21 is provided between the left roller support seat 4 and the left end cover 1, and a right elastic seal 11 is provided between the right roller support seat 10 and the right end cover 14.

[0144] Specifically, the left elastic seal 21 and the right elastic seal 11 can compensate for the gap between the rollers 22 and 23 and the guide surfaces X and Y during the movement of the piston 7, thereby ensuring the accuracy of flow measurement and being able to adapt to different flow rates and conditions.

[0145] For example, in one embodiment of this application, the left elastic seal 21 may be an elastic sealing ring embedded on the left end face of the left roller bracket 4, and the right elastic seal 11 may be another elastic sealing ring embedded on the right end face of the right roller bracket 10.

[0146] In one embodiment of this application, as Figure 1 , 2 As shown, a first left sealing ring 3 is provided between the left end cover 1 and the inner wall surface of the cylinder 8, and a first right sealing ring 12 is provided between the right end cover 14 and the inner wall surface of the cylinder 8; a second left sealing ring 2 is provided between the left end cover 1 and the left end face of the cylinder 8, and a second right sealing ring 13 is provided between the right end cover 14 and the right end face of the cylinder 8; a third left sealing ring 19 is provided between the left roller bracket seat 4 and the piston shaft 6, and a third right sealing ring 16 is provided between the right roller bracket seat 10 and the piston shaft 6, so as to improve the sealing performance of the metering chamber, reduce leakage, and thus improve the accuracy of the flow meter.

[0147] Furthermore, such as Figure 2 As shown, the permanent magnet includes a left permanent magnet 20 and a right permanent magnet 15 coaxially disposed at the left and right ends of the piston shaft 6, wherein the magnetic pole directions of the left permanent magnet 20 and the right permanent magnet 15 are the same.

[0148] For example, in one embodiment of this application, the ends of the left permanent magnet 20 and the right permanent magnet 15 facing the inside of the cylinder 8 are both S poles, and the ends of the left permanent magnet 20 and the right permanent magnet 15 facing the outside of the cylinder 8 are both N poles.

[0149] Furthermore, the left permanent magnet 20 is fixedly installed in the left large drill hole R of the left roller bracket 4, and the right permanent magnet 15 is installed in the right large drill hole T of the right roller bracket 10, and the left permanent magnet 20, the right permanent magnet 15 and the piston shaft 6 are coaxially arranged.

[0150] In one embodiment of this application, the piston shaft 6 is hollow inside, and a stator core 18 is coaxially arranged inside the piston shaft 6. The coil 17 is wound on the stator core 18, and the stator core 18 enhances the magnetic field strength to improve the sensitivity of the flow meter.

[0151] Furthermore, the flow meter also includes a controller connected to the coil 17 for receiving the induced electromotive force acquired by the coil 17. The controller obtains the moving speed of the piston 7 based on the induced electromotive force and further calculates the flow rate based on the moving speed and the effective cross-sectional area of ​​the piston 7.

[0152] Specifically, coil 17 can be connected to a controller outside cylinder 8. The controller can automatically calculate the moving speed of piston 7 based on the output voltage corresponding to the induced electromotive force of coil 17, and further calculate the flow rate based on the moving speed and the effective cross-sectional area of ​​piston 7. The results can be displayed for easy data reading.

[0153] In addition, the controller establishes a correspondence between the output voltage of coil 17 and the moving speed of piston 7 by comparing the output voltage of coil 17 with the moving speed of piston 7. Subsequently, coil 17 transmits the output voltage to the controller, and the controller can obtain the moving speed of piston 7 at this time based on the output voltage.

[0154] Furthermore, the controller can be, but is not limited to, various measuring instruments, data acquisition cards, personal computers, laptops, smartphones, tablets, etc. However, these are not within the scope of protection claimed in the embodiments of this application and will not be discussed further here.

[0155] It should be noted that the moving speed of piston 7 is proportional to the output voltage of coil 17, so the speed error depends on the error of voltage reading, which makes the speed measurement accuracy very high in this embodiment.

[0156] It should be understood that although quantifiers such as "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit.

[0157] The directional terms such as "outer," "middle," and "inner" mentioned or potentially used in this specification are defined relative to the structures shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0158] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of this application, and these improvements and additions should also be considered within the scope of protection of this invention. Any modifications, alterations, and equivalent variations made by those skilled in the art without departing from the spirit and scope of this application, based on the disclosed technical content, are equivalent embodiments of this application. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of this application still fall within the scope of the technical solution of this application.

Claims

1. A piston-type dynamic flow meter integrating a variable flux velocity sensor, characterized in that, Includes a cylinder (8), and a metering cavity is formed inside the cylinder (8). The axial direction is defined as the direction along the central axis of the metering cavity or parallel to the central axis of the metering cavity, and the circumferential direction is defined as the direction around the central axis of the metering cavity. The metering chamber is equipped with a metering unit, and the metering chamber is fed and discharged through the metering unit. The metering unit includes a piston shaft (6) extending along the axial direction and a piston (7) movably sleeved on the piston shaft (6). The piston (7) divides the metering chamber into two volume chambers. The cylinder (8) has an inlet channel and an outlet channel at both ends. During the process of the piston (7) moving back and forth along the axial direction and rotating around the circumference in the metering chamber, the two volume chambers alternately connect the inlet channel and the outlet channel, so that the two volume chambers alternately receive and discharge liquid. The flow meter also includes a speed sensor unit for obtaining the moving speed of the piston (7) along the axial direction. The speed sensor unit includes permanent magnets disposed in the metering cavity and located at both ends of the piston shaft (6) along the axial direction. The permanent magnets form a magnetic field around the piston shaft (6). A coil (17) extending along the axial direction is also wound inside the piston shaft (6). The coil (17) is used to sense the electromotive force of the magnetic field. When the metering chamber is drawing in and draining liquid, the piston (7) moves back and forth along the axial direction on the piston shaft (6), which can change the magnitude of the magnetic flux in the metering chamber. The coil (17) obtains the induced electromotive force of the magnetic field accordingly, so as to obtain the moving speed of the piston (7) based on the induced electromotive force, thereby obtaining the flow rate according to the moving speed of the piston (7) and the effective cross-sectional area of ​​the piston (7).

2. The piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 1, characterized in that, Define one end along the axial direction as the left end and the other end as the right end, and take the direction of the diameter of the cross-section of the cylinder (8) as the radial direction; The left end of the metering chamber is provided with a left roller support seat (4), and the right end of the metering chamber is provided with a right roller support seat (10). The left and right ends of the piston shaft (6) are respectively fixed on the left roller support seat (4) and the right roller support seat (10). The left roller support seat (4) and the piston (7) form a left volume cavity (D) within the cylinder body (8), and the right roller support seat (10) and the piston (7) form a right volume cavity (I) within the cylinder body (8). Both the left roller support (4) and the right roller support (10) are provided with radially extending roller shafts (24) at the end facing the piston (7). Both ends of the roller shaft (24) are rotatably provided with rollers (22, 23), and the rollers (22, 23) on the left roller support (4) and the right roller support (10) are symmetrically arranged with respect to the cross-section of the piston (7). The piston (7) has guide surfaces (M, N) on its left and right ends respectively, which cooperate with the rollers (22, 23). The guide surfaces (M, N) are both axially annular curved surfaces with axial undulations. The projection of the guide surfaces (M, N) on the axial direction is annular. The curved surfaces have two highest points (T1) and two lowest points (T2). The highest points (T1) and the lowest points (T2) are located on two mutually perpendicular diameters of the annulus. The curved surfaces are symmetrical with respect to the two diameters. The undulating waveforms of the guide rail surfaces (M, N) located at both ends of the piston (7) are staggered by 90°. When the rollers (22, 23) roll against the corresponding guide rail surfaces (M, N), they can synchronously drive the piston (7) to rotate circumferentially and move along the axial direction. Two axisymmetric left axial grooves (E) and two axisymmetric right axial grooves (H) are formed on the outer surface of the piston (7). The left axial grooves (E) and the right axial grooves (H) are alternately arranged at equal angles along the circumference on the outer surface of the piston (7). The left axial groove (E) communicates with the left volume cavity (D), and the right axial groove (H) communicates with the right volume cavity (I). The cylinder (8) has a left annular groove (A) at its left end. The cylinder (8) also has two axially symmetrical left axial blind holes (C) on its left wall. The left axial blind holes (C) have a left window (F) that runs through the radial direction. The left window (F) is used to communicate with the left axial groove (E) or the right axial groove (H). The right end of the cylinder (8) is provided with a right annular groove (K), and the wall surface of the right end of the cylinder (8) is also provided with two axially symmetrical right axial blind holes (J). The right axial blind holes (J) are provided with a right window (G) that runs through the radial direction. The right window (G) is used to communicate with the left axial groove (E) or the right axial groove (H). The projections of the left axial blind hole (C) and the right axial blind hole (J) on the cross-section of the cylinder (8) are alternately arranged at equal angles along the circumferential direction; The cylinder body (8) is provided with an inlet (B) and an outlet (L) at its left and right ends respectively; the inlet (B), the left annular groove (A), the left axial blind hole (C), and the left window (F) are connected in sequence to form an inlet channel; the right window (G), the right annular groove (K), the right axial blind hole (J), and the outlet (L) are connected in sequence to form an outlet channel; During the reciprocating and rotating motion of the piston (7) along the axial direction, the left volume chamber (D), the right volume chamber (I), the left axial groove (E), the right axial groove (H), the inlet channel, and the outlet channel have the following corresponding relationships: In the first state: The liquid being tested drives the piston (7) to move to the right along the axial direction, and the piston (7) rotates circumferentially under the force of the rollers (22, 23); the left axial groove (E) is aligned with the left window (F), the right axial groove (H) is aligned with the right window (G), the left volume chamber (D) is fed into the liquid through the connected left axial groove (E) and the liquid inlet channel, and the right volume chamber (I) is discharged into the liquid through the connected right axial groove (H) and the liquid outlet channel; Second state: The piston (7) moves and rotates to the left along the axial direction under the cooperation of the rollers (22, 23) and the guide rail surface (M, N); the left axial groove (E) is not connected to the left window (F) or the right window (G), the right axial groove (H) is not connected to the left window (F) or the right window (G), the left volume chamber (D) neither receives nor discharges liquid, and the right volume chamber (I) neither receives nor discharges liquid; Third state: The liquid being tested drives the piston (7) to move to the left along the axial direction, and the piston (7) rotates circumferentially under the force of the rollers (22, 23); the right axial groove (H) is aligned with the left window (F), and the left axial groove (E) is aligned with the right window (G); the left volume chamber (D) drains through the connected right axial groove (H) and the liquid outlet channel, and the right volume chamber (I) receives liquid through the connected left axial groove (E) and the liquid inlet channel; In the fourth state: The piston (7) moves and rotates to the right along the axial direction under the cooperation of the rollers (22, 23) and the guide rail surface (M, N); the left axial groove (E) is not connected to the left window (F) and the right window (G), the right axial groove (H) is not connected to the left window (F) and the right window (G), the left volume chamber (D) neither receives nor discharges liquid, and the right volume chamber (I) neither receives nor discharges liquid.

3. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 2, characterized in that, The cylinder (8) has a left end cap (1) at its left end and a right end cap (14) at its right end. The left end cap (1) and the right end cap (14) enclose the inner cavity of the cylinder (8) to form the metering cavity. The left roller support seat (4) is axially constrained in the cylinder (8) by the piston (7) and the left end cover (1), and the right roller support seat (10) is axially constrained in the cylinder (8) by the piston (7) and the right end cover (14). A left elastic seal (21) is provided between the left roller bracket seat (4) and the left end cover (1), and a right elastic seal (11) is provided between the right roller bracket seat (10) and the right end cover (14).

4. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 1, characterized in that, The permanent magnet includes a left permanent magnet (20) and a right permanent magnet (15) coaxially disposed at both ends of the piston shaft (6) along the axial direction, wherein the magnetic pole directions of the left permanent magnet (20) and the right permanent magnet (15) are the same.

5. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 4, characterized in that, The left permanent magnet (20) and the right permanent magnet (15) have S poles at the ends facing inwards from the cylinder (8), and N poles at the ends facing outwards from the cylinder (8).

6. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 2, characterized in that, The left roller support seat (4) is coaxially provided with a left stepped through hole, which includes a large left drill hole (R) at the left end and a small left drill hole (Q) at the right end. The right roller support seat (10) is provided with a right stepped through hole coaxially, the right stepped through hole including a right large drill hole (T) at the right end and a right small drill hole (P) at the left end. The left end of the piston shaft (6) is installed in the left small drill hole (Q), and the right end of the piston shaft (6) is installed in the right small drill hole (P). The permanent magnet includes a left permanent magnet (20) coaxially disposed at the left end of the piston shaft (6) and a right permanent magnet (15) coaxially disposed at the right end. The left permanent magnet (20) is disposed in the left large borehole (R) and the right permanent magnet is disposed in the right large borehole (T).

7. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 2, characterized in that, The left roller bracket (4) has a left mounting groove (U) on its right end face for accommodating the corresponding rollers (22, 23), and the right roller bracket (10) has a right mounting groove (V) on its left end face for accommodating the corresponding rollers (22, 23).

8. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 3, characterized in that, A first left sealing ring (3) is provided between the left end cap (1) and the inner wall surface of the cylinder (8), and a first right sealing ring (12) is provided between the right end cap (14) and the inner wall surface of the cylinder (8). A second left sealing ring (2) is provided between the left end cover (1) and the left end face of the cylinder (8), and a second right sealing ring (13) is provided between the right end cover (14) and the right end face of the cylinder (8). A third left sealing ring (19) is provided between the left roller support seat (4) and the piston shaft (6), and a third right sealing ring (16) is provided between the right roller support seat (10) and the piston shaft (6).

9. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 1, characterized in that, A stator core (18) is coaxially arranged inside the piston shaft (6), and the coil (17) is wound on the stator core (18).

10. A piston-type dynamic flow meter with an integrated variable flux velocity sensor as described in claim 1, characterized in that, The flow meter also includes a controller connected to the coil (17) for receiving the induced electromotive force obtained by the coil (17), and for obtaining the moving speed of the piston (7) based on the induced electromotive force, and further calculating the flow rate based on the moving speed and the effective cross-sectional area of ​​the piston (7).

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