Rotary piston type flow meter

Abstract

To provide a rotary piston type flow meter capable of accurately measuring flow rate even when the amount of liquid being measured is minute. [Solution] The rotary piston type flow meter 10 comprises a bottomed and substantially cylindrical measuring chamber 23 having an inlet 24 and an outlet 25 for the liquid to be measured, a rotor 50 that can rotate eccentrically along the inner surface of the measuring chamber 23, a magnet 55 that moves integrally with the rotor 50, and a magnetic sensor 63 that detects the magnet 55. A circular guide hole 27 is formed in the center of the bottom of the measuring chamber 23, the rotor 50 is made of a substantially disc-shaped solid member with a thickness approximately the same as the depth of the measuring chamber 23, and a guide shaft 52 is formed in the center of the rotor 50 that is inserted through the guide hole 27. Preferably, an eccentric bearing 40 that pivotally supports the guide shaft 52 is rotatably housed inside the guide hole 27.

Description

Technical Field

[0001] The present invention relates to a rotary piston type flowmeter that detects the rotation of a rotor that rotates according to the flow rate of a liquid to be measured in a measurement chamber and measures the flow rate of the liquid to be measured from the number of rotations thereof.

Background Art

[0002] Conventionally, positive displacement flow meters have been used to accurately measure the flow rate of a liquid to be measured flowing through piping installed in various plants and equipment. Among these, the rotary piston type flow meter A100 (hereinafter referred to as flow meter A100) described in Patent Document 1 is frequently used for measuring small to minute flow rates of liquids to be measured. As shown in Figure 10, this type of flow meter A100 has a lower body A110 into which an inlet path A111 and an outlet path A112 to which an inlet-side connecting pipe and an outlet-side connecting pipe are connected, and a metering chamber A113 continuous with these inlet path A111 and outlet path A112 are formed, an upper body A120 that closes the upper opening of the metering chamber A113, and a rotor A130 that oscillates and rotates while moving along the inner wall of the metering chamber A113. At the center of the measuring chamber A113, an annular projection A114 and a central axis A115 provided around the annular projection A114 form an annular guide groove A116. Furthermore, as shown in Figure 11, a partition plate A117 is installed in the measuring chamber 113, extending from the inner circumferential surface of the measuring chamber A113 to the outer circumferential surface of the annular projection A114, and blocking the space between the inlet path A111 and the outlet path A112. In addition, the rotor A130 is configured as a bottomed cylindrical shape with a disc portion A132 at the upper end of a cylindrical body A131, and at the center of the disc is a mounting portion A133 for a magnet A135 that protrudes upward and a guide shaft A134 that protrudes downward. The rotor A130 is housed in the metering chamber A113 with the guide shaft A134 inserted into the guide groove A116, and the rotor A130 oscillates within the metering chamber A113 as the guide shaft A134 rotates along the guide groove A116. Therefore, when the liquid to be measured enters the metering chamber A113 from the inflow path A111, the inflow pressure of the liquid causes the rotor A130 to rotate toward the outlet, and the liquid to be measured in the metering chamber A113 is sent out of the outlet to the outflow path A112.

[0003] Furthermore, the upper body A120 is provided with a relief groove A121 for the mounting portion A133 to rotate, and is equipped with a magnetic sensor A122 capable of detecting the magnet A135 attached to the mounting portion A133. In this way, each time the rotor A130 rotates, a predetermined amount of the liquid to be measured is sent to the outflow path A112, and the magnet is detected once by the magnetic sensor A122. Therefore, the flow rate can be calculated from the product of the rotation speed of the rotor A130 measured by the magnetic sensor A122 and the amount of discharged per rotation of the rotor A130. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 05-142010 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional rotary piston flow meters, when designed to measure minute amounts of liquid, require a reduced volume of the measuring chamber and rotor, resulting in a very thin rotor. This leads to problems such as breakage due to wear and impact, and deformation due to inability to withstand the pressure of high-pressure or high-viscosity liquids. On the other hand, if the rotor's disc and cylindrical parts are thickened to ensure strength, the rotor becomes heavy, making it impossible to rotate with the pressing force of a minute amount of liquid. Thus, conventional rotary piston flow meters have limitations in their size reduction, resulting in the inability to accurately measure minute flow rates.

[0006] Therefore, the present invention aims to provide a rotary piston type flow meter capable of measuring even minute flow rates of liquids under test. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a rotary piston type flow meter comprising a bottomed and substantially cylindrical measuring chamber having an inlet and outlet for the liquid to be measured, a rotor that can rotate eccentrically along the inner surface of the measuring chamber, a magnet that moves integrally with the rotor, and a magnetic sensor that detects the magnet, wherein a circular guide hole is formed in the center of the bottom of the measuring chamber, the rotor is made of a substantially disc-shaped solid member, and a guide shaft is formed in the center of the rotor that is inserted through the guide hole. Furthermore, it is preferable that an eccentric bearing, which supports the guide shaft, is rotatably housed inside the guide hole. Furthermore, it is preferable that a U-shaped retaining groove is formed on the outer circumference of the eccentric bearing in plan view, and that the guide shaft is rotatably supported by being sandwiched between the inner surfaces of the retaining groove and the guide hole. Furthermore, it is preferable that the rotor is provided with a housing hole for housing the magnet at a predetermined distance from the center of the rotor, and that the magnet housed in the housing hole moves in an elliptical orbit in accordance with the oscillating rotation of the rotor. Furthermore, it is preferable that the magnetic sensor is arranged in a manner that allows for the detection of the magnet reaching the end of the elliptical orbit on the major axis side. Furthermore, it is preferable that the metering chamber is provided with a partition plate between the inlet and outlet, and that the rotor has a notch through which the partition plate is inserted, and that the notch and the partition plate are always in contact at one or more points, so that the rotor rotates eccentrically within the metering chamber while blocking the space between the inlet and outlet. Furthermore, it is preferable that the rotor has a notch through which the partition plate can be inserted, and that the diameter of the rotor is set to be at least 5 times and no more than 10 times the width of the partition plate. In particular, it is preferable that the diameter of the rotor is set to a dimension of 6 times or more and 7 times or less the width of the partition plate. Furthermore, the device comprises a lower body with a weighing chamber formed on its upper surface, and an upper body that abuts against the upper surface of the lower body and closes the upper opening of the weighing chamber. Preferably, one of the lower or upper body has a sealing groove formed on the contact surface with the other, surrounding the outer circumference of the weighing chamber, and a sealing member is enclosed in the sealing groove to seal the gap between the lower body and the upper body. [Effects of the Invention]

[0008] The above invention features a rotor that is approximately the same thickness as the depth of the metering chamber and has a substantially disc shape, without a cylindrical portion. Therefore, even when it shrinks, the rotor does not become excessively thin, preventing insufficient strength, and the rotor does not become heavy, allowing it to rotate even at minute flow rates. As a result, it is possible to reduce the size of the rotor and metering chamber, and there are advantages such as being able to accurately measure flow rates even at minute flow rates. Furthermore, since the eccentric bearing is positioned inside the guide hole formed in the measuring chamber, there is virtually no void inside the guide hole through which the liquid to be measured can enter. As a result, measurement errors caused by the liquid entering this void are eliminated, leading to advantages such as improved measurement accuracy. Furthermore, since the magnet is positioned eccentrically from the center of the rotor and moves in an elliptical orbit in accordance with the rotor's oscillating rotation, the magnet can be moved over a relatively long distance even if the rotor and metering chamber are reduced in size. This has advantages such as preventing sensing errors and enabling accurate measurement of the rotor's rotational speed. Furthermore, by setting the rotor diameter to be at least 5 times and no more than 10 times the width of the partition plate, the rotor rotates easily, and accurate flow rate measurement is possible, among other advantages. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of the rotary piston type flow meter according to the present invention. [Figure 2] This is an exploded perspective view of the rotary piston type flow meter according to the present invention. [Figure 3]It is a plan view showing the structure of the lower body of the rotary piston type flowmeter according to the present invention. [Figure 4] It is a sectional view taken along the line A-A of FIG. 3. [Figure 5] It is an enlarged view of part C of FIG. 4. [Figure 6] It is an enlarged view of part B of FIG. 3. [Figure 7] It is an enlarged view of part B showing the state shifted to the next state from FIG. 6. [Figure 8] It is an enlarged view of part B showing the state shifted to the next state from FIG. 7. [Figure 9] It is an enlarged view of part B showing the state shifted to the next state from FIG. 8. [Figure 10] It is a side sectional view showing the structure of a conventional flowmeter. [Figure 11] It is a plan view showing the structure of a conventional flowmeter.

Mode for Carrying Out the Invention

[0010] Hereinafter, a rotary piston type flowmeter 10 (hereinafter referred to as the flowmeter 10) according to an embodiment of the present invention will be described based on the drawings. As shown in FIG. 1, this flowmeter 10 has a lower body 20 to which an inflow side connection pipe (not shown) and an outflow side connection pipe (not shown) are connected, and an upper body 60 fixed to the lower body 20.

[0011] On the upper surface of the lower body 20, a fitting recess 21 that can be fitted with the upper body 60 is formed as shown in FIG. 3. At the bottom of this fitting recess 21, an annular seal groove 22 and a metering chamber 23 located inside the seal groove 22 are formed so as to open upward. A ring-shaped seal member 221 is accommodated in the seal groove 22. Thereby, as shown in FIG. 4, when the upper body 60 is fixed above the lower body 20, the space between the lower body 20 and the upper body 60 is sealed by the seal member 221. For this reason, the measured liquid supplied into the metering chamber 23 is prevented from flowing out to the outside.

[0012] As shown in Figures 2 and 3, the measuring chamber 23 is a space configured in a substantially cylindrical shape. An inlet 24 and an outlet 25 are formed on the bottom surface 231 of the measuring chamber 23, and an inlet path 241 and an outlet path 251 are continuous to these inlet 24 and outlet 25, respectively. These inlet path 241 and outlet path 251 are continuous to the outer surface of the lower body 20, and connection parts 242 and 252 are formed at the outer openings thereto to which the inlet-side connecting pipe (not shown) and the outlet-side connecting pipe (not shown) are connected.

[0013] As shown in Figure 6, a partition plate 30 is provided between the inlet 24 and the outlet 25 in the measuring chamber 23. This partition plate 30 is a plate-shaped member that extends radially inward from the inner wall 232 of the measuring chamber 23, and is designed so that its thickness is approximately the same as the depth of the measuring chamber 23. Therefore, the liquid to be measured that flows into the measuring chamber 23 from the inlet 24 flows around the partition plate 30 and flows out from the outlet 25. The partition plate 30 is sandwiched in a groove 233 formed in the inner wall 232 of the measuring chamber 23, and is fixed by inserting a fixing pin 26 that is erected at the bottom of the groove 233 of the measuring chamber 23. As the partition plate 30 is sandwiched in the groove 233 and the fixing pin 26 is inserted through it, the partition plate 30 will not shift position even when subjected to the pressure of the liquid being measured or vibrations caused by the rotation of the rotor 50 described later. Furthermore, the partition plate 30 can be easily replaced. In addition, the radial inner end of the partition plate 30 is configured in an arc shape, so when the inner circumference of the notch 53 of the rotor 50 described later comes into contact with the inner end of the partition plate 30, it is less likely to get caught and the rotor 50 can slide smoothly.

[0014] Further, as shown in FIGS. 5 and 6, a circular guide hole 27 is formed at the center of the bottom surface 231 of the metering chamber 23. A guide pin 28 is erected at the center of the bottom of the guide hole 27, and an annular space is formed inside the guide hole 27 by the guide pin 28. A substantially cylindrical eccentric bearing 40 rotatably supported by the guide pin 28 is accommodated in the annular space. A holding groove 41 extending in the axial direction is formed by notching on the outer peripheral surface of the eccentric bearing 40. The holding groove 41 is configured in a substantially U shape in plan view, and is configured such that the circumferential width thereof is substantially the same as the maximum portion of the radial gap generated between the holding groove 41 and the guide hole 27. Therefore, a guide shaft 52 described below inserted into the holding groove 41 is held so as not to incline by the U-shaped portion of the holding groove 41 and the inner peripheral surface of the guide hole 27.

[0015] As shown in Figures 6 to 9, the weighing chamber 23 of the above structure houses a rotor 50 that can swing and rotate along the inner wall 232. The rotor 50 consists of a solid disc portion 51 whose plate thickness is approximately the same as the depth dimension of the weighing chamber 23, and a cylindrical guide shaft 52 that protrudes from the center of the lower surface of the disc portion 51. The guide shaft 52 is fitted into the retaining groove 41 of the eccentric bearing 40 and is rotatably held by the retaining groove 41 and the inner circumferential surface of the guide hole 27. Furthermore, the disc portion 51 of the rotor 50 is provided with a notch 53 through which the partition plate 30 can be inserted. This notch 53 is designed so that when the guide shaft 52, which is directed by the eccentric bearing 40, revolves within the guide hole 27, it does not bite into the partition plate 30, and at least one point of contact is always maintained, and the disc portion 51 does not completely close the inlet 24 and outlet 25. Because the notch 53 is fitted into the partition plate 30 in this way, when the guide shaft 52 revolves within the guide hole 27, the disc portion 51 swings around the partition plate 30 as shown in Figures 6 to 9. Furthermore, because the disc portion 51 of the rotor 50 and the partition plate 30 constantly block the space between the inlet 24 and the outlet 25, the liquid to be measured that flows into the metering chamber 23 through the inlet 24 pushes the rotor 50 toward the outlet 25, causing the rotor 50 to oscillate within the metering chamber 23. In addition, the notch 53 is configured such that its opening is the width L2 of the partition plate 30. Therefore, as shown in Figure 8, even when the rotor 50 is furthest from the partition plate 30, the area near the opening of the notch 53 and the partition plate 30 are in contact, and the space between the inlet 24 and the outlet 25 can be continuously blocked.

[0016] Furthermore, as shown in Figure 6, a housing hole 54 is formed through the disc portion 51 of the rotor 50 at a position away from the notch 53, and a magnet 55 is housed in this housing hole 54. Because the housing hole 54 is formed at an eccentric position from the center of the rotor 50, when the rotor 50 oscillates, the magnet 55 moves in an elliptical orbit having a major axis L4 that is longer than the diameter L3 of the circular orbit of the guide shaft 52, as shown by the dashed line in Figure 9. It is preferable that the dimension of the major axis L4 of the elliptical orbit is 1.3 times or more the dimension of the diameter L3 of the circular orbit. In addition, the magnet 55 is made slightly thinner than the rotor 50 so as not to get caught on the upper body 60 or the bottom surface 231 of the weighing chamber 23 when the rotor 50 oscillates.

[0017] Furthermore, the diameter L1 of the rotor 50 is designed to be 5 to 10 times the width L2 of the partition plate 30. Because the diameter L1 of the rotor 50 is designed to be 5 times or more the width L2 of the partition plate 30, when the rotor 50 is oscillating, the notch 53 is continuous with both the inlet 24 and the outlet 25, and the partition plate 30 does not block the space between the inlet 24 and the outlet 25, thus preventing a decrease in measurement accuracy. In other words, because the diameter L1 of the rotor 50 is 5 times or more the width L2 of the partition plate 30, the liquid being measured does not pass directly from the inlet 24 to the outlet 25, thus preventing a decrease in measurement accuracy. On the other hand, if the diameter L1 of the rotor 50 is designed to be 10 times or less the width L2 of the partition plate 30, the notch 53 through which the partition plate 30 is inserted will be relatively large relative to the diameter L1 of the rotor 50. In particular, when the diameter L1 of the rotor 50 is designed to be 6 to 7 times the width L2 of the partition plate 30, the notch 53 becomes wider than the diameter L1 of the rotor 50, and the space between the inlet 24 and the outlet 25 is blocked by the partition plate 30 and the rotor 50. As a result, the rotor 50 can rotate smoothly even when the flow rate of the liquid being measured is minute. Consequently, when the diameter L1 of the rotor 50 is designed to be 6 to 7 times the width L2 of the partition plate 30, the flow rate of the liquid being measured can be measured with particularly high accuracy.

[0018] The upper body 60 has a fitting projection 61 formed on its lower surface that fits into a fitting recess 21 of the lower body 20, while a bottomed sensor housing 62 is formed on its upper surface. A magnetic sensor 63 is housed in the bottom of this sensor housing 62, as shown in Figure 2, and the magnetic sensor 63 is positioned so that its detection range 64 is located near the vertex on the major axis side of the elliptical orbit of the magnet 55. The magnetic sensor 63 is connected to a display device (not shown) that measures the flow rate of the liquid being measured, and is configured to output a pulse signal to the display device each time the magnet 55 reaches the detection range 64, as shown in Figure 7. The bottom of the sensor housing 62 is set to a thickness that allows the magnetic sensor 63 to detect the magnet 55 mounted on the rotor 50 and does not deform due to the pressure of the liquid being measured.

[0019] The display device includes a storage unit that stores in advance a set discharge amount of the liquid to be measured that is discharged each time the rotor 50 oscillates once, a counter that counts the number of rotations of the rotor 50 from the number of pulse signals from the magnetic sensor 63, and a display screen that calculates and displays the total flow rate of the liquid to be measured from the product of the set discharge amount and the number of rotations of the rotor 50.

[0020] The operation of the flow meter 10, configured as described above, will be explained below. The liquid to be measured, supplied from the inlet piping, flows into the metering chamber 23 through the inlet path 241 and the inlet 24. At this time, since the inlet 24 and the outlet 25 are separated by the rotor 50, the liquid to be measured that has flowed into the metering chamber 23 presses against the outer surface of the rotor 50. As a result, the rotor 50 is pushed towards the outlet 25, and as shown in Figures 6 to 9, the guide shaft 52 revolves along the guide hole 27 and swings around the partition plate 30 while constantly blocking the space between the inlet 24 and the outlet 25. At this time, the liquid to be measured that had accumulated inside the metering chamber 23 is pressed by the swinging rotor 50 and flows out into the outlet piping through the outlet 25 and the outflow path 251.

[0021] When the liquid to be measured flows in, each time the guide shaft 52 rotates once and the rotor 50 oscillates once, the magnet 55 attached to the rotor 50 passes through the detection range 64, and the magnetic sensor 63 transmits a pulse signal to the display device. Therefore, the display device can detect the number of oscillations of the rotor 50 from the received pulse signal, and can calculate and display the flow rate of the liquid to be measured from the product of the set discharge amount and the number of pulse signals.

[0022] When the rotor 50 oscillates, the magnet 55 is eccentrically positioned away from the partition plate 30 and guide shaft 52, which are the center of the rotor 50's oscillation. As a result, the magnet 55 moves along an elliptical path with a major axis L4 that is longer than the diameter L3 of the circular path of the guide shaft 52, as shown in Figure 9. This allows the magnet 55 to move back and forth between the detection range 64 of the magnetic sensor 63, as shown in Figure 7, and a position sufficiently far from the detection range 64 of the magnetic sensor 63, as shown in Figure 9. Consequently, sensing defects such as the magnetic sensor 63 constantly detecting the magnet 55 can be prevented. In other words, because the magnet 55 is eccentrically positioned from the guide shaft 52, the flow meter 10 of this invention has the effect of reducing the travel distance of the magnet 55 compared to when the magnet 55 is on the guide shaft 52, thus reducing the likelihood of sensing defects. As a result, it is possible to reduce the size of the metering chamber 23 and the rotor 50 compared to the conventional flow meter A100, and it becomes possible to measure even minute flow rates.

[0023] In the flow meter 10 with the above structure, the rotor 50 has a solid structure consisting of a disc portion 51 and a guide shaft 52 protruding from the lower surface of the disc portion 51, so that a guide hole 27 can be provided in the bottom surface 231 of the metering chamber 23. This eliminates the cylindrical body A131 and the annular projection A114 located inside the cylindrical body A131, which are prone to damage when the conventional flow meter A100 is scaled down. Furthermore, since the rotor 50 does not have a cylindrical body A131, the disc portion 51 that is pressed by the liquid being measured has a thickness dimension that is approximately the same as the depth of the metering chamber 23, making it possible to have higher strength compared to the rotor A130 of the conventional flow meter A100. Thus, because the rotor 50 of the flow meter 10 of the present invention has a solid structure, when scaled down there are no excessively thin and weak parts, and it has the effect of being less prone to damage and wear during operation.

[0024] Furthermore, since the magnet 55 is housed in a housing hole 54 formed in the disc portion 51 of the rotor 50 rather than in the mounting portion A133, it is possible to maintain the size of the magnet 55 even when the rotor 50 is reduced in size, and there is no risk of the magnet 55 coming off the rotor 50 when the rotor 50 is oscillating.

[0025] Furthermore, since the rotor 50 does not have a cylindrical section A131, the metering chamber 23 can be designed to be shallower by the amount of the cylindrical section A131. This reduces the volume of the metering chamber 23, making it possible to measure even minute flow rates. In addition, because the metering chamber 23 is designed to be shallow, the radial dimensions of the metering chamber 23 and rotor 50 can be increased compared to a conventional flow meter A100 designed with the same volume. As a result, the outer surface of the rotor 50, which is pressed by the liquid being measured, and the guide pin 28, which is the center of the rotor 50's oscillating rotation, are separated. Therefore, even a small force from the liquid being measured with an extremely small flow rate can cause the rotor 50 to oscillate smoothly, resulting in more accurate measurements. Moreover, the notch 53 of the rotor 50 is configured to be relatively large, and the inner surface of the notch 53 is also wide, so the inner surface of the notch 53 is also more easily subjected to pressure from the liquid being measured. Therefore, the rotor 50 can oscillate more smoothly.

[0026] Furthermore, since the rotor 50 does not have a mounting portion A133, the relief groove A121, which would cause the mounting portion A133 to rotate, can be eliminated. Also, since the eccentric bearing 40 is housed in the guide hole 27, there is almost no void in the guide hole 27 through which the liquid to be measured can enter. As a result, measurement errors caused by the liquid to be measured flowing into the relief groove A121 and guide groove A116, which were a problem with conventional flow meters A100, do not occur, and flow rate measurement can be performed with high accuracy.

[0027] Furthermore, the specific configuration of each part is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. For example, the inflow direction of the liquid to be measured and the eccentric rotation direction of the rotor 50 can be in the opposite direction to those of the embodiments described above without any problem. In addition, the rotary piston type flow meter 1 according to the present invention can measure the flow rate of water, oil, and various chemical solutions, and by pre-setting the discharge amount according to the type of liquid to be measured, it is possible to measure the flow rate of various liquids to be measured. [Explanation of symbols]

[0028] 10… Rotary piston type flow meter 20 … Lower body 23…Measuring room 231… Bottom 24 … Inlet 25 … Outlet 27 … Guide hole 28… Guide pin 30… Partition plate 40... Eccentric bearing 41 … Retaining groove 50… Rotor 51 ... Disc section 52… Guide axis 53… trigger 54 ... Intake 55… Magnet 60… Upper body 63… Magnetic sensor

Claims

1. A measuring chamber with a closed bottom and a roughly cylindrical shape, having an inlet and outlet for the liquid to be measured, A rotor that can rotate eccentrically along the inner surface of the measuring chamber, A magnet that moves integrally with the rotor, A rotary piston type flow meter equipped with a magnetic sensor for detecting the aforementioned magnet, A circular guide hole is formed in the center of the bottom of the aforementioned weighing chamber. The rotary piston type flow meter is characterized in that the rotor is made of a solid member in the shape of a substantially circular disc, and a guide shaft is formed in the center of the rotor, which is inserted through the guide hole.

2. The rotary piston type flow meter according to claim 1, characterized in that an eccentric bearing for supporting the guide shaft is rotatably housed inside the guide hole.

3. A retaining groove with a U-shape in plan view is formed on the outer circumference of the aforementioned eccentric bearing. The rotary piston type flow meter according to claim 2, characterized in that the guide shaft is rotatably supported by being sandwiched between the inner surfaces of the retaining groove and the guide hole.

4. The rotary piston type flow meter according to claim 1, characterized in that the rotor is provided with a housing hole for housing the magnet at a predetermined distance from the center of the rotor, and the magnet housed in the housing hole moves in an elliptical orbit in accordance with the oscillating rotation of the rotor.

5. The rotary piston type flow meter according to claim 4, characterized in that the magnetic sensor is arranged to detect when the magnet has reached the end on the major axis side of the elliptical orbit.

6. The weighing chamber is provided with a partition plate between the inlet and the outlet, The rotor has a notch through which the partition plate is inserted. The rotary piston type flow meter according to claims 1 to 5, characterized in that the rotor rotates eccentrically within the measuring chamber while blocking the space between the inlet and outlet, as the notch and the partition plate are configured to be in contact at one or more points at all times.

7. The rotor has a notch through which the partition plate can be inserted, The rotary piston type flow meter according to claim 6, characterized in that the rotor has a diameter that is five times or more and ten times or less the width of the partition plate.

8. The rotary piston type flow meter according to claim 7, characterized in that the diameter of the rotor is set to a dimension of 6 times or more and 7 times or less the width of the partition plate.

9. The lower body has the aforementioned measuring chamber formed on its upper surface, It comprises an upper body that abuts against the upper surface of the lower body and closes the upper opening of the weighing chamber, One of the lower or upper body has a sealing groove formed on its contact surface with the other, which surrounds the outer circumference of the measuring chamber. The rotary piston type flow meter according to claim 1 to 5, characterized in that a sealing member is enclosed in the seal groove to seal the gap between the lower body and the upper body.

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