Variable viscosity flow resistance mechanism

Abstract

To provide a variable viscous flow resistance structure which belongs to a technical field of a viscous flow resistance, the structure realizing a change of a flow resistance feature curve by overlapping a rotational inertia of a fluid without changing a feature variable unique to the flow resistance structure.SOLUTION: The variable viscous flow resistance structure includes two or more surfaces. In the resistance structure, one or more gap passages are formed between different surfaces, an external fluid flows in the gap passage, and at least one of an upper side surface and a lower side surface of the gap passage rotates.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention belongs to the technical field of viscous flow resistance and relates to a variable viscous flow resistance structure.

Background Art

[0002] When a fluid passes through a solid wall, due to the viscosity of the fluid, viscous friction occurs between the fluid and the solid wall. The structure where viscous friction occurs is called a viscous flow resistance structure. The viscous flow resistance structure and its viscous friction are important factors that affect the movement of the fluid. General viscous flow resistance structures include pipelines, porous materials, narrow gaps, etc. In actual applications, the viscous flow resistance structure often plays a negative role. For example, during the transportation of tap water, oil, and natural gas, due to the viscous friction of the pipeline, large pressure losses and energy dissipation occur during the process. However, the viscous flow resistance structure also has some positive applications. For example, the invention patent with application number CN202210083296.2 processes a rectangular channel on a cylinder to construct a narrow gap, and then measures the flow rate by utilizing the linear relationship between the flow rate and the pressure difference of the narrow gap.

[0003] The flow resistance characteristic curve, which is the relationship curve between flow rate and pressure difference (the pressure difference being the difference between the upstream pressure and the downstream pressure in a viscous flow resistance structure), depends on intrinsic characteristic variables, such as the magnitude of the flow resistance, the viscosity of the fluid, and its density. Typically, methods for changing the flow resistance characteristic curve involve changing these intrinsic characteristic variables. The invention patent in application number CN202210083296.2 allows for changing the height of a gap passage by changing the width of a rectangular channel, thereby changing the flow resistance when the fluid flows through the gap passage. As shown in Figure 1, as the gap height increases, the flow resistance characteristic curve is deflected downward, and as the gap height decreases, the flow resistance characteristic curve is deflected upward. Another example, CN103807502A, proposes a different method for changing the flow resistance characteristic curve. When a fluid flows through a porous material, the present invention achieves the objective of changing the flow resistance characteristic curve by changing the fluid temperature, viscosity, and density of the fluid by heating the porous material.

[0004] This invention proposes a novel viscous flow resistance structure that achieves changes in the flow resistance characteristic curve by superimposing the rotational inertia of the fluid, without requiring any modification of the intrinsic characteristic variables of the fluid or the flow resistance structure. [Overview of the project] [Problems that the invention aims to solve]

[0005] The objective of the present invention is to propose a variable viscous flow resistance structure that changes the flow resistance characteristics by superimposing rotation, without requiring any changes to the inherent characteristic attributes of the fluid or structure, taking into account the shortcomings of the prior art. [Means for solving the problem]

[0006] The technical solutions employed by this invention are as follows:

[0007] A variable viscosity flow resistance structure comprising two or more surfaces, with one or more gap passages formed between different surfaces, wherein an external fluid flows through the gap passages, and at least one of the upper and lower surfaces of the gap passages rotates.

[0008] In the above technical solution, the external fluid may further be configured to flow in from the inner circumferential end face of the gap passage and flow out from the outer circumferential end face.

[0009] Furthermore, the external fluid may flow in from the outer circumferential end face of the gap passage and flow out from the inner circumferential end face. Here, the inner and outer circumferential end faces are defined as the end face of the gap passage that is closer to the center of rotation, and the other end face, which is the outer circumferential end face.

[0010] Furthermore, the upper and lower surfaces of the gap passage are connected by a spacer and rotate as a single unit.

[0011] Furthermore, in the viscous flow resistance structure, a plurality of gap passages are formed, and the outer circumferential end faces of the plurality of gap passages are in communication with each other, as are the inner circumferential end faces.

[0012] Furthermore, the viscous flow resistance structure further includes at least one switching valve, which is connected to the inner and outer circumferential end faces of the gap passage, and to either the upstream or downstream side of the external fluid, and the switching valve changes the flow direction within the gap passage by switching the connection state between the upstream and downstream of the external fluid and the inner and outer circumferential end faces of the gap passage.

[0013] Furthermore, the viscous flow resistance structure further includes at least one pressure difference sensor for measuring the pressure difference at two different radial positions within the gap passage.

[0014] A variable viscosity flow resistance structure comprising a housing, a motor, and at least one disk, wherein the housing has a first housing opening and a second housing opening, the disk is provided within the housing, a gap passage is formed between the upper surface of the disk and the inner surface of the housing, the motor is mounted on the housing, the motor shaft is connected to and fixed to the disk and rotates the disk, the upstream or downstream of an external fluid is connected to the outer circumferential end face of the gap passage via the first housing opening, and the corresponding downstream or upstream is connected to the inner circumferential end face of the gap passage via the second housing opening.

[0015] A variable viscosity flow resistance structure comprising a housing, a motor, and at least two disks, wherein the housing has a first housing opening and a second housing opening, the disks are provided within the housing and are integrally fixed to each other by spacers, thereby forming a gap passage between the disks, the shaft of the motor passes through the housing and is connected to the disks, and rotates the disks, the upstream or downstream of an external fluid is connected to the outer circumferential end face of the gap passage via the first housing opening, and the corresponding downstream or upstream is connected to the inner circumferential end face of the gap passage via the second housing opening.

[0016] A flow sensor comprising any of the variable viscous flow resistance structures described above. [Effects of the Invention]

[0017] By adopting the structure of the present invention, it is possible to adjust the viscous fluid resistance without changing the inherent characteristics of the fluid or the structure. Furthermore, the overall structure has fewer components, making it easy to process and giving it high potential for future applications in fields such as flow rate measurement. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of the flow resistance characteristic curve of the gap passage. In the diagram, line a' represents a decrease in gap height relative to line a, and line a'' represents an increase in gap height relative to line a. [Figure 2] It is a schematic diagram of the principle of a specific viscous flow resistance structure of the present invention. [Figure 3] It is a schematic diagram of an example of the flow of fluid in the structure of FIG. 2. In the figure, the fluid flows in from the outer peripheral end face of the gap passage and flows out from the inner peripheral end face of the gap passage. [Figure 4] It is a schematic diagram of the flow resistance characteristic curves in two cases when the second disk rotates and does not rotate in the example of FIG. 3. In the figure, line a is the case of non-rotation, and a' is the case of rotation. [Figure 5] It is a schematic diagram showing an example of the flow of fluid in the structure of FIG. 2. In the figure, the fluid flows in from the inner peripheral end face of the gap passage and flows out from the outer peripheral end face of the gap passage. [Figure 6] It is a schematic diagram of the flow resistance characteristic curves in two cases when the second disk rotates and does not rotate in the example of FIG. 5. In the figure, line a is the case of non-rotation, and a' is the case of rotation. [Figure 7] It is a schematic diagram of an apparatus of a specific viscous flow resistance structure of the present invention. [Figure 8] It is a schematic diagram of the principle of another specific viscous flow resistance structure of the present invention. [Figure 9] It is a schematic diagram of the flow resistance characteristic curves in various cases in the structure of FIG. 8. The external fluid flows in from the outer peripheral end face of the gap and flows out from the inner peripheral end face. In the figure, line a is the case of non-rotation, a' is the case where one surface rotates, and a'' is the case where two surfaces rotate. [Figure 10] It is a schematic diagram of the flow resistance characteristic curves in various cases in the structure of FIG. 8. The external fluid flows in from the inner peripheral end face of the gap and flows out from the outer peripheral end face. In the figure, line a is the case of non-rotation, a' is the case where one surface rotates, and a'' is the case where two surfaces rotate. [Figure 11] It is a schematic diagram of an apparatus of another viscous flow resistance structure of the present invention. [Figure 12] It is a schematic diagram of an apparatus of yet another specific viscous flow resistance structure of the present invention. [Figure 13]It is a schematic diagram of the flow resistance characteristic curves in various cases in the example of FIG. 12. In the figure, line a is the case of non-rotation, a' is the situation where A and D, and B and C of the switching valve are in communication, and a'' is the situation where A and C, B and D of the switching valve are in communication. [Figure 14] It is a schematic diagram of the principle of another specific viscous flow resistance structure of the present invention, and there are a plurality of gap passages in this structure. [Figure 15] It is a comparison of schematic diagrams of flow resistance characteristic curves when h = h' in the structure of FIG. 14. In the figure, line a is the case of non-rotation when there is only one gap passage, a' is the case of rotation when there is only one gap passage, line b is the case of non-rotation when there are three gap passages, and b' is the case of rotation when there are three gap passages. [Figure 16] It is a comparison of schematic diagrams of flow resistance characteristic curves when h > h' in the structure of FIG. 14. In the figure, line a is the case of non-rotation when there is only one gap passage, a' is the case of rotation when there is only one gap passage, line b is the case of non-rotation when there are three gap passages, and b' is the case of rotation when there are three gap passages. [Figure 17] It is a schematic diagram of the range of flow rate measurement using the pressure difference of the viscous flow resistance structure. [Figure 18a] It is a schematic diagram of the structure of the flow meter of the present invention. [Figure 18b] It is a schematic diagram of the structure of another flow meter of the present invention. [Figure 19] It is a schematic diagram of the flow resistance characteristic curves in various cases in the example of FIG. 18a or FIG. 18b. The external fluid flows in from the outer peripheral end face of the gap and out from the inner peripheral end face. In the figure, line a is the case of non-rotation, and a' is the case where the disk rotates at a certain rotational speed. [Figure 20] It is a schematic diagram of the flow resistance characteristic curves in various cases in the example of FIG. 18a or FIG. 18b. The external fluid flows in from the inner peripheral end face of the gap and out from the outer peripheral end face. In the figure, line a is the case of non-rotation, and a' is the case where two disks rotate at the same certain rotational speed.

Embodiments for Carrying Out the Invention

[0019] The technical solutions of the present invention will be described in more detail below with reference to the drawings and specific embodiments.

[0020] Example 1 Figure 2 is a schematic diagram of a viscous flow resistance structure. The viscous flow resistance structure consists of two disks. A certain distance is provided between the lower surface of the first disk 1 and the upper surface of the second disk 2, forming a gap passage 3. A communication hole 4 is provided at the center of the first disk 1, which connects the inner circumferential end surface of the gap passage to the external fluid. The first disk 1 remains fixed. The second disk 2 is connected to a rotating shaft 5. The rotating shaft 5 outputs rotational power to rotate the second disk 2.

[0021] The external fluid flows into the gap passage 3 from one end face and out from the other end face. The fluid flow is subjected to viscous frictional resistance at the upper and lower surfaces of the gap passage. Furthermore, the fluid is driven by the second disk 2, generating a circumferential velocity. Figure 3 shows one specific example of the flow. The upstream end of the external fluid is connected to the outer circumferential end face O of the gap passage, and the downstream end of the external fluid is connected to the inner circumferential end face I of the gap passage. Therefore, the fluid flows in from the outer circumferential end face and out from the inner circumferential end face. The fluid forms a fluid flow from the outer to the inner circumferential direction within the gap passage. The fluid flow is mainly subjected to the following two forces: One is the viscous frictional resistance at the upper and lower surfaces of the gap passage, which creates a pressure difference (hereinafter abbreviated as viscous pressure) in the radial direction of the gap passage due to this viscous frictional force. The other is the centrifugal inertial force generated by the circumferential velocity, which creates a pressure difference (hereinafter abbreviated as centrifugal pressure difference) in the radial direction of the gap passage due to this centrifugal inertial force. Centrifugal inertia and viscous friction resistance have the same direction (outward along the radial direction), and the viscous pressure difference and centrifugal pressure difference are in a superposition relationship. Therefore, the pressure difference in the gap passage is the sum of the viscous pressure difference and the centrifugal pressure difference. In this invention, the pressure difference in the gap passage refers to the value obtained by subtracting the pressure at the end face from the pressure at the end face from the pressure at the end face from which the fluid flows in. For example, in Figure 3, the pressure difference in the gap passage is the difference between the pressure at the outer end face and the pressure at the inner end face.

[0022] Figure 4 compares the flow resistance characteristic curves in the example of Figure 3, specifically for the case where the second disk 2 is rotating and the case where it is not rotating. Because a centrifugal pressure difference is superimposed, the rotation of the second disk 2 causes the flow resistance characteristic curve to shift upward. The faster the rotation speed of the second disk 2, the faster the peripheral velocity of the fluid, and the greater the degree of upward shift of the flow resistance characteristic curve. The intersection of the flow resistance characteristic curve and the pressure difference axis is called the zero flow pressure difference. When the second disk 2 is not rotating, the zero flow pressure difference is at the origin of the figure; in other words, if there is no flow, no pressure difference occurs. This is because, as the second disk 2 rotates, the zero flow pressure difference shifts upward as the rotation speed of the second disk 2 increases. This is because a centrifugal pressure difference is generated as long as there is peripheral velocity.

[0023] In the structure shown in Figure 2, the upstream end of the external fluid is connected to the inner circumferential end face I of the gap passage, and the downstream end of the external fluid is connected to the outer circumferential end face O of the gap passage (i.e., as shown in Figure 5). The fluid flows in from the inner circumferential end face of the gap passage and flows out from the outer circumferential end face of the gap passage. Viscous frictional resistance is directed inward along the radial direction, and centrifugal inertia force is directed outward along the radial direction. Therefore, the pressure difference in the gap passage (in this example, the pressure at the inner circumferential end face of the gap passage minus the pressure at the outer circumferential end face) is the viscous pressure difference minus the centrifugal pressure difference. Figure 6 compares the flow resistance characteristic curves for two cases: when the second disk 2 is rotating and when it is not. Since the viscous pressure difference and the centrifugal pressure difference are in a subtractive relationship, the flow resistance characteristic curve shifts downward as the second disk 2 rotates. The faster the rotation speed of the second disk 2, the faster the peripheral velocity of the fluid, and the greater the degree of downward shift of the flow resistance characteristic curve.

[0024] Conventional variable viscous flow resistance structures, as shown in Figure 1, change the flow resistance characteristic curve by changing the fluid or structural characteristic variables, and in all cases, the characteristic curve passes through the origin of zero pressure difference and zero flow rate. The variable viscous flow resistance structure of this embodiment, as shown in Figures 4 and 6, can generate zero flow rate pressure difference by shifting the flow resistance characteristic curve upward or downward. This is a significant technological innovation of the present invention.

[0025] Example 2 Figure 7 shows a specific structure designed based on Embodiment 1. This viscous flow resistance structure includes a housing 6, a disk 7, and a motor 8. The housing 6 has a first housing opening 9 and a second housing opening 10. A disk 7 is provided inside the housing 6, and a gap passage 3 is formed between the upper surface of the disk 7 and the inner surface S of the housing. The motor 8 is mounted on the housing 6, and the motor shaft is connected to and fixed to the disk. The motor rotates the disk. A seal ring 11 is provided between the motor shaft and the housing to prevent fluid leakage. The upstream end of the external fluid is connected to the outer circumferential end face of the gap passage via the first housing opening, and the downstream end is connected to the inner circumferential end face of the gap passage via the second housing opening. The external fluid flows into the housing from the first housing opening, then flows into the gap passage from the outer circumferential end face of the gap passage, flows out of the gap from the inner circumferential end face of the gap passage, and flows out of the housing from the second housing opening. The motor rotates the disk, and at this time, the flow resistance characteristic curve changes as shown in Figure 4.

[0026] When fluid flows in through the second housing opening and out through the first housing opening, a flow is formed in the gap passage from the inner end face to the outer end face. The pressure difference is the difference between the pressure at the inner end face (upstream pressure) and the pressure at the outer end face (downstream pressure). At this time, the flow resistance characteristic curve changes as shown in Figure 6.

[0027] Example 3 In Examples 1 and 2, one side of the gap passage rotates while the other side remains stationary. According to the principles of fluid dynamics, the fluid near the rotating surface maintains the same velocity as the rotating surface, while the fluid near the stationary surface remains stationary. Therefore, within the gap passage, the circumferential velocity (abbreviated as circumferential speed) of the fluid becomes non-uniform in the direction perpendicular to the disk, meaning that the fluid within the gap passage does not rotate sufficiently.

[0028] This embodiment proposes a solution as shown in Figure 8. The center of the first disk 1 is provided with a plurality of communication holes 4 (shown by dashed lines in the figure). The inner circumferential end surface I of the gap passage 3 communicates with the external fluid through the communication holes. Both disks rotate at the same speed. Since both the upper and lower surfaces of the gap passage are rotating surfaces, the fluid is completely rotationally driven, and the peripheral velocity of the fluid becomes closer to a uniform distribution in the direction perpendicular to the disk.

[0029] The fluid in the gap passage is driven by both the upper and lower surfaces, resulting in more sufficient fluid rotation. Under the same disk rotation speed conditions, the degree of shift in the flow resistance characteristic curve is greater when both the upper and lower surfaces rotate than when only one surface rotates. Figure 9 shows the case where the external fluid flows in from the outer circumferential end face of the gap and flows out from the inner circumferential end face, while Figure 10 shows the case where the external fluid flows in from the inner circumferential end face and flows out from the outer circumferential end face. In the figures, line a represents the case of no rotation, a' represents the case where one surface rotates, and a'' represents the case where both surfaces rotate.

[0030] Example 4 Figure 11 shows a specific structure designed based on Embodiment 3. Two disks are fixed together by a plurality of spacers 12 having a certain thickness, and a gap passage 3 is formed between the two disks. The two disks are mounted inside a housing 6. A motor 8 is fixed to the housing 6, and its shaft passes through the housing 6 and is connected to the second disk 2, which rotates the two disks. A communication hole 4 is provided in the center of the first disk 1. The housing is provided with a first housing opening 9 and a second housing opening 10. The first housing opening 9 connects the outer peripheral end face of the gap passage to the external fluid, and the communication hole 4 connects the inner peripheral end face of the gap passage to the external fluid via the second housing opening 10. A seal ring 11 is provided between the first disk 1, the motor shaft and the housing to prevent fluid leakage. The external fluid flows in through the second housing opening 10 and the communication hole 4 and flows out through the first housing opening, as shown in Figure 11. External fluid can flow in through the first housing opening and out through the communication hole 4 and the second housing opening 10.

[0031] Example 5 This embodiment is a further improvement on Embodiment 4. In this embodiment, a switching valve 14 is provided to switch the direction of flow within the gap passage by switching the connection configuration between the upstream and downstream of the external fluid and both end faces (inner and outer circumferential end faces) of the gap passage. The switching valve 14 in Figure 12 has four ports A, B, C, and D. Of these, port A is connected to the upstream of the external fluid, port B is connected to the downstream of the external fluid, port C is connected to the second housing opening 10, and port D is connected to the first housing opening 9. When the switching valve 14 connects port A and port C, and port B and port D, the external fluid flows in from the inner circumferential end face of the gap passage and flows out from the outer circumferential end face. By setting the rotation speed, the flow resistance characteristic curve can be shifted downward. When the switching valve 14 connects port A and port D, and port B and port C, the external fluid flows in from the outer circumferential end face of the gap passage and flows out from the inner circumferential end face. By setting the rotational speed, the flow resistance characteristic curve can be shifted upward. As shown in Figure 13, the pressure difference in the figure is the upstream pressure of the external fluid minus the downstream pressure.

[0032] Example 6 In the previously described embodiment, there is only one gap passage. In this embodiment, as shown in Figure 14, a multilayer gap passage structure is employed. This viscous flow resistance structure includes a first disk 1, a second disk 2, a third disk 15, and a fourth disk 16, with multiple spacers 12 of a certain thickness provided between the four disks, forming three gap passages 3. Communication holes 4 are provided in the centers of the first disk 1, the second disk 2, and the third disk 15. The inner circumferential end faces of the three gap passages communicate with each other via the communication holes 4 and communicate with the external fluid.

[0033] We will compare the case with one gap passage with the case with three gap passages. Let h be the spacer height of the one gap passage, and h' be the spacer height of each of the three gap passages. We will explain using the example where the fluid flows in from the outer end face of the gap passage and flows out from the inner end face.

[0034] (1) Figure 15 shows a comparison of the flow resistance characteristic curves when h=h'. For the same pressure difference, the flow rate in the three gap passages is three times that of the flow rate in one gap passage. If the rotational speed is the same, the degree of upward movement of the flow resistance characteristic curve is the same, that is, the zero flow rate pressure difference is the same.

[0035] (2) By adjusting h', the flow resistance characteristic curve for the case of three gap passages and the flow resistance characteristic curve for the case of one gap passage are superimposed in the case of no rotation. Clearly, h' is smaller than h. At the same rotational speed, the degree of upward movement in the case of three gap passages is greater than in the case of one gap passage. This is because in the case of three gap passages there are six surfaces of rotation for driving the fluid to rotate, and the gap spacing h' is smaller, improving the rotational driving effect, bringing the peripheral velocity of the fluid closer to the peripheral velocity of the disk, resulting in more sufficient rotation, and thereby increasing the centrifugal inertia and centrifugal pressure difference.

[0036] Example 7 This embodiment utilizes the above-described variable viscous flow resistance structure to measure flow rate. First, the principle and problems of using a viscous flow resistance structure for flow rate measurement will be explained. A common method for detecting flow rate is to utilize viscous flow structures. Typical viscous flow resistance structures include narrow tubes and gaps. Based on the flow resistance characteristic curve of the viscous flow resistance structure, a pressure difference sensor measures the pressure difference, and then the flow rate can be calculated from the relationship between that pressure difference and the flow rate. This is the principle of measuring flow rate using viscous flow resistance structures. The disadvantages of conventional viscous flow meters are as follows:

[0037] (1) Since the range of the pressure difference sensor is constant, the range of the flow meter is also constant. As shown in Figure 17, the maximum measurable flow rate is determined by the maximum measurable pressure of the pressure difference sensor. If it is necessary to widen the flow rate measurement range, it is necessary to use a pressure difference sensor with a wider range.

[0038] (2) When measuring minute flow rates, the measurement accuracy of the pressure difference sensor is very low, and therefore the measurement accuracy of minute flow rates is also very low. For example, the range of the pressure difference sensor is 0 to 100 Pa, and its deviation is 5% of the full range (usually stated as 5% FS), i.e., ±5 Pa. When measuring a pressure difference of 90 Pa using this sensor, the measurement accuracy is ±5 Pa / 90 Pa, and when measuring a pressure difference of 10 Pa using this sensor, the measurement accuracy is ±5 Pa / 10 Pa. Clearly, the smaller the pressure difference, the worse the flow rate measurement accuracy becomes. Furthermore, pressure difference sensors also have serious nonlinearity and dead zone problems near the zero point (i.e., they cannot detect changes in pressure difference in a small pressure difference range), and as a result, measuring minute flow rates becomes very difficult.

[0039] This embodiment solves the above-mentioned problems of flow measurement using the variable viscosity flow resistance structure of the present invention. Figure 18a shows a flow meter including a housing 6, a disk 7, and a motor 8, the housing 6 having a first housing opening 9 and a second housing opening 10. The disk 7 is provided inside the housing, and a gap passage is formed between the disk and the inner surface of the housing. The motor 8 is mounted on the housing and rotates the disk 7. The external fluid is connected upstream to the first housing opening 9 and downstream to the second housing opening 10. The external fluid flows into the housing from the first housing opening 9, then into the gap from the outer peripheral port of the gap passage, and finally out of the gap from the inner peripheral port of the gap passage, and flows to the external fluid from the second housing opening 10. A pressure difference sensor 13 is provided to measure the pressure difference at two different radial positions in the gap passage. The two different radial positions may be the inner and outer peripheral end faces of the gap passage, respectively. As shown in Figure 18b, the pressure difference sensor connects the inner and outer peripheral end faces of the gap passage.

[0040] As shown in Figure 19, the flow resistance characteristic curve when the disk 7 is not rotating and the flow resistance characteristic curve when the disk 7 is rotating at a constant speed are obtained by calibration experiments. When measuring minute flow rates, the disk 7 rotates at a constant speed, which can generate a large pressure difference even with minute flow rates. This avoids the low accuracy, nonlinearity, and dead zone of the pressure difference sensor in the range of small pressure differences, and effectively improves the detection accuracy of minute flow rates.

[0041] By changing the fluid flow direction in Figure 18 so that fluid flows in from the inner end face of the gap passage and out from the outer end face, the flow rate measurement range can be expanded. The flow resistance characteristic curve when the disk is not rotating and the flow resistance characteristic curve when the disk is rotating at a constant rotational speed are obtained by calibration experiments. As shown in Figure 20, when the disk 7 is not rotating, the maximum measurable pressure difference of the pressure difference sensor corresponds to the maximum measurable flow rate A, and when the disk 7 is rotating, the maximum measurable pressure difference of the pressure difference sensor corresponds to the maximum measurable flow rate B. If the flow rate is less than the maximum measurable flow rate A, the flow rate can be estimated using the flow resistance characteristic curve when the disk is not rotating. If the flow rate is greater than the maximum measurable flow rate A, the flow rate can be estimated using the flow resistance characteristic curve when the disk is rotating. Therefore, the flow rate measurement range can be expanded from flow rate A to flow rate B.

[0042] Furthermore, by combining the switching valve of this embodiment with that of Embodiment 5, and switching the connection between the upstream and downstream of the external fluid and the inner and outer circumferential end faces of the gap passage, it is possible to improve the measurement accuracy of minute flow rates and broaden the measurement range.

[0043] In this invention, the flow resistance characteristic curve is represented as a straight line to show the trend of change in the flow resistance characteristic curve. However, the actual curve may not be a straight line, but this does not affect the solution or inventiveness of the present invention.

[0044] The foregoing are merely some embodiments of the present invention and do not limit it. All modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should all be included within the scope of protection of the present invention. [Explanation of symbols]

[0045] 1. Disc 1 2. Second Disc 3. Gap passage 4 Communication hole 5. Rotation axis 6 Housing 7 discs 8 motors 9. First housing opening 10. Second housing opening 11 Seal ring 12 Spacers 13. Pressure difference sensor 14. Switching valve 15. Disc 3 16. Disc 4 Outer end face of O gap I. Inner end face of the gap Interior of S Housing

Claims

1. A variable viscous flow resistance mechanism comprising two or more surface members rotated by a rotational driving means, wherein one or more gap passages are formed between different surface members, an external fluid flows through the gap passage, at least one of the upper and lower surface members of the gap passage rotates continuously, and the pressure difference generated radially in the gap passage by the centrifugal inertia of the fluid due to the rotation is superimposed on the viscous pressure difference within the gap passage, causing a change in the flow resistance characteristic curve.

2. The variable viscosity flow resistance mechanism according to claim 1, characterized in that the external fluid flows in from the inner circumferential end face of the gap passage and flows out from the outer circumferential end face.

3. The variable viscosity flow resistance mechanism according to claim 1, characterized in that the external fluid flows in from the outer peripheral end face of the gap passage and flows out from the inner peripheral end face.

4. The variable viscous flow resistance mechanism according to claim 1, characterized in that the upper and lower surfaces of the gap passage are connected by a spacer and rotate as a single unit.

5. The variable viscous flow resistance mechanism according to claim 1, characterized in that a plurality of gap passages are formed in the viscous flow resistance mechanism, and the outer circumferential end faces of the plurality of gap passages are in communication with each other, and the inner circumferential end faces are also in communication with each other.

6. The variable viscous flow resistance mechanism according to claim 1, further comprising at least one switching valve, the switching valve being connected to the inner and outer circumferential end faces of the gap passage and to either the upstream or downstream of the external fluid, and the switching valve changing the flow direction within the gap passage by switching the connection state between the upstream and downstream of the external fluid and the inner and outer circumferential end faces of the gap passage.

7. The variable viscous flow resistance mechanism according to claim 1, further comprising at least one pressure difference sensor for measuring the pressure difference at two different radial positions within a gap passage.

8. A variable viscous flow resistance mechanism comprising a housing, a motor, and at least one disk, wherein the housing has a first housing opening and a second housing opening, the disk is provided within the housing, a gap passage is formed between the upper surface of the disk and the inner surface of the housing, the motor is mounted on the housing, the motor shaft is connected to and fixed to the disk and continuously rotates the disk, and the upstream or downstream of an external fluid is connected to the outer circumferential end face of the gap passage via the first housing opening, and the corresponding downstream or upstream is connected to the inner circumferential end face of the gap passage via the second housing opening.

9. A variable viscosity flow resistance mechanism comprising a housing, a motor, and at least two disks, wherein the housing has a first housing opening and a second housing opening, the disks are provided within the housing and the disks are integrally fixed together by spacers, thereby forming a gap passage between the disks, the shaft of the motor passes through the housing and is connected to the disks, and continuously rotates the disks, the upstream or downstream of an external fluid is connected to the outer circumferential end face of the gap passage via the first housing opening, and the corresponding downstream or upstream is connected to the inner circumferential end face of the gap passage via the second housing opening.

10. A flow sensor characterized by including a variable viscosity flow resistance mechanism as described in any one of claims 1 to 9.

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