Variable viscous flow resistance structure

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 technology]

[0002] When a fluid passes through a solid wall, the fluid has viscosity, so viscous friction will occur between the fluid and the solid wall. A structure that generates viscous friction is called a viscous flow resistance structure. Viscous flow resistance structures and their viscous friction are important factors that affect the movement of fluids. Common viscous flow resistance structures include pipelines, porous materials, narrow gaps, etc. In practical applications, viscous flow resistance structures often play a negative role. For example, during the transportation of tap water, oil, and natural gas, the viscous friction of the pipeline will cause large pressure losses and energy dissipation along the way. However, viscous flow resistance structures also have some positive applications. For example, the invention patent with application number CN202210083296.2 processes a rectangular channel in a cylindrical body to build a narrow gap, and then uses the linear relationship between the flow rate and pressure difference of the narrow gap to measure the flow rate.

[0003] The relationship curve between the flow rate and pressure difference (the pressure difference is the pressure on the upstream side of the fluid flow minus the pressure on the downstream side), that is, the flow resistance characteristic curve, depends on the inherent characteristic variables, such as the magnitude of the flow resistance, the viscosity, density, etc. of the fluid. Usually, the method of changing the flow resistance characteristic curve is to change these inherent characteristic variables. The invention patent with application number CN202210083296.2 can change the height of the gap passage by changing the width of the rectangular channel, thereby changing the flow resistance when the fluid flows through the gap passage. As shown in FIG. 1, when the gap height increases, the flow resistance characteristic curve deflects downward, and when the gap height decreases, the flow resistance characteristic curve deflects upward. In addition, as another example, CN103807502A proposes another method of changing the flow resistance characteristic curve. When the fluid flows through the porous material, the present invention changes the temperature of the fluid by heating the porous material, changing the viscosity and density of the fluid, thereby achieving the purpose of changing the flow resistance characteristic curve.

[0004] The present invention proposes a new viscous flow resistance structure that realizes a change in the flow resistance characteristic curve by superimposing the rotational inertia of the fluid, without the need to change the inherent characteristic variables of the fluid or the flow resistance structure. Summary of the Invention [Problem to be solved by the invention]

[0005] Considering the drawbacks of the prior art, the object of the present invention is to propose a variable viscosity flow resistance structure, which changes its flow resistance characteristics by superimposing a rotation, without the need to change the inherent characteristic attributes of the fluid or the structure. [Means for solving the problem]

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A variable viscosity flow resistance structure includes two or more surfaces, one or more gap passages are formed between the different surfaces, 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 flow in from an inner peripheral end surface of the gap passage and flow out from an outer peripheral end surface of the gap passage.

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

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

[0011] Furthermore, in the viscous flow resistance structure, a plurality of gap passages are formed, and the outer peripheral end faces of the plurality of gap passages communicate with one another, and the inner peripheral end faces also communicate with one another.

[0012] Furthermore, the viscous flow resistance structure further includes at least one switching valve, which is connected to both the inner and outer end faces of the gap passage and the upstream and downstream sides of the external fluid, and which switches the connection state between the upstream and downstream of the external fluid and the inner and outer end faces of the gap passage to change the flow direction in the gap passage.

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

[0014] A variable viscosity flow resistance structure includes a housing, a motor, and at least one disk, the housing having a first housing opening and a second housing opening, the disk being disposed within the housing, a gap passage being formed between an upper surface of the disk and an inner surface of the housing, the motor being attached to the housing, the motor shaft being connected and fixed to the disk to rotate and drive the disk, and the upstream or downstream of an external fluid being connected to an outer peripheral end surface of the gap passage via the first housing opening, and the corresponding downstream or upstream being connected to an inner peripheral end surface of the gap passage via the second housing opening.

[0015] A variable viscosity flow resistance structure includes a housing, a motor, and at least two disks, the housing having a first housing opening and a second housing opening, the disks are disposed within the housing, and the disks are fixed together by a spacer to form a gap passage between the disks, a shaft of the motor passes through the housing and is connected to the disks to rotate the disks, and an upstream or downstream of an external fluid is connected to an outer peripheral end face of the gap passage via the first housing opening, and a corresponding downstream or upstream is connected to an inner peripheral end face of the gap passage via the second housing opening.

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

[0017] By adopting the structure of the present invention, it is possible to achieve adjustment to viscous fluid resistance without changing the inherent characteristics of the fluid or the inherent characteristics of the structure, and the overall structural components are few and easy to process, making it highly applicable in fields such as flow measurement. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a flow resistance characteristic curve of a gap passage, in which line a' indicates a decrease in gap height relative to line a, and line a'' indicates an increase in gap height relative to line a. [Diagram 2] FIG. 2 is a schematic diagram of the principle of a specific viscous flow resistance structure of the present invention. [Diagram 3] FIG. 3 is a schematic diagram of an example of a fluid flow in the structure of FIG. 2, in which the fluid flows in from an outer peripheral end face of a gap passage and flows out from an inner peripheral end face of the gap passage. [Figure 4] FIG. 4 is a schematic diagram of flow resistance characteristic curves in two cases, when the second disk in the example of FIG. 3 is rotating and when it is not rotating, where line a is the case when it is not rotating and line a' is the case when it is rotating. [Diagram 5] FIG. 3 is a schematic diagram showing an example of a fluid flow in the structure of FIG. 2, in which the fluid flows in from an inner peripheral end face of a gap passage and flows out from an outer peripheral end face of the gap passage. [Figure 6] FIG. 6 is a schematic diagram of flow resistance characteristic curves in two cases, when the second disk in the example of FIG. 5 is rotating and when it is not rotating, and in the figure, line a is the case when it is not rotating and line a' is the case when it is rotating. [Figure 7] FIG. 2 is a schematic diagram of an apparatus for a particular viscous flow resistance structure of the present invention. [Figure 8] FIG. 2 is a schematic diagram of the principle of another specific viscous flow resistance structure of the present invention. [Figure 9] FIG. 8 is a schematic diagram of flow resistance characteristic curves in various cases for the structure. 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 when there is no rotation, line a' is the case when one face rotates, and line a'' is the case when two faces rotate. [Figure 10] FIG. 8 is a schematic diagram of flow resistance characteristic curves in various cases for the structure. The external fluid flows in from the inner end face of the gap and flows out from the outer end face. In the figure, line a is the case when there is no rotation, line a' is the case when one face rotates, and line a'' is the case when two faces rotate. [Figure 11] FIG. 2 is a schematic diagram of an apparatus for another viscous flow resistance structure of the present invention. [Figure 12] FIG. 2 is a schematic diagram of an apparatus for yet another specific viscous flow resistance structure of the present invention. [Figure 13]FIG. 13 is a schematic diagram of flow resistance characteristic curves for various cases in the example of FIG. 12. In the diagram, line a is the case of non-rotation, line a' is the situation in which switching valves A and D and B and C are connected, and line a'' is the situation in which switching valves A and C and B and D are connected. [Figure 14] FIG. 2 is a schematic diagram of the principle of yet another specific viscous flow resistance structure of the present invention, in which there are multiple gap passages. [Figure 15] This is a comparison of schematic diagrams of flow resistance characteristic curves when h = h' in the structure of Figure 14. In the figure, line a is the case of non-rotation when there is only one gap passage, line 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 line b' is the case of rotation when there are three gap passages. [Figure 16] This is a comparison of schematic diagrams of flow resistance characteristic curves when h>h' in the structure of Figure 14. In the figure, line a is the case of non-rotation when there is only one gap passage, line 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 line b' is the case of rotation when there are three gap passages. [Figure 17] FIG. 1 is a schematic diagram of the range of flow measurement using pressure difference of a viscous flow resistance structure. [Figure 18a] FIG. 2 is a structural schematic diagram of a flowmeter according to the present invention. [Figure 18b] FIG. 4 is a structural schematic diagram of another flow meter of the present invention. [Figure 19] FIG. 18B is a schematic diagram of flow resistance characteristic curves for various cases in the example of FIG. 18a or FIG. 18b, where 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 diagram, line a is the case where the disk is not rotating, and line a' is the case where the disk rotates at a constant rotation speed. [Figure 20] 18a or 18b, 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 where the two disks rotate at the same constant rotation speed, and line a' is the case where the two disks rotate at the same constant rotation speed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0020] Example 1 FIG. 2 is a schematic diagram of the viscous flow resistance structure. The viscous flow resistance structure is composed 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 in the center of the first disk 1, which communicates the inner peripheral end face of the gap passage with 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 from one end face of the gap passage 3 and flows out from the other end face of the gap passage. The flow of the fluid is subjected to viscous friction resistance at the upper and lower faces of the gap passage. Furthermore, the fluid is driven by the second disk 2, and a circumferential velocity is generated. Figure 3 shows one specific example of the flow. The upstream of the external fluid is connected to the outer peripheral end face O of the gap passage, and the downstream of the external fluid is connected to the inner peripheral end face I of the gap passage. Therefore, the fluid flows in from the outer peripheral end face of the gap passage and flows out from the inner peripheral end face. The fluid forms a fluid flow from the outer periphery to the inner periphery in the gap passage. The flow of the fluid is mainly subjected to the following two forces. One is the viscous friction resistance at the upper and lower faces of the gap passage, and the viscous friction force generates a pressure difference (hereinafter abbreviated as viscous pressure) in the radial direction of the gap passage. The other is the centrifugal inertia force generated by the circumferential velocity, and the centrifugal inertia force generates a pressure difference (hereinafter abbreviated as centrifugal pressure difference) in the radial direction of the gap passage. The centrifugal inertia force and the viscous friction resistance have the same direction (outward along the radial direction), and the viscous pressure difference and the centrifugal pressure difference are in a superimposed relationship. Therefore, the pressure difference in the gap passage is the viscous pressure difference plus the centrifugal pressure difference. In the present invention, the pressure difference in the gap passage refers to the pressure at the end face where the fluid flows in minus the pressure at the end face where the fluid flows out. For example, in FIG. 3, the pressure difference in the gap passage is the pressure at the outer peripheral end face minus the pressure at the inner peripheral end face.

[0022] Figure 4 compares the flow resistance characteristic curves in the two cases of the second disk 2 rotating and not rotating in the example of Figure 3. Because the centrifugal pressure difference is superimposed, the rotation of the second disk 2 causes the flow resistance characteristic curve to move upward, and the faster the rotation speed of the second disk 2, the faster the circumferential speed of the fluid becomes, and the greater the degree of upward movement 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, that is, if there is no flow, no pressure difference occurs. This is because when the second disk 2 rotates, the zero flow pressure difference moves upward as the rotation speed of the second disk 2 increases. This is because as long as there is a circumferential speed, a centrifugal pressure difference occurs.

[0023] In the structure shown in FIG. 2, when the upstream of the external fluid is connected to the inner peripheral end face I of the gap passage, the downstream of the external fluid is connected to the outer peripheral end face O of the gap passage (that is, as shown in FIG. 5). 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. The viscous friction resistance is directed inward along the radial direction, and the 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 peripheral end face of the gap passage minus the pressure at the outer peripheral end face) is the viscous pressure difference minus the centrifugal pressure difference. FIG. 6 compares the flow resistance characteristic curves in two cases, that is, when the second disk 2 rotates and when it does not rotate. Since the viscous pressure difference and the centrifugal pressure difference are in a subtractive relationship, the rotation of the second disk 2 causes the flow resistance characteristic curve to move downward. The faster the rotation speed of the second disk 2, the faster the circumferential speed of the fluid becomes, and the greater the degree of downward movement of the flow resistance characteristic curve becomes.

[0024] The variable viscosity flow resistance structure of the prior art changes the flow resistance characteristic curve by changing the characteristic variables of the fluid or structure, and the characteristic curves all pass through the origin of zero pressure difference and zero flow rate, as shown in Figure 1. The variable viscosity flow resistance structure of the present embodiment can shift the flow resistance characteristic curve up or down to produce a zero flow rate pressure difference, as shown in Figures 4 and 6. This is a key technical innovation of the present invention.

[0025] Example 2 FIG. 7 is a specific structure designed based on Example 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 in 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 attached to the housing 6, and the motor shaft is connected and fixed to the disk. The motor drives the disk to rotate. A seal ring 11 is provided between the motor shaft and the housing to prevent fluid leakage. The upstream of the external fluid is connected to the outer peripheral end surface of the gap passage through the first housing opening, and the downstream is connected to the inner peripheral end surface of the gap passage through 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 peripheral end surface of the gap passage, flows out of the gap from the inner peripheral end surface of the gap passage, and flows out of the housing from the second housing opening. The motor drives the disk to rotate, and at this time, the flow resistance characteristic curve changes as shown in FIG. 4.

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

[0027] Example 3 In the first and second embodiments, one surface of the gap passage rotates and the other surface is stationary. According to the knowledge of fluid mechanics, the fluid close to the rotating surface maintains the same velocity as the rotating surface, and the fluid close to the stationary surface remains stationary. Therefore, in the gap passage, the circumferential velocity of the fluid (abbreviated as circumferential speed) becomes non-uniform in the direction perpendicular to the disk, which means that the fluid in the gap passage does not rotate sufficiently.

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

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

[0030] Example 4 FIG. 11 is a specific structure designed based on Example 3. The two disks are fixed together by a number of spacers 12 having a certain thickness, and a gap passage 3 is formed between the two disks. The two disks are mounted in 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 to rotate 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 communicates the outer peripheral end face of the gap passage with the external fluid, and the communication hole 4 communicates the inner peripheral end face of the gap passage with the external fluid through the second housing opening 10. A seal ring 11 is provided between the first disk 1, the motor shaft, and the housing to prevent leakage of fluid. 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 FIG. 11. An external fluid can flow in through the first housing opening and flow out through the communication hole 4 and the second housing opening 10 .

[0031] Example 5 This embodiment is a further improvement of the fourth embodiment. In this embodiment, a switching valve 14 is provided to switch the connection between the upstream and downstream of the external fluid and both end faces (the inner peripheral end face and the outer peripheral end face) of the gap passage to switch the flow direction in the gap passage. The switching valve 14 in FIG. 12 has four ports A, B, C, and D. Among them, 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 communicates port A with port C and port B with port D, the external fluid flows in from the inner peripheral end face of the gap passage and flows out from the outer peripheral end face. By setting the rotation speed, the flow resistance characteristic curve can be shifted downward. When the switching valve 14 communicates port A with port D and port B with port C, the external fluid flows in from the outer peripheral end face of the gap passage and flows out from the inner peripheral end face. By setting the rotation 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 above-mentioned embodiment, there is only one gap passage. In this embodiment, as shown in FIG. 14, a multi-layer gap passage structure is adopted. This viscous flow resistance structure includes a first disk 1, a second disk 2, a third disk 15, and a fourth disk 16, and a plurality of spacers 12 of a certain thickness are provided between the four disks, and three gap passages 3 are formed. A communication hole 4 is provided in the center of the first disk 1, the second disk 2, and the third disk 15. The inner peripheral end faces of the three gap passages communicate with each other through the communication hole 4 and also communicate with the external fluid.

[0033] The case with one gap passage will be compared with the case with three gap passages. The spacer height of one gap passage is h, and the spacer height of each of the three gap passages is h'. An example will be explained in which the fluid flows in from the outer peripheral end face of the gap passage and flows out from the inner peripheral end face.

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

[0035] (2)By adjusting h', in the non-rotating case, the flow resistance characteristic curve in the case of three gap passages is superimposed on the flow resistance characteristic curve in the case of one gap passage. Obviously, h' is smaller than h. For the same rotation speed, the degree of upward movement in the case of three gap passages is larger than that in the case of one gap passage. This is because in the case of three gap passages, there are six rotating surfaces to rotate and drive the fluid, and the gap interval h' is smaller, the rotation driving effect is improved, the circumferential speed of the fluid is closer to the circumferential speed of the disk, and the rotation is more sufficient, which leads to a larger centrifugal inertia effect and centrifugal pressure difference.

[0036] Example 7 In this embodiment, the flow rate is measured by utilizing the variable viscous flow resistance structure. First, the principle and problems of using the viscous flow resistance structure for flow rate measurement will be described. It is a common method to detect flow rate by using viscous flow structure. Common viscous flow resistances include thin tubes, gaps, etc. Based on the flow resistance characteristic curve of the viscous flow resistance structure, the pressure difference can be measured by a pressure difference sensor, and then the flow rate can be calculated from the relationship between the pressure difference and the flow rate. This is the principle of measuring flow rate by using viscous flow resistance structure. The disadvantages of conventional viscous flowmeters are as follows:

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

[0038] (2) In the case of measuring minute flow rates, the measurement accuracy of the pressure difference sensor is very low, so the measurement accuracy of the minute flow rate is also very low. For example, the range of a pressure difference sensor is 0 to 100 Pa, and its deviation is 5% of the full range (usually written as 5%FS), that is, ±5 Pa. If this sensor is used to measure a pressure difference of 90 Pa, its measurement accuracy is ±5 Pa / 90 Pa, and if this sensor is used to measure a pressure difference of 10 Pa, its measurement accuracy is ±5 Pa / 10 Pa. Obviously, the smaller the pressure difference, the worse the flow rate measurement accuracy. In addition, the pressure difference sensor also has serious nonlinearity and dead zone problems near the zero point (i.e., it cannot detect changes in pressure difference in a small pressure difference range), which makes it very difficult to measure minute flow rates.

[0039] This embodiment uses the variable viscosity flow resistance structure of the present invention to solve the above problems of flow measurement. Figure 18a is a flowmeter including a housing 6, a disk 7, and a motor 8, in which a first housing opening 9 and a second housing opening 10 are opened in the housing 6. A disk 7 is provided inside the housing, and a gap passage is formed between the disk and the housing inner surface. The motor 8 is attached to the housing and drives the disk 7 to rotate. An external fluid is connected to the first housing opening 9 at the upstream side and to the second housing opening 10 at the downstream side. The external fluid flows into the housing from the first housing opening 9, then flows into the gap from the outer peripheral port of the gap passage, and finally flows out of the gap from the inner peripheral port of the gap passage, and flows into 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 peripheral end surface and the outer peripheral end surface of the gap passage, respectively. As shown in Figure 18b, the pressure difference sensor connects the inner peripheral end surface and the outer peripheral end surface of the gap passage.

[0040] As shown in Fig. 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 rotation speed are obtained by calibration experiments. When measuring minute flow rates, the disk 7 rotates at a constant rotation speed, so that a large pressure difference can be generated even at a minute flow rate, thereby avoiding the low accuracy, nonlinearity and dead zone of the pressure difference sensor in the range of small pressure differences, and effectively improving the detection accuracy of minute flow rates.

[0041] If the flow direction of the fluid in FIG. 18 is changed so that it flows in from the inner peripheral end face of the gap passage and flows out from the outer peripheral end face, the flow measurement range can be expanded. A flow resistance characteristic curve when the disk is not rotating and a flow resistance characteristic curve when the disk is rotating at a constant rotation speed are obtained by a calibration experiment. As shown in FIG. 20, when the disk 7 is not rotating, the maximum measured pressure difference of the pressure difference sensor corresponds to the maximum measured flow rate A, and when the disk 7 is rotating, the maximum measured pressure difference of the pressure difference sensor corresponds to the maximum measured flow rate B. When the flow rate is less than the maximum measured flow rate A, the flow resistance characteristic curve when the disk is not rotating can be used to estimate the flow rate. When the flow rate is greater than the maximum measured flow rate A, the flow resistance characteristic curve when the disk is rotating can be used to estimate the flow rate. Thus, the flow measurement range can be expanded from flow rate A to flow rate B.

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

[0043] In the present invention, the flow resistance characteristic curve is represented by a straight line to show the change trend of the flow resistance characteristic curve, but the actual curve may not be a straight line, but this does not affect the solution and inventive step of the present invention.

[0044] The above are only some embodiments of the present invention, and are not intended to limit the present invention. All modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention. [Explanation of symbols]

[0045] 1 Disc 1 2 Disc 2 3 Gap Passage 4 Communication hole 5 Rotation Axis 6. Housing 7 Disc 8 Motor 9 First housing opening 10 Second housing opening 11 Seal ring 12 Spacer 13 Pressure Difference Sensor 14 Switching valve 15 Third Disc 16 Fourth Disc O Outer periphery of gap I Inner circumference of gap S Housing inner surface

Claims

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

2. 2. The variable viscosity flow resistance structure according to claim 1, wherein the external fluid flows in from an inner peripheral end face of the gap passage and flows out from an outer peripheral end face of the gap passage.

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

4. 2. The variable viscosity flow resistance structure according to claim 1, wherein the upper and lower surfaces of the gap passage are connected by a spacer and rotate as a unit.

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

6. 2. The variable viscous flow resistance structure according to claim 1, further comprising at least one switching valve connected to both the inner and outer end faces of the gap passage and the upstream and downstream of the external fluid, and the switching valve switches the connection state between the upstream and downstream of the external fluid and the inner and outer end faces of the gap passage to change the flow direction in the gap passage.

7. 2. The variable viscous flow resistance structure of claim 1, further comprising at least one pressure differential sensor for measuring a pressure difference at two different radial positions in the gap passage.

8. A variable viscosity flow resistance structure comprising: a housing, a motor, and at least one disk, the housing having a first housing opening and a second housing opening, the disk being disposed within the housing, a gap passage being formed between an upper surface of the disk and an inner surface of the housing, the motor being attached to the housing, the motor shaft being connected and fixed to the disk to rotate and drive the disk, the upstream or downstream of an external fluid being connected to an outer peripheral end surface of the gap passage via the first housing opening, and the corresponding downstream or upstream being connected to an inner peripheral end surface of the gap passage via the second housing opening.

9. A variable viscosity flow resistance structure comprising: a housing, a motor, and at least two disks, the housing having a first housing opening and a second housing opening, the disks being disposed within the housing and fixed together by a spacer to form a gap passage between the disks, a shaft of a motor passing through the housing and connected to the disks to rotate the disks, an upstream or downstream of an external fluid being connected to an outer peripheral end face of the gap passage via the first housing opening, and a corresponding downstream or upstream being connected to an inner peripheral end face of the gap passage via the second housing opening.

10. A flow sensor comprising a variable viscosity flow resistance structure according to any one of claims 1 to 9.

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