JPH0136886B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the overall configuration of a flow rate detection device for measuring the flow rate of fluid.

Configuration of Conventional Example and its Problems Conventionally, this type of flow rate detection device is configured as shown in FIGS. 1 and 2. In FIGS. 1 and 2, reference numeral 1 denotes an annular flow path having a circular cross section, and an inflow path 2 and an outflow path 3 are opened at the outer periphery of this flow path. This inflow passage 2 is provided with a nozzle 4 . In addition, a sphere 5 is inserted into the annular flow path 1, transparent windows 6 and 7 are formed, and a light emitting element 8 is formed.
and a light receiving element 9 are provided. In such a configuration, when fluid enters the annular channel 1 from the nozzle 4 of the inflow channel 2, the flow flows from the inflow channel 2 to the outflow channel 3 while circulating in the annular channel 1, and the sphere 5 also flows along with it. It moves around inside the annular flow path 1 in the direction of the solid arrow. Since the rotational speed of the sphere is proportional to the flow rate of the fluid, the rotational speed of the sphere 5 is detected as a pulse signal by the light emitting element 8 and the light receiving element 9, and the flow rate is measured through the control circuit.
The problems with this conventional method include, first, that detection is impossible during long-term use or in opaque fluids. The light emitted from the light emitting element 8 passes through the transparent windows 6 and 7 and enters the light receiving element 9, and the sphere 5 intercepts this light to detect rotation. If water scale or scale adheres to the inside of channel 1, the amount of light passing through is reduced and becomes undetectable. Furthermore, since it is difficult for light to pass through opaque fluids, detection becomes impossible. The second reason is that the flow resistance is large. Since the annular flow path 1 is formed, the inlet and outlet of the flow path change direction, resulting in bending loss, and the circular flow intersects with the flow from the inflow path 2 near the inflow path, resulting in inflow resistance and loss. arise. Furthermore, if the sphere is configured to have a size close to the cross-sectional area of the annular flow path 1 so as to promote the rotation of the sphere 5, a large flow resistance will occur.
Further, if a nozzle 4 is provided in the inflow passage 2 so that the sphere 5 circulates smoothly, the flow passage resistance becomes even greater. Thirdly, there are problems with the structure, such as the sensor structure tends to be large. As mentioned above, the passage resistance increases, so it is necessary to increase the passage diameter to reduce it, and since it has an annular flow passage 1 compared to a straight pipe, more space is required. The sensor as a whole is larger than the front and rear passages. In addition, the directions of the inflow passage 2 and the outflow passage 3 are limited to some extent, which poses problems such as structural restrictions when incorporating the sensor into equipment, etc., and an increase in overall size.

Another conventional example is described in Japanese Patent Laid-Open No. 50-67674. However, in this conventional example, the fluid to be measured is introduced from the tangential direction of the vortex chamber to generate a swirling flow in the vortex chamber, and the rotating body made of a magnetic material is prevented from colliding with the inner wall of the vortex chamber. Since it is rotated and detected by a detection device (for example, one that detects changes in magnetic flux) provided on the outside, the flow path expands and contracts, resulting in a large pressure loss. In addition, the provision of a vortex chamber increases the size. Although the structure is such that the rotating body does not collide with the wall of the vortex chamber, the diameter and volume of the rotating body are constant, and the trajectory of the rotating body is not constant due to changes in centrifugal force due to changes in flow rate, resulting in problems such as unstable output signals. Ta.

Other conventional examples include JP-A-50-51758 and JP-A-52-113760. The former has a blade on the downstream side of the ball circulating in the flow path, so the ball rotates in the opposite direction when the flow is reversed, and there was a problem in that it outputs pulses during the reverse flow. On the other hand, the latter outputs pulses when an object moves between a Hall element and a magnet, but due to the positional relationship between the Hall element, magnet, and object, it is practically impossible to detect a sphere orbiting inside a pipe. I was faced with a difficult task.

Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional technology.The present invention has a small size, low pressure loss, and can be used even in the condition of scale adhesion in the flow path or in opaque fluids, and the output of the detection signal is stable. The purpose of this invention is to provide a flow rate detection device that is resistant to iron powder flowing through.

Structure of the Invention In order to achieve this object, the present invention includes a fixed vane that is provided in a pipe and generates a swirling flow by axially swirling the fluid to be detected, and a fixed vane that is located in the swirling flow and is perpendicular to the direction of the flow. A magnetic sphere that rotates in contact with the inner wall of the pipe in a direction, an outflow prevention means that keeps the magnetic sphere within the range of the swirling flow, and a rotation detection device that detects the number of revolutions of the magnetic sphere, and the rotation The detection device includes a magnetic detection element provided outside the pipe and at a position not in contact with the fluid to be detected within an extension of the circumferential surface around which the magnetic sphere revolves; A permanent magnet is installed at a position that is out of the extension of the circumferential surface of the fluid and does not come into contact with the fluid to be detected.With this configuration, even if iron powder or the like adheres to the inner wall of the flow path, the circumferential surface and the permanent magnet Because the positions of the two are shifted, a stable output signal can be obtained without being affected by iron powder. Further, by keeping the distance between the magnetic sphere and the magnetic detection element constant, stable detection signal output can be ensured.

DESCRIPTION OF EMBODIMENTS Next, embodiments of the present invention will be described based on FIGS. 3 and 4. Reference numeral 11 denotes a pipe such as a housing for forming a flow path 12. Fixed blades 13, which are swirling means for axially swirling the fluid to be detected, are provided inside the pipe 11, and are prevented from coming off by a ring 14. The central shaft 15, which is an outflow prevention means integrally constructed with the fixed blade 13, has a tapered surface 16 that expands the flow path and a tapered surface 17 that reduces the flow path in the flow direction. It has nearby. 18 is a magnetic sphere which is a magnetic rotating body, and the tapered surface 16 and the channel side wall 1 which is a circumferential surface
9 is provided in the upstream circumferential groove 20. Further, the tapered surface 17 and the channel side wall 19 constitute a downstream circumferential groove 21 . Note that tapered surface 1
7 prevents the magnetic sphere 18 from flowing out. A channel side wall 19 that is a circumferential surface around which the magnetic sphere 18 circulates.
Pipe 1 located nearby and not in contact with the fluid to be detected
1 includes a magnetoresistive element 22, which is a rotation detection device for the magnetic sphere 18, and a magnetoresistive element 22, which is a rotation detection device for the magnetic sphere 18.
A permanent magnet 23 that applies a magnetic field to the magnetic sphere 1
It is provided downstream from the position 8. 24,2
5 indicates the inlet and outlet of the pipe 11. 2
6 is an arrow indicating the flow direction. FIG. 5 is a diagram showing the fixed wing 13, and shows the central axis 15 and the outer frame 27.
A plurality of blade plates 28 are provided between them at a constant inclination. This fixed wing 13 is resin molded.
Possible types of the magnetic sphere 18 include a magnetic steel ball, a magnetic hollow steel ball, a resin ball molded with a magnetic steel ball, and a resin ball whose surface is magnetically plated. Further, as the permanent magnet 23, a rare earth magnet or a ferrite magnet is used, and as the magnetic detection element 22, a Hall element other than a magnetoresistive element is used.

Next, the operation of the above configuration will be explained with reference to FIGS. 3 and 4. The flow rate detection device is installed so that the inlet 24 and outlet 25 are in the vertical direction as shown in the figure. In such a state, when fluid flows into the pipe 11 from the direction of the arrow 26, the magnetic sphere 18 provided in the circumferential groove 20 moves towards the fixed blade 1.
3, the axially swirled swirling flow obtains a kinetic force and circulates in the flow path 12 in a direction perpendicular to the flow direction of the fluid. The number of rotations of the magnetic sphere 18 has a characteristic that it is proportional to the flow rate of the fluid. When the flow rate is low, the magnetic sphere 18 revolves around the circumferential groove 20, but when the flow rate is large, the magnetic sphere 18 circles around the circumferential groove 21, as shown in FIG.
To measure the flow rate, it is sufficient to measure the number of revolutions of the magnetic sphere 18 that circulates in proportion to the flow rate, and in this embodiment,
A permanent magnet 23 is provided on the outside of the pipe 11 located on the downstream side away from the extension of the circumferential surface of the magnetic sphere 18, and a magnetic resistance element 22 is provided on the outside of the pipe 11 at a position through which the magnetic field passes. The magnetic field from the permanent magnet 23 is configured to apply a magnetic field to the magnetic sphere 18 and the magnetic resistance element 22 when the magnetic sphere 18 approaches the magnetic resistance element 22. In such a positional relationship, when the magnetic sphere 18 passes by the magnetic resistance element 22 side, the direction of the magnetic field acting on the magnetic resistance element 22 from the permanent magnet 23 is bent in the direction of the magnetic sphere 18. . As a result, the strength of the magnetic field acting on the magnetoresistive element 22 changes, and the magnetoresistive element 22
The internal resistance of changes. This change in internal resistance is extracted as a change in voltage and output as a pulse signal. The flow rate can be measured by calculating and processing this pulse signal using a control circuit (not shown).

As described above, in this embodiment, the permanent magnet 2
3 is provided on the outside of the pipe 11 located on the downstream side of the magnetic sphere 18, so even if iron pieces, rust, etc. flowing through the flow path 12 are attached to the flow path side wall 19 due to the magnetic force of the permanent magnet 23, Since it is on the downstream side of the magnetic sphere 18, it does not affect the surroundings of the magnetic sphere 18, and stable orbiting operation can be obtained over a long period of time.

Furthermore, since the magnetic rotating body is composed of magnetic spheres, mechanical resistance and fluid resistance during rotation can be reduced compared to other shapes.

Effects of the Invention As is clear from the above description, the flow rate detection device of the present invention includes a fixed vane that is provided in a pipe and generates a swirling flow by axially swirling the fluid to be detected; a magnetic sphere that orbits in contact with the inner wall of the pipe in a direction perpendicular to the flow direction;
It consists of an outflow prevention means that keeps the magnetic sphere within the range of the swirling flow, and a rotation detection device that detects the number of revolutions of the magnetic sphere, and the rotation detection device is arranged outside the pipe and within the orbit of the magnetic sphere. A magnetic sensing element is provided at a position that is not in contact with the fluid to be detected within an extension of the surface, and a magnetic sensing element is provided at a position that is outside the pipe and is outside the extension of the circumferential surface of the magnetic sphere and is not in contact with the fluid to be detected. By providing a permanent magnet at a contact position, the following effects can be obtained.

(1) By removing the permanent magnet from the extension of the orbiting surface of the magnetic sphere, even if iron particles in the fluid adhere to the inner wall of the flow channel near the permanent magnet, it will not affect the orbiting of the magnetic sphere. It is possible to obtain stable orbiting motion and detect with high accuracy. Naturally, since it is a magnetic detection method, it is not affected by limescale or scale within the flow path.
It is also possible to measure opaque fluids.

(2) Regardless of the magnitude of the flow rate, the magnetic sphere orbits in contact with the side wall of the flow path, which is the circumferential surface, so when the magnetic sphere approaches the magnetic sensing element, the distance between the magnetic sphere and the magnetic sensing element is Always constant.
As a result, rotation can be detected using extremely stable output signals.

(3) Since the magnetic rotating body itself does not have a permanent magnet function, there is no drawback that iron particles in the flow path may adhere to the magnetic rotating body and adversely affect the rotation speed or durability. .

(4) Inside the flow path, the fixed blades that give swirling flow to the fluid have low resistance, and the magnetic spheres also rotate in the flow path against the axial flow, so their diameter is much smaller than the flow path diameter, and the overall flow rate is low. Resistance becomes extremely small.
Also, in comparison with conventional ball-type flow rate sensors, the flow resistance is extremely small, as there is no extreme bend in the flow path, there is no interference with the flow itself, and the size of the sphere is small in diameter with respect to the flow path.

(5) Unlike the conventional flow path itself, which forms an annular flow path, the flow path is the simplest because it has the feature of creating an axial flow swirl in the straight pipe section and rotating the magnetic rotating body. The flow path length can be shortened, and the structure is simple and extremely small and compact as a flow rate detection device.

(6) Since the fixed blades are provided only on the upstream side of the sphere, the sphere does not rotate during reverse flow, which has the effect of preventing malfunction of reverse flow detection.

(7) The magnetic detection element is configured to detect the rotation of a sphere orbiting inside the pipe by installing a magnet outside the pipe, and it is easy to electrically insulate the magnetic detection element and the magnet from the fluid. It is possible to obtain a highly practical configuration in which temperature does not directly act on the magnetic detection element or magnet.

[Brief explanation of drawings]

1 and 2 are a horizontal section and a vertical section of a flow path of a conventional flow rate detection device, FIGS. 3 and 4 are sectional views of a flow rate detection device according to an embodiment of the present invention, and FIG. 5 is a sectional view of a flow rate detection device according to an embodiment of the present invention. FIG. 3 is an external perspective view of a fixed wing. 13... Rotating means (fixed wing), 15... Outflow prevention means (center axis), 18... Magnetic rotating body (magnetic sphere), 22... Magnetic detection element, 23... Permanent magnet.

Claims (1)

[Scope of Claims] 1. A fixed vane provided in a pipe to axially swirl the fluid to be detected to generate a swirling flow, and an inner wall of the pipe located in the swirling flow in a direction perpendicular to the flow direction. It consists of a magnetic sphere that rotates in contact with the pipe, an outflow prevention means that keeps the magnetic sphere within the range of the swirling flow, and a rotation detection device that detects the rotational speed of the magnetic sphere. a magnetic detection element provided outside the pipe and on an extension line of the circumferential surface of the magnetic sphere, and outside the pipe and on an extension line of the circumferential surface of the magnetic sphere; a permanent magnet that is provided at a position outside of the range and out of contact with the fluid to be detected and applies a magnetic field to the magnetic detection element. 2. The flow rate detection device according to claim 1, wherein the permanent magnet is provided downstream of the circumferential surface of the magnetic rotating body.