JPH0472174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flow rate detection device that measures a flow rate by replacing the flow rate of a fluid with the rotational speed of a rotating body.

Conventional configuration and its problems Conventional methods for detecting rotation with a rotating body detection type flow sensor include attaching a permanent magnet to the outer periphery of the rotating body and placing a Hall element or magnetic resistance element close to it for detection. Alternatively, there is a method in which a detection section made of a ferromagnetic metal material is detected using a magnetoresistive element equipped with a bias magnet. An example of this will be explained with reference to FIG. The figure shows a vane-wheel type flow sensor, in which fluid flows from the direction of the arrow, rotating a vane wheel 101, whose rotation speed is proportional to the flow rate, and the rotation speed is determined by a permanent magnet 102 provided at the tip of the blade. The rotation is detected as a pulse by a magnetoresistive element 103 provided outside the flow path, and a control circuit (not shown) calculates and measures the flow rate. In this case, as mentioned above, it is necessary to attach permanent magnets to the blades, and it is necessary to devise ways to attach the magnets so that they do not come off over a long period of time.Furthermore, foreign matter such as iron powder in the fluid can easily adhere to the blades and cause rotational problems. Such,
There were problems caused by attaching permanent magnets to the rotating body.

Further, as an example of the structure of the ball in the magnetic ball rotation method, there is an example described in Japanese Patent Application Laid-Open No. 55-9179. It is made of a synthetic resin material mixed with this magnetic powder. Since this configuration is a solid state in which the inside of the ball is completely filled, the amount of magnetic material contained must be small to achieve a specific gravity equivalent to that of the fluid, resulting in poor magnetic properties and a weak output signal. There was a drawback.

In addition, as a conventional example of a floating sphere used in this type of flow rate detection device, there is
There is an example described in Publication No. 60561. This was because the detection sphere was made of synthetic resin to give it floating properties.

Purpose of the invention The present invention solves such conventional problems,
It is an object of the present invention to provide a flow rate detection device that detects the rotation of a rotating magnetic sphere without attaching a permanent magnet to the rotating magnetic sphere.

Structure of the Invention In order to achieve this object, the present invention provides a fixed vane that imparts axial swirl to a fluid to generate a swirl flow, and a magnetic sphere that is located in the swirl flow and revolves in a plane perpendicular to the flow direction. , an outflow prevention means for stopping the magnetic sphere within the range of the swirling flow; a magnetic sensor installed outside the flow path near the circumferential circuit of the magnetic sphere to detect rotation; It consists of a permanent magnet that applies a magnetic field to the magnetic sensor and a control circuit that processes signals from the magnetic sensor, and the magnetic sphere is a hollow resin-formed sphere containing powder, granules, or fibrous magnetic material. be. This configuration makes it possible to obtain a high output signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, 1 is the casing of the flow path 2 of the flow rate detection device, 3 is its inlet, and 4 is its outlet. 5
is a fixed blade that gives a swirling flow to the fluid flowing in the direction of the arrow, has blades that are not parallel to the flow, and is fixed to the casing 1 by press fitting or the like so that it does not rotate due to the flow of the fluid. Numeral 6 is a magnetic sphere that exists in a free state downstream of the fixed blade 5 and rotates in the flow path in a direction perpendicular to the flow due to the swirling flow of the fluid. Numeral 7 is an outflow prevention body for the magnetic sphere 6 and serves as a rotating support for the magnetic sphere 6. Become. A magnetoresistive element (magnetic sensor) 8 is located outside the flow path near the circuit around the magnetic sphere 6, and is fixed to the casing 1 with a fixture 10 together with a permanent magnet 9 that applies a magnetic field to the magnetoresistive element 8. 11 is a control circuit that processes signals from the magnetoresistive element 8; FIG. 3 shows a magnetic sphere 6, which is a hollow resin molded product containing a magnetic material 14 such as iron or ferrite inside.

Next, the operation will be explained. When the fluid flows from the inlet 3 toward the outlet 4, it becomes an axial swirling flow at the fixed blades 5, and the swirling flow causes the magnetic spheres 6 to revolve in the passage. Since the number of revolutions per revolution is proportional to the flow rate,
The rotation speed is detected by the magnetoresistive element 8, and the flow rate is determined by arithmetic processing by the control circuit 11. The direction of the magnetic flux acting on the magnetoresistive element 8 from the permanent magnet 9 changes due to the proximity of the ferromagnetic magnetic sphere 6 containing iron powder, and the magnetic flux acting on the magnetoresistive element 8 changes its direction. It will be detected in pulses. The rotation signal and flow rate detected by the control circuit 11 in this way can be displayed as an instantaneous flow rate of a flow meter, or when this flow rate detection device is incorporated into equipment as a flow sensor, it can be used to start/stop or control the equipment. It will be used for purposes such as serving as a signal source.

In the above embodiment, the rotating body is a sphere, which rotates in an axial flow using fixed blades, and the size of the magnetic sphere 6 is much smaller than the passage area of the flow path 2, and the blades are also fixed and structurally narrow. There are no parts. Therefore, as a flow rate detection device, there is little pressure loss, and the structure is resistant to sewage such as water scale and scale.

The magnetic sensor for detecting the number of rotations may also be of the pick-up coil type, and is not limited to the configuration of the above embodiment.

Effects of the Invention As described above, according to the flow rate detection device of the present invention,
The magnetic sphere is a magnetic body containing powder, granular, or fibrous magnetic material, and since it is not equipped with a permanent magnet, the following effects can be obtained.

(1) The rotation detection signal output of the magnetic sphere can be increased. That is, the S/N ratio increases, the noise resistance of the signal processing circuit increases, and the reliability increases.

The magnetic detection method detects changes in the magnetic field, so the larger the magnetic permeability of the magnetic sphere, especially near the surface, the larger the change in the magnetic field.The problem is how to construct a ferromagnetic material near the surface and make it float. becomes important. In the present invention, the center of the sphere, which has little effect on changes in the magnetic field, is made hollow and contains a larger amount of magnetic material equivalent to its weight, thereby increasing the magnetic permeability near the surface of the sphere and increasing the detection signal. It is possible.

(2) When attaching a permanent magnet to a magnetic sphere, it is necessary to devise a highly reliable attachment so that the permanent magnet does not come off for a long period of time, and also to prevent foreign matter such as iron powder or metal chips in the fluid from coming into contact with the magnetic sphere. Attaching a permanent magnet to a magnetic sphere in a flow path is accompanied by problems such as adhesion and malrotation, but the present invention has a configuration in which the rotation of the magnetic sphere is detected by a magnetic sensor. This is a highly reliable flow rate detection device that is free from the above problems.

(3) Since the magnetic sphere is made of non-metallic material and is lightweight, it is easy to operate even with a small flow of fluid, and has low sensitivity flow rate as a flow rate detection device.

(4) When the magnetic sphere moves while contacting the channel side wall or the outflow prevention body, the magnetic sphere is also softer and lighter than metal, so its kinetic energy is small, and there is less wear due to contact rotation. Generates little noise.

(5) Since the magnetic sphere is formed from a non-metallic material such as resin molding containing a magnetic material, it is easy and inexpensive to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional flow rate sensor, and FIG. 2 is a sectional view showing an embodiment of the flow rate detection device of the present invention.
FIG. 3 is a cross-sectional view of the magnetic sphere of the detection device. 2... Channel, 6... Magnetic sphere, 8... Magnetoresistive element (magnetic sensor), 11... Control circuit, 12,
13, 14...Magnetic material, 5...Fixed wing.

Claims (1)

[Claims] 1. A fixed vane that generates a swirling flow by imparting an axial swirl to the fluid, a magnetic sphere located in the swirling flow and orbiting in a plane perpendicular to the flow direction, and a magnetic sphere placed within the range of the swirling flow. a magnetic sensor provided outside the flow path near the circumferential circuit of the magnetic sphere to detect rotation; a permanent magnet that is close to the magnetic sensor and applies a magnetic field to the magnetic sensor; A flow rate detection device comprising a control circuit that processes signals from a magnetic sensor, and wherein the magnetic sphere is a hollow resin-formed sphere containing powder, granular, or fibrous magnetic material.