JPS63228026A - Flow rate detector - Google Patents

Abstract

PURPOSE:To eliminate the influence of magnetic field noises, etc., by putting a magnetic detecting element, and a magnet and a spherical body at close distances and providing the magnet on the downstream side of a spherical body receiver. CONSTITUTION:The spherical body 22 abuts on the peripheral abutting surface 23 and peripheral abutting wall 27 of the spherical body receiver 26 at two points by a swivel flow, and swivels and rotates within the range of a vertical surface 21 at right angles to the flow of fluid. The swiveling speed of this spherical body 22 is determined by the swivel flow rate, but the flow passage area of a fixed vane 20 is constant, so the swivel flow rate is proportion to the flow rate. For the purpose, the swiveling speed of the spherical body 22 is detected to measure the flow rate. A magnetism detecting element 38 is applied with a magnetic field having constant intensity from the magnet 39. In this state, when the spherical body 22 passes below the element 38, the direction of the magnetic flux from the magnet 39 to the element 38 is changed by a metallic bead put in the spherical body 22. Consequently, the magnetic field applied to the element 38 decreases in its intensity and the resistance value of the element 38 varies. This variation is led out as variation in voltage and outputted as pulses. Thus, the influence of magnetic noises, etc., entering the element 38 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flow rate detection device used for the purpose of detecting the flow rate of water or hot water in a water heater or hot water heating device, or for detecting the fuel flow rate in a liquid fuel supply device. It is something.

BACKGROUND OF THE INVENTION There are various types of devices of this type, but one simple means that can be applied to general consumer equipment is one that converts the rotational speed of a movable body such as an impeller that rotates in proportion to the flow rate into an electrical signal. For example, a shaft-supported impeller is installed in the flow path, and a permanent magnet embedded in the outer periphery of the impeller operates a magnetic detection element installed outside the pipe to obtain a pulse output with a frequency proportional to the flow rate. There is. With this method, there is a risk that there is a bearing in the flow path, and the intrusion of foreign matter may cause deterioration of the υ bearing, which reduces rotational speed accuracy, or that iron powder sludge flowing through the flow path may adhere to the permanent magnet in the flow path. There is a risk of deterioration in rotation accuracy. For this reason, there is a type of flow rate detection device that does not have a bearing part or a permanent magnet in the flow path. FIG. 3 shows a conventional example. Reference numeral 1 denotes a housing, which is made of forged brass or cast bronze and has a wall thickness of 2.5 mm or more. The reason for this is the internal nests (
This is stipulated by law to prevent water leakage from spaces (spaces). The inside of the housing 1 is provided with a fixed blade 2 that causes an axial swirl in the flow, and a sphere 3 that rotates downstream of the fixed blade 2 in a plane perpendicular to the direction of the flow due to the swirl flow. There is. This spherical body 3 is constructed by providing a sphere made of metal or 7/7/2 metal inside which is attracted by a magnet, and molding the outer periphery with resin. Downstream of the sphere 3, there is a circumferential contact surface 4 with which the sphere 3 comes into contact, and an inner flow path 5.
and a spherical receiver 7 having an outer flow path 6.

A rotation converter 8 composed of the fixed blade 2, the sphere 3, and the sphere receiver 7 is fixed inside the shaft/seat ring 1 by a C ring 9. 10.11 shows the entrance and exit. On the other hand, a detector 12 for detecting the rotation of the sphere 3 is attached to the outside of the housing 1 in close contact with the housing 1. Inside the detector 12, there is a magnetoresistive element 14 soldered to a circuit board 13, a magnet 15 that provides a magnetic field to the magnetic detection element 14, and a vertical surface 16 in the range around which the sphere 3 revolves, and a sphere receiver 7. It is located above the 17 is an electronic circuit for amplifying the output signal of the magnetoresistive element 14 and then shaping it into a pulse waveform. 18 is a contact wall when the sphere 3 revolves.

Next, the operation in the conventional example will be explained. The fluid entering from the inlet 10 becomes a swirling flow at the fixed blade 2. The flow velocity of this swirling flow is proportional to the flow rate because the flow path area of the fixed blade 2 is constant. The sphere 3 placed in this swirling flow orbits the vertical surface 16 at a rotation speed proportional to the flow rate while contacting the orbiting abutment surface 4 and the abutment wall 18. Therefore, by detecting the rotation of the sphere 3, the flow rate can be measured. The principle of detection is that when the sphere 3 passes below the magnetoresistive element 14 while a magnetic field is acting on the magnetoresistive element 14, the sphere 3
The strength of the magnetic field applied from the magnet 15 to the magnetoresistive element 14 changes due to the influence of the internal metal ball. The change in resistance of the magnetoresistive element 14 due to the change in the magnetic field is detected as a change in voltage, amplified by the electronic circuit 17, and then shaped into a pulse waveform and output.

In the conventional example, since the wall thickness of the housing 1 is ensured to be 2.5 mm or more, even if the magnet 15 is provided above the abutting wall 18 of the sphere 3 or the sphere receiver 7, the wall thickness of the housing 1 is ensured. Even if the strength of the magnetic field is weak and fine iron powder flows through the fluid,
The abutting wall 18 had a structural advantage in that iron powder did not adhere to it.

Problems to be Solved by the Invention However, the above configuration has the disadvantage that the output signal of the magnetoresistive element 14 is small. The reason is that since the wall thickness of the housing 1 is 2.5- or more, the distance between the magnetoresistive element 14 and the magnet 15 and the sphere 3 is long.
This is because the change in the resistance value of the magnetoresistive element 14 when the sphere 3 passes below the magnetoresistive element 14 and the magnet 15 becomes small. As a result, the output voltage is small. Since the output signal is small in this way, in the past, the amplification factor was increased and pulse output was performed. However, when a weak signal is processed by increasing the amplification factor, there is a problem with magnetic field noise emitted from the coil of an AC motor installed near the current detection device, and strong electric field noise such as from radio waves. The structure is such that the distance between the magnet, which is easily affected by the worst effect, and the magnet and the sphere are made close to each other, and the magnet is provided on the downstream side of the sphere receiver.

Effect: With the above configuration, the present invention increases the strength of the magnetic field in the orbiting region of the sphere, thereby increasing the amount of change in the magnetic field acting on the magnetoresistive element when the sphere passes below the magnetoresistive element. , the amount of change in the resistance value of the magnetoresistive element is increased, and the signal output can be increased. Furthermore, by installing a magnet on the downstream side of the sphere receiver, even if fine iron particles in the fluid adhere to the inner wall of the flow path, they will not adhere to the sphere's orbiting area, and the orbital rotation of the sphere will always be kept stable, ensuring accuracy. do.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In Figures 1 and 2, 19 is a non-magnetic thin-walled member...a copper pipe that constitutes the housing, and its wall thickness is 0.
．． About 5 to 1 tumor is used.

A fixed blade 20 is provided inside the copper pipe 19 as a swirling means for generating a swirling flow. A sphere 22 is provided on the downstream side of the fixed blade 2o and revolves in a swirling flow in a plane 21 perpendicular to the flow direction. Here, the vertical plane 21 indicates the entire circumferential region (range indicated by the arrow) in which the sphere 22 circulates. There are various structures for the sphere 22, but a typical example is to press a thin plate of stainless steel, which is attracted by a magnet and is resistant to rust, into a hemisphere, and then press two hemisphere presses against each other to form a sphere. The sphere 22 is completed by sandwiching the stainless steel sphere between two resin hemispheres also molded into hemispheres, ultrasonically welding the mating surfaces of the resin hemispheres, and then polishing. In addition, as another method for making a stainless steel hemisphere, a composite material made by mixing resin with So7 Toferrite is molded into a hemisphere, and two of these molded hemispheres are put together to make a sphere. There is also one constructed as a sphere 22 by this means.

A sphere receiver 26 is provided downstream of the sphere 22 and has a circumferential contact surface 23 on which the sphere 22 comes into contact, an inner flow passage 24, and an outer flow passage 25. Reference numeral 27 denotes a rotating abutment wall that the sphere 22 comes into contact with when it rotates.

The rotation converting section 28, which is composed of the fixed blade 20, the sphere 22, the sphere receiver 26, and the orbiting abutment wall 27, and which converts the flow into orbital rotation of the sphere 22, is sandwiched between an inlet joint 29 and an outlet joint 30. It is provided inside the copper pipe 19. The copper pipe 19, the inlet joint 29, and the outlet joint 30 are sealed by O-rings 31 and 32. Further, the inlet joint 29 and the outlet joint 30 are connected to the bent end 33 of the copper vibe 19.
and 34 are constructed to prevent removal.

On the other hand, outside the copper pipe, a detector 35 for detecting the rotation of the sphere 22 and outputting pulses is provided in close contact with the copper vibrator 19 through a fixed part 36. The detector 35
A magnetoresistive element 3B, which is a magnetic detection element partially attached to a circuit board 37, is provided inside the sphere 22 and located above the sphere 22.

Further, a magnet 39 that applies a magnetic field to the magnetic resistance element 38 is positioned and fixed on the downstream side of the spherical receiver 26. 4o is an electronic circuit for amplifying the signal from the magnetoresistive element 3 and shaping it into a pulse waveform.

The non-magnetic thin-walled members that make up the housing include metal pipes such as copper pipes, as well as resin vibrators, but they are not limited to pipe shapes. It may also be a housing.

Next, the operation in this embodiment will be explained.

The fluid entering from the inlet joint 29 side is turned into a swirling flow by the fixed blades 20 and flows downstream. The sphere 22 placed in this swirling flow is moved by the swirling flow to the orbiting contact surface 23 of the sphere receiver 26.
and the rotating abutting wall 27, and rotates in a direction perpendicular to the fluid flow within the range of the vertical surface 21. This sphere 22
The rotational speed of the fixed wing 20 is determined by the swirling flow velocity.
Since the flow path area of is constant, the swirling flow velocity is proportional to the flow rate. Therefore, by detecting the number of rotations of the sphere 220, it is possible to measure the flow rate. Next, the principle of detecting the circular rotation of the sphere 22 will be explained. A magnetic field of constant strength is applied to the magnetoresistive element 38 from a magnet 39. In this state, when the sphere 22 rotating around due to the swirling flow passes below the magnetoresistive element 3, the direction of the magnetic flux coming out from the magnet 39 toward the magnetoresistive element 38 changes to the sphere 22.
It is bent by a metal ball inserted inside 2. As a result, the strength of the magnetic field applied to the magnetoresistive element 38 weakens, and the resistance value of the magnetoresistive element 38 changes. This change in resistance value is extracted as a voltage change, amplified, waveform shaped, and output as a pulse. Therefore, one pulse output is obtained per rotation of the sphere 221. To actually measure the flow rate, the instantaneous flow rate can be measured by measuring the pulse interval time, and the cumulative flow rate can be measured by integrating the number of pulses.

In the above configuration, since the housing is made of a copper pipe which is a non-magnetic thin-walled pipe, the strength of the magnetic field acting on the magnetoresistive element 38 increases, so when the sphere 22 passes below the magnetoresistive element 38, The amount of change in the magnetic field acting on the magnetoresistive element 38 increases, and the magnetoresistive element 38
It is possible to take a large change in resistance value, and to increase the output signal. Furthermore, since the magnet 39 is located downstream of the sphere receiver 26, the magnetic field strength on the vertical plane 21 around which the sphere 22 revolves is weak, so that the fine iron powder flowing in the fluid is affected by the rotation of the sphere 22. It is possible to obtain stable rotation of the sphere 22 without adhering to the orbiting abutment surface 23 or the orbiting abutment wall 27 that come into contact with the sphere 22, thereby ensuring accuracy.

Effects of the Invention As described above, the flow rate detection device of the present invention includes a swirling means for axially swirling the fluid to be detected flowing in a flow path, and a swirling means located in the swirling flow caused by the swirling means and arranged in a plane perpendicular to the flow direction. a sphere orbiting at a speed, a sphere receiver located downstream of the sphere and having an orbiting contact surface for the sphere, a magnetic detection element for detecting the number of rotations of the sphere, and processing a signal from the magnetic detection element. Even if the electronic circuit is provided with the rotating means inside, the lower position of the magnetic detecting element is a housing made of a non-magnetic thin-walled member, and the lower position of the magnetic detecting element is provided with a housing made of a non-magnetic thin-walled member, and the magnetic detecting element is located downstream of the spherical receiver and is provided outside the housing. The configuration including a magnet that applies a magnetic field to the detection element has the following effects.

(1) The performance of the detector can be improved. That is, since the signal level from the magnetic detection element is improved, the S/N ratio becomes higher, so that it becomes resistant to magnetic field noise from the AC morph directly applied to the magnetic detection element. Furthermore, since the signal amplification gain can be reduced by improving the S/N ratio, it becomes resistant to strong electric field noise such as ham radio directly connected to electronic circuits.

(2) The size and cost of the detector can be reduced. That is, S/
The improvement in N simplifies the amplifier circuit and reduces the number of control parts, making it possible to achieve smaller size and lower cost than in the past.

(3) Accurate flow rate detection is always possible. In other words, the fine iron powder flowing in the fluid does not adhere to the surface that the sphere comes into contact with, so even if fine iron powder flows through practical piping, it does not affect the rotation of the sphere, resulting in high accuracy. Flow rate detection becomes possible.

As described above, the present invention realizes a flow rate detector that improves performance by thickening the signal of the magnetic detection element and is not affected by iron powder, etc., and has excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a flow rate detection device showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA' in FIG. 1, and FIG. 3 is a sectional view of a conventional flow rate detection device. . 19... Housing, 20... Swivel means, 22... Sphere, 26... Sphere receiver, 37... Electronic circuit 38... ...Magnetic detection element, 39...Magnet. Name of agent: Patent attorney Toshio Nakao and 1 other person19
- Housing n - Swivel + stage 22 - Ball 26 - Ball receiver, D - m - Electronic circuit field - Magnetic detection element n - Magnet Figure 1 Figure 2

Claims (2)

[Claims] (1) A swirling means for axially swirling the fluid to be detected flowing in a flow path, a sphere located in the swirling flow caused by the swirling means and orbiting in a plane perpendicular to the flow direction, and a sphere located downstream of the sphere. and at least a spherical receiver having an orbiting contact surface of the spherical body, a magnetic detection element for detecting the orbiting rotation speed of the spherical body, an electronic circuit for processing a signal from the magnetic detection element, and the turning means. A flow rate detection device comprising: a housing in which a position below the magnetic detection element is made of a non-magnetic thin-walled member; and a magnet located downstream of the spherical receiver and provided outside the housing to apply a magnetic field to the magnetic detection element. (2) The flow rate detection device according to claim 1, wherein the housing is constructed from a non-magnetic metal pipe.