JPH06347301A - Flow detector - Google Patents

Abstract

PURPOSE:To provide a flow detector wherein the direction of flow of fluid can be judged from the outside of piping. CONSTITUTION:A tube 4 wherein a magnet 2 has been fixed and housed is provided in a fluid flow pipe 1. Ends of plugs 5a, 5b provided with a flow passage are engaged and inserted in both ends of the tube 4. Coil springs 3a, 3b are locked on other ends of the plugs 5a, 5b and the tube 4 is charged with balance through the plugs 5a, 5b. A magnetic sensor is arranged on the outside of the pipe 1 in which the magnet 2 is located. When gas is allowed to flow in the pipe 1, the magnetic sensor detects change of a magnetic field on the basis of the displacement of the magnet since the magnet 2 is displaced in the direction wherein gas is allowed to flow with force which gas gives. Because a flow and the direction of flow are found due to increase or reduction of the magnetic field, the reverse flow of gas can be also detected easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate detecting device in a fluid pipeline for gas, liquid, etc., and more particularly to a flow rate detecting device capable of detecting a reverse flow and an excessive flow rate of a fluid.

[0002]

BACKGROUND OF THE INVENTION Many toxic, flammable gases are used in the semiconductor industry. Since these gases are highly reactive, a backflow in the gas line can easily lead to a major accident.
For example, in a CVD method equipped with monosilane and nitrous oxide equipment, it is very dangerous if nitrous oxide flows back to monosilane through the CVD device or vice versa. Therefore, it is obligatory to install a backflow prevention device in the equipment so that the gases do not flow back to each other.

Therefore, hitherto, a check valve is installed in the gas line in order to prevent backflow, and the gas flows when the positive pressure exceeds a certain differential pressure, but shuts off the gas when the backpressure is applied. I was taking measures against it.

However, even if a check valve is installed in the gas line to take measures against backflow, if the check valve mechanically reverses the flow of gas, a mechanism for stopping the backflow is provided. It is equipped, but it cannot be judged from the outside whether the gas is flowing normally or the backflow is occurring.

Further, it is difficult for the check valve to remove the gas in front of the check valve by vacuuming. Therefore, when the cylinder is replaced or the parts are replaced, the air mixed therein cannot be sufficiently removed, which hinders future manufacturing.

[0006]

SUMMARY OF THE INVENTION In view of the above problems of the check valve, the present invention provides a flow rate detecting device capable of immediately determining from outside whether the gas normally flows or flows backward in the gas line. To propose.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a fluid flow pipe having a fluid flow inlet and a fluid flow outlet, and a magnet fixed in a tube that is biased by springs from both ends in the fluid flow pipe. And a magnetic sensor for detecting a change in the magnetic field based on the displacement of the magnet due to the change in the force exerted by the fluid passing through the fluid flow passage. The fluid flow pipe includes a flow control valve and a shutoff valve, controls the flow rate of the flow control valve based on the output of the magnetic sensor, and drives the shutoff valve to detect gas when reverse flow or overflow is detected. Cut off.

[0008]

1 and 2 show a first embodiment of a flow rate detecting device of the present invention.
FIG. 1 shows a vertical sectional view, and FIG.
AA ′ cross section of FIG. The technical idea of the present invention is
A magnet biased in equilibrium by a spring is provided in the gas flow path, and its position is displaced with respect to the flow path according to the gas flow direction. It is to detect the flow rate and the flow direction by detecting with a magnetic sensor provided.

In FIG. 1, an inner tube 4 having a magnet 2 fixedly housed therein is coaxially provided in an outer pipe 1. The inner tube 4 is loaded by a coil spring 3a and a coil spring 3b so as to be movable left and right. 6
Reference numerals a and 6b denote magnet holding portions that hold the magnet 2 from both sides and are made of quartz wool or the like.

Further, plugs 5a and 5b made of resin such as Delrin are fitted in the inner tube 4. As shown in FIGS. 2 and 3, the plugs 5a and 5b have a plurality of protrusions 8 at the center thereof, which are slidably in contact with the outer pipe 1 to form a gas flow path 10 together with the outer pipe 1. It is formed parallel to the direction. Plugs 5a and 5b
The springs 3a and 3b are fitted into one end of the to form a stopper.

The other ends of the coil springs 3a and 3b have a stepped union 7 connecting the outer pipe 1 and the other pipe 13.
Is locked to the inner stepped portion 7a. In the stepped union 7, the outer pipe 1 is fitted to the outer stepped portion 7b with a cap nut 11 and locked (suji lock).

A magnetic sensor 12 (FIG. 5), which will be described later, is fixedly arranged at a predetermined position on the outer side of the outer pipe 1 for detecting a change in the magnetic field due to the displacement of the magnet 2.

FIG. 4 shows a second embodiment of the present invention. In the first embodiment, the strength of the spring for biasing the magnet 2 is fixed, but in the second embodiment, the coil spring 3a is used.
And a mechanism capable of adjusting the strength of 3b are provided. Less than,
A second embodiment will be described with reference to FIG. The components having the same functions as those in the first embodiment will be described with the same reference numerals.

In FIG. 4, 1 is an outer pipe, 2 is a magnet, 3a and 3b are coil springs, 4 is an inner tube, 5
a and 5b are plugs, and 6a and 6b are magnet holding portions, which are the same as those in the first embodiment.

In the case of the second embodiment, in order to make the strength of the coil springs 3a and 3b variable, a spring adjusting screw 9a having a flow passage 9c and a spring adjusting screw 9b having a flow passage 9d are provided. There is. The spring adjusting screws 9a and 9b
Is screwed to the spring adjustment adapters 14a and 14b connected to the outer pipe 1 by welding 14c or the like. The strength of the spring adjusted by the spring adjusting screws 9a and 9b is adjusted in consideration of the optimum flow rate through the pipe, the viscosity of the fluid, and the sensitivity of the spring to backflow.

The flow rate detection and fluid direction operation of the flow rate detecting device will be described below with reference to the block diagram of FIG. First, the magnetic sensor 12 composed of a Hall element or a magnetoresistive element is fixed to the center of the magnet 2. The magnetic sensor 12 is zero-adjusted to a state where no gas is flowing.

When the gas flows from the upstream side to the downstream side of the flow path of the outer pipe 1, the force exerted by the gas causes the coil spring 3 to move.
a extends, the coil spring 3b contracts, the plugs 5a and 5b slide on the inner wall of the outer pipe 1, and the magnet 2 moves downstream.

When the upstream polarity of the magnet 2 is the S pole and the downstream polarity is the N pole, the N pole or the S pole of the magnet 2 is moved to the magnetic sensor 12 by moving the magnet 2 to the upstream or downstream side. Since the magnetic field to be detected approaches and the detected magnetic field increases, the change in the magnetic field detected by the magnetic sensor 12 can be detected as the change in the position of the magnet 2. The change in the detected magnetic field is converted into an electric signal by the magnetic sensor 12, and the electric signal is input to the amplifier circuit 15.

A backflow detection comparison circuit 16 and an overflow detection comparison circuit 17 are connected to the output side of the amplifier circuit 15,
The backflow detection / comparison circuit 16 detects the backflow by comparing with the backflow detection setting signal, and the overflow detection / comparison circuit 17 detects the overflow by comparing with the overflow detection setting signal.

When a backflow of gas occurs, the magnet 2 slightly displaces or displaces in the opposite direction, and when the backflow set reference value is exceeded, the backflow detection / comparison circuit 16 outputs a backflow signal to drive the drive circuit. 18a drives the relay 19a and the LED lamp 20a to give an alarm.

On the other hand, in the case of overflow detection, by setting 100% flow rate as the reference value, when the output of the amplifier circuit 15 exceeds the overflow setting reference value, the overflow detection comparison circuit 17 causes the overflow rate. A signal is output and the drive circuit 18b drives the relay 19b and the LED lamp 20b to issue an alarm or the like.

In FIG. 5, 21 has been described as a flow control valve, but the flow control valve may be replaced with a shutoff valve. In this case, the output of the amplifier circuit 15 is not directly supplied to the shutoff valve, but when the reverse flow or the overflow is detected, the relay 19a or 19b may be driven to control the shutoff valve. Further, the shutoff valve may be provided in another place of the pipe, and in this case, both the flow control valve and the shutoff valve can be controlled.

In the above detection method, the magnetic sensor 12 detects the strength of the magnetic field of one pole of the magnet 2 to detect the backflow or the overflow, but for example, to the N pole side of the magnet 2. If the displacement of the gas flow is the normal direction of the gas flow and the displacement toward the south pole is the reverse flow direction of the gas, the output of the magnetic sensor 12 for the displacements in the two directions can be detected by reversal, and therefore the reverse flow setting reference value is set. It is possible to set the width (dead zone). Therefore, the reference value can be arbitrarily set in consideration of the type of flowing gas, the pressure of the gas, the adjustment of the spring, and the like.

Since the output of the amplification circuit 15 also detects the current gas flow rate, the output can be supplied to the flow rate control valve 21 to control the flow rate. Further, this change can be displayed and used as a flow meter. Further, as described above, it can be applied to the control of the shutoff valve, and a control device that flexibly responds to the control of the valve can be realized.

In the above-mentioned embodiment, a tube made of SUS316 stainless having an outer diameter of 6 mm and a length of 33.5 mm is used as the inner tube, and an outer diameter of 9.5 m is used as the outer pipe.
As a result of an experiment using a SUS316 stainless steel pipe having a length of 100 mm and a diameter of 5 mm, a length of 5 mm and a magnet having a length of 3800 gauss as a magnet, an increase in magnetic field up to 200 gauss was detected for a positional displacement of 5 mm. We were able to.

Further, as a result of the experiment, a change of 2-16 gauss can be detected even for a slight displacement of 0.1 mm of the magnet, and it is sufficient to detect a change in gas flow rate and a backflow of gas. I was able to respond.

In the above-mentioned embodiment, the inner tube 4 is provided and the magnet 2 is housed therein. However, the inner tube 4 is not housed and is directly housed in the pipe forming the gas passage. Is also possible. Alternatively, the magnet 2 may be attached to the diaphragm for implementation. In the case of the above-described embodiment, the compression spring is used, but it is also possible to use a tension spring.

[0028]

By utilizing the displacement of the magnet due to the force exerted by the gas, the flow rate and the flow direction of the fluid can be easily determined from the outside of the pipe, and the determination of backflow and overflow can be appropriately and easily performed.

Further, since the existing standard pipe can be used, it can be manufactured at a low cost, and it is possible to realize a flow rate detecting device which can be easily attached to and replaced with the gas pipeline currently used.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a flow rate detecting device of the present invention.

FIG. 2 is a sectional view taken along line AA ′ of the first embodiment.

FIG. 3 is a diagram showing an example of a plug used in the present invention.

FIG. 4 is a sectional view of a second embodiment of the flow rate detecting device of the present invention.

FIG. 5 is a block diagram of a detection circuit of the flow rate detection device of the present invention.

[Explanation of symbols]

 1 Outer Pipe 2 Magnet 3 3a, 3b Spring 4 Inner Tube 5a, 5b Plug 6a, 6b Magnet Holding Body 7 Stepped Union 9a, 9b Spring Adjustment Screw 12 Magnetic Sensor 14a, 14b Spring Adjustment Adapter 21 Flow Control Valve or Shutoff Valve

Claims (4)

[Claims] 1. A fluid flow pipe having a fluid flow inlet and a fluid flow outlet, a magnet biased from both ends in the fluid flow pipe by spring equilibrium, and a force exerted by a fluid passing through the fluid flow passage. And a magnetic sensor that detects a change in the magnetic field based on the displacement of the magnet due to the change in the flow rate. 2. The flow rate according to claim 1, wherein a tube containing the magnet, the diameter of which is smaller than that of the fluid flow pipe, is provided in the fluid flow pipe including the fluid flow inlet and the fluid flow outlet. Detection device. 3. The flow rate detection device according to claim 1, wherein the fluid flow pipe is provided with a flow rate control valve, and the flow rate of the flow rate control valve is controlled based on the output of the magnetic sensor. 4. The flow rate detecting device according to claim 1, wherein the fluid flow pipe is provided with a shutoff valve, and the shutoff valve is controlled based on an output of the magnetic sensor.