JPH0410012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flowmeter that measures the flow rate by detecting the displacement of a free piston that moves within a cylinder due to the supply of fluid using a non-contact type detector. be.

This free piston type flowmeter is suitable for measuring minute flow rates, but the present invention aims to amplify the measurement signal generated by the displacement of this piston to improve the sensitivity that is particularly required for micro flowmeters. purpose.

In order to achieve the above object, the present invention has a free piston having a hollow cylindrical structure, non-contact type detectors are arranged at both ends of the cylinder so as to face the material to be detected on both end surfaces of the free piston, and A four-way valve is provided in the pipe line leading to the front and rear chambers of the cylinder partitioned by the piston to alternately supply and discharge the fluid to be measured into and out of the front and rear chambers as the free piston moves. It is configured so that outputs generated simultaneously from non-contact type detectors at both ends of the cylinder are used as measurement signals, and the configuration will be explained in detail below with reference to the drawings.

1 is a cylinder made of transparent glass, 2 and 3 are lids that close the openings at both ends of cylinder 1, and 4 is a free piston that slides inside cylinder 1. As shown in Figure 2, it is made of non-conductive material such as glass, ceramics, or synthetic resin. Thin end plates 42 and 43 made of a conductive material such as aluminum are inserted into the openings on both end faces of the cylinder 41 made of material as the detection target material.
It is made hollow by lightly press-fitting or gluing. The piston 4 may have a cylindrical portion and both end surfaces formed into a hollow integral piece, and a conductive material foil or the like may be attached to the outside of each end surface.

Non-contact detectors 5, 6 are mounted on the inner surfaces of the lids 2, 3 facing the end plates 42, 43 of the piston 4, respectively.
is attached and connected to a signal converter (not shown). As the non-contact type detectors 5 and 6, a distance sensor for determining the distance to the other party, that is, a commonly used differential transformer type eddy current distance sensor is suitable.

Fluid inlet/outlet ports 9, 10 are opened in the side surfaces of each lid 2, 3, which communicate with a front chamber 7 and a rear chamber 8, respectively, of the cylinder 1, which are partitioned by a piston 4.

The fluid inlet/outlet ports 9, 10 are connected to a pipe 11 leading to a source of the fluid to be measured and a pipe 12 leading to a discharge side of a surge tank or the like through a four-way valve 13 so as to be connectable alternately.

When fluid is sent with the four-way valve 13 set to the position shown by the solid line in Figure 1, the fluid flows from the pipe 11 to the cylinder 1.
flows into the front chamber 7 and causes the piston 4 to retreat. The fluid previously contained in the rear chamber 8 is pushed out by the piston 4 and flows into the pipe 12 via the four-way valve 13.

As the piston 4 retreats, the voltage generated at the front chamber side detector 5 decreases, and at the same time the voltage generated from the rear chamber side detector 6 increases, and the change in voltage can be seen as the amount of displacement of the piston 4. can. That is, no matter which side of the cylinder 1 the piston 4 moves to, the voltage on one side is always high. The flow rate is determined by the piston displacement amount and the time required for the displacement.

When the piston 4 reaches the retraction end, the four-way valve 1
3 by 90 degrees counterclockwise in the figure, the flow path in the four-way valve 13 is switched as shown by the chain line, the direction of fluid inflow into the cylinder 1 is reversed, and the piston 4 moves forward to return to its original position. Return to If the detectors 5 and 6 are activated when the piston 4 is returned, continuous reciprocating measurements can be made.

The present invention provides a free piston type flowmeter using a non-contact type detector, in which the free piston 4 is
It has a hollow cylindrical structure, and non-contact type detectors 5 and 6 are arranged at both ends of the cylinder 1 facing the detected materials 42 and 43 on both end surfaces of the free piston 4, and are partitioned by the free piston 4. A four-way valve 13 is provided in the pipe line leading to the front chamber 7 and rear chamber 8 of the cylinder 1, which alternately supplies and discharges the fluid to be measured to the front chamber 7 and rear chamber 8. Since the configuration uses the outputs generated simultaneously from the non-contact type detectors 5 and 6 at both ends of the cylinder as measurement signals, a buoyant force is generated on the free piston 4, and the piston 4
The friction between the free piston 4 and the cylinder 1 is reduced, and the movement of the free piston 4 becomes smooth, thereby making it more sensitive to minute flow rates of the fluid to be measured and improving detection accuracy.

and non-contact detectors 5 at both ends of the cylinder 1,
Since the two outputs generated simultaneously from 6 are used as measurement signals, even if the free piston 4 is biased to one side in the cylinder 1, one of the detection signals will be large, so the sliding displacement of the free piston 4 can be measured. It can be detected with high accuracy.

Furthermore, since the supply and discharge of the fluid to be measured into and out of the front chamber 7 and rear chamber 8 of the cylinder 1 can be alternately changed by switching the pipe lines using the four-way valve 13, by reciprocating the piston 4, It also has the advantage of being able to perform continuous measurements.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of the flowmeter of the present invention, and FIG. 2 is an exploded perspective view of the free piston. 1 is a cylinder, 2 and 3 are lids, 4 is a free piston, 41 is a cylindrical body, 42 and 43 are materials to be detected, 5 and 6
is a non-contact detector, 7 is the front chamber, 8 is the rear chamber, 9,1
0 is a fluid inlet/outlet, 11 and 12 are pipes, and 13 is a four-way valve.

Claims (1)

[Claims] 1. In a flowmeter that measures the flow rate by detecting the displacement of a free piston that moves within a cylinder due to the supply of fluid with a non-contact detector, the free piston is formed into a hollow cylindrical body. The structure is such that non-contact detectors are arranged at both ends of the cylinder to face the material to be detected on both end surfaces of the free piston, and a conduit leads to a front chamber and a rear chamber of the cylinder partitioned by the free piston. A four-way valve is provided to alternately send and discharge the fluid to be measured into the front chamber and the rear chamber, and the output generated simultaneously from the non-contact detectors at both ends of the cylinder as the free piston moves is used as the measurement signal. A flowmeter featuring: