JPS6051652B2 - Flowmeter - 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.

In order to maintain good sensitivity of this free piston type flowmeter, it is necessary to keep the inside of the cylinder clean at all times.
The present invention has been proposed in view of the above, and its gist is that a cylinder is filled in advance with a fluid that is difficult to diffuse against the fluid to be measured. Further, the amount of the difficult-to-diffuse fluid filled in front and behind the piston is larger than the stroke volume caused by the displacement of the piston.

The structure of the embodiment shown in the drawings will be explained below. 1 is a transparent glass cylinder, 2 and 3 are lids that close the openings at both ends of the cylinder 1, and 4 is a free piston that slides inside the cylinder 1. An end plate 41 made of a conductive material such as aluminum is bonded or lightly press-fitted into the end opening of a cylinder made of a non-conductive material such as resin as a detection target material. The piston 4 can also be hollow by closing both end faces. A non-contact displacement detector 5 using eddy current is attached to the inner surface of one lid 2 facing the end plate 41 of the piston 4, and is connected to a signal converter (not shown).

A fluid inlet/outlet 8 which communicates with the front chamber 6 and rear chamber 7 of the cylinder 1 partitioned by the piston 4, respectively, is provided on the side surface of each lid 2, 3;
9 is open.

The fluid ports 8, 9 are connected to a pipe 10 leading to the source of the fluid to be metered.
and a pipe 11 leading to the discharge side of a surge tank or the like through a four-way valve 12 so as to be connectable alternately.

'' Then, in the cylinder 1, there is a fluid B that is difficult to diffuse with respect to the fluid to be measured A, such as water for gasoline, alcohol for lubricating oil, etc., and is clean and has no risk of corroding the cylinder 1 or the piston 4. Filled.

The filling amount of fluid B before and after the piston 4 is set to be larger than the maximum stroke volume due to the displacement of the piston 4.

When the fluid A to be measured is sent with the four-way valve 12 set to the position shown by the solid line, the fluid B in the front chamber 6 is pushed by the fluid A, causing the piston 4 to retreat. Fluid B in the rear chamber 7 and fluid A in the tube 11 are pushed out by the piston 4. As the piston 4 retreats as described above, the voltage generated at the detector 5 increases, and this voltage can be seen as the displaced position of the piston 4.

Therefore, the flow rate can be determined from the displacement position and the time required for the displacement. When the piston 4 reaches the retraction end,
By turning the four-way valve 12 90 degrees counterclockwise in the figure, the flow path within the four-way valve 12 is switched as shown by the chain line, the direction of fluid A flowing into the cylinder 1 is reversed, and the piston 4 moves forward. Return to original position.

The present invention is a free piston type flowmeter using a non-contact type detector, in which the cylinder 1 is filled in advance with a fluid B that is difficult to diffuse with respect to the fluid A to be measured. Even if the fluid A is a chemical, an erosive fluid, a polluted fluid, etc., it can be measured.

In addition, since the filling amount of the difficult-to-diffuse fluid B before and after the piston 4 is made larger than the stroke volume caused by the displacement of the piston 4, the fluid A to be measured flows into the cylinder 1.
can be reliably prevented from entering.

Therefore, the sliding portion between the piston 4 and the cylinder 1 is always kept clean, the sensitivity is improved, and accurate measurements can be made, making it suitable for measuring minute flow rates.

In the figure, reference numerals 13 and 14 indicate separation chambers for foreign matter, air bubbles, etc. in the fluid A, which are provided in the respective pipes 10 and 11 between the cylinder 1 and the switching cock 12.

[Brief explanation of the drawing]

The figure is a longitudinal sectional front view of the flowmeter of the present invention. 1 is a cylinder, 2 and 3 are lids, 4 is a piston, 41 is a material to be detected, 5 is a detector, A is a fluid to be measured, and B is a fluid that is difficult to diffuse.

Claims (1)

[Scope of Claims] 1. In a flowmeter that measures the flow rate by detecting the displacement of a free piston that moves within the cylinder due to the inflow of fluid with a non-contact detector, the fluid to be measured is placed in the cylinder. On the other hand, this flowmeter is characterized by being pre-filled with a fluid that is difficult to diffuse. 2. In a flow meter that measures the flow rate by detecting the displacement of a free piston that moves inside the cylinder due to the inflow of fluid with a non-contact detector, a fluid that is difficult to diffuse against the fluid to be measured is placed in the cylinder. A flowmeter characterized in that the amount of the fluid that is difficult to diffuse before and after the piston is filled in advance and is larger than the stroke volume caused by the displacement of the piston.