JP2625637B2 - Fluidic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a fluidic flow meter for measuring a flow rate by detecting a fluid vibration.

[0002]

2. Description of the Related Art In the case of a conventional fluidic flow meter, as shown in FIG.
A valve seat 5 is formed in a gas passage 4 leading to the nozzle 3 of the first embodiment, and an emergency shutoff valve 6 for opening and closing the valve seat 5 is incorporated. The emergency shutoff valve 6 is closed in case of emergency such as abnormal gas flow rate or earthquake. A safety mechanism that shuts off gas is incorporated. In the figure, reference numeral 7 denotes a gas outlet.

[0003] Fluidic flowmeters are greatly affected by fluctuations in gas pressure because of the mechanism for detecting fluid vibration. In particular, if there is a large fluctuation in the gas pressure at a small flow rate, the fluid vibration is irregularly generated, which adversely affects the flow rate measurement. Therefore, conventionally, as shown in FIG. 6, a solution is adopted in which a throttle a is incorporated in the gas flow path 4 and a large fluctuation in gas pressure is absorbed by the throttle a.

[0004]

However, the method of incorporating the throttle a in this manner has a problem that when a large flow rate flows, a resistance, that is, a pressure loss occurs, and when the pressure loss increases, the supply gas pressure decreases. Occurs. For example,
As shown in FIG. 7, the pressure loss ΔP is acceptable, if incorporating diaphragm a maximum flow rate Q ₁ is smaller available in the pressure loss that is acceptable as shown by ₁ line P, do not incorporate stop a the maximum flow rate Q _max available increases in pressure loss that is acceptable as shown by P ₂ If.

An object of the present invention is to propose a fluidic flow meter with an emergency shut-off valve, which can regulate the influence of gas pressure fluctuation at a small flow rate while minimizing the pressure loss as much as possible.

[0006]

The configuration of a fluidic flow meter according to the present invention is as follows. In a fluidic flow meter that incorporates an electric emergency shutoff valve in the gas flow path from the gas inlet to the nozzle portion of the fluidic element, a small hole is provided at the center of the emergency shutoff valve, and the small hole is opened and closed. If the gas flow rate is below a certain flow rate, control the emergency shutoff valve to close and the control valve to open,
A fluidic flow meter having a controller that controls opening and closing of an emergency shut-off valve and opening or closing of a control valve when the flow rate is equal to or more than a predetermined flow rate, and that closes both the emergency shut-off valve and the control valve during emergency shut-off.

The object of the present invention also includes a fluidic flow meter in which a flow sensor is installed in the nozzle portion and when the flow rate is small, the flow rate is measured by the flow sensor.

[0008]

The gas reaches the nozzle from the gas inlet via the emergency shutoff valve, flows out of the nozzle into the fluid vibration generating chamber, and generates fluid vibration. The flow rate calculation circuit calculates the flow rate based on the fluid vibration.

In this operation, when the flow rate flowing into the fluidic element decreases below a certain amount, the emergency shutoff valve is closed and only the control valve is open. This control is performed by the controller based on the flow rate measured by the flow rate calculation circuit.

[0010] When the flow rate increases to a certain amount or more, the emergency shutoff valve opens. At this time, the control valve may be left open or closed.

When the emergency shutoff signal is input, the control valve is closed together with the emergency shutoff valve.

[0012]

1 shows a fluidic flow meter according to the present invention. 1 is a fluidic element, 2 is a gas inlet, 3 is a nozzle, 4 is a gas flow path from the gas inlet 3 to the nozzle 4, 5
Is a valve seat formed in the gas flow path 4, 6 is an emergency shutoff valve, and 7 is a gas outlet.

Reference numeral 8 denotes a small hole provided in the emergency cutoff valve 6, 9 denotes a control valve for opening and closing the small hole 8, 10 denotes a solenoid for operating the emergency cutoff valve 6, and 11 denotes a solenoid for operating the control valve 9. In the case of the embodiment, the solenoid 11 is fixed to the operating shaft 12 of the emergency shutoff valve 6, and when the emergency shutoff valve 6 opens and closes, the solenoid 11 and the control valve 9 move together.

Reference numeral 13 denotes a controller.
The following control is performed. When the flow rate calculated by the flow rate calculation circuit 14 that calculates the flow rate based on the signal generated by the fluidic element 1 is equal to or less than a certain flow rate, a signal is sent to the solenoid 10 and the emergency shutoff valve 6 is closed as shown in FIG. , Only the control valve 9 is opened. As a result, gas flows only from the small holes 8. Then, when the flow rate is equal to or more than a certain amount, as shown in FIG.
The emergency shutoff valve 6 is opened. At this time, the control valve 9 remains open. However, the control valve 9 may be closed. When an emergency shutoff signal is input, a signal is sent to both solenoids 10 and 11 to close both emergency shutoff valve 6 and control valve 8.

[0015]

Since the present invention has the above configuration,
The following effects are obtained. a. Since the gas flows through the small hole (throttle) only at a small flow rate, the influence of the gas pressure can be suppressed to the minimum when the gas pressure fluctuates. b. In the case of a large flow, the pressure loss is small because the emergency shutoff valve is opened. c. Since only a small hole and a control valve for opening and closing the small hole need to be incorporated in the emergency shut-off valve, the response is simple, and there is no need to externally attach, for example, a governor for pressure adjustment as in the related art.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a fluidic flow meter according to the present invention.

FIG. 2 is an explanatory diagram of an emergency shutoff valve and a control valve.

FIG. 3 is an explanatory diagram of a situation where an emergency shutoff valve is closed and a control valve is opened.

FIG. 4 is an explanatory diagram of a situation where an emergency shutoff valve is opened.

FIG. 5 is an explanatory diagram of a situation in which both an emergency shutoff valve and a control valve are closed.

FIG. 6 is an explanatory diagram of a conventional fluidic flow meter.

FIG. 7 is an explanatory diagram showing a relationship between a pressure loss and a flow rate when a throttle is inserted and when it is not inserted;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluidic element 2 Gas inlet 3 Nozzle 4 Gas flow path 5 Valve seat 6 Emergency shutoff valve 7 Gas outlet 8 Small hole 9 Control valve 10.11 solenoid 12 Operating shaft 13 Controller 14 Flow rate operation circuit

Claims (1)

(57) [Claims] 1. A fluidic flow meter in which an electric emergency shutoff valve is incorporated in a gas flow path from a gas inlet to a nozzle portion of a fluidic element, wherein a small hole is provided at the center of the emergency shutoff valve. A control valve for opening and closing these small holes is provided, and when the gas flow rate is below a certain flow rate, the emergency shutoff valve is closed and the control valve is controlled to open. A fluidic flow meter having a controller that controls the valve to be closed and controls both the emergency shutoff valve and the control valve to be closed during an emergency shutoff.