JPH0317215Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an impeller-type flowmeter, and particularly to an impeller-type flowmeter with good starting characteristics.

[Technical background of the invention and its problems] In general, an impeller type flow meter is required to be able to start rotation even with an extremely small flow rate when rotating the impeller from a stopped state. In order to improve the startup characteristics, the following two methods have been conventionally used.
Improvements are being made from two directions.

1. Narrow down the diameter of the nozzle that sends fluid into the impeller chamber, increase the jet energy from the nozzle, and guide it to the impeller.

2. Reduce the static friction moment by making the impeller smaller in mass.

However, when trying to improve the startup characteristics from the direction of 1) above, the flow rate per unit pressure loss decreases due to narrowing the nozzle diameter, and the pressure loss when the target flow rate passes through increases rapidly. As a result, there was a problem that the possible range of flow rate measurement was narrowed.

Furthermore, when attempting to improve the starting characteristics from the direction of 2) above, there is a natural limit to the reduction in mass of the impeller, and further improvements are difficult in terms of production technology.

[Purpose of the invention] This invention was made in view of such conventional problems, and it is an impeller that can improve the starting characteristics without narrowing the nozzle diameter or reducing the mass of the impeller. The purpose is to provide a type flow meter.

[Structure of the device] In this device, in the lower bearing that supports the shaft of the impeller, a flat stone that supports the lower end of the shaft is connected to a diaphragm, and a vibration device that causes vibration in the axial direction of the diaphragm is connected to the diaphragm. The gist of this paper is an impeller-type flowmeter characterized by the following features.

[Example of the invention] Hereinafter, an example of the invention will be explained in detail based on the drawings.

The drawing shows an embodiment of this invention, in which an impeller 3 constructed by attaching a plurality of impellers 1 around a shaft 2 is housed in a housing 4.

The upper and lower parts of the shaft 2 are supported by an upper bearing 5 and a lower bearing 6, respectively. The lower bearing 6 has a structure in which a hole stone 8 and a flat stone 9 are provided above and below in a main body 7 with a collar 10 interposed therebetween. The lower circumference of the shaft 2 is supported by a hole stone 8, and the lower end of the shaft 2 is supported by a flat stone 9.

A diaphragm 11 made of soft iron such as rubber is provided in close proximity to the lower bearing 6.
A vibration device 12 is connected to 1.

The vibration device 12 includes a vibrator 13 and an excitation coil 14.
An oscillator 15 is connected to this excitation coil 14, and the amplitude of the vibration of the vibrator 13 is measured by the vibration plate 1.
1 and a horn 16 that transmits the signal to the terminal.

The operation of the impeller type flowmeter having the above configuration will be explained next.

The impeller 3 rotates at a speed proportional to the injection speed when fluid injected into the impeller chamber from a nozzle (not shown) provided in the housing 4 hits the impeller 1. Then, the flow rate is measured based on the rotation speed of the impeller 3.

Therefore, when the oscillator 15 energizes the excitation coil 14 to excite the vibrator 13, the diaphragm 11 is vibrated in the longitudinal direction of the shaft 2 via the horn 16.

The vibration of the diaphragm 11 causes the flat stone 9 of the lower bearing 6 to also vibrate, making it possible to create a state of non-contact with the lower end of the shaft 2 at regular intervals.

In this state, the entire impeller 3 is suspended in the air, so that the energy necessary to spray fluid onto the impeller 1 and start its rotation is absorbed by the lower end of the shaft 2 that is constantly in contact with the flat stone 9. It is smaller than if it were installed.

In other words, in a simple model, the robot remains suspended in the air for half the time compared to a case without this vibration system, and therefore requires half the activation energy.

Note that the frequency of the vibration device 12 is experimentally determined by adjusting the oscillator 15 to a value that allows the impeller 3 to start at the lowest flow rate.

Note that constant vibration leads to unnecessary power consumption and wear and tear on bearings, etc., so it goes without saying that vibration is applied only when necessary to help start up the flowmeter.

The case where it is deemed necessary is the case where it is necessary to detect a small fire, and for example, the following means may be used as a trigger for activation of the vibration device.

(1) A valve is installed in front of the flowmeter, and a strain gauge is installed to link with the opening and closing of this valve, and the threshold value of the strain gauge that occurs when the valve is opened is used as a trigger for the activation of the vibration device.

(2) Place pressure sensors before and after the flow meter, and use the differential pressure as a trigger for the vibration device operation.

Regarding the period during which the vibration device is operated, in the case of (1) mentioned above, it is sufficient to set the operation range of the vibration device according to the opening degree of the valve in advance, and in the case of (2), the operation range of the vibration device according to the opening degree of the valve can be set in advance. The operating range of the vibration device based on the pressure difference between the pressure sensors arranged before and after the pressure sensor may be set in advance.

[Effects of the invention] This invention connects a diaphragm to a flat stone that supports the lower end of the impeller shaft, and vibrates this diaphragm in the axial direction. By shortening the time during which a static load is applied to the shaft in the contact state, the static friction moment can be correspondingly reduced and the necessary starting energy can be reduced.

Therefore, the starting characteristics can be easily improved without making efforts such as narrowing down the diameter of the nozzle to the impeller chamber or making the impeller as light as possible as in the past.

[Brief explanation of the drawing]

The drawing is an explanatory cross-sectional view showing one embodiment of this invention. 1... Impeller, 2... Shaft, 3... Impeller, 4
...Casing, 5...Upper bearing, 6...Lower bearing, 7
... Main body, 8 ... Hole stone, 9 ... Flat stone, 10 ... Color, 11 ... Vibration plate, 12 ... Vibration device, 13
... Vibrator, 14 ... Excitation coil, 15 ... Oscillator, 16 ... Horn.

Claims (1)

[Scope of utility model registration request] An impeller type characterized in that, in a lower bearing that supports the shaft of the impeller, a flat stone that supports the lower end of the shaft is coupled to a diaphragm, and a vibration device that causes vibration in the axial direction of the diaphragm is connected to the diaphragm. Flowmeter.