JPS6326727Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a flow rate sensor that measures the flow rate of a fluid by using a magnetic sensor to detect the rotation of a permanent magnet that rotates together with an impeller. The present invention relates to a magnetic sensor type flow rate sensor that minimizes the rotational resistance applied to an impeller when fluid is flowing, and increases the rotational resistance when the flow of fluid stops to rapidly stop the impeller.

(b) Prior Art Conventionally, the rotational resistance of an impeller has been reduced in order to improve the accuracy of measuring small flow rates by reducing the minimum detected flow rate by a flow sensor.

An example of a conventional flow rate sensor in which the rotational resistance of the impeller is reduced is shown in FIG. 1, for example. This conventional flow rate sensor has a rotating shaft c provided in a flow rate b formed in a main body a, one end (the upper end in the figure) of the rotating shaft is supported by a bearing e of a cover d attached to the main body a, and A recess f is formed at the other end (the end on the inlet side of the flow path b), and the rounded tip of the pivot shaft h fixed to the rectifying member g provided at the inlet of the flow path is brought into contact with the recess f, and the rotating shaft is The other end is supported at one point by a pivot shaft.

However, in such a structure, although the rotational resistance of the impeller is reduced, the impeller tends to continue rotating due to inertia even after the fluid flow has stopped, and after the flow has stopped, the impeller will continue to rotate. There is a problem in that the response characteristics (rise response characteristics) until stopping are poor. In general, the minimum flow rate detection characteristics and falling response characteristics are contradictory; if you try to improve the minimum flow rate detection characteristics by reducing the rotational resistance of the impeller, the falling response characteristics will decrease, and conversely, the rotational resistance will increase. If you try to make it larger to improve the falling characteristic, the minimum flow rate detection characteristic will deteriorate.

(c) Purpose of the invention The present invention was created in view of the problems with conventional flow rate sensors, and its purpose is to reduce the rotational resistance of the impeller when the fluid starts to flow or when the fluid is flowing. It is an object of the present invention to provide a flow rate sensor that can improve not only the minimum flow rate detection characteristic but also the falling response characteristic by minimizing the resistance and increasing the rotational resistance when the fluid flow is stopped or reversed.

(d) Structure of the invention The present invention is such that an impeller is rotatably provided in a flow path formed in a main body, a permanent magnet is attached to the rotating shaft of the impeller, and the permanent magnet is rotated together with the impeller. In the flow rate sensor, which detects the rotation of the permanent magnet with a magnetic sensor, a recess is provided at one end of the rotating shaft on the impeller side, the recess is supported by a rectifying member attached to the main body, and the flow sensor is connected by a spring. The tip of the pivot shaft that is pressed against the rotating shaft side can be brought into contact with the pivot shaft, and the other end of the pivot shaft is made into a curved surface so that the other end can come into contact with the bearing part on the main body side, thereby preventing backflow in the flow path. When generated, the impeller is configured to move toward the flow regulating member against the elastic force of the spring and engage with the flow regulating member due to the reverse rotational force acting on the impeller.

In the above configuration, when the fluid flows in the flow path in a normal direction, the other end of the impeller, which has a rounded rotating shaft, engages with the bearing portion and rotates, and the rotation is detected by the magnetic sensor. When a reverse flow occurs in the flow path, such as when the outlet side is closed, a reverse rotational force acts on the impeller.
The impeller is moved in the axial direction against the spring and engaged with the rectifying member to stop the impeller from rotating.

(E) Embodiment An embodiment of the flow rate sensor according to the present invention will be described below with reference to FIG. In the figure, 1 is a flow rate sensor, 2 is a main body in which a flow path 20 is formed, and 3
4 is a rectifying member provided on the inlet side 20a of the flow path 20, 4 is a rotating shaft provided in the flow path of the main body 2, and 5
Reference numeral 6 indicates an impeller of a known structure provided at the lower part of the rotating shaft 4, and 6 indicates a magnetic plate which is attached to the upper part of the rotating shaft 4 and has a permanent magnet 61 embedded therein.

The upper end 40 of the rotating shaft 4 is rounded and rotatably supported by a bearing 7 embedded in the inner surface of a cover 21 attached to the upper end of the main body 2. A pivot bearing 43 having a recess 44 formed in the lower end is fixed to the lower end of the rotating shaft (on the inlet side of the flow path). The rounded upper end of the pivot shaft 8 is brought into contact with the recess 44, thereby supporting the lower end of the rotary shaft 4 at one point.

The pivot shaft 8 is inserted into a screw hole 31 of the rectifying member 3 so as to be able to move up and down, and is pressed toward the rotating shaft side by a spring 10 provided between the pivot shaft 8 and an adjustment screw 9 screwed into the screw hole. . When the outlet side of the flow path is closed and the flow of fluid is stopped, the spring 10 is deflected by the axial component of the force acting on the impeller from the outlet side, and the lower surface of the impeller 5 is bent to the upper surface of the rectifying member 3. It is strong enough to be able to touch.

A rectifying passage 32 extending in the axial direction of the rotating shaft is formed in the rectifying member 3, and is configured to apply fluid to the surface of the blade of the impeller 5 (fixed obliquely with respect to the axis). A magnetic sensor 11 is attached to the main body 2 at a position close to the magnet plate 6.

In the flow rate sensor configured as described above, when fluid flows from the inlet side of the flow path to the outlet side through the rectification passage 32, the impeller 5 and the permanent magnet 61 rotate at a speed proportional to the flow rate. The rotation of the permanent magnet is detected by a magnetic sensor to measure the flow rate.

When the outlet side of the channel is closed and the flow of fluid stops, or when the fluid tries to flow from the outlet side to the inlet side, a reverse rotational force acts on the impeller 5, and the axial component of the force causes the impeller 5 to rotate. The wheel 5 is pushed down together with the rotating shaft 4 against the pressing force of the spring 10, and the impeller 5
The lower surface of the rectifying member 3 contacts the upper surface of the rectifying member 3 . Therefore, rotational resistance acts on the impeller, causing it to stop rapidly.

(f) Effects In the flow rate sensor according to the present invention, since the rotating shaft and the bearing and pivot shaft are in point contact, the rotational resistance of the impeller is small, but the minimum flow rate detection characteristics can be kept high, and when the flow stops or reverse flow occurs. Sometimes, it is also possible to improve the falling characteristics by increasing the rotational resistance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional flow rate sensor, and FIG. 2 is a sectional view of an embodiment of the flow rate sensor according to the present invention. 1: flow rate sensor, 2: main body, 3: rectifying member,
4: Rotating shaft, 5: Impeller, 6: Magnetic plate,
8: Pivot axis, 11: Magnetic sensor, 20: Channel, 44: Recess, 61: Permanent magnet.

Claims (1)

[Scope of utility model registration request] An impeller is rotatably provided in a flow path formed in the main body, and a permanent magnet is attached to a rotation shaft of the impeller so that the permanent magnet rotates together with the impeller,
In a flow rate sensor that detects the rotation of the permanent magnet using a magnetic sensor, a recess is provided at one end of the rotary shaft on the impeller side, and the rotary shaft is supported by a rectifying member attached to the main body in the recess, and is supported by a spring. The tip of the pivot shaft that was pressed to the side can be brought into contact with the pivot shaft, and the other end of the pivot shaft is made into a curved surface so that the other end can come into contact with the bearing part on the main body side, so that a backflow occurs in the flow path. A flow rate sensor characterized in that the impeller is configured to move toward the rectifying member against the elastic force of the spring and engage with the rectifying member due to a reverse rotational force acting on the impeller. .