JP2002048609A - Manufacturing method of impeller with built-in magnet for flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To insert-mold an impeller with a built-in magnet for a flowmeter, so that no magnet is displaced. SOLUTION: Related to a manufacturing method of an impeller with a built-in ring magnet for a flowmeter, a ring magnet 13 is attached to an axis part 91 of a primary molding 9 of the impeller, which is forcedly rotated by a prescribed angle around a revolution center line 3a in one direction so that the inside surface of its center hole 131 crushes four corner parts 911 of the axis part 91. As a result, the ring magnet 13 is so temporarily fitted as not to come off the axis part 91 of the primary molding 9. Since a main body part 61 is formed by insert-molding in this condition, no ring magnet 13 displaces from an end surface 901 under a dead weight nor sticks to a movable-side die by its own magnetic force. So, an impeller 6 is formed for good rotational balance as no ring magnet 13 deviates from the primary molding 9 nor rises.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring a flow rate of tap water or the like, and more particularly, to a type in which a magnetic sensor detects rotation of an impeller rotating according to a fluid flow rate. The present invention relates to a method for manufacturing a built-in magnet type impeller in a flow meter.

[0002]

2. Description of the Related Art As a flow meter for measuring a flow rate of a fluid such as tap water, an impeller of an axial flow type or the like which rotates at a speed corresponding to a passing flow rate is disposed in a fluid passage, and the rotation of the impeller is determined. A type in which a state is detected by a non-contact type magnetic sensor is known. In this type of flow meter, a ring-shaped magnet is embedded in the end of the impeller, and a rotating magnetic field generated by the magnet is detected by a detection element of a magnetic sensor disposed outside the fluid passage.

As such a flow meter, for example,
There is a flow meter as shown in FIG. FIG. 14 (a),
(B) and (c) are a longitudinal sectional view, a left side view, and a right side view showing the flow meter, respectively.

Referring to FIG. 1, the overall structure of the flow meter 1 will be described. The flow meter 1 has a cylindrical meter case 2 in which a fluid passage 3 having a circular cross section as a whole is formed. Have been. One end of the fluid passage 3 is defined as an inlet 4 and the other is defined as an outlet 5. Inside the fluid passage 3, an impeller 6 that rotates in accordance with the flow rate of the fluid flowing therethrough is coaxial with the fluid passage. A rectifier 7 is disposed at the upstream end of the impeller 6 to generate a vortex in the fluid flowing from the inlet 4 to the impeller 6 to reduce the thrust force applied to the impeller 6.

On the downstream side of the impeller 6, an inner protruding portion 8 protruding from the inner peripheral surface of the meter case 2 to the center of the fluid passage 3 is formed, and between the inner protruding portion 8 and the rectifier 7. , The impeller 6 is rotatably supported.

A shaft portion 91 projects downstream from the center of the downstream end surface of the impeller 6, and a shaft groove 10 that rotatably receives the tip of the shaft portion 91 is located upstream of the inner projecting portion 8. It is formed on the end face. On the other hand, an axial groove 11 is formed at the center of the upstream end face of the impeller 6, and a support shaft 12 formed at the center of the downstream end face of the upstream rectifier 7 is rotatable. Plugged in state. Thus, the impeller 6 is supported from both sides in a rotatable state about the central axis 3a of the fluid passage.

Since the ring-shaped magnet 13 is embedded in the downstream end of the impeller 6 at a position deviated from the rotation center line (3a), when the impeller 6 rotates, the ring-shaped magnet 13 rotates. A rotating magnetic field is generated by the ring-shaped magnet 13. This rotating magnetic field is applied to the magnetic sensor 2 mounted from the outside of the meter case 2 to the sensor housing 21 formed inside the inner protruding portion 8 formed in the meter case 2.
3 enables detection in a non-contact state.

Here, the ring-shaped magnet 13 is built in the impeller 6 and sealed with resin so as not to be affected by chemicals and the like contained in the fluid. As shown in an enlarged manner in FIG.
Then, a ring-shaped magnet 13 is mounted coaxially, and insert molding is performed in this state.

First, as shown in FIG. 16, a primary molded product 9 in which a quadrangular prism-shaped shaft portion 91 protrudes coaxially from one end surface of a cylindrical body portion 90 is formed. The tip portion of the shaft portion 91 of the primary molded product 9 has a hemispherical surface, and a shaft groove 11 is formed coaxially on the other end surface of the body portion 90.

Next, as shown in FIG. 17, a ring-shaped magnet 13 having a square center hole 131 formed at the center so as to fit in the shaft portion 91 is prepared. This ring-shaped magnet 13
Made of sintered metal such as ferrite magnet.

The main body portion 61 is formed by insert-molding the magnet 13 mounted on the shaft portion 91 of the primary molded product 9 to obtain the impeller 6 incorporating the ring-shaped magnet 13 shown in FIG. Can be.

[0012]

However, FIG.
1 with respect to the dimension A of the shaft portion 91 of the primary molded product 9 shown in FIG.
The ring-shaped magnet 13 shown in FIG. 7 is a sintered metal such as a ferrite magnet, and thus has poor dimensional accuracy.
Becomes larger by about 0.1 to 0.2 mm. For this reason, there is a problem that the ring-shaped magnet 13 is insert-molded at a position shifted from the position where the ring-shaped magnet 13 is mounted on the primary molded article 9.

That is, in the prior art, as shown in FIG.
When the ring-shaped magnet 13 is fitted to the shaft portion 91 and the clearance between the dimension A of the shaft portion 91 and the size B of the center hole 131 is large, the ring-shaped magnet 13 is It is separated from the end face 901 and inclined by its own weight.

Next, as shown in FIG. 18 (b), when the movable mold 102 is moved to the fixed mold 101 and the mold is tightened, the ring-shaped magnet 13 tilted by its own magnetic force. Affix to the movable mold 102.

In this state, as shown in FIG.
The ring-shaped magnet 13 is pressed against the primary molded product 9 by the resin pressure from the gates 103 and 104, and the main body portion 61 is insert-molded. As a result, the diameter A of the shaft portion 91
And the clearance of the dimension B of the center hole 131 appears as the eccentric dimension C. Further, even if the ring-shaped magnet 13 is pressed by the resin pressure, the ring-shaped magnet 13 is lifted from the end face 901 of the body portion 90.
The inventor has observed that it is 1 mm. Also, even if the ring-shaped magnet 13 is magnetized after insert molding, eccentricity and lifting occur similarly just because it does not stick to the movable mold 102.

When the ring-shaped magnet 13 is displaced from the mounting position of the primary molded article 9 to form the impeller 6, the flow meter 1 has a poor rotational balance of the impeller 6,
As the durability decreases, it becomes impossible to detect a minute flow rate.

In view of such problems, an object of the present invention is to provide a method of manufacturing a magnet with a built-in impeller of a flow meter, which can perform insert molding while preventing movement of a magnet mounted on a primary molded product. Is to do.

[0018]

According to the present invention, there is provided an impeller primary molding having a shape in which a shaft protrudes coaxially from an end face of an impeller body. A ring-shaped magnet is mounted coaxially, and in this state, a magnet-containing impeller is manufactured by insert-molding in this state to manufacture a magnet-containing impeller. At the time of mounting, the ring-shaped magnet is temporarily fixed so as not to come off from the shaft portion. Therefore, insert molding can be performed while preventing movement of the magnet mounted on the primary molded product.

Here, in the manufacturing method of the impeller with built-in magnet of the flow meter according to the present invention, the ring-shaped magnet mounted on the shaft is pressed while crushing a part of the outer peripheral portion of the shaft. By forcibly rotating the ring-shaped magnet about a predetermined axis by a predetermined angle, a temporarily fixed state of the ring-shaped magnet is formed.

On the other hand, the ring-shaped magnet may be temporarily fixed to the shaft by press-fitting the ring-shaped magnet in the axial direction while crushing a part of the outer peripheral portion of the shaft. it can.

In this case, a rib extending in the axial direction may be formed on the outer peripheral surface of the shaft portion, and the ring-shaped magnet may be press-fitted in the axial direction while crushing the rib.

Further, if the formation range of the rib is set to a position distant from the end face of the impeller primary molded product, the shavings of the rib that are generated when the magnet is mounted are removed from the ring-shaped magnet and the end face of the primary molded product. It is possible to prevent the magnet from floating up from the end face of the primary molded product by escaping into the space formed.

Alternatively, if the opening edges of both ends of the center hole of the ring-shaped magnet are chamfered in a tapered shape, shavings of the rib can be released to the chamfered portion of the magnet.

Next, the cross-sectional shape of the shaft portion can be elastically reduced, and the ring-shaped magnet can be temporarily fixed by the elastic return force of the shaft portion.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a magnet built-in type impeller of a flow meter according to the present invention will be described below with reference to the drawings. In this example, the present invention is applied to the manufacture of the impeller shown in FIG. Therefore, as described with reference to FIG. 15 to FIG.
The ring-shaped magnet 13 is coaxially mounted on the shaft portion 91 of the primary molded product 9 having a shape in which the shaft portion 91 protrudes coaxially from the end surface of the main body portion 61, and is manufactured by performing insert molding in this state. .

In this embodiment, first, as shown in FIGS. 1A and 1B, the ring-shaped magnet 13 is
Attach to 1. In this state, as in the conventional configuration, there is a clearance around the entire circumference between the outer peripheral surface of the shaft portion 91 and the center hole 131, so that the ring-shaped magnet 13 is attached to the end surface 901 of the body portion 90 during insert molding. It will be shifted away from it.

Next, the ring-shaped magnet 1 shown in FIG.
3 is forcibly rotated by a predetermined angle in one of the directions around the rotation center line 3a indicated by the arrow S with respect to the shaft portion 91. As a result, as shown in FIG. 2, the four corners 9 of the shaft 91 are formed by the inner peripheral surface of the center hole 131 of the ring-shaped magnet 13.
11 is crushed. Thereby, the ring-shaped magnet 13
Is press-fitted into the shaft portion 91 of the primary molded product 9, and thus is temporarily fixed so as not to come out of the shaft portion 91.

In this state, the main body 6 is formed by insert molding.
Since the ring-shaped magnet 1 is formed, the ring-shaped magnet 13 does not shift from the end face 901 by its own weight, and does not stick to the movable mold by its own magnetic force. Therefore, the impeller 6 is
Are not eccentric or raised with respect to the primary molded product 9, so that they are formed with good rotational balance.

Here, the ring-shaped magnet 13 is press-fitted while crushing a part of the outer peripheral portion of the shaft portion 91.
The ring-shaped magnet 13 may be temporarily fixed.

FIGS. 3A and 3B are a longitudinal sectional view and a right side view showing a primary molded product used in another embodiment. 4 (a), (b) and (c) respectively show
The ring-shaped magnet 13 shown in FIG. 17 is added to the primary molded product shown in FIG.
FIG. 5 is a vertical sectional view, a right side view, and an explanatory view showing a part of the right side view in an enlarged manner, showing a state in which is mounted.

As shown in FIG. 3, the primary molded article 9A has four shafts 91A extending in the mounting direction of the ring magnet 13 at the center of each side surface of the quadrangular prism at the portion where the ring magnet 13 is disposed. Is formed so as to be connected to the end surface 901 of the body portion 90.

The ring-shaped magnet 13 is attached to the shaft 91A.
4, the ring-shaped magnet 13 can be pushed in until it hits the end face 901 while shaving and crushing the upper end portions 913 of the four ribs 912, as shown in FIG. As a result, the ring-shaped magnet 13 becomes the primary molded product 9A.
Is temporarily fixed so as not to fall out of the shaft portion 91A.

Here, when the ring-shaped magnet 13 is pushed in, the shavings of the ribs are removed from the end face of the ring-shaped magnet 13 and the end face 9.
01, and the ring-shaped magnet 13 is
May rise from the In order to avoid this adverse effect, as shown in FIG. 5, as a primary molded product 9B, the end 912A of the rib 912 is attached to the end surface 901 of the body 90.
What does not extend to what is necessary is just to use. When the ring-shaped magnet 13 is pushed into the thus-formed primary molded product 9B to a position where the ring-shaped magnet 13 comes into contact with the end face 901, as shown in FIG.
A space 80 surrounded by the twelve end portions 912A and the end surface 901 is formed. By letting the shavings escape into this space 80,
The ring-shaped magnet 13 can be prevented from rising from the body 90 of the primary molded product 9B.

In order to release the shavings of the ribs 912, the opening edges of both ends of the center hole 131 of the ring-shaped magnet 13 may be tapered. As shown in FIG. 7, the ring-shaped magnet 13A has a longitudinal section in which each opening edge 132 of both ends of the center hole 131A is chamfered in a tapered shape. Ring-shaped magnet 1 configured as above
When the ribs 912 shown in FIG. 3 are pushed into a position where the ribs 912 shown in FIG. 3 extend to the body end surface 901 and hit the end surface 901, as shown in FIG. A space 81 surrounded by the opening edge 132, the rib 912, and the end face 901 is formed between 9A. By releasing the shavings into this space 81, it is possible to prevent the ring-shaped magnet 13A from floating from the body 90 of the primary molded product 9A. The ring-shaped magnet 13A is
Since each opening edge 132 of both ends of the center hole 131 is chamfered in a tapered shape, there is an advantage that the mounting direction is not limited.

Here, the forming direction, shape, and number of the ribs 912 formed on the shaft portion 90 of the primary molded product 9 are limited to those described above as long as the ring-shaped magnet 13 can be mounted and fixed. Instead, the primary molding 9C may be set appropriately as shown in FIG.
A rib 912B may be formed around a. When the ring-shaped magnet 13 shown in FIG. 17 is attached to the primary molded article 9C configured as described above, as shown in FIG. 10, the ring-shaped magnet 13 cuts and crushes the upper end 913B of the rib 912B, thereby crushing the end surface. It is pushed into the position corresponding to 901 and is fixed to the shaft portion 91C of the primary molded product 9C.

The ring-shaped magnet 1 is crushed by crushing the ribs.
3 is to be temporarily fixed, the center hole 1 of the ring-shaped magnet 13 is
31 may be changed from a square hole to a round hole. As shown in FIG. 11, when the ring-shaped magnet 13B in which the center hole 131B of the round hole is formed is attached to the primary molded product 9A shown in FIG. 3, for example, the upper end of the rib 912 is crushed, and the primary molded product 9A is crushed. Can be positioned and fixed to the shaft portion 91A.

Here, as shown in FIG. 12, the primary molded product 9D may have a structure in which a slit 914 is provided at a position off the center of the tip portion 916 of the shaft portion 91D. With this configuration, the shaft portion side plate 915 which is in a cantilever state by the slit 914 narrows toward the center side,
The cross-sectional shape can be reduced. Therefore, as shown in FIG. 13, the ring-shaped magnet 13 is
When the shaft is pushed in while reducing the cross-sectional shape of D, the shaft side plate 9
The ring-shaped magnet 13 can be temporarily fixed by the elastic return force 15.

[0038]

As described above, according to the method for manufacturing a magnet with built-in impeller of the flow meter of the present invention, insert molding can be performed while the ring-shaped magnet is temporarily fixed to the primary molded product. The mounting position of the ring-shaped magnet does not shift with respect to the molded product. Accordingly, it is possible to prevent the rotation balance of the magnet-containing impeller from being poor. Therefore, the flow meter using the magnet built-in type impeller can prevent a decrease in the durability of the impeller due to a rotational balance failure and an inability to detect a minute flow rate.

[Brief description of the drawings]

FIGS. 1A and 1B are a longitudinal sectional view and a right side view showing a state in which a ring-shaped magnet is mounted on a primary molded product of an impeller in a method of manufacturing a magnet with built-in impeller of a flow meter according to the present invention. FIG.

2 (a) and 2 (b) are a right side view showing a state where the ring-shaped magnet shown in FIG. 1 is temporarily fixed to a primary molded product, and a cross section taken along a cutting line II ′ of the right side view. FIG.

FIGS. 3A and 3B are a longitudinal sectional view and a right side view showing an impeller primary molded product used in another embodiment.

4 (a), (b) and (c) are a longitudinal sectional view, a right side view and a right side view, respectively, showing a state where a ring-shaped magnet is mounted on the impeller primary molded product shown in FIG. It is explanatory drawing which expands and shows a part of.

FIG. 5 is a longitudinal sectional view showing an impeller primary molded product used in another embodiment.

6 (a) and (b) are longitudinal sectional views showing a state where a ring-shaped magnet is attached to the impeller primary molded product shown in FIG. 5;
FIG. 4 is an explanatory diagram showing a part of a longitudinal sectional view in an enlarged manner.

FIG. 7 is a longitudinal sectional view showing a ring-shaped magnet used in another embodiment.

8 (a) and (b) are longitudinal sectional views showing a state where the ring-shaped magnet shown in FIG. 7 is mounted on the primary molded article shown in FIG. 3, and an enlarged part of the longitudinal sectional view. FIG.

FIGS. 9A and 9B are a longitudinal sectional view and a right side view showing an impeller primary molded product used in another embodiment.

10A and 10B are a longitudinal sectional view showing a state where a ring-shaped magnet is mounted on the primary molded product shown in FIG. 9 and an explanatory view showing a part of the longitudinal sectional view in an enlarged manner. is there.

FIG. 11 shows a ring-shaped magnet used in another embodiment shown in FIG.
FIG. 4 is a right side view showing a state where the device is mounted on the primary molded product shown in FIG.

12A and 12B are a longitudinal sectional view and a right side view showing an impeller primary molded product used in another embodiment.

13 (a) and (b) are a longitudinal sectional view showing a state where a ring-shaped magnet is mounted on the primary molded article shown in FIG. 12, and an explanatory view showing a part of the longitudinal sectional view in an enlarged manner. is there.

14 (a), (b) and (c) are:
It is the longitudinal section, the left view and the right view which show the example of the flow meter provided with the impeller with a built-in magnet.

15 is a longitudinal sectional view showing an impeller in the flow meter of FIG.

16 (a) and (b) are a longitudinal sectional view and a right side view showing a primary molded product constituting the impeller shown in FIG.

17 (a) and (b) are a vertical sectional view and a right side view showing a ring-shaped magnet constituting the impeller shown in FIG.

18 (a), (b) and (c) are:
It is explanatory drawing explaining the insert molding of the impeller used for the flow meter of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water meter 2 Meter case 3 Fluid passage 6 Impeller 7 Rectifier 8 Inner protrusion 9 Primary molded product 11 Shaft groove 13 Ring-shaped magnet 21 Sensor storage part 22 Magnetic sensor 23 Detecting element 61 Body part 90 Body part 91 Shaft part 131 Center Hole 132 Opening edge 901 End face 911 Corner 912 Rib

Claims (9)

[Claims] 1. A ring-shaped magnet is mounted coaxially on the shaft of a primary molded product of an impeller having a shape in which the shaft protrudes coaxially from the end face of the impeller body, and insert molding is performed in this state. In the method for manufacturing a built-in magnet type impeller of a flow meter for manufacturing a built-in magnet type impeller, when the ring-shaped magnet is mounted on the shaft portion, the ring-shaped magnet is prevented from falling out of the shaft portion. A method for manufacturing an impeller with a built-in magnet for a flow meter, the method comprising temporarily fixing the impeller. 2. The method according to claim 1, wherein the ring-shaped magnet mounted on the shaft is forcibly rotated by a predetermined angle around an axis of the shaft while crushing a part of an outer peripheral portion of the shaft. And a method for manufacturing a built-in magnet type impeller of a flow meter, wherein the ring-shaped magnet is temporarily fixed. 3. The temporarily fixed state of the ring-shaped magnet according to claim 1, wherein the ring-shaped magnet is pressed into the shaft in the axial direction while crushing a part of an outer peripheral portion of the shaft. A method for manufacturing a built-in magnet type impeller of a flow meter, characterized by forming: 4. The magnet for a flow meter according to claim 3, wherein a rib extending in the axial direction is formed on the outer peripheral surface of the shaft portion, and the ring-shaped magnet is press-fitted in the axial direction while crushing the rib. Manufacturing method of built-in impeller. 5. The impeller with a built-in magnet for a flow meter according to claim 4, wherein the formation range of the rib is set to a position distant from an end face of the primary molded product of the impeller. 6. The impeller with a built-in magnet for a flow meter according to claim 3, wherein the opening edges of both ends of the center hole of the ring-shaped magnet are chamfered in a tapered shape. 7. The flow rate according to claim 1, wherein a cross-sectional shape of the shaft is elastically reduced, and the ring-shaped magnet is temporarily fixed by an elastic return force of the shaft. Manufacturing method of impeller with built-in magnet for meter. 8. An impeller with a built-in magnet for a flow meter, which is manufactured by the method according to any one of claims 1 to 7. 9. A flow meter comprising the impeller with a built-in magnet according to claim 8.