JPH0687820U - Flow sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a flow sensor, a bypass passage is provided separately from the main flow passage in which the impeller exists, and a part of the fluid is caused to flow into the bypass passage at the inlet to improve flow characteristics. Improve durability. [Structure] The flow sensor 1 has a hole 21 that defines a fluid passage.
A main body 2 having a blade, an impeller 50 rotatably arranged in the hole of the main body, and a magnetic sensor 6 for detecting the rotation of the impeller 50. The hole is a central portion 21b that limits the main flow passage and a bypass portion 21c that limits the bypass flow passage.
And the impeller is arranged in the main flow path.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flow rate sensor, and more particularly, to an improvement of a flow rate sensor that measures the flow rate by detecting rotation of an impeller arranged in a fluid passage by a magnetic sensor arranged near the impeller.

[0002]

[Prior art]

 Conventionally, various flow rate sensors have been provided in which the rotation of the impeller is detected by a magnetic sensor and the flow rate of the fluid is measured thereby. An example of such a conventional flow sensor is disclosed in Japanese Patent Laid-Open No. 64-2311. As shown in FIG. 9, the conventional flow rate sensor including the flow rate sensor described in this publication uses the blades for all the fluid entering from the inlet d of the fluid passage c formed in the body b of the flow rate sensor a. It will flow in the area where the car e exists. For this reason, when the total flow rate increases, the flow rate in the region where the blade wheel exists also increases, and the impeller rotation speed increases accordingly, and the load applied to the impeller also increases. become.

Therefore, the flow sensor having such a conventional structure has a problem in durability of the impeller and also has a problem of pressure loss. Furthermore, if the flow rate range is insufficient for the required flow rate, then multiple flow rate sensors must be used, which complicates the structure.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a bypass passage separate from the main flow passage in which the impeller exists, and to partially part the fluid. The purpose of the present invention is to provide a flow sensor with improved flow characteristics and improved durability by flowing into a bypass passage.

[0005]

[Means for Solving the Problems]

 The present invention relates to a flow sensor including a main body having a hole defining a fluid passage, an impeller rotatably arranged in the hole of the main body, and a magnetic sensor for detecting the rotation of the impeller. The fluid passage is divided into a main passage and a bypass passage, and the fan wheel is arranged in the main passage. The flow rate sensor may include an impeller cartridge removably inserted into the hole, the impeller cartridge may limit the main flow path, and the impeller cartridge may have a sleeve portion and A bearing case detachably mounted in the hole may be provided, the impeller may be rotatably disposed in the bearing case, and the sleeve portion may separate the main flow passage from the bypass flow passage.

[0006]

[Action]

 In the flow rate sensor having the above structure, when fluid flows into the hole of the main body, a part of the fluid flows into the main flow passage to rotate the impeller, and the rest flows through the bypass flow passage. As the flow rate in the hole increases, so does the flow rate in the main and bypass channels. The flow rate of the fluid flowing through the main flow path is detected by detecting the rotation of the impeller with a magnetic sensor. Since the flow rate of the fluid flowing in the bypass channel increases in accordance with the increase in the flow rate of the fluid flowing in the main channel, the total flow rate flowing in the flow rate sensor can be detected by detecting the flow rate in the main channel.

[0007]

【Example】

 An embodiment of a flow sensor of the present invention will be described below with reference to the drawings. 1 to 4, a flow sensor 1 of this embodiment is shown. This flow rate sensor 1 is housed in a hollow main body 2 having a hole 21 that defines a passage for fluid, an impeller cartridge 3 inserted in the hole 21 of the main body 2, and a recess formed in the main body 2. And a magnetic sensor 6.

The hole 21 of the main body 2 includes an inlet portion 21a on the upstream side (left side in FIG. 1), a central portion 21b communicating with the inlet portion 21a and arranged at the center of the main body, and diametrically opposite sides of the central portion. It is composed of the formed bypass portion 21c. A contact portion, that is, a shoulder portion 22 is formed on the downstream side (right side in FIG. 1) of the central portion 21b. The central portion 21b of the hole 21 has a circular cross section, but the two bypass portions 21c may have any shape. A recess 26 for receiving the magnetic sensor 6 is formed at a point (upper surface in FIG. 1) on the outer periphery of the center of the main body 2. The recess 26 opens on the outer periphery of the body and extends in the radial direction, but the wall 27 blocks communication with the central portion 21b of the hole. The wall 27 should be as thin as possible. The body 2 is preferably made of synthetic resin material, for example made by injection molding.

As is apparent from FIGS. 1 to 4 and 7, the impeller cartridge 3 includes a bearing case 30 and an impeller 50 whose both ends are rotatably supported in the bearing case 30. There is. The bearing case 30 has an upstream bearing portion 31 and a downstream bearing portion 41. The upstream bearing portion 31 comprises a central boss portion 32 and a sleeve portion 33 concentric with the boss portion 32, which extend in a radial direction and are circular as can be seen from FIGS. 1, 4 and 5. They are connected to each other by fixed guide vanes 34 which are circumferentially spaced apart. The guide vanes 34 extend axially obliquely with respect to the central axis of the bearing part 31, so that the fluid passages defined by the adjacent guide vanes, bosses and sleeve parts form a spiral. A bearing hole 35 is formed at the center of the boss portion 32 and opens at the rear (right side in FIG. 1) end surface. A slit 36 having a desired length is formed on the sleeve portion 33 at diametrically opposite positions. A positioning recess 37 is formed at the end of the sleeve portion 33 opposite the boss portion. The bearing portion 31 is integrally formed of a synthetic resin material.

In FIGS. 1, 6 and 7, the downstream bearing portion 41 comprises a central boss portion 42 and a ring portion 43 concentric with the boss portion 42, which extend radially between them. And a plurality of ribs 44 that are circumferentially separated from each other and are equally spaced. A bearing hole 45 is formed at the center of the boss portion 42 and opens at the front end (left side in FIG. 1). Wide protrusions 46 are formed on the outer circumference of the ring portion 43 at diametrically opposite positions. The outer circumference of the protrusion 46 is arcuate, and the radius of curvature of the arc is the same as the radius of curvature of the inner circumference of the sleeve portion 33. A positioning protrusion 47 is further formed at the center of each protrusion 46. The positioning projection 47 is shaped so as to fit snugly into a positioning recess 37 formed at the end of the sleeve portion 33. The downstream bearing portion 41 is also integrally formed of a synthetic resin material.

As shown in FIG. 7, the impeller 50 has an impeller body 51 and a shaft 55 that is inserted in the center of the impeller body so that both ends project from the ends of the impeller body 51. is doing. On the outer circumference of the impeller body 51, a plurality of (four in this embodiment) blades 52 extending in parallel to the rotation axis and equally spaced in the circumferential direction are formed. The impeller body 51 may be formed integrally with a synthetic resin mixed with a powder magnetic material and then may be magnetized, or may be integrally formed with a synthetic resin material and a magnet may be attached to the outer peripheral edge of the rear blade 52. It may be a bonded structure.

To assemble the flow sensor 1 of this embodiment, first, the impeller cartridge 3 is assembled. In the impeller cartridge 3, first, the impeller 50 is inserted into the sleeve portion 33 of the bearing portion 31 on the upstream side of the bearing case 30 and one end (the left end in FIGS. 1 and 7) of the shaft 55 of the impeller is inserted. It is inserted into the bearing hole 35 of the bearing portion. Then, with the other end (the right end in FIGS. 1 and 7) of the shaft 55 of the impeller 50 inserted into the bearing hole 45 of the bearing portion 41 on the downstream side, the bearing portion 41 is inserted into the sleeve portion 33 of the bearing portion 31. Fit into the end (right end in FIGS. 1 and 7). At this time, the positioning protrusion 47 formed on the outer circumference of the bearing portion 41 is put into the positioning recess 37 formed at the end of the sleeve portion 33, and the downstream bearing portion 41 is removed from the upstream bearing portion 31. Position. In this state, the impeller 50 is rotatable within the bearing case 30.

Next, the impeller cartridge 3 assembled as described above is inserted into the central portion 21b of the hole 21 of the main body 2 from the left side of the main body in FIG. 1 to the rear end of the downstream bearing portion 41 (see FIG. The left end) is inserted until it abuts the shoulder portion 22 formed in the central portion 21b of the hole. At this time, as clearly shown in FIGS. 3 and 4, the sleeve portion 33 is disposed at the boundary between the central portion 21b of the hole 21 of the main body 2 and the bypass portion 21c, and the sleeve portion 33 is arranged by the sleeve portion. The main flow passage limited within the portion and the bypass flow passage limited by the bypass portion are separated from each other. After the insertion of the impeller cartridge 3 into the central portion 21b of the hole 21 of the main body is completed, the stopper ring 7 is fitted into the central portion 21b of the hole 21 to prevent the impeller cartridge from coming out of the main body. . Further, the magnetic sensor 6 which may have a known structure is inserted and fixed in the recess 26 of the main body. In this way, the assembly of the flow rate sensor 1 is completed.

In the flow rate sensor having the above configuration, when fluid flows into the inlet portion 21a of the hole 21 of the main body 2 from the left side in FIG. 1, a part of the fluid is boss portion of the bearing portion 31 on the upstream side of the impeller cartridge. It flows between 32 and the sleeve portion 33 in the main flow passage defined in the impeller cartridge, and the other portion flows in the bypass flow passage defined by the bypass portion 21c. At this time, due to the action of the guide vanes 34 of the bearing portion 31, when the fluid is separated from the rear end of the guide vanes (the right end in FIG. 1), the fluid flows spirally, that is, obliquely with respect to the central axis of the fan wheel cartridge 3. Therefore, the impeller 50 rotates by hitting the side surface of the blade 52 of the impeller 50. When the impeller 50 rotates, the outer peripheral edge 53 of the magnetized blade 52 of the impeller passes near the magnetic sensor 6 placed in the recess 26 of the main body 2 and is detected. The rotation speed of the impeller 50 increases in proportion to the flow rate of the fluid flowing in the main flow path, and the number of times the impeller blades pass by the magnetic sensor 6 in proportion to the increase in the rotation speed (per unit time). ) Increases. Further, the flow rate flowing in the bypass channel also increases in proportion to the flow rate flowing in the main channel. Therefore, the flow rate of the entire flow sensor can be detected by detecting the flow rate of the main flow path. Even if the flow rate in the main flow path and the flow rate in the bypass flow path do not increase linearly in proportion to each other, it is possible to detect the flow rate in the main flow path by detecting the flow rate in the main flow path by examining the relationship beforehand. The flow rate flowing through the whole can be detected.

The cross-sectional shape of the bypass portion is not limited to that shown in FIGS. 3 and 4, but may be the shape shown as 21c ′ in FIG. 8, or various other shapes as necessary. Can be taken. Further, in the above-described embodiment, the slit extending in the axial direction is formed in the sleeve portion of the bearing case, but the slit is not necessarily provided if the thickness of the sleeve portion is reduced so as not to interfere with the detection by the magnetic sensor. unnecessary .

In the above-described embodiment, the flow rate flowing in the flow rate sensor is divided into the flow rate flowing in the main flow path and the flow rate flowing in the bypass flow path. Therefore, even if the flow rate is large, the load applied to the impeller can be reduced, and the flow rate sensor The durability of can be improved. Moreover, since the communication between the recess 26 of the main body and the hole 21 is blocked by the wall 27, there is no fear of the fluid flowing through the hole 21 leaking to the outside, and it is not necessary to provide any means for preventing the fluid leak. Further, the number of parts is small and the assembly is easy, so that the cost can be reduced.

In the above embodiment, the guide vanes are inclined with respect to the rotation axis of the impeller, so the impeller blades are parallel to the rotation axis, but the guide vanes are parallel to the rotation axis. It may be inclined with respect to the axis of rotation. Further, the cross-sectional shape of the central portion 21b of the hole 21 of the main body 2 may be matched with the shape of the sleeve portion 33 having a slit. Further, in the above embodiment, the stopper ring is used to prevent the impeller cartridge from coming out from the inside of the main body, but the inside of the main body at the position where the stop ring is fitted is the inner periphery of the central portion 21b of the hole. A plurality of protrusions slightly protruding in the circumferential direction are formed at intervals in the circumferential direction, and the sleeve portion 33 is slightly elastically deformed so as to be inserted into the central portion 21b of the hole beyond the protrusion so that the sleeve portion 33 The edge part may be engaged with the protrusion to prevent the protrusion from coming out, or one or a plurality of protrusions slightly protruding outward in the radial direction may be formed on the outer periphery of the sleeve portion and the inside of the central portion 21b of the hole of the main body may be formed. It is also possible to form a concave portion around which the protrusion fits, and fit the sleeve portion into the central portion 21b, and then fit the protrusion into the concave portion to prevent the protrusion.

[0018]

[Effect of device]

 In the present invention, the flow rate flowing in the flow rate sensor is divided into the flow rate flowing in the main flow path and the flow rate flowing in the bypass flow path. Therefore, even if the flow rate is large, the load applied to the impeller can be reduced and the flow sensor The durability can be improved. The distance between the magnetic sensor and the magnet on the impeller side can be kept constant for each product, and detection accuracy can be improved. In addition, there is no risk of fluid leaking to the outside of the main body, and the number of parts to be formed can be reduced, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a flow sensor of the present invention.

2 is a longitudinal sectional view taken along the line II-II in FIG.

3 is a sectional view taken along the line III-III in FIG.

4 is a cross-sectional view taken along line IV-IV in FIG.

FIG. 5 is one end view of the impeller cartridge.

FIG. 6 is another end view of the impeller cartridge.

FIG. 7 is an exploded perspective view of an impeller cartridge.

FIG. 8 is a sectional view similar to FIG. 3, showing another shape of the bypass channel.

FIG. 9 is a sectional view of an example of a conventional flow sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Flow rate sensor 2 Main body 3 Impeller cartridge 6 Magnetic sensor 21 Hole 21b Central part 21c Bypass part 26 Recessed part 30 Bearing case 31 Bearing part 33 Sleeve part 34 Guide vane 36 Slit 41 Bearing part 50 Impeller 52 vane

Claims (3)

[Scope of utility model registration request] 1. A body having a hole defining a fluid passage,
In a flow rate sensor including an impeller rotatably arranged in the hole of the main body and a magnetic sensor for detecting the rotation of the impeller, the fluid passage is divided into a main flow passage and a bypass flow passage, A flow sensor in which the impeller is arranged in a road. 2. The flow sensor according to claim 1, wherein
A flow sensor comprising an impeller cartridge removably inserted in the hole, the impeller cartridge defining the main flow path. 3. The flow sensor according to claim 2, wherein
The impeller cartridge comprises a bearing case having a sleeve portion and removably mounted in the hole, the impeller is rotatably disposed in the bearing case, and the sleeve portion bypasses the main flow path. A flow sensor separated from the road.