JPH06201418A - Flow sensor - Google Patents

Abstract

PURPOSE:To provide a flow sensor of such type as an impeller is contained rotatably in a linear cylindrical body and the frequency of flux variation due to rotation of the impeller is detected by means of a detecting element mounted on the body in which detection accuracy can be enhanced while allowing downsizing of the sensor. CONSTITUTION:An impeller 2 is coupled coaxially with an integral cylindrical body 23 while coupling each blade at the tip thereof. A guide tube 13 is disposed coaxially with the impeller 2 in the vicinity thereof on the upstream side in the body 1 with the inlet diameter of the cylindrical body 23 being set equal to or larger than the outlet diameter of the guide tube 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate sensor used in a water heater or the like, and more particularly to a flow rate sensor of a type in which an impeller is rotatably housed in a sensor passage and the rotational speed of the impeller is output as a signal. It can be used for controlling the temperature of the water heater, etc.

[0002]

2. Description of the Related Art Flow sensor of the above type
As the above, the one in Jikken 3-17223 is already known. As shown in FIG. 1, this conventional one has a main body (1)
Is a cylindrical body with a linear flow path from the inlet (11) to the outlet (12), and the impeller (2) made of magnetic material is rotatably housed in the center of the main body (1). Then, the detection element (S) is opposed to the impeller (2) through the constituent wall of the main body (1), and the magnetic flux change of the magnetic body when the impeller (2) rotates by the flow, Alternatively, the magnetic flux direction and the like can be detected by the detection element.
It is detected by (S).

The impeller (2) is integrally formed of a synthetic resin material in which fine particles of a magnetic material are homogeneously dispersed, and the blades are alternately magnetized into S poles and N poles. It is a thing. The impeller (2) has a core
(L) is pivotally supported by a pair of a first bearing sleeve (15a) and a second bearing sleeve (15b) provided in the center of the flow path.

The detecting element (S) is mounted on the outer wall surface of the main body (1) so as to face the impeller (2). In the flow rate sensor having such a configuration, the main body (1)
When the flow flowing in from the inlet (11) of the impeller (2) passes through the impeller (2), the impeller (2) is rotated by pushing each blade surface of each blade of the impeller (2) in the turning direction. .

At this time, the rotation speed of the impeller (2) is proportional to the flow rate of the flow. That is, the impeller
When each blade of (2) passes the position opposite to the detection element (S), the detection element (S) outputs an output signal, and when the interval between the output signals is small, the flow rate is large and conversely large. If the flow rate is low. Therefore, the flow rate can be calculated by the number of output signals per unit time.

In the above-mentioned type, since the impeller (2) is housed in the flow path, the sensor as a whole can be downsized, and the space occupied by the sensor in the water heater can be reduced.
There is an advantage that the space becomes smaller. However, the above-mentioned type has a problem that the detection accuracy of the sensor is insufficient.

In order to improve the detection accuracy, it is necessary to make the number of output signals per unit time exactly proportional to the flow rate as described above. That is, the flow in the main body (1) and the rotation of the impeller (2) must be exactly proportional. However, in the case of the above type, the blade edge of the impeller (2) and the main body
(1) There is a considerable amount of flow passing between the walls.
Therefore, there is a flow that is not involved in the rotation of the impeller (2), and this flow rate is not converted as a signal. Therefore, an error occurs between the actual flow rate and the flow rate detected by the detection element (S), and as a result, the flow rate sensor-
As a result, the detection accuracy will decrease.

[0008]

[Technical Problem] The present invention has been made in view of the above-mentioned problems. "The impeller (2) is rotatably housed in the main body (1) having a linear tubular shape, and the impeller (2 ), The frequency of the magnetic flux change due to the rotation is detected by the detection element (S) mounted on the main body (1) '', and the detection accuracy is improved without impairing the miniaturization of the sensor. That is the technical issue.

[0009]

[Technical Means] The present invention was devised to solve the above technical problem. The "impeller (2) has its blades (22) and (22) connected to their tips and the impeller (2). A cylindrical guide tube (13) coaxial with the impeller (2) is provided in the main body (1) in the vicinity of the upstream side of the impeller (2) by continuously providing an integral cylindrical body (23) coaxial with the impeller (2). And the inlet diameter of the cylindrical body (23) is set to be equal to or larger than the outlet diameter of the guide cylinder (13) ”.

[0010]

The above technical means of the present invention operates as follows. In the main body (1), the guide cylinder (13) is located near the upstream side of the impeller (2). Therefore, the body
The flow flowing into the (1) reaches the impeller (2) via the guide tube (13). Then, the blade (2) of the impeller (2)
2) Since the cylindrical body (23) provided on the outer periphery of (22) has an inlet diameter equal to or larger than the outlet diameter of the guide cylinder (13), the guide cylinder (13)
Almost all of the flow from the flow will flow into the cylindrical body (23) and pass through the blade (22) (22) (22) installation part of the impeller (2). Exactly proportional to the speed of the car (2).

[0011]

[Effects] The present invention having the above-described structure has the following unique effects. Since the flow rate in the main body (1) and the rotation speed of the impeller (2) are accurately proportional, the signal output frequency of the detection element (S) and the flow rate are accurately proportional, and the detection accuracy is improved.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. In this embodiment, the inlet (1
An impeller (2) equipped with a magnetic material is rotatably housed in a linear tubular body (1) from the (1) to the outlet (12), and a detection element ( S) The present invention is applied to a flow sensor of a type in which (MR sensor) is opposed.

A cylindrical body (23) is externally fitted and integrated with the impeller (2) so as to connect the leading edges of the blades (22) and (22).
In order to simplify the integration of the two, a method of fitting and fixing the impeller (2) in the cylindrical body (23) is adopted. Therefore, as shown in FIG. 3, the impeller (2) includes a plurality of plate-shaped blades (2) radially extending from a shaft portion (21) having a metal core (L).
2) A locking ring (24) that joins the front edge groups of (22) is provided. The locking ring (24) is located at the axial end of the impeller (2), and the locking claw (2
5) (25) is projected. On the other hand, as shown in FIG. 4, an enlarged diameter portion (26) of a size to just fit the locking ring (24) is provided on the inner peripheral surface of the downstream side of the cylindrical body (23). The part (26) is provided with rectangular openings (27) and (27) corresponding to the locking claws (25) and (25).

Then, the locking ring (24) is fitted into the enlarged diameter portion (26) of the cylindrical body (23) so that the entire impeller (2) is housed in the cylindrical body (23). The locking claws (25) (25) are
7) Fitted in (27), the cylindrical body (23) engages with the locking ring (24) in a retaining state, and is integrated with the impeller (2). As shown in FIG. 2, the impeller (2) having the above construction is rotatably incorporated in a cylindrical impeller case (4) which is fitted and fixed in the middle of the main body (1). The feather case
The downstream end of (4) becomes a small diameter cylinder part (41), and the second bearing cylinder (15b) provided at the center of the small diameter cylinder part (41) is formed by a plurality of supporting vanes (F) (F). It is fixed in series. Inside the second bush (15b), there is a ceramic bearing (1
5c) is installed. A guide tube at the other upstream open end
(13) is fitted into the guide tube (13).
Similar to the bearing tube (15b), a first bearing tube (15a) is provided and is integrated with the guide tube (13) via a plurality of supporting vanes (F) (F).

Therefore, an impeller in which the guide tube (13) is integrally attached to the cylindrical body (23) without being inserted into the blade case (4).
Insert the downstream protruding end of the core body (L) of (2) into the second bearing tube (15b), and then insert the other protruding end of the core body (L) into the first bearing tube (1).
5a) Insert the guide tube (13) into the blade case (4).
Of the impeller (2) when fitted into the open end of the
It is rotatably installed in the sleeve (4).

The downstream end of the first bearing sleeve (15a) and the upstream end of the second bearing sleeve (15b), that is, a ceramic bearing.
The distance from (15c) is set longer than the length of the shaft portion (21) of the impeller (2), and the impeller (2) is movable in a certain range in the axial direction. Also, the first bearing tube (15a) and the shaft portion (21)
Both of the contact end faces of the saw-toothed portion are saw-toothed portions as shown in FIG. 5, and the one-way clutch mechanism is constituted by the pair of saw-toothed portions, and the first bearing cylinder (15a) and the shaft portion (21 ), The impeller (2) is prevented from reversing.

The assembly of the impeller (2) and the impeller case (4) described above is inserted from the upstream side of the main body (1), and as shown in FIG.
When the small-diameter cylindrical portion (41) is fitted into and abuts the corresponding small-diameter stepped portion (1a) and is fixed in the retaining state by the retaining ring, the cylindrical body (23)
The middle part of the body and the detection element (S) outside the body (1) face each other.
On the outer peripheral surface of the cylindrical body (23), as shown in FIG. 4, strip-shaped ferromagnetic bodies (P) (P) projecting parallel to the axis are juxtaposed at a predetermined pitch. The polar directions of the ferromagnetic bodies (P) and (P) are alternately opposite in the radial direction of the cylindrical body (23).

Therefore, when the impeller (2) rotates in proportion to the flow in the main body (1), the detection element (S) detects a change in the magnetic flux direction of the ferromagnetic bodies (P) (P) and outputs a signal. Output. In addition, ferromagnetic
By making (P) (P) into a band shape, the outer peripheral surface other than this part becomes concave and becomes a relief area for foreign matter, and foreign matter remains attached to the tip of the ferromagnetic material (P) (P) It prevents it from being detected.

In this embodiment, since the diameter of the downstream end outlet of the guide cylinder (13) is slightly smaller than that of the upstream end inlet of the cylindrical body (23), the flow passing through the guide cylinder (13) That is, all of the flow in the main body (1) flows in the cylindrical body (23), and the above-described action can be obtained. Further, in this embodiment, a one-way clutch mechanism is formed between the shaft portion (21) and the first bearing tube (15a), but in the case of normal flow,
Since the shaft part (21) is moved in the axial direction by a certain range and the pair of saw tooth-shaped parts forming the one-way clutch mechanism are separated from each other, the impeller (2) rotates smoothly.

On the other hand, when water hammer pressure occurs due to a sudden blockage of the pipe line downstream of the flow rate sensor, the impeller (2)
Is pushed to the upstream side, and the shaft portion (21) becomes the first bearing tube (15a).
To face. Further, although a reverse rotation torque acts on the impeller (2), as described above, the shaft portion (21) and the first bearing tube (15a) are engaged in the reverse rotation prevention state, so that the impeller ( 2) does not rotate in the reverse direction.

Therefore, no malfunction occurs in which the detection element (S) detects the water hammer pressure as a flow rate. Further, in the above-mentioned conventional technology, the impeller (2) is of a type in which fine particles of a magnetic material are uniformly dispersed, but in this type, the magnetic poles are formed by the impeller itself. Therefore, the number of magnetic poles matches the number of blades, but in the present embodiment, as described above,
(P) and (P) are provided on the outer peripheral surface of the cylindrical body (23) and can be provided in a number equal to or larger than the number of blades.

With this configuration, a large number of signals corresponding to the number of magnetic poles can be output, so that the detection operation of the detection element (S) becomes quick and reliable. In this embodiment, the MR sensor is used as the detecting element (S), but the Hall IC
May be used. Blades (22) for forming the impeller (2)
The cylindrical body (23) may be integrated. Also, the guide tube (13) is the main body
It may be integrated with (1) or with the blade case (4).

Further, as shown in FIG. 6, the downstream end portion of the guide cylinder (13) may enter into the cylindrical body (23).

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a conventional flow sensor.

FIG. 2 is a sectional view of a main part of a flow sensor according to the present invention.

FIG. 3 is an explanatory view of the impeller (2), (a) is a side view thereof, and (b) is a plan view thereof.

FIG. 4 is a perspective view of a cylindrical body (23).

FIG. 5 is a side view of a main part of the one-way engagement mechanism.

FIG. 6 is a cross-sectional view of essential parts showing another configuration of the cylindrical body (23) and the guide tube (13).

[Explanation of symbols]

 (1) ・ ・ ・ Main body (2) ・ ・ ・ Impeller (23) ・ ・ ・ Cylindrical body (13) ・ ・ ・ Guide tube (S) ・ ・ ・ Detection element

Claims (1)

[Claims] 1. An impeller (2) is rotatably housed in a linear cylindrical main body (1), and the frequency of magnetic flux change due to rotation of the impeller (2) is attached to the main body (1). In the flow sensor of the type that detects with the detecting element (S), the impeller (2) is connected to the tip of each blade (22) (22) and is coaxial with the impeller (2). A cylindrical guide tube (13) coaxial with the impeller (2) is located in the main body (1) near the upstream side of the impeller (2). A flow sensor in which the inlet diameter of the cylindrical body (23) is set to be equal to or larger than the outlet diameter of the guide cylinder (13).