JPS6237138Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a flow rate detector that generates a pulse signal with a frequency proportional to the flow rate of a fluid to be measured.

A turbine-shaped rotor is provided in the center hole of the pipe-shaped main body so as to be rotatable about an axis common to the main shaft, and the rotation of the rotor is proportional to the flow rate of the fluid to be measured flowing through the center hole of the main body. A flow rate detector has already been proposed that detects a flow rate by utilizing a change in the magnetic relationship between a permanent magnet attached to the rotor and a Hall IC provided on the main body side. This flow rate detector has the advantages of high measurement accuracy and a constant correspondence between flow rate and rotational speed because the rotor and detection part are non-contact. It is obtained only when the axis of the heart and the chamber that houses it are correctly aligned.
If this axis alignment is incomplete, the thickness of the fluid around the permanent magnet will be uneven in the circumferential direction, and due to the viscosity of this fluid, the relationship between the flow rate and rotational speed will be affected. changes.

The object of this invention is to provide a flow rate detector in which the axial center of a permanent magnet and the axial center of a chamber housing the permanent magnet can be precisely aligned with each other by a simple means.

Next, an embodiment of this invention will be described with reference to the drawings. In FIG. 1, an inlet passage 2 and an outlet passage 3 are formed in the main body indicated by the reference numeral 1, and the axes of each are arranged to be orthogonal to each other.
A rotor 4 is provided at a portion where the inlet passage 2 and the outlet passage 3 intersect. The rotor 4 has a spiral or turbine shape, and is arranged so that its axis coincides with the axis of the outlet port 3. Support shafts 5 and 6 protrude from both ends and support bearings 7 and 8, respectively. It is pivotally supported by the main body 1 via the main body 1.

One bearing 7 is provided at the tip of the support shaft 5 so that the fluid to be measured (for example, water) that flows into the inlet passage 2 and then contacts and rotates the rotor 4 flows out through the outlet passage 3. It consists of a center part 7a which has a blind hole into which the body part 7a protrudes, and a plurality of leg parts 7b extending radially from this center part 7a.
The tip of b is fixed in a predetermined position by fitting into a recess in main body 1. Also, the other bearing 8
is a disc-shaped member having a through hole in the center through which the support shaft 6 passes, and is fixed in a predetermined position by fitting into a recess in the main body 1 at its peripheral edge.
A ring-shaped permanent magnet 10 housed in a plastic case 9 is attached to the tip of the support shaft 6.

The inlet passage 2 is provided at a position such that an extension of its axis intersects the axis of the rotor 4 at approximately the center of its length, and the fluid to be measured flowing in from the inlet passage 2 is directed to the rotor 4. A port 2a is formed to direct the flow towards a limited portion of the water.
As shown in FIG. 2, this port 2a is formed at a position where only about half of the rotor 4 can be seen when viewed from the axial direction of the inlet passage 2. The flow of measurement fluid moves to rotate the rotor 4 in one direction.

On the other hand, between the main body 1 and the bearing 8, there is a closed chamber 11 that accommodates the permanent magnet 10 and its cover 9.
The plate 12 is fixed by bolts 13 so as to form a magnetic detector 14, and a plastic case 16 for supporting a magnetic detector 14, such as a Hall IC and a thermistor 15 in a predetermined position, is attached to the plate 12 by adhesive or other means. Fixed. This case 16 supports a plurality of terminals 17 (five in this example), and each lead wire of the magnetic detector 14 and thermistor 15 is connected to the terminals 17. Note that the reference numeral 18 indicates a filler such as epoxy resin that fills the space inside the cover 15.

As shown in FIGS. 3 and 4, the plate 12 has a circular shape extending outward (in the direction away from the main body 1) to form a chamber 11 in which the permanent magnet 9 is accommodated in the state shown in FIG. A substantially square shaped metal plate formed from a metal plate such as a stainless steel plate has a bulging portion 12-1 and an annular projection 12-2 that bulges inward at the base of the bulging portion 12-1. Something,
Preferably, ribs 12-3 are formed at the center of the four sides to increase rigidity against bending, and recesses 12 are formed at both ends of each rib 12-3 to facilitate bending of the ribs 12-3. -4 is formed. The outer diameter of the annular protrusion 12-2 is selected to be equal to the diameter of the opening formed at one end of the main body 1. Therefore, after inserting the bearing 8 through this opening, the main body 1
When attaching the plate 12 to the opening, the position of the plate 12 is correctly regulated by the engagement between the periphery of the opening and the protrusion 12-2.

The rotor 4 is driven by the flow of the fluid to be measured through the port 2a of the inlet passage 2 toward the outlet passage 3.
It rotates at a rotational speed proportional to the flow velocity. A permanent magnet 10 fixed to the support shaft 6 also rotates at the same speed as the rotor 4, and this rotation is detected by a magnetic detector 14 facing the rotor 4 with a plate 12 in between. Assuming that the permanent magnet 10 has a pair of N and S poles formed in the circumferential direction, the magnetic detector 14 generates one pulse every time the permanent magnet 10 rotates once, and this pulse The signal is sent to an external circuit via terminal 17. Since the rotational speed of the rotor 4 is proportional to the flow rate of the fluid to be measured flowing from the inlet passage 2 to the outlet passage 3, the flow rate can be detected by counting the frequency of the output pulses of the magnetic detector 14. In addition, when the thermistor 15 is provided,
It is also possible to detect the temperature of the fluid to be measured.

As described above, according to this invention, the mounting position of the plate with respect to the main body is correctly regulated by the engagement between the opening on the main body side and the annular protrusion on the plate side. The axial center of the housing chamber is aligned correctly, and the relationship between flow rate and rotational speed is always constant. According to the experimental results, when a plate without protrusions was used, the flow rate detection error reached ±15%, but with this device, the detection error was only ±6.5%. was able to reduce it. Since this positioning can be performed without adding any other parts, there is no accumulation of tolerances of each part. The protrusions on the plate also serve to hold the bearing in place.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a flow rate detector according to an embodiment of this invention, Fig. 2 is a side view of its main body, Fig. 3 is a side view of the plate, and Fig. 4 is a line A-A in Fig. 3. FIG. DESCRIPTION OF SYMBOLS 1... Main body, 2... Inlet passage, 3... Outlet passage, 4... Rotor, 7, 8... Bearing, 10... Permanent magnet, 11... Chamber, 12... Plate, 12-
1...Bulge, 12-2...Protrusion, 14...Magnetic detector, 15...Thermistor, 16...Case.

Claims (1)

[Scope of utility model registration request] A main body having an inlet passage and an outlet passage arranged such that their axes are substantially perpendicular to each other, and rotating about an axis parallel to the axis of the outlet passage at an intersection of the inlet passage and the outlet passage. A freely supported rotor, a permanent magnet that rotates together with the rotor, a plate attached to the main body so as to close one end of the outlet passage, and the plate is placed in a position facing the permanent magnet with the plate in between. and a magnetic detector that generates a pulse with a frequency proportional to the rotational speed of the permanent magnet,
The plate includes a cylindrical bulge provided to form a chamber in which the permanent magnet is located, and an annular protrusion that protrudes in the opposite direction from the bulge at the base of the bulge. , and an outer edge of the protrusion engages with the opening of the main body.