JPS59109814A - Flow rate detector - Google Patents

Abstract

PURPOSE:To obtain a flow rate detector by which a low noise can be expected even at a high revolution of a rotor, the measuring accuracy can be improved by a stable revolution of the rotor even at a small flow speed, furthermore the installing of bearings is easily carried out, by forming the bearings of the rotor by an elastic material. CONSTITUTION:As bearings 7, 8 supporting a rotor 4 are made of an elastic material such as polyacetal resin, butadiene rubber, the vibration and noise at the revolution of the rotor 4 can be absorbed. Since the high number of revolutions of the rotor 4 per a unit flow rate can be obtained, the revolutions of the rotor 4 at the small flow speed are stabilized and an accurate measurement can be performed. Furthermore, a sufficient lubricating effect by water at the bearing parts 7, 8 can be obtd. and the durability is extended, because it can be used at the high revolutions. In particular, when the bearings 7, 8 are attached to a main body 1, the installation can be carried out easily by using elastic forces at a low cost. Thus, the prevention of noises and the improvement of measuring accuracy can be possible at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow rate detector, and more particularly to a bearing portion that provides low noise even at high rotations, stable rotor rotation even at low flow speeds, and easy installation of the bearing.

Traditionally, as noise countermeasures for flow rate detectors, for example, as seen in general household water meters, the number of rotations at maximum flow rate is kept small to prevent noise generation, or the other is to accept the high price and use the shaft. Noise was prevented by increasing the machining accuracy of the bearing and reducing the gap between the shaft and the bearing, but the former resulted in unstable rotation at low flow speeds, resulting in measurement errors, and the latter resulted in a significant increase in manufacturing costs. occured.

This invention solves the above-mentioned drawbacks, and by using an elastic member such as rubber in the bearing part, it is possible to achieve low noise even when the rotor rotates at high speed, and it also stabilizes the rotation of the rotor even at low flow speeds, improving measurement accuracy. It is an object of the present invention to provide a flow rate detector which can be easily mounted on a bearing, and whose life can be dramatically extended.

Next, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, an inlet passage 2 and an outlet passage 3 are formed in the main body 1, the axes of which are arranged perpendicular to each other, and the inlet passage 2 and the outlet passage 3 intersect with each other. A rotor 4 for detecting flow rate is provided at a portion. This rotor 4 has a spiral or turbine shape, and is arranged so that its axis coincides with the fineness of the outlet passage 3. Support shafts 5 and 6 protrude from both ends, and support shafts 5 and 6 are connected to the main body through bearings 7 and 8, respectively. It is pivoted on.

One of the bearings 7 is made of an elastic member such as polyacecool resin or butadiene rubber, and as shown in FIGS. A center '37a having a blind hole into which the tip of the support shaft 5 enters so that fluid (for example, water) can flow out to the outside through the outlet passage 3, and this center part 1a.
It consists of a plurality of leg parts 7b extending radially from the main body 10, and the projection IC at the tip of the leg part 7b is fixed in a predetermined position by fitting into the main body 10 at four places. The other bearing 8 is also made of a similar elastic member, and as shown in FIGS. 1 and 4, it has a disk shape with a through hole 8a in the center through which the support shaft 6 passes, and its peripheral edge. Each time the protrusion 8b fits into the recess of the main body 1, it is fixed in a predetermined position. Further, 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 rotor 4 at approximately the center of its length, and the fluid to be measured injected from the inlet passage 2 is transferred to the rotor 4. To flow towards a limited area, Bo) 2
a is formed.

As shown in FIG.
and a part of the other side 4C (preferably about 1 to 20% of the drawing on the other side). Therefore, the flow of the fluid to be measured that has passed through the boat 2a is rotated in one direction under the simultaneous action of a flow velocity that rotates the rotor 4 counterclockwise with a strong force and a flow velocity that rotates the rotor 4 clockwise with a weak force. Ru.

On the other hand, a plate 12 is fixed to the main body 1 with bolts 13 between the bearing 8 and the plate 12 so as to form a closed chamber 11 that houses the permanent magnet 10 and its cover 9. A plastic cover 16 for supporting this position is fixed to the plate 12 by means of adhesive or the like. This cover 16
supports a plurality of terminals 17 (five in this example), and a Hall IC 14 and a thermistor 15 are connected to the terminals 17.
Each lead wire is connected.

Note that the reference numeral 18 indicates a filler such as epoxy resin that fills the space between the walls in the cover 15 .

The rotor 4 is rotated by the flow of the fluid to be measured toward the outlet passage 3 through the boat t-2a of the artificial passage 2 at a rotational speed proportional to the flow velocity. The 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 the Hall IC 14 facing with the plate 12 in between. Assuming that the permanent magnet 10 has a pair of N and S poles formed in its circumferential direction, the hole I
C14 generates one pulse every time the permanent magnet 10 rotates once, and this pulse is sent to the external circuit via the 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 toward the outlet passage 3, the flow rate can be detected by counting the frequency of the output pulses of the Hall IC 14. Furthermore, when the thermistor 15 is provided, it is also possible to detect the temperature of the fluid to be measured.

In addition, if the fluid to be measured flows backward from the outlet passage 3 to the inlet passage 2 for some reason, this fluid flows υIL to a position halfway in the axial direction of the rotor 4 and then leaves the rotor 4. As a result, the rotational sensitivity of the rotor 4 is significantly reduced. According to the results of the experiment, the entrance pI! When water flows from 62, the flow rate at which rotor 4 starts rotating is 1.5-e/m.
In contrast, when water was flowed in the opposite direction from the outlet passage 3, the rotation start flow rate was 3.17 m1n, and the ratio of the rotation speed to the flow rate was also reduced to about 1/4. This characteristic is useful for systems that control fluid heating means according to the output of a flow rate detector, such as a flow rate detector for controlling the flow rate of fuel gas according to the hot water output flow rate of a gas instantaneous water heater. When used, even if water backflows due to some reason, it is extremely advantageous in preventing malfunctions such as igniting the burner by mistake. Even if a small flow of water is detected, the output is a fraction of that in the forward direction, so the safety advantage is that the amount of heat generated is small and the danger is low.

In particular, since the bearings 7 and 8 that pivotally support the rotor 4 are made of an elastic material, they can absorb vibration and noise during rotation. Approximately 25 dB at several 120 Hz,
Approximately 45% under similar conditions when using polyacetal resin
dB, and is extremely effective in noise prevention. In addition, since the number of revolutions per unit flow rate can be increased in this way, rotation at low flow rates is stable and accurate measurements can be made, and since it can be used at high revolutions, sufficient water lubrication effect is provided to the bearing part, which extends the life of the bearing. extends dramatically. Furthermore, since the good abrasion resistance of rubber etc. can be utilized, the service life is extended in this respect as well, and even if there are convex parts such as knurling on the support shafts 5 and 6, assembly is possible due to the flexibility of rubber etc. When attaching the bearings 7 and 8 to the main body, the elastic force can be used to extremely easily attach them, so fewer attachment bones are required and the cost of the flowmeter can be reduced.

As described above, according to the present invention, since an elastic member such as rubber is used in the bearing part, noise can be reduced even when the rotor rotates at high speeds, and rotor rotation can be stably measured even at low flow speeds. This has extremely excellent effects such as improving accuracy, making the bearing easier to install, and dramatically extending the life of the bearing.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a flow rate detector according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of one bearing, Fig. 3 is a front view thereof, and Fig. 4 is a longitudinal sectional view of the other bearing. , FIG. 5 shows a side view of the main body. 1... Main body, 2... Inlet passage, 3... Outlet passage,
4... Rotor, 5, 6... Rotor support shaft, 7, 8
... Bearing, 10... Permanent magnet, 14... Hall I
C.

Claims (1)

[Claims] A body having an inlet passage and an outlet passage through which a fluid to be measured flows, a rotor housed inside the body and rotatably supported, and an elastic member rotatably supporting a support shaft of the rotor. a permanent magnet that rotates together with the rotor, and a Hall IC that is disposed at a position facing the permanent magnet and generates pulses with a frequency proportional to the rotational speed of the permanent magnet. vessel.