JPH1019913A - R.p.m. detector for rotator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the measurement accuracy without increasing the fixing space or the cost by fixing a magnet to a rotator substantially similarly to the rotational orbit of the rotator and arranging a reed switch such that the magnet traverses the vicinity of the opposite ends of the reed switch thereby obtaining two signals per revolution of the rotator. SOLUTION: A magnet 25 performs a circular motion about a protrusion 12 in a space 31 similarly to a shaft 24 as a rotor 20 rotates. A reed switch 33 is fixed in a recess 32 being made immediately above while and disposed in the diametral direction of the orbit of rotation of the magnet 25 such that the contact is located substantially in the center of the orbit. Magnetic force of the magnet 25 is adjusted such that the contact of the reed switch 33 functions only when the orbit of rotation of the magnet 25 traverses the reed switch 33. Consequently, two signals can be obtained per revolution of the rotor 20. Since the contact of the reed switch is hermetically sealed in a glass tube, reliability is enhanced and the reed switch is advantageous in the view point of fixing space or cost because a working power supply and an explosion- proof shield are not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the number of rotations of a rotating body such as a rotor or a rotating shaft, and more particularly to a detection device having a high explosion-proof property.

[0002]

2. Description of the Related Art In a detector of this type, for example, as shown in FIG. 7, a magnet 3 is fixed at a position eccentric from a rotation shaft 2 of a rotating body 1, and a reed switch 4 is located at a position crossing the rotation locus of the magnet 3. There is a device for detecting the number of rotations by operating the reed switch 4. Further, there is a switch using a Hall element instead of the reed switch 4.

[0003]

As described above, if one detector is arranged on the trajectory of the rotational motion, only one ON signal is emitted per rotation of the rotating body, so that more precise measurement is required. I can not respond to. In order to perform precise measurement, it is necessary to arrange a plurality of detectors along the rotation trajectory. For example, at least two detectors are required to detect a half rotation of the rotating body.

On the other hand, a rotation detecting device using a magnet as described above is often used for a flow meter used in a flammable atmosphere because the magnet itself does not cause sparks. In particular, when a voltage of minus tens of thousands of volts is applied as in the case of electrostatic painting, detectors that require a separate power supply for operation, such as Hall elements, may malfunction and must use a strict explosion-proof shield. It is required to keep it. However, the reed switch has a structure in which only the contacts are sealed in a glass tube, has high reliability, and does not require an operating power supply. It is advantageous in terms of.

An object of the present invention is to make it possible to take out two signals from a rotating body with one reed switch by utilizing the structural characteristics of a reed switch.

[0006]

In order to solve the above-mentioned problems, in the present invention, a magnet is attached to a rotating body so as to be substantially similar to the rotating orbit of the rotating body, and the rotating orbit of the magnet is in the vicinity of both ends of the reed switch. Alternatively, the reed switch is disposed so as to cross the extension of the reed switch. Also, a plurality of reed switches can be arranged so as to cross each other.

When the magnet crosses the vicinity of both ends of the reed switch, the contacts of the reed switch are closed. Therefore, two signals can be obtained with one reed switch.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below using a rotary flow meter as an example.

As shown in FIGS. 1 to 3, the rotary flow meter includes a measuring section 10 and a measuring section 30.

[0010] The measuring section 10 includes a flow path 1 for a fluid such as a paint.
8 and 19, a measuring chamber 11, and a rotor 20 attached to the measuring chamber 11. The flow paths 18, 19 and the measuring chamber 11 are communicated by an inlet 16 and an outlet 17.

The measuring chamber 11 is a circular recess, and a projection 12 is provided at the center thereof. A guide groove 14 of the rotor 20 is formed by an annular rising portion 13 provided concentrically with the projection 12 as a center. Is formed. The outer peripheral surface 13a of the rising portion 13 and the inner peripheral surface 1 of the measuring chamber 11 are also provided.
1a, a partition wall 15 crossing the measuring chamber 11 is provided so as to isolate the inflow port 16 and the outflow port 17 from each other.

The rotor 20 has a cup shape in which the upper end of a cylindrical body 21 is closed by a disk 22. At the center of the disk 22, a mounting portion 23 of a magnet 25 projecting upward and a shaft projecting downward. 24 are provided, and a slit 26 is formed in the cylindrical body 21.

When the slit 26 is inserted into the partition wall 15 and the shaft 24 is fitted into the guide groove 14, when the outer peripheral surface of the cylindrical body 21 comes into contact with the inner peripheral surface 11a of the measuring chamber 11, as shown in FIG. At the same time, the inner peripheral surface of the cylindrical body 21 is
The rotor 20 is accommodated in the measuring chamber 11 in a state in which the rotor 20 is in contact with the outer peripheral surface 13a of the measuring chamber 11.

The rotor 20 accommodated in the weighing chamber 11 in this manner holds the aforementioned
6 slides along the partition wall 15 while the shaft 24
It moves in a circular orbit inside and swings like rolling. Along with this, the magnet 25 also makes a circular motion about the projection 12 as with the shaft 24.

The measuring section 30 includes a mounting section 23 for the magnet 25.
A recess 32 provided directly above a space 31 in which a circular motion is made
And the reed switch 3 mounted in the recess 32
3 Lead wires at both ends of the reed switch 33 are connected to terminals 34a and 34b.
Screws 35a and 35b for connecting covered conductors 36a and 36b for taking out signals to the outside are screw-engaged with a and 34b.

As shown in FIG. 4A, the reed switch 33 is arranged so that the rotational path A of the magnet 25 is diametrical in the radial direction.
The contact point 33a is arranged so as to be located substantially at the center of the locus A. Then, the magnetic force of the magnet 25 is adjusted so that the contact point 33a operates only when the rotation locus A of the magnet 25 crosses the reed switch 33. Therefore, depending on the magnetic force of the magnet 25, the reed switch 33 may be arranged inside the trajectory A in the diameter direction of the trajectory A as shown in FIG. If the intervals between the ON signals need not be uniform, it is not necessary to make the contact point 33a coincide with the center of rotation.

As shown in FIG. 5, if two reed switches 33 are arranged in a cross, four on signals can be obtained by one rotation of the magnet 25. In this case, the failure of the other reed switch can be detected based on the interval (pulse interval) of the ON signal.

As shown in FIG. 6, a magnet 25 is fixed at a position distant from a rotation center 42 of a shaft 41 supported and rotated by a bearing 40, and a reed switch 33 is mounted on the front surface of the magnet 25 by the magnet 25. If it is arranged to operate twice in rotation, the number of rotations of the shaft 41 can be detected.

The magnet 25 (and thus the rotating body on which the magnet is mounted) is not necessarily limited to a circular orbit. The present invention can also be applied to the case of drawing an elliptical orbit, an elliptical orbit, and other irregular orbits. In the case of drawing an irregular track, for example, there is an endless belt supported by a plurality of pulleys.
In this case, the magnet may be attached to the side edge of the belt.

[0020]

EXAMPLE A non-magnetic block (16.times.50.times.50 mm) of a measuring section 30 as shown in FIG. 1 was prepared. Circular space 3
1 has a diameter of 14 mm, a depth of 3 mm, and a circular recess 32.
Had a diameter of 30 mm and a depth of 12 mm. Circular recess 3
A commercially available reed switch having a length of 19 mm and a diameter of 3 mm is fixed to the bottom of the base 2 with an adhesive so that the contact point substantially coincides with the center of the circular recess 32, and a pulse counter circuit is mounted on the lead wires at both ends. Connected.

On the other hand, a magnet 25 having a diameter of 4 mm is inserted and fixed in a mounting portion 23 having a height of 4 mm, an outer diameter of 6 mm, and an inner diameter of 4 mm provided at the center of a cup-shaped rotor 20 having a diameter (outer diameter) of 27 mm. Was rotated 10 times / second while making contact with the inner periphery of the circular space 31, and a pulse of 20 times / second was obtained.

[0022]

According to the present invention, as described above, the magnet is attached to the rotating body so as to be substantially similar to the rotation trajectory of the rotating body.
Since the reed switch is arranged so that this magnet crosses the vicinity of both ends of the reed switch, two signals can be obtained for one rotation of the rotating body, the measurement accuracy is improved, and the mounting space and cost are different from the conventional one. Absent.

Further, by mounting a plurality of reed switches crossing each other, more signals can be generated, and the failure of the other reed switch can be detected.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a rotary flow meter showing an embodiment according to the present invention.

FIG. 2 is a plan view showing a measuring unit according to the first embodiment;

FIG. 3 is a cross-sectional view of the measuring unit according to the first embodiment;

FIG. 4 is a plan view showing an arrangement of a reed switch.

FIG. 5 is a plan view showing another example of the arrangement of the reed switches.

FIG. 6 is a side view showing another example of the detection device.

FIG. 7 is a front view showing an example of a conventional detection device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rotating body 2 rotating shaft 3 magnet 4 reed switch 10 measuring section 11 measuring chamber 12 projection 13 rising section 14 guide groove 15 partition 16 inflow port 17 outflow port 18, 19 flow path 20 rotor 21 cylindrical body 22 disk 23 mounting section 24 Shaft 25 Magnet 26 Slit 30 Measurement unit 31 Space 32 Recess 33 Reed switch 33a Reed switch contact 34a, 34b Terminal 35a, 35b Screw 36a, 36b Coated wire 40 Bearing 41 Shaft 42 Rotation center A Rotation locus of magnet

Claims (2)

[Claims] 1. A rotating body in which a magnet is attached to a rotating body so as to be substantially similar to the rotating orbit of the rotating body, and the reed switch is arranged so that the rotating orbit of the magnet crosses the vicinity of both ends of the reed switch or an extension thereof. Rotation speed detection device. 2. The rotation speed detecting device for a rotating body according to claim 1, wherein the reed switches are composed of a plurality of switches and are arranged so as to cross each other.