JPS5844375Y2 - Motor rotation speed detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotational speed detection device for detecting the rotational speed of a motor having an annular magnetic rotor and a stator including a coil and a core that provide rotational force to the rotor.

There is a device that uses magnetic means as a means for detecting the rotational speed of the above-mentioned motor.

In such a device, a conductor is disposed opposite to a rotor consisting of an annular magnet magnetized with multiple poles in the circumferential direction so that the magnetic flux that moves as the rotor rotates crosses the conductor. The rotational speed is detected by the generated voltage.

In the method, it is necessary to increase the relative position accuracy between the conductor and the magnet in order to increase the speed detection sensitivity, and the accuracy of each component is also required to be extremely strict.

If these requirements are not met, a decrease in detection sensitivity is unavoidable, resulting in the need for a highly sensitive detection circuit in the control circuit section, resulting in an increased cost.

An object of the present invention is to provide a highly sensitive motor rotation speed detection device.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a sectional view of a motor to which a rotation detection device according to an embodiment of the present invention is added.

A rotating shaft 3 is supported by a thrust bearing 2 on a base indicated by reference numeral 1, and a magnet holder 4 is additionally attached to this rotating shaft 3.

A pair of annular magnets 5 and 6 are attached to the magnet holder 4, which are arranged concentrically around the rotating shaft 3 as shown in the figure.

A core and a coil 7 fixedly attached to the base 1 are arranged in the gap formed by the pair of magnets 5 and 6.

The annular magnets 5 and 6 are each magnetized so that a predetermined number (same number) of magnetic poles are lined up along the circumferential direction, and one end surface (lower end surface in this example) of each of the annular magnets 5 and 6 is magnetized so that a predetermined number (same number) of magnetic poles are arranged in the circumferential direction. A large number of magnetic poles of the same number are lined up and magnetized.

That is, each of these magnets 5 and 6 has two types of magnetic pole arrays: a predetermined same number of magnetic poles located on the circumferential surfaces facing each other, and a large number of the same number of magnetic poles located on the lower end surface, and the former magnetic pole is The interaction between the magnetic flux and the current flowing through the coil 7 causes the rotor, which is the magnets 5 and 6, to rotate.

The latter one is used for detecting the rotational speed of the rotor, which will be described later.

Incidentally, a motor used as a pair of annular magnetic rotors as shown in FIG. 1 is well known.

In FIG. 3, the arrangement of the above-mentioned rotational speed detection magnetic pole arrays is shown with a reduced number for convenience.

Referring again to FIG. 1, the base 1 has a magnet 5.
and a substrate 8 disposed opposite the magnetized lower end surface of 6.
has been added.

A series of conductors 9 and 9' are printed on this substrate 8, as shown in FIG.

The conductors 9 and 9' face the magnetic pole arrays for speed l detection of the magnets 5 and 6, respectively, and if only one conductor 9 is described in detail, they extend in the radial direction at a plurality of locations, in other words, The magnetic flux generated from the detecting magnetic pole array of the rotating magnet 5 is provided in a zigzag shape so as to interlink with and cross a part of the conductor 9.

Also, the relative position between the N and S poles of the magnet 5 and the radially extending portion of the conductor 9 is determined so that the currents induced in the radially extending portion of the conductor 9 do not cancel each other out. Define the relationship.

For example, when one of the radially extending portions of the conductor 9 faces the N pole of the magnet 5, the portions on both sides thereof are arranged to face the S poles on both sides of the N pole of the magnet 5. .

The other conductor 9' is also arranged in exactly the same relationship as the conductor 9.

Then, conductors 9 and 9' are connected in series.

That is, the configuration is such that the starting point 10 of the conductor 9 is connected to the starting point of the conductor 9, and the ending point 11 of the conductor 9' is the overall ending point 11, and between the points 10 and 11,
A rotational speed detection signal will be derived.

In this configuration, magnets 5 and 6 which are rotors
When the magnetic pole array rotates, the magnetic flux generated from each magnetic pole array interlinks and traverses the conductors 9 and 9', respectively, so that a voltage is generated across each of the conductors 9 and 9'.

It is clear that in this case, since the conductors 9 and 9' are connected in series, a voltage equal to that of the side conductors is generated at both ends 10 and 11.

And the frequency of this voltage is determined by the change in polarity of the magnetic flux crossing the conductors 9, 9' within a unit time, that is, the change in the polarity of the magnetic flux across the conductors 9, 9'.
Since the frequency is proportional to the rotation speed of the motor, the rotation speed of the motor can be detected from the frequency.

However, since the phases of the signals generated in the side conductors 9 and 9' must be equal, as shown in FIG. In addition, in order to achieve high sensitivity, these opposing adjacent magnetic poles have the same polarity.

As detailed above, according to the present invention, in a motor using a pair of annular magnets as a rotor, a speed detection device is added to each magnet, and the outputs of these detection devices are connected in series with each other to increase the speed. As a result, the output of the entire detection device increases, and therefore the sensitivity of the speed detection device can be improved.

Therefore, there is no need to increase the mounting precision between the conductors 9, 9' and the magnets 5, 6, or the precision of each component compared to the past, and there is no need to configure the sensor detection circuit with high sensitivity. be.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a motor to which an embodiment of the present invention is applied, Fig. 2 is a schematic diagram of a speed detection magnetic pole array of the present invention, and Fig. 3 is a schematic diagram of a conductor for generating a speed detection signal of the present invention. . Explanation of the symbols of the main parts: 5, 6...Annular magnet, 7...Coil, 8...Printed circuit board, 9°9'...Conductor.

Claims (2)

[Scope of utility model registration request] (1) First and second annular magnets arranged concentrically with each other and a coil provided between the first and second magnets to provide rotational force to the magnets are used as a rotor and a stator, respectively. A rotational speed detection device for a motor having a plurality of poles magnetized in the circumferential direction on one end surface of each of the first and second magnets, and adjacent to the magnetized poles and the magnetic poles of the first magnet. first and second speed detection magnetic pole arrays configured such that the magnetized poles of the second magnet exist within the same angle from the motor rotation center; A first conductor and a second conductor are fixed at positions facing the magnetic pole array and interlink with magnetic fluxes from the first and second magnetic pole arrays, respectively, and the first and second conductors are connected in series. A motor rotation speed detection device characterized by: (2) The motor rotational speed detection device according to claim 1, wherein the first and second conductors are printed and wired on a printed circuit board.