JP2544676Y2 - Electric motor with rotation detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor with a rotation detector capable of detecting the rotation of an armature.

[0002]

2. Description of the Related Art
Among the means for detecting the rotation of the armature, a magnet for the sensor is integrally provided on the shaft of the armature, and a lead switch responsive to the NS change of the magnet for the sensor accompanying the rotation of the shaft is arranged in the circumferential direction of the magnet for the sensor. Some are configured to be installed.

However, conventionally, an electric motor with a rotation detector provided with a lead switch responsive to a magnet as described above has
For example, when this is a two-pole electric motor, as shown in FIG. 5, the lead switch 10 is disposed at a position corresponding to the circumferential edge of the main pole magnet 4 fixed to the yoke. . By the way, as shown in FIG. 6, when the lead switch is substantially parallel to the magnetic field lines of the sensor magnet and there is almost no change in the magnetic field lines, that is, at the center position of the N pole or S pole of the sensor magnet, respectively. When it reaches, the switch contact is opened and it is set to switch from ON to OFF.
Although the FF switching is performed, as described above, the lead switch 10 is disposed so as to substantially correspond to the direction of the magnetic force line of the main magnetic pole magnet 4 corresponding to the space between the adjacent main magnetic pole magnets 4. Then, when the N pole of the sensor magnet 7 is located at the N pole side main pole magnet 4 position, and conversely, when the S pole of the sensor magnet 7 is located at the S pole side main pole magnet 4 position, In the former case, the magnetic field of the sensor magnet 7 is increased by the influence of the magnetic field between the NS main pole magnets 4 and is demagnetized in the latter case. For this reason, there is a problem that the ON time and the OFF time of the reed switch, which occur twice each time the core shaft makes one rotation, vary in length, so that an imbalance occurs in the ON-OFF duty ratio.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made in order to provide an electric motor with a rotation detector which can eliminate these disadvantages. A sensor magnet is integrally provided on a shaft of an armature, which is rotatably provided on a yoke on which a required number of main pole magnets are integrally attached, and the rotation of the shaft is detected in response to the sensor magnet. In an electric motor with a rotation detector, in which a lead switch is disposed so as to face a circumferential position of a sensor magnet, the position of the lead switch is set to a value in a circumferential direction of any one of the main magnetic pole magnets. It is characterized in that it is set to be a position substantially corresponding to the center line position. Further, in the electric motor with the rotation detector, the arrangement position of the reed switch is set so as to be substantially perpendicular to the direction of the line of magnetic force of the main magnetic pole magnet. .

According to the present invention, the magnetic field of the sensor magnet is prevented from being increased or demagnetized by the interference of the magnetic field of the main pole magnet.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a casing of a two-pole electric motor, and the casing 1 has a shaft 2 of an armature 2 attached thereto.
a is rotatably supported via a bearing 3. A pair of main magnetic pole magnets 4 are provided on the inner peripheral surface of the casing 1.
Are integrated. On the other hand, a rotor core 5 facing the main magnetic pole magnet 4, a commutator 6 for driving a motor, and a sensor magnet 7 described later are integrally incorporated into the shaft 2a. 8, the commutator 6
A conventional device includes a pair of brushes 9 that are slidably contacted with each other, and a lead switch 10 that switches on and off in response to the sensor magnet 7 as described later. is there.

The brush holder 8a formed on the brush holder stay 8 for accommodating the brush 9 is disposed symmetrically with respect to the axis of the shaft 2a as a base line. It is arranged symmetrically so that the position is the same. On the other hand, the lead switch 10 is disposed so as to oppose the circumferential position of the sensor magnet 7, and the position thereof is one of the pair of main magnetic pole magnets 4, in the embodiment, the N pole. Position substantially corresponding to the center line position in the circumferential direction of the side main magnet 4, that is, the direction of the magnetic force line of the main pole magnet 4, which is substantially parallel to the circumferential direction with respect to the N pole side main magnetic pole magnet 4. In other words, when viewed from the direction of the axis of the shaft 2a, in a direction around the axis, N
It is set to be located at a position substantially parallel to the pole-side main magnetic pole magnet 4.

In the embodiment of the present invention configured as described above, the process of switching ON / OFF the reed switch 10 when the shaft 2a rotates by applying power for driving the motor will be described with reference to FIG. In the drawing, for convenience of explanation, there is a main pole magnet 4 having an S pole on the left side and an N pole on the right side, and the lead switch 10 is disposed in parallel with the N pole side main pole magnet 4 and further has a sensor pole. Magnet 7
Is set to have an N pole and an S pole every 180 degrees.

FIG. 3 shows a case where the shaft 2a is rotated by 90 degrees at a time.
When switching from N to OFF, that is, the sensor magnet 7
When the N pole changes from the intermediate position between the NS pole side main magnetic pole magnets 4 to the overlapping position (when changing from A to B in FIG. 3 and changing from C to D). The magnetic field of the sensor magnet 7 is equally affected by the magnetic field of the main pole magnet 4 (of course,
The same applies to the reverse switching). As a result, O generated for two cycles during one rotation of the shaft 2a.
When the duty ratio of the N-OFF switching becomes the same, the non-uniformity does not occur as in the related art, and a highly accurate rotation detection can be obtained.

[0010]

In summary, since the present invention is constructed as described above, the reed switch performs ON / OFF switching in response to the rotation of the sensor magnet accompanying the rotation of the shaft. In that case, the reed switch is located at a position substantially corresponding to the circumferential center line position of any one of the main magnetic pole magnets, in other words, at a position substantially orthogonal to the magnetic force line direction of the main magnetic pole magnet. Therefore, the influence of the magnetic field of the sensor magnet from the magnetic field of the main magnetic pole magnet is equally symmetric when the lead switch is switched from ON to OFF or from OFF to ON during one rotation of the shaft. When the duty ratio of the ON / OFF switching of the lead switch is the same, the rotation does not become non-uniform unlike the related art, and the rotation detection with high accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional front view of an electric motor.

FIG. 2 is a side view of the electric motor with a casing cut away.

FIGS. 3A, 3B, 3C, and 3D are explanatory diagrams showing a reed switch switching process.

FIG. 4 is a diagram showing an ON-OFF duty ratio of a reed switch.

FIG. 5 is a side view of an electric motor with a casing cut away in a conventional example.

FIG. 6A is an explanatory diagram showing a demagnetization state when a read switch is switched in a conventional example, and FIG.

FIG. 7 shows ON / OFF of a lead switch in a conventional example.
It is a figure showing a duty ratio.

[Explanation of symbols]

 2a axis 4 Magnet for main pole 7 Magnet for sensor 10 Lead switch

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-48-58310 (JP, A) JP-A-48-58312 (JP, A) JP-A-56-2566 (JP, A) 187567 (JP, U) Jiko 45-10099 (JP, Y1)

Claims (2)

(57) [Scope of request for utility model registration] 1. A sensor magnet is integrally provided on a shaft of an armature, which is rotatably provided on a yoke on which a main pole magnet having a required number of poles is integrally mounted, and the shaft is responsive to the sensor magnet. In an electric motor with a rotation detector, a lead switch for detecting the rotation of the main magnet is disposed so as to face the circumferential position of the sensor magnet, the position of the lead switch is changed to any one of the main pole magnets. An electric motor with a rotation detector, wherein the electric motor is set to a position substantially corresponding to the center line position in the circumferential direction. 2. A sensor magnet is integrally provided on a shaft of an armature that is rotatably provided on a yoke on which a main pole magnet having a required number of poles is integrally mounted, and the shaft is responsive to the sensor magnet. In an electric motor with a rotation detector, a lead switch for detecting rotation of the sensor is disposed so as to face a circumferential position of the sensor magnet, the position of the lead switch is set in the direction of the magnetic force line of the main magnetic pole magnet. An electric motor with a rotation detector, wherein the electric motor is set to be at a position substantially orthogonal to this.