JP4863474B2 - Motor with built-in rotation sensor with electromagnetic brake - Google Patents

Description

  The present invention relates to a motor with an electromagnetic brake incorporating a rotation sensor.

A conventionally known technique is a motor having an electromagnetic brake.
In a motor equipped with this electromagnetic brake, the brake yoke is magnetized when the power is turned on, the armature is attracted to the brake yoke by its magnetic attractive force, and the brake is released by creating a gap between the friction plate and the armature, The motor shaft rotates. On the other hand, when the current is cut off, the magnetic attraction force of the brake yoke disappears, and the armature is pushed back by the force of the torque spring to apply a braking force to the friction plate and stop the motor shaft.

  By the way, in a motor equipped with this electromagnetic brake, leakage magnetic flux is generated from a brake yoke or motor shaft that has caused magnetic saturation. Therefore, this motor has a rotation sensor for detecting the rotational speed and direction of the motor shaft. In such a case, there is a possibility that the detection accuracy of the rotation sensor may be lowered or the rotation sensor may malfunction due to the magnetic effect of the leakage magnetic flux.

  As a means for preventing or reducing the magnetic influence of the leakage magnetic flux, it is conceivable to install a rotation sensor at a position where the magnetic influence does not reach, but depending on the installation position of the rotation sensor, the structure of the entire motor including the rotation sensor There is a problem that is too large.

Therefore, in a motor having an electromagnetic brake, for example, as disclosed in Japanese Patent Laid-Open No. 2001-238426, a magnetic shield plate is provided between the motor and the rotation sensor, so that the magnetic influence of the leakage magnetic flux on the rotation sensor is reduced. There is technology to prevent and reduce.
FIG. 6 is a cross-sectional view of a main part of a motor including the rotation sensor 82 disclosed in Japanese Patent Laid-Open No. 2001-238426. In this technology, as shown in FIG. 6, a magnetic shield plate 84 is installed between the stator winding 80 that generates a leakage magnetic flux and the rotation sensor 82, thereby preventing the magnetic influence of the leakage magnetic flux on the rotation sensor 82. -Try to reduce.
JP 2001-238426 A

FIG. 7 (a) is a partial longitudinal sectional view showing the structure of the entire motor disclosed in Japanese Patent Laid-Open No. 2005-124259, and FIG. 7 (b) is an enlarged sectional view of the main part of the motor.
As shown in FIG. 7, the technique disclosed in Japanese Patent Application Laid-Open No. 2005-124259 is provided with a rotation sensor 90 installed at an end portion of a motor shaft 92 protruding to the opposite side of the motor, and the rotation sensor 90 and a brake yoke. The magnetic shield plate 96 made of a magnetic material is installed between the magnetic sensor 94 and the magnetic sensor to prevent or reduce the magnetic influence of the leakage magnetic flux on the rotation sensor 90.
JP 2005-124259 A

  However, in the technique disclosed in Patent Document 1, since the rotation sensor 82 is installed outside the motor case 86, when the motor is used outdoors, the rotation sensor, which is a precision instrument, is used as rainwater or Since it is necessary to take measures to protect from dust and the like, there is a problem that costs increase. In addition, since the rotation sensor 82 is installed outside the motor case 86, it is difficult to make the entire motor compact, and the rotation sensor 82 is installed at the end of the product. It is easily affected by impacts, etc., and must be handled with care.

Also, in the technique disclosed in Patent Document 2, the rotation sensor 90 is installed outside the motor case 98. Therefore, when used outdoors, the rotation sensor 90 needs to be waterproofed or dustproof. The fan cover 102 also needs to be enlarged to cover the rotation sensor, and the cost increases accordingly.
On the other hand, in order to protect the rotation sensor 90 from rainwater and dust by providing the fan cover 102 with a fully closed structure instead of waterproofing / dustproofing the rotation sensor 90, air from the outside of the fan cover 102 is used. This causes a problem that the motor cooling effect is not exhibited by the fan 100.

  In view of the problems of the prior art as described above, the present invention prevents the magnetic influence on the rotation sensor due to the magnetic flux leaked from the electromagnetic brake and the motor shaft magnetized by the electromagnetic brake, and is further sealed. An object of the present invention is to provide a motor with a built-in rotation sensor with an electromagnetic brake that is not limited in its use environment and has excellent shock resistance by incorporating a rotation sensor in the motor case.

The present invention relates to a rotation sensor built-in motor having a magnetic shaft and an electromagnetic brake.
The rotation sensor is composed of a magnet, a Hall element, and a Hall element installation substrate, and the mounting base of the rotation sensor is composed of a nonmagnetic material,
The motor includes a motor rotor and a fan, and a magnetic shield plate made of a magnetic material through a gap between a back surface of a brake yoke of the electromagnetic brake and a rotation sensor includes the magnet, the hall element, and the hall element installation substrate. It is provided in a range that covers in the radial direction ,
The motor rotor, rotation sensor, magnetic shield plate, air gap, electromagnetic brake, and fan are arranged in this order from the motor rotor to the fan.

According to the present invention, since the magnetic influence on the rotation sensor due to the magnetic flux leaked from the motor shaft magnetized by the magnetic brake and the electromagnetic brake is prevented / reduced, the detection accuracy of the rotation sensor is reduced or the rotation sensor is The risk of malfunctions can be reduced.
In addition, since the magnetic influence on the rotation sensor is prevented / reduced, the distance between the electromagnetic brake and the rotation sensor can be shortened, whereby the total motor length can be reduced.
Further, if the rotation sensor is built in the motor case which is a strong and hermetically sealed structure, the impact resistance is improved and the use environment is not affected. And since the fan cover is sufficient to cover only the fan, a large fan cover is not required and costs can be reduced. Even when used outdoors, the fan cover does not need to be fully closed. The cooling effect of the motor is also demonstrated.
Further, unlike the case where the rotation sensor is provided at the end portion of the motor shaft, since the rotation sensor is built in the motor case, it is possible to attach a manual shaft, which is often used in an electromagnetic brake motor, to the end of the motor shaft.

The first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a longitudinal sectional view of a rotation sensor built-in motor with an electromagnetic brake according to a first embodiment of the present invention along a rotation axis, and is a view of an internal structure as viewed from the side.
FIG. 2 is an enlarged cross-sectional view of the vicinity of the rotation sensor according to the first embodiment of the present invention.
FIG. 3 shows the state of leakage magnetic flux from the brake yoke and the motor shaft of the rotation sensor built-in motor with electromagnetic brake according to the first embodiment of the present invention, and FIG. FIG. 3B is a diagram when the shield plate is not installed, and FIG. 3B is a diagram when the magnetic shield plate of the first embodiment of the present invention is installed.

  In FIG. 1, a rotation sensor built-in motor 10 with electromagnetic brake (hereinafter simply referred to as “motor 10”) is provided with a well-known motor structure in a motor case 12, and a motor shaft 14 is provided at the center. Yes. The motor 10 is a general-purpose motor that does not require the use of a controller.

The motor shaft 14 is a magnetic shaft that is magnetized by the electromagnetic brake 20, and is rotatably supported by the bearing 16 on the non -load side.
The brake yoke 20a and the electromagnetic coil 20b constituting the electromagnetic brake 20 are installed at the radially outer end of the anti-load side bracket 18 so as to constitute a part of the anti-load side bracket 18.
The armature 20c also constitutes the electromagnetic brake 20, and is installed adjacent to the fan 50 side of the brake yoke 20a.
When the power is turned on and the brake yoke 20a is energized, the armature 20c is attracted to the brake yoke 20a, a gap is formed between the friction plate 20d, the electromagnetic brake 20 is released, and the motor shaft 14 rotates. In this excited state, leakage magnetic flux is generated from the brake yoke 20a and the magnetized motor shaft 14.

Next, the mounting base of the rotation sensor 40 in the present invention will be described.
The rotation sensor 40 includes a ferrite magnet 34 (hereinafter simply referred to as “magnet 34”), a magnet mounting base 30a, a Hall element 36, a Hall element mounting substrate 38, and a Hall element mounting base 30b. The mounting bases 30a and 30b are made of a nonmagnetic material such as an aluminum material so as not to be magnetized by magnetism.
When an aluminum material is used as the material for these mounting bases, the weight and the inertia can be reduced, and the heat radiation can be increased, so that the influence of heat on the magnet 34 and the Hall element 36 can be reduced. Can be suppressed.
Hereinafter, the configuration of the magnet mounting base 30a and the hall element mounting base 30b will be described.

The disc-shaped magnet mounting base 30 a is mounted on the motor shaft 14 between the anti-load side bearing 16 and the rotor fin 28 so as to rotate as the motor shaft 14 rotates.
The magnet mounting base 30a has a ring-shaped magnet 34 in which N and S poles are alternately magnetized.

  A positioning projection 32 is provided at the outer end of the magnet mounting base 30a in the radial direction. The positioning protrusion 32 is in contact with the outer diameter of the magnet 34 so that, for example, even when the magnet mounting base 30a is thermally expanded, the magnet 34 is not damaged.

The hall element 36 is assembled to the hall element installation substrate 38 and is disposed in the vicinity of the outer periphery of the magnet 34 in a non-contact manner.
As is well known, the Hall element 36 is for detecting the rotation of the motor shaft 14 by sensing the magnetic flux of the magnet 34 when the magnet 34 rotates using the Hall effect.

  With the above configuration, when the motor shaft 14 is rotated, the magnet 34 is also rotated along with the rotation of the motor shaft 14. At this time, the Hall element 36 detects the N pole and the S pole of the magnet 34. Rotation is detected.

A magnetic shield plate 42 made of a magnetic material such as an iron plate that attracts magnetism is installed between the Hall element mounting base 30b and the rear surface of the brake yoke 20a. There is a gap 44 between them.
The air gap 44 contributes to prevention and reduction of the magnetic influence on the rotation sensor 40 and the magnet 34. That is, by providing the gap 44, the magnetic shield plate 42 is in a non-contact state with other magnetized components, so that the residual magnetism of the magnetic shield plate 42 is likely to decrease. It is possible to prevent or reduce the magnetic effect of the.
The magnetic shield plate 42, as shown in FIG. 2, when viewed in the radial direction, the magnet 34 is installed in a range that covers the Hall element 36 and the Hall element set置基plate 38, (in FIG. 2, b> a).

Due to the two-layer structure of the magnetic shield plate 42 and the gap 44, as shown in FIG. 3, the magnetic effect on the rotation sensor 40 due to the leakage magnetic flux from the brake shaft 20a and the motor shaft 14 magnetized by the brake yoke 20a is exerted. Prevented / reduced.
As shown in FIG. 3, the magnetic shield plate 42 prevents or reduces the magnetic influence on the rotation sensor 40. As a result, the distance between the electromagnetic brake 20 and the rotation sensor 40 can be reduced (in FIG. 3, c > D)) The overall structure of the motor can be made compact.

  Next, the sealing structure of the motor case 12 according to the first embodiment of the present invention will be described. Here, “sealing” means that a bond, a seal member, or the like is interposed at a place where other parts such as a bracket are fitted to the motor case 12 to prevent moisture or foreign matter from entering from outside air. As a result, it means that components such as the rotation sensor 40 are protected from the outside.

Naturally, the motor case 12 that houses a motor for generating power naturally has a strong structure capable of withstanding the power and vibration. The motor case 12 and the anti-load side bracket 18 are sealed by a sealing process, and a magnetic shield plate 42 made of a magnetic material and a magnet made of a non-magnetic material are mounted in the motor case 12 having the sealed structure. The base 30a and the hall element mounting base 30b are accommodated.
Thereby, all the components of the magnetic shield plate 42 and the rotation sensor 40 are protected from rainwater, dust, and the like, and the impact resistance is also improved.

The sealing structure includes a sealing process by bonding of the mating surfaces of the motor case 12 having a sealing structure and the anti-load side bracket 18, a sealing process by a seal washer of the through bolt portion 48, and the motor shaft 14. This is realized by a sealing process using a V-ring, an O-ring, an oil seal or the like at the insertion portion with the non-load side bracket 18.
Of course, sealing materials such as V-rings, O-rings, and oil seals are properly used depending on whether the sealing structure has a dust-proof function or whether a waterproof function is required.

  As a result of the fact that all of the components of the magnetic shield plate 42 and the rotation sensor 40 are housed in the motor case 12 as described above, the motor 10 with a built-in brake rotation sensor according to the present invention can be moved from the motor rotor 52 toward the fan 50. The motor rotor 52, the magnet mounting base 30a, the magnet 34, the Hall element 36, the Hall element installation substrate 38, the Hall element mounting base 30b, the magnetic shield plate 42, the gap 44, the electromagnetic brake 20, and the fan 50 are arranged in this order.

  Further, in the motor 10 of the present invention, unlike the invention of Patent Document 2 in which a rotation sensor is installed at the motor shaft end portion, the rotation sensor 40 is built in the motor case 12, so a manual shaft is attached to the motor shaft end portion. It becomes possible to make it a specification.

FIG. 4 is a partial cross-sectional view of a motor with a built-in electromagnetic brake rotation sensor according to the present invention, which has a manual shaft specification.
The “manual shaft” refers to a shaft that has been processed into a polygonal shape so that the motor shaft can be rotated by a human hand, and a bolt head is welded to the motor shaft end or rotated with a spanner. The manual shaft is often used for positioning at the time of installation. Usually, after the electromagnetic brake is released, the motor shaft is rotated for positioning.
This facilitates the installation and maintenance of the motor.

Next, FIG. 5 is an enlarged cross-sectional view of the vicinity of the rotation sensor when the L-shaped magnetic shield plate 42 ′ of the second embodiment of the present invention is used.
In this embodiment, the outer end of the magnetic shield plate on the motor shaft side is bent in an L shape, and the tip is directed in the direction of the rotation sensor 40 in the axial direction to form an L-shaped magnetic shield plate 42 ′. This L-shaped magnetic shield plate 42 ′ is preferable because it can absorb even a portion of the magnetism closer to the rotation sensor 40 as compared with the first embodiment.

FIG. 1 is a longitudinal sectional view of a rotation sensor built-in motor with an electromagnetic brake according to a first embodiment of the present invention, and is a view of an internal structure viewed from the side. FIG. 2 is an enlarged cross-sectional view of the vicinity of the rotation sensor according to the first embodiment of the present invention. FIG. 3 shows the state of magnetic flux leakage from the brake yoke and the motor shaft of the rotation sensor built-in motor with electromagnetic brake according to the first embodiment of the present invention, and FIG. 3 (a) shows the magnetic shield of the present invention. The figure when a board is not installed, FIG.3 (b) is a figure when the magnetic shield board of 1st Embodiment of this invention is installed. FIG. 4 is a partial cross-sectional view of a rotation sensor built-in motor with electromagnetic brake according to the present invention, which has a manual shaft specification. FIG. 5 is an enlarged cross-sectional view of the vicinity of the rotation sensor when the L-shaped magnetic shield plate of the second embodiment of the present invention is used. FIG. 6 is a cross-sectional view of a main part of a motor disclosed in Japanese Patent Laid-Open No. 2001-238426. FIG. 7A is a partial longitudinal sectional view showing the structure of the entire motor disclosed in Japanese Patent Laid-Open No. 2005-124259, and FIG.

Explanation of symbols

10: Motor with built-in rotation sensor with electromagnetic brake 12: Motor case 14: Motor shaft 20: Electromagnetic brake 30a: Magnet mounting base (rotation sensor mounting base)
30b: Hall element mounting base (rotation sensor mounting base)
40: Rotation sensor 42: Magnetic shield plate 42 ': L-shaped magnetic shield plate 44: Air gap 50: Fan 52: Motor rotor

Claims (3)

In a rotation sensor built-in motor with a magnetic shaft and electromagnetic brake,
The rotation sensor is composed of a magnet, a Hall element, and a Hall element installation substrate, and the mounting base of the rotation sensor is composed of a nonmagnetic material,
The motor includes a motor rotor and a fan, and a magnetic shield plate made of a magnetic material through a gap between a back surface of a brake yoke of the electromagnetic brake and a rotation sensor includes the magnet, the hall element, and the hall element installation substrate. It is provided in a range that covers in the radial direction ,
The motor rotor, the rotation sensor, the magnetic shield plate, the air gap, the electromagnetic brake, and the fan are arranged in this order from the motor rotor to the fan.
Motor with built-in rotation sensor with electromagnetic brake.   The rotation sensor built-in motor with an electromagnetic brake according to claim 1, wherein the magnetic shield plate is L-shaped and a tip is bent in an axial direction toward the rotation sensor.   The motor with a built-in rotation sensor with an electromagnetic brake according to claim 1 or 2, wherein the rotation sensor and the magnetic shield plate are built in a motor case having a sealed structure.

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