JPH0619287Y2 - Motor with built-in detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an induction motor, and more particularly to an electric motor having a built-in detector for detecting the rotational state of a rotor.

(Prior Art) As is well known, an induction motor is a device that rotates a rotor with respect to a stator by an electromagnetic force that acts between a coil-wound stator and the rotor. Some have a built-in detector for detecting the rotational state of the rotor. The detector includes a detector stator that is integrated with the stator and a detector rotor that is integrated with the rotor and is located adjacent to the detector stator. There is a tricky problem with the placement of the detector here.

(Problems to be solved by the present invention) That is, if the stator and the detector are too close to each other,
Leakage magnetic flux leaking from the coil of the stator affects the detector and deteriorates the detection sensitivity. In particular, when the arm is attached to the output shaft of this electric motor and it is used for a direct drive of a robot, the above-mentioned decrease in detection sensitivity becomes remarkable. According to an experiment conducted by the inventor by attaching an arm (about 800 mm) to the output shaft of the electric motor, the output of the detector, which should be a sinusoidal curve, is disturbed by the electromagnetic effect of the magnetic flux leaking and the robot is operating. The arm may vibrate and generate noise. This tendency is less of an issue when the arm operates at high speeds, but an important issue when operating at low speeds. Also, when a closed-loop servo is used to control the electric motor, if the electric motor is stopped with the coil being excited, the arm will vibrate without stopping at a predetermined position due to noise, and if a load is applied to this arm, The vibration of the arm becomes large and becomes a problem.

If the detector is moved further away from the influence of the leakage magnetic flux, the size of the electric motor will increase, the electric motor will become heavier, the inertia resistance will increase, and the manufacturing cost will increase, which is not desirable. Of.

In view of the above circumstances, the present invention solves the above-mentioned drawbacks in the prior art, that is, prevents the induction noise of the stator coil from adversely affecting the detector without increasing the electric motor as compared with the conventional one. Therefore, the object of the present invention is to provide an improved electric motor that operates smoothly and does not generate vibrations in the arm and the like when stopped.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a dead space between the stator and the detector is used, and the leakage magnetic flux reaches the detector in this space. That is, a magnetic blocking member for blocking the magnetic field is arranged. Specifically, a plurality of pole pieces 3 fixed to the housing 10 and wound with a coil 38
An annular inner stator 28 having 6 on its outer surface, an outer stator 26 fixed to the housing and having on its inner surface a plurality of pole pieces 34 wound with coils 32 facing each pole piece of the inner stator, An annular rotor 44 concentrically and rotatably arranged between the inner stator pole piece and the outer stator pole piece, and integrated with the rotor at a position axially separated from the rotor. Detection consisting of a fixedly mounted detector rotor 92 and a detector stator 86 having poles around which a coil 88 is wound and arranged laterally of the outer stator and radially opposite the detector rotor 92. A motor with a built-in detector that drives the rotor by a magnetic circuit that forms a magnetic flux penetrating in a radial direction between the facing inner and outer pole pieces and that detects the rotational state of the rotor by the detector. Is the premise.

In such an electric motor, an annular magnetic shield member 77 made of a magnetic material is fixedly arranged in the housing between the outer stator and the detector stator, and is disposed between the rotor and the inner stator and the detector rotor. Further, a magnetic shield member 79 made of a magnetic material is arranged so as to face the magnetic shield member, and a spacer 56 made of a non-magnetic material is arranged between the magnetic shield member and the rotor.

Since the leakage magnetic flux is prevented from reaching the detector by the blocking members 77 and 79, the detection sensitivity of the detector can be increased without moving the detector away from the stator. Moreover, since the space in which the blocking member is arranged is originally a dead space, the size of the electric motor will not increase due to the placement of this blocking member.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the housing 10 has a flange portion 12 extending in the radial direction, and a conical portion 14 having a diameter gradually decreasing in succession thereto. The outer stator 2 is attached to the housing 10 by bolts 16 and a stator pressing ring 22.
6 is attached, and the inner stator 28 is attached by the bolt 18 and the stator pressing ring 24. Each of the stator pressing rings 22 and 24 has an arcuate inner surface, and has an overhanging portion 23 or 25 that projects outward from the mounting surface side.
Is equipped with.

As shown in FIG. 2, the outer stator 26 and the inner stator 28 both have an annular shape, and the coil 32 is wound around a plurality of pole pieces 30 spaced apart from each other on the inner peripheral surface of the outer stator 26. A plurality of pole piece teeth 34 are formed on the inner peripheral surface. On the other hand, a plurality of pole pieces 36 are similarly spaced on the outer peripheral surface of the inner stator 28, a coil 38 is wound around the pole piece 36, and a plurality of pole piece teeth 42 are formed on the outer peripheral surface thereof. .

An annular rotor 44 is arranged between the two stators 26 and 28, and the pole piece teeth 34 are provided on the outer peripheral portion and the inner peripheral portion thereof, respectively.
A plurality of teeth 46 and 48 facing each other are circumferentially spaced. Spacers 54 and 56 are provided at both ends of the rotor 44.
And the spacer 54, the rotor 44, and the spacer 56 are integrally attached to the end surface of the annular (hollow) output shaft 58 by the bolt 52. On the inner peripheral surface of the output shaft 58, an outer ring retaining ring 64 tightened to the output shaft 58 with a bolt 62.
The pair of outer rings 68 of the cross roller bearing 66
Is attached. The outer ring pressing ring 64 has a surface that faces the stator pressing ring 24 with a slight clearance, and has a surface that is an extension of the arc outer surface of the overhanging portion 25 of the stator pressing ring 24.

The inner ring 72 of the cross roller bearing 66 is fitted to the bearing mounting surface at the tip of the conical portion 14 of the housing,
It is attached to the housing 10 by an inner ring retainer 83 that is tightened by a bolt 81 screwed together. The cross roller bearing 66 includes a large number of cylindrical rollers 74 in which the axes of a pair of outer ring 68 and inner ring 72 are alternately changed in a right angle direction.

A spacer 78 is attached to the stator pressing ring 22 by a bolt 76.
Is attached to the stator holding ring 22 and the spacer 78.
Holds the outer surface of the disk-shaped magnetic shield plate 77. A ring-shaped magnetic shield rotor 79 is provided between the spacer 56 and the output shaft 58 so as to face the shield plate 77. The spacer 78 is attached to the spacer 78 by a bolt 82.
A disk-shaped synchro stator 86 is attached by a stator attachment plate 84 that is tightened to 8. The stator 86 has pole pieces and pole piece teeth similar to those of the outer stator 26, and a synchronizing coil 88 is wound around this pole piece. A synchro rotor 92 is attached to the output shaft 58 so as to face one pole tooth of the synchro stator 86. A cover 96 is attached to the stator mounting plate 84 by a bolt 94 so as to cover the stator 86, the rotor 92, etc., and a seal 98 is interposed between the inner peripheral surface of the cover 96 and the outer peripheral surface of the output shaft 58. There is. Reference numeral 102, which is shown as a half cross section in the lower half of FIG. 1, is a motor connector, and 104 is a synchronizing connector.

Next, the operation and effect of this embodiment will be described. This electric motor has three phases and includes an outer stator 26 and an inner stator 2.
Every 8th coil 32 and 38 is excited. When the coils 32 and 38 are energized, a magnetic flux is generated in the pole pieces 30 and 36, which flux is present on the pole piece 30 with the outer stator 26.
A closed-loop magnetic field between the pole piece 36 of the inner stator 28 facing the pole piece 36, the third pole piece 30 of the outer stator 26 from the pole piece 30 and the pole piece 36 of the inner stator 28 facing the pole piece 36. Make up the circuit. That is, the magnetic flux extends in the circumferential direction between the pole pieces 30 of the outer stator 26 and between the pole pieces 36 of the inner stator 28, and between the pole pieces 30 of the outer stator 26 and the pole pieces 36 of the inner stator 28 the rotor 44. Extending radially across.

Further, the pitch between the pole piece tooth 34 of the pole piece 30 of the outer stator 26 and the outer tooth 46 of the roller 44, and the pitch of the pole piece tooth 42 of the pole piece 36 of the inner stator 28 and the inner tooth 48 of the rotor 44 are different from each other. Therefore, due to the action of the magnetic flux, a force for continuously aligning the pole piece teeth 34, 42 and the teeth 46, 48 is continuously generated, and as a result, the rotor 44 causes the stators 2 and 2 to rotate.
It is rotated with respect to 6, 28. However, since this is known, detailed description will be omitted.

When a rotational force is generated in the rotor 44, the output shaft 58 supported by the cross roller bearing 66 rotates integrally with the rotor 44, so that the rotation can be extracted by connecting the rotated mechanism to the output shaft 58. Cross roller bearing 66
Advantageously, only one can support loads in both thrust and radial directions.

Most of the magnetic flux forms a closed loop between the coil 32 of the outer stator 26 and the coil 38 of the inner stator 28, and a part of the magnetic flux also exists in the axial direction of the stators 26 and 28 (left-right direction in FIG. 1). This leakage flux may be detected by the detector 1 including the stator 86, the coil 88 and the rotor 92.
As described above, when the number reaches 00, the detection sensitivity is impaired. However, according to this embodiment, there is no fear that such a situation will occur. That is, the magnetic shield plate 7
7, stator pressing ring 22, inner and outer stators 28, 26,
Both the rotor 44 and the magnetic shield rotor 79 are made of a magnetic material, and the outer ring pressing ring 64 and the spacer 78 are made of magnetic iron (the magnetic shield plate 77 is made of a silicon steel plate and has a thickness of 3 sheets of 0.5 mm are used), and the spacer 56 and the output shaft 58 are made of a non-magnetic material. Therefore, from the coil 32 of the outer stator 26 to the detector 100.
The magnetic flux that tries to leak in the direction of the direction is absorbed by the magnetic shield plate 77 and the stator pressing ring 22, while the magnetic flux that tries to leak from the coil 38 of the inner stator 28 toward the detector 100 and the spacer 56 and. It is shut off by the output shaft 58. Therefore, there is no concern that the leakage magnetic flux reaches the detector 100. Although it is effective to absorb the leakage flux on the coil 88 side of the detector 100 with the shield plate 77 or the like, by blocking the leakage flux on the rotor 92 side with the spacer 64 or the like, the leakage flux The shielding will be more complete.
In addition, the above is to provide the protrusions 23 and 25 on the stator pressing rings 22 and 24 to reduce the magnetic resistance, and finally to arrange the magnetic shield plate 77 and the magnetic shield rotor 79 in the space which has conventionally been a dead space. This is achieved (in consideration of the materials of the various members), and the size of the electric motor (particularly the axial dimension) does not substantially increase at all.

The above description is merely an embodiment of the present invention.
The present invention should not be construed as limited to this. For example, the magnetic shield member 77, the magnetic blocking rotor 7
The shape, size, etc. of 9 or spacer 56 can be appropriately changed as necessary.

(Effects of the Invention) As described above, according to the present invention, a magnetic shield plate made of a magnetic material is disposed between the outer stator and the detector stator, and is disposed between the rotor and the inner stator detector stator. A magnetic blocking member made of a magnetic material is arranged to face the magnetic shield plate, and a spacer made of a non-magnetic material is arranged between the magnetic blocking member and the rotor. This prevents the leakage flux of the outer stator from adversely affecting the detector, and the rotational state of the rotor can be accurately detected by the detector. here,
Since the space in which the magnetic shield plate and the like are arranged is originally a dead space, there is no fear that the electric motor becomes large due to the arrangement of the magnetic shield plate and the like.

[Brief description of drawings]

FIG. 1 is a front view (upper half sectional view) showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. [Description of symbols of main parts] 10 ... Housing 26, 28 ... Stator 32, 38 ... Coil 44 ... Rotor 58 ... Output shaft 77 ... Magnetic shield plate 79 ... Magnetic shield rotor 86 ... Detector Stator 92 ... Detector Rotor 100 ... Detector

Claims (1)

[Scope of utility model registration request] 1. An annular inner stator fixed to a housing and provided on its outer surface with a plurality of coil-wound pole pieces, and a coil wound so as to face each pole piece of the inner stator fixed to the housing. An outer stator having a plurality of pole pieces on its inner surface, an annular rotor concentrically and rotatably disposed between the pole pieces of the inner stator and the pole pieces of the outer stator, A detection rotor fixed integrally with the rotor at a position axially distant from the rotor and a pole around which a coil is wound are arranged laterally of the outer stator and radially opposite the detector rotor. A detector composed of a fixed detector, and driving the rotor by a magnetic circuit that forms a magnetic flux penetrating in a radial direction between the facing inner and outer pole pieces, and rotating the rotor by the detector. detection In the electric motor with a built-in detector, an annular magnetic shield member made of a magnetic material is fixedly arranged in the housing between the outer stator and the detector stator, and the rotor and the inner stator and the detector are arranged. A magnetic blocking member made of a magnetic material is arranged between the rotor and the rotor so as to face the magnetic shielding member, and a spacer made of a non-magnetic material is arranged between the magnetic blocking member and the rotor. Electric motor with built-in detector.