JPH11289729A - Rotor for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor for motor, the magnetic poles of which is capable of being positioned precisely relative to the rotating direction detecting the origin of a rotational position detector. SOLUTION: A rotor 1 is constituted by laminating discoid magnetic steel sheets having key projecting sections 21 on their inner peripheries upon another in the direction of the rotating shaft 9 of the rotor 1, while the magnetic steel sheets 12 are rotated from each other by very small amounts in the rotating direction. On the outer peripheral side surface of the rotating shaft 9 on the other side, a skew key groove 22 having a width corresponding to the key projecting sections 21 of the magnetic steel sheets 12 is formed at the same lead angle as that of the laminated rotor 1. In the rotational position detector attaching section of the shaft 9 provided at the rear end of the shaft 9, a key groove 17 is formed for positioning a rotational position detector in the direction of rotation at an angle fixed relative to the skew key groove 22 formed on the shaft 9. Consequently, by having the magnetic poles of the rotor 1 positioned accurately relative to the rotating direction detecting origin of the rotational position detector, the key projecting sections 21 of the core 15 are put in and moved along the skew key groove 22 of the rotating shaft 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rotor for an electric motor,
More particularly, the present invention relates to a configuration of rotors of electric motors stacked and arranged with a skew angle.

[0002]

2. Description of the Related Art As one type of synchronous motor, a reluctance motor is well known. In a normal case, windings to which an alternating current is supplied at predetermined time phases are wound around a plurality of slots of a stator, respectively. , The stator forms a rotating magnetic field. A rotor is rotatably supported inside the stator. The rotor has a rotor core in which a plurality of magnetic steel sheets are stacked, and a plurality of magnetic poles having different magnetic resistances are provided on the surface of the magnetic steel sheet. The synchronous rotation which can perform desired position control and speed control can be performed by forming. FIG. 4 is a longitudinal sectional view of a stator 2 and a rotor 1 of a conventional reluctance motor, and FIG. 5 is a transverse sectional view of the reluctance motor. In the reluctance motor as shown in FIGS. 4 and 5, the rotational position detector 8 accurately detects the rotational position of the rotor magnetic pole 3 with respect to the stator 2, and is optimal for the winding 5 wound around the slot 4. The motor is driven while performing position control and speed control by passing current. FIG.
In the conventional device, the stator 2 includes 24 slots 4, and alternating currents having a phase difference of 120 degrees are sequentially supplied to the windings 5 wound around the respective slots 4 to obtain a desired alternating magnetic field. On the other hand, the rotor 1 has an iron core structure in which a plurality of electromagnetic steel plates 12 are stacked in the axial direction, and a plurality of slits indicated by reference numeral 6 are provided on the surface of each electromagnetic steel plate 12, and the slit 6 has a magnetic resistance. Due to the large size, the rotor 1 forms rotor magnetic poles 3 having different magnetic resistances in the direction of rotation, and the conventional apparatus shown in FIG. 4 has four magnetic poles. Therefore, in order to correctly detect the position of the rotor magnetic pole 3 from the outside, the above-described rotation position detector 8 is fixed to one end 9a of the rotation shaft 9. For this reason, with respect to the rotor, the rotation position detector 8 and the rotation shaft 9 are positioned such that the rotation direction detection origin of the rotation position detector 8 and the rotation position of the rotor magnetic pole 3 are relatively constant. It is necessary to fix the rotor 1 so as to accurately position it.

A conventional technique for positioning the origin of rotation direction detection of the rotational position detector 8 and the rotor magnetic pole 3 so as to be relatively constant will be described with reference to FIGS. Generally, in order to correctly position the rotor core composed of the laminated electromagnetic steel sheets 12 and the rotating shaft 9, a key connection between them is sufficient. However, in the illustrated conventional reluctance type electric motor, the rotating ripple and the like are required. In order to reduce, the laminated electromagnetic steel sheets 12 are attached to the rotating shaft 9 with a slight skew in the axial direction of the rotating shaft 9, respectively.
For this reason, there is a problem that the positioning accuracy between the rotor core and the rotating shaft 9 is significantly reduced as described later. In FIGS. 4 and 5, a key 1 in which a rotor 1 laminated in the rotation axis direction while rotating the electromagnetic steel sheet 12 by a small amount in the rotation direction is skewed to the rotation axis 9 and mounted.
Attached to the shaft along 6. Further, a key groove 17 is formed in the rotation position detector mounting portion of the shaft rear end 9a so as to have a fixed angle relative to the key 16, and a positioning pin (not shown) of the rotation position detector 8 is provided. Keyway 17
And the rotor magnetic pole 3 can be positioned at a relatively constant value by fixing the rotation direction detection origin of the rotation position detector. As shown in FIG. 5, the stator 2 is fixed to a frame 11, and a rotating shaft 9 is supported by a bearing 10 provided on the frame 11.

[0004]

However, the above-mentioned prior art has the following problems.

In the prior art, when the rotor core 15 is mass-produced, electromagnetic steel sheets of the same shape, which are usually processed by press working using a progressive die, are automatically laminated in the die by using caulking. In general, a method of manufacturing the device at a low cost is used. When such a rotor core 15 is fitted along the key 16 attached to the rotating shaft 9, the groove 7 formed on the inner peripheral portion of the electromagnetic steel plate 12 is twisted and laminated with a skew angle. Similarly, it is necessary to use a twisted key having a lead for the key attached to the rotating shaft 9. However, processing such a twisted key requires a high processing technique and is a very expensive part. Therefore, it is general to substitute a straight and elongated prismatic key 16 which is usually manufactured separately. It is. When such an elongated prismatic key 16 is fixed to the outer periphery of the rotating shaft 9 with a skew angle, the two cannot come into close contact with each other, but they can be integrally fixed by brazing or bonding. . However, in order to fit the groove 7 of the rotor core 15 laminated with a lead into such a linear key 16, the width of the groove 7 must be processed to be wider than the width of the key 16. . That is, the key 16
Is fixed to the surface while floating from the rotating shaft 9, the key 16 is substantially larger than the groove 7, and the groove 7 of the electromagnetic steel plate 12 is always fitted with the largest key cross section. A punching process must be performed. For this reason, a gap is generated between some of the magnetic steel sheets 12 in a state where the magnetic steel sheets 12 are fitted to the keys 16, and the positioning accuracy is remarkably deteriorated. Therefore, the rotor magnetic pole 3 with respect to the stator 2
Cannot be accurately detected by the rotational position detector 8 and the current cannot flow to the optimal slot position according to the position of the rotor magnetic pole 3, so that the output of the motor decreases. There was a problem. There is also a method of managing the rotation direction detection origin correction data of the rotation position detector 8 for each electric motor in order to avoid the output reduction. However, when the rotation position detector 8 is replaced, the correction is performed again. Since the value of the data must be changed, and this correction data cannot be measured in many cases in a state of being mounted on the machine, it is common practice to avoid a method of managing the correction data for each electric motor. For this reason, it has been important to develop a technique for positioning the rotation direction detection origin of the rotation position detector 8 and the rotor magnetic pole 3 so as to be relatively constant. Further, according to the above prior art, the rotor core 1
After laminating No. 5, it is necessary to inspect in a separate process whether or not the lamination is performed at an accurate skew angle, which causes an increase in manufacturing cost.

The present invention solves the above problems,
An object of the present invention is to provide a rotor of an electric motor capable of precisely positioning a rotation direction detection origin of a rotation position detector and a rotor magnetic pole position to be relatively constant.

[0007]

In order to achieve the above object, a rotor of a motor according to the present invention has a fixed slot having a plurality of slots each wound with a winding to which an alternating current is supplied at a predetermined time phase. A rotor, a rotating shaft rotatably supported inside the stator, and a rotor core in which a plurality of electromagnetic steel sheets fixed to the rotating shaft and forming a plurality of magnetic poles having different magnetic resistances on the surface are stacked and arranged. And a rotor having: a key projection protruding inwardly provided in an inner peripheral hole of the electromagnetic steel plate, the inner peripheral hole engaging with the rotating shaft, and the rotating shaft being provided on an outer periphery thereof. A key groove to be fitted with a key protrusion of the magnetic steel sheet is carved with a predetermined skew angle, and the magnetic steel sheets are stacked with a predetermined skew angle in a state where the magnetic steel sheets are mounted on a rotating shaft.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of a rotor of a motor showing an embodiment of the present invention. FIG. 2 is a sectional view and a side view of a rotor core constituting the rotor of the electric motor shown in FIG.
FIG. 2 is an explanatory diagram of a rotating shaft that forms a rotor of the electric motor shown in FIG. 1. 1, 2 and 3, 1 is a rotor, 9 is a rotating shaft, 12 is an electromagnetic steel plate, 13 is a collar for balancing,
Reference numeral 17 denotes a key groove for positioning the rotational position detector in the rotation direction, reference numeral 21 denotes a key protrusion, and reference numeral 22 denotes a skewed key groove. A characteristic feature of the present invention is that the electromagnetic steel sheet 12 punched and formed in the same shape is provided with a key projection 21 protruding inward in an inner peripheral hole 12a fitted with the rotating shaft 9. . The key projection 21 is formed of the electromagnetic steel sheet 1
2 is formed at the same time as stamping and molding with a mold. When such electromagnetic steel sheets 12 are automatically laminated, as shown in FIG. 2, the key protrusions 21 are automatically caulked with a predetermined skew angle given. . On the other hand, as shown in detail in FIG.
The skew key groove 22 to be fitted with 1 is carved with a predetermined skew angle. Therefore, according to the present invention, the rotor core 15 is temporarily laminated as shown in FIG. 2 and is fitted on the rotating shaft 9, and at this time, the key projection 21 is engraved on the outer periphery of the rotating shaft 9. The skewed groove 22 is in close contact with the skewed groove 22, so that the two can be securely fixed at a correct position.

In the present embodiment, the key projection 21 is provided on the inner diameter.
Are laminated in the direction of the rotation axis while rotating by a minute amount in the direction of rotation to form a rotor core 15. On the other hand, the outer peripheral side surface of the rotating shaft 9 has a width that fits into the key projection 21 having the inner diameter of the electromagnetic steel plate 12 and has the same lead angle as the laminated rotor core 15. The processed skew keyway 22 is processed. The skew key groove 22 is formed by rotating a rotary shaft 9 by a lead angle corresponding to the skew of the rotor core 15 while moving a tool for processing the groove in parallel with the rotary shaft. Further, a key groove 17 for positioning the rotational position detector 8 in the rotational direction at a fixed angle relative to the skew key groove 22 formed on the rotary shaft 9 is provided at the rotational position detector mounting portion at the shaft rear end 9a. It has been processed. Therefore, by fitting the key projection 21 having the inner diameter of the rotor core 15 along the skew key groove 22 of the rotating shaft 9, the rotation direction detecting origin of the rotating position detector 8 and the magnetic pole of the rotor are fitted. Positioning is performed so that the position has a relatively constant value. In order to firmly fix the rotor core 15 to the rotating shaft 9, a method of shrink-fitting, press-fitting, or bonding the rotor core 15 to the rotating shaft 9 is often applied. As shown in FIG. 3, one end of the skewed groove 22 is open to the outside at the end of the rotating shaft 9, and the rotor core 15 or the magnetic steel sheet 12 can be easily removed one by one from this open portion. Can be guided to the skew groove 22. Furthermore, the rotor core 15
Normally, automatic lamination is performed using caulking in a progressive die, but there is a limit to the lamination thickness by the mold, and when manufacturing a motor with a lamination thickness exceeding this limit lamination thickness, as shown in this embodiment Then, a plurality of rotor cores 15 may be inserted in the rotation axis direction. Further, even if the rotor core 15 is not formed, the electromagnetic steel plates 12 forming the rotor core 15 are pressed into pieces one by one and the skew groove 22 of the rotary shaft 9 is formed.
It is also possible to provide a rotor similar to that of the present embodiment by fitting the rotor. However, in this case, the assembly time for inserting the electromagnetic steel sheet 12 into the rotating shaft 9 increases, and it becomes difficult to apply fixing methods such as shrink fitting, press fitting, and bonding. There are many. Further, the present invention is not limited to the invention applicable only to the reluctance type electric motor described in the embodiment, but may also be applied to other electric motors such as an induction motor or a permanent magnet synchronous motor having a configuration in which disk-shaped electromagnetic steel sheets are laminated in the rotation axis direction. It is equally applicable. Incidentally, the disk-shaped electromagnetic steel sheet shown in the present invention does not need to be an exact circular shape, and is formed by processing an electromagnetic steel sheet having a salient pole structure having irregularities on the outer periphery or a punched hole such as a slit as shown in the present embodiment. It also includes a magnetic steel sheet having a predetermined shape.

[0011]

According to the present embodiment, a rotor core is formed by laminating a disk-shaped electromagnetic steel sheet having a key projection on the inner diameter in the direction of the rotation axis while rotating the magnetic steel sheet by a small amount in the rotation direction.
A rotating shaft having a skew key groove formed on an outer peripheral side surface of the rotating shaft so as to have a width to be fitted to a key protrusion of an inner diameter of the electromagnetic steel sheet and to have the same skew angle as the laminated rotor core; , The rotor can be precisely positioned so that the rotational direction detection origin of the rotational position detector and the magnetic pole position of the rotor are relatively constant. This allows an accurate current to flow through each slot of the stator in accordance with the position of the rotor magnetic pole, thereby preventing a decrease in the output of the motor. In addition, since the lead angle of the rotor core and the lead angle of the skewed keyway machined on the outer peripheral side surface of the rotating shaft are manufactured so as to match exactly,
It is not necessary to check whether or not the rotor core is manufactured with an accurate lead angle by using the rotor core alone. If the rotor can be inserted into the rotating shaft, it can be determined that the rotor is good. For this reason, it is possible to omit the inspection process of the rotor core and reduce the manufacturing cost.

The present invention is particularly useful when the rotating shaft and the rotor of the so-called IPM motor in which a permanent magnet is embedded in the reluctance motor or the rotor core shown in the embodiment. The reason is that for a motor such as an induction motor having a structure in which a rotor core itself does not have magnetic poles, it is not necessary to perform accurate positioning when coupling the rotor core and the rotating shaft as shown in the present invention. In addition, in the case of a permanent magnet type synchronous motor, it is easier to handle the magnet if it is magnetized after attaching the permanent magnet to the surface of the rotating shaft. In this case as well, it is necessary to position the rotating direction at the stage of attaching the permanent magnet. There is no. Therefore, in a situation where an induction motor or a permanent magnet type synchronous motor is mainly used as in the past, a technique for accurately positioning and coupling the rotor core and the rotating shaft as in the present invention is usually not important. Was. However, like the reluctance type motor and the IPM motor described in the present embodiment,
As motors in which the magnetic poles are formed in advance on the rotor core have become widespread, accurate positioning and coupling technology between the rotor core and the rotating shaft is required as shown in the present invention, and this has become an important technology. is there.

[Brief description of the drawings]

FIG. 1 is a side view of a rotor of an electric motor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view and a side view of a rotor core constituting the rotor of the electric motor shown in FIG.

FIG. 3 is an explanatory view of a rotating shaft constituting a rotor of the electric motor shown in FIG. 1;

FIG. 4 is a sectional view of a stator and a rotor of a conventional reluctance motor.

FIG. 5 is a sectional view of a conventional reluctance motor.

[Explanation of symbols]

1 rotor, 2 stator, 3 rotor magnetic poles, 4 slots, 5 windings, 6 slits, 8 rotation position detector, 9
Rotating shaft, 12 electromagnetic steel sheet, 15 rotor core, 21
Key projection, 22 skew keyway.

Claims (2)

[Claims] 1. A stator having a plurality of slots each wound with a winding to which an alternating current is supplied at a predetermined time phase, a rotating shaft rotatably supported inside the stator, and the rotating shaft. And a rotor having a plurality of electromagnetic steel sheets, the surfaces of which form a plurality of magnetic poles having different magnetic reluctances, stacked on each other, and a rotor having: A key projection protruding toward the inside is provided in the inner peripheral hole to be engaged, and a key groove to be fitted with the key projection of the electromagnetic steel plate is engraved on the outer periphery of the rotating shaft with a predetermined skew angle. A rotor for an electric motor, wherein electromagnetic steel sheets are stacked with a predetermined skew angle in a state where they are attached to a rotating shaft. 2. The rotor for an electric motor according to claim 1, wherein one end of the keyway engraved on the rotary shaft is open at an end of the rotary shaft.