JP5167855B2 - Fixing method of motor stator - Google Patents

Description

  The present invention relates to a fixing method of an electric motor stator that suppresses deterioration of characteristics of an electromagnetic steel sheet.

  In recent years, there is an urgent need to reduce energy consumption due to global warming and the depletion of fossil fuels. And since most of the electric power is consumed by electric motors, improving the efficiency of various electric motors is becoming increasingly important. Therefore, for the purpose of improving the efficiency of the electric motor, efforts are being made to improve the characteristics of the electromagnetic steel sheet, which is the iron core material of the electric motor, particularly to reduce the iron loss.

  An electric motor generally includes a cylindrical rotor embedded with a magnet and a stator on the outer periphery thereof, and the stator includes a tooth portion and a yoke portion on which windings are applied. The rotor and the stator are made by laminating plates obtained by punching electromagnetic steel sheets into a desired shape and fixing them by caulking or welding. And a stator is fixed to an electric motor case, after giving a coil | winding to the teeth part. There are several methods for fixing the stator to the motor case, but among them, the shrink-fitting method is often used. This method is a method in which an electric motor case having an inner diameter slightly smaller than the outer diameter of the stator is heated to fit the stator, and when cooled to room temperature, the electric motor case contracts and the stator is fixed. However, when this method is used, a large compressive stress is applied to the entire stator. In particular, a large compressive stress is applied along the magnetic path of the stator. When a large compressive stress is applied to the stator, there arises a problem that the efficiency of the motor is remarkably lowered.

  In order to minimize such characteristic deterioration of the electric motor, Patent Document 1 proposes a method for reducing the compressive stress applied to the stator as much as possible.

  Here, it is considered that the main cause of the deterioration of the characteristics of the motor when compressive stress is applied to the stator is the stress dependence of the iron loss characteristics of the electromagnetic steel sheet as the iron core material. For example, as described in Non-Patent Document 1, it is known that when compressive stress is applied to a magnetic steel sheet along the magnetic path direction, the iron loss increases and the magnetic permeability decreases. Therefore, in order to obtain a desired magnetic flux density, the iron loss of the magnetic steel sheet as the iron core material is increased by the compressive stress applied to the stator when the stator is fixed to the motor case, and the magnetic permeability is decreased. It can be interpreted that a large winding current is required, and as a result, the loss of the motor increases and the efficiency decreases.

Conversely, when tensile stress is applied to the electrical steel sheet, as described in Non-Patent Document 1, there is a stress range in which iron loss is reduced and magnetic permeability is increased. Patent Document 2 proposes a shape of the stator and a method for fixing the stator so that tensile stress is applied toward the radially outer side of the stator using this phenomenon.
JP 2005-80451 A JP 2006-223015 JP Yoshihiro Tani, Masahiro Ogane, Hidetsugu Arita, Masatsugu Nakano, Shinichi Yamaguchi, Yukari Tode, Takashi Yoshioka, Chiyo Fujino, "Measurement of Magnetic Properties of Electrical Steel Sheets under Stress," IEEJ Magnetics Study Group Material MAG-03 -191

  However, the method of reducing the compressive stress applied during shrink fitting described in Patent Document 1 cannot be completely removed even if the stress is reduced to the maximum. Because it is a method of fixing the stator to the motor case by applying compressive stress, if this stress is too small, the stator may move while the rotor is rotating, and it operates as a normal motor. It is not possible. As described in Non-Patent Document 1, in an electromagnetic steel sheet, iron loss increases rapidly due to a small compressive stress. Considering this, there is a possibility that the motor characteristics may be deteriorated even with a small amount of compressive stress necessary for fixing the stator.

  Further, as a method for fixing the stator to the motor case, methods other than shrink fitting include press-fitting and bolt tightening. In press-fitting, pressure is applied to the case so that the compressive stress after fixing is basically the same as that by shrink fitting, and compressive stress is applied to the entire stator. On the other hand, although bolting does not apply compressive stress to the entire stator, local distortion occurs at the bolting location. Since the magnetic properties of the steel sheet made of iron core material deteriorate due to local strain, it is presumed that the fixing method of the stator by bolting also impairs the characteristics of the electric motor.

  In patent document 2, it fixes by giving a tensile stress to a stator, and the problem of the characteristic deterioration of the electromagnetic steel plate by a compressive stress is solved. However, there is a concern that while the electric motor is rotating, the temperature rises due to the iron loss or copper loss of the material forming the rotor or stator, and the fixing force of the coupling portion is weakened.

  The present invention has been made in view of the above points, and prevents the deterioration of material characteristics by not applying a compressive stress to the stator core, and the electric motor stator whose fixing force does not change even when the temperature rises. The purpose is to propose a fixing method.

  In the present invention, in order to solve the above problem, first, unlike the conventional method of fixing a stator to a motor case while applying compressive stress, the stator is attached to the motor case while applying tensile stress to the stator. Focused on the fixing method. Then, it has been proposed to connect an electric motor stator (hereinafter abbreviated as a stator) and an electric motor case (hereinafter abbreviated as a case) by fitting the concave and convex portions. Furthermore, when the thermosetting resin adhesive is filled in the joint between the stator and the case, the heat shrinks due to curing, and the tensile stress is applied to the magnetic steel sheet that is the iron core material. It has been found that the fixing effect between the stator and the case does not decrease due to the adhesive effect even when the temperature rises, and has excellent characteristics.

  The present invention has been made based on such findings, and the gist thereof is as follows.

[1] The motor stator has a fan-shaped convex portion on the outer periphery of the yoke portion, the motor case has a fan-shaped concave portion on the inner periphery, and the motor is fixed by fitting the convex portion and the concave portion together. An electric motor stator fixing method, comprising: connecting a child and the electric motor case; and filling a connecting portion between the electric motor stator and the electric motor case with a thermosetting resin adhesive.
[2] The motor stator has a fan-shaped concave portion on the outer periphery of the yoke portion, the motor case has a fan-shaped convex portion on the inner periphery, and the motor is fixed by fitting the concave portion and the convex portion. An electric motor stator fixing method, comprising: connecting a child and the electric motor case; and filling a connecting portion between the electric motor stator and the electric motor case with a thermosetting resin adhesive.
[3] The fan-shaped convex portion described in [1] is formed such that the fan-shaped convex portion center line is located on an extension line connecting the center of the motor stator and the teeth. An electric motor stator fixing method.
In addition, the said fan-shaped convex part center line is a line which connects the position of 1/2 of the circumferential direction width | variety of a convex part, and the center of the fan-shaped which forms the said convex part.
[4] The fan-shaped recess according to [2] is characterized in that the fan-shaped recess center line is formed on an extension line connecting the center of the motor stator and the teeth. To fix the motor stator.
The fan-shaped recess center line is a line that connects a position that is half the circumferential width of the recess and the center of the sector that forms the recess.
[5] In any one of the above [1] to [4], the bonding portion filled with the thermosetting resin adhesive is heated to cure and heat shrink the thermosetting resin adhesive. A method for fixing an electric motor stator, wherein tensile stress is applied to the electric motor stator.

According to the present invention, there is provided a method of fixing an electric motor stator in which no compressive stress is applied to the iron core of the stator so that the material characteristics do not deteriorate and the fixing force does not change even when the temperature rises.
Furthermore, the magnetic characteristics of the electrical steel sheet constituting the stator can be improved by the tensile stress acting on the stator. As a result, the loss of the electric motor is reduced, and an electric motor with high efficiency can be provided.
From the above, as compared with the conventional electric motor, the winding current is reduced due to the increase in the magnetic permeability of the electromagnetic steel plate of the stator, the copper loss is reduced, and the miniaturization of the stator is achieved by the reduction of the number of windings.

In the present invention, when a stator constituting a part of an electric motor is fixed to a case, the stator has a fan-shaped convex portion (or a concave portion) on the outer periphery of the yoke portion, and the case has a fan-shaped concave portion (or a concave portion on the inner periphery). Or a convex portion). And the said stator and the said case couple | bond together by fitting the said convex part and the said recessed part. Thereby, the compressive stress added to a stator can be avoided and the characteristic deterioration of the electromagnetic steel plate which is an iron core material can be suppressed.
Further, the stator and the case are filled with a thermosetting resin adhesive, the joint is heated, the thermosetting resin adhesive is cured, and the stator is thermally contracted. Tensile stress is applied to. And the magnetic characteristic of the electrical steel sheet which comprises a stator can be improved with the tensile stress which acts on a stator.
Thereby, the iron loss of the electromagnetic steel sheet which is a stator core material is reduced, the magnetic permeability is increased, and as a result, the efficiency of the electric motor can be improved.

An example of the best mode for carrying out the present invention is shown below.
First, FIG. 1 shows a schematic diagram of a method for fixing a stator by conventional shrink fitting. 1, the case ring 2 having an inner diameter slightly smaller than the outer diameter of the stator 1 is heated to a constant temperature, and the stator 1 is placed inside the case ring 2 that has become larger due to thermal expansion. Next, the case ring 2 contracts as the temperature of the case ring 2 decreases, and as a result, the stator 1 is fixed.
In addition, in the method by press fitting, a load is applied without heating the case ring 2 and the stator 1 is fitted into the case ring 2.
In either case of the shrink fit method or the press fit method, a compression stress is applied to the stator after fixing.
On the other hand, an embodiment of a method for fixing an electric motor stator according to the present invention is shown in FIGS. The present invention is a method for avoiding compressive stress and applying tensile stress to the stator. As shown in FIGS. 2 and 3, the stator 1 has a fan-shaped convex portion 4 on the outer periphery of the yoke portion 3. The case 5 has a fan-shaped recess 6 on the inner periphery. Then, the stator 1 is heated and then inserted into the case 5, or after the case 5 is cooled, the stator 1 is inserted or press-fitted, and the convex portion 4 and the concave portion 6 are fitted together, as shown in FIG. 4. Thus, the stator 1 and the case 5 are coupled. The stator 1 is fixed to the case 5 when the temperature reaches room temperature.

  Further, in the present invention, in addition to the above, a thermosetting resin-based adhesive 7 is filled in the joint portion of the stator 1 and the case 5. The joining portion filled with the thermosetting resin adhesive 7 is heated, the thermosetting resin adhesive 7 is cured and thermally contracted, and the stator 1 starts from the stator protrusion 4. A tensile stress is further applied to the outside in the radial direction.

  2 and 3, an example in which the fan-shaped convex portion is formed on the stator 1 side and the concave portion is formed on the case 5 side is opposite. On the contrary, the concave portion is on the stator 1 side and the convex portion is on the case. The object can be achieved even if it is formed on the 5 side. Depending on the width of the yoke, the width of the teeth, the expected magnetic flux density distribution, and the like, a preferable convex portion or combination of concave portions can be selected as appropriate.

Examples of the thermosetting resin adhesive include epoxy resin, phenol resin, and melanin resin adhesives. These are applied to the inner surface of the case in advance, or the stator is inserted into the case and then filled into the joint gap. As the stator, magnetic steel plates are laminated and fixed, and an adhesive is often used for fixing between the plates. It is more preferable that the adhesive used at this time oozes out of the stator during lamination and fills the gaps in the coupling portion. It is also possible to increase the fixing force by mixing a filler together with an adhesive in the joint gap.
Then, after inserting the stator into the case, the bonded portion is heated to the thermosetting temperature, the thermosetting resin adhesive is cured and thermally contracted, and a tensile stress is applied to the stator, thereby finally The stator and case are fixed.

  The fan-shaped convex portion 4 shown in FIG. 2 is formed so that the fan-shaped convex portion center line is located on an extension line connecting the center of the stator and the teeth 8 as shown in FIG. This is preferable because tensile stress is also applied in the radial direction (magnetic path direction) of the teeth. The fan-shaped convex center line is a line connecting the position of half the circumferential width and the sector-shaped center formed by the convex portion, as shown in FIG.

FIG. 5 is an enlarged view of the fan-shaped convex portion 4 of the stator, and FIG. 6 is an enlarged view of the fan-shaped concave portion 6 of the case. According to FIG. 5 and FIG. 6, it is preferable that the fan-shaped opening angle of the stator convex portion is slightly smaller than the fan-shaped opening angle of the concave portion provided in the inner periphery of the motor case. When the electric motor continues to rotate and the temperature rises, the filled resin expands thermally. However, by providing a difference in the opening angle of the fan-shaped base part, the stator will be pulled further due to the expansion of the resin present in this part, and the fixing force will not decrease even if the temperature rises become.
When the motor stator has a fan-shaped recess on the outer periphery of the yoke and the motor case has a fan-shaped protrusion on the inner periphery, the fan-shaped opening angle of the motor stator recess is It is preferable to make it slightly larger than the fan-shaped opening angle of the convex portion provided on the periphery. In this case as well, the fan-shaped concave portion of the stator is formed so that the fan-shaped concave portion center line is located on an extension line connecting the center of the stator and the tooth 8. This is preferable because tensile stress is also applied in the radial direction (magnetic path direction). The fan-shaped recess center line is a line connecting the position of half the circumferential width of the recess and the center of the sector formed by the recess.
As described above, the present invention not only prevents the deterioration of the iron core magnetic characteristics due to the method of fixing the stator to the case, but also actively improves the iron core magnetic characteristics from the viewpoint of the motor structure. It is. Furthermore, the present invention addresses this problem of deterioration of iron core magnetic properties (iron loss) that occurs when the case and the stator are fixed using strong stress acting on the outer periphery of the motor core, such as shrink fitting and press fitting. The main purpose is not only to prevent such deterioration, but also to provide a method for improving the magnetic properties of the iron core from those expected from the material. From such a point, the present invention is optimal for an inner rotor type motor having a large adverse effect of the compressive force applied to the yoke portion because the yoke portion has a long circumference.

An electric motor having the same shape and structure as FIG. 7 was produced as follows. The electric motor was an 8-pole 12-slot concentrated winding brushless DC motor (surface magnet type, inner rotor type). Stator 1 is a JIS50A400 grade 0.5 mm thick non-oriented electrical steel sheet that is press-punched into the shape shown in Fig. 2 and laminated to 195 sheets. After fixing, cover the teeth 8 with a bobbin, and then wind the coil. did. The overall thickness is 100 mm. The outer diameter (excluding protrusions) of the stator is 180 mm, the inner diameter is 80 mm, the yoke width is 8 mm, and the teeth width is 10 mm. Further, as shown in FIG. 2, twelve convex portions 4 on the sector shape are formed on the outer periphery of the yoke portion 3 so that the center line thereof is located on an extension line connecting the center of the stator and the teeth. As shown in FIG. 4, the outer periphery of the fan-shaped convex portion 4 is along a concentric circle of the yoke portion 3, the radial width is 7 mm, the opening angle is 110 °, and the circumferential width is 12 mm.
On the other hand, the case 5 was manufactured from an aluminum alloy. A fan-shaped recess 6 is formed on the inner periphery of the case 5, and a one-component epoxy resin adhesive is applied in advance to the inside of the recess 6 of the case 5 so that the fan-shaped recess and the protrusion are aligned. And the stator 1 were inserted into the case 5 and heated at 150 ° C. for 15 minutes to be cured and bonded. As shown in FIG. 5, the case 5 has an inner diameter of 181 mm and a wall thickness of 15 mm, has a fan-shaped recess 6, the sector-shaped radial width is 9 mm, the opening angle is 120 °, and the circumferential opening width. Is 12.5 mm.
The electric motor obtained as described above is referred to as electric motor A.

  For comparison, as shown in FIG. 1, the same number of magnetic steel sheets punched into a shape having no fan-shaped projections are stacked, and the case is heated to 200 ° C. Was made.

With respect to the two types of electric motors A and B obtained as described above, the motor efficiency was measured under the conditions of a motor rotational speed of 2500 rpm and a torque of 10 Nm. The motor efficiency was evaluated by the ratio between the output and the input power obtained from the torque and the rotational speed (output / input × 100 [%]).
As a result, the efficiency of electric motor A was 93%, while that of B was 89%. It can be seen that the motor example of the present invention has a higher motor efficiency than the comparative example. And it has confirmed that the electric motor of the outstanding characteristic was obtained.

An electric motor having the shape and structure shown in FIG. 10 was produced as follows.
The motor was an 8-pole 12-slot concentrated winding brushless DC motor (surface magnet type, inner rotor type).
Stator 1 is composed of 97 JIS50A400 grade non-oriented electrical steel sheets of 0.5 mm thickness, stamped into the shape shown in Fig. 8 and laminated, and then the teeth 8 are covered with a bobbin, and then wound. did. The overall thickness is 50 mm. The outer diameter of the stator is 190mm, the inner diameter is 80mm, the yoke width is 13mm, and the teeth width is 10mm. Four fan-shaped recesses 9 were formed on the outer peripheral side of the yoke so that the center line thereof coincided with the center line of the teeth 8. The inner periphery of the fan-shaped concave portion is along the concentric circle of the yoke, the radial width is 7 mm, the opening angle 4c is 110 °, and the circumferential width is 12 mm.
The case 5 has an inner diameter of 180.6 mm (excluding protrusions), a thickness of 12 mm, has a fan-shaped convex portion, the fan-shaped radial width is 9 mm, the opening angle is 120 °, and the circumferential opening width is 5 b. Is 12.5 mm.
After cooling the case 5 made of an aluminum alloy to −20 ° C., the stator 1 having a one-component epoxy resin adhesive previously applied to the inside of the recess is fitted with the fan-shaped uneven portion as shown in FIG. Were inserted into the case 5 and heated at 145 ° C. for 20 minutes to be cured and bonded. This is referred to as an electric motor C.

  The motor efficiency of the electric motor C was measured at a motor rotation speed of 2500 rpm and a torque of 6 Nm. The efficiency was 92%, and it was found that high motor efficiency was obtained.

The effect of the present invention is useful not only in a permanent magnet synchronous motor (brushless DC motor) but also in an electric motor made of a magnetic steel sheet, for example, an induction motor or a switched reluctance motor.

It is a figure which shows the time of the stator insertion state by the conventional shrink-fitting fixing method. It is a figure which shows the shape of one electromagnetic steel plate which forms the stator of this invention. It is sectional drawing of the case which inserts the stator of this invention. It is a fan-shaped convex part enlarged view of the stator of this invention. It is a fan-shaped convex part enlarged view of the stator of this invention. It is a fan-shaped recessed part enlarged view of the case of this invention. It is a schematic diagram when the stator of the present invention is fitted into a case. It is a figure which shows the shape of one electromagnetic steel plate which forms the stator of this invention. It is sectional drawing of the case which inserts the stator of this invention. It is a schematic diagram when the stator of the present invention is fitted into a case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stator 2 Case ring 3 Yoke part 4 Fan-shaped convex part 5 Case 6 Fan-shaped recessed part 7 Thermosetting resin adhesive 8 Teeth 9 Fan-shaped recessed part (stator)

Claims (4)

The motor stator has a fan-shaped convex portion on the outer periphery of the yoke portion, the motor case has a fan-shaped concave portion on the inner periphery, and the motor stator and the The motor case is coupled, and further, the coupling portion between the motor stator and the motor case is filled with a thermosetting resin adhesive, and then the coupling portion filled with the thermosetting resin adhesive is disposed. A method for fixing an electric motor stator, comprising: heating and curing the thermosetting resin-based adhesive and causing heat shrinkage to apply tensile stress to the electric motor stator. The motor stator has a fan-shaped recess on the outer periphery of the yoke portion, the motor case has a fan-shaped protrusion on the inner periphery, and the motor stator and the The motor case is coupled, and further, the coupling portion between the motor stator and the motor case is filled with a thermosetting resin adhesive, and then the coupling portion filled with the thermosetting resin adhesive is disposed. A method for fixing an electric motor stator, comprising: heating and curing the thermosetting resin-based adhesive and causing heat shrinkage to apply tensile stress to the electric motor stator. The fan-shaped convex part according to claim 1, wherein the fan-shaped convex part center line is formed so as to be positioned on an extension line connecting the center of the electric motor stator and the teeth. Item 2. A method for fixing an electric motor stator according to Item 1.
In addition, the said fan-shaped convex part center line is a line which connects the position of 1/2 of the circumferential direction width | variety of a convex part, and the center of the fan-shaped which forms the said convex part. 3. The fan-shaped recess according to claim 2, wherein the fan-shaped recess center line is formed on an extension line connecting the center of the motor stator and the teeth. The fixing method of the electric motor stator described in 1.
The fan-shaped recess center line is a line that connects a position that is half the circumferential width of the recess and the center of the sector that forms the recess.

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