JP5047530B2 - Electric motor - Google Patents

Description

  The present invention relates to a technique for improving the efficiency of an electric motor, and more particularly to an electric motor in which an iron core is fixed to a pedestal by fixing means such as a bolt.

  In recent years, there has been a demand for improved efficiency of various electric devices from the viewpoint of energy saving. Although the efficiency of electrical equipment is affected by various factors, iron loss, which is a loss generated in the iron core of an electric motor, occupies a relatively large specific gravity. Therefore, recently, electrical steel sheets with lower iron loss are used. Has increased.

  Using such an electromagnetic steel sheet, the stator for an electric motor that is integrally punched into the shape of the stator, laminated, passed through a bolt hole that is processed at the time of punching, and fixed to the pedestal, Magnetic characteristics such as iron loss of the stator are deteriorated (see FIG. 1).

  As a technique for reducing the stress generated in such a stator, there is Patent Document 1 disclosed by a part of the present inventors. This technology reduces local stress generated near the bolt fixing part when fixing the bolt by pressing the stator uniformly using an annular fixing plate when fixing the stator to the pedestal. It is a technology that suppresses the increase in iron loss.

  Further, Patent Document 2 relates to a stator of a generator, in order to prevent deterioration of an insulating layer based on a difference in thermal expansion due to a temperature rise during operation of the stator core and the stator coil. An invention is disclosed in which the linear expansion coefficient of a metal duct spacer for securing a flow path of a cooling medium in the core is larger than the linear expansion coefficient of a silicon steel plate (stator core).

JP-A-2005-304106 JP 11-234929 A How to use a brushless DC motor Ohm Co., Ltd. issued on July 10, 2003 ISBN4-274-03601-4

  However, the stress generated inside the stator is not only due to the fixing method, but also due to heat generated during operation. For example, the heat generated by the winding during operation is large, and this heat is dissipated to the refrigerant in a compressor whose atmosphere, particularly the periphery, is filled with the refrigerant. At this time, the temperature of the stator and the base rises due to heat transfer from the coil and heat transfer from the atmosphere. Since the stator expands due to this heat, if an imbalance occurs between the expansion of the stator and the pedestal, stress is generated inside the stator.

In particular, in an electric motor in which a stator 13 as shown in FIG. The stress becomes a problem. In general, in the electric motor of the above form, the base 14 is made of low alloy cast iron and has a linear expansion coefficient of 10 to 12 [ × 10 ⁻⁶ / ° C.], and is a non-oriented electrical steel sheet that is often used in home appliances such as air conditioners and refrigerators. The linear expansion coefficient is about the same or smaller than 12 to 13 [ × 10 ⁻⁶ / ° C.]. In general, since the stator directly touches the winding, the temperature is higher than that of the pedestal. Therefore, the stator has a larger expansion amount than the pedestal. In that case, the stator 13 tries to expand according to the temperature. However, if the stator 13 is firmly fixed to the pedestal 14, the expansion amount of the pedestal 14 is small, so that the expansion of the stator 13 is inhibited. At this time, a strong compressive stress is partially generated inside the stator 13, and the technique described in Patent Document 1 does not improve magnetic characteristics such as iron loss of the stator.

Although an example in which an aluminum alloy is applied to the pedestal is also seen, the linear expansion coefficient of the aluminum alloy is too large, about 23 [ × 10 ⁻⁶ / ° C.], conversely, the amount of expansion of the pedestal increases, In part, compressive stress is generated.

  In addition, the invention disclosed in Patent Document 2 is intended to prevent the breakdown of the insulating layer, and has a problem that there is no effect of reducing the compressive stress generated inside the stator.

  An object of the present invention is to propose a stator for an electric motor with low iron loss by making the linear expansion coefficient of the pedestal appropriate for the linear expansion coefficient of the stator fixed to the pedestal with bolts or holding rings. To do.

  In order to solve the above problems, the gist of the present invention is as follows.

( 1 ) It has a stator and a rotor in which a plurality of electromagnetic steel sheets are laminated, and the stator is arranged on the outside and the rotor is arranged on the inside around the rotation axis, and the stator is composed of a holding ring and a pedestal. The stator, the rotor, and the pedestal are fixed to each other, and the case is surrounded by a case, and in the compressor electric motor filled with the refrigerant, the pedestal linear expansion coefficient αc [× 10 ⁻⁶ / ° C. ] Is divided by the linear expansion coefficient αs [× 10 ⁻⁶ / ° C.] of the stator, αc / αs is greater than 1.25 and less than 1.35,
The above pedestals are in mass%, C: 1.00-3.30%, Si: 1.00-2.00%, Mn: 0.35-1.50%, Ni: 5.00-70.00 %, Cr: 0.10~5.50%, Cu : contains 0.01 to 20.00%, the motor you and the balance of iron and unavoidable impurities.

( 2 ) It has a stator and a rotor in which a plurality of electromagnetic steel sheets are laminated, and the stator is arranged on the outside and the rotor is arranged on the inside around the rotation axis. The stator, the rotor, and the pedestal are fixed to each other, and the case is surrounded by a case, and in the compressor electric motor filled with the refrigerant, the pedestal linear expansion coefficient αc [× 10 ⁻⁶ / ° C. ] Is divided by the linear expansion coefficient αs [× 10 ⁻⁶ / ° C.] of the stator, αc / αs is greater than 1.25 and less than 1.35,
The pedestal is, by mass%, 2.80 to 3.00%, Si: 1.20 to 1.90%, Mn: 0.40 to 1.10%, Ni: 13.00 to 22.00%, cr: 0.01~1.70%, Cu: contains 0.01 to 0.05 percent, motor you and the balance of iron and unavoidable impurities.

(3) Furthermore, the pressing ring (1) or (2) above characterized by comprising the components described (1) or (2) The electric motor according.

(4) the refrigerant, HFC, CO _2, ammonia, isobutane, butane, propane, above, characterized in that consist of any one or more cyclopropane (1) to the electric motor according to any one of (3) .

  According to the present invention, the iron loss of the electric motor can be reduced by 10% or more as compared with a conventional electric motor using a stator made of a low alloy cast iron and fixed with a low alloy cast iron holding ring. The iron loss of the motor can be reduced by 14% or more compared to an electric motor using a stator fixed to an aluminum pedestal with an aluminum holding ring.

As shown in FIG. 3, the present inventors are filled with a refrigerant such as HFC (hydrofluorocarbon), CO ₂ , ammonia, isobutane, butane, propane, cyclopropane, etc. A plurality of stacked stators 6 and a rotor 12 are provided, the stator 6 is arranged on the outside and the rotor 12 is arranged on the inside around the rotation axis, and the stator 6 is mounted on a base 7 with bolts 8 and a holding ring 9. In the electric motor fixed by, using a stator molded from electromagnetic steel sheet and a pedestal machined from five types of cast iron and one type of aluminum alloy, tests were performed under the same operating conditions, and the iron loss of the stator was measured. did. The types of pedestals and the linear expansion coefficient are as shown in Table 1, and the linear expansion coefficient of the electrical steel sheet forming the used stator is 13 [ × 10 ⁻⁶ / ° C.]. The operating conditions were continuous operation for 1 hour at 75 rpm and 10 Nm.

  The iron loss is measured immediately after 1 hour of continuous operation, the output value calculated from the input power at 75 rpm × 10 Nm, the amount of heat generated in the winding 10 calculated as current × voltage, and the bearing 11 measured in advance. It was defined as the value obtained by subtracting the mechanical loss caused by Further, after the test, the electric motor was left to room temperature and then continuously operated for 1 hour at a high load of 75 rpm and 15 Nm, and the iron loss was measured in the same manner as described above.

  The result is shown in FIG. On the vertical axis, evaluation was made by dividing the measured iron loss of the stator, called the building factor, by the iron loss value of the magnetic steel sheet alone. From other experiments including this result, it is possible to reduce the iron loss of the stator when the relationship expressed by the following equation (1) holds between the linear expansion coefficient αc of the pedestal and the linear expansion coefficient αs of the stator. I found.

1.05 <αc / αs <1.5 (1)
Depending on the operating conditions, the temperature of the stator and pedestal varies, but a sufficiently good iron loss value can be obtained within the range of the above formula. Further, from this result, it was found that the linear expansion coefficient of the pedestal needs to be in the range of 15 to 19.5 [ × 10 ⁻⁶ / ° C.]. In order to obtain a better iron loss value, it is desirable that the value of αc / αs satisfies the equation (2).

  1.25 <αc / αs <1.35 (2)

Moreover, a base is the mass%, C: 1.00-3.30%, Si: 1.00-2.00%, Mn: 0.35-1.50%, Ni: 5.00-70. It is preferably a cast iron containing 00%, Cr: 0.10 to 5.50%, Cu: 0.01 to 20.00%, and the balance iron and inevitable impurities. If each component is within this range, can manufacturing operation cast iron pedestal satisfy the formula (1), preferable.

Furthermore, the components of the pedestal cast iron are limited, and in terms of mass%, 2.80 to 3.00%, Si: 1.20 to 1.90%, Mn: 0.40 to 1.10%, Ni: 13.00. The linear expansion coefficient is 16.22.00%, Cr: 0.01-1.70%, Cu: 0.01-0.05%, and the linear expansion coefficient is 16. 3 to 17.5 [ × 10 ⁻⁶ / ° C.], which satisfies the formula (2), which is preferable.

  In addition, it is more preferable that the component of the pressing ring is in the same range as the component range of the pedestal because the constraints on the upper and lower surfaces of the stator are uniform.

As shown in FIG. 3, in the electric motor in which the inside is filled with the refrigerant (HFC), surrounded by the case 5, and the stator 6 is fixed to the pedestal 7 with the bolts 8 and the holding ring 9, the pedestal 7 and the holding ring 9 are made of nickel. And a high alloy cast iron containing a relatively large amount of copper (linear expansion coefficient: 17.1 [ × 10 ⁻⁶ / ° C.], components are shown in Table 2), an electric motor was prepared. Next, for comparison, the pedestal 2 and the holding ring 4 are made of low alloy cast iron (linear expansion coefficient 11.2 [ × 10 ⁻⁶ / ° C.], components are shown in Table 2) and aluminum. What was prepared by (linear expansion coefficient 23.0 [ × 10 ⁻⁶ / ° C.]) was prepared. A magnetic steel sheet having a linear expansion coefficient of 13.0 [ × 10 ⁻⁶ / ° C.] was used. The operating conditions were continuous operation for 1 hour at 75 rpm and 10 Nm. The iron loss is measured immediately after continuous operation for 1 hour with the output value calculated from the input power at 75 rpm x 10 Nm, the amount of heat generated in the winding calculated by the current x voltage, and the bearing measured in advance. It was defined as the value obtained by subtracting the resulting mechanical loss.

As a result, the iron loss of the stator in the electric motor using the high alloy cast iron base having the linear expansion coefficient of 17.1 [ × 10 ⁻⁶ / ° C.] and the retaining ring according to the present invention is 3.63 [W / kg]. And an aluminum base with a linear expansion coefficient of 23.0 [ × 10 ⁻⁶ / ° C.] and a low alloy cast iron base with a linear expansion coefficient of 11.2 [ × 10 ⁻⁶ / ° C.] and a holding ring An iron loss of 14% lower than that of the holding ring was obtained.

  Furthermore, the winding method was the same as that described above, whether it was distributed winding as introduced on page 46 of Non-Patent Document 1 or concentrated winding.

The figure which shows the residual stress dependence of an iron loss. The schematic diagram of a general electric motor. Sectional drawing of the electric motor which shows the form of this invention, and this invention. The figure which shows the relationship of the iron loss of a stator, and the ratio of the linear expansion coefficient of a stator and a base.

Explanation of symbols

1 Dependence of iron loss on residual stress at magnetic flux density of 0.7 T 2 Dependence of iron loss on residual stress at magnetic flux density of 1.0 T 3 Dependence of iron loss on residual stress at magnetic flux density of 1.3 T 4 Iron at magnetic flux density of 1.5 T Residual Stress Dependence of Loss 5 Electric Motor Case Showing the Form of the Present Invention and the Present Invention 6 Stator of the Motor Presenting the Form of the Present Invention and the Present Invention 7 Base of the Motor Presenting the Present Form and the Present Invention 8 Motor Bolts Showing Forms and Present Inventions 9 Forms of the Present Invention and Holding Rings of Motors Presenting the Present Inventions 10 Forms of the Present Invention and Windings of Motors Presenting the Present Inventions 11 Motor Bearings Presenting the Present Forms and the Present Inventions 12 A rotor of an electric motor according to the present invention and the present invention 13 A stator of a general motor 14 A base of a general motor 15 A holding ring 16 of a general motor General electric motor bolt

Claims (4)

It has a stator and a rotor in which a plurality of electromagnetic steel plates are laminated, and the stator is arranged outside and the rotor is arranged inside around a rotation axis, and the stator is fixed between a holding ring and a base. The stator, the rotor, and the pedestal are surrounded by a case, and in the electric motor in which the case is filled with refrigerant, the pedestal has a linear expansion coefficient αc [× 10 ⁻⁶ / ° C.]. The value αc / αs divided by the linear expansion coefficient αs [× 10 ⁻⁶ / ° C.] is greater than 1.25 and less than 1.35,
The above pedestals are in mass%, C: 1.00-3.30%, Si: 1.00-2.00%, Mn: 0.35-1.50%, Ni: 5.00-70.00 %, Cr: 0.10~5.50%, Cu : contains 0.01 to 20.00%, the motor you and the balance of iron and unavoidable impurities. It has a stator and a rotor in which a plurality of electromagnetic steel plates are laminated, and the stator is arranged outside and the rotor is arranged inside around a rotation axis, and the stator is fixed between a holding ring and a base. The stator, the rotor, and the pedestal are surrounded by a case, and in the electric motor in which the case is filled with refrigerant, the pedestal has a linear expansion coefficient αc [× 10 ⁻⁶ / ° C.]. The value αc / αs divided by the linear expansion coefficient αs [× 10 ⁻⁶ / ° C.] is greater than 1.25 and less than 1.35,
The above pedestals are in mass%, C: 2.80 to 3.00%, Si: 1.20 to 1.90%, Mn: 0.40 to 1.10%, Ni: 13.00 to 22.00. %, Cr: 0.01~1.70%, Cu : containing from .01 to 0.05%, the motor you and the balance of iron and unavoidable impurities. Furthermore, the electric motor according to claim 1 or 2, characterized in that the pressing ring consists element of claim 1 or 2, wherein. The refrigerant, HFC, CO _2, ammonia, isobutane, butane, propane, electric motor according to any one of claim 1 to 3, characterized in that it consists of any one or more cyclopropane.

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