Motor for electric compressor and electric compressor comprising same

Abstract

[Problem] To provide a motor for an electric compressor that makes it possible to suppress a decrease in life of an insulator, and an electric compressor comprising said motor. [Solution] The motor for an electric compressor comprises stator core, an insulator that is in contact with the core, and a winding that is wound around the insulator. The insulator is made of a resin material having a relative permittivity of 3.7 or less and a dielectric loss tangent of 0.0004 or less.

Description

Motor for electric compressor and electric compressor equipped with same

[0001] The present invention relates to a motor for an electric compressor in which a winding is wound around an insulator attached to a core of a stator, and to an electric compressor including the motor.

[0002] Conventionally, a motor for driving a compression element of an electric compressor is composed of a stator and a rotor that rotates on the stator side. The stator is configured with a core formed with multiple teeth, each of which is fitted with an insulator with a winding (see Patent Document 1). It has also been proposed to use polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT) as the material for the insulator (see Patent Document 2).

[0003] JP 2018-126009 A JP 2000-274360 A

[0004] However, in the conventional techniques including those disclosed in Patent Documents 1 and 2, there is room for further improvement in terms of suppressing the shortening of the life of the insulator.

[0005] An object of the present invention is to provide a motor for an electric compressor that can suppress a decrease in the lifespan of an insulator, and an electric compressor including the motor.

[0006] As a result of extensive research, the inventors have found that when a resin having a relative permittivity and a dielectric loss tangent that satisfy specific conditions is used for an insulator, the shortening of the insulator's lifespan can be significantly suppressed, and have thus completed the present invention. According to the present invention, the following electric compressor motors and the like can be provided.

[0007] According to one aspect of the present invention, there is provided a motor for an electric compressor, comprising a stator core, an insulator in contact with the core, and a winding wound around the insulator, the insulator being made of a resin material having a relative permittivity of 3.7 or less and a dielectric loss tangent of 0.0004 or less. The motor for an electric compressor according to this aspect can suppress a decrease in the life of the insulator.

[0008] More preferably, the temperature rise of the insulator due to vibration is 1.5° C. or less, thereby more suitably suppressing a decrease in the life span of the insulator.

[0009] More preferably, the resin material contains syndiotactic polystyrene, which can more suitably suppress a decrease in the life span of the insulator.

[0010] According to one aspect of the present invention, there is provided an electric compressor including the electric compressor motor according to one aspect of the present invention. The electric compressor according to this aspect can suppress a decrease in the life of the insulator.

[0011] According to the present invention, it is possible to provide a motor for an electric compressor that can suppress a decrease in the lifespan of an insulator, and an electric compressor including the motor.

[0012] It is a longitudinal sectional side view of an electric compressor according to an embodiment of the present invention, which is equipped with an electric compressor motor according to an embodiment of the present invention. It is an exploded perspective view of a stator. It is a perspective view of a stator. It is a diagram illustrating vibration of an insulator.

[0013] The electric compressor motor and the electric compressor equipped with the motor of the present invention will be described in detail below. In this specification, "x to y" represents a numerical range of "greater than or equal to x and less than or equal to y." The upper and lower limits of the numerical ranges can be combined arbitrarily. Furthermore, among the individual embodiments of the aspects of the present invention described below, two or more embodiments that are not mutually exclusive can be combined, and an embodiment combining two or more embodiments is also an embodiment of the aspects of the present invention.

[0014] An electric compressor motor according to one aspect of the present invention includes a stator core, an insulator attached to the outer surfaces of the teeth of the core, and a winding wound around the outer surface of the insulator, the insulator being made of a resin material having a relative permittivity of 3.7 or less and a dielectric loss tangent of 0.0004 or less. An electric compressor according to another aspect of the present invention includes the electric compressor motor according to another aspect of the present invention. These electric compressor motors and electric compressors have the advantage of being able to suppress a decrease in the lifespan of the insulator.

[0015] The reason for the above-described effect is not entirely clear, but is presumed to be as follows. In an electric compressor motor, vibrations occur in the insulator (the reason for vibration will be described later). During use of the electric compressor, the insulator is subjected to high temperatures (e.g., approximately 150°C), and this vibration can further increase the temperature of the insulator. Conventionally, no technology has been established to suppress the lifespan reduction caused by temperature increases associated with such vibrations. In response, the inventors discovered that the lifespan reduction can be suppressed by including an insulator made of a resin having a relative permittivity of 3.7 or less and a dielectric dissipation factor of 0.0004 or less. More specifically, these electrical property parameters (relative permittivity and dielectric dissipation factor) were found to be extremely effective in suppressing heat generation (temperature increase) associated with physical (macro) vibrations. As a result, the temperature increase in the insulator is suppressed, thereby favorably suppressing the lifespan reduction.

[0016] In one embodiment, the insulator has a temperature rise due to vibration of 1.5°C or less, 1.4°C or less, 1.3°C or less, 1.2°C or less, 1.1°C or less, 1.0°C or less, 0.9°C or less, 0.8°C or less, 0.7°C or less, 0.6°C or less, 0.5°C or less, 0.4°C or less, 0.3°C or less, 0.2°C or less, or 0.1°C or less. The lower limit is not particularly limited and may be, for example, 0.0°C. The lower the temperature rise due to vibration, the more pronounced the effect of suppressing a decrease in life span. Note that the "temperature rise due to vibration" is a value measured by the method described in the examples.

[0017] In one embodiment, the insulator has a lifespan reduction rate due to temperature rise caused by vibration of 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less. The lower limit is not particularly limited and may be, for example, 0%. The "lifespan reduction rate due to temperature rise caused by vibration" is a value measured by the method described in the examples.

[0018] The resin material constituting the insulator may include a resin having a relative permittivity of 3.7 or less and a dielectric dissipation factor of 0.0004 or less. Examples of resins that satisfy these conditions include, but are not limited to, syndiotactic polystyrene and polycarbonate. In one embodiment, the insulator contains syndiotactic polystyrene. Syndiotactic polystyrene is a polystyrene having a syndiotactic structure. A syndiotactic structure is a thermoplastic crystalline resin having a three-dimensional structure in which phenyl groups, which are side chains, are regularly arranged in opposite directions to a main chain formed from carbon-carbon bonds. Methods for producing syndiotactic polystyrene are described in, for example, JP 62-104818 A. Furthermore, a commercially available product such as Xalec (registered trademark) manufactured by Idemitsu Kosan Co., Ltd. may be used.

[0019] The resin material may contain only resins having a dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less, or may contain resins that do not satisfy these conditions (i.e., one or both of the dielectric constant and the dielectric dissipation factor do not satisfy these conditions) in combination (e.g., as a polymer alloy). In one embodiment, 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.9% by mass or more, or 100% by mass of the resin contained in the resin material constituting the insulator is a resin having a dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less. This more significantly reduces the effect of suppressing a reduction in lifespan. In one embodiment, the proportion of resins contained in the resin material constituting the insulator that do not satisfy the conditions of a relative dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less (e.g., one or more resins selected from the group consisting of polyamide 66, polybutylene terephthalate, polyarylene sulfide (e.g., polyphenylene sulfide), and liquid crystal polymers) is 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less. This more significantly exhibits the effect of suppressing a decrease in lifetime. It is preferable that the resins contained in the resin material constituting the insulator consist solely of resins having a relative dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less. This more significantly exhibits the effect of suppressing a decrease in lifetime. In addition, the insulator manufacturing process can be simplified, resulting in improved production efficiency. Furthermore, when the resin contained in the resin material constituting the insulator contains a high concentration of syndiotactic polystyrene (for example, 75 mass% or more), more preferably when the resin consists solely of syndiotactic polystyrene, not only is the effect of suppressing a decrease in lifespan more pronounced, but the weight of the insulator can also be reduced.

[0020] The resin material constituting the insulator may or may not contain components other than resin. Examples of components other than resin include fillers such as glass fiber and additives such as flame retardants (bromine-based, phosphorus-based, etc.). In one embodiment, 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.9% by mass or more, or 100% by mass of the insulator is resin.

[0021] The present invention will be described in more detail below with reference to the drawings. Fig. 1 is a vertical cross-sectional side view of an electric compressor 1 according to an embodiment of the present invention, which is equipped with an electric compressor motor 4 according to an embodiment of the present invention. Fig. 2 is an exploded perspective view of a stator 21 of the electric compressor motor 4. Fig. 3 is a perspective view of the stator 21.

[0022] 1 illustrates a scroll-type electric compressor 1. The electric compressor 1 includes a container 2, a scroll compression element 3 as an example of a compression element, and an electric compressor motor 4 housed therein.

[0023] The scroll compression element 3 comprises a fixed scroll 6 fixed to the container 2 and a movable scroll 7 that revolves without rotating relative to the fixed scroll 6 by a rotary shaft 8 of the electric compressor motor 4. A spiral wrap 11 formed on the fixed scroll 6 and a spiral wrap 12 formed on the movable scroll are arranged to mesh with each other.

[0024] Refrigerant is introduced into the container 2 through a refrigerant inlet passage (not shown). The refrigerant is drawn from the outside into the compression chamber defined between the wraps 11 and 12. The compression chamber narrows toward the center due to the orbital motion of the movable scroll 7, so the drawn refrigerant is compressed and discharged from the center through the discharge chamber 14 and a refrigerant discharge passage (not shown). Furthermore, because the pressure inside the container 2 is low, the refrigerant also passes around the electric compressor motor 4, cooling the electric compressor motor 4.

[0025] The electric compressor motor 4 is a permanent magnet synchronous motor, and is composed of a stator 21 consisting of a core 22 and windings 23, and a magnet-embedded rotor 24 (made of multiple laminated electromagnetic steel plates) that is fixed to the rotating shaft 8 and rotates inside the stator 21.

[0026] The core 22 of the stator 21 is cylindrical. This core 22 is made by laminating and bonding multiple electromagnetic steel sheets. A plurality of teeth 27 (the number of which corresponds to the number of poles; in this example, 12) are provided inside the core 22.

[0027] The winding 23 is wound around insulators (bobbins) made of insulating material (first insulator 33 a and second insulator 33 b in this example). Specifically, the winding 23 is wound around these insulators 33 a, 33 b so as to span between a winding portion 37 a of the first insulator 33 a arranged on one side (here, the upper side) of the core 22 and a winding portion 37 b of the second insulator 33 b arranged on the other side (here, the lower side) of the core 22.

[0028] Between the first insulator 33a and the second insulator 33b, the winding 23 is housed between the teeth 27, 27 of the core 22. An insulation film (not shown) is provided on the surface of the core 22 between the teeth 27, 27 (the surface that may come into contact with the winding 23), thereby ensuring insulation. A magnetic path is formed in this manner. It is assumed that each winding 23 is wired to form a predetermined electric circuit.

[0029] As described above, in this embodiment, in the motor 4 for an electric compressor, which includes the core 22 of the stator 21, the insulators (in this example, the first insulator 33a and the second insulator 33b) in contact with the core 22, and the windings 23 wound around the insulators, the insulators are made of a resin material having a relative dielectric constant of 3.7 or less and a dielectric loss tangent of 0.0004 or less. This makes it possible to suppress a decrease in the lifespan of the insulators.

[0030] This will be explained with reference to FIG. 4 . FIG. 4 is a diagram illustrating insulator vibration and is an enlarged cross-sectional view of the contact portion between the first insulator 33a and the core 22. The first insulator 33a contacts the upper portion of the core 22. Although not shown in FIG. 4 , the second insulator 33b contacts the lower portion of the core 22. These insulators 33a and 33b are pressed against each other toward the core 22 by the winding 23 wound thereon. Electric compressor motors are often used in vibration-generating environments, such as in the engine compartment of an automobile. Therefore, vibration occurs in the insulators 33a and 33b. In contrast, by using a resin material with a relative permittivity of 3.7 or less and a dielectric dissipation factor of 0.0004 or less, heat generation (temperature rise) due to vibration can be suppressed, as described above. As a result, the lifespan of the insulators is reduced. In particular, stress tends to concentrate in the area of ​​the insulator indicated by the symbol P (the outer peripheral area at the bottom of the winding portion 37a). However, even if such stress concentrates, the reduction in the lifespan of the insulator is suppressed, and the inherent strength of the resin material is suitably demonstrated over the long term, making it less likely for insulation breakdown to occur (improving insulation reliability).

[0031] In the above description, the insulator is mainly composed of the first insulator 33 a and the second insulator 33 b (i.e., composed of two independent members), but this is not limiting. The insulator may be composed of, for example, a single member. In this case, for example, the first insulator 33 a and the second insulator 33 b may be integrally connected by a connecting portion (not shown).

[0032] In the above description, the manufacturing method of the insulator is not particularly limited, and the insulator can be manufactured by, for example, injection molding the above-mentioned resin material. Furthermore, the shapes and configurations of the components constituting the electric compressor, such as the insulator and core, are not limited to the shapes and configurations described above, and may be any known shape and configuration.

[0033] Although the above description has been given mainly on the case where the electric compressor is a scroll electric compressor, the present invention is not limited to this. However, the electric compressor motor according to one aspect of the present invention can be suitably used for various electric compressors, such as rotary electric compressors.

[0034] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0035] 1. Resin Material for Insulator Example 1 As a resin material, syndiotactic polystyrene (abbreviated as "SPS", manufactured by Idemitsu Kosan Co., Ltd., Xalec (registered trademark) S136) was prepared.

[0036] Example 2 In Example 1, polycarbonate (abbreviated as "PC", manufactured by Teijin Limited, Panlite (registered trademark) AM-1300E) was prepared in place of the syndiotactic polystyrene.

[0037] Comparative Example 1 In Example 1, polyamide 66 (abbreviated as "PA66", manufactured by BASF, Ultramid (registered trademark) A3HG6) was prepared in place of the syndiotactic polystyrene.

[0038] Comparative Example 2 In Example 1, polybutylene terephthalate (abbreviated as "PBT", manufactured by Polyplastics Co., Ltd., DURANEX (registered trademark) 330LC) was prepared in place of the syndiotactic polystyrene.

[0039] Comparative Example 3 In Example 1, polyphenylene sulfide (abbreviated as "PPS", manufactured by Polyplastics Co., Ltd., DURAFIDE (registered trademark) 1140A6) was used in place of the syndiotactic polystyrene.

[0040] Comparative Example 4 In Example 1, a liquid crystal polymer (abbreviated as "LCP", manufactured by Ueno Pharmaceutical Co., Ltd., UENO LCP 5030G) was prepared in place of the syndiotactic polystyrene.

[0041] 2. Measurement of Relative Dielectric Constant and Dielectric Loss Tangent The relative dielectric constant and dielectric loss tangent of the resin materials prepared in each of the Examples and Comparative Examples were measured under the following measurement conditions. The results are shown in Table 1. <Measurement Conditions> - Compliant with JIS C 2138 (automatic balancing bridge method) - Sample dimensions: 50 × 30 × t3 (mm) - Measurement environment: 23°C, 50% RH - Electrode dimensions: Main electrode diameter φ14 mm, annular electrode inner diameter φ16 mm - Frequency: 100 Hz - Electrode material: Conductive silver paint was used in Example 1 and Comparative Examples 1 to 4, and tin foil was used in Example 2. - Number of measurements: n = 2 - Measurement device: Precision LCR meter E4980A (manufactured by Agilent Technologies)

[0042]

[0043] 3. Vibration Test The resin materials prepared in each of the Examples and Comparative Examples were subjected to a cantilever bending vibration fatigue test in accordance with JIS K 7118 and JIS K 7119. The test conditions were as follows. <Test Conditions> Testing machine: Repeated vibration fatigue tester, B-50, manufactured by Toyo Seiki Seisakusho (1 mm spacers were used for the fixed and movable parts). Stress conditions: Tests were carried out at a stress value that resulted in a strain of 0.2 for each material. Test environment: 23°C, 50% RH Test frequency: 30 Hz (fixed) Stress ratio: R = -1 (reversed)

[0044] In the above test, the temperature of the test piece (made of a resin material) was measured immediately after the start of vibration. A radiation temperature sensor (specifically, Keyence FT-H40K, NR-500, NR-HA08, and FT-50) was used to measure the temperature. The temperature rise of the test piece during the test is shown in Table 2. This temperature rise is the value obtained by subtracting the temperature at the start of vibration from the temperature one hour after the start of vibration. The temperature remained constant one hour after the start of vibration. Table 2 also shows the sum of the operating temperature of the electric compressor (assumed to be 150°C) and the temperature rise (corresponding to the actual operating temperature), the predicted lifespan (assumed to be 1,000 hours at 150°C), and the rate of decrease in lifespan due to temperature increase. The predicted lifespan was calculated based on the 10°C doubling rule. The 10°C doubling rule is expressed by the following formula and is an empirical rule that states that, for example, a 10°C increase in temperature doubles the speed of deterioration and lifespan (deterioration doubles). In the following formula, L is the predicted life, L ０ is the actual temperature (here, 1000 hours), T is the estimated temperature (here, the sum of the operating temperature of the electric compressor and the temperature rise), T ０ is the measured temperature (here, 150°C).

[0045]

[0046]

[0047] From Tables 1 and 2, it can be seen that when a resin material having a relative dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less is used as the resin material for an insulator, the temperature rise caused by vibration is significantly suppressed and the original lifespan is maintained favorably.

[0048] The motor for an electric compressor of the present invention can be suitably used in an electric compressor that is installed in an environment where vibrations may occur, such as the engine compartment of an automobile.

[0049] 1: Electric compressor 2: Container 3: Scroll compression element 4: Motor for electric compressor 6: Fixed scroll 7: Orbiting scroll 8: Rotating shaft 11, 12: Wrap 14: Discharge chamber 21: Stator 22: Core 23: Winding 24: Rotor 27: Teeth 33a: (First) insulator 33b: (Second) insulator 37a, 37b: Winding portion

Claims

1. A motor for an electric compressor comprising a stator core, an insulator in contact with the core, and a winding wound around the insulator, wherein the insulator is made of a resin material with a relative dielectric constant of 3.7 or less and a dielectric dissipation factor of 0.0004 or less.

2. The motor for an electric compressor according to claim 1, wherein the temperature rise of the insulator due to vibration is 1.5°C or less.

3. The motor for an electric compressor according to claim 1 or 2, wherein the resin material includes syndiotactic polystyrene.

4. An electric compressor equipped with the motor for an electric compressor according to claim 1.

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