JP4627002B2 - Manufacturing method of hermetic compressor - Google Patents

Description

  The present invention relates to a method for manufacturing a hermetic compressor used in an air conditioner or the like.

  2. Description of the Related Art In recent years, a permanent magnet type motor using a permanent magnet as a rotor has become the mainstream of compressor motors used in air conditioners and the like for high efficiency. As a method of assembling such a compressor, the rotor and the shaft are fixed while the rotor's permanent magnet is not magnetized, and the rotor is incorporated into the stator, and then the stator winding Some magnetize the permanent magnet of the rotor by passing an electric current through the rotor.

  However, in this method, since a high magnetizing voltage is applied to the stator winding and a large magnetizing current flows, the reliability of the winding may be reduced. In particular, rare-earth magnets having a high magnetic force have become mainstream recently for permanent magnets incorporated in rotors. However, since this rare earth magnet has a high coercive force, the magnetizing voltage and magnetizing current necessary for magnetizing also increase, and there is a higher possibility that the reliability of the stator winding due to magnetization will be reduced. It was.

  In addition, when the winding method of the stator is a concentrated winding method, uneven magnetic flux is generated, so it is necessary to increase the magnetizing current and the number of times of magnetization, and there is a risk that the reliability of the winding may be reduced. .

As a countermeasure against this, there is a method in which a permanent magnet of a rotor is magnetized by a dedicated magnetizing yoke and then the rotor is incorporated into a compressor (for example, see Patent Document 1).
JP 2003-70215 A

  As a method of fixing the rotor to the shaft, there is a method of expanding the diameter of a shaft insertion hole provided in the center portion of the rotor by heating the rotor and inserting the shaft there. As a heating means in this case, it is mainly known to put a rotor in a high temperature bath such as an electric furnace. In this heating method, the temperature of the rotor is heated almost uniformly from the shaft insertion hole to the permanent magnet. However, since the rare earth magnet has a characteristic that the holding power decreases as the temperature increases, there is a problem that when the magnet is heated after magnetization, the permanent magnet is demagnetized when the temperature rises above a certain temperature. When the permanent magnet of the rotor is demagnetized, the performance is deteriorated and the controllability is deteriorated. Therefore, demagnetization cannot be allowed. As a countermeasure, if the heating temperature of the rotor is set low so that the permanent magnet is not demagnetized, there is a problem that the shaft insertion hole cannot be sufficiently expanded and the shaft is poorly inserted.

  As a means for fixing the rotor and the shaft, there is a method in which the rotor is press-fitted without heating. However, in this method, an excessive load is applied to the compression element portion integrated with the shaft, the welded portion where the compression element portion and the sealed container are fixed, and this causes distortion, resulting in reduced performance. Or there was a risk of losing reliability.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a method for manufacturing a hermetic compressor that does not impair performance and reliability.

  A method for manufacturing a hermetic compressor according to the present invention includes an electric element unit including a stator on which windings are provided, and a rotor using a rare earth permanent magnet and having a shaft insertion hole at the center, In a manufacturing method of a hermetic compressor in which a refrigerant is compressed and an electric element part and a compression element part connected by a shaft are accommodated in a hermetic container, the rotor rare earth permanent magnet is magnetized and the rotor shaft is inserted. A heating coil is inserted into the hole, the rotor is heated by induction heating, and the shaft of the compression element is inserted into the shaft insertion hole of the rotor whose diameter has been increased by heating, and is fixed.

According to the method for manufacturing a hermetic compressor of the present invention, even if the shaft insertion hole of the rotor is heated to a temperature at which the shaft can be inserted, the temperature of the permanent magnet becomes lower than that even if the shaft insertion hole of the rotor is heated. There is no magnetism, and it has the effect of preventing deterioration in performance and controllability.
In addition, since the fixing method between the rotor and the shaft is not press-fitting but shrink fitting, there is no distortion in the compression element portion and the like, and performance and reliability can be prevented from being lowered.

Embodiment 1 FIG.
1 to 6 are diagrams showing Embodiment 1, FIG. 1 is a longitudinal sectional view of a hermetic compressor, FIG. 2 is a sectional view of an electric element section in an axis orthogonal direction, and FIG. 3 is an assembly process of the hermetic compressor. FIG. 4 is a diagram showing the heating coil, FIG. 5 is a flowchart showing the assembly process of the hermetic compressor, and FIG. 6 is a diagram showing the temperature transition of the rotor in the heating process.
In FIG. 1, the hermetic compressor accommodates an electric element part 2 and a compression element part 3 in a hermetic container 1. The electric element section 2 is a permanent magnet type electric motor having a stator 4 whose winding method is a concentrated winding method (however, it is not limited to the concentrated winding method, and may be another winding method) and a rotor 5. . The rotor 5 includes a rotor core 6 formed by laminating electromagnetic steel sheets provided with slits (magnet housing holes) for inserting permanent magnets, and a rare earth permanent magnet 7 inserted into the slits. The electric element portion 2 and the compression element portion 3 are connected by a shaft 8. The refrigerant is introduced from the suction pipe 9 into the compression element section 3, and the high-temperature and high-pressure refrigerant gas compressed by the compression element section 3 is discharged from the discharge pipe 10 provided at the upper part of the sealed container 1 to the outside of the sealed container 1. Discharged.

  With reference to FIG. 2, the structure of an example of a permanent magnet type electric motor constituting the electric element portion 2 will be briefly described. The permanent magnet motor has a stator 4 and a rotor 5 fixed to the shaft 8. In the stator 4, a plurality of teeth 4 c are formed in the radial direction on the stator core 4 a (in the example of FIG. 2, nine teeth 4 c), and each tooth 4 c has a concentrated winding winding 4 b. Is given.

  In the rotor 5, magnet housing holes 6a are formed for the number of poles at positions close to the outer periphery of the rotor core 6, and rare earth permanent magnets 7 are housed in the respective magnet housing holes 6a. A shaft 8 is fixed to the center of the rotor 5.

Next, a method for manufacturing a hermetic compressor will be described with reference to FIGS.
First, as shown in FIG. 3A, the rotor 5 is positioned and placed on the conveying pallet 20 (S1 in FIG. 5). Although positioning of the rotor 5 with respect to the transport pallet 20 is not shown, for example, a protrusion provided on the centering portion 21 of the transport pallet 20 and a notch provided in the shaft insertion hole 11 of the rotor 5. And so on.

  Next, as shown in FIG. 3B, a magnetizing dedicated yoke 22 is disposed on the outer periphery of the rotor 5 (S2), and a magnetizing current is passed through the dedicated magnetizing yoke 22 by a magnetizing power source (not shown), The rare earth permanent magnet 7 of the rotor 5 is magnetized (S3).

  Next, as shown in FIG. 3 (c), the heating coil 23 is inserted into the shaft insertion hole 11 of the rotor 5 (S4), and a high frequency current is passed through the heating coil 23 by a power source (not shown) to thereby rotate the rotor 5. Is heated (S5), and the shaft 8 of the compression element portion 3 fixed together with the stator 4 is inserted into the sealed container 1 from above as shown in FIG. (S6). Thereafter, when the rotor 5 is cooled, the shaft insertion hole 11 is reduced in diameter, and the shaft 8 and the rotor 5 are fixed (S7).

  The structure of the heating coil 23 will be briefly described with reference to FIG. FIG. 4 shows a portion to be inserted into the shaft insertion hole 11 of the rotor 5. For example, a coil 23 a is accommodated in a cover 23 b made of Teflon (registered trademark). When a high-frequency current is passed through the coil 23a of the heating coil 23, a magnetic field is generated in the coil 23a in the direction of the shaft insertion hole 11 of the rotor 5, and this magnetic field is chained with the rotor core 6 of the rotor 5 in the axial direction. In exchange, an eddy current flows through the rotor core 6 and the rotor core 6 is heated (this is called induction heating).

  FIG. 6 is a diagram showing the temperature transition of the rotor 5 in the heating process, with the horizontal axis representing time and the vertical axis representing temperature. First, when an electric current is passed through the heating coil 23, the temperature of the shaft insertion hole 11 of the rotor 5 is rapidly increased by induction heating. When the temperature of the shaft insertion hole 11 reaches a certain temperature, the energization is stopped and the shaft 8 is inserted into the next process, and the temperature of the shaft insertion hole 11 decreases during this time. Is set higher than the required temperature when the shaft 8 is inserted.

  On the other hand, since the current passed through the heating coil 23 is a high-frequency current, no eddy current is generated in the rare earth permanent magnet 7 that is farther from the heating coil 23. For this reason, the rare earth permanent magnet 7 does not generate heat directly, and the temperature rises due to heat conduction from the shaft insertion hole 11, so that the temperature gradually rises as shown in FIG. Thereafter, the temperature is saturated where the temperature of the shaft insertion hole 11 and the temperature of the rare earth permanent magnet 7 are suspended. Therefore, the maximum temperature of the rare earth permanent magnet 7 is lower than the temperature required when the shaft 8 is inserted into the shaft insertion hole 11 (the temperature at which the diameter of the shaft 8 must be expanded to insert the shaft 8).

  According to the above assembling method, since the rare earth permanent magnet 7 is magnetized by the dedicated magnetizing yoke 22, and the rotor 5 is fixed to the shaft 8, a large voltage and a large voltage are applied to the winding 4b of the stator 4. No current is applied, and a decrease in reliability of the concentrated winding type winding 4b can be prevented.

  Further, since the heating coil 23 is inserted into the shaft insertion hole 11 provided in the center of the rotor 5 and the rotor 5 is heated by induction heating, the temperature of the rare earth permanent magnet 7 is demagnetized. The shaft 8 and the rotor 5 can be fixed without being raised, and the performance and controllability of the motor can be prevented from deteriorating.

Embodiment 2. FIG.
In the first embodiment, the rotor 5 is heated only once. Next, the rotor 5 is heated twice, that is, the preliminary heating step and the main heating step. 2 will be described.
FIGS. 7 to 9 are diagrams showing the second embodiment, FIG. 7 is a diagram showing the temperature transition of the rotor in the heating process by the conventional heating method, and FIG. 8 is a flowchart showing the assembly process of the hermetic compressor, FIG. 9 is a diagram showing the temperature transition of the rotor in the heating process.

  For example, when it is necessary to increase the fitting allowance between the shaft 8 and the rotor 5 to increase the fixing force between them, the temperature of the shaft insertion hole 11 of the rotor 5 when the shaft 8 is inserted must be increased. Accordingly, it is necessary to increase the maximum temperature of the shaft insertion hole 11 as shown in FIG. However, the electrical steel sheet used for the rotor core 6 changes its mechanical characteristics when the temperature rises above 500 ° C., which is the transformation point. Therefore, if the temperature is raised too much, the reliability may be impaired. .

Therefore, in the present embodiment, the preheating step is introduced before the main heating step. A method for manufacturing a hermetic compressor will be described with reference to FIGS.
First, as in the first embodiment, the rare earth permanent magnet 7 of the rotor 5 is magnetized (S10 in FIG. 8), and the rotor 5 is moved by the heating coil 23 inserted into the shaft insertion hole 11 in the preheating step. It is heated (S11) and left until the temperature of the shaft insertion hole 11 and the temperature of the rare earth permanent magnet 7 are saturated (S12). By this preliminary heating step, the temperature of the entire rotor 5 is maintained at a higher temperature than the pre-heating temperature. Next, the main heating step is performed in this state (S13). At this time, the maximum temperature of the shaft insertion hole 11 is set to a value not exceeding the transformation point of the electrical steel sheet. The shaft 8 of the compression element portion 3 fixed together with the stator 4 in the sealed container 1 is inserted into the expanded shaft insertion hole 11 (S14). Thereafter, when the rotor 5 is cooled, the shaft insertion hole 11 is reduced in diameter, and the shaft 8 and the rotor 5 are fixed (S15).

  As a result, the temperature of the entire rotor 5 is increased by preheating as compared to heating only once, so the maximum temperature of the shaft insertion hole 11 does not change, but the temperature decrease speed during conveyance to the next process is reduced. Slowly (because the amount of heat taken away decreases), the temperature of the shaft insertion hole 11 when the shaft 8 is inserted can be made higher than in the case of heating only once.

  As described above, by performing the heating process of the rotor 5 twice, that is, the preliminary heating process and the main heating process, the shaft insertion hole when the shaft 8 is inserted without increasing the maximum temperature of the shaft insertion hole 11. 11 Since the temperature can be raised, even when the fitting allowance between the rotor 5 and the shaft 8 has to be increased, the mechanical properties of the electromagnetic steel sheet are not impaired in the assembly of the compressor. Reliability degradation can be prevented.

  In this embodiment, the number of times of preliminary heating is set to one, but it may be divided into two or more times.

  In the present embodiment, as a preheating method, the heating coil 23 is inserted into the shaft insertion hole 11 of the rotor 5 to heat the rotor 5. However, the purpose of the preheating is the rotor 5. Since the purpose is to raise the entire temperature slightly, a method of heating in a high temperature bath such as an electric furnace or a method of heating by arranging a heating coil on the outer periphery of the rotor 5 may be used.

Embodiment 3 FIG.
10 and 11 are diagrams showing Embodiment 3, FIG. 10 is a longitudinal sectional view of a rotor, and FIG. 11 is a diagram showing a rotor and a heating coil.
In the first and second embodiments, the diameters of the shaft insertion holes 11 of the rotor 5 are all the same. However, in the present embodiment, as shown in FIG. A large-diameter portion 11a in which the diameter of the end portion in the axial direction is larger than the diameter in the center in the axial direction is provided.

  Even when there are multiple axial lengths of the rotor 5, it is important to improve the operation rate of the assembly line by manufacturing using the same equipment and minimizing setup changes such as jig replacement. It is. For this reason, it is necessary to share the heating coil 23 as well. At this time, the size of the heating coil 23 is matched with that of the rotor 5 having a large axial length (see FIG. 11A).

  When the rotor 5 having a small axial length is heated using the heating coil 23, the heating coil 23 protrudes in the axial direction as shown in FIG. When the rotor 5 is heated in this state, the output of the heating coil 23 is concentrated at the end of the rotor 5 on the side from which the heating coil 23 protrudes (a in the figure), and the temperature of this portion is abnormally high. There is a problem of becoming. As a result, the rare earth permanent magnet 7 may be demagnetized or the mechanical characteristics of the rotor core 6 may be impaired.

  However, as shown in the present embodiment, by providing the large-diameter portion 11a in the shaft insertion hole 11 on the side from which the heating coil 23 protrudes, the heating coil 23 and the shaft are inserted as shown in FIG. Since the distance from the large-diameter portion 11a of the hole 11 is increased, eddy current hardly flows through the large-diameter portion 11a of the shaft insertion hole 11 and the temperature does not increase. At this time, the output of the heating coil 23 is concentrated at the axial end portion (b) in the narrow diameter portion of the shaft insertion hole 11, but there is a portion that is not heated at the upper portion, and absorbs heat. The temperature in the b section will not rise abnormally.

  As described above, according to the present embodiment, when the rotor 5 having different axial lengths is assembled, the rare earth permanent magnet 7 is not demagnetized even if the heating coil 23 is shared. The change can be omitted, and an increase in processing cost can be suppressed.

It is a figure which shows Embodiment 1, and is a longitudinal cross-sectional view of a hermetic compressor. FIG. 5 shows the first embodiment, and is a cross-sectional view of the electric element portion in the direction perpendicular to the axis. It is a figure which shows Embodiment 1, and is a figure which shows the assembly process of a hermetic compressor. It is a figure which shows Embodiment 1, and is a figure which shows the coil for a heating. FIG. 5 is a diagram showing the first embodiment and is a flowchart showing an assembly process of the hermetic compressor. It is a figure which shows Embodiment 1, and is a figure which shows the temperature transition of the rotor in a heating process. It is a figure which shows Embodiment 2, and is a figure which shows the temperature transition of the rotor in the heating process by the conventional heating system. It is a figure which shows Embodiment 2, and is a flowchart figure which shows the assembly process of a hermetic compressor. It is a figure which shows Embodiment 2, and is a figure which shows the temperature transition of the rotor in a heating process. It is a figure which shows Embodiment 3, and is a longitudinal cross-sectional view of a rotor. It is a figure which shows Embodiment 3, and is a figure which shows a rotor and a heating coil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container, 2 Electric element part, 3 Compression element part, 4 Stator, 4a Stator iron core, 4b Winding, 4c Teeth, 5 Rotor, 6 Rotor iron core, 6a Magnet accommodation hole, 7 Rare earth permanent magnet,
8 Shaft, 9 Suction pipe, 10 Discharge pipe, 11 Shaft insertion hole, 11a Large diameter part, 20 Transport pallet, 21 Centering part, 22 Dedicated magnetizing yoke, 23 Heating coil, 23a coil, 23b Cover.

Claims (3)

An electric element portion having a stator to which winding is applied and a rotor using a rare earth permanent magnet and having a shaft insertion hole in the center portion, and compressing the refrigerant and connecting the electric element portion and the shaft In the manufacturing method of the hermetic compressor in which the compressed element part is housed in a hermetic container
Magnetizing the rare earth permanent magnet of the rotor,
As a preheating step, a heating coil is inserted into the shaft insertion hole of the rotor and the rotor is heated by induction heating, and left until the temperature of the shaft insertion hole of the rotor and the permanent magnet is saturated,
As the main heating step, a heating coil is inserted into the shaft insertion hole of the rotor, and the rotor is reheated by induction heating,
The shaft of the compression element portion is heated and expanded and inserted into the shaft insertion hole of the rotor to be fixed,
A method for manufacturing a hermetic compressor, wherein the preliminary heating step is performed at least once. When assembling the rotor having at least one end of the shaft insertion hole of the rotor having a diameter larger than that of the central portion and having different axial lengths, one type of heating coil is used. claim 1 Symbol mounting method of manufacturing a hermetic compressor, characterized in that by inserting a use coil from said radially enlarged to end the shaft insertion hole of the rotor to heat the rotor. The method of manufacturing a hermetic compressor according to claim 1 or 2, wherein the stator winding method is a concentrated winding method.

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