JP2004251173A - Compressor with closed type motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress heating of a rotor by utilizing a part of a refrigerant sucked by a compressor, in a compressor with a closed type electric motor. <P>SOLUTION: In the compressor A with a closed type electric motor, a compressor 40 and an electric motor 53 for driving the electric motor are juxtaposed on a rotary shaft 30 supported by a closed container 10. The electric motor comprises a stator 55 fixed at the closed container; a rotor 70 having a permanent magnet 75 and revolvably supported at the closed container; and magnet cooling means 50 and 85 to gasify liquid refrigerant, fed from the opposite side in an axial direction of the compressor, and cause it to flow within the rotor toward the compressor and cool a permanent magnet. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hermetic motor-equipped compressor having a hermetic motor, and particularly to cooling of a rotor thereof.
[0002]
[Prior art]
BACKGROUND ART In a refrigeration cycle of an air conditioner system at home or the like, a compressor that compresses a liquid refrigerant into a gas refrigerant is rotationally driven by an electric motor. When a large load is applied to the electric motor, the rotor generates heat, and it is convenient to use a part of the refrigerant compressed by the compressor in order to suppress a rise in temperature. In consideration of this, from the viewpoint, the compressor and the electric motor are brought close to each other, and a part of the refrigerant drawn into the compressor is guided into the electric motor to cool the rotor.
[0003]
In the first conventional example, a compressor and an electric motor are provided coaxially, and refrigerant is sucked from a portion of the electric motor on the compressor side. In other words, the refrigerant suction port is provided at an axially intermediate portion between the juxtaposed compressor and the electric motor. However, in this case, most of the sucked refrigerant flows from the suction port to the compressor, and is not supplied much to the electric motor. Therefore, it cannot be said that the electric motor is sufficiently cooled by the refrigerant.
[0004]
On the other hand, in a second conventional example (see Patent Document 1), after a motor and a compressor are juxtaposed, refrigerant is sucked from a suction port formed at an end of the motor opposite to the compressor. , And feeds in the motor in the axial direction toward the compressor.
[0005]
[Patent Document 1]
JP 2001-173567 A
[Problems to be solved by the invention]
According to the second conventional example, the sucked refrigerant flows in the electric motor in the axial direction, and can theoretically cool the rotor at that time. However, the gap between the inner peripheral surface of the stator fixed to the housing and the outer peripheral surface of the rotor rotatably supported by the housing in the electric motor is very narrow (about 0.5 to 1 mm). Therefore, in reality, the suction resistance of the refrigerant is large and only a small amount of the refrigerant can flow through the gap, and it is hardly sufficient for cooling the rotor.
[0007]
In addition, a large suction device is required to suck an effective amount of refrigerant for cooling the rotor. Not only that, the amount of refrigerant sucked into the compressor is reduced by that amount, and the COP of the refrigeration cycle including the compressor is reduced.
[0008]
The present invention has been made in view of the above circumstances, and provides a hermetic motor-equipped compressor that can effectively suppress heat generation of a rotor by utilizing a part of refrigerant sucked into the compressor. Aim.
[0009]
[Means for Solving the Problems]
The inventor of the present application has conceived that the refrigerant sucked from the anti-compressor side flows through the inside of the rotor instead of flowing through the gap between the stator and the rotor as in the second embodiment. Thus, the present invention has been completed.
[0010]
In the hermetic type compressor with an electric motor according to the present invention, as described in claim 1, the compressor, the compressor and the electric motor for driving the compressor are arranged side by side on a rotating shaft supported by the hermetic container. . Here, the electric motor gasifies a liquid refrigerant supplied from the opposite side of the compressor in the axial direction, with a stator fixed to the closed container, a rotor having a permanent magnet and rotatably supported by the closed container. And a magnet cooling unit that circulates through the rotor toward the compressor and cools the permanent magnet.
[0011]
In this hermetic motor-equipped compressor, when the cooling load for cooling by the refrigeration cycle is large, liquid refrigerant is supplied to the rotor from the magnet cooling means. The supplied liquid refrigerant is gasified and cools the permanent magnet when flowing through the rotor.
[0012]
According to a second aspect of the present invention, there is provided the hermetic motor-equipped compressor according to the first aspect, wherein the magnet cooling means is formed integrally with the rotor and converts the liquid refrigerant into a gas refrigerant. And a flow passage. According to a third aspect of the present invention, in the compressor of the second aspect, the pressure reducing unit is a throttle of a hollow annular member integrated with the rotor.
[0013]
According to a fourth aspect of the present invention, in the first aspect, the flow passage is a magnetic flux leakage preventing gap formed at both widthwise ends of a magnet insertion hole formed in the rotor core of the rotor. According to a fifth aspect of the present invention, in the compressor of the first aspect, the compressor includes a refrigerant suction port in the axial direction near the electric motor and a refrigerant discharge port on a side opposite to the electric motor.
[0014]
According to a sixth aspect of the present invention, the hermetic compressor with a motor further includes a temperature measuring means for measuring the temperature of the rotor and activating the magnet cooling means when the measured temperature exceeds a predetermined value.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
<Closed container>
The closed container having a box shape or a cylindrical shape as a whole may be formed of a single member, or may be formed of a plurality of members. The components of the compressor can be shared as the components of the closed vessel. Since the refrigerant flows through the internal space, it is sealed from the outside world.
[0016]
The hermetic container has a refrigerant inlet at an intermediate portion in the axial direction and a refrigerant outlet at a compressor-side end in the axial direction. The reason why the refrigerant inlet is formed in the axially intermediate portion of the closed container depends on the relationship with the configuration of the coils of the stator. This is because, when the stator includes the pine needle-shaped conductor coil, the joint portion of the conductor coil, which does not easily become a resistance to the flow of the refrigerant, is located radially inward of the intermediate portion.
<Compressor>
The compressor is mounted at one end on the rotating shaft and includes a fixed scroll and a movable scroll. The movable scroll rotates with respect to the fixed scroll by the rotational force of the electric motor, and compresses the refrigerant.
<Electric motor>
{Circle around (1)} The electric motor is arranged at the other end of the rotating shaft alongside the compressor, and includes a stator and a rotor. The rotating shaft has a liquid refrigerant inlet passage at one end in the axial direction opposite to the compressor. The inlet passage has a portion connected to an external refrigerant supply pipe (capillary tube) and a portion communicating with the rotor.
(2) The stator core of the stator (stator) has a cylindrical shape and is fixed to an airtight container. A plurality of conductor coils are inserted into the plurality of through holes.
(3) The rotor (rotor) is a rotor core, a plurality of permanent magnets inserted into each of the plurality of magnet insertion holes of the rotor core, and a decompression unit that converts liquid refrigerant supplied on the anti-compressor side of the rotor core into gas refrigerant. And an annular member having The annular member has a portion that communicates with the rotating shaft and a portion that gasifies the liquid refrigerant and supplies it to the rotor.
[0017]
The rotor core is formed with a refrigerant flow passage penetrating in the axial direction from one end surface to the other end surface. The refrigerant flow passage may be formed near the permanent magnet in the rotor core. For example, in the case of a so-called SPM, a dedicated refrigerant flow passage may be formed outside the magnet insertion hole in the radial direction separately from the magnet insertion hole.
[0018]
On the other hand, in a so-called IPM in which a permanent magnet is built in a magnet insertion hole of a hollow cylindrical rotor core, magnetic flux leakage prevention gaps (flux barriers) exist at both ends in the width direction of the magnet insertion hole. If this gap is used as a coolant flow passage, it is not necessary to provide a dedicated coolant flow passage, which is extremely effective in terms of structure, reduction in the number of parts, and cooling efficiency.
(4) It is desirable that the electric motor includes a temperature measuring means (thermistor) for measuring the temperature of the rotor. When the measured temperature exceeds a predetermined value, the on-off valve is opened and the liquid refrigerant is supplied from the capillary tube.
[0019]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, 3, and 4. FIG.
<Example>
(Constitution)
FIG. 1 shows a refrigeration cycle of the air conditioner system. The gas refrigerant is compressed at a high temperature and a high pressure in a hermetic compressor with electric motor (hereinafter, abbreviated as “hermetic compressor” in the embodiments) A, and is cooled in a condenser B by surrounding cooling water to become a liquid refrigerant. The liquid refrigerant is decompressed and gasified at a low temperature and a constant pressure by the expansion valve C, enters the evaporative gas D, absorbs heat from the air, and is sucked into the hermetic compressor A again. A capillary tube G extends from a liquid receiver E disposed between the condenser B and the expansion valve C to the hermetic compressor A, and an opening / closing valve F is disposed in the middle thereof.
[0020]
As shown in FIG. 2, the hermetic compressor A includes a hermetic container 10, a compressor (compressor) 40, and an electric motor (motor) 53. The closed container 10 includes the main body case 11, the support member 20, and the lid case 46. The main body case 11 has a bottomed cylindrical shape and includes a cylindrical portion 12 and a lid portion 15. A refrigerant inlet 13 extending in the radial direction is formed above the left end of the cylindrical portion 12, that is, at the boundary between the compressor 40 and the electric motor 53.
[0021]
The left end opening of the main body case 11 is covered with a support member 20 having a large-diameter portion 22, a middle-diameter portion 24, and a small-diameter portion 28 having different inner and outer diameters and shifted in the axial direction. The large-diameter portion 22 abuts on the end face of the main body case 11, and the middle-diameter portion 24 rotatably supports the middle large-diameter portion 31 of the rotary shaft 30 via the bearing 25. The small diameter portion 32 at the right end of the rotating shaft 30 is rotatably supported by the lid 15 of the main body case 11 via a bearing 35.
[0022]
The small diameter portion 28 is loosely fitted to the rotating shaft 30. A counter balancer 37 is attached at a position radially inside the large diameter portion 22 of the support member 20 and on the side of the large diameter portion 31 of the rotating shaft 30.
[0023]
The compressor 40 includes a movable scroll 43, a fixed scroll 44, and the like. A movable scroll 41 is attached to the small diameter portion 33 at the left end of the rotating shaft 30 via a slide bush 38, and rotates together with the rotating shaft 30. A fixed scroll 43 provided with a discharge valve 44 at the center thereof is mounted on the outer side (left side) of the movable scroll 41 and the support member 20 in the axial direction so as to cover the movable scroll 41 to form a compression chamber 42. A lid case 46 having a refrigerant discharge port 49 is attached further axially outside the fixed scroll 43 to form a discharge chamber 47.
[0024]
A supply passage 50 for the liquid refrigerant is formed at the right end of the rotating shaft 30. The supply passage 50 includes an axial hole 51 formed at the center of the right end face and formed of a blind hole, and a radial hole 52 extending in the radial direction from the tip thereof and opening on the outer peripheral surface. The capillary tube G is connected to the opening of the axial hole 52.
[0025]
The electric motor 53 is a permanent magnet type brushless inverter motor, in particular, an IPM in which a permanent magnet is incorporated in a rotor core, and includes a stator 55 and a rotor 70. As shown in FIGS. 2 and 3, the stator core 56 of the stator 55 has a cylindrical shape as a whole, and a plurality of through holes 57 penetrating in the axial direction is spaced in the circumferential direction. The conductor coil 60 inserted in the through hole 57 having a circular cross section is formed by joining a plurality of pine needle-shaped conductor segments 62. It includes a pair of axially intermediate housing portions 64 housed in the stator core 56, a pair of joining portions 65 protruding from one end surface, and a U-shaped turn portion 63 protruding from the other end surface.
[0026]
In addition, the thermistor 67 is fixed to the cylindrical portion 12 of the closed container 10, and the temperature of the electric motor 53 is measured. When the measured temperature exceeds a predetermined value, the on-off valve F is opened and the liquid refrigerant in the receiver E is supplied to the hermetic compressor A through the capillary tube G.
[0027]
3 and 4, the rotor 70 includes a rotor core 71, a permanent magnet 75, and end rings 82 and 85 at both ends. The rotor core 71 has a hollow cylindrical shape as a whole, and is prevented from rotating with respect to the rotating shaft 30 by a key 74. Four magnet insertion holes 72 are formed in a portion near the outer peripheral surface. Each magnet insertion hole 72 has a thin and wide cross-sectional shape with a small thickness and a large width, and is formed so as to form a chord with respect to a circle on the outer peripheral surface of the rotor core 71. , Is formed. As a result, the adjacent magnet insertion holes 72 are orthogonal to each other, and the four magnet insertion holes 72 are arranged at positions corresponding to each side of the square.
[0028]
In each magnet insertion hole 72, a thin permanent magnet 75 is disposed so that its inner and outer surfaces in the radial direction have the same polarity. In order to leave the flux barriers 73 at both ends in the width direction of the magnet insertion hole 72, the width of the permanent magnet 75 is selected to be slightly smaller than the width of the magnet insertion hole 72.
[0029]
The left end ring 82 is formed of a solid annular member, and is attached to the rotation shaft 30 so as not to rotate relatively. A curved refrigerant outlet passage 83 is formed from one end face (right end face) to the other end face (left end face).
[0030]
The right end ring 85 is formed of a hollow annular member, and is attached to the rotating shaft 30 so as not to rotate relatively. An appropriate number of refrigerant inlets 86 formed on the inner peripheral surface communicate with the radial holes 54 of the rotating shaft 30. Further, on one end surface (left end surface), a plurality of apertures 88 having a very small cross-sectional area are formed at positions where the magnet insertion holes 72 communicate with the flux barrier 73.
(Actuation)
Next, the operation of the hermetic compressor of the present embodiment will be described. In the electric motor 53, a current flows through the conductor coil 60 of the stator 55, and the rotor 70 is rotated by the electromagnetic force.
[0031]
In the compressor 40, the movable scroll 41 attached to the rotating shaft 30 rotates with respect to the fixed scroll 43, and the refrigerant is sucked inward in the radial direction from the refrigerant inlet 13. After passing through a communication hole (not shown) formed in the support member 20 and the movable scroll 41, it flows into the compression chamber 42 between the movable scroll 41 and the fixed scroll 43. The refrigerant is compressed in the compression chamber 42 by the rotation of the orbiting scroll 41, flows out of the discharge valve 44 to the discharge chamber 47 when the pressure becomes equal to or higher than a predetermined pressure, and is discharged from the refrigerant outlet 49.
[0032]
When the cooling load is relatively small, the suction amount of the refrigerant in the compressor 40 is small, and the rotation speed of the electric motor 53 is relatively small. Therefore, the temperature rise of the rotor 70 measured by the thermistor 67 is low. The on-off valve F remains closed, and no liquid refrigerant is supplied to the capillary tube G.
[0033]
On the other hand, when the cooling load is relatively large, the suction amount of the refrigerant in the compressor 40 is large, and the rotation speed of the electric motor 53 is increased. As a result, the calorific value increases, so that the temperature of the electric motor 53 measured by the thermistor 67 increases. When the measured temperature exceeds a predetermined value, the on-off valve F is opened and the liquid refrigerant is supplied from the receiver E to the capillary tube G. The liquid refrigerant is supplied from the capillary tube G to the electric motor 53 in parallel with the suction of the refrigerant from the refrigerant inlet 13 into the compressor 40.
[0034]
More specifically, the liquid refrigerant supplied from the capillary tube flows from the axial hole 51 of the rotating shaft 30 to the radial hole 52, and flows into the side ring 85 from the refrigerant inlet 86. When flowing through the throttle 88, the pressure is reduced and gasified, and the gas refrigerant flows from one end surface of the rotor 70 to the other end surface in the flux barrier 73 formed on both sides in the width direction of the magnet insertion hole 72. At that time, the liquid refrigerant evaporates by absorbing the high heat of the permanent magnet. Thus, the permanent magnet 75 is cooled from both sides in the width direction by the heat of vaporization, and its temperature rise is suppressed.
[0035]
The refrigerant that has reached the other end surface flows out of the refrigerant outlet passage 83 of the left end ring 82, merges with the refrigerant sucked from the refrigerant suction port 13, and is compressed.
(effect)
According to the hermetic compressor A of the present embodiment, the following effects can be obtained.
[0036]
First, the cost of the permanent magnet 75 and thus the rotor 70 is reduced. As can be seen from FIG. 4, since the gas refrigerant flowing through the flux barrier 73 controls the temperature rise of the permanent magnet 75, the heat resistance of the neodymium permanent magnet 75, which is relatively expensive among the permanent magnets, is low. This is because it is possible to use a low-priced grade.
[0037]
On the other hand, since the cooling of the permanent magnet is insufficient as in the prior art, an expensive neodymium magnet is adopted in consideration of heat resistance, which causes an increase in cost.
[0038]
Second, the axial dimension of the hermetic compressor A is reduced. As can be seen from FIG. 2, the refrigerant suction port 13 is located on the stator 55 on the joint portion 63 side of the conductor coil 60. There is a certain gap between the joints 63 of each conductor coil 60 (not so dense). Therefore, the refrigerant drawn inward in the radial direction from the refrigerant suction port 13 can pass through the gap between the joining portions 63 adjacent in the circumferential direction, and there is no need to provide an extra gap for the passage of the refrigerant. .
[0039]
On the other hand, when the coolant suction port is provided on the turn portion side of the conductor coil as in the related art, it is difficult for the coolant to pass between the dense turn portions. Therefore, it is necessary to provide a gap between the turn part and the closed container (particularly, the lid part), and the axial length of the motor has been increased accordingly.
[0040]
Third, the electric motor 70 is made of an IPM including a permanent magnet 75, can obtain high characteristics, and is convenient for cooling the permanent magnet 75. This is because the gap between the stator 55 and the rotor 70 is made as small as possible, and the flux barriers 73 are formed at both ends in the width direction of the magnet insertion hole 72.
[0041]
On the other hand, the reason why the cooling of the permanent magnets 75 is convenient is that the flux barriers 73 at both ends in the width direction of the magnet insertion holes 72 which originally exist can be used as the coolant flow passages, and a new passage is not required. Moreover, even if the gas refrigerant flows through the flux barrier 73, the performance of the rotor 70 is not affected at all.
[0042]
Finally, the operation of forming the refrigerant inlet passage 50 in the rotating shaft 30 is not difficult, and the pair of end rings 82 and 85 disposed at both ends of the rotor core 71 are also simple members. The above advantage that the permanent magnet 75 can be used at low cost in place of the conventional expensive permanent magnet exceeds the cost required for these operations and arrangements.
<Modification>
FIG. 5 shows a modification of the rotor. In the rotor 90, each of the four magnet insertion holes 92 formed in the rotor core 91 is defined by a planar inner surface 93, a curved outer surface 94, and a pair of connection surfaces 95. The inner surface 93 extends in parallel with the diameter and forms a chord with the circle of the outer peripheral surface 97 of the rotor core 91. The outer surface 94 extends along the outer peripheral surface 97 so that an arc-shaped bridge 98 having a constant thickness is formed. A pair of connecting surfaces 95 formed at both ends of the inner surface 93 and the outer surface 94 extend substantially in the radial direction of the rotor core 91.
[0043]
The permanent magnet 100 inserted into the magnet insertion hole 92 has an inner surface 101 having the same shape as the inner surface 93 of the rotor core 90, an outer surface 102 having a slightly larger curvature than the outer surface 94, and connecting surfaces 103 at both ends. Due to the difference in curvature between the inner surface 94 and the inner surface 102, a flux barrier 105 extending in the circumferential direction is formed between the two. The size of the flux barrier 105 in the radial direction is large on the connection surface 103 side, and decreases as the distance from the connection surface 103 increases.
[0044]
When the cooling load is large during the operation of the hermetic compressor A, the gas refrigerant depressurized by the throttle 88 of the side ring 85 is allowed to flow through the flux barrier 105.
[0045]
According to this modification, more excellent characteristics can be obtained because the refrigerant contact area of the permanent magnet 100 is large. Further, although the thickness of the permanent magnet 100 is relatively large, a wide range of the outer surface 102 is cooled by the gas refrigerant flowing in the flux barrier 105, and the temperature rise is effectively suppressed.
[0046]
【The invention's effect】
As described above, according to the hermetic motor-equipped compressor of the present invention, when the cooling load is large, the magnet cooling means circulates the gas refrigerant in the rotor to cool the permanent magnet and raise the temperature thereof. Suppress. As a result, it is not necessary to attach importance to the heat resistance of the permanent magnet, an inexpensive permanent magnet can be used, and the cost of the rotor and thus the motor can be reduced. In addition, the refrigerant suction port of the compressor can be formed in a place convenient for the compressor without considering the cooling of the rotor, and at a place where the suction resistance is small in relation to the stator of the electric motor.
[0047]
According to the hermetic compressor with the electric motor of the second aspect, the liquid refrigerant supplied from the outside is reliably gasified and can be used for cooling the permanent magnet of the rotor. According to the compressor of the third aspect, the liquid refrigerant can be changed to the gas refrigerant immediately before the liquid refrigerant is introduced into the rotor. According to the compressor with the hermetic motor of the fourth aspect, it is not necessary to newly form a flow passage for the refrigerant in the rotor, and an increase in cost can be suppressed as much as possible.
[0048]
According to the compressor of the fifth aspect, the coils of the stator of the electric motor are not so dense on the compressor side, and the suction resistance of the refrigerant is small. Therefore, it is not necessary to secure a space for refrigerant circulation around the coil, and the axial length can be shortened by that amount. According to the compressor with the hermetic motor of the sixth aspect, when the cooling load is large and the temperature of the motor easily rises, the refrigerant is reliably supplied from the magnet cooling means.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a refrigeration cycle of an air conditioner.
FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention.
FIG. 3 is a transverse sectional view of the same; FIG. 4 is an enlarged view of a main part of FIG. 2;
FIG. 5 is a cross-sectional view of a main part showing a modification of the embodiment.
[Explanation of symbols]
A: Hermetic compressor with motor 10: Hermetic container 40: Compressor 50: Refrigerant inlet passage 53: Motor 55: Stator 56: Stator core 60: Conductor coil 70: Rotor 71: Rotor core 72: Magnet insertion hole 73: Flux barrier 75 : Permanent magnet 82: Side ring 88: Aperture

Claims (6)

In a compressor with a hermetic motor in which a compressor and a motor for driving the compressor are arranged side by side on a rotating shaft supported by a closed container, the motor is:
A stator fixed to the closed container,
A rotor having a permanent magnet and rotatably supported by the closed container,
Magnet cooling means for gasifying a liquid refrigerant supplied from the opposite side of the compressor in the axial direction, flowing the inside of the rotor toward the compressor, and cooling the permanent magnet,
A hermetic motor-equipped compressor comprising: 2. The hermetic electric motor according to claim 1, wherein the magnet cooling unit includes a decompression unit formed integrally with the rotor and converting a liquid refrigerant into a gas refrigerant, and a gas refrigerant flow passage formed on the rotor. 3. With compressor. The hermetic compressor with a motor according to claim 2, wherein the pressure reducing unit is a throttle of a hollow annular member integrated with the rotor. 3. The hermetic motor-equipped compressor according to claim 2, wherein the flow passage is a magnetic flux leakage preventing gap formed at both ends in a width direction of a magnet insertion hole formed in a rotor core of the rotor. 2. The compressor according to claim 1, wherein the compressor has a refrigerant suction port in the axial direction near the electric motor, and has a refrigerant discharge port on a side opposite to the electric motor. 3. 2. The hermetic motor-equipped compressor according to claim 1, further comprising a temperature measuring means for measuring a temperature of said electric motor and activating said magnet cooling means when the measured temperature exceeds a predetermined value.

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