JP4000770B2 - Electric compressor and cooling method of electric compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric compressor including an electric motor as a drive source, and more particularly to a cooling technique for the electric motor.
[0002]
[Prior art]
Conventionally, a technique for cooling an electric motor which is a drive source of an electric compressor is described in, for example, Japanese Patent Laid-Open No. 4-80554. The electric compressor described in the above publication employs a system in which the electric motor is cooled by suction refrigerant, and all the suction refrigerant returning from the external circuit is introduced into the compression chamber via the motor chamber.
[0003]
[Problems to be solved by the invention]
However, according to the cooling method described in the above publication, the refrigerant sucked through the motor chamber is heated by cooling the electric motor. Therefore, when the heat generation amount of the electric motor is large, there is a problem that the specific volume of the suction refrigerant increases and the compression efficiency decreases.
[0004]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to avoid an adverse effect on compression work and to cool an electric motor with a refrigerant. And it is providing the cooling method of an electric compressor.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a compressor according to the present invention has a configuration as described in each claim. According to the first aspect of the present invention, in the electric compressor using the electric motor as a drive source, the motor chamber in which the electric motor is accommodated is a sealed space, and the refrigerant flow path from the motor chamber to the suction to the discharge Are communicated with each other only by a communication path communicating with the inlet of the suction refrigerant in the compression mechanism . The motor chamber is not used as a passage for sucked refrigerant. Therefore, during the operation of the compressor, heat is transferred between the refrigerant on the distribution path side and the refrigerant on the motor chamber side. That is, the heat on the motor chamber side, which is the high heat side, moves to the flow path side, and the electric motor is cooled by this heat movement. In addition, when a pressure difference occurs between the flow path side and the motor chamber side, the refrigerant flows through the communication path so that the pressure is equal between the two. The electric motor is cooled by the accompanying heat transfer. Thus, the invention according to claim 1 does not use the motor chamber as a refrigerant passage, but cools the electric motor in a so-called “stagnation” state of the refrigerant in the motor chamber. Therefore, the refrigerant related to the cooling of the electric motor is a part of the refrigerant flowing from the suction to the discharge, and therefore has little influence on the compression work of the compressor.
[0006]
In this case, as described in claim 2, it is preferable that the refrigerant flow path is provided on the compression mechanism side . According to another aspect of the present invention, in order to communicate with the inlet of the suction refrigerant in the compression mechanism , the communication path connects the motor chamber with the suction region in the suction path where the suction refrigerant flows . When the configuration in which the suction area and the motor chamber are communicated with each other, the cooling effect can be enhanced because the cooling is performed by the suction refrigerant having a temperature lower than that of the discharged refrigerant, and the cooling effect can be increased as compared with the above-described conventional technology. The increase in volume is suppressed and the compression efficiency does not decrease.
In addition, as described in claim 3 , it is preferable that the refrigerant flowing into the distribution path flows in the inverter that controls the electric motor. According to such a configuration, in addition to being able to cool the electric motor with the refrigerant, it is also possible to cool the inverter that is a control part of the electric motor.
[0007]
According to the cooling method of the electric compressor according to claim 4 , the refrigerant capable of cooling the electric motor while avoiding the adverse effect on the compression work when the cooling method of the electric motor by the refrigerant is adopted. The cooling method can be provided. In this case, as described in claim 5 , the refrigerant used for cooling the motor chamber is preferably an intake refrigerant.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a scroll type electric compressor and a cooling method for the compressor according to an embodiment of the present invention will be described with reference to FIGS. 1 is a longitudinal sectional view showing the entire scroll compressor, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is a drawing showing the arrangement of switching elements.
As illustrated, one end surface of the center housing 4 is joined to one end surface of the fixed scroll 2, and the motor housing 6 is joined to the other end surface of the center housing 4. The fixed scroll 2 and the two housings 4 and 6 constitute a compressor body 7. A drive shaft 8 is rotatably supported by the center housing 4 and the motor housing 6 via radial bearings 10 and 12, and the drive shaft 8 is located on the side of the center housing 4 with respect to the drive shaft 8. An eccentric shaft 14 is integrally formed at an eccentric position.
[0009]
A bush 16 is fitted to the eccentric shaft 14 so as to rotate integrally. A balance weight 18 is provided at one end portion of the bush 16 so as to rotate integrally, and the other end portion of the bush 16 is relatively rotated via a needle bearing 22 so that the movable scroll 20 faces the fixed scroll 2. It can be fitted. The needle bearing 22 is accommodated in a cylindrical boss portion 24 a that protrudes from the back surface of the movable scroll substrate 24 in the movable scroll 20.
[0010]
The fixed scroll substrate 26 and the fixed spiral wall 28 of the fixed scroll 2 and the movable scroll substrate 24 and the movable spiral wall 30 of the movable scroll 20 are crescent shaped by contacting the fixed spiral wall 28 and the movable spiral wall 30 at a plurality of points. A compression chamber (sealed space) 32 is formed. The fixed scroll 2 and the movable scroll 20 constitute a compression mechanism 21. The movable scroll 20 revolves (orbits) as the eccentric shaft 14 rotates (orbits), and the balance weight 18 cancels the centrifugal force associated with the revolution of the movable scroll 20 at that time. The rotational force of the drive shaft 8 is applied to the movable scroll 20 by the eccentric shaft 14 that rotates integrally with the drive shaft 8, the bush 16, and the needle bearing 22 that is interposed between the eccentric shaft 14 and the boss portion 24 a of the movable scroll 20. A revolution mechanism that conveys it as a revolution movement is configured.
[0011]
On the end surface of the center housing 4, a plurality of (for example, four) rotation-preventing recesses 34 are formed at equal angular positions on the same circumferential line. The fixed pin 36 fixed to the center housing 4 and the movable pin 38 fixed to the movable scroll substrate 24 are fastened in a state of being inserted into the recess 34. The movable scroll 20 is prevented from rotating by the recess 34, the fixed pin 36, and the movable pin 38 as the eccentric shaft 14 rotates. That is, the recess 34, the fixed pin 36, and the movable pin 38 constitute a mechanism for preventing the rotation of the movable scroll 20, and the movable scroll 20 is revolved when the eccentric shaft 14 rotates.
A stator 44 is fixed to the inner peripheral surface of the motor housing 6, and a rotor 45 is fixed to the drive shaft 8. An electric motor 46 is constituted by the stator 44 and the rotor 45, and the rotor 45 and the drive shaft 8 rotate together by energizing the stator 44. That is, the electric motor 46 is accommodated in a sealed motor chamber 48 formed by the motor housing 6 and the center housing 4.
[0012]
As the eccentric shaft 14 of the drive shaft 8 rotates, the movable scroll 20 revolves, and the suction refrigerant introduced from the inlet 42 flows between the fixed scroll substrate 26 and the movable scroll substrate 24 from the peripheral sides of the scrolls 2, 20. Flows in between. At this time, with the rotation of the eccentric shaft 14, the movable scroll 20 tries to rotate around the central axis of the bush 16, but the rotation is prevented by the above-described rotation prevention mechanism.
That is, when the eccentric shaft 14 rotates, the movable scroll 20 attached to the eccentric shaft 14 through the needle bearing 22 so as to be relatively rotatable revolves around the central axis of the drive shaft 8 without rotating.
As the movable scroll 20 revolves, the suction refrigerant introduced from the inlet 42 flows into the compression chamber 32, and the compression chamber 32 moves from the outer peripheral side to the inner peripheral side while reducing the volume. The spiral walls 28 and 30 converge toward the inner peripheral end. The intake refrigerant inlet 42 is formed in the fixed scroll 2.
[0013]
A discharge port 50 is formed at the center of the fixed scroll substrate 26, and the discharge port 50 communicates with the final compression chamber 32. A discharge chamber 52 is formed on the back side of the fixed scroll substrate 26, and a discharge valve 54 that opens and closes the discharge port 50 is provided in the discharge chamber 52. The discharge valve 54 includes a reed valve 56 and a retainer 58. The discharge chamber 52 is covered by a rear cover 51, and a refrigerant discharge pipe (not shown) of an external circuit is connected to the outlet 51a of the rear cover 51.
[0014]
In the center housing 4 that partitions the compression mechanism 21 side and the motor chamber 48, a communication path for communicating with the motor chamber 48 the suction region in the refrigerant flow path from suction to discharge formed on the compression mechanism 21 side. 49 is provided. That is, the inlet 42 of the suction refrigerant communicates with a space 49a formed between the outer peripheral surface of the movable scroll substrate 24 and the inner wall surface of the scroll accommodating space that accommodates the movable scroll substrate 24. The motor chamber 48 communicates with a communication hole 49 b provided in the center housing 4. The space 49a and the communication hole 49b constitute a communication path 49. The communication path 49 is a refrigerant flow path regardless of the position of the movable scroll substrate 24 that revolves in the scroll accommodating space during the operation of the compressor. On the other hand, the communication state is always maintained.
[0015]
A flat mounting surface 7a is formed on the outer upper surface in the radial direction of the body 7, and an inverter 60 constituting a control unit for controlling the electric motor is mounted on the mounting surface 7a. Components constituting the inverter 60 are divided into high heat generating components such as a plurality of switching elements 62 having high heat generation and low heat generating components such as a plurality of capacitors 64 having relatively low heat generation and are accommodated in the unit housing 70. Has been.
[0016]
The switching element 62 is disposed in the cylindrical portion 70a of the unit housing 70, and is supported so as to stick to the outer peripheral surface of the cylindrical body 63 disposed in the cylindrical portion 70a. That is, as shown in FIG. 3, a plurality of flat mounting surfaces 63 a for mounting the switching elements 62 are formed on the outer peripheral surface of the cylindrical body 63. In the present embodiment, it is formed in a substantially triangular shape having three attachment surfaces 63a, and the switching elements 62 divided into three blocks are supported directly in contact with each attachment surface 63a (attached state). The On the other hand, the capacitor 64 and the like are supported by the mounting plate 65.
[0017]
One end of the cylindrical body 63 passing through the unit housing 70 is connected to the inlet 42 of the compression chamber 32, and the other end is connected to a refrigerant suction pipe (not shown) of the external circuit. On the other hand, the unit housing 70 that accommodates the inverter 60 is formed of a heat insulating material, preferably a synthetic resin, and its bottom plate 70b is separated from the mounting surface 7a of the airframe 7 by a predetermined gap C via the legs 70c. It is attached in the state. A heat insulating region is formed by the gap C.
[0018]
Further, the switching element 62 in the unit housing 70 and the electric motor 46 in the motor housing 6 are connected to each other by three conductive pins 66 and lead wires 67 and 68 that penetrate into the motor housing 6 and the unit housing 70. The electric power required for driving the electric motor 46 is supplied through the conductive pins 66 and the conductive wires 67 and 68.
[0019]
In the scroll-type electric compressor configured as described above, when the compression mechanism 21 is driven by the electric motor 46, the refrigerant sucked from the inlet 42 is compressed and discharged from the discharge port 50 as a high-pressure refrigerant into the discharge chamber 52. Then, as shown by the arrow in FIG. 1, it is sent to a capacitor (not shown) of the external circuit. On the other hand, the suction refrigerant returning from the evaporator (not shown) of the external circuit returns to the compressor through the cylindrical hole 63b of the cylindrical body 63 penetrating the unit housing 70 as shown by the arrow in FIG. Heat is taken from the inverter 60 in the housing 70, in particular, the switching element 62, which is a high heat generating component supported by the cylinder 63, and is cooled.
[0020]
Further, during the operation of the compressor, the body 7 is heated by heat generated by compression of the refrigerant or heat generated by driving the electric motor 46. However, in the present embodiment, the unit housing 70 in which the inverter 60 is accommodated is arranged with a predetermined gap C from the airframe 7 as the heat generating component, in particular, the motor housing 6, so that heat insulation composed of an air layer is achieved. Since the region is set, it is thermally insulated by this heat insulating region, and the heat generated in the electric motor 46 is prevented from moving to the unit housing 70. The effect of suppressing heat transfer by the heat insulation region is continuously exhibited even when the compressor is stopped.
[0021]
During the operation of the compressor, the motor chamber 48 is always in communication with the suction area in the refrigerant flow path via the communication path 49. Therefore, heat transfer occurs between the suction refrigerant on the distribution path side and the refrigerant on the motor chamber 48 side via the communication path 49. That is, the heat on the motor chamber 48 side, which is the high heat side, moves to the flow path side, and the electric motor 46 is cooled by this heat movement. In addition, when a pressure difference is generated between the motor chamber 48 and the refrigerant suction area, a refrigerant flow is generated between the motor chamber 48 and the suction area via the communication path 49. Therefore, heat is transferred with the refrigerant flow, and the electric motor 46 is cooled. Thus, overheating of the electric motor 46 is prevented.
[0022]
The cooling described above is so-called “stagnation cooling” that does not involve a large flow of the suction refrigerant, unlike a conventional system in which the motor chamber is used as a passage for the suction refrigerant. The suction refrigerant that is directly related to such “stagnation cooling” is a part of the suction refrigerant that circulates in the flow path, and does not significantly increase the temperature of the entire suction refrigerant. For this reason, an increase in the specific volume of the suction refrigerant is suppressed, and the problem that the compression efficiency is reduced can be solved.
In the present embodiment, a configuration in which the inverter 60 is cooled by the suction refrigerant is employed. However, the heat generation amount of the inverter 60 is extremely small as compared with the heat generation amount of the electric motor 46. Therefore, compared to the case where all the intake refrigerant is circulated in the motor chamber 48 and the electric motor 46 is cooled, the temperature rise of the intake refrigerant when the inverter 60 is cooled with the intake refrigerant is small, and the compression efficiency is reduced. It does not lead to a decrease.
[0023]
In the present embodiment, since a low-temperature suction refrigerant is used for cooling the electric motor 46, a higher cooling effect can be obtained as compared with the discharge refrigerant. Furthermore, according to the configuration in which the sucked refrigerant is guided to the motor chamber 48, there is no need to provide a seal material around the drive shaft 8 that transmits the driving force of the electric motor 46 to the compression mechanism 21, and the structure is simple and advantageous in terms of cost. Become.
[0024]
In addition, this invention is not limited to embodiment of illustration, It can change suitably in the range which does not deviate from the summary.
For example, in the embodiment, the inverter 60 is integrated with the compressor and the inverter 60 is cooled by the suction refrigerant. However, the inverter 60 may be applied to a type in which the inverter 60 is provided independently from the compressor.
In addition, the communication part of the motor chamber 48 with respect to the flow path through the communication path 49 is not limited to the suction area, and may be anywhere as long as it is a flow path of refrigerant from suction to discharge. For example, the discharge chamber 52 and the motor chamber 48 may be communicated with each other through a communication path, and the electric motor 46 may be cooled by the discharged refrigerant.
[0025]
【The invention's effect】
As described above in detail, according to the present invention, the electric compressor and the electric compression capable of cooling the electric motor while avoiding the adverse effect on the compression work when the cooling method of the electric motor by the refrigerant is adopted. A method of cooling the machine can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an entire scroll compressor.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a diagram showing an arrangement of switching elements.
[Explanation of symbols]
2 fixed scroll 4 center housing 6 motor housing 20 movable scroll 21 compression mechanism 32 compression chamber 42 inlet 46 electric motor 48 motor chamber 49 communication path

Claims (5)

An electric compressor comprising: a compression mechanism that compresses suction refrigerant and discharges it as high-pressure discharge refrigerant; and an electric motor that drives the compression mechanism,
The refrigerant flow path from suction to discharge communicates with the sealed motor chamber that houses the electric motor only by a communication path that communicates with the inlet of the suction refrigerant in the compression mechanism , and the motor chamber is inhaled. An electric compressor characterized by not being configured as a refrigerant passage .   The electric compressor according to claim 1, wherein the distribution path is provided on the compression mechanism side. 3. The electric compressor according to claim 1, wherein the refrigerant flowing into the distribution path flows in an inverter that controls the electric motor. 4. An electric compressor cooling method comprising: a compression mechanism that compresses suction refrigerant and discharges it as high-pressure discharge refrigerant; and an electric motor that drives the compression mechanism,
The refrigerant flow path from suction to discharge communicates with the sealed motor chamber that houses the electric motor only by a communication path that communicates with the inlet of the suction refrigerant in the compression mechanism , and the motor chamber is inhaled. An electric compressor that cools the electric motor by moving heat between the refrigerant on the distribution path side and the refrigerant on the motor chamber side via the communication path instead of a refrigerant path. Cooling method. 5. The method for cooling an electric compressor according to claim 4 , wherein the electric motor is cooled by heat transfer between the suction refrigerant flowing through the distribution path and the refrigerant on the motor chamber side. The cooling method of the electric compressor.

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