JP3916062B2 - Electric compressor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electric compressor for compressing a refrigerant to which a protection device used for refrigerant compression such as an air conditioner or a refrigerator is attached, and proposes a structure for the protection device to detect the refrigerant temperature more efficiently. It is.
[0002]
[Prior art]
Conventionally, in electric compressors used in refrigeration cycles such as air conditioners and refrigerators, an overcurrent due to overload or heat generation due to internal abnormality was detected, and a protective device was installed to protect the motor from dangers such as burning. Things are used. There are two types of protective devices, one that is attached to the outside of the pressure vessel of the electric compressor and one that is built in the pressure vessel. It is advantageous.
[0003]
In an electric compressor incorporating such a protection device, conventionally, the protection device is attached to the coil end of the motor with a string or the like. Since this protective device is exposed to the compressed refrigerant in the pressure vessel of the electric compressor, it has a metal hermetic container structure, and has a contact mechanism using a thermally responsive plate such as a bimetal inside the hermetic vessel. This contact mechanism is designed to receive heat from the surroundings and to allow the internal components to self-heat by passing an energizing current to the motor. When current increases due to ambient overheating or overload, The temperature of the response plate rises to reach the operating temperature, and the contacts are opened.
[0004]
When the protective device is mounted on the coil end in this way, the heat generated by the protective device increases due to an increase in current in an overload state or the like, and at the same time, the heat transmitted to the protective device increases as the coil temperature also increases. Therefore, it is possible to detect abnormalities quickly. However, the work of tying and fixing on the coil end has problems such as difficulty in mechanization and complicated manufacturing work. In addition, since the heat from the coil end is always received, the normal temperature of the protective device itself also increases, so the operating temperature of the thermal response plate must be set relatively high, and the temperature difference between normal operation and abnormal conditions is increased. It becomes difficult to take. In this way, if the temperature difference between normal operation and abnormal condition cannot be taken sufficiently, it reacts sensitively to temporary current increase due to short-time overload that should be allowed, so the normal current is particularly large. Those having a large amount of heat generated by the coil or coil have been difficult to use as a protective device.
[0005]
On the other hand, as an example of the electric compressor in which the protection device is attached in another configuration, a device in which the protection device is attached to the inner surface of the pressure vessel or the conductive terminal by a mounting bracket or a terminal has been proposed. In this way, when the protective device is attached to the inner surface of the pressure vessel, the attaching operation can be simplified as compared with the case where the protective device is tied with a string or the like. Moreover, since it becomes a structure cooled with a refrigerant | coolant, it can be used with a comparatively big electric current also with the same protective device compared with the case where it mounts on a coil.
[0006]
Further, in this case, the mounting posture of the protection device is determined by the mounting terminal and the like, thereby determining the position where the charging part such as the metal airtight container of the protection device is close to the metal part of the compressor. Therefore, it is not necessary to cover the entire container with an insulator, and the area where the airtight container directly contacts the refrigerant can be increased by covering only the necessary part. The temperature of the discharge refrigerant flowing in the pressure vessel is lower than the coil of the electric motor, and flows toward the discharge pipe while cooling the coil. That is, since the refrigerant is heated by the coil, it is possible to detect overheating of the coil through the refrigerant by disposing a protective device downstream thereof.
[0007]
In addition, by setting the thermal reaction plate so that it does not reach the operating temperature by cooling the protective device by cooling the protective device due to the heat generated by the self-heating of the protective device during normal operation, Since the protective device is not sufficiently cooled not only when the temperature of the refrigerant is increased but also when the refrigerant is reduced due to leakage or the like, the protective device operates and can cut off the power supply to the motor.
[0008]
[Problems to be solved by the invention]
However, in the installation of the conventional protective device, the protective device is in the pressure vessel and exposed to the refrigerant, but the flow of the refrigerant is not necessarily taken into consideration, so in terms of heat exchange with the refrigerant, There were aspects that could not be said to be sufficiently efficient. Accordingly, the present invention proposes an electric compressor having a structure in which the heat exchange relationship between the protective device and the refrigerant is improved.
[0009]
[Means for Solving the Problems]
The electric compressor of the present invention is a so-called high-pressure electric compressor in which refrigerant discharged from the compressor circulates in the pressure vessel. The electric compressor includes a protective device between the electric motor and the discharge pipe, and the protective device is made of metal. It consists of a protector body having an airtight container and a holder for storing it, and the holder of this protective device is a refrigerant passage.
[0010]
According to the present invention, the refrigerant discharged from the compressor and cooling the electric motor directly hits the protector main body by flowing in the holder of the protective device, so that the heat exchange relationship between the refrigerant and the protector main body is improved. Therefore, when the refrigerant is heated due to an abnormality of the compressor or an overcurrent to the electric motor, the protector body can reliably detect the temperature rise.
[0011]
Further, the second invention is characterized in that the holder of the protective device is connected to the discharge pipe of the pressure vessel, and the refrigerant flows into the discharge pipe through the holder. According to the present invention, since the holder of the protection device is substantially a part of the discharge pipe, the circulating refrigerant always passes through the protection device and comes into contact with the protector main body, so that heat can be efficiently exchanged between the protector and the refrigerant. .
[0012]
According to a third aspect of the present invention, a partition having a through hole serving as a refrigerant passage is provided in the pressure vessel, and the protection device is disposed on the partition, and the holder of the protection device is communicated with the through hole. It is characterized in that the refrigerant flows directly into the holder.
[0013]
According to the present invention, since the protective device is arranged on the partition wall, the protective device can be easily attached and the refrigerant can be surely flowed into the holder, so that the heat exchange relationship between the refrigerant and the protector body is improved. Can do.
[0014]
Further, the fourth aspect of the invention is characterized in that a plurality of refrigerant passages are provided in the holder of the protective device so that the refrigerant passing through each refrigerant passage hits a different surface of the protector body, in particular, on the downstream side of the protector flow passage. Therefore, it is possible to prevent the refrigerant from staying and to efficiently contact the entire surface of the protector main body.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the electric compressor of the present invention will be described with reference to the drawings. The electric compressor 1 is for compressing a refrigerant used for an air conditioner, for example, and an electric motor 3 and a compressor 4 are enclosed in a metal pressure vessel 2. The pressure vessel 2 is provided with a refrigerant suction pipe 5 and a discharge pipe 6 penetrating the container, and the suction pipe 5 is directly connected to the compressor 4. This electric compressor is a so-called high pressure type, and the refrigerant sucked through the suction pipe 5 from a heat exchanger or the like (not shown) is compressed by the compressor 4 and discharged into the pressure vessel. Then, the refrigerant passes through the gap of the electric motor 2 and is sent again to the refrigeration cycle including the expansion valve and the heat exchanger through the discharge pipe 6 while taking the heat of the electric motor.
[0016]
The electric motor 3 includes a stator 3A and a rotor 3B fixed to a container, and the rotor 3B is connected to the compressor 4 by a drive shaft 7. The end of the drive shaft 7 opposite to the compressor is supported by a bearing plate 8. The bearing plate 8 has a bearing 8A at its center and is configured to hold the end of the drive shaft 7 rotatably, and is provided with a hole through which a refrigerant and a lead wire for power feeding pass. An oil pump 9 is disposed on the bearing 8A, and the lubricating oil 10 enclosed in the pressure vessel is sent to sliding parts such as a bearing and a compressor.
[0017]
In the present invention, the protection device 11 is disposed on the opening of the pressure vessel of the discharge pipe 6. As shown in FIGS. 2 and 3, the protective device 11 includes a protector body 12 having an opening / closing mechanism using a thermally responsive plate such as a bimetal in a metal airtight container, and a synthetic resin made to hold the protector body 12. It is comprised from the electrically insulating holder. The holder includes a cylindrical external holder 13 and an internal holder 14. The protector 11 is configured by inserting the protector 12 and the internal holder 14 into the cylindrical portion 13 </ b> A from one end of the external holder 13. The other end of the external holder 13 is provided with a through hole 13B through which the terminal of the protector 12 is inserted, and the cylindrical portion 13A is provided with a plurality of openings 13C. Further, the inner holder 14 is provided with a plurality of arm-like portions 14B at one end of the cylindrical portion 14A, holds the protector 12 at the tip of the bay-like portion 14B inside the outer holder 13 and secures a refrigerant passage.
[0018]
The protection device 11 is attached to the inner surface of the pressure vessel 2 of the electric compressor 1. In this embodiment, the protection device 11 is protected by holding a holding portion 13 </ b> D of the external holder 13 with a mounting bracket 15 fixed to the pressure vessel 2. The device 11 is fixed. Further, the protection device 11 is attached to the opening of the discharge pipe 6, so that the refrigerant in the pressure vessel 2 is guided to the discharge pipe 6 after passing through the holder of the protection device 11. In this embodiment, the refrigerant flows through the opening 13 </ b> C of the external holder 13 as shown by a dotted line in FIG. 2, and further passes between the arm-shaped portions 14 </ b> B of the internal holder 14 and flows into the cylindrical portion of the internal holder 13. Here, by setting the position of the opening 13C of the external holder 13 to a position where at least part of the container of the protector 12 is directly exposed, the refrigerant flowing into the holder from the opening 13C surely hits the metal surface of the protector 12. become.
[0019]
The electric motor 3 of this embodiment is a three-phase induction motor, and terminals 12A, 12B and 12C provided on the protector 12 are connected to the coil of the electric motor 3 via connection lines 16, respectively. Further, the coil of the electric motor is connected to the sealed terminal 18 via the lead wire 17 so that it can be connected to a power source outside the pressure vessel.
[0020]
Next, the operation of the electric compressor 1 will be described. When the electric motor 3 in the pressure vessel 2 starts to rotate, the compressor 4 is driven via the drive shaft 7. A refrigerant suction pipe 5 is directly connected to the compressor 4, and the refrigerant compressed by the compressor is discharged into the pressure vessel 2. The discharged refrigerant passes through the gap between the rotor and the stator of the motor and the gap between the inner surface of the pressure vessel and the stator so as to take the heat of the motor 3 and cool the inside of the pressure vessel while cooling, and exchange heat from the discharge pipe 6 (not shown). Sent to containers.
[0021]
In the present embodiment, the protective device 11 covers the opening of the discharge pipe 6 and the holder of the protective device is virtually directly connected to the discharge pipe, so that more refrigerant passes through the protective device. . Further, since the refrigerant introduced into the protection device 11 passes while contacting the protector body 12, the protector body 12 can always be efficiently cooled during normal operation.
[0022]
Specifically, as indicated by a dotted line in FIG. 2, the refrigerant flowing into the holder from the opening 13 </ b> C of the external holder 13 contacts the container surface of the protector 12 and performs heat exchange. Further, the refrigerant passing between the arm portions 14B of the inner holder 14 passes through the inside of the cylindrical portion 14A of the inner holder and is sent from the discharge pipe 6 to an external heat exchanger (not shown). Here, when heat is exchanged between the protector 12 and the refrigerant, the refrigerant takes the heat of the protector during normal operation, so that a higher rated current than the conventional one can flow in this embodiment with good heat exchange efficiency. . In addition, the protector operates at the operating temperature not only when the coil temperature of the electric motor 3 and the internal heat generation of the protector 12 increase due to overcurrent or the like, but also when the refrigerant temperature increases due to an increase in the friction of the compressor or the cooling capacity decreases due to refrigerant leakage. Therefore, energization to the motor can be surely cut off.
[0023]
As described above, in the electric compressor of the present embodiment, after the protective device arranged in the pressure vessel is substantially connected to the end of the discharge pipe, the heat is discharged from the compressor and exchanged heat with the electric motor. This makes it possible to efficiently contact the protector and improve the heat exchange relationship. Therefore, during normal operation, the protection device is always cooled efficiently, and even when the same operating temperature is used, it can be used for an electric compressor having a higher operating current than the conventional one. Further, since the refrigerant reaches the protective device through the compressor and the electric motor, it is possible to detect an abnormality of these devices from the rise in the refrigerant temperature.
[0024]
Conventionally, even if a protective device is placed in the refrigerant flow, the refrigerant flow has not been controlled, so the amount of contact between the refrigerant and the protector body may not be sufficient, and efficient heat exchange may not be possible. However, according to the present invention, the holder of the protective device is used as a refrigerant passage, and the circulating refrigerant is collected and flowed in this holder, so that the refrigerant efficiently contacts the periphery of the protector body to exchange heat. The relationship becomes very good.
[0025]
Next, another embodiment of the electric compressor according to the present invention will be described with reference to FIGS. The same parts as those in the above-described embodiment are denoted by the same symbols, and detailed description thereof is omitted. The electric compressor 21 of the present embodiment also includes an electric motor 3 and a compressor 4 inside a metal pressure vessel 2 as in the above example, and the electric motor and the compressor are connected via a drive shaft 7. Yes. The end of the drive shaft 7 opposite to the compressor is supported by a bearing 8A provided at the center of the bearing plate 8. The bearing plate 8 is formed in a disc shape substantially along the inside of the vessel and forms a partition that divides the inside of the pressure vessel. As shown in FIG. 8, the disc portion has a hole 8B through which a refrigerant or a power supply lead wire passes. , 8C and 8D.
[0026]
In the present embodiment, the protection device 31 is disposed on the bearing plate 8. This protective device 31 has a protector body 32 having an opening / closing mechanism by a thermally responsive plate such as a bimetal in a metal hermetic container as in the above-described embodiment, and is made of a synthetic resin for holding the protector body 12. It consists of an electrically insulating holder. The holder further includes an external holder 33 and an internal holder 34, and the protector body 32 is combined with the cylindrical internal holder 34 before the external holder 33 is covered. Further, the holder 34A provided in the inner holder 34 is elastically fitted into the mounting hole 33A of the outer holder 33 so that the holder and the protector main body 32 are integrated to form the protection device 31. Further, the external holder 33 is provided with a through hole 33B for passing a terminal, and the terminals 32A, 32B, 32C of the protector body 32 are inserted therethrough.
[0027]
The external holder 33 includes a storage portion 33C for storing the protector body 32 and a passage portion 33D for guiding the refrigerant. The storage portion 33C and the passage portion 33D are connected to each other in the internal space. In this embodiment, flanges 33E and 33F having through holes for fixing are provided on the side surface of the storage portion 33C, and the protection device 31 is fixed on the bearing plate 8 by a method such as screwing.
[0028]
As described above, the bearing plate 8 has a plurality of through holes serving as refrigerant passages, and the protection device 31 is disposed so as to cover the through holes. In the embodiment, as shown in FIG. 9, the protective device 31 is attached so as to cover the two holes 8 </ b> B and 8 </ b> C serving as a refrigerant passage among the three through holes opened. Furthermore, lead wires 17 for connecting the electric motor 3 to an external power source via the sealed terminals 18 and connection wires 16 for connecting the protection device (not shown) are inserted into the remaining through holes 8D. The lead wire 17 is connected to the winding of the electric motor 3.
[0029]
When the refrigerant passes through the bearing plate 8, it passes through the gap with the inner surface of the pressure vessel and the through holes 8B, 8C, 8D. In the present invention, the protective device 31 covers the through holes 8B and 8C so that the external holder 33 of the protective device serves as a refrigerant passage, so that more refrigerant passes through the protective device. Furthermore, since the refrigerant introduced into the protection device passes while contacting the protector main body 32, the protector main body 32 can always be efficiently cooled during normal operation.
[0030]
Here, the refrigerant is introduced into the inner holder 34 from the through hole 8C of the bearing plate 8 as shown by a dotted line in FIG. 5 and hits the metal container of the protector main body 32. Further, the refrigerant passes through the gap between the inner surface of the external holder 34 and the protector main body 32 while coming into contact with the outer peripheral portion of the container, and is discharged into the storage portion 33C of the external holder 33, and is discharged into the pressure container through the through hole 33B. Head to. Further, the refrigerant introduced from the through hole 8B of the bearing plate 8 into the passage portion 33D of the external holder 33 flows into the storage portion 33C and comes out into the through hole 33B while being in contact with the terminal side surface of the protector body 32. To the discharge pipe 6.
[0031]
Here, in the present embodiment, a refrigerant passage that contacts the metal container of the protector 32 from the inner holder 34 in the outer holder and passes through the outer peripheral portion of the container, and a terminal side surface of the protector 32 from the passage portion 33D of the outer holder 33. And a refrigerant passage flowing therethrough is provided. In this way, by providing a plurality of refrigerant passages so that the refrigerant passing through each refrigerant passage hits a different surface of the protector body, the refrigerant stays around the protector so that the refrigerant contacts almost the entire surface of the protector. It becomes possible to exchange heat efficiently.
[0032]
In the above-described embodiments, the hermetic electric compressor has been described as an example. However, for example, a semi-hermetic electric compressor may be used as long as it has a high-pressure structure, and the refrigerant after heat exchange with the electric motor is possible. As long as it can be distributed, it is not limited to the embodiment.
[0033]
【The invention's effect】
As described above, according to the electric compressor of the present invention, the holder of the attached protection device is used as the refrigerant passage, so that the heat exchange relationship between the refrigerant and the protector body is improved. For this reason, the protector body is efficiently cooled by the refrigerant during normal operation, and the energizing current can be increased as compared with the conventional one. Therefore, a protective device that is slightly smaller than the conventional one can be used. The whole compressor can be reduced in size. Furthermore, by disposing the protective device in the opening of the discharge pipe or the partition wall that divides the inside of the container, it is possible to flow more refrigerant into the holder and to more efficiently exchange heat between the protector and the refrigerant.
[0034]
In addition, a plurality of refrigerant passages are provided in the holder so that the refrigerant passing through the respective passages hits different surfaces of the protector body from different directions, thereby generating a portion where the refrigerant stays on the downstream side of the protector body. Thus, the refrigerant and the protector can be efficiently contacted so that the refrigerant flows over the entire surface of the protector body. Therefore, not only when the amount of heat generated inside the protector increases due to overcurrent, but also when the heat of the protector is not removed due to overheating of the refrigerant or decrease in the amount of refrigerant, the temperature of the protector rises and the contact mechanism operates reliably. Can be made. Therefore, the operation of the protection device can be made more reliable.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an electric compressor of the present invention. FIG. 2 is an enlarged cross-sectional view showing attachment of a protection device in the electric compressor of FIG. 1. FIG. FIG. 4 is a cross-sectional view showing another embodiment of the electric compressor of the present invention. FIG. 5 is an enlarged cross-sectional view showing attachment of a protection device in the electric compressor of FIG. FIG. 7 is an exploded perspective view for explaining the protective device of FIG. 6. FIG. 8 is a cross-sectional view for explaining the electric compressor of FIG. 4. FIG. Sectional view showing the state of attaching [Explanation of symbols]
1, 2: 1: Electric compressor 2: Pressure vessel 3: Electric motor 4: Compressor 5: Suction pipe 6: Discharge pipe 7: Drive shaft 8: Bearing plate (partition wall)
10: Lubricating oil 11, 31: Protection device 12, 32: Protector body 13, 33: External holder 14, 34: Internal holder

Claims (4)

In a metal pressure vessel, provided with an electric motor and a compressor driven by this electric motor,
The refrigerant sucked from the outside of the pressure vessel is directly introduced into the compressor,
In the so-called high-pressure electric compressor, the refrigerant discharged from the compressor into the pressure vessel goes to the discharge pipe while exchanging heat with the electric motor through the gap of the electric motor.
A protective device is provided between the electric motor and the discharge pipe,
This protective device consists of a protector body with a metal airtight container and a holder for storing it.
An electric compressor characterized in that the holder of the protective device is a refrigerant passage, and the refrigerant is efficiently brought into contact with the protector body by collecting and flowing the refrigerant in the holder . The holder of the protection device is connected to the discharge pipe of the pressure vessel,
The electric compressor according to claim 1, wherein the refrigerant flows into the discharge pipe through the holder. A partition that divides the flow of refrigerant into upstream and downstream is provided in the pressure vessel,
This partition has a through-hole serving as a refrigerant passage,
The protective device is arranged on the partition in the pressure vessel,
A holder of the protective device is communicated with the through hole;
The electric compressor according to claim 1, wherein the refrigerant flows directly into the holder. Providing a plurality of refrigerant passages in the holder;
4. The refrigerant according to any one of claims 1 to 3, wherein the refrigerant passes through the entire surface of the protector main body by allowing the refrigerant passing through the refrigerant passages to contact different surfaces of the protector main body. The electric compressor as described.

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