JPH05231337A - Hermetic motor driven compressor - Google Patents

Abstract

PURPOSE:To reduce the number of times of motor stopping by controlling overload without stopping a motor at the time of temperature rise of discharge gas and to also protect the motor by stopping the motor in spite of the control of overload when the temperature of the coil of the motor rises improving reliability. CONSTITUTION:The temperature rising portion of a coil 5 in a stator 21 is provided with a first internal thermostat 71 to detect the temperature of the coil, and a second internal thermostat 72 is provided near the discharge port of a compression element 3. On the one hand, the temperature of the second internal thermostat 72 is set lower than the set temperature of the first internal thermostat 71, and on the other hand, a controller 40 is provided so as to output an overload control command by the activation of the second internal thermostat 72, and output a command to stop a motor 2 by the action of the first internal thermostat 71.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic electric compressor, and more particularly to a hermetic electric compressor in which a motor and a compression element driven by the motor are housed in a hermetic casing.

[0002]

2. Description of the Related Art Conventionally, as a hermetic electric compressor, for example, a motor C which is disclosed in Japanese Patent Application Laid-Open No. 2-86973 and which is installed in a hermetic casing B as shown in FIG.
The coil end D of the above is equipped with a current temperature sensitive overload protector A that is sensitive to the motor temperature and the refrigerant gas temperature and is sensitive to the overcurrent, and when the compressor is operated under overload, the protector A is installed. It is known that the motor C is operated to stop the operation of the motor C to prevent the motor from burning.

This protector A is fixed to one side of the coil end D of the motor C by a binding thread E, and the temperature of the motor temperature and the refrigerant gas temperature when the compressor is operated under overload. It detects abnormalities of rising,
The current flowing through the motor C is cut off by detecting the overcurrent of the motor C and the motor is stopped.

[0004]

However, in the above-mentioned conventional protector A, when the compressor is operated under an overload,
The motor C is operated in an abnormal state such as when an overcurrent flows or the gas is out of operation and the discharge gas temperature rises.
It is provided to stop the motor C, and thus stops the motor when an abnormality occurs due to overload operation,
Since the motor burnout is prevented, the number of times of stopping increases, and the number of times the refrigeration system starts and stops due to stopping the motor increases. Therefore, the reliability of the system is lowered, and the durability is lowered due to an increase in the number of times of starting and stopping the motor.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to suppress the temperature rise of a motor by performing overload control when the discharge gas temperature rises. An object of the present invention is to provide a hermetic electric compressor capable of reducing the number of times of stoppage due to overload of the motor, improving the reliability thereof, and improving the durability of the compressor.

[0006]

According to the present invention, in order to achieve the above object, a motor 2 including a stator 21 and a rotor 22 is disposed on one side of a hermetically sealed casing 1, and the motor 2 is In the hermetic electric compressor in which the compression element 3 that is interlockingly connected to the extending drive shaft 4 is disposed on the other side, the temperature of the coil 21 in the stator 21 is increased to the highest temperature.
A first internal thermostat 71 for detecting the coil temperature is provided, and a second internal thermostat 72 for detecting the discharge gas temperature is provided near the discharge port of the compression element 3, and the second internal thermostat 72 is provided.
The set temperature of the first internal thermostat 71
Control device 40 that outputs an overload control command by operating the second internal thermostat 72 and outputs an operation stop command of the motor 2 by operating the first internal thermostat 71 while lowering the set temperature below Is provided.

[0007]

When the discharge gas temperature rises to the temperature at which the compressor element 3 is burned due to the gas shortage operation, the second internal thermostat 72 provided near the discharge port of the compression element 3 discharges the gas. Sensing the gas temperature,
The control device 40 outputs an overload control command by this operation, and for example, the rotation speed of the motor 2 is decreased, the air volume of the condenser fan is increased, or liquid injection is performed. The load is controlled. Therefore, the seizure of the compression element 3 can be prevented, and the coil temperature of the motor 2 can be prevented from rising, so that the number of times the motor 2 is stopped due to overload operation can be reduced. The number of times the refrigeration system is stopped can be reduced accordingly. Therefore, the reliability can be improved and the durability of the motor 2 can be improved. When the coil temperature of the motor 2 rises to the temperature at which the motor burns out despite the overload control performed by the operation of the second internal thermostat 72, the operation of the first internal thermostat 71 is performed. Since the motor 2 can be stopped, burnout of the motor 2 can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hermetic electric compressor according to the present invention will be described below with reference to the drawings. The hermetic electric compressor shown in FIG. 1 is a horizontal twin compressor that can be controlled by an inverter and is used in a refrigeration system. Although one shown in FIG. 1 omits one compressor. , Oblong cylinder 1
1 and 1 which are capped on the openings on both sides in the length direction of the tubular body 11.
A closed casing 1 is formed with a pair of lids 12, and the motors 2 are respectively attached to the respective lids 12 in the casing 1.
Further, the compression elements 3 are arranged on the central portion side of the tubular body 11, respectively, and the compression elements 3 are rotationally driven via the drive shafts 4 of the motors 2. Refrigerant gas is discharged from each of the compression elements 3 and is connected to the central portion of the cylindrical body 11 in the longitudinal direction.
The discharge gas from 3 is discharged to the outside of the casing. One compressor side shown in FIG. 1 will be described below.

The motor 2 is composed of a stator 21 fixed to the inner wall of the cylindrical body 11 and a rotor 22 arranged in the stator 21, and the side of the coil 5 installed in the stator 21 opposite to the compression element side. A plurality of lead wires 52 drawn out from the coil end 51 are respectively connected to a plurality of electric motor main circuit terminals 61, ...
The rotation speed can be adjusted by frequency control via the inverter controller 41.

Therefore, according to the present invention, in the hermetic electric compressor described above, the coil 5 in the stator 21 is
A first internal thermostat 71 for detecting the coil temperature is provided at the temperature rising portion, that is, the lead wire side, and the discharge gas temperature is detected near the discharge port of the compression element 3, in other words, on the opposite lead wire side. A second internal thermostat 72 is provided so that the set temperature of the second internal thermostat 72 is lower than the set temperature of the first internal thermostat 71, while the second internal thermostat 72 is set to the second internal thermostat 72.
The control device 40 is provided which outputs an overload control command by the operation of the internal thermostat 72 and outputs an operation stop command of the motor 2 by the operation of the first internal thermostat 71.

In the embodiment shown in FIG. 1, the first internal thermostat 71 is arranged at the lead wire side of the stator 21, that is, at the coil end 51 on the side opposite to the compression element, and the first internal thermostat 71 is provided. Is connected to the first internal thermostat terminal 62 provided on the lid 12 via the lead wire 53, and the first internal thermostat terminal 62 is connected to the input side of the control device 40 described later. is there. The operating temperature of the first internal thermostat 71 is, for example, 1
It is set to 50 ° C. Therefore, when the coil temperature on the side of the lead wire reaches 150 ° C., the first internal thermostat 71 operates, and is disposed outside the hermetic casing 1 of the compressor via the first internal thermostat terminal 62. The coil temperature signal on the side of the lead wire is input to the control device 40 that operates, and an operation stop command is output from the control device 40 to the switch 42 provided in the main circuit of the motor 2 by the input of this temperature signal. Then, the motor 2 is stopped. It should be noted that the first internal thermostat 71 is disposed on the anti-compression element side coil end 51 because the coil end 51 on the compression element side is disposed.
Is located in the path of the discharge gas discharged from the compression element 3 to the discharge pipe 13, and is cooled by this discharge gas, while the discharge pipe 13 is connected to the central portion of the tubular body 11. Therefore, the discharge gas does not easily flow to the anti-compression element side, and therefore the anti-compression element side coil end 51
Is difficult to be cooled and the coil temperature becomes high. By providing the coil at this position, the highest temperature can be detected and the motor 2 can be stopped, so that the motor burnout can be more surely prevented. ..

The second internal thermostat 72 is arranged at the coil end 51 on the compression element side near the discharge port of the discharge gas discharged from the compression element 3, and the second internal thermostat 72 is provided. Is connected to the second internal thermostat terminal 63 provided on the lid 12 via the lead wire 54, and the second internal thermostat terminal 63 is also connected to the control device 40. The operating temperature of the second internal thermostat 72 is lower than the operating temperature of the first internal thermostat 71, for example, 1
The temperature is set to about 40 ° C., and when the second internal thermostat 72 is operating, the temperature signal of the discharge gas temperature is output to the outside of the hermetic casing 1 of the compressor via the second internal thermostat terminal 62. It is input to the control device 40 arranged in the above, and by this input, the overload control command is output from the control device 40. In this overload control, for example, the frequency of the motor 2 is controlled to a low frequency to reduce the rotation speed, or the rotation of the fan attached to the condenser in the refrigeration system is increased,
The amount of air is increased or liquid injection is performed in the compression chamber of the compression element 3, and when the rotation speed of the motor 2 is reduced, the output side of the control device 40 is operated. The inverter controller 41 is connected, and the controller 43 of the fan motor that controls the rotation speed of the fan is connected when increasing the air volume. Further, when the liquid injection is performed, the liquid controller is connected. The solenoid valve 44 is connected to the injection tube (not shown).

The second internal thermostat 72
Is set to a temperature of around 140 ° C., the discharge gas temperature rises, the coil temperature of the motor 2 rises, and the temperature of the discharge gas increases before the first internal thermostat 71 operates. This is for lowering and stopping the motor 2.

Thus, the hermetic electric compressor of the present invention is
When the discharge gas temperature becomes higher than the operating temperature of the second internal thermostat 72 due to a gas shortage operation or the like, the second internal thermostat 72 operates to output an overload control command from the control device 40, and Overload control is performed such that the rotation speed of the motor 2 is reduced, the air volume is increased, and liquid injection is performed. Therefore, by this overload control, the rise in the discharge gas temperature can be suppressed, and as a result, the rise in the coil temperature of the motor 2 can also be suppressed, and the first internal thermostat 71 operates to operate the motor 2 Can be prevented from stopping.
Therefore, the number of times the motor 2 is stopped can be reduced, the number of times the refrigeration system is started and stopped can be reduced, the reliability thereof can be improved, and the durability of the motor 2 can also be improved. If there is a case where the increase in the discharge gas temperature cannot be suppressed even by the overload control, the first
The internal thermostat 71 operates and the motor 2 can be stopped, and since the first internal thermostat 71 is arranged at the highest temperature rising portion of the coil 5, the motor 2 burns. The motor 2 can be surely stopped before.

Further, the first internal thermostat 71 used in the hermetic electric compressor of the present invention performs the open-phase operation in order to prevent the compressor from sleeping when the compressor is stopped by the inverter control. It can also be used as a safety device when the motor 2 is heated to keep the inside of the closed casing 1 warm. That is, when the temperature of the coil 5 of the motor 2 rises above the operating temperature of the first internal thermostat 71 during the open phase operation, the open phase operation of the motor 2 can be stopped. Also, the seizure of the motor 2 can be prevented.

[0016]

As described above, in the hermetic electric compressor according to the present invention, the first internal thermostat 71 for detecting the coil temperature is provided at the highest temperature rising portion of the coil 5 in the stator 21. A second internal thermostat 72 for detecting the discharge gas temperature is provided near the discharge port of the compression element 3, and the set temperature of the second internal thermostat 72 is made lower than the set temperature of the first internal thermostat 71. The second
Since the control device 40 that outputs the overload control command by the operation of the internal thermostat 72 and outputs the operation stop command of the motor 2 by the operation of the first internal thermostat 71 is provided, the discharge gas due to the gas shortage operation or the like is provided. When the temperature rises and becomes equal to or higher than the operating temperature of the second internal thermostat 72, the operation of the second internal thermostat 72 causes the control device 40 to operate.
Since the overload control command is output from, the overload control can be performed. Therefore, by performing this overload control, it is possible to suppress the rise in the coil temperature of the motor 2, and thus it is possible to suppress the stop of the motor 2 by the first internal thermostat 71, and to reduce the number of times the motor 2 is stopped. Therefore, the number of times the refrigeration system is stopped can be reduced accordingly, the reliability thereof can be improved, and the durability of the motor 2 can be improved. Further, when the coil temperature of the motor 2 rises because the rise of the discharge gas temperature cannot be suppressed despite the overload control, the first internal thermostat 71 operates to stop the motor 2. Can be done.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hermetic electric compressor according to the present invention.

FIG. 2 is a front view of the hermetic electric compressor of FIG.

FIG. 3 is a partial switching cross-sectional view of a hermetic electric compressor showing a conventional example.

[Explanation of symbols]

 1 Closed Casing 2 Motor 21 Stator 22 Rotor 3 Compression Element 4 Drive Shaft 5 Coil 40 Control Device 71 First Internal Thermostat 72 Second Internal Thermostat

Claims (1)

[Claims] 1. A stator 2 is provided on one side in a closed casing 1.
1 and a motor 22 composed of a rotor 22 are arranged,
A hermetic electric compressor having a compression element (3) interlockingly connected to a drive shaft (4) extending from the motor (2) arranged on the other side. 1 internal thermostat 71
And a second internal thermostat 72 for detecting the discharge gas temperature near the discharge port of the compression element 3.
Is provided to make the set temperature of the second internal thermostat 72 lower than the set temperature of the first internal thermostat 71, while outputting an overload control command by the operation of the second internal thermostat 72, and By the operation of 1 internal thermostat 71,
A hermetic electric compressor provided with a control device 40 for outputting an operation stop command of the motor 2.