JP6064481B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly, to an air conditioner having an internal low-pressure compressor incorporated in a sealed container in a refrigeration cycle.

  A refrigerant compressor used in a refrigeration cycle of an air conditioner is generally configured as a hermetic compressor integrated with a motor and contained in a hermetic container. This compressor compresses the refrigerant introduced into the sealed container and discharges it to the refrigerant circulation path.

  In such a hermetic compressor, in order to prevent an abnormal temperature rise of the motor, a bimetal switch type overload protector (OLP: Over Load Protector) is installed in the airtight container near the motor winding. There is something that has become. The overload protector is configured such that when the bimetal switch is turned on / off according to the temperature of the motor winding and the motor winding is overheated, the overload protector is turned off to cut off the energization of the motor winding.

  By the way, when installing the air conditioner, the refrigerant is filled in the refrigeration cycle. At this time, air may be mixed into the refrigerant due to a construction error or the like.

  However, when the overload protector operates in such a state that air is mixed in the refrigerant, if a flammable refrigerant is used, the spark generated when the overload protector is turned on / off The refrigerant may ignite.

  By the way, there are an internal high-pressure type and an internal low-pressure type, but the internal high-pressure type compressor is filled with high-pressure gas refrigerant pressurized by the compressor in the internal high-pressure type compressor. The temperature of the motor is easily transmitted to the sealed container. As a result, when the motor winding is overheated, the airtight container also becomes high temperature.

  For this reason, for example, as disclosed in Patent Document 1, it is possible to detect the overheating state of the motor winding even when the overload protector is externally attached to the sealed container. Therefore, by externally attaching the overload protector to the sealed container in this way, it is possible to prevent the refrigerant from being ignited even if a spark occurs when the overload protector is turned on / off.

Japanese Patent Laid-Open No. 10-274168

  However, in an internal low-pressure compressor in which the inside of the sealed container is filled with low-pressure gas refrigerant, the temperature of the motor winding is difficult to be transmitted to the sealed container, and the temperature of the sealed container is lower than the temperature of the motor winding (for example, −50 deg. Or more). For this reason, when an overload protector is externally attached to the hermetic container, the temperature of the motor winding cannot be accurately detected, making it difficult to protect the compressor.

  Therefore, the present invention has been made in view of the above problems, and even when an internal low-pressure compressor is used, the temperature of the motor winding can be accurately detected, and the overload protector can be operated. An air conditioner that can prevent the refrigerant from igniting even when a spark occurs is provided.

  The air conditioner of the present invention is an air conditioner having an internal low-pressure type compressor incorporating a motor in a sealed container, and having a refrigeration cycle using a flammable or slightly flammable refrigerant, A motor power line for supplying power from the power source to the motor, a power switch provided on the motor power line for turning on / off the power supply for driving the motor, and the power switch provided for the same power source when energized A coil that turns on the switch, the coil is connected, a low current wiring that is a separate circuit from the motor power line, and a coil connected to the low current wiring and provided near the motor winding in the sealed container And a temperature protection switch that turns off when the motor winding reaches a predetermined temperature or more, and turns on / off the power switch in conjunction with the on / off of the temperature protection switch. And wherein the door.

In the above invention, the current flowing through the motor power supply line and the low current wiring is supplied from the power supply.

  According to the present invention, the temperature of the motor winding can be accurately detected by arranging the temperature protection switch near the motor winding in the sealed container. At this time, the temperature protection switch is supplied with a current from the power supply by the low current wiring, and a current less than a current value that generates a spark when the temperature protection switch is turned on / off is applied to the low current wiring. Therefore, even if the temperature protection switch is placed in an airtight container filled with flammable or slightly flammable refrigerant, the temperature protection switch will not generate sparks, preventing the refrigerant from igniting by sparks. it can.

  Further, the low current wiring is connected to a coil terminal of a power switch provided on the motor power line of the compressor. As a result, the power switch is turned on / off in conjunction with the temperature protection switch being turned on / off, so when the temperature protection switch detects overheating of the motor winding, the power switch cuts off the power to the motor power line. The motor can be stopped and the compressor can be protected.

FIG. 1 is a schematic configuration diagram showing an embodiment of an air-conditioning apparatus of the present invention. FIG. 2 is an enlarged cross-sectional view of a compressor used in the air conditioner shown in FIG. FIG. 3 is a schematic motor wiring diagram of the compressor shown in FIG. FIG. 4 is a schematic motor wiring diagram showing another embodiment of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the air conditioning apparatus 1 of the present embodiment includes a refrigeration cycle 6 having a compressor 2, an outdoor heat exchanger 3, a decompression unit 4, and an indoor heat exchanger 5. As the decompression means 4, an expansion valve or a capillary tube is generally used. The air conditioner 1 is normally capable of cooling and heating, and the refrigeration cycle 6 is provided with a four-way valve 7 on the discharge side of the compressor 2 for switching between cooling and heating.

  When the air conditioner 1 cools the room, a flow path is formed along the solid line in the four-way valve 7 in the figure, and the refrigerant discharged from the compressor 2 is supplied to the outdoor heat exchanger 3. The refrigerant is circulated in the direction a in the figure. On the other hand, when heating the room, a flow path is formed along the broken line in the four-way valve 7 in the figure, and the refrigerant discharged from the compressor 2 is supplied to the indoor heat exchanger 5, and the refrigerant is shown in the figure. It is circulated in the b direction.

  Therefore, when the room is cooled by the air conditioner 1, the high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 2 is cooled by the outdoor heat exchanger 3 to form a high-pressure liquid-phase refrigerant, and this refrigerant is decompressed. After adiabatic expansion at 4 and the pressure and temperature are lowered, it is vaporized by the indoor heat exchanger 5 to form a gas-phase refrigerant and returned to the compressor 2. In this case, the outdoor heat exchanger 3 functions as a condenser, and the indoor heat exchanger 5 functions as an evaporator. As a result, the low-temperature and low-pressure refrigerant exchanges heat with the indoor air in the indoor heat exchanger 5 to perform the cooling operation.

  On the other hand, when the room is heated by the air conditioner 1, the high-temperature and high-pressure gas phase refrigerant discharged from the compressor 2 is cooled by the indoor heat exchanger 5, contrary to the case of cooling. The refrigerant is adiabatically expanded by the decompression means 4 to lower the pressure and temperature, and then vaporized by the outdoor heat exchanger 5 to be vapor phase refrigerant and returned to the compressor 2. In this case, the outdoor heat exchanger 3 functions as an evaporator, and the indoor heat exchanger 5 functions as a condenser. As a result, the high-temperature and high-pressure refrigerant exchanges heat with room air in the indoor heat exchanger 5 to perform heating operation.

  Incidentally, in the compressor 2 of the present embodiment, as shown in FIG. 2, the refrigerant compression unit 210 and the motor 220 that drives the compression unit 210 are integrated and housed in the hermetic container 230.

  In the present embodiment, a flammable or slightly flammable refrigerant is used as the refrigerant circulating in the refrigeration cycle 6 in order to increase the refrigeration efficiency. Examples of the flammable or slightly flammable refrigerant include R32, R1234yf, R1234ze, R290 (propane), R161, R152a, a mixed refrigerant of R1234yf and R32, a mixed refrigerant of R1234ze and R32.

  Next, the structure of the compressor 2 will be described. In the description of the compressor 2, the upper side in the figure is the upper side, and the lower side in the figure is the lower side.

  The sealed container 230 of the compressor 2 has a cylindrical shape whose both ends are closed by upper and lower closing plates 231 and 232. Inside the hermetic container 230, the compression unit 210 is disposed above the partition wall 233 fixed to the hermetic container 230, and the motor 220 that drives the compression unit 210 is disposed below. At this time, the inside where the compression unit 210 is arranged with the partition wall 233 as a boundary is the compression unit arrangement chamber R1, and the inside where the motor 220 is arranged is the motor arrangement chamber R2.

  In this embodiment, the compression unit 210 is configured as a scroll compressor. The scroll compressor has a pair of spiral bodies 211 and 212 having the same shape, and the compression section 210 is configured so that the spiral bodies 211 and 212 are reversed with respect to each other and partially in close contact with each other. It is what you are doing.

  The refrigerant sucked from the outer peripheral side of the compression unit 210 is guided toward the center while being compressed in the compression unit 210. Thereafter, the high-temperature and high-pressure refrigerant that has flowed out upward of the compression unit 210 is led out to the discharge pipe 241.

  The motor 220 includes an annular stator 221 that is press-fitted and fixed to the inner periphery of the hermetic container 230, and a rotor 222 that is rotatably fitted with a slight gap δ provided on the inner periphery of the stator 221.

  A motor winding 223 is wound around the stator 221, and the rotor 222 is formed of a permanent magnet in which a plurality of N poles and S poles are alternately magnetized at equal intervals on the outer periphery. The rotor 222 is rotated by applying a current to the motor winding 223. Further, a temperature protection switch 11 that opens and closes a contact point according to the temperature of the motor winding 223 is fixed to the motor winding 223.

  A rotation output shaft 224 passes through the rotation center of the rotor 222 so as to rotate integrally with the rotor 222. The upper end portion of the rotation output shaft 224 is rotatably supported by a bearing portion B1 provided on the partition wall 233. The spiral body 212 is eccentrically rotated by the rotation of the rotation output shaft 224, whereby the compression unit 210 compresses the refrigerant.

  As shown in FIG. 1, the compressor 2 configured in this way has a refrigerant introduction pipe 240 connected to the middle part of the sealed container 230 and a refrigerant discharge pipe 241 connected to the upper end of the sealed container 230. The The refrigerant sucked into the sealed container 230 from the refrigerant introduction pipe 240 is compressed by the compression unit 210 and discharged from the refrigerant discharge pipe 241.

  As shown in FIG. 2, the refrigerant introduction pipe 240 is communicated with a position corresponding to the communication path 237 between the compression section arrangement chamber R1 and the motor arrangement room R2, and the refrigerant discharge pipe 241 is connected to the compressor 2 The upper part, in short, communicates with a position corresponding to the discharge side of the compression unit 210.

  Therefore, the refrigerant guided to the compression unit arrangement chamber R1 is directly taken into the compression unit 210 and compressed. On the other hand, the refrigerant guided to the motor arrangement chamber R <b> 2 is filled in the motor arrangement chamber R <b> 2, and then supplied to the compression unit arrangement chamber R <b> 1 through the communication path 237 and taken into the compression unit 210. At this time, since the motor arrangement chamber R2 is filled with the low-pressure refrigerant, the compressor 2 of the present embodiment is an internal low-pressure type.

  FIG. 3 shows a circuit diagram of the motor winding 223 of the motor 220, and in this embodiment, shows a case of a single-phase motor having S contact, R contact, and C contact. A motor power line Hc is connected to the C contact, a motor power line Hr is connected to the R contact, and a motor power line Hs branched from the motor power line Hr is connected to the S contact.

  Then, when the power supply 10 of the air conditioner 1 is turned on, current is applied to the motor power supply lines Hc, Hr, and Hs. Thereby, the rotor 222 of a permanent magnet rotates and the compressor 2 is driven, and the refrigerant is circulated through the refrigeration cycle 6.

  Here, in this embodiment, as shown in FIG. 3, the power supply relay 12 is arranged on the motor power supply line Hc, and the power supplied to the motor 220 by the power supply relay 12 can be turned on / off. The power relay 12 has a normally open power switch 12a and an electromagnetic coil 12b. A motor power line Hc is connected to the contact terminals T1 and T2, and a low current wiring Hl is connected to the coil terminals T3 and T4. The

  The low current wiring Hl connected to the coil terminals T3 and T4 is connected to the power source 10 and is a circuit different from Hc, Hr and Hs. Moreover, since the low current wiring Hl has the electromagnetic coil 12b which is a resistor, the current flowing through the low current wiring has a low value (low current).

  In this embodiment, power is supplied from the power source 10 to the low current wiring H1, but the power source that supplies power to the low current wiring H1 may be a separate power source.

  Furthermore, in this embodiment, as shown in FIG. 3, the temperature protection switch 11 is disposed in the vicinity of the motor winding 223 in the sealed container 230, and the temperature of the motor winding 223 can be directly detected by the temperature protection switch 11. It is like that.

  In the present embodiment, the temperature protection switch 11 is shown in the state of being arranged in the vicinity of the motor winding 223 connected to the C contact. Or another motor winding 223 connected to the R contact. The temperature protection switch 11 is a bimetal switch type as in the conventional case, and is turned on when the detected temperature is lower than the set temperature and turned off when the detected temperature is higher than the set temperature.

  The temperature protection switch 11 is supplied with a current by a low current wiring H1 connected to the power supply 10. The low current wiring Hl needs to limit the current flowing through the temperature protection switch 11 so that no spark is generated when the temperature protection switch 11 is turned on / off. As described above, the low current wiring Hl is a resistor. Since the electromagnetic coil 12b is provided, the current flowing through the low current wiring has a low value (low current). Further, as a means for reducing the current flowing through the low current wiring Hl, for example, a constant current diode (CRD: Current Regulative Diode) (not shown) may be used.

  Incidentally, it has been confirmed that a condition for generating a spark when the temperature protection switch 11 is turned on / off is a case where power exceeding 5 kVA is applied to the temperature protection switch 11. Therefore, it is only necessary to set the resistance value of the electromagnetic coil 12b so that the power value applied to the low current wiring H1 is 5 kVA or less.

  Therefore, when the temperature protection switch 11 is turned on, the power relay 12 is turned on when the electromagnetic coil 12b is excited, and when the temperature protection switch 11 is turned off, the electromagnetic coil 12b is demagnetized and turned off, thereby cutting off the motor power line Hc. It is like that. Thereby, when the load of the compressor 2 becomes excessive and the motor winding 223 is overheated, the temperature protection switch 11 detects this, and the power supply relay 12 is turned off to stop the motor 220, thereby compressing. Machine 2 is stopped. In addition, although the case where the power supply relay 12 was provided in the motor power supply line Hc was shown, it can be made to function similarly also when provided in other motor power supply lines Hr and Hs without being restricted to this.

  Further, in the present embodiment, the overcurrent protection relay 13 is provided in the motor power line Hr, and when the overcurrent flows through the motor winding 133, the overcurrent protection relay 13 cuts off the motor power line Hr. Thus, the motor 220 (compressor 2) is stopped. Further, an operating capacitor 14 is provided on the motor power line Hs, and a rotating magnetic field is generated by shifting the phase.

  As described above, according to the air conditioner 1 of the present embodiment, the temperature protection switch 11 is disposed in the vicinity of the motor winding 223 in the sealed container 230 of the compressor 2. Then, a current is supplied from the power source 10 by the low current wiring H1 connected to the temperature protection switch 11, but the low current wiring H1 has a value less than a current value at which a spark is generated when the temperature protection switch 11 is turned on / off. An electric current, that is, a current that does not generate a spark flows.

  Therefore, by arranging the temperature protection switch 11 in the vicinity of the motor winding 223 in the sealed container 230, overheating of the motor winding 223 can be detected with high accuracy. The airtight container 230 is filled with a flammable or slightly flammable refrigerant. Even when the temperature protective switch 11 is disposed in the airtight container 230, the temperature protective switch 11 is turned on / off. Since no spark is generated, the refrigerant in the sealed container 230 can be prevented from igniting.

  Further, according to the present embodiment, the power supply relay 12 is provided on the motor power supply line Hc of the compressor 2, and the low current wiring Hl is connected to the coil terminals T3 and T4 of the power supply relay 12. Thereby, since the power relay 12 is turned on / off in conjunction with the on / off of the temperature protection switch 11, when the temperature protection switch 11 detects overheating of the motor winding 223, the power relay 12 is switched to the motor power source. The energization of the line Hc is cut off. Therefore, since the motor 220 can be stopped by interrupting the motor power line Hc in this way, the compressor 2 can be safely protected.

  Further, in the present embodiment, a single-phase motor has been described in detail as an example, but the same effect can be achieved even in the case of a three-phase motor as shown in FIG. In this case, the motor 220 is a three-phase motor having a contact U, a contact V, and a contact W. The contact U is connected to the motor power line Hu, the contact V is connected to the motor power line Hv, and the contact W is connected to the motor power line. It is connected to the inverter 15 via Hw. The inverter 15 controls the rotation speed of the motor 220. The inverter 15 is connected to the power supply 10 via the power supply line 16 and the power supply line 17.

  Here, as shown in FIG. 4, a power supply relay 12 is arranged on the power supply line 16, and the power supplied to the motor can be turned on / off by the power supply relay 12. The operation of the power supply relay 12 is the same as that of the example of the single-phase motor in FIG.

  The preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, although the scroll compressor is shown as the compression unit 210, the present invention can be applied to a compressor using other compressors such as a rotary compressor as long as it is an internal low pressure type.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Compressor 6 Refrigeration cycle 10 Power supply 11 Temperature protection switch 12 Power supply relay 12a Power switch 12b Electromagnetic coil 210 Compression part 220 Motor 223 Motor winding 230 Sealed container Hl Low current wiring Hc Motor power supply line T3, T4 Power supply relay Coil terminal

Claims (2)

An air conditioner having an internal low-pressure compressor that incorporates a motor in a sealed container, and having a refrigeration cycle using a flammable or slightly flammable refrigerant,
A motor power line for supplying power from a power source to the motor;
A power switch provided on the motor power line for turning on / off power supply for driving the motor;
A coil that is provided in the power switch and turns on the power switch when energized;
Low current wiring that is connected to the coil and is a separate circuit from the motor power line,
A temperature protection switch connected to the low current wiring, provided near the motor winding in the sealed container, and turned off when the motor winding becomes a predetermined temperature or more;
An air conditioner that turns on and off the power switch in conjunction with turning on and off the temperature protection switch. The air conditioner according to claim 1, wherein a current flowing through the motor power supply line and the low current wiring is supplied from the power supply.

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