Refrigeration cycle apparatus

• US 20030213256A1
• Filed: 04/03/2003
• Published: 11/20/2003
• Est. Priority Date: 04/04/2002
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yoshida, Makoto, Yakumaru, Yuuichi, Ueda, Mitsuo
• Granted Patent: US 6,868,686 B2
• Time in Patent Office: Days
• US Class Current: 62/230
• CPC Class Codes: F25B 1/02 with compressor of reciprocating-piston type F25B1/005, F25B1/10 take precedence
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2313/0315 Temperature sensors near the outdoor heat exchanger
• CPC Class Codes: F25B 2400/073 Linear compressors
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 2700/2104 of an indoor room or compartment
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 2700/21172 at the inlet
• CPC Class Codes: F25B 30/02 of the compression type
• CPC Class Codes: F25B 49/022 Compressor control arrangements
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A refrigeration cycle apparatus having a linear compressor is provided with a volume circulation rate instruction unit for obtaining a volume circulation rate Vco of a refrigerant in accordance with refrigerating capacity required of the refrigeration cycle apparatus, on the basis of an ambient temperature of an indoor heat exchanger (evaporator), a target temperature set on the evaporator by the user, and an ambient temperature of an outdoor heat exchanger (condenser); a volume circulation rate detector for detecting a volume circulation rate Vcd of the refrigerant that actually circulates in a refrigerant circulation path of the refrigeration cycle apparatus; and an inverter for generating an AC current for driving the linear compressor; wherein the inverter is controlled so as to decrease a difference between the volume circulation rate Vco and the volume circulation rate Vcd.

Claims

1. A refrigeration cycle apparatus including a first heat exchanger and a second heat exchanger which form a circulation path for a refrigerant, and a linear compressor having a piston and a linear motor which makes the piston reciprocate, and circulating a refrigerant in the circulation path by the reciprocating motion of the piston, said apparatus comprising:

an inverter for generating an AC current for driving the linear motor;

an actual circulation rate detector for detecting an actual refrigerant circulation rate indicating the volume of the refrigerant that is discharged from or sucked into the linear compressor per unit time by the reciprocating motion of the piston;

a target circulation rate derivation unit for deriving a target refrigerant circulation rate indicating the volume of the refrigerant to be discharged from or sucked into the linear compressor per unit time, on the basis of an ambient temperature of at least one of the first heat exchanger and the second heat exchanger, and a target temperature that is set for at least one of the heat exchangers; and

a controller for controlling the operation of the inverter so as to decrease a difference between the actual refrigerant circulation rate and the target refrigerant circulation rate.

2. A refrigeration cycle apparatus as defined in claim 1 further comprising:

a stroke detector for detecting the stroke length of the reciprocating piston;

a top dead point detector for detecting the top dead point of the reciprocating piston; and

said actual circulation rate detector calculating the volume of the refrigerant that is discharged or sucked by each reciprocating motion of the piston, on the basis of the detected stroke length and the detected top dead point, and multiplying the calculated volume by the frequency of the AC current generated by the inverter, thereby to obtain the actual refrigerant circulation rate.

3. A refrigeration cycle apparatus as defined in claim 2 further comprising:

a discharge pressure estimation unit for estimating the pressure of the refrigerant to be discharged from the linear compressor, on the basis of the temperature of the refrigerant in the heat exchanger for condensing the refrigerant, said estimation unit being positioned on the refrigerant discharge side of the linear compressor;

a suction pressure estimation unit for estimating the pressure of the refrigerant to be sucked into the linear compressor, on the basis of the temperature of the refrigerant in the heat exchanger for evaporating the refrigerant, said estimation unit being positioned on the refrigerant suction side of the linear compressor; and

said actual circulation rate detector performing an arithmetic operation using a pressure ratio between a maximum pressure and a minimum pressure of the refrigerant in the circulation path, which is obtained from the estimated pressure of the refrigerant to be sucked and the estimated pressure of the refrigerant to be discharged, and the detected stroke length and the detected top dead point, thereby to obtain the volume of the refrigerant to be discharged or sucked by each reciprocating motion of the piston.

10. An air conditioner having a refrigeration cycle apparatus as defined in any of claims 1 to 9, wherein

said first heat exchanger is an outdoor heat exchanger, and

said second heat exchanger is an indoor heat exchanger.

11. A refrigerator having a refrigeration cycle apparatus as defined in any of claims 1 to 9, wherein

said first heat exchanger is a condenser for discharging heat, and

said second heat exchanger is an evaporator for cooling the inside of the refrigerator.

12. A hot-water supply unit having a refrigeration cycle apparatus as defined in any of claims 1 to 9, including

a storage tank for storing water,

wherein said first heat exchanger is a water heat exchanger for heating the water stored in the tank, and

said second heat exchanger is an air heat exchanger for absorbing heat from the surrounding atmosphere.

13. A cryogenic freezer having a refrigeration cycle apparatus as defined in any of claims 1 to 9, including

a freezing chamber,

wherein said first heat exchanger is a heat radiator for radiating heat, and

said second heat exchanger is a heat storage for cooling the inside of the freezing chamber.

4. A refrigeration cycle apparatus having a first heat exchanger and a second heat exchanger which form a circulation path for a refrigerant, and a linear compressor having a piston and a linear motor which makes the piston reciprocate, and circulating the refrigerant in the circulation path by the reciprocating motion of the piston, said apparatus comprising:

an inverter for generating an AC current for driving the linear motor;

an actual circulation rate detector for detecting an actual refrigerant circulation rate indicating the weight of the refrigerant that is discharged from or sucked into the linear compressor per unit time by the reciprocating motion of the piston;

a target circulation rate derivation unit for deriving a target refrigerant circulation rate indicating the weight of the refrigerant to be discharged from or sucked into the linear compressor per unit time, on the basis of an ambient temperature of at least one of the first heat exchanger and the second heat exchanger, and a target temperature that is set for at least one of the heat exchangers; and

a controller for controlling the operation of the inverter so as to decrease a difference between the actual refrigerant circulation rate and the target refrigerant circulation rate.

5. A refrigeration cycle apparatus as defined in claim 4 further comprising:

a stroke detector for detecting the stroke length of the reciprocating piston;

a top dead point detector for detecting the top dead point of the reciprocating piston;

a discharge refrigerant concentration detector for detecting the concentration of the refrigerant discharged from the linear compressor; and

said actual circulation rate detector calculating the volume of the refrigerant that is discharged by each reciprocating motion of the piston, on the basis of the detected stroke length and the detected top dead point, and obtaining the weight of the refrigerant that is discharged from the linear compressor per unit time, on the basis of the calculated volume, the detected concentration of the refrigerant, and the frequency of the AC current generated by the inverter.

6. A refrigeration cycle apparatus as defined in claim 5 further comprising:

a discharge temperature detector for detecting the temperature of the refrigerant discharged from the linear compressor;

a discharge pressure detector for detecting the pressure of the refrigerant discharged from the linear compressor; and

said discharge refrigerant concentration detector deriving the concentration of the refrigerant discharged from the linear compressor, on the basis of the detected temperature and pressure of the refrigerant.

7. A refrigeration cycle apparatus as defined in claim 4 further comprising:

a stroke detector for detecting the stroke length of the reciprocating piston;

a top dead point detector for detecting the top dead point of the reciprocating piston; and

said actual circulation rate detector calculating the volume of the refrigerant discharged by each reciprocating motion of the piston, on the basis of the detected stroke length and the detected top dead point, and obtaining the weight of the refrigerant sucked into the linear compressor per unit time, on the basis of the calculated volume, the detected concentration of the refrigerant, and the frequency of the AC current generated by the inverter.

8. A refrigeration cycle apparatus as defined in claim 7 further including:

a suction temperature detector for detecting the temperature of the refrigerant sucked into the linear compressor;

a suction pressure detector for detecting the pressure of the refrigerant sucked into the linear compressor; and

said suction refrigerant concentration detector obtaining the concentration of the refrigerant sucked into the linear compressor, on the basis of the detected temperature and pressure of the refrigerant.

9. A refrigeration cycle apparatus as defined in claim 8 further including:

a refrigerant temperature detector for detecting the temperature of the refrigerant in an evaporator which is a heat exchanger for evaporating the refrigerant, as a saturation temperature of the refrigerant sucked into the linear compressor, said detector being positioned at the refrigerant suction side of the linear compressor in the circulation path;

a super heat estimation unit for estimating the super heat of the refrigerant, which is a temperature difference between the temperature of the refrigerant sucked into the linear compressor and the saturation temperature thereof, on the basis of the operating state of the linear compressor; and

said suction temperature detector obtaining the temperature of the temperature of the refrigerant sucked into the linear compressor, by adding the detected temperature of the refrigerant in the evaporator and the estimated super heat of the refrigerant.