Vehicle air conditioner with defrosting operation of exterior heat exchanger

• US 6,725,679 B2
• Filed: 09/20/2001
• Issued: 04/27/2004
• Est. Priority Date: 09/27/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yamanaka, Yasushi, Itoh, Satoshi, Hirata, Toshio, Iritani, Kunio, Tomatsu, Yoshitaka, Honda, Keita, Yamaguchi, Motohiro
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US09/961,515
• Publication Number:
  US 20020036080A1
• Time in Patent Office: 950 Days
• Field of Search: 621/60, 621/51, 621/55, 621/56, 621/40, 62/82, 622/78, 622/77, 237/2.B, 165/231, 165/232, 165/233, 165/240, 165/241, 165/242
• US Class Current: 62/160
• CPC Class Codes: B60H 1/00392 for electric vehicles having only electric drive means
• CPC Class Codes: B60H 1/00907 where the flow direction of the refrigerant changes and an evaporator becomes condenser
• CPC Class Codes: B60H 1/3207 for minimizing the humidity of the air
• CPC Class Codes: B60H 2001/00935 comprising four way valves for controlling the fluid direction
• CPC Class Codes: B60H 2001/00961 comprising means for defrosting outside heat exchangers
• 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 2400/04 Refrigeration circuit bypassing means
• CPC Class Codes: F25B 2600/02 Compressor control
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 2700/21152 at the discharge side of the compressor
• CPC Class Codes: F25B 41/20 Disposition of valves, e.g. of on-off valves or flow control valves expansion valves F25B41/31
• CPC Class Codes: F25B 41/385 Dispositions with two or more expansion means arranged in parallel on a refrigerant line leading to the same evaporator
• CPC Class Codes: F25B 47/02 Defrosting cycles
• CPC Class Codes: F25B 47/025 by reversing the cycle

Abstract

In a vehicle air conditioner with a heat pump cycle having an interior heat exchanger and an exterior heat exchanger, when a frosting on a surface of the exterior heat exchanger is determined and when a temperature of hot water supplied to a heater core is equal to or higher than a predetermined temperature, the exterior heat exchanger is defrosted in a defrosting operation. Accordingly, the defrosting operation can be performed while a sufficient heating can be obtained.

Claims

1. An air conditioner for a vehicle having a passenger compartment, comprising:

a heater pump cycle including a compressor for compressing and discharging refrigerant, an interior heat exchanger for performing a heat exchange between refrigerant and air blown into the passenger compartment, and an exterior heat exchanger for performing a heat exchange between refrigerant and outside air outside the passenger compartment;

a heat core for heating air blown into the passenger compartment by performing a heat exchange between air and a fluid which recovers waste heat generated in the vehicle;

frosting determination means for determining whether a surface of the exterior heat exchanger is frosted;

heating capacity determining means for determining whether a heating capacity of the heater core is larger than a predetermined capacity; and

a control unit for controlling operation of the heat pump cycle, wherein;

at least when the frosting determination means determines a frosting on the surface of the exterior heat exchanger, and when the heating capacity determining means determines that the heating capacity of the heater core is larger than the predetermined capacity, the control unit performs a defrosting operation in which the surface of the exterior heat exchanger is defrosted.

2. The air conditioner according to claim 1, further comprising

a fluid temperature detecting unit for detecting a temperature of the fluid supplied to the heater core, wherein,

when the temperature of the fluid, detected by the fluid temperature detecting unit is higher than a predetermined temperature, the heating capacity determining means determines that the heating capacity of the heater core is larger than the predetermined capacity.

3. The air conditioner according to claim 1, further comprising

a vehicle speed detecting unit for detecting a vehicle speed, wherein,

the control unit performs the defrosting operation when the vehicle speed is higher than a predetermined speed.

4. The air conditioner according to claim 1, further comprising

a vehicle speed detecting unit for detecting a vehicle speed, wherein,

the control unit performs the defrosting operation when the vehicle speed is higher than a first predetermined speed and a lower than a second predetermined speed that is larger than the first predetermined speed.

5. The air conditioner according to claim 1, further comprising

air temperature adjusting means for adjusting temperature of air blown into the passenger compartment by adjusting a heating degree due to the heater core, wherein,

when the air temperature adjusting means adjusts the heating degree at the maximum degree, the heating capacity determining means determines that the heating capacity of the heater core is lower than the predetermined capacity.

6. The air conditioner according to claim 1, further comprising:

target air temperature calculating means for calculating a target temperature of air blown into the passenger compartment, wherein,

when the target temperature of air blown into the passenger compartment is lower than a predetermined temperature, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

7. The air conditioner according to claim 1, further comprising:

an outside air detecting unit for detecting temperature of outside air, wherein,

when the temperature of the outside air is higher than a predetermined temperature, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

8. The air conditioner according to claim 1, further comprising:

an inside air temperature detecting unit for detecting temperature of inside air inside the passenger compartment, wherein,

when the temperature of the inside air is higher than a predetermined temperature, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

9. The air conditioner according to claim 1, further comprising:

a vehicle speed detecting unit for detecting a vehicle speed, wherein,

when the vehicle speed is lower than a predetermined speed, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

10. The air conditioner according to claim 1, wherein the fluid supplied to the heater core is cooling water for cooling one of an engine and a fuel cell mounted on the vehicle.

11. The air conditioner according to claim 1, wherein the fluid supplied to the heater core is cooling water for cooling an engine of the vehicle, the air conditioner further comprising

a radiator for cooling the cooling water by performing a heat exchange between the cooling water and outside air, wherein,

when the cooling water is cooled in the radiator, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

12. The air conditioner according to claim 1, wherein the fluid supplied to the heater core is cooling water for cooling an engine mounted on the vehicle, the air conditioner further comprising

a rotation speed detecting unit for detecting a rotation speed of the engine, wherein,

when the rotation speed of the engine is higher than a predetermined speed, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

13. The air conditioner according to claim 1, wherein:

the fluid supplied to the heater core is cooling water for cooling an engine mounted on the vehicle;

when a passed time from a start of the engine is larger than a predetermined time, the heating capacity determining means determines that the heating capacity is larger than the predetermined capacity.

14. The air conditioner according to claim 1, wherein,

in the defrosting operation, the heat pump cycle is controlled to be operated in such a manner that heat of refrigerant is radiated in the exterior heat exchanger and is absorbed in the interior heat exchanger.

15. The air conditioner according to claim 1, wherein:

in a heating operation for heating the passenger compartment, the control unit controls the heat pump cycle in such a manner that refrigerant discharged from the compressor flows into the exterior heat exchanger after passing through the interior heat exchanger; and

in the defrosting operation, a part of refrigerant flowing from a discharge side of the compressor directly flows into the exterior heat exchanger while bypassing the interior heat exchanger.

16. The air conditioner according to claim 1, further comprising

a refrigerant heating unit in which the fluid is heat-exchanged with refrigerant to heat refrigerant,

wherein the defrosting operation is performed by heating refrigerant using the refrigerant heating unit.

17. The air conditioner according to claim 1, wherein the interior heat exchanger is disposed at an upstream air side of the heater core.

18. The air conditioner according to claim 1, wherein:

the heat pump cycle further includes a four-way switching valve for switching a refrigerant flow in the heat pump cycle; and

the four-way switching valve is disposed to switch one of a cooling operation where heat of refrigerant is radiated in the exterior heat exchanger and is absorbed in the interior heat exchanger, and a heating operation where heat of refrigerant is radiated in the interior heat exchanger and is absorbed in the exterior heat exchanger.

19. The air conditioner according to claim 1, wherein the compressor is an electrical compressor driven by electrically.

20. The air conditioner according to claim 1, further comprising:

a temperature detecting unit for detecting temperature of the fluid supplied into the heater core; and

an air temperature adjusting unit which adjusts a heating degree due to the heater core based on the temperature detected by the temperature detecting unit, to adjust temperature of air blown into the passenger compartment.