Refrigerating and air-conditioning apparatus

Patent metadata

Field	Value
Publication number	US-9574816-B2
Application number	US-201013641885-A
Country	US
Kind code	B2
Filing date	May 26, 2010
Priority date	May 26, 2010
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A refrigeration cycle that is formed by connecting a compressor, a condenser, an expansion valve, and an evaporator and that performs cooling operation; an evaporator heating device that heats the evaporator; a drain pan that receives drain-water from the evaporator and drains the drain-water; a drain-pan heating device that heats the drain pan; a frost detecting device including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; and a control device that controls on-off operation of the evaporator heating device and the drain-pan heating device. The control device determines a frosting condition on the evaporator from an output of the frost detecting device and individually controls the evaporator heating device and the drain-pan heating device in accordance with the determination result.

First claim

The invention claimed is:

1. A refrigerating and air-conditioning apparatus comprising:
a refrigeration cycle being formed by connecting a compressor, a condenser, an expansion valve, and an evaporator, the refrigeration cycle performing a cooling operation;
an evaporator heating device heating the evaporator;
a drain pan receiving drain-water from the evaporator and draining the drain-water;
a drain-pan heating device heating the drain pan;
a frost detecting device including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light;
a control device controlling on-off operation of the evaporator heating device and the drain-pan heating device,
the control device, being configured to turn on the evaporator heating device based on the output of the frost detecting device, and then, calculate an inclination of an output voltage of the frost detecting device successively, determine that the frost formed on the evaporator has started to melt when the inclination is 1.5 times or more of an absolute value of an inclination of initial operation, and turn on the drain-pan heating device.

2. The refrigerating and air-conditioning apparatus of claim 1 , wherein based on the output of the frost detecting device, if the control device determines that the frosting condition on the evaporator has reached a frosting condition that is at a limit to allow a desired cooling capacity be maintained, the control device turns on the evaporator heating device and does not turn on the drain-pan heating device.

3. The refrigerating and air-conditioning apparatus of claim 2 , wherein if an output voltage V from the frost detecting device or a light intensity P calculated from the output voltage V is greater than or equal to a predetermined voltage Von or a predetermined light intensity Ps, the control device determines that the frosting condition on the evaporator has reached a frosting condition that is at a limit to allow a desired cooling capacity be maintained.

4. The refrigerating and air-conditioning apparatus of claim 1 , wherein if the control device determines that the frost is removed from the evaporator on the basis of an output of the frost detecting device after the evaporator heating device is turned on, the control device turns off the evaporator heating device.

5. The refrigerating and air-conditioning apparatus of claim 4 , wherein if an output voltage V from the frost detecting device or a light intensity P calculated from the output voltage V is smaller than or equal to a predetermined voltage Voff or a predetermined light intensity Po after the evaporator heating device is turned on, the control device determines that the frost is removed from the evaporator.

6. The refrigerating and air-conditioning apparatus of claim 4 , wherein if a state in which an inclination of an output voltage of the frost detecting device after the drain-pan heating device is turned on is smaller than or equal to a second inclination threshold value continues for a predetermined time, the control device determines that the frost is removed from the evaporator.

7. The refrigerating and air-conditioning apparatus of claim 1 , further comprising a drain-pan-temperature detector, wherein if the control device detects that a temperature detected by the drain-pan-temperature detector after the evaporator heating device is turned on has reached a minimum value, the control device determines that the frost is removed from the evaporator and turns off the evaporator heating device.

8. The refrigerating and air-conditioning apparatus of claim 1 , wherein when a predetermined water-draining time elapses after the evaporator heating device is turned off, the control device turns off the drain-pan heating device.

9. The refrigerating and air-conditioning apparatus of claim 1 ,
wherein the control device is configured to store a relationship between a time from start of a defrosting operation to start of melting of the frost and an amount of frost in advance and to estimate an amount of frost based on the relationship and a time measured during an actual operation from the start of the defrosting operation to the start of melting of the frost, and
wherein the control device is configured to store a relationship between an amount of frost and a draining time in advance, estimate an amount of water-draining time, on the basis of the relationship and the estimated amount of frost during the actual operation, and turn off the drain-pan heating device when the water-draining time elapses and the defrosting operation is terminated after the frost has started to melt.

10. The refrigerating and air-conditioning apparatus of claim 7 , wherein the control device estimates an amount of frost from an amount of time from after a detection value obtained by the drain-pan-temperature detector becomes maximum until the detection value reaches the minimum value, sets a water-draining time on the basis of the estimated amount of frost, and turns off the drain-pan heating device when the water-draining time elapses after the evaporator heating device is turned off.

11. The refrigerating and air-conditioning apparatus of claim 1 , wherein the drain-pan heating device utilizes a high-temperature high-pressure refrigerant discharged from the compressor.

12. The refrigerating and air-conditioning apparatus of claim 1 , wherein the frost detecting device is attached to the evaporator in a movable manner so as to be capable of detecting the frosting condition of the entire evaporator.

Assignees

• Hamada Mamoru
• Unezaki Fumitake
• Morikawa Akira
• Ueyama Satoshi
• Yamashita Koji
• Morimoto Hiroyuki
• Motomura Yuji
• Yamashita Tetsuya
• Otsubo Yusuke
• Mitsubishi Electric Corp

Inventors

• Hamada Mamoru
• Unezaki Fumitake
• Morikawa Akira
• Ueyama Satoshi
• Yamashita Koji
• Morimoto Hiroyuki
• Motomura Yuji
• Yamashita Tetsuya
• Otsubo Yusuke

Classifications

• F25B49/02

  for compression type machines, plants or systems · CPC title

• F25D2600/02

  Timing · CPC title

• F25D21/02

  Detecting the presence of frost or condensate · CPC title

• F25D21/14

  Collecting or removing condensed and defrost water; Drip trays · CPC title

• F24F11/42

  of outdoor units · CPC title