Refrigerant cycle device with ejector

Abstract

A refrigerant cycle device having an ejector includes a first evaporator for evaporating refrigerant flowing out of the ejector, a first passage portion for guiding refrigerant to a refrigerant suction port of the ejector, a throttle unit located in the first passage portion, a second evaporator located in the first passage portion downstream of the throttle unit, a bypass passage portion for guiding hot gas refrigerant from a compressor into the second evaporator, a bypass opening and closing unit provided in the bypass passage portion. Furthermore, a second passage portion is branched from the bypass passage portion downstream of the bypass opening and closing unit, and a flow control unit is provided in the second passage portion to prevent a flow of refrigerant from the first evaporator to the second evaporator through the second passage portion. Therefore, defrosting of both the first and second evaporators can be suitably performed.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Applications No. 2006-175803 filed on Jun. 26, 2006, and No. 2006-180240 filed on Jun. 29, 2006, the contents of which are incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates to a refrigerant cycle device having an ejector that functions as refrigerant decompressing means and refrigerant circulating means.BACKGROUND OF THE INVENTION[0003]JP-A-2006-118849 proposes a vapor-compression refrigerant cycle device. This vapor-compression refrigerant cycle device is so constructed that: an ejector is used as refrigerant decompressing means and refrigerant circulating means in a refrigeration cycle; and multiple evaporators (e.g., first evaporator, second evaporator) are located downstream of and on the refrigerant suction side of this ejector. The vapor-compression refrigerant cycle device is provided with: an ejector shutting mechanism that opens a...

AI Technical Summary

Benefits of technology

[0006]In consideration of the above problems, it is an object of the present invention to provide a refrigerant cycle device, which can effectively reduce a difference between defrosting operation of a first evaporator and defrosting operation of a second evaporator.

[0007]It is another object of the present invention to provide a refrigerant cycle device in which refrigerant temperatures of first and second evaporators can be made more even during a defrosting operation of the first and second evaporators.

[0008]It is further another object of the present invention to provide a refrigerant cycle device, which can shorten a defrosting time of an evaporator.

[0009]It is further another object of the present invention to provide a refrigerant cycle device, which can increase cool-down speed in a cooling operation after a defrosting operation.

[0011]Accordingly, when the bypass opening and closing unit is closed, the refrigerant discharged from the compressor passes through the radiator, and flows into the first evaporator through the ejector while a part of refrigerant flows into the second evaporator through the first passage portion. Therefore, in the refrigerant cycle device, the first and second evaporators have cooling capacity (refrigerating function) so that cooling mode can be performed. In the cooling mode of the refrigerant cycle device, the surfaces of the first and second evaporators may be frosted. In this case, the bypass opening and closing unit is opened so that defrosting of the first and second evaporators can be performed. When the bypass opening and closing unit is opened, the hot gas refrigerant discharged from the compressor flows into the bypass passage portion and the second passage portion branched from the bypass passage portion. Accordingly, it is possible to introduce the hot gas refrigerant directly into both the first evaporator and the second evaporator, thereby defrosting of the first and second evaporators can be performed. As a result, it is possible to effectively reduce a difference between defrosting operation of a first evaporator and defrosting operation of a second evaporator. Thus, refrigerant temperatures of the first and second evaporators can be made more even during the defrosting operation.

[0018]In this refrigerant cycle device, during a defrosting operation of the first and second evaporators, hot gas refrigerant discharged from the compressor can flow through the bypass passage portion to the second evaporator, to the ejector and to the first evaporator in this order. In this example of the present invention, because the flow resistance of refrigerant flowing in the second evaporator is greater than that of refrigerant flowing in the first evaporator, the pressure loss in the second evaporator can be made large, thereby increasing the mean temperature of refrigerant passing through the second evaporator during the defrosting operation. As a result, it is possible to shorten the defrosting time and increase cool-down speed in a cooling operation after the defrosting operation.

Problems solved by technology

However, the above technique involves a problem.

In this case, though defrosting is more effectively carried out at the second evaporator than at the first evaporator, the temperature is needlessly prone to rise at the second evaporator until the defrosting of the first evaporator is completed, thereby reducing cool-down speed in a cooling operation after the defrosting operation.

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