Patent Application
20060254308
This application is based on Japanese Patent Applications No. 2005-142476 filed on May 16, 2005, No. 2005-148470 filed on May 20, 2005, No. 2005-151588 filed on May 24, 2005, No. 2005-213272 filed on Jul. 22, 2005, and No. 2005-219354 filed on Jul. 28, 2005, the contents of which are incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an ejector cycle device having an ejector which has a function for reducing pressure of refrigerant and a function for circulating refrigerant.
2. Description of the Related Art
This kind of ejector cycle device has been known in JP-B1-3322263, for example. JP-B1-3322263 discloses an ejector cycle device that has a first evaporator and a second evaporator. The second evaporator is arranged on the downstream side of refrigerant flow of an ejector having functions for reducing pressure of refrigerant and for circulating refrigerant, a vapor—liquid separator is arranged on the downstream side of refrigerant flow of this second evaporator, and the first evaporator is interposed between a liquid refrigerant outlet of the vapor—liquid separator and a refrigerant suction port of the ejector.
According to this ejector cycle device, vapor-phase refrigerant discharged from the first evaporator is drawn by the use of a pressure drop caused by a high-speed flow of refrigerant when refrigerant is expanded and the velocity energy of refrigerant when refrigerant is expanded is converted to pressure energy by a diffuser portion (pressure increasing portion) to increase the pressure of refrigerant (suction pressure). Hence, it is possible to reduce the driving power of a compressor and hence to enhance the operation efficiency of a refrigerant cycle.
Moreover, it is possible to perform a heat absorption (cooling) operation in separate spaces by both of the first and second evaporators or in the same space by using the two evaporators. In an ejector cycle device having an evaporator (above-mentioned first evaporator) arranged only on the refrigerant suction port of the ejector, a mechanical or electrical control valve is arranged on the upstream side of the ejector or the upstream side of the evaporator.
The opening of the control valve arranged on the upstream side of the ejector is controlled so as to control the degree of superheat at the outlet of the evaporator or the high pressure of refrigerant in the refrigerant cycle. The opening of the control valve arranged on the upstream side of the evaporator is controlled to thereby control the degree of superheat of refrigerant at the outlet of the evaporator.
The control valve described in JP-B1-3322263 controls the degree of superheat at the outlet of the evaporator or the high pressure of refrigerant at the time of an ejector cycle device operation, but does not open and close a refrigerant passage in operative connection with the intermittent operation of the compressor. For this reason, even when the compressor is stopped, the control valve is kept in a state of a specified opening. Accordingly, when the compressor is stopped, a phenomenon in which the high pressure and low pressure of the cycle is brought into a uniform state, that is, a pressure balance is developed. In the process of developing this pressure balance, refrigerant passing through the nozzle portion of the ejector causes flowing noises. In particular, when the compressor is stopped, the compressor does not cause operation noise to produce silent environment and hence the flowing noises caused by the nozzle portion becomes offensive to the ear.
Moreover, when the compressor is stopped and then is started again, liquid refrigerant is returned to the compressor and is compressed by the compressor. In this case, the life of durability of the compressor is deteriorated.
For example, when an inside temperature of a space to be cooled is decreased to an extremely low temperature close to, for example, −20° C. like a vehicle-mounted refrigerator, the low pressure of the refrigerant cycle needs to be decreased to a low pressure corresponding to this extremely low temperature close to −20° C. Hence, the pressure difference between high pressure and low pressure of the refrigerant cycle when the compressor is stopped becomes very large.
Therefore, in the process of developing pressure balance when the compressor is stopped, a large amount of liquid refrigerant flows from the high-pressure side to the low-pressure side through the nozzle portion of the ejector. At this time, the inside temperature is already reduced to the extremely low temperature and the thermal load of the evaporator becomes small and refrigerant is not drawn to the suction side of the compressor. Hence, refrigerant flowing to the low pressure side collects as liquid-phase refrigerant in the vapor—liquid separator and the evaporator on the downstream side of the ejector. As a result, when the compressor is started next time, the liquid refrigerant may overflow from the vapor—liquid separator and may return to the compressor.
Moreover, JP-A-2005-308380 (corresponding to US 2005/0178150A1, US 2005/0268644A1) proposes an ejector cycle device having: a branch passage, which is branched from a branch point of a refrigerant passage on the upstream portion of an ejector and is connected to the refrigerant suction port of the ejector; a throttle mechanism and a first evaporator arranged in the branch passage; and a second evaporator arranged on the downstream side of refrigerant flow of the ejector. According to this ejector cycle device, the first evaporator is connected in parallel to the ejector, and the branch passage has the throttle mechanism exclusive to the first evaporator. In this case, the amounts of refrigerant of the first and second evaporators can be easily controlled. However, in the process of developing pressure balance when the compressor is stopped, refrigerant passing though the nozzle portion of the ejector and the throttle mechanism of the branch passage causes flowing noises.
Moreover, when an inside temperature of a space to be cooled is decreased to an extremely low temperature close to, for example, −20° C. like a vehicle-mounted refrigerator, the thermal load of the evaporator becomes small when the compressor is stopped. Hence, in the process of developing pressure balance, a phenomenon develops in which refrigerant flows into the first and second evaporators and collects there. In this case, when the refrigerant further flows into the liquid refrigerant staying in the first and second evaporators, the refrigerant flow causes flowing noises. Moreover, liquid refrigerant, collecting in the first and second evaporators while the compressor is stopped, is drawn by the compressor and the liquid refrigerant is returned into the compressor when the compressor is started next time.
Furthermore, as shown in JP-A-5-312421, there has been known an ejector cycle device constructed of: a refrigerant passage for connecting a compressor, a radiator, an ejector, and a first evaporator; and a branch passage branched from the refrigerant passage and including throttle means, and a second evaporator.
However, in the ejector cycle device described in JP-A-5-312421, frost easily adheres to three portions of the second evaporator that is comparatively low in evaporation temperature, an upwind portion of the first evaporator that is arranged on the upstream side of air flow because the first evaporator is comparatively high in evaporation temperature, and an accumulator (vapor—liquid separator) arranged on the downstream side of refrigerant flow of the first evaporator. When the frost deposits in the three portions, the cooling efficiency of the ejector cycle device is greatly deteriorated.
In view of the foregoing problems, it is an object of the present invention to provide an ejector cycle device which can prevent a refrigerant flowing noise when a compressor is stopped.
It is another object of the present invention to provide an ejector cycle device which can prevent liquid refrigerant, staying in an evaporator while a compressor is stopped, from being introduced into the compressor at the next operation time of the compressor.
It is further another object of the present invention to provide an ejector cycle device which can effectively remove frost on a low-pressure side component, e.g., evaporators and an accumulator.
According to an aspect of the present invention, an ejector cycle device includes: a compressor that draws and compresses refrigerant; a radiator that radiates heat of high-pressure refrigerant discharged from the compressor; an ejector disposed at a downstream side of the radiator to decompress and expand refrigerant from the radiator; an evaporator that is arranged in a refrigerant branch passage connected to a refrigerant suction port of the ejector; an opening/closing member that opens and closes a refrigerant flow and is capable of preventing refrigerant from flowing into the evaporator; and a control unit that brings the opening/closing member into a closing state in a time period for which the operation of the compressor is stopped. Accordingly, while the operation of the compressor is stopped, the opening/closing member prevents a refrigerant flow into the evaporator. Therefore, it can prevent liquid refrigerant from collecting in the evaporator while the compressor is stopped, and prevent liquid refrigerant from the evaporator from returning to the compressor when the compressor is restarted in the next time. As a result, when the operation of the compressor is stopped, a refrigerant flowing noise can be restricted.
For example, the evaporator connected to the refrigerant suction port is arranged as a first evaporator, and a second evaporator can be arranged on a downstream side of the ejector. In this case, the first evaporator and the second evaporator can be disposed to cool one space to be cooled, or can be disposed to cool separate spaces to be cooled.
Furthermore, a temperature detecting member for detecting temperature relating to a temperature of a space to be cooled of the evaporator can be disposed, and the control unit can intermittently control operation of the compressor on the basis of temperature detected by the temperature detecting member. The refrigerant branch passage can be branched at a branch point on an upstream side of the ejector and can be connected to the refrigerant suction port. Furthermore, the opening/closing member may be an opening/closing valve arranged on an upstream side of the branch point, or a three-way valve arranged at the branch point, or an opening/closing valve arranged on an upstream side of the evaporator in the refrigerant branch passage, or a passage opening/closing mechanism arranged in the ejector itself.
The control unit can control the opening/closing member from the closing state to an opening state in the time period for which the compressor is stopped, and then can restart the operation of the compressor. Furthermore, the control unit can control the opening/closing member from an opening state to a closing state before stopping the compressor and can continuously keep the compressor in an operating state for a specified time in a state where the opening/closing member is closed, and then stops the compressor.
Furthermore, the opening/closing member can include an opening/closing valve arranged on an upstream side of the evaporator connected to the refrigerant suction port, and a passage opening/closing mechanism arranged in the ejector itself. In this case, the control unit controls the opening/closing valve from a closing state to an opening state in the time period for which the compressor is stopped to thereby bring pressure in a refrigerant cycle into balance, and then returns the passage opening/closing mechanism into an opening state and then restarts the operation of the compressor.
In the ejector cycle device, a throttle mechanism can be arranged on an upstream side of the opening/closing member to reduce pressure of refrigerant on the upstream side of the opening/closing member in such a way as to bring the refrigerant into two phases of vapor and liquid. Furthermore, the ejector and the opening/closing valve can be combined with each other at least as one integrated unit.
According to another aspect of the present invention, an ejector cycle device includes a compressor that draws and compresses refrigerant; a radiator that radiates heat of high-pressure refrigerant discharged from the compressor; an ejector that includes a nozzle portion for reducing pressure of refrigerant on a downstream side of the radiator to expand the refrigerant and draws refrigerant by a jet flow of refrigerant from the nozzle portion; a first evaporator that evaporates refrigerant to be drawn into a refrigerant suction port of the ejector so as to have a cooling capacity; a second evaporator that evaporates refrigerant flowing out of the ejector so as to have a cooling capacity; a frost removing member that heats the first and second evaporators so as to perform a frost removing operation where frost adhering to the first and second evaporators is removed; an evaporator temperature detecting member that detects temperature of at least one of the first evaporator and the second evaporator; and a control unit that controls the frost removing member to heat the first and second evaporators and to perform the frost removing operation when temperature detected by the evaporator temperature detecting member reaches a predetermined temperature. Accordingly, the frost removing operation of the first and second evaporators can be suitably performed while I can prevent cooling efficiency of the first and second evaporators from being deteriorated.
For example, the evaporator temperature detecting member can be disposed to detect the temperature of the first evaporator. In this case, the control unit controls the frost removing member to perform the frost removing operation when temperature of the first evaporator detected by the evaporator temperature detecting member reaches a predetermined temperature. Alternatively, the evaporator temperature detecting member can be disposed to detect the temperature of the second evaporator. In this case, the control unit controls the frost removing member to perform the frost removing operation when temperature of the second evaporator detected by the evaporator temperature detecting member reaches a predetermined temperature.
Alternatively, an accumulator can be arranged on a downstream side of the second evaporator in a refrigerant flow, and an accumulator temperature detecting member can be disposed to detect a temperature of the accumulator. Furthermore, the evaporator temperature detecting member can be provided with a first evaporator temperature sensor disposed to detect a temperature of the first evaporator, and a second evaporator temperature sensor disposed to detect the temperature of the second evaporator. In this case, the control unit controls the frost removing member to perform the frost removing operation when a temperature detected by any one of the accumulator temperature detecting member and the first and second evaporator temperature sensors reaches a predetermined temperature or more.
The control unit can perform the frost removing operation of the first and second evaporators in a state where the compressor is stopped.
The frost removing member can be provided with a passage switching means arranged on a downstream side of refrigerant flow of the radiator, and a hot-gas supply passage through which high-temperature refrigerant from the passage switching means is supplied to an upstream side of the refrigerant flow of the second evaporator. In this case, the control unit controls the passage switching means to switch a refrigerant passage to the hot-gas supply passage in a state where the compressor is operated, and performs the frost removing operation of the first and second evaporators by using the high-temperature refrigerant.
According to further another aspect of the present invention, an ejector cycle device includes a compressor that draws and compresses refrigerant, a radiator that radiates heat of high-pressure refrigerant discharged from the compressor, an ejector that includes a nozzle portion for reducing pressure of refrigerant on a downstream side of the radiator to expand the refrigerant and draws refrigerant by a jet flow of refrigerant from the nozzle portion, a first evaporator that evaporates refrigerant to be drawn into a refrigerant suction port of the ejector to have a cooling capacity, a second evaporator that evaporates refrigerant flowing out of the ejector to have a cooling capacity, an accumulator that is arranged on a downstream side of the second evaporator in a refrigerant flow, a frost removing member that heats the first and second evaporators so as to perform a frost removing operation where frost adhering to the first and second evaporators is removed, an accumulator temperature detecting member that detects a temperature of the accumulator, and a control unit that controls the frost removing member to heat the first and second evaporators and to perform the frost removing operation when temperature of an outer wall of the accumulator detected by the accumulator temperature detecting member reaches a predetermined temperature. Even in this case, it can effectively restrict a component on a low refrigerant pressure side, such as the accumulator from being frosted.
Even in this case, the frost removing member can be arranged on an upstream air side of the first and second evaporators.
According to another aspect of the present invention, a frost removing member can be disposed to heat the first and second evaporators so as to perform a frost removing operation where frost adhering to the first and second evaporators is removed, and a control unit can control the frost removing member to perform the frost removing operation of the first and second evaporators. Therefore, it is possible to suitable perform the frost removing operation while effectively performing the cooling operation of the first and second evaporators.
For example, the frost removing member can be constructed with a plurality of heater portions for heating the first and second evaporators in the frost removing operation. Furthermore, the frost removing member can be located at an upstream air side of each of first and second evaporators, or can be located to contact both the first and second evaporators, or can be located to heat both the first and second evaporators.
Alternatively, the frost removing member can be provided at one side of the first and second evaporators. In this case, a radiant heat absorbing member can be provided at the other one of the first and second evaporators such that radiant heat from the frost removing member is delivered to the radiant heat absorbing member. Alternatively, the frost removing member is provided at one side of the first and second evaporators such that heat from the frost removing member is delivered to the other one of the first and second evaporators by convection.
According to further another aspect of the present invention, in an ejector cycle device, a heat conductive member can be disposed to connect the first evaporator and the second evaporator so as to transfer heat between the first evaporator and the second evaporator. In this case, by performing the frost removing operation, frost on the first and second evaporators can be effectively removed in a short time.
For example, the heat conductive member can be disposed to contact the frost removing member, or can be heat exchange fins disposed in the first and second evaporators, or a holding member for holding the first and second evaporators, or a side plates attached to side ends of the first and second evaporators.
Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings.
In the ejector cycle device 10 of this embodiment, a compressor 11 for sucking and compressing refrigerant is rotated and driven by a vehicle driving engine (not shown) via an electromagnetic clutch 12, a belt, and the like. This compressor 11 is connected to and disconnected from the vehicle driving engine by intermittently passing current through the electromagnetic clutch 12, thereby being intermittently operated. That is, the refrigerant discharge capacity of the compressor 11 is controlled by changing the rate of intermittent operation of the compressor 11 by intermittently operating the electromagnetic clutch 12.
A radiator 13 is arranged on the refrigerant discharge side of this compressor 11. The radiator 13 exchanges heat between high-pressure refrigerant discharged from the compressor 11 and outside air (air outside the vehicle compartment) sent by a cooling fan (not shown) to cool the high-pressure refrigerant.
In this embodiment, a usual chlorofluorocarbon-based refrigerant is used as refrigerant circulating in a refrigerant cycle. In this case, the ejector cycle device 10 constructs a subcritical-pressure cycle in which high pressure does not exceed the critical pressure of the refrigerant. Hence, the radiator 13 operates as a condenser for cooling and condensing refrigerant.
A liquid receiver 14 is arranged as a vapor—liquid separator for separating the vapor and liquid of refrigerant and for storing liquid refrigerant on the downstream of refrigerant flow of the radiator 13, and liquid refrigerant is discharged from this liquid receiver 14 to the downstream side. A throttle mechanism 15 is connected to the downstream side of refrigerant flow of the liquid receiver 14.
Specifically, this throttle mechanism 15 is constructed of a fixed throttle such as a capillary tube and an orifice and reduces high-pressure liquid refrigerant from the liquid receiver 14 to middle-pressure refrigerant in the state of two phases of vapor and liquid. Then, an opening/closing valve 16 is connected to the downstream side of this throttle mechanism 15. Specifically, this opening/closing valve 16 is constructed of an electromagnetic valve and is opened and closed in operative connection with the intermittent operation of the compressor 11 as will be described below.
Then, an ejector 17 is arranged on the more downstream side of the opening/closing valve 16. This ejector 17 is used as a pressure reducing means for reducing the pressure of refrigerant and also a refrigerant circulating means (momentum transport type pump) for circulating refrigerant by the suction operation (entangling action) of refrigerant flow jetting at high speeds.
The ejector 17 is provided with: a nozzle portion 17a that reduces the area of a passage, through which middle-pressure refrigerant having passed through the opening/closing valve 16 flows, and reduces the pressure of the middle-pressure refrigerant to thereby expand the middle-pressure refrigerant in an isentropic manner; and a refrigerant suction port 17b that is arranged in the same space as the refrigerant jetting port of the nozzle portion 17a and draws vapor-phase refrigerant from a first evaporator 18 to be described later.
A mixing portion 17c for mixing high-speed refrigerant from the nozzle portion 17a and refrigerant drawn from the refrigerant suction port 17b is arranged on the downstream side of the nozzle portion 17a and the refrigerant suction port 17b. Then, a diffuser portion 17d forming a pressure increasing part is arranged on the downstream side of the mixing portion 17c in the ejector 17.
This diffuser portion 17d is formed in a shape gradually increasing the area of passage of refrigerant and performs an action of reducing the speed of refrigerant flow and of increasing the pressure of refrigerant, that is, an action of converting the velocity energy of refrigerant to the pressure energy thereof.
Further, the ejector 17 is provided with a passage opening/closing mechanism 17e for variably controlling the area of passage of the nozzle portion 17a.
The base portion of the needle 17f is connected to a driving portion 17g and the needle 17f is moved in the direction of length of the passage (in the up and down direction in
When the needle 17f is moved down from the position in
A second evaporator 21 is connected to the downstream side of the diffuser portion 17d of the ejector 17 and the downstream side of refrigerant flow of this second evaporator 21 is connected to the suction side of the compressor 11.
Meanwhile, a refrigerant branch passage 19 is branched from the upstream part of the ejector 17 and the downstream side of this refrigerant branch passage 19 is connected to the refrigerant suction portion 17b of the ejector 17. A reference symbol Z denotes the branch point of the refrigerant branch passage 19.
A throttle mechanism 20 is arranged in this refrigerant branch passage 19, and the first evaporator 18 is arranged on the downstream side of this throttle mechanism 20. The throttle mechanism 20 is a pressure reducing unit for controlling the flow rate of refrigerant to the first evaporator 18 and, for example, can be constructed of a fixed throttle such as a capillary tube and an orifice. In this regard, an electric control valve having its valve opening (opening of throttle passage) controlled by an electrically-driven actuator may be used as the throttle mechanism 20.
In this embodiment, both the first and second evaporators 18, 21 are combined with each other to form an integrated structure. For example, the constituent parts of the two evaporators 18, 21 may be formed of aluminum and are bonded by brazing into the integrated structure.
Air to be cooled is blown by a common electrically driven blower 22 to the two evaporators 18, 21 as shown by arrow A in
Here, among these two evaporators 18, 21, the second evaporator 21 connected to a passage on the downstream side of the ejector 17 is arranged on the upstream side in the direction of flow of air, shown by arrow A, and the first evaporator 18 connected to the refrigerant suction port 17b of the ejector 17 is arranged on the downstream side in the direction of flow of air, shown by arrow A.
In this regard, in this embodiment, the ejector cycle device 10 is used for the refrigerating device for a vehicle as described above and hence the common space 23 to be cooled is an inside space of a refrigerating unit for receiving goods to be refrigerated. In the space 23 to be cooled, a temperature sensor (thermistor) 24 for detecting an inside temperature of the space 23 is arranged.
Next, an electric control unit of this embodiment will be described on the basis of
Not only the detection value of the above-mentioned temperature sensor 24 but also detection signals from a group of sensors 26 and various kinds of operation signals from the operation panel 27 are inputted to the control unit 25.
Specifically, the group of sensors 26 include an outside air sensor for detecting an outside air temperature (temperature outside the vehicle compartment) and the like. The operation panel 27 is provided with a temperature setting switch for setting the cooling temperature of the space 23 to be cooled.
Next, the operation of the ejector cycle device 10 of the 1st embodiment will be described. First, there will be described a basic operation in the state of operation of the compressor 11. When current is passed through the electromagnetic clutch 12 by the control output of the control unit 25 to bring the electromagnetic clutch 12 into the state of connection, the rotational power of the vehicle engine is transmitted to the compressor 11 to operate the compressor 11.
In this state of operation of the compressor 11, the opening/closing valve 16 is brought into a valve opening state by the control output of the control unit 25. In the ejector 17, the driving portion 17g is driven by the control output of the control unit 25 to move the needle 17f to a specified opening position of the nozzle portion 17a.
Hence, refrigerant in a high-temperature high-pressure state, which is compressed by and discharged from the compressor 11, flows into the radiator 13. In the radiator 13, the high-temperature refrigerant is cooled and condensed by the outside air. The refrigerant after passing through the radiator 13 is separated into vapor and liquid by the liquid receiver 14 and the high-pressure liquid refrigerant is discharged to the downstream side of the liquid receiver 14 and is passed through the throttle mechanism 15.
The high-pressure liquid refrigerant is decompressed in the opening/closing valve 16 to a middle pressure, thereby being brought into a two-phase state of vapor and liquid phases. This middle-pressure refrigerant is branched at the branch point Z into a refrigerant flow toward the ejector 17 and a refrigerant flow toward the refrigerant branch passage 19.
The refrigerant flowing into the ejector 17 is reduced in pressure and is expanded by the nozzle portion 17a. Hence, the pressure energy of the refrigerant is converted into velocity energy by the nozzle portion 17a and the refrigerant is jetted out at a high speed from the jet port of this nozzle portion 17a. The refrigerant (vapor-phase refrigerant) after passing through the first evaporator 18 of the refrigerant branch passage 19 is drawn from the refrigerant suction port 17b by a reduction in pressure of the refrigerant at this time.
The refrigerant jetted from the nozzle portion 17a and the refrigerant drawn into the refrigerant suction port 17b mix with each other in the mixing potion 17c on the downstream side of the nozzle portion 17a and flows into the diffuser portion 17d. In this diffuser portion 17d, the area of passage is increased to convert the velocity energy (expansion energy) of refrigerant to pressure energy, thereby the pressure of refrigerant is increased.
The refrigerant flowing out of the diffuser portion 17d of the ejector 17 flows into the second evaporator 21. In the second evaporator 21, the low-pressure refrigerant at low temperature absorbs heat from the air blown in the direction shown by arrow A and evaporates. The vapor-phase refrigerant after evaporation is drawn into the compressor 11 and is again compressed.
In contrast, the refrigerant flowing into the refrigerant branch passage 19 has its pressure reduced by the throttle mechanism 20 and becomes low-pressure refrigerant, and the low-pressure refrigerant flows into the first evaporator 18. In the first evaporator 18, the refrigerant absorbs heat from air blown in the direction shown by arrow A and evaporates. The vapor-phase refrigerant after evaporation is drawn into the ejector 17 through the refrigerant suction port 17b.
As described above, according to this embodiment, the refrigerant on the downstream side of the diffuser portion 17d of the ejector 17 can be supplied to the second evaporator 21 and the refrigerant on the refrigerant branch passage 19 side can be supplied to the first evaporator 18 through the throttle mechanism 20. Hence, the first and second evaporators 18, 21 can perform a cooling operation at the same time. For this reason, the cool air cooled by both of the first and second evaporators 18, 21 is blown off into the space 23 to be cooled to cool the space 23.
At this time, the refrigerant evaporation pressure of the second evaporator 21 becomes pressure increased by the diffuser portion 17d, whereas the outlet of the first evaporator 18 is connected to the refrigerant suction port 17b of the ejector 17. Accordingly, the lowest pressure, which is produced immediately after the nozzle portion 17a, can be applied to the first evaporator 18.
With this, the refrigerant evaporation pressure (refrigerant evaporation temperature) of the first evaporator 18 can be lower than the refrigerant evaporation pressure (refrigerant evaporation temperature) of the second evaporator 21. The second evaporator 21 having a higher refrigerant evaporation temperature is arranged on the upstream side in the direction of flow of air shown by arrow A and the first evaporator 18 having a lower refrigerant evaporation temperature is arranged on the downstream side. Hence, both of a temperature difference between the refrigerant evaporation temperature and air temperature in the second evaporator 21 and a temperature difference between the refrigerant evaporation temperature and air temperature in the first evaporator 18 can be secured.
For this reason, the first and second evaporators 18, 21 can effectively improve their cooling capacities. Hence, the cooling capacity for the common space 23 to be cooled can be effectively increased by a combination of the first and second evaporators 18, 21. Moreover, the suction pressure of the compressor 11 can be increased by the diffuser portion 17d so as to decrease the driving power of the compressor 11.
Moreover, in the ejector cycle device of this embodiment, the refrigerant branch passage 19 branched from the branch point Z on the upstream side of the ejector 17 is connected to the refrigerant suction port 17b of the ejector 17, and is provided with the throttle mechanism 20 and the first evaporator 18. Hence, the low-pressure refrigerant of two phases of vapor and liquid can be independently supplied to the first evaporator 18 through the refrigerant branch passage 19.
For this reason, the flow rate of refrigerant flowing into the first evaporator 18 can be independently controlled by the throttle mechanism 20 without depending on the function of the ejector 17.
Moreover, under condition that cycle thermal load is small, the difference between high pressure and low pressure in the cycle becomes small, and therefore, a refrigerant amount flowing input to the ejector 17 becomes small. In this case, in the conventional cycle of JP-B1-3322263, the flow rate of refrigerant passing through the evaporator on the ejector suction side (corresponding to the first evaporator 18 in this embodiment) depends only on the refrigerant suction capacity of the ejector. Hence, an input refrigerant amount to the ejector decreases→the refrigerant suction capacity of the ejector decreases→the flow rate of refrigerant of suction-side evaporator decreases. This makes it difficult to secure the cooling capacity of the suction-side evaporator.
In contrast to this, according to this embodiment, the refrigerant flow is branched on the upstream side of the ejector 17 and this branched refrigerant is drawn into the refrigerant suction port 17b through the refrigerant branch passage 19. Hence, the refrigerant branch passage 19 is connected in parallel with the ejector 17 in the refrigerant cycle device 10.
For this reason, the refrigerant branch passage 19 can be supplied with the refrigerant by using not only the refrigerant suction capacity of the ejector 17 but also the refrigerant suction/discharge capacity of the compressor 11. With this, even when a phenomenon that the input of the ejector 17 decreases, the degree of a decrease in the flow rate of refrigerant of the first evaporator 18 can be made smaller. Hence, even under the conditions of low thermal load, the cooling capacity of the first evaporator 18 can be easily secured.
Next, the intermittent control of the compressor 11 will be described. Basically, the operation of the compressor 11 is intermittently controlled on the basis of such inside temperature Tr of the space 23 to be cooled (hereinafter, referred to “inside temperature”) that is detected by the temperature sensor 24.
Specifically, as shown in
Here, the lower limit set temperature Toff is, for example, approximately from −20° C. to −22° C., and the upper limit set temperature Ton is a predetermined temperature higher than the lower limit set temperature Toff, for example, approximately from −16° C. to −18° C.
In this manner, by intermittently controlling the operation of the compressor 11 according to the level of the inside temperature Tr, the inside temperature Tr is controlled to within a predetermined temperature range between the lower limit set temperature Toff and the upper limit set temperature Ton.
The opening/closing valve 16 and the passage opening/closing mechanism 17e of the ejector 17 are controlled by the control unit 25 in operatively connection with the intermittent control of the compressor 11 as follows. That is, when the inside temperature Tr decreases to the lower limit set temperature Toff, both of the opening/closing valve 16 and the passage opening/closing mechanism 17e of the ejector 17 are brought to a closing state in operative connection with the stopping of operation of the compressor 11.
The opening/closing valve 16 is continuously kept in a closing state for a first specified time t1 in a period during which the compressor 11 is stopped and then, first, is returned to an opening state. When the opening/closing valve 16 is returned to the opening state and then a second specified time t2 passes, the passage opening/closing mechanism 17e of the ejector 17 is returned to an opening state.
After the passage opening/closing mechanism 17e is returned to the opening state, the compressor 11 is again started. Here, the first specified time t1 and the second specified time t2 are set in such a way that t1>t2.
Specifically, either a first control based on the inside temperature Tr or a second control based on a timer function may be used for the control of opening and closing the opening/closing valve 16 and the passage opening/closing mechanism 17e of the ejector 17.
First, the first control will be now described. In the first control, as shown in
When the compressor 11 is stopped and then the inside temperature Tr increases to the first auxiliary set temperature T1, first, the opening/closing valve 16 is returned to an opening state. When the inside temperature Tr further increases to the second auxiliary set temperature T2, the passage opening/closing mechanism 17e of the ejector 17 is also returned to an opening state. Then, when the inside temperature Tr still further increases to the upper limit set temperature Ton, the compressor 11 is started again.
In contrast to this, the second control, the above-mentioned first specified time t1 and the second specified time t2 are directly set by the timer function of the control unit 25.
By bringing the opening/closing valve 16 into a closing state in operative connection with the operation of stopping the compressor 11 as described above, the passage on the upstream side of the branch point Z is brought into a shut state. With this, when the compressor 11 is stopped, it is possible to prevent the refrigerant on the upstream side of the opening/closing valve 16 from being flowed into the passage to the ejector 17 and into the refrigerant branch passage 19 by the difference between high pressure and low pressure in the cycle.
For this reason, when the compressor 11 is stopped, it is possible to prevent the occurrence of flowing noises when the refrigerant passes through the nozzle portion 17a of the ejector 17 and the throttle mechanism 20 of the branch passage 19.
At the same time, it is possible to prevent liquid refrigerant from collecting in the first and second evaporators 18, 21 and hence to prevent the liquid refrigerant from being returned to and compressed by the compressor 11 when the compressor is started next time.
Moreover, it is possible to prevent the refrigerant on the upstream side of the opening/closing valve 16 from flowing into the first and second evaporators 18, 21 for the first specified time t1 during which the opening/closing valve 16 is in a closing state. Hence, this can prevent high pressure and low pressure in the cycle from being brought into balance.
Specifically, as shown by solid lines H and L in the lower part in
This means that refrigerant temperatures in the first and second evaporators 18, 21 are kept at comparative low values also after the compressor 11 is stopped.
When the refrigerant flows into the first and second evaporators 18, 21 from the high pressure side when the compressor 11 is stopped, low pressure increases→refrigerant temperature in the first and second evaporators 18, 21 increases, and the inside temperature Tr increases. The increase in the inside temperature Tr results in causing a trouble of shortening the downtime of the compressor→increasing power required to drive the compressor. According to this embodiment, when the compressor 11 is stopped, the above-mentioned trouble can be avoided by bringing the opening/closing valve 16 into a closing state.
When the compressor 11 is stopped, the first and second evaporators 18, 21 are brought to a state where they substantially stop the cooling operation. Hence, in this embodiment, the electrically driven blower 22 for blowing air to the first and second evaporators 18, 21 are stopped in operative connection with the operation of stopping the compressor 11. However, when it is necessary to make a temperature distribution in the space 23 to be cooled uniform, the electrically driven blower 22 may be continuously operated also when the compressor 11 is stopped.
Moreover, when the opening/closing valve 16 is closed in operative connection with the operation of stopping the compressor 11 to suddenly interrupt the flow of non-compressive liquid-phase refrigerant, the refrigerant pressure on the upstream side of the opening/closing valve 16 may be abruptly increased to cause a water hammering phenomenon and to produce abnormal noises. However, in this embodiment, the throttle mechanism 15 is arranged on the upstream side of the opening/closing valve 16 and the flow of the middle-pressure refrigerant, which is reduced in pressure by this throttle mechanism 15 and is brought into the state of two phases of vapor and liquid, is interrupted by the opening/closing valve 16. Hence, the opening/closing valve 16 eventually interrupts the flow of refrigerant including compressive vapor-phase refrigerant.
As a result, this can prevent refrigerant pressure on the upstream side of the opening/closing valve 16 from increasing suddenly when the opening/closing valve 16 is closed. Hence, it is possible to avoid a water hammering phenomenon (liquid hammering phenomenon) and to prevent the occurrence of abnormal noises caused by the phenomenon.
The opening/closing valve 16 is kept in a closing state for the first specified time t1 and then is returned to an opening state. At this time, the passage opening/closing mechanism 17e of the ejector 17 is still kept in the closing state. Hence, the refrigerant passing through the opening/closing valve 16 passes through only the refrigerant branch passage 19 and flows through the first evaporator 18→the ejector 17→the second evaporator 21.
This can make high pressure and low pressure in the cycle uniform, that is, can bring high pressure and low pressure into balance. Specifically, when the opening/closing valve 16 is opened, high-pressure refrigerant flows into a low-pressure passage, thereby high pressure decreases to a still lower value when the opening/closing valve 16 is closed as shown by the solid line H in the lower part in
The high pressure and the low pressure in the cycle are brought into balance between the time when opening/closing valve 16 is opened and the time when the compressor 11 is again started (for the time t3). This time t3 becomes the period for a pressure balance. The broken lines b, c of the high pressure and the low pressure in the lower part in
In this embodiment, the high pressure and the low pressure in the cycle are brought into balance only for a period t3 of the latter half part during a period for which the compressor 11 is stopped. Hence, pressure balance is finished before the high pressure and the low pressure are brought to the same intermediate pressure. As a result, even when the pressure balance is finished (when the compressor 11 is again started), a pressure difference exists between the high pressure and the low pressure, as shown in
However, the pressure difference between the high pressure and the low pressure can be decreased by bringing the high pressure and the low pressure in the cycle into balance. Accordingly, power required to start the compressor 11 can be decreased by a large amount as compared with a case where the compressor 11 is started again while a large pressure difference is kept between the high pressure and the low pressure.
Moreover, the passage opening/closing mechanism 17e of the ejector 17 is kept in the closing state for a period t2 that is a large portion of this pressure balance period t3. Hence, it is possible to prevent the refrigerant from making flowing noises at the nozzle portion 17a of the ejector 17.
In
In
By the way, describing a preferable specific example in a case where the time period during which the opening/closing valve 16 is in a closing state (first specified time t1) is set in the manner shown by the second control by the timer function of the control unit 25, there is a correlation that the smaller the cycle thermal load, the smaller the degree of increase in the inside temperature for a period during which the compressor 11 is stopped and the longer the period during which the compressor 11 is stopped.
As shown in
There is a relationship of A>B>C among the valve closing times A, B and C, and the time t1 during which the opening/closing valve 16 is in a closing state is made longer as the outside air temperature becomes lower (that is, the thermal load in the cycle decreases). With this, the time t1 during which the opening/closing valve 16 is in a closing state can be determined to be an appropriate time corresponding to thermal load condition.
In
In the 1st embodiment, the opening/closing valve 16 is closed in operative connection with the operation of stopping the compressor 11. However, in the 2nd embodiment, as shown in
Here, the specified time t4 is a period of a pump-down operation in which the compressor 11 draws refrigerant on the low pressure side of the cycle and moves the refrigerant to high pressure side and holds the refrigerant on the high pressure side. By performing this pump-down operation, the amount of refrigerant collected in the first and second evaporators 18, 21 when the compressor 11 is stopped can be further reduced as compared with the 1st embodiment. Hence, it is possible to more effectively prevent a danger that the liquid refrigerant is returned to the compressor 11 and is compressed when the compressor 11 is again started next time.
For example, it is preferable that the pump downtime t4 is determined specifically according to the outside air temperature as shown in
There is a relationship of G>H>I among the pump downtimes G, H, and I, and the pump downtime t4 is determined to become longer as the outside air temperature Tam becomes lower (that is, the thermal load in the cycle decreases). With this, the pump downtime t4 can be determined to be an appropriate time corresponding to thermal load condition.
In the 1st embodiment, the throttle mechanism 15 and the opening/closing valve 16 are arranged on the upstream side of the branch point Z on the upstream side of the ejector 17. However, in the 3rd embodiment, as shown in
Hence, according to the 3rd embodiment, the opening/closing valve 16 shuts only the passage of the refrigerant branch passage 19. Hence, in the 3rd embodiment, both of the opening/closing valve 16 and the passage opening/closing mechanism 17e of the ejector 17 are brought into a closing state at the same time in operative connection with the operation of stopping the compressor 11. With this, the passage of the ejector 17 can be shut by the passage opening/closing mechanism 17e of the ejector 17 when the compressor 11 is stopped.
A 4th embodiment is a combination of the above-mentioned 3rd embodiment (cycle construction in
With this, the upstream portion of the first evaporator 18 of the refrigerant branch passage 19 can be shut and the inlet of the ejector 17 can be shut. The compressor 11 is continuously operated for the specified time t4 with the passage held shut, and then is stopped after this specified time t4 passes.
Hence, the compressor 11 performs a pump-down operation of sucking refrigerant on the low pressure side of the cycle and moving the refrigerant to the high pressure side for the specified time t4. With this, it is possible to more effectively decrease the amount of refrigerant collected in the first and second evaporators 18, 21 for the period during which the compressor 11 is stopped.
Also in the 4th embodiment, the time t4 of pump-down operation may be set to become longer as the outside air temperature Tam becomes lower (that is, the thermal load in the cycle decreases) as shown in
Specifically, this passage switching mechanism 30 is constructed of three-way solenoid valve and switches between a first state where the downstream portion of the first evaporator 18 is directly connected to the downstream side of the second evaporator 21 (suction side of the compressor 11) and a second state where the downstream portion of the first evaporator 18 is connected to the refrigerant suction port 17.
In the 1st embodiment, the first and second evaporators 18, 21 are integrated with each other and air is blown to the first and second evaporators 18, 21 by the blower 22 that is common to the first and second evaporators 18, 21, thereby cooling the common space 23 to be cooled by the first and second evaporators 18, 21. However, the 5th embodiment is different also in this point from the 1st embodiment.
That is, in the 5th embodiment, the first and second evaporators 18, 21 are constructed of separate bodies and are arranged in separate spaces 23a, 23b to be cooled. For this reason, air is blown to the first and second evaporators 18, 21 by separate blowers 22a, 22b, thereby cooling the separate spaces 23a, 23b with different temperatures.
Here, because the refrigerant evaporation temperature of the first evaporator 18 is lower than that of the second evaporator 21, the inside temperature of the first space 23a to be cooled by the first evaporator 18 is lower than the inside temperature of the second space 23b to be cooled by the second evaporator 21. For this reason, the second space 23b to be cooled is used, for example, as a cooling chamber in a refrigerator and the first space 23a to be cooled is used, for example, as a refrigerating chamber of the refrigerator.
Temperature sensors 24a, 24b for detecting inside temperatures Tr1, Tr2 are arranged in the two spaces 23a, 23b to be cooled. The detection signals of these two temperature sensors 24a, 24b are inputted to the control unit 25 (
When the second inside temperature Tr2 decreases to the lower limit set temperature Toff2 at a time t10, the control unit 25 switches the passage switching mechanism 30 from the second state to the first state. Hence, the downstream portion of the first evaporator 18 is directly connected to the downstream side (suction side of the compressor 11) of the second evaporator 21. At the same time, the control unit 25 brings the passage switching mechanism 17e of the ejector 17 into a closing state. Hence, refrigerant flow passing through the ejector 17 is interrupted and refrigerant flow into the second evaporator 21 is prevented.
With this, the cooling operation of the second evaporator 21 is stopped and hence the inside temperature Tr2 of the second space 23b to be cooled starts to increase. In contrast, refrigerant continuously flows through the first evaporator 18 and hence the inside temperature Tr1 of the first space 23a to be cooled decreases further also after the time t10.
When the inside temperature Tr1 of the first space 23a to be cooled decreases to the lower limit set temperature Toff1 at time t11, the control unit 25 brings the compressor 11 into a stopping state and at the same time brings the opening/closing valve 16 into a closing state. This closing state of the opening/closing valve 16 is continued for the time t1, thereby the refrigerant is prevented from flowing into the first evaporator 18 and the second evaporator 21. Hence, the inside temperature Tr1 of the first space 23a to be cooled starts to increase from the time t11.
Then, after the time t1 passes, the opening/closing valve 16 returns to the opening state. At this time, because the compressor 11 is continuously held stopped, when the opening/closing valve 16 is opened, the high pressure and low pressure of the cycle are changed in the direction of making pressures uniform, thereby being brought into balance. The high pressure and low pressure of the cycle are brought into balance for the time t3 until the compressor 11 is again started. In contrast, after the opening/closing valve 16 returns to the opening state and then the time t2 passes, the passage opening/closing mechanism 17e of the ejector 17 returns to the opening state (time t2<time t3).
When the inside temperature Tr2 of the second space 23b to be cooled increases to the upper limit set temperature Ton2 at a time t12, the control unit 25 starts the compressor 11 again and switches the passage switching mechanism 30 from the first state to the second state. Hence, the downstream portion of the first evaporator 18 is connected to the refrigerant suction port 17b of the ejector 17.
Thereafter, the above-mentioned operation is repeatedly performed, thereby the inside temperature Tr1 of the first space 23a to be cooled and the inside temperature Tr2 of the second space 23b to be cooled can be controlled to within a predetermined temperature range between their lower limit set temperatures Toff1, Toff2 and the upper limit set temperatures Ton1, Ton2. At the same time, the operation and effect of preventing the liquid refrigerant from collecting in the first and second evaporators 18, 21 when the compressor 11 is stopped can be exerted similarly to the 1st embodiment.
By the way, in the above-mentioned description of operation has been provided a description to the effect that the compressor 11 is stopped when the inside temperature Tr1 of the first space 23a to be cooled decreases to the lower limit set temperature Toff1. More specifically, when an AND condition (predetermined condition) that the inside temperature Tr1 of the first space 23a to be cooled (one space to be cooled) decreases to the lower limit set temperature Toff1 and that the inside temperature Tr2 of the second space 23b to be cooled (other space to be cooled) does not increase to the upper limit set temperature Ton2 is satisfied, the compressor 11 is stopped. This is because it is possible to determine a state where the cooling actions of both of the first and second evaporators 18, 21 can be stopped by the satisfaction of this AND condition.
That is, when the inside temperature of either of these two spaces 23a, 23b to be cooled decreases to the lower limit set temperature and the inside temperature of the other space does not increase to the upper limit set temperature, it is only necessary to stop the compressor 11.
Moreover,
The bottom line is that the compressor 11 is continuously held stopped before both of the inside temperature Tr1 of the first space 23a to be cooled and the inside temperature Tr2 of the second space 23b to be cooled do not increase to the upper limit set temperatures Ton1, Ton2 and that it is only necessary to start the compressor 11 again when either of the inside temperature Tr1 of the first space 23a to be cooled or the inside temperature Tr2 of the second space 23b to be cooled increases to either of the upper limit set temperatures Ton1, Ton2.
In this regard, it is only necessary to operate the blowers 22a, 22b of the first and second spaces 23a, 23b to be cooled in operative connection with the intermittent flow of refrigerant into the corresponding evaporators 18, 21. In other words, it is only necessary to stop the blower 22a of the first space 23a to be cooled in operative connection with the interruption of the refrigerant flow to the first evaporator 18 and to restart the blower 22a in operative connection with the restarting of the compressor 11. Similarly, it is only necessary to stop the blower 22b of the second space 23b to be cooled in operative connection with the interruption of the refrigerant flow into the second evaporator 21 and to restart the blower 22b in operative connection with the restarting of the compressor 11.
Specifically, this passage switching mechanism 30 is also constructed of a three-way solenoid valve and switches a first state in which the downstream portion of the ejector 17 is connected to the bypass passage 31 and a second state in which the downstream portion of the ejector 17 is connected to the second evaporator 21.
Specifically, the operation of the 6th embodiment may be performed in the same way as shown in
Then, when the compressor 11 is stopped and the opening/closing valve 16 is closed at time t11 in
This second branch passage 32 is interposed between the downstream portion of the opening/closing valve 16 and the suction side of the compressor 11 and the passage switching mechanism 30 is arranged at the branch position of this branch passage 32. Specifically, this passage switching mechanism 30 is also constructed of a three-way solenoid valve and switches a first state in which the downstream portion of the opening/closing valve 16 is connected to the branch point Z of the upstream portion of the ejector 17 and a second state in which the downstream portion of the opening/closing valve 16 is connected to the second branch passage 32.
A throttle mechanism 33 is arranged on the upstream side of the second branch passage 32 and a third evaporator 34 is arranged on the downstream side of this throttle mechanism 33.
In the 7th embodiment, the first and second evaporators 18, 21 are integrated with each other and are arranged in the first space 23a to be cooled together with the blower 22a and the temperature sensor 24a. Moreover, the third evaporator 34, the blower 22b, and the temperature sensor 24b are arranged in the second space 23b to be cooled.
In contrast, the intermittent operation of the compressor 11 is determined on the inside temperatures Tr1, Tr2 of both of the first and second spaces 23a, 23b to be cooled. Specifically, when the inside temperature Tr1 of the first space 23a to be cooled decreases to the lower limit set temperature Toff1 and the inside temperature Tr2 of the second space 23b to be cooled does not increase to the upper limit set temperature Ton2, as shown at a time t13 in
The passage opening/closing mechanism 17e of the ejector 17 and the opening/closing valve 16 are brought to a closing state in operative connection with this operation of stopping the compressor 11. The time t1 during which the opening/closing valve 16 is in a closing state and the time t3 during which pressure balance is brought after the compressor 11 is stopped, and the time t2 during which the ejector 17 is in a closing state in the time t3 during which pressure balance is brought can be determined similarly to those in the first to 6th embodiments.
Specifically, this passage switching mechanism 30 is also constructed of a three-way solenoid valve and switches between a first state where the downstream portion of the second evaporator 21 is connected to the bypass passage 35 and a second state where the downstream portion of the second evaporator 21 is connected to the third evaporator 34.
Also in the 8th embodiment, the first and second evaporators 18, 21 are integrated with each other and are arranged in the first space 23a to be cooled together with the blower 22a and the temperature sensor 24a. The third evaporator 34, the blower 22b, and the temperature sensor 24b are arranged in the second space 23b to be cooled.
Also in the 9th embodiment, the lower limit set temperatures Toff1, Toff2, and Toff3 and the upper limit set temperatures Ton1, Ton2, and Ton3 are set in correspondence with the inside temperatures Tr1, Tr2, and Tr3 detected by the temperature sensors 24a, 24b, and 24c.
In the 9th embodiment, it is recommended that the compressor 11 is intermittently operated on the basis of the inside temperatures Tr1, Tr2, and Tr3 detected by the temperature sensors 24a, 24b, and 24c in the following manner. That is, when any one of the inside temperatures Tr1, Tr2, and Tr3 of the first to third spaces 23a, 23b, and 23c to be cooled decreases to the lower limit set temperature and neither of the other two inside temperatures increase to the upper limit set temperatures, the compressor 11 is stopped.
Furthermore, the compressor 11 can be continuously stopped for a period during which none of the inside temperatures Tr1, Tr2, and Tr3 of the first to third spaces 23a, 23b, and 23c increase to the upper limit set temperatures after the compressor 11 is stopped. When any one of the inside temperatures Tr1, Tr2, and Tr3 increases to the upper limit set temperature, the operation of the compressor 11 is started again. Moreover, the opening/closing valve 16 and the ejector 17 can be opened and closed on the basis of the same idea as in the above-described embodiments.
In the 9th embodiment described above, the third evaporator 34 is arranged in parallel to the second evaporator 21. However, in the 10th embodiment, as shown in
The first evaporator 18, the second evaporator 21, and the third evaporator 34 are arranged in separate spaces 23a, 23b, and 23c to be cooled. The 10th embodiment is the same in this point as the 9th embodiment. Hence, the compressor 11 can be intermittently operated in the same manner as in the 9th embodiment.
In the cycle constructions in the 5th to 10th embodiments (
In the 1st embodiment, the opening/closing valve 16 is arranged on the upstream side of the branch point Z. However, in the 11th embodiment, as shown in
Specifically, this three-way valve type opening/closing valve 16 is also constructed of a solenoid valve. This opening/closing valve 16 switches between a valve opening state where the downstream portion (high-pressure passage portion) of the liquid receiver 14 communicates with the upstream passage of the ejector 17 and the branch passage 19 at the same time, and a valve closing state where the downstream portion (high-pressure passage portion) of the liquid receiver 14 is shut off from the upstream passage of the ejector 17 and the branch passage 19.
According to this, by switching the opening/closing valve 16 to the valve closing state in operative connection with the operation of stopping the compressor 11, it is possible to produce the effect of preventing the refrigerant from making flowing noises and to prevent the liquid refrigerant from returning when the compressor 11 is started.
In the 11th embodiment, the throttle mechanism 15 can be arranged on the upstream portion of the opening/closing valve 16 to prevent a liquid hammering phenomenon when the opening/closing valve 16 is opened and closed.
In the 3rd embodiment shown in
According to the 13th embodiment, the opening/closing valve 16 is arranged on the upstream side of the throttle mechanism 20 and hence it is not expected that the effect of preventing a liquid hammering phenomenon can be produced when the opening/closing valve 16 is closed. However, also in the 13th embodiment, by closing the opening/closing valve 16 when the compressor 11 is stopped, in the same manner, it is also possible to produce the effect of preventing the refrigerant from making flowing noises and of preventing the liquid refrigerant from returning when the compressor 11 is started.
The throttle mechanism 15, the opening/closing 16, the ejector 17, and the throttle mechanism 20 of the refrigerant branch passage 19 are combined with each other as an integrated unit 40. Here, the integrated unit 40 is an assembly in which the multiple parts 15, 16, 17, and 20 are previously assembled into an integrated structure. Hence, the whole of this integrated unit 40 can be handled as one component.
The first and second evaporators 18, 21 are also integrated into one structure by brazing or the like as described above to construct an integrated unit 41.
Hence, by combining the integrated unit 40 of the ejector 17 and the like with the integrated unit 41 of the first and second evaporators 18, 21, both of these integrated units 40, 41 can be further integrated into one unit.
This integration can reduce the whole physical size of both of the integrated units 40, 41 and hence can reduce a space when they are mounted to a vehicle. Moreover, because both of the integrated units 40, 41 can be mounted as a single unit, the work of mounting the units in the vehicle and the like can be effectively performed.
Moreover, because it is only necessary to set one refrigerant inlet 42 and one refrigerant outlet 43 for the whole of both of the integrated units 40, 41, refrigerant piping can be easily connected to an external unit.
In the 1st to 14th embodiments has been described the cycle construction in which the liquid receiver 14 is arranged on the downstream side of the radiator 13. In the 15th embodiment, as shown in
When refrigerant having a high pressure more than supercritical pressure such as carbon dioxide (CO2) is used as refrigerant, the ejector cycle device 10 becomes a supercritical pressure cycle and hence high-pressure refrigerant only radiates heat in a supercritical pressure state and is not condensed. Hence, in this supercritical pressure cycle, it does not make sense that the liquid receiver 14 is arranged on the downstream side of the refrigerant radiator 13, and hence a cycle construction having the accumulator 44 as shown in
While the cycle constructions each having the multiple evaporators 18,21, 34 have been described in the 1st to 15th embodiments, the 16th embodiment relates to a cycle construction having only one evaporator 18 as shown in
The accumulator 44 used as a vapor/liquid separator is arranged on the downstream side of the ejector 17, and the vapor and liquid of the refrigerant is separated by this accumulator 44 and the separated vapor-phase refrigerant is introduced into the suction side of the compressor 11. There is provided a branch passage 45 for connecting a liquid-phase refrigerant outlet of the accumulator 44 to the refrigerant suction port 17b of the ejector 17 and the evaporator 18 is arranged in this branch passage 45.
This evaporator 18 is at the upstream portion of the refrigerant suction port 17b and hence corresponds to the first evaporator 18 in the 1st to 15th embodiments, whereas the opening/closing valve 16 is arranged on the upstream side of the ejector 17.
Also in the 16th embodiment, by closing the opening/closing valve 16 when the compressor 11 is stopped, it is possible to produce the same effect as in the 1st embodiment and the like. In the 16th embodiment, the ejector 17 is not provided with the passage switching mechanism 17e but may be provided with the passage switching mechanism 17e as required.
The 17th embodiment is a modification of the 16th embodiment. As shown in
In this regard, examples in which the throttle mechanism 15 in the 1st embodiment is eliminated have been shown in the 16th and 17th embodiments. However, also in the 16th and 17th embodiments, needless to say, the throttle mechanism 15 may be arranged on the upstream portion of the opening/closing valve 16 or the upstream portion of the passage switching mechanism 17e.
In the above-described embodiments, the control unit 25 and the opening/closing member (16, 17e) close the refrigerant circuit in response to the stoppage of the compressor that is provided by the intermittent operation for the compressor. Alternately, the control unit 25 and the opening/closing member (16, 17e) may close the refrigerant circuit in response to a shut down of the electric power supply. The shut down may occur when turning off the power supply switch such as an ignition switch of a vehicle or a power failure. In this case, the compressor simultaneously stops at the shut down. Therefore, the refrigerant circuit is closed when the compressor is stopped in this case too. This shut down operation may be applied in addition to or instead of the operation provided by the above-described embodiments. In addition, the shut down operation can be applied to a refrigeration system using a variable capacity compressor or a refrigeration system using a motor driven compressor. The shut down operation may be obtained by using a valve or an electromagnetic actuator having normally close type function. For example, the valve 16 may be provided with a valve body, a biasing member biasing the valve body in a closing direction such as a spring and an electromagnetic solenoid that actuate the valve body in an open direction when it is energized. Alternately, the control unit 25 may have a post-shut down control means for controlling the opening/closing member (16, 17e) to a closed position after the power supply is stopped. In this case, a control circuit including the control unit 25 have a backup power supply such as a battery or condenser that have a capacity at least sufficient to maintain the control unit 25 and the opening/closing member (16, 17e) functioning until an closing operation is completed. The opening/closing member (16, 17e) may have a position holding type actuator driven by a motor such as a stepping motor.
Hereinafter, the 18th embodiment of the present invention will be described in detail with reference to
In this embodiment, this compressor 11 is rotated and driven by a vehicle driving engine (not shown) via a belt or the like. A refrigerant radiator 13 is arranged on the downstream side of refrigerant flow of this compressor 11. The refrigerant radiator 13 exchanges heat between high-pressure refrigerant discharged from the compressor 11 and outside air (air outside a vehicle compartment) blown by a cooling fan (not shown) to thereby cool the high-pressure refrigerant.
The ejector 17 is arranged at a portion on the more downstream side of refrigerant flow than the refrigerant radiator 13. This ejector 17 is a momentum transport type pump that is pressure reducing means for reducing the pressure of fluid liquid and transports fluid by an entangling action. The ejector 17 is provided with the nozzle portion 17a, which restricts and throttles the area of passage of high-pressure refrigerant flowing from the refrigerant radiator 13 to reduce the pressure of high-pressure refrigerant to thereby expand the refrigerant in an isentropic manner, and the suction portion 17b which is arranged in the same space as the refrigerant jet outlet of the nozzle portion 17a and draws vapor-phase refrigerant from the second evaporator 18 to be described later.
Moreover, a diffuser portion 17d forming a pressure increasing portion of the ejector 17 is arranged on the downstream side of refrigerant flow of the nozzle portion 17a and the suction portion 17b. This diffuser portion 17d is formed in a shape to gradually increase the area of passage of refrigerant and performs an action of reducing the velocity of refrigerant flow to thereby increase the pressure of refrigerant, that is, an action of converting the velocity energy of refrigerant to pressure energy.
Refrigerant flowing out of the diffuser portion 17d of the ejector 17 flows into the second evaporator 21. The second evaporator 21 is arranged in an air passage of a refrigerating unit (not shown) in a refrigerating box R and performs an operation of cooling the inside of the refrigerating box R. Specifically, air in the refrigerating box R is blown to the second evaporator 21 by an electrically driven blower 18a in the cooing unit (refer to
The vapor-phase refrigerant evaporating in the second evaporator 21 is drawn by the compressor 11 and is circulated again in a refrigerant circulating passage. In the ejector cycle device of this embodiment is formed the branch passage 19 that branches off at a portion between the radiator 13 and the ejector 17 of the refrigerant circulating passage and merges with the refrigerant circulating passage.
A throttle member 116 for reducing the pressure of refrigerant is arranged in this refrigerant branch passage 19, and the first evaporator 18 is arranged at a portion on the downstream side of refrigerant flow of this throttle means 116. This first evaporator 18 is arranged next to the second evaporator 21 in such way as to be in an air passing portion in series with the second evaporator 21 and on the downwind side of the second evaporator 21 in the air passage of the cooling unit (not shown) in the refrigerating box R. This first evaporator 18 further cools air in the refrigerating box that is cooled by the second evaporator 21. In this embodiment, the compressor 11 and the frost removing member 121 (defrosting member) are electrically controlled by a control signal from an electric control unit (control unit, hereinafter referred to “ECU”) 25.
Next, construction in accordance with the 18th embodiment of the present invention will be described. In an air passage of the cooling unit (not shown), an electric heater 121 (frost removing member) that heats the first and second evaporators 18, 21 in order to remove frost adhering to the first and second evaporators 18, 21 is arranged on the upstream air side of the first and second evaporators 18, 21.
The first evaporator 18, which is low in evaporation temperature and has frost easily deposited thereon and is not easily increased in temperature, is mounted with a first evaporator temperature sensor (first evaporator temperature detecting member) 122 for detecting temperature such as thermistor. For example, this first evaporator temperature sensor 122 can be mounted at a portion that is most resistant to rising in temperature in the first evaporator 18. The detection signal of the first evaporator temperature sensor 122 is inputted to the ECU 25, and when the frost removing control of melting and removing frost deposited on the first and second evaporators 18, 21 is performed, the frost removing member 121 is energized and controlled by an output signal from the ECU 25.
Next, the operation of the present embodiment will be described in the above-mentioned construction. When the compressor 11 is driven by the vehicle engine, refrigerant that is compressed and brought into a high-temperature high-pressure state is discharged out in a direction shown by arrow and is flowed into the radiator 13. In the radiator 13, the high-temperature refrigerant is cooled by outside air and condensed. The liquid-phase refrigerant flowing out of the radiator 13 flows through the refrigerant circulating passage and branches off from a flow flowing through the refrigerant branch passage 19.
The flow of refrigerant flowing through the refrigerant circulating passage flows into the ejector 17 and the refrigerant is reduced in pressure and is expanded by the nozzle portion 17a. Hence, the pressure energy of the refrigerant is converted into the velocity energy by the nozzle portion 17a and the refrigerant is jetted out at high speed from the jet port of this nozzle portion 17a. At this time, the vapor-phase refrigerant evaporated in the first evaporator 18 is drawn from the suction portion 17b by a pressure drop of the refrigerant.
The refrigerant jetted out of the nozzle portion 17a and the refrigerant drawn by the suction portion 17b are mixed with each other on the downstream side of the nozzle portion 17a and are flowed into the diffuser portion 17d. In this diffuser portion 17d, the area of passage is increased to convert the velocity (expansion) energy of refrigerant into pressure energy and hence the pressure of refrigerant is increased by the diffuser portion 17d. The refrigerant flowing out of the diffuser portion 17d of the ejector 17 flows into the second evaporator 21.
In the second evaporator 21, the refrigerant absorbs heat from air in the refrigerating box that is blown by the electrically driven blower 18a (refer to
Next, the frost removing operation (defrosting operation) will be described.
When the integrated operation time of the compressor 11 reaches a specified time, in order to remove frost adhering to and depositing on the first and second evaporators 18, 21, the compressor 11 is stopped and the frost removing member 121 is energized to heat the first and second evaporators 18, 21, thereby removing frost. The integrated operation time of the compressor 11, as shown in
When the detection value of the first evaporator temperature sensor 122 fixed to the first evaporator 18 reaches the predetermined temperature T, the energizing of the frost removing member 21 is stopped and the compressor 11 is again started to start a refrigerating operation again. At this time, the predetermined temperature T may be varied according to the outside air temperature Tam as shown in
Next, the features and effects of this embodiment will be described. The present embodiment includes: the compressor 11 that draws and compresses refrigerant; the radiator 13 that radiates heat from the high-pressure refrigerant discharged from the compressor 11; the ejector 17 that reduces the pressure of refrigerant on the downstream side of the radiator 13 to thereby expand the refrigerant and draws the refrigerant from the first evaporator 18; the second evaporator 21 that evaporates the refrigerant flowing out of the ejector 17 to thereby obtain a cooling capacity; the first evaporator 18 that evaporates the refrigerant drawn by the ejector 17 to thereby obtain a cooling capacity; the frost removing member 121 that heats the first and second evaporators 18, 21 to thereby remove frost adhering to the first and second evaporators 18, 21; the first evaporator temperature sensor 122 that detects the temperature of the first evaporator 18; and the ECU 25. The ECU 25 controls the frost removing operation of the first and second evaporators 18, 21 to thereby remove frost, and stops the frost removing operation by heating using the frost removing member 121 when the temperature of the first evaporator 18 detected by the first evaporator temperature detection sensor 122 reaches the predetermined temperature T for ending the defrosting operation.
In this embodiment, the first evaporator 18, that is low in evaporation temperature and has frost easily deposited thereon and is resistant to rising in temperature, is provided with the first evaporator temperature sensor 122. According to this embodiment, the first evaporator 18 is heated until the first evaporator 18 reaches the predetermined temperature T. Hence, frost is never left on the first and second evaporators 18, 21 but can be surely removed. Therefore, it is possible to prevent a decrease in cooling efficiency, due to the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, when the frost removing operation of the second evaporator 21 is finished, the heating by using the frost removing member 121 is stopped. Therefore, it is possible to eliminate excessive heating and to limit an increase in temperature of the space R to be cooled and the power consumption required to remove the frost to minimum amounts. Moreover, the frost removing member 121 is arranged on the upstream air side of the first and second evaporators 18, 21. According to this arrangement, heat produced by the frost removing member 121 flows to a downstream air side and hence can heat the first and second evaporators 18, 21 with high efficiency.
Moreover, the frost removing member 121 is constructed with the electric heater 121. According to this, it is easy to use the electric heater 121 as heating means for removing frost. The ECU 25 performs the heating of the first and second evaporators 18, 21 by using the frost removing member 121. According to this, by heating the first and second evaporators 18, 21 using the frost removing member 121 in a state where the compressor 11 is stopped, it is possible to finish removing frost within a short time.
Furthermore, the predetermined temperature T is varied according to the outside air temperature Tam. Normally, the amount of moisture contained by the air is varied and hence the amount of adhering frost is varied according to the outside air temperature Tam. Hence, in order to surely remove frost, the predetermined temperature T is also varied according to the outside air temperature Tam.
In the present embodiment, in the construction in which the second evaporator 21 is arranged on the upstream air side where frost easily deposits, the second evaporator temperature sensor 123 is arranged on the upstream air side of the second evaporator 21. According to this, the first and second evaporators 18, 21 are heated until the temperature of the upstream air side of the second evaporator 21, which is arranged on the upstream air side and to which frost easily adheres, becomes the predetermined temperature T or more, so that it is possible to remove frost with reliability without leaving frost on the first and second evaporators 18, 21. Hence, it is possible to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, when the frost removing operation of the second evaporator 21, which is arranged on the upstream air side and to which frost easily adheres, is finished, the frost removing operation by using the frost removing member 121 is stopped. Therefore, it is possible to eliminate excessive heating and to limit an increase in the temperature of the space R to be cooled and the amount of power consumption required to remove frost to minimum amounts.
In the present embodiment, the accumulator 118 is arranged on the downstream side of the second evaporator 21 so as to respond to load fluctuations and the accumulator temperature sensor 124 is fixed to the accumulator 118 in which low-temperature liquid refrigerant accumulates and to which frost easily adheres.
According to this embodiment, the first and second evaporators 18, 21 are heated until the temperature of the outside wall temperature of the accumulator 118, to which frost easily adheres, becomes the predetermined temperature T or more, it is possible to remove frost with reliability without leaving frost on the first and second evaporators 18, 21. Hence, it is possible to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, when the frost removing operation of the accumulator 118 to which frost easily adheres is finished, the frost removing operation using the frost removing member 121 is stopped. Therefore, this can make it possible to eliminate excessive heating and to limit an increase in the temperature of the space R to be cooled and the amount of power consumption required to remove frost to minimum amounts.
In this embodiment, the multiple temperature sensors 122 to 124 are fixed to the above-mentioned multiple portions having frost easily deposited thereon because the degree of adhesion of frost varies according to the operating conditions even in the above-mentioned portions to which frost easily adheres.
According to this embodiment, the ECU 25 performs the heating of the first and second evaporators 18, 21 until all of the multiple temperature sensors 122 to 124 fixed to the multiple portions reach the predetermined temperature T or more. Hence, it is possible to remove frost with reliability without leaving frost on the first and second evaporators 18, 21 and hence to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, when the frost removing operation at the multiple portions to which frost easily adheres is finished, the heating by using the frost removing member 121 is stopped. Therefore, it is possible to eliminate excessive heating, and to effectively limit an increase in the temperature of the space R to be cooled and the amount of power consumption required to remove frost.
That is, in a normal operation (1), the refrigerant from the radiator 13 is introduced to the nozzle 17a of the ejector 17. In contrast, in the frost removing operation (2) of the first and second evaporator 18, 21, the refrigerant from the radiator 13 flows through the hot gas supply passage 119.
According to this embodiment, the frost removing operation (defrosting operation) of the first and second evaporators 18, 21 can be performed without using a heater. Therefore, it is possible to reduce the size of the frost removing member and hence to reduce cost.
Hereinafter, the 24th embodiment of the present invention will be described in detail by the use of
In this embodiment, the compressor 11, the electrically driven blower 18a are electrically controlled by a control signal from the electric control unit (control unit, hereinafter referred to as ECU). Next, the construction in accordance with the 24th embodiment will be described. Multiple frost removing members 121 for heating the first and second evaporators 18, 21 are disposed in order to remove frost adhering to the first and second evaporators 18, 21. For example, as the frost removing members 121, electric heaters 121 such as non-contact type glass pipe heaters are disposed at the upstream side of the first and second evaporators 18, 21 and at a position between the first and second evaporators 18, 21, which are integrated into one unit in the air passage of a cooling unit (not shown).
Moreover, in this embodiment, the first evaporator 18 that is low in evaporation temperature and hence has frost easily deposited thereon is provided with an evaporator temperature sensor (evaporator temperature detecting member) 122 such as thermistor for detecting temperature. For example, this evaporator temperature sensor 122 is arranged in a portion that is most resistant to rising in temperature in the first and second evaporators 18, 21.
The detection signal of the evaporator temperature sensor 122 is inputted to the ECU 25 and when the frost removing control of melting and removing frost adhering to and depositing on the first and second evaporators 18, 21 is performed, the frost removing member 121 is energized and is controlled by an output signal from the ECU 25.
In this embodiment, the cooling operation and the frost removing operation can be performed similarly to the control operation of
In this embodiment, the ejector cycle device includes: the compressor 11 that draws and compresses refrigerant; the radiator 13 that radiates the heat of high-pressure refrigerant discharged from the compressor 11; the ejector 17 that reduces the pressure of refrigerant on the downstream side of the radiator 13 to thereby expand the refrigerant and draws the refrigerant; the second evaporator 21 that evaporates the refrigerant flowing out of the ejector 17 to thereby exert a cooling capacity; the refrigerant branch passage 19 that branches from the refrigerant cycle including the compressor 11, the radiator 13, the ejector 17, and the second evaporator 21 and causes the ejector 17 to draw refrigerant; the first evaporator 18 that is arranged in the refrigerant branch passage 19 and evaporates refrigerant to thereby exert a cooling capacity; the frost removing members 121 that heat the first and second evaporators 18, 21 in order to remove frost adhering to the first and second evaporators 18, 21; and the ECU 25 that causes the frost removing member 121 to perform the heating of the first and second evaporators 18, 21 to thereby remove frost.
According to this embodiment, the frost removing member 121 is arranged so as to heat both of the first evaporator 18 that is low in evaporator temperature and the second evaporator 21 that is arranged on the upstream air side of the first evaporator 18. Hence, even when heating temperature is set low, it is possible to remove frost with reliability without leaving frost and hence to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, the frost removing members 121 are arranged on the upstream side of the first and second evaporators 18, 21, respectively. According to this embodiment, heat produced by the frost removing member 121 flows downwind and hence the first and second evaporators 18, 21 can be heated with high efficiency. In this embodiment, the frost removing members 121 are constructed with electric heaters 121.
Furthermore, the ECU 25 performs the heating of the first and second evaporators 18, 21 by using the electric heaters 121 in a state where the compressor 11 is stopped. Accordingly, the first and second evaporators 18, 21 can be heated by the electric heater 121 in a state where the compressor 11 is stopped. Hence, it is possible to finish removing frost within a short time. Moreover, in this embodiment, refrigerant is a hydrocarbon (HC)-based refrigerant of a flammable refrigerant. The flammable refrigerant includes a hydrocarbon-based refrigerant (refrigerant substance containing hydrogen and carbon and existing in nature and the like) and this hydrocarbon-based refrigerant includes R600a using isobutene and R290 using propane.
For example, R600a catches fire at a temperature of approximately from 460° C. to 494° C. However, when a glass pipe heater is used as the electric heater 121, the ignition temperature is reduced to a temperature of approximately from 200° C. to 300° C. When a pipe heater is used as the electric heater 121 for heating an object in contact with the object, the ignition temperature is reduced to a temperature of approximately 100° C. Hence, R600a can be used as the flammable refrigerant.
In this embodiment, the electric heater 121 is located to contact both of the first evaporator 18, which is low in evaporator temperature and hence frost easily develops, and the second evaporator 21, which is arranged on the upstream side and hence has frost easily deposited on its upstream side and easily causes clogging. Accordingly, even when heating temperature of the electric heater 121 is set low, it is possible to remove frost with reliability without leaving frost and hence to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
The ejector cycle device shown in
According to this embodiment, there is provided one electric heater 121 that can heat both of the first evaporator 18, which is low in evaporator temperature and hence frost easily develops, and the second evaporator 21, which is arranged on the upstream air side and hence has frost easily deposited on its upstream side and easily causes clogging. Hence, even when heating temperature is set low, it is possible to remove frost with reliability without leaving frost. Moreover, it is possible to prevent a decrease in cooling efficiency caused by the frost adhering to and depositing on the first and second evaporators 18, 21.
Moreover, the frost is removed by means of one electric heater 121 having the same size as a usual single evaporator, so it is possible to effectively use an installation space and to effectively remove frost from the multiple evaporators.
Furthermore, either of the first and second evaporators 18, 21 is provided with the electric heater 121 and the other of them is provided with a member easily absorbing radiant heat, for example, an aluminum plate (radiant heat absorbing member) 128 coated with black paint and the radiant heat from the electric heater 121 is delivered to the aluminum plate 128.
According to this embodiment, the electric heater 121 is provided for heating either of the first and second evaporators 18, 21 and the other of them is heated via the aluminum plate 128 for absorbing radiant heat from the electric heater 121. Hence, even when heating temperature is set low, it is possible to remove frost with reliability without leaving frost and to prevent a decrease in cooling efficiency caused by frost adhering to and depositing on the first and second evaporators 18, 21. It is also recommendable to coat the surface itself of the other first evaporator 18 with black paint so as to provide the surface with feature easily absorbing radiant heat.
According to this embodiment, there is provided the electric heater 121 for heating either of the first and second evaporators 18, 21 and the other evaporator is heated by convection from the electric heater 121. Hence, even when heating temperature is set low, it is possible to remove frost with reliability without leaving frost. Moreover, as to convection, forced convection by the electrically driven blower (air blowing means) 18a is used. Accordingly, it is possible to effectively perform convection with reliability.
Moreover, although a case where the first and second evaporators 18, 21 are integrated into one unit has been described in the 24th embodiment, as shown in
The construction of the 29th embodiment will be described by the use of
In an embodiment shown in
In this embodiment, an evaporator temperature sensor (evaporator temperature detecting member) 122 such as thermistor for detecting temperature is fixed to the first evaporator 18 that is low in evaporator temperature and has frost easily deposited thereon. Preferably, this evaporator temperature sensor 122 is fixed to a portion that is most resistant to rising in temperature in the integrated first and second evaporators 18, 21. The detection signal of the evaporator temperature sensor 122 is inputted to the ECU 25. When the frost removing control of melting frost adhering to and depositing on the first and second evaporators 18, 21 to remove frost is performed, the electric heater 121 is energized and is controlled by an output signal from the ECU 25.
Next, the features and effects of this embodiment will be described. First, the first and second evaporators 18, 21 are connected to each other in such a way as to transfer heat by integrated fins (members for transferring heat) 128a. The electric heater 121 heats the first and second evaporators 18, 21 so as to remove frost adhering to them, and the ECU 25 performs the heating of the first and second evaporators 18, 21 by using the electric heater 121 to thereby remove frost.
According to this, for example, even when only one electric heater 121 is arranged on the upstream air side and heats the upwind surface of the second evaporator 21 to thereby remove frost, the first evaporator 18 arranged on the downstream air side is heated by heat transferred from the second evaporator 21 via the integrated fins 128a, thereby having frost removed therefrom.
In this manner, it is possible to heat both of the first evaporator 18, which is low in evaporation temperature and hence frost easily develops, and the second evaporator 21, which is arranged on the upstream air side, by using one electric heater 121 and hence to remove frost within a short time with high efficiency. Moreover, even when the heating temperature is set low, it is possible to remove frost from the first and second evaporators 18, 21 with reliability without leaving frost and hence to prevent a decrease in cooling efficiency caused by frost adhering to and depositing on them. Furthermore, it is also possible to simplify the control of the electric heater 121.
Moreover, the integrated fins 128a are brought into contact with the electric heater 121. This makes it easy to transfer heat from the integrated fins 128a to the first evaporator 18. Furthermore, the amount of heat conduction of the integrated fins 128a is determined in such a way that a refrigerating capacity required by the first and second evaporators 18, 21 is compatible with a frost removing capacity required by them.
In this manner, for improving the refrigerating capacity (RC), it is preferred to completely separate the first and second evaporators 18, 21. However, when the amount of heat conduction is excessively small, heat cannot be transferred at the time of removing frost and hence the frost removing capacity (defrosting performance DP) is reduced by a large amount. In this manner, the refrigerating capacity (RC) and the frost removing capacity (DP) are contradictory to each other in terms of the amount of heat conduction. In the evaporator of this embodiment, the amount of heat conduction is determined in such a way that the required refrigerating capacity (RC) is compatible with the required frost removing capacity (DP). As to the amount of heat conduction by the integrated fins 128a, it is also possible to think the amount of heat conduction in terms of the number of pieces of the integrated fins 128a or the like as a substitute for the amount of heat conduction when the environment conditions of temperature and the amount of air in the evaporator are the same levels.
Moreover, the heat exchange fins 128 are used as members for transferring heat. These are a portion or the whole of the heat exchange fins 128 constructed of the first and second evaporators 18, 21 are integrated with each other according to the above-mentioned required amount of heat conduction. According to this, it is possible to construct the above-mentioned structure without adding a new component and hence to reduce cost.
In
Moreover, this integrated fins 128a is used for transferring heat from the second evaporator 21 to the first evaporator 18. Hence, within a scope not departing from this feature, these integrated fins 128a may be different from the other heat exchange fins 128b, 128c in material, size and shape, and forming method and may be different from the sizes of the evaporators.
The ejector cycle device shown in
The present invention is not limited to the above-mentioned embodiments but may be variously modified as will be described below. For example, the above-mentioned respective embodiments may be combined with each other. Moreover, although the ejector cycle device of the present invention is used for a vehicle-mounted refrigerating apparatus in the above-mentioned embodiments, the ejector cycle device may be used not only to the refrigerating/cooling apparatus and air conditioning (air cooling) apparatus like this but also a vapor compression type cycle such as a heat pump unit for a water heater and a household refrigerator.
Moreover, either a supercritical pressure cycle or a subcritical pressure cycle using flon-based refrigerant, hydrocarbon (HC)-based refrigerant, carbon dioxide (CO2)-based refrigerant as refrigerant may be used. Here, the term of flon means a generic term of an organic compound containing fluorine, chlorine, and hydrogen and the flon is widely used as refrigerant. The flon-based refrigerant includes a hydro-, chloro-, fluoro-carbon (HCFC)-based refrigerant and a hydro-, fluoro-carbon (HFC)-based refrigerant.
Furthermore, in the 30th embodiment, the accumulator 118 is arranged on the upstream side of the compressor 11 and only vapor-phase refrigerant is caused to flow into the compressor 11. However, it is also recommendable to employ a construction in which a vapor—liquid separator is arranged on the upstream side of the second evaporator 21 and in which only liquid refrigerant is caused to flow into the second evaporator 21. Moreover, it is also recommendable to arrange a receiver, which separates the vapor and liquid of refrigerant and flows only liquid-phase refrigerant to the downstream side, on the downstream side of the radiator 13.
The compressor 11 may be a variable displacement type compressor. Alternatively, it is also recommended that a fixed displacement type compressor 11 is employed and that the operation of this fixed displacement type compressor 11 is controlled in accordance with an on-off control by an electromagnetic switch to control the ratio of the on-off operation of the compressor 11 to thereby control the refrigerant discharge capacity of the compressor 11. Moreover, when an electrically driven compressor is used as the compressor 11, the refrigerant discharge capacity may be controlled by controlling the number of revolutions of the electrically driven compressor 11.
Moreover, as for the ejector 17, a variable flow type ejector can be used. In this case, the open area of refrigerant passage of the nozzle portion 17a of the ejector 17 can be controlled so as to control the pressure of refrigerant jetted from the nozzle portion 17a and the flow rate of drawn vapor-phase refrigerant, based on the degree of superheat of refrigerant at the outlet of the second evaporator 21.
Furthermore, in the above-mentioned embodiments has been described an example in which fixed throttle means 116 such as a capillary tube having a restriction opening set constant is arranged on the upstream side of the first evaporator 18. However, it is also recommendable to employ a variable throttle that can vary the flow rate of refrigerant according to fluctuations in the thermal load of the first evaporator 18. Moreover, it is also recommendable to employ a member (for example, expansion valve), which has a mechanism for detecting the degree of superheat at the outlet of the first evaporator 18 and controls the restriction opening, as throttle means 116.
Furthermore, in the above-mentioned 1st to 17th embodiments, the temperatures (inside temperatures) of the spaces 23, 23a, 23b, 23c to be cooled of the respective evaporators 18, 21, 34 are detected by the temperature sensors 24, 24a, 24b, and 24c. However, in place of these inside temperatures, temperatures relating to the inside temperatures such as surface temperature of the evaporator may be detected.
While the invention has been described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the preferred embodiments and constructions. The invention is intended to cover various modification and equivalent arrangements. In addition, while the various elements of the preferred embodiments are shown in various combinations and configurations, which are preferred, other combinations and configuration, including more, less or only a single element, are also within the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-142476 | May 2005 | JP | national |
| 2005-148470 | May 2005 | JP | national |
| 2005-151588 | May 2005 | JP | national |
| 2005-213272 | Jul 2005 | JP | national |
| 2005-219354 | Jul 2005 | JP | national |
