Patent Application
20060117791
1. Field of the Invention
The present invention relates to vehicle air conditioning systems including a vapor compression-type, refrigerating cycle and using combustible refrigerant, and, more specifically, to vehicle air conditioning systems having a mechanism which recovers refrigerant from the refrigerating cycle into a refrigerant recovery vessel, as needed.
2. Description of Related Art
In a known, vehicle air conditioning system, for example, in which Freon® refrigerant, commercially available from E.I. DuPont De Nemours and Co., of Wilmington Del. USA, such as HFC 134a refrigerant, is used as the refrigerant for a vapor compression-type refrigerating cycle, even if the refrigerant leaks, because it is incombustible, there is little or no risk of fire or explosion. Generally, such leaks are not considered to create significant risks.
Recently, in order to deal with global environmental concerns, much attention has been paid to the use of a vapor compression-type, refrigerating cycle using refrigerant having a low, heat coefficient. As a possible low heat coefficient refrigerant, natural system refrigerants, such as CO2 and combustible refrigerants have been proposed. Nevertheless, in a known air conditioning system for vehicles, in which refrigerant in a vapor compression-type, refrigerating cycle is changed to combustible refrigerant, if the refrigerant leaks, there may be some risk of fire or explosion because the refrigerant is combustible, and, therefore, it is considered preferable to take measures to reduce, minimize, or eliminate the conditions favorable to such risks.
Although it does not relate to an air conditioning system for vehicles, a structure is known wherein a vessel is provided for recovering combustible refrigerant via the opening and closing operation of an electromagnetic valve of a vapor compression-type, refrigerating cycle using combustible refrigerant. See Japanese Patent Application No. JP-A-2000-171130 (“JP'130”). In the structure described in JP'130, however, because a pipe diverges from a refrigerant pipe between an expansion valve and an evaporator, and because a refrigerant recovery vessel is connected to the divergent pipe, even if this structure is applied to an air conditioning system for vehicles, a design change or alteration of the system would be required and is not easily applied. Further, it may not always be possible to efficiently recover refrigerant by extracting combustible refrigerant from the pipe provided between an expansion valve and an evaporator.
Accordingly, a need has arisen for an air conditioning system for vehicles which may recover refrigerant while reducing, minimizing, or eliminating leakage of the refrigerant and which may recover the refrigerant readily and efficiently without requiring significant changes to the system configuration, when combustible refrigerant is used as the refrigerant in a vapor compression-type, refrigerating cycle.
To achieve the foregoing and other objects, an air conditioning system for vehicles comprising a vapor compression-type refrigerating cycle, which uses combustible refrigerant and comprises a gas-liquid separator, according to the present invention, comprises a refrigerant recovery vessel in communication with the gas-liquid separator and which recovers combustible refrigerant in the refrigerating cycle by the communication with the gas-liquid separator. Further, the system comprises a valve which controls the communication between the refrigerant recovery vessel and said gas-liquid separator in response to an external signal.
In this air conditioning system, it is preferred that the gas-liquid separator and the refrigerant recovery vessel are integral to each other. Further, the valve may be integral with the gas-liquid separator and the refrigerant recovery vessel. Alternatively, a communication path for communicating between the gas-liquid separator and the refrigerant recovery vessel may be disposed at a position outside of the gas-liquid separator and the refrigerant recovery vessel, and the valve is disposed in the communication path.
Various structures may be employed to control refrigerant recovery. For example, a structure may be employed wherein a time period for recovering refrigerant by opening the valve is set at a predetermined time period, and after expiration of the predetermined time period, recovered refrigerant is enclosed by closing the valve. Further, a structure may be employed wherein a pressure detecting device detects a vessel pressure in the refrigerant recovery vessel or a separator pressure in the gas-liquid separator, when refrigerant is recovered by opening the valve, the valve then is closed in accordance with a detected pressure by the pressure detecting device. In this structure, when refrigerant has been recovered by opening the valve, the valve then may be closed when a detected pressure by the pressure detecting device equals or exceeds a predetermined pressure. Further, a structure may be employed wherein a vehicle collision detection device detects or predicts a vehicle collision, and when the vehicle collision is detected or predicted by the vehicle collision detection device, refrigerant in the gas-liquid separator is recovered into the refrigerant recovery vessel by opening the valve. Still further, a structure may be employed wherein a refrigerant leakage detection device detects a leakage of refrigerant in the refrigerating cycle, and when the refrigerant leakage is detected by the refrigerant leakage detection device, refrigerant in the gas-liquid separator is recovered into the refrigerant recovery vessel by opening the valve.
In addition, it is preferred that, when refrigerant in the gas-liquid separator is recovered into the refrigerant recovery vessel by opening the valve, a compressor provided in the refrigerating cycle is stopped.
Moreover, it is preferred that the valve is a valve driven by an electromagnetic solenoid and that the normally, closed-type valve is opened when the electromagnetic solenoid is energized.
In another embodiment, a method is provided for controlling leakage of refrigerant in an air conditioning system for vehicles comprising a gas-liquid separator, a refrigerant recovery vessel, and a selectively openable communication path therebetween. The method comprises the steps of: preselecting a predetermined parameter for stopping refrigerant recovery; detecting a leakage of refrigerant within a refrigerant circuit of the air conditioning system; opening said communication path between said liquid-gas separator and the refrigerant recovery vessel; and closing the communication path when a measured parameter equals or exceeds the predetermined parameter.
In still another embodiment, a method is provided for controlling leakage of combustible refrigerant in an air conditioning system for vehicles comprising a gas-liquid separator, a refrigerant recovery vessel, and a selectively openable communication path therebetween. The method comprising the steps of: preselecting a predetermined parameter for stopping refrigerant recovery; detecting or predicting a vehicle collision; opening the communication path between the liquid-gas separator and the refrigerant recovery vessel; and closing said communication path when a measured parameter equals or exceeds the predetermined parameter. In these methods, the predetermined parameter may be a predetermined time period during which the communication path is open or a predetermined pressure within the refrigerant recovery vessel, such that the communication path is open when a pressure measured within the refrigerant recovery vessel is less than the predetermined pressure. Further, the air conditioning system may comprise a compressor, and these methods may comprise the step of stopping the compressor when the communication path is open.
In the air conditioning system for vehicles according to the present invention, which air conditioning system uses combustible refrigerant as the refrigerant in a vapor compression-type, refrigerating cycle, the refrigerant may be recovered readily and efficiently without requiring significant changes to the system configuration and substantially at a specification of the present system, and leakage of the combustible refrigerant to outside may be reduced, minimized, or eliminated. Therefore, the risk of fire or explosion due to leakage of combustible refrigerant may be reduced, minimized, or eliminated.
Other objects, features, and advantages of the present invention will be apparent to persons of ordinary skill in the art from the following detailed description of preferred embodiments of the present invention and the accompanying drawings.
For a more complete understanding of the present invention, the needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings.
A blower 15 is disposed in air duct 14 through which air passes for air conditioning of a vehicle interior. An inside air introduction port 16 and an outside air introduction port 17 are provided at an entrance of air duct 14, and a switching damper 18 controls the amount of air drawn from both ports 16 and 17, and the drawn air then is sent toward evaporator 13 by blower 15. A portion of this drawn air having passed through evaporator 13 then is sent to heater 19 disposed downstream of evaporator 13. The amount of air having passed through evaporator 13 and through heater 19 may be adjusted by an air mixing damper 20 to vary the amount of air having passed through evaporator 13 and bypassed heater 19. The degree to which air mixing damper 20 is opened may be adjusted by an air mixing damper actuator 21. In this embodiment, at the exit side of evaporator 13, an evaporator exit air temperature sensor 22 detects the temperature of air having passed through evaporator 13, and a refrigerant leakage detection sensor 23 detects leakage of refrigerant from refrigerating cycle 1 at this position. Refrigerant leakage detection sensor 23 may be disposed at another desired position, and further, another refrigerant leakage detection sensor may be added at another appropriate position. Air conditioning system 100 also may comprise respective air discharge ports 24, 25, and 26 downstream of evaporator 13 within air duct 14, such as air discharge ports for a DEFROST mode, a VENT mode, and a FOOT mode. Air discharge ports 24, 25, and 26 may be selected, and their opening and closing may be controlled by dampers 27, 28, and 29, respectively.
Air conditioning system 100 also may comprise a main controller 30. The signals from the above-described evaporator exit air temperature sensor 22 and refrigerant leakage detection sensor 23 are sent to main controller 30. Further, in this embodiment, a signal indicating engine rotational speed 31, a signal indicating vehicle running speed 32, a signal indicating detected pressure from the above-described pressure sensor 11, a signal indicating detected interior temperature from a vehicle interior temperature sensor 33, a signal indicating detected outside temperature from an outside air temperature sensor 34, a signal indicating the intensity of sunshine integral, from a sunshine sensor 35, and a signal from a collision sensor 36 provided as a vehicle collision detection device capable of detecting or predicting a vehicle collision may be sent to main controller 30. Further, from main controller 30, a clutch signal 37 may be sent to clutch controller 4, a displacement control signal 38 may be sent to compressor 3, and an electromagnetic valve control signal 39 may be sent to electromagnetic solenoid 10, respectively.
With respect to the method for recovering combustible refrigerant in the air conditioning system thus constructed, examples of two embodiments are explained as follows.
In a first embodiment, when a vehicle collision is detected or predicted by collision sensor 36 provided as a vehicle collision detection device, electromagnetic solenoid 10 is energized, and combustible refrigerant in gas-liquid separator 7 is drawn into refrigerant recovery vessel 8. Further, in this recovery, when the pressure detected by pressure sensor 11 equals or exceeds a predetermined value, or, when a predetermined time period expires, electromagnetic solenoid 10 is de-energized, thereby stopping the refrigerant recovery.
In a second embodiment, when a refrigerant leakage is detected by refrigerant leakage detection sensor 23 provided in air conditioning system 100, electromagnetic solenoid 10 is energized, and combustible refrigerant in gas-liquid separator 7 is drawn into refrigerant recovery vessel 8. Further, in this recovery, when the pressure detected by pressure sensor 11 equals or exceeds a predetermined value, or, when a predetermined time period expires, electromagnetic solenoid 10 is de-energized, thereby stopping the refrigerant recovery.
When the above-described embodiments of recovery operations are carried out, the drive of compressor 3 is preferably stopped.
Thus, when there is a risk that combustible refrigerant leaks outside of the refrigerating cycle, or when leakage actually occurs, in order to prevent leakage of a significant amount of refrigerant, the combustible refrigerant is recovered quickly into refrigerant recovery vessel 8. Consequently, the amount of refrigerant leakage may be reduced, minimized, or eliminated, and the ability of the system to reduce the risk of fire or explosion may be significantly enhanced. In this structure, as described above, because integral, refrigerant recovery vessel and gas-liquid separator device 9 may be disposed at a position similar to that at which known, gas-liquid separators have been disposed, the refrigerant recovery may be carried out readily and efficiently without requiring significant changes to the system configuration.
Although refrigerant recovery vessel 8 is integral with gas-liquid separator 7 in the above-described embodiment, these components may be formed separately. Further, a structure may be employed wherein the communication between gas-liquid separator 7 and refrigerant recovery vessel 8 is not enclosed within integral, refrigerant recovery vessel and gas-liquid separator device 9. An external communication path may be provided, and a valve, such as an electromagnetic valve, may be provided in the external communication path.
The present invention may be applied to any vehicle air conditioning system comprising a vapor compression-type, refrigerating cycle and using combustible refrigerant, thereby realizing an air conditioning system for vehicles with a significantly reduced risk of fire or explosion, even if combustible refrigerant is used.
While the invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or from a practice of the invention disclosed herein. It is intended that the specification and the described examples are considered exemplary only, with the true scope of the invention indicated by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-352399 | Dec 2004 | JP | national |
