Abstract:
An automated hose clearing after refrigerant charge method and appropriate apparatus is provided. The method includes detecting a pressure differential between the interiors of a high and low pressure hose on an air conditioning charging unit, determining if a pressure differential exceeds a predetermined threshold and temporarily providing fluid communication between the interiors of the high and low pressure hoses.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application entitled, AUTOMATED HOSE CLEARING AFTER REFRIGERANT CHARGING METHOD, filed Nov. 12, 2004, having a Ser. No. 60/626,942, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to machines for charging air conditioning systems in vehicles. More particularly, the present invention relates to clearing the high pressure hose of refrigerant after charging a vehicle&#39;s air conditioning system. 
     BACKGROUND OF THE INVENTION 
     When charging refrigerant in air conditioning systems, inaccurate measuring how much refrigerant enters an air conditioning system during a charge can effect the air conditioning system performance. Charging machines (sometimes called recovery units) are often used to charge air conditioning systems. 
     After charging some air conditioning systems, the high side service hose of a charging unit may be filled with high-pressure liquid refrigerant. Disconnecting the hose while it is full of refrigerant may cause the system being serviced to be undercharged which can result in poor air conditioning system performance. 
     Accordingly, it is desirable to provide a method and apparatus that allows refrigerant from the high side hose of the charging unit to equalize (thus causing refrigerant from the high side of the system to enter the air conditioning system) with the low side of the air conditioning system before the low side hose is removed from the air conditioning system. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus and method are provided that in some embodiments allows refrigerant from the high side hose of the charging unit to equalize (thus causing refrigerant from the high side of the system to enter the air conditioning system) with the low side of the air conditioning system before the low side hose is removed from the air conditioning system. 
     In accordance with one embodiment of the present invention, a method of clearing the interior of a high pressure hose connected to an air conditioning system is provided. The method includes detecting a pressure differential between the interiors of a high and low pressure hose, determining if the pressure differential exceeds a predetermined threshold, and temporally providing fluid communication between the interiors of the high and low pressure hoses. 
     In accordance with another embodiment of the present invention, a storage media containing code for detecting a pressure differential between the interiors of a high and low pressure hose, determining if the pressure differential exceeds a predetermined threshold, and temporally providing fluid communication between the interiors of the high and low pressure hoses is provided. 
     There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating components of a charging unit used to accomplish clearing of the high side hose according to an embodiment of the invention. 
         FIG. 2  is a schematic diagram illustrating components of the charging unit used to accomplish clearing of the high side hose according to another embodiment of the invention. 
         FIG. 3  is a flowchart illustrating steps that may be followed in accordance with one embodiment of the method or process of clearing the high side hose of a charging unit. 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a charging unit that allows refrigerant from the high side hose of the charging unit to equalize (thus causing refrigerant from the high side of the system to enter the air conditioning system) with the low side of the air conditioning system before the low side hose is removed from the air conditioning system. 
     Examples or aspects of charging units are described in at least some of U.S. Pat. Nos. D433,346; 4,938,031; 5,005,369; 5,248,125; 4,261,178; 4,768,347; 4,809,520; 5,603,223; 6,202,433; 6,334,320; 6,119,475; 6,134,899; 6,134,896; 6,138,462; 5,906,106 and U.S. patent application Ser. No. 10/178,526, all of which are incorporated herein in their entirety. 
       FIG. 1  is a schematic diagram illustrating components of a charging unit  10  used to accomplish clearing of the high side hose according to an embodiment of the invention. While this discussion is primarily focused on charging units, some embodiments of the invention may also be practiced on air conditioning system tester units. 
     The charging unit  10  includes a high side refrigerant hose  16  coupled to a high pressure side  12  of a vehicle&#39;s air conditioning system. Generally, when connected, the high pressure hose  16  is in fluid communication with the high pressure side  12  of the vehicle&#39;s air conditioning system. The hose  16  is attached to the high pressure side  12  of the vehicle&#39;s air conditioning system near the refrigerant exiting the compressor (not shown) of the vehicle&#39;s air conditioning system. A low pressure hose  18  is connected to the low pressure side  14  of the vehicle&#39;s air conditioning system near the refrigerant entering the compressor in the vehicle&#39;s air conditioning system. 
     Fitting  56  on the high pressure hose  16  prevents refrigerant within the hose  16  from exiting the hose  16  when the hose  16  is disconnected from the high pressure side  12  of the vehicle&#39;s air conditioning system. Similarly, fitting  58  is located at the end of the low pressure hose  18  to avoid the refrigerant within the low pressure hose  18  from exiting the low pressure hose  18  when the low pressure hose  18  is disconnected from the low pressure side  14  of the vehicle&#39;s air conditioning system  14 . 
     Located on the high pressure hose  16  is a gauge  17 . The gauge  17  may be a manual gauge  17  as configured to indicate the pressure (gauge pressure, with respect to the ambient pressure) of the refrigerant within the high pressure hose  16 . A similar gauge  19  is located on the low pressure hose  18  and is configured to indicate the pressure of the refrigerant located within the low pressure hose  18 . 
     A pressure transducer  20  is located on the high pressure hose  16  and is connected by connector  40  to a controller  28 . The pressure transducer  20  is configured to indicate the pressure of the refrigerant within the high pressure hose  16  and indicate that pressure by a signal to the controller  28 . The low pressure hose  18  also has a pressure transducer  22  that is configured to indicate the pressure of the refrigerant located within the low pressure hose  18 . The pressure transducer  22  is connected to the controller  28  via a connector  42  that is configured to indicate to the controller  28  the pressure of the refrigerant within the low pressure hose  18  via a signal. 
     A shunt or a connector hose  30  connects the high pressure hose  16  with the low pressure hose  18  via valves  24  and  26 . In some embodiments of the invention, valves  24  and  26  are one-way solenoid valves and are connected to the controller  28  via connectors  44  and  46 . Further, valves  24  and  26  are configured to open or close, to allow fluid communication of the refrigerant between hose  16  and hose  18  via hose  30 , depending on signals transmitted by the controller  28 . 
     An end  32  of the high pressure hose  16  is shown truncated and is connected to other parts of the charging unit  10  for other purposes such as, for example, charging the air conditioning system. Likewise, an end  34  of the hose  18  is also shown truncated and connects to other parts of the charging unit  10  not associated with the invention. The controller  28 , in some embodiments of the invention, is a programmable microcontroller or a Field Programmable Gate Array (FPGA) and has a power input  52  in order to provide power to the controller and, in some embodiments of the invention, also the valves  24  and  26 . 
     An input device  36 , which in some embodiments of the invention, includes a keypad, is connected to the controller  28  by a connector  48 . A display device  38  is also connected to the controller  28  by a connector  50 . In some embodiments of the invention, the display device may be a LED screen or any other suitable display means. In some embodiments of the invention, the display device  38  may include an audio output device  54 . Further, in other embodiments of the invention, the audio output device  54  may be located separately from the display device  38 . 
       FIG. 2  is a schematic diagram illustrating components of the charging unit  10  used to accomplish clearing of the high side hose according to another embodiment of the invention.  FIG. 2  is similar to  FIG. 1  except that as shown in  FIG. 1 , two valves  24  and  26  connecting the connector hose  30  to the high pressure hose  16  and low pressure hose  18  are replaced in  FIG. 2  by a single valve  60  located on the connector hose  30 . 
     The single valve  60  connects the high pressure hose  16  to the low pressure hose  18 . The single valve  60  is then connected to the controller  28  by connection  62 . As shown in  FIG. 2 , communication between the high pressure hose  16  and the low pressure hose  18  is controlled by the single valve  60 . The single valve  60  selectively provides two-way communication of refrigerant through connector hose  30  to one or the other of the high and low pressure hoses  16  and  18 , respectively, according to signals received from the controller  28 . 
     Two one-way valves  24  and  26  may be used to provide two-way communication between hoses  16  and  18 , or a single two-way valve  60 , as shown in  FIG. 2  may be used, as either design, or other suitable designs are in accordance with the spirit of invention. Thus, any suitable arrangement providing for fluid communication between the hoses  16  and  18  may be appropriate. 
     Now that two examples of the suitable charging unit  10 , as shown in  FIG. 1  and  FIG. 2 , have been described for performing some embodiments of the invention, a method, in accordance with the invention, suitable for use on the charging unit  10  shown in both  FIG. 1  and  FIG. 2 , will now be described. 
       FIG. 3  is a flowchart illustrating steps that may be followed in accordance with one embodiment of the method or process of clearing the high side hose of a charging unit. In some embodiments of the invention, the method  100  is performed by the charging unit  10  which is controlled by the controller  28 . The commands to perform the method  100  are embedded in a software program running on the controller  28 . Once the charging unit  10  or testing unit has completed its charging of the vehicle&#39;s air conditioning system, it is possible that a significant amount of air conditioning fluid (refrigerant) is retained within the high pressure hose  16 . In order to remove a large portion of the refrigerant left within the high pressure hose  16  and place it into the vehicle&#39;s air conditioning system, a method  100 , in accordance with the invention, is employed. 
     The air conditioning fluid within the high pressure hose  16  is placed in fluid communication to the low pressure hose  18 , which allows the fluid to flow from the high pressure hose  16  into the low pressure hose  18  and into the vehicle&#39;s air conditioning system. A detailed description of the method  100 , as shown in  FIG. 3 , will now follow. 
     Once charge routine  64  or test routine is completed, the method  100  operates. At the first step  66 , the controller  28  compares the pressure within the high pressure hose  16  to the pressure within the low pressure hose  18 , as reported by the pressure transducers  20  and  22 . If the pressure within the high pressure hose  16  exceeds a certain first threshold, which in some embodiments, is about 10 psi, then the controller  28  will initiate a hose clearing routine comprising, in some embodiments, steps  68  through  86 , as shown in  FIG. 3 . 
     If the controller  28  determines that the difference in pressure between the high pressure hose  16  and low pressure hose  18  exceeds the first threshold, then in the next step  68 , a message is shown on the display device  38 . The message can be, for example, indicated in bubble  70 , which instructs the user to disconnect the high side coupler  56  from the air conditioning system  12  and press a start key at step  72  on the keypad input device  36  to equalize the hoses  16  and  18 . The high side hose  16  is then disconnected from the high side of the air conditioning system  12  by the operator. The fitting  56  will prevent refrigerant from leaking out of the hose  16 . 
     Once the start key is pressed, as indicated in step  72 , the controller  28  will generate outputs in step  74  to the high side solenoid valve  24  and the low side solenoid valve  26  to allow fluid communication between the high pressure hose  16  and the low pressure hose  18  via the valves  24  and  26 , or alternately, the single valve  60 , and the connecting hose  30 . 
     In some embodiments of the invention, a one second delay, as indicated in step  76 , will occur and the next step  78  will be used to cause the controller  28  to send a signal to the display device  38  to indicate a message to a user as shown in bubble  80  that the machine is equalizing pressure. Then at step  82 , the controller  28  will compare the pressure within the high pressure hose  16  and the low pressure hose  18  of the refrigerant within the respective hoses as reported by the pressure transducers  20  and  22 . The controller compares those pressures to see if it is less than or equal to a certain second threshold, which in some embodiments of the invention, is about 5 psi. 
     If the controller  28  determines that the pressure differential within the hoses  16  and  18  is equal to or below the second threshold, then the outputs to solenoid valves  24  and  26  or  60  will end, causing the solenoid valves  24  and  26  or  60  to go to a position wherein fluid communication is no longer available between the interiors of hoses  16  and  18  via the valves  24  and  26  or  60  and the connecting hose  30 . 
     In an embodiment of the invention, the output  74  from the controller  28  goes to the dual direction single valve  60 . In the alternative, the output  74  may also go to the single directional solenoid valves  24  and  26 . Correspondingly, in one embodiment, the output  74 , when shut off, is shut off to the dual directional single valve  60 . In the alternative, the output  74 , when shut off, is shut off to the valves  24  and  26 . The result of permitting communication between the high and low pressure hoses  16  and  18  via the valves, whether  60  or  24  and  26 , and the connecting hose  30  is the same. 
     In some embodiments of the invention, the controller  28  may move to step  84  from step  82  even if the pressure differential between the interior hoses  16  and  18  is greater than the second threshold if the fluid communication via connector hose  30  and valves  24  and  26  or valve  60  is open for longer than a certain amount of time, which, in some embodiments of the invention, is about 30 seconds. Thus, in some embodiments of the invention, the interiors of high pressure hose  16  and low pressure hose  18  are in fluid communication via the connector hose  30  and valves  24  and  26  or valve  60  for a predetermined period of time or until the pressure within high pressure hose  16  and low pressure hose  18  is equal to or less than the second threshold or for a certain length of time, whichever event occurs first. 
     Thus, the fluid communication depends on time and pressure. Then, as shown in step  84 , the valves  24  and  26  or  60  close, thus ending fluid communication between the interior high pressure hose  16  and low pressure hose  18 . 
     Returning to step  66 , if the controller  28  determines that the pressure differential between the refrigerant in hose  16  and hose  18  does not exceed the first threshold, then the method jumps to step  88  where a signal will be sent to the display device  38  to indicate to a user to remove both hoses  16 ,  18  from the vehicle and press start to recover hoses, as indicated in bubble  90 . Once the start key, located on the keypad of the input device  36 , is pressed at step  92  a normal hose clear operation  94  will be undertaken, ending the method according to an embodiment of the present invention. 
     In some embodiments of the invention, once the fluid communication between the high pressure hose  16  and low pressure hose  18  has ended, then, as indicated in step  86 , an audio output  54  will make a noise to alert the operator, which, in some embodiments of the invention, is to beep twice. Then the next step  88  is to indicate on the display device  38 , to remove the hose  18  from the vehicle and press start to initiate the hose recover clearing routine. 
     Embodiments of the invention include storage media containing executable code for performing methods in accordance with the invention. The storage media may be any type of computer readable storage media such as floppy discs, CD, DVD, flash memory, and the like. 
     The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.