Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-11-09
2001-01-30
Larkin, Daniel S. (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
Reexamination Certificate
active
06178809
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to detection of leaks in heating, ventilating, refrigeration, and air conditioning systems, and more particularly to dyes and the techniques for introducing them into such systems during their initial assembly, or any reassembly, permitting early detection of leaks, both initially and at some future time.
2. Background Art
A search of the background art directed to the subject matter of the present invention disclosed the following U.S. Patents:
ISSUE
U.S. Pat. No.
INVENTOR
DATE
2,096,099
Gaugler
Oct
1937
3,234,045
Larsen
Feb
1966
3,572,085
Packo
Mar
1971
3,770,064
Bartlett
Nov
1973
4,690,689
Malcosky
Sep
1987
4,758,366
Parekh
Jul
1988
5,149,453
Parekh
Sep
1992
5,167,867
Quaife et al
Dec
1992
5,279,967
Bode
Jan
1994
5,357,782
Henry
Oct
1994
5,421,192
Henry
Jun
1995
5,440,919
Cooper
Aug
1995
Based on a thorough review of the above identified patents, it is believed none of the above teach, disclose, or claim the novel combination of elements and functions found in the improved methods taught by the present invention.
Fluorescent leak detection dyes to find leaks in air conditioning systems have been in use since about 1984. Such systems are taught in the above-noted Parekh, Henry, and Cooper patents. Parekh teaches the use of perylene dyes in finding leaks in air conditioning systems that contain chlorofluorocarbon (CFC-12) refrigerant, while Henry is the first to teach the use of naphthalimide dyes in finding leaks in both CFC-12 and hydrofluorocarbon (HFC-134a) refrigerant and HVAC systems.
Cooper teaches and claims the placement of a dye for leak detection purposes on a substrate material capable of absorbing the leak detection additive. The dye is placed on the substrate and allows the additive to be absorbed into the substrate after which the substrate with the absorbed dye is installed into a component of the refrigeration system through which refrigerant circulates when the system is operated.
Most of these patents teach the use of fluorescent leak detection after the system has left the factory and is in use in the field. In the field, it is possible to charge a system by a method of dye injection using the refrigerant as a vehicle for moving the dye into the system. Various types of injectors and mist diffusers exist for this purpose.
Yet another method of leak detection employed in after-market locations teaches the use of an electronic halogen detector. Electronic refrigerant leak detectors are presently also used in the vehicle assembly line to check for leaks in the air conditioning system. However, due to the inaccessibility of many fittings in the very limited time available to run the air conditioning system in a new automobile or truck assembly plant, and the possible existence of turbulence of air at the check site, this particular leak detection method fails to detect many leaks in the usual assembly line environment.
Thus, it can be obvious that a problem exists in the placement of suitable leak detection dyes into air conditioning systems at such time as the system or its components are assembled. If effective, filling during the assembly enables the air conditioning system to be tested for leaks to provide a quality assurance tool prior to shipment of the system, provided sufficient time is available to operate the system. It also facilitates checking the system later in the field for leaks without the need to recharge the system with additional refrigerant and dye. Thus, this arrangement would reduce the amount of refrigerant released into the atmosphere, providing an environmental benefit.
As noted above, it is possible to utilize dye injectors and mist diffusers to place appropriate dyes in an air conditioning system. However, in the production environment, several problems exist with this arrangement. Generally speaking, such methods are usually too time consuming for production purposes as they involve hooking up and then unhooking hoses to an air conditioning system while the system is on the assembly line. Secondly, such methods can be messy if there is a spillage, which is likely to occur under time constraints present in the usual assembly line environment. It has also been determined that such methods require the flow of the refrigerant through the injector and diffuser to propel the dye into the HVAC system. Finally, such methods would require modification of the existing vehicle assembly line refrigerant charge equipment to inject dye into the vehicle air conditioning system. Accordingly, vehicle and HVAC equipment manufacturers are looking for ways to insert dyes into an HVAC system, rapidly, cleanly, and without the need for the presence of refrigerant at the time of dye insertion.
Accordingly, the methods that are going to be described hereinafter for effecting introduction of leak detection dyes into HVAC systems were not taught previously for several reasons. One of these is the fact environmental awareness was not as prevalent in society while environmental legislation was in no way as stringent as is currently the case. Such restrictions have caused vehicle and HVAC equipment manufacturers to exhibit a far greater interest in limiting the number of leaks in their vehicles so as to reduce the amounts of refrigerant released into the atmosphere. The cost of refrigerants has risen dramatically over the past few years. In the past, it was relatively inexpensive to recharge or top off an air conditioning or HVAC system. This is no longer true because chlorofluorocarbon refrigerants, such as CFC-12 are in the midst of phase-out due to their high ozone depletion potential. Accordingly, they have been replaced by more ozone friendly refrigerants, such as HFC-134a (a hydrofluorocarbon refrigerant), which cost substantially more than the CFC-12 type refrigerants, based on costs of a few years ago. Subsequently, the CFC-12 refrigerant that is currently sold is substantially more expensive because of a federal tax imposed in conjunction with the phase-out of chlorofluorocarbons. Also, in order to prevent customer complaints which accompany the recharging of such HVAC systems with high priced refrigerants, vehicle manufacturers are doing their best to eliminate the need for recharging by reducing the number of leaks in the systems they manufacture.
It has also been found desirable to utilize a method of leak detection that does not require the air conditioning system or HVAC to be recharged prior to leak detection because the dye is already in the system from prior insertion at the time of the vehicle or HVAC equipment assembly.
Yet another reason is that automotive manufacturers currently have a much greater awareness of the necessity of providing customer satisfaction and reducing warranty costs. Manufacturers have continuously raised their standards for quality assurance and now desire to present as leak-free a system as possible to the consumer. Where such conditions are not possible, they consider it necessary to find the leak as quickly as possible once the vehicle is in the field. This desire comes not only from the automobile manufacturer, but also from the dealer networks that request that the fluorescent dye be active in the vehicle's air conditioning system when it leaves the factory.
A final reason for the utilization of this method of leak detection is the added prevalence of leaks due to the smaller molecular size of the HFC-134a refrigerant versus the previously utilized CFC-12.
Another approach to solving this particular problem involved the addition of ¼ ounce of perylene liquid dye into a desiccant container prior to its being installed in the air conditioning system accumulator. In such an arrangement, introduction of this dye was usually too messy. Accordingly, the object of the present invention is to present a satisfactory method for inserting the dye into an air conditioning, refrigeration, or other HVAC system at the point of manufacture.
SUMMARY OF THE INVENTION
Accordingly, it is the object of the present invention to provide an
Bright Solutions Inc.
Fish & Richardson P.C.
Larkin Daniel S.
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