Measuring and testing – Internal combustion engine or related engine system or... – Compression
Reexamination Certificate
1999-06-25
2001-12-11
McCall, Eric S. (Department: 2855)
Measuring and testing
Internal combustion engine or related engine system or...
Compression
C073S118040, C116S268000, C116S270000, C116SDIG002, C340S607000
Reexamination Certificate
active
06327902
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gauge for monitoring the filtering performance of a vehicle filter. More specifically, the present invention relates to a low cost, simplified gauge for helping vehicle owners determine whether their air filter needs replacement.
Air filter restriction gauges are used in connection with an air filter for internal combustion engines. These devices typically sense the level of airflow restriction, and provide an indication of this restriction level by providing some type of display. When the air filter has become so loaded with contaminants that the supply of air required by the engine for its operating efficiency is not being drawn through the filter, the gauge will indicate this and thus alert the operator that the filter requires cleaning or replacement. Some existing devices will also lock themselves in various positions to provide a continuous indication as to how much useful life remains in the air filter before it should be cleaned or changed.
The use of a gauge to monitor the filtering ability of a vehicle's air filter is known in the art. Earlier patents in this area include U.S. Pat. No. 4,369,728, issued to Nelson on Jan. 25, 1983, and U.S. Pat. No. 4,445,456, issued to Nelson on May 1, 1984. These devices provided an incremental visual display to the users or maintenance personnel.
Air filter restriction indicator gauges have been available for quite some time. Initially, these indicator gauges were simply a single stage type gauge where a warning button would pop-up once a predetermined restriction level was achieved. The pop-up type gauges were not believed to be reliable and typically not trusted. The design of these gauges was complex and prone to many variations in performance. Also, this pop-up type gauge was difficult to manufacture due to the number of parts required and the intricacies of their assembly.
Additionally, prior art indicators have not always been easy to fully reset, sometimes resulting in a gauge that may give a false, premature signal that an air filter requires replacement. These false signals result in unnecessary filter maintenance—precisely what the gauge is intended to avoid.
In order to accommodate the locking features of prior indicator gauges, previous systems have required fairly involved and complex lock up mechanisms. Often these gauges comprise separate hinged locking pins which must be appropriately attached and aligned within the gauge. As expected, this has provided a manufacturing challenge to accomplish this necessary alignment. As can be easily appreciated, these types of structures also involve additional steps to assemble.
As most gauges have a locking feature so as to indicate that the predetermined vacuum level has been achieved, it is also necessary to provide reset capabilities. This provides additional design challenges when the lock pin is configured. More specifically, the lock pin must be accessible from the back side. Ideally, the button is depressed to unlock the mechanism. This resetting feature of previous designs which have a separate hinged locking pin structure makes the gauges more complex and costly to fabricate.
SUMMARY OF THE INVENTION
The present invention provides a more cost competitive product by dramatically simplifying the base cap design. In general, a one piece base cap is provided which includes an integral reset button and lock up extension, thus eliminating the need for a separate lock pin assembly. The part is specifically designed to be injection moldable while also providing the necessary functionality. A low cost economical restriction indicator gauge is thus provided with a lower part count and a simplified method of manufacturing.
The restriction indicator gauge is used in internal combustion engines for helping owners, maintenance personnel and operators determine when new air filters are required. The gauge of this invention is attached to the engine between the filter and the air intake and monitors the air pressure sign existing at that point. As is clearly understood, the pressure is likely to be a vacuum as the intake is pulling air into the engine. Once the gauge experiences a vacuum signal of a predetermined level, the gauge will “set,” thus indicating that the vacuum is undesirably high. This then provides an indication that the air filter must be changed.
The gauge of the present invention includes a housing which has an inlet in communication with the air intake system. Within the housing is attached a flexible diaphragm, forming an enclosed chamber inside the housing. As the flexible diaphragm is exposed to the vacuum signal, the diaphragm may be caused to move depending on the level of the vacuum. Attached to the flexible diaphragm is a sealing ring and alignment cup which help to maintain a seal between the internal chamber and the remainder of the gauge. The gauge further has a base cap which is attached to the housing such that it is on an opposite side of the diaphragm from the internal chamber. An integral locking extension in the base cap interacts with the sealing ring to provide the necessary lock up function.
The base cap is a single piece molded structure which is attached to the housing by a snap fit connection. This base cap includes the aforementioned lock pin extension as an integral part thereof. The integral lock pin extension eliminates the need for separate lock pin mechanisms which have been used in prior gauges. As is necessary, this lock pin extension is formed into a hinged reset button structure. As such, the reset button is easily depressed causing appropriate movement of the lock pin to unlock the gauge.
The hinge reset button structure of the present invention is again an integral part of the base cap. The base cap continues to be a single one-piece structure which is easily injection molded. The base cap however is specifically designed to avoid many problems typical to molded plastic parts. That is, the base cap is specifically designed to avoid the “setting” phenomena that may occur. The setting problem is avoided by specifically designing the base cap so that its hinging portion will not be permanently bent into an undesired configuration. By having the lock pin extension appropriately cooperate with other elements of the gauge, the reset button and the hinging element are held in their rest position for a majority of the time. As such, the only time the hinging element is stressed is when the gauge is reset. Consequently, it is highly unlikely that the gauge hinge will take on a set.
The housing additionally includes a clear window which is appropriately positioned to provide an appropriate visual indication. In operation, the vacuum signal creates forces on the flexible diaphragm. These forces can cause the flexible diaphragm to move toward the top of the housing. This causes related movement of the alignment cup and sealing ring. The alignment cup and housing window are specifically designed so that the alignment cup will become increasingly visible as it moves towards the top of the housing. Once the predetermined vacuum signal has been reached and the gauge is “set,” the alignment cup then becomes fully visible in the window. This is accomplished by having the lock pin extension interact with the sealing ring once a desired range of movement has been achieved.
By having the base cap be a single molded part, the parts count for the gauge is reduced. Further, the locking mechanism is greatly simplified, which provides for a product which is much easier to manufacture.
It is an object of the present invention to provide a low cost restriction indicator gauge having a simplified design which is easy to manufacture.
It is another object of the present invention to provide a reliable indicator gauge which will display indications that the gauge has experienced one or more predetermined vacuum levels at its input. This can then signal maintenance personnel that a new air filter is required.
It is yet another object of the present invention to provide an indicator which is highly v
Berry, III Charles Henry
Ferris Gregory Matthew
Engineered Products Company
McCall Eric S.
Oppenheimer Wolff & Donnelly LLP
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