Gas separation: apparatus – With signals – indicators – measuring – or testing means – Pressure measuring means
Reexamination Certificate
1999-08-31
2001-02-20
Smith, Duane S. (Department: 1724)
Gas separation: apparatus
With signals, indicators, measuring, or testing means
Pressure measuring means
C055SDIG003, C073S031040, C116S268000, C116S271000, C116SDIG002
Reexamination Certificate
active
06190442
ABSTRACT:
FIELD OF THE INVENTION
The field of the present invention is that of fluid filter cleanness gauges. More particularly, the field of the present invention is that of a gauge to determine the cleanness of a filter used in a heating, ventilation, or air conditioning (HVAC) system.
PRIOR DEVELOPMENTS
Most conventional HVAC systems for homes or light commercial building use have a replaceable incoming air filter. Additionally, many vehicle HVAC systems also have replaceable filters. The filter is used to entrap dust and other foreign matter in the air and to prevent their distribution into the HVAC machinery. The filter is also used to prevent dust or other foreign matter from entering the interior environment of the building or vehicle. As the filter is fouled and accumulates dust, a greater pressure drop is experienced as the air passes through the filter. If the filter is not replaced this pressure drop can become excessive and reduce the efficiency of the HVAC system.
To prevent a reduction in efficiency, the HVAC operator should appropriately change the air filter. However, fouling of the filter is dependent upon many factors including the exterior and interior environments and the rate of usage of the HVAC system. Therefore, fouling of the air filter is not always linear with respect to time. However, many filter replacements were completed on a time-based formula which may or may not accurately reflect the fouling of the filter.
To overcome the above-noted haphazard approach to filter replacement, filter cleanness gauges have been provided. A filter cleanness gauge typically monitors filter cleanness by monitoring the pressure differential between an ambient air reservoir and the plenum between the filter and the blower of the HVAC system. A prior filter cleanness gauge is shown and described in Dwyer, et al., U.S. Pat. No. 3,024,655. Dwyer provides a filter gauge which has a body of molded transparent plastic material having a vertically positioned float tube. The upper end of the float tube communicates with the plenum chamber at the suction side of the air circulating fan of the HVAC system. The float tube has inserted therein a float ball. Although the Dwyer filter gauge performs in a satisfactory manner, it brings forth certain disadvantages. The first disadvantage is that the plastic molding is somewhat complex. The second disadvantage is that the filter gauge can ingest dust and other foreign matter into the float chamber. Over a period of time, the dust and foreign matter can cause the float to operate improperly or to be obscured from easy viewing. Another filter cleanness gauge is provided by the Honeywell S830A filter cleanness gauge. The Honeywell filter cleanness gauge has a diaphragm member and therefore is less susceptible to malfunction due to the ingestion of dust in the air. However, the Honeywell air cleanness gauge is relatively large and bulky, requires electrical connections, and is relatively expensive. Although the aforementioned filter cleanness gauges have been successfully used, it is a constant desire to provide such a gauge with equal or superior functioning characteristics while at the same time providing a gauge at a lower manufacturing cost. It is also desirable to provide a filter cleanness gauge which does not require a costly diaphragm member. It is also a desire to provide a filter cleanness gauge which does not utilize a diaphragm member but is less susceptible to fouling due to the ingestion of dust into the gauge from an opening to the ambient air.
SUMMARY OF THE INVENTION
To meet the above-noted and other desires the revelation of the present invention is brought forth. In a preferred embodiment the present invention brings forth a filter air pressure cleanness gauge that is free from any requirement of utilization of a diaphragm member. The filter cleanness gauge of the present invention also provides a freedom from fouling due to dusty ambient air conditions. Furthermore, the present invention provides the liberty of remote installation of the filter cleanness gauge. Still further, the present invention in a preferred embodiment provides the liberty of an air filter cleanness gauge which can be readily modified for different filter pressure conditions with the change of one small component, therefore providing a single filter cleanness gauge which can function in a plurality of filter conditions without the necessity of extensive change of the filtering cleanness gauge design or dimensions.
In a preferred embodiment, the present invention provides a filter cleanness gauge which includes a housing with a transparent cover. The housing has a first opening into the atmosphere. The first opening has a variable orifice. The housing has a second opening spaced away from the first opening. The second opening has fluid communication with a fluid source exposed to the filter. A pivotal vane is mounted within the housing and provides a pressure boundary between the first and second housing openings wherein a pressure differential between the atmosphere and the fluid source exposed to the filter causes the vane to pivot to indicate a pressure differential representative of the cleanness of the filter.
It is an object of the present invention to provide a filter cleanness gauge. It is an object of the present invention to provide a filter cleanness gauge which does not utilize a diaphragm. It is an object of the present invention to provide a filter cleanness gauge which in a preferred embodiment can be protected from fouling due to dust or foreign matter in ambient air. It is an object of the present invention to provide a filter cleanness gauge which can be utilized in a multitude of pressure ranges and which can also be remotely mounted. It is an object of the present invention to provide an air filter cleanness gauge with a dial presentation that is easy to read and interpret. It is an object of the present invention to provide an air filter cleanness gauge with a straightforward calibration procedure. It is an object of the present invention to provide a filter cleanness gauge which is easy to install, can be remotely mounted and is easy to assemble at a low cost. It is still further an object of the present invention to provide a filter cleanness gauge which can be used with different blower-filter combinations such as warm air furnaces, air conditioners, automotive cabin air filters, etc. It is still further an object of the present invention to provide a filter cleanness gauge with a pivotal vane wherein the pivotal vane can be varied in the molding procedure to accommodate different pressure differential sensitivities.
The above features and advantages of the present invention will be apparent from the following description of the preferred embodiment considered in conjunction with the accompanying drawings.
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Dykema Gossett PLLC
Smith Duane S.
Tishken Products Co.
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