Ventilation – Vehicle – Having automatic control means
Reexamination Certificate
2000-10-05
2001-09-04
Joyce, Harold (Department: 3749)
Ventilation
Vehicle
Having automatic control means
C055S312000, C454S158000
Reexamination Certificate
active
06283849
ABSTRACT:
TECHNICAL FIELD
This invention relates in general to a environmental control system for filtering air in a vehicle cab. More specifically it relates to a control system which controls the flow of fresh and recycled air in a high particulate environment to minimize cab particulate levels and optimize filter life.
BACKGROUND OF THE INVENTION
In industries where workers must operate vehicles, including heavy machinery, in a high particulate environment, it is common for the vehicle to have an air filtration system either incorporated into the vehicle's heating and cooling system or free standing within the vehicle's cab. Filtration systems are essential, as extended exposure to air containing large amounts of particulate can be harmful to the worker. These filtration systems generally consist of a single filter placed to filter fresh and recirculated air within the vehicle's cab. In such systems, there is a trade off between the amount of filtering performed and the filter life. If a fine filter is used to clean the air thoroughly, it must be changed often because it fills with particulate quickly. If a coarse filter is used, it need not be changed as often, but allows a larger amount of particulate to remain in the air. This larger amount of particulate is less desirable because of the increased risk to the worker.
Some systems employ a two stage filter having a fine and a coarse filter to extend the life of the fine filter while still providing thorough filtration of the air. In a two stage filtration system, the air is routed first through a coarse filter, then through a fine filter. The fine filter is then subject to less particulate and lasts longer. This two stage filtration system is a marked improvement over the single filter systems, but both filters must still be changed often. Also, the filter life and efficiency is not maximized because the filter system utilizes both filters regardless of how much particulate is in the air being filtered.
A controlled filtration system that maximizes the life of the filters and thoroughness of the air filtration is needed. Such a system would respond to changing conditions in the cab and optimize the use of the fine and coarse filters to maximize their life and the filtration efficiency.
SUMMARY OF THE INVENTION
The present invention is drawn to a device for filtering particulate from air in a vehicle cab, the vehicle cab having a portal. It has a fine filter and a coarse filter. The fine filter is capable of filtering smaller particulate than the coarse filter. A recirculating air passageway has an inlet originating in the cab and an outlet changeable between a closed position, a fine filter position connecting the outlet to the fine filter, and a coarse filter position connecting the outlet to the coarse filter, for recirculating air within the cab through the filters. A fresh air passageway originates outside the cab and has an outlet changeable between a closed position and a coarse filter position connecting the outlet of the fresh air passageway to the coarse filter, for communicating air from outside the cab to the coarse filter. A sensor is included for sensing when the portal is open and outputting a signal. A controller receives the signal from the sensor and changes the positions of the recirculating and fresh air passageways for a selected period to reduce clogging of the filters.
When the controller senses that the portal is opened for less than a selected time, it changes the recirculating air passageway to the coarse filter position for a first time period. Then, the controller changes the fresh air passageway to the closed position and changes the recirculating air passageway to the fine filter position for a second time period. Then the controller reopens the fresh air passageway to the coarse filter position and continues to keep the recirculating air passageway in the fine filter position.
When the controller senses that the portal is opened for greater than a selected time, the controller changes the recirculating air passageway to the closed position and changes an exhaust air passageway to the open position for a first period of time. Then, the controller changes the fresh air passageway and the exhaust air passageway to the closed position and changes the recirculating air passageway to the coarse filter position for a second time period. Then, the controller reopens the fresh air passageway to the coarse filter position and changes the recirculating air passageway to the fine filter position.
A squirrel cage blower having an axis of rotation has a scroll-shaped housing surrounding the blower. The housing has a housing inlet for receiving air and a housing outlet for discharging air from the blower. The fresh air passageway has an inlet at an inner portion of the housing outlet and an air condition condenser is positioned to receive the discharge of air from an outer portion of the housing outlet. The outer portion of the housing outlet is farther from the axis of rotation than the inner portion.
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Bracewell & Patterson L.L.P.
Joyce Harold
Specific Cruise Systems, Inc.
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