Smoke extraction system

Information

  • Patent Grant
  • 6776708
  • Patent Number
    6,776,708
  • Date Filed
    Monday, January 27, 2003
    21 years ago
  • Date Issued
    Tuesday, August 17, 2004
    20 years ago
Abstract
The invention discloses a smoke extraction system 10 provided with an infrared smoke detector 16, infrared thermostat 18, A/C sensor 38 and transition door 20. When the smoke detector 16 detects smoke 32 it sends a signal to the thermostat 18 changing the setting to exhaust mode, at the same time the signal is received by the A/C sensor 38 electronics of the transition door 20, which opens the transition door allowing smoke to be vented to the outside. When the air conditioning unit engages the vent mode, the air is vented through the transition door 20 thereby creating a draft that will remove the smoke 32 and vent it outside. The extraction system can be adapted to a central air conditioning system 12.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates generally to smoke extraction and, more specifically, to a smoke extraction system designed to be adapted to new air conditioning units or can be provided as a retrofit unit in itself. The smoke extraction system is provided with an infrared smoke detector, infrared thermostat, A/C sensor and transition door. When the smoke detector detects smoke it sends a signal to the thermostat changing the setting to exhaust mode, at the same time the signal is received by the electronics of the transition door, which opens the transition door, thereby sealing the unit's supply side air, allowing smoke to be vented to the outside. The extraction system can be adapted to a central air conditioning system. One or more smoke detectors having signal transmission capabilities signal the thermostat to engage the venting mode of the air conditioning unit. The thermostat also triggers a signal to the electronics controlling an exhaust portal located within the air condition unit. When the air conditioning unit engages the vent mode, the air is venting through the transition door thereby creating a draft that will remove the smoke and vent it outside.




2. Description of the Prior Art




There are other smoke extraction devices designed for extracting smoke. Typical of these is U.S. Pat. No. 2,586,797 issued to Dunlop et al on Feb. 26, 1952.




Another patent was issued to Sheppard on Jun. 26, 1973 as U.S. Pat. No. 3,741,101. Yet another U.S. Pat. No. 3,826,180 was issued to Hayashi on Jul. 30, 1974 and still yet another was issued on May 20, 1975 to Miller as U.S. Pat. No. 3,884,133.




Another patent was issued to van der Lely on Dec. 2, 1975 as U.S. Pat No. 3,923,096. Yet another U.S. Pat. No. 3,926,101 was issued to Moss on Dec. 16, 1975. Another was issued to Phillips on Dec. 20, 1977 as U.S. Pat. No. 4,063,595 and still yet another was issued on Aug. 23, 1988 to Aniello as U.S. Pat. No. 4,765,231.




Another patent was issued to Natale et al. on Apr. 4, 1989 as U.S. Pat. No. 4,818,970. Yet another U.S. Pat. No. 5,260,691 was issued to Shyu on Nov. 9, 1993. Another was issued to Arceneaux on Apr. 25, 2000 as U.S. Pat. No. 6,053,809 and still yet another was issued on Sep. 12, 2000 to James as U.S. Pat. No. 6,118,381.




U.S. Pat. No. 2,586,797




Inventor: James Dunlop et al.




Issued: Feb. 26, 1952




The invention relates to protection against fumes resulting from fires in buildings and being vented to the outdoors. A system for protecting one portion of a building against fumes from a fire in another portion having an opening connecting it to the first named portion, said system comprising; a collection duct in said other portion adjacent said opening; an exhaust fan having its inlet connected to said duct and its outlet discharging outdoors; operating means for said fan; an air intake on said one portion side of said opening; and means for causing operation of said fan operating means when such fire occurs to draw air through said opening from said air intake into said other portion to create a draft through said opening to oppose the fumes and with said fumes entrained therewith into said duct and to discharge said air and fumes outdoors.




U.S. Pat. No. 3,741,101




Inventor: Albert S. Sheppard




Issued: Jun. 26, 1973




A gravity-operated automatically opening ventilator unit which is easily installed in the roof of a building and which, at a predetermined temperature, will automatically open to vent smoke, gases and heat from the interior of the building to atmosphere.




U.S. Pat. No. 3,826,180




Inventor: Toshikazu Hayashi




Issued: Jul. 30, 1974




This invention relates to a ventilator wherein an electronic circuit is actuated when a detecting element detects the existence of any smoke or gas while a fan is in a manual selected slow rotating node of operation or in a stand by halting position, and then the fan is automatically put into full rotation in order to expel smoke or such gas as carbon monoxide, and also for a specified period after completion of this expelling operation the fan is kept rotating during the above operation through the function of a delay-off circuit, with a shutter of a ventilating window being kept open by means of a switch network.




U.S. Pat. No. 3,884,133




Inventor: Edward J. Miller




Issued: May 20, 1975




A method of controlling smoke, ventilation and fire flash point temperature in a multi-zone building served by a central ventilation system using a divided common return air duct having separate branch damper connections for each zone for directing all return air from a fire zone into the other section of the common return air duct.




U.S. Pat. No. 3,923,096




Inventor: Cornelis van der Lely




Issued: Dec. 2, 1975




A multistory building which is comprised of a plurality of superimposed elongated box-shaped prefabricated sections, each of which encloses a portion of the living space in the building, each said section comprising a floor, at least one wall and a ceiling member, said wall extending higher than the top of said ceiling member, said wall extending higher than the top of said ceiling member whereby an air space constituting a channel for transporting air is defined in each said section by the top of said ceiling member, air conditioning means provided in the building in passage communication with said air space of each said section whereby air conditioned by said air conditioning means is received in said air space, said wall being adjacent said air space and the bottom of the floor of the section next above being adjacent to and defining the top of said air space, each said ceiling member and said floor comprising heat exchange means between said air space and the living space in the sections adjacent each whereby with a difference in temperature between the air in said air space and the air in said living space a heat transfer occurs through said member and said floor relative to said living space each said section having an opening in said ceiling member for the passage of air between said air space and the living space defined by such section, closure means in said opening and adjustment means for selectively opening said closure means, and thermostatic means in the living space provided by such section adapted to control said adjustment means.




U.S. Pat. No. Des. 3,926,101




Inventor: Cyril H. Moss




Issued: Dec. 16, 1975




This invention relates to systems for cleaning smoke from buildings when a fire occurs therein. A fire safety system for use in a building having a plurality of accommodation units and a plurality of communal units providing means of access to said accommodation units, said system including a plurality of smoke detectors in said communal units and means controlled by said smoke detectors and responsive to detection of smoke in one of said communal units to admit air under pressure to that communal unit and to restrict passage of smoke from that communal unit to another communal unit or other communal units.




U.S. Pat. No. 4,063,595




Inventor: Leonard Phillips




Issued: Dec. 20, 1977




An air conditioning system capable of regulating the temperature of incoming air and further comprising safety features relating to the sensing of abnormal conditions within a room or like treated area concerning the detection of fire, smoke or abnormally high temperature conditions. The flow of air from the exterior of the system is directed to the interior of the room or area being conditioned by a fan or like blower element while being conditioned through direct exposure to hot or cold conditioning fluid. Safety features include sensing elements connected to a liquid spray assembly as well as the blower and air intake so as to determine the amount of incoming air pressure as well as regulate the delivery of certain safety liquids such as water, through the spray assembly.




U.S. Pat. No. 4,765,231




Inventor: Michael J. Aniello




Issued: Aug. 23, 1988




Harmful smoke is drawn from rooms in an air conditioned building by way of duct work which supplies conditioned air to the rooms during normal operation. When a potentially harmful level of smoke is detected, supply fan motors associated with the duct work are reversed in direction so as to evacuate the smoke through registers in the rooms and into the duct work. The smoke is then exhausted away from the building occupants through an outside ventilating unit. Accordingly, the building occupants will have sufficient time to evacuate the building safely without succumbing to smoke inhalation.




U.S. Pat. No. 4,818,970




Inventor: Anthony Natale, et al.




Issued: Apr. 4, 1989




A fire condition detection and control system for use with air moving and filtering units. The system includes one or more remote fire condition detection units, which sense heat or smoke and, upon such sensing, transmit a signal indicative of an alarm condition to one or more air moving and filtering units located within a containment area. The transmission is by wireless radio frequency transmission and/or a wired transmission line or cable. The air moving and filtering units detect the alarm condition and disconnect power to the blower motor of the air moving and filtering unit. The receiver and control circuitry may be integral with the air moving and filtering unit, or may be part of a separate control unit that plugs into conventional air moving and filtering units.




U.S. Pat. No. 5,260,691




Inventor: Jia-Ming Shyu




Issued: Nov. 9, 1993




A combination fire alarm/air conditioner, which can immediately detect a fire. The device includes a temperature-sensor and/or a smoke-sensor installed in the room-side air inlet of the air conditioner. Signals generated by the sensor are received by a microcomputer which monitors them based on a threshold and a rate of change of the signals. When the rate of change of the signals exceeds the threshold, the microcomputer produces signals which set off an alarm.




U.S. Pat. No. 6,053,809




Inventor: Henry M. Arceneaux




Issued: Apr. 25, 2000




A system for detecting the presence of smoke within a building and providing means to remove the smoke, into the airspace above the ceiling thereby preventing or at least alleviating smoke inhalation, property damage, and allowing more time for the safe evacuation from the premises. The system is comprised of a conventional smoke detector which activates control means for raising and lowering a generally planar panel which is installed in a ceiling. Smoke is removed from the airspace below the ceiling to the airspace above the ceiling. An optional fan, remote fan relay, exhaust vent and back draft damper further aid in the exhausting of the smoke from the building. A fusible link in the control means protects the ceiling fire rating.




U.S. Pat. No. 6,118,381




Inventor: Robert Wilton James




Issued: Sep. 12, 2000




A system for the detection of fire in an apparatus or device having a fan and a pump, comprising means


20


,


25


for detecting the presence of a pre-condition of fire, control means


30


for deactivating the fan on detection of said precondition, and fire detector means


35


for detecting smoke or fire in the absence of air movement.




While these smoke extraction systems may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described. The smoke extraction system of the present invention is provided with an infrared smoke detector, infrared thermostat, a/c sensor and transition door. When the smoke detector detects smoke it sends a signal to the thermostat changing the setting to exhaust mode, at the same time the signal is received by the electronics of the transition door, which opens the transition door allowing smoke to be vented to the outside. The extraction system can be adapted to a central air conditioning system. One or more smoke detectors having signal transmission capabilities signal the thermostat to engage the venting mode of the air conditioning unit. The thermostat also triggers a signal to the electronics controlling an exhaust portal located within the air condition unit. When the air conditioning unit engages the vent mode, the air is venting through the transition door thereby creating a draft that will remove the smoke and vent it outside.




SUMMARY OF THE PRESENT INVENTION




The present invention discloses a smoke extraction system provided with an infrared smoke detector, infrared thermostat, A/C sensor and transition door. When the smoke detector detects smoke it sends a signal to the thermostat changing the setting to exhaust mode, at the same time the signal is received by the electronics of the transition door, which opens sealing the supply side duct and creating an aperture in the A/C unit housing allowing smoke to be vented to the outside. The extraction system can be adapted to a central air conditioning system. One or more smoke detectors having signal transmission capabilities signal the thermostat to engage the venting mode of the air conditioning unit. The thermostat also triggers a signal to the electronics controlling an exhaust portal located within the air conditioning unit housing. When the air conditioning unit engages the vent mode, the air is venting through the transition door thereby creating a draft that will remove the smoke and vent it outside.




A primary object of the present invention is to provide a heat extraction system.




Another object of the present invention is to provide a heat extraction system designed to be adapted to an existing air conditioning unit or provided as a retrofit unit.




Yet another object of the present invention is to provide a heat extraction system providing an infrared smoke detector.




Still yet another object of the present invention is to provide a smoke extraction system that provides an infrared thermostat.




Another object of the present invention is to provide a smoke extraction system providing an a/c sensor and transition door.




Yet another object of the present invention is to provide a smoke extraction system that when smoke is detected the smoke detector sends a signal to the thermostat changing the setting to exhaust mode, at the same time the signal is received by the electronics of the transition door allowing smoke to be vented to the outside.




Still yet another object of the present invention is to provide a smoke extraction system that vents smoke using the duct work of a central air conditioning system. One or more smoke detectors have signal transmission capabilities signaling the thermostat to engage the venting mode of the air conditioning unit. The thermostat also triggers a signal to the electronics controlling an exhaust portal located within the air conditioning unit. When the air conditioning unit engages the vent mode, the air is vented through the transition door thereby creating a draft that will remove the smoke and vent it outside.




Additional objects of the present invention will appear as the description proceeds.




The present invention overcomes the shortcomings of the prior art by providing a heat extraction system designed to be adapted to an existing air conditioning unit or provided as a retrofit unit. Also, a smoke extraction system that when smoke is detected the smoke detector sends a signal to the thermostat changing the setting to exhaust mode, at the same time the signal is received by the electronics of the transition door allowing smoke to be vented to the outside. A smoke extraction system that vents smoke using the duct work of a central air conditioning system. One or more smoke detectors have signal transmission capabilities signaling the thermostat to engage the venting mode of the air conditioning unit. The thermostat also triggers a signal to the electronics controlling an exhaust portal located within the air conditioning unit. When the air conditioning unit engages the vent mode, the air is vented through the transition door thereby creating a draft that will remove the smoke and vent it outside.




The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views.




The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.











BRIEF DESCRIPTION OF THE DRAWINGS




In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawings in which:





FIG. 1

is an illustrative view of the present invention in use. (Normal condition).





FIG. 2

is an illustrative view of the present invention in use. (Smoke condition).





FIG. 3

is a top view of the a typical ac unit.





FIG. 4

is an illustrative view of the present invention in use. (Normal condition).





FIG. 5

is an illustrative view of the present invention in use. (Smoke condition).





FIG. 6

is a perspective view of the present invention.





FIG. 7

is a block diagram of the present invention in use.





FIG. 8

is a block diagram of the present invention in use.





FIG. 9

is a perspective view of the transition door in the open position.





FIG. 10

is a perspective view of the transition door in the closed position.





FIG. 11

is a wiring diagram for the present invention.











LIST OF REFERENCE NUMERALS




With regard to reference numerals used, the following numbering is used throughout the drawings.






10


smoke extraction system






12


existing air conditioning unit






14


roof






16


smoke detector






17


smoke detector reset button






18


thermostat






20


vent door






22


duct system






24


return duct






26


supply duct






30


door relay






32


smoke






33


fire






36


motor






37


direction arrow






38


A/C sensor






40


microprocessor






42


smoke detector #


1








44


air duct #


1








46


air duct #


2








48


air duct #


3








50


smoke detector #


2








52


smoke detector #


3








64


supply duct opening






66


return duct opening




DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




The following discussion describes in detail one embodiment of the invention. This discussion should not be construed, however, as limiting the invention to those particular embodiments, since practitioners skilled in the art will recognize numerous other embodiments as well. For a definition of the complete scope of the invention, the reader is directed to the appended claims.




Turning to

FIG. 1

, shown therein is an illustrative view of the smoke extraction system


10


in use under non-smoke or normal conditions. The smoke extraction system of the present invention


10


is designed to be adapted to an existing air conditioning unit


12


, e.g., on the roof


14


of an existing structure, or can be provided as a retrofit unit in itself. The smoke extraction system is provided with an infrared smoke detector


16


, infrared thermostat


18


, transition door relay


30


, motor


36


, A/C sensor and transition door


20


. When the smoke detector


16


detects smoke it sends a signal to the thermostat


18


changing the setting to exhaust mode, at the same time the signal is received by the A/C sensor electronics and the transition door relay


30


of the transition door


20


, which opens the transition or vent door


20


allowing smoke to be vented through the vent door


20


, shown closed, to the outside. Also shown is the duct system


22


with return


24


, supply


26


air ducts, and supply duct opening


64


.




Turning to

FIG. 2

, shown therein is an illustrative view of the present invention in use during a smoke condition. Shown is the smoke extraction system


10


venting smoke


32


using the duct system


22


of a central air conditioning unit


12


on roof


14


. One or more smoke detectors


16


having signal transmission capabilities signal the thermostat


18


to engage the venting mode of the air conditioning unit


12


. The thermostat


18


also triggers a signal to the electronics controlling an exhaust portal located within the air conditioning unit. When the air conditioning unit engages the vent mode, the air is vented through the transition door


20


shown by direction arrow


37


thereby creating a draft in the return air duct


24


that will remove the smoke and vent it outside through vent door


20


. Also shown are the door relay


30


, supply air duct


26


, supply duct opening


64


.




Turning to

FIG. 3

, shown therein is a top view of a typical ac unit. Shown is the smoke extraction system of the present invention having a motorized door


20


that under normal conditions remains closed for the A/C unit


12


. If smoke


32


is detected the system engages the venting mode of the central air conditioning unit through the thermostat. Also shown is the return air duct


24


and air flow direction arrows


37


.




Turning to

FIG. 4

, shown therein is an illustrative view of the smoke extraction system


10


in use under normal conditions. Depicted are the normal operating conditions of a central air conditioning unit


12


having the smoke extraction system


10


installed therein. The smoke extraction system


10


has a motorized door


20


with a motor


36


and door relay


30


that under normal conditions remains closed. If smoke is detected the system engages the venting mode of the central air condition unit through the thermostat. Also shown are the A/C sensor


38


, the supply air duct


26


, air flow direction arrows


37


, thermostat


18


, and infrared smoke detector


16


.




Turning to

FIG. 5

, shown therein is an illustrative view of the smoke extraction system


10


in use during smoke conditions. Depicted is the smoke exhaust operating condition of a central air conditioning unit


12


having the smoke extraction system


10


installed therein. At least one smoke detector


16


signals the thermostat


18


to shut down the air conditioning mode if operational and to engage the a/c vent mode. Simultaneously the thermostat


18


signals the A/C sensor


38


which opens the transition door


20


. The A/C vent air is exhausted over the a/c unit duct work shown by arrow


37


creating a draft that draws smoke out of the building and away from the A/C unit. Once a smoke condition has passed, the smoke detector contains a reset buttom


17


whereby the transition door


20


is closed. Also shown are the transition door relay


30


, supply air duct


26


, and air duct system


22


.




Turning to

FIG. 6

, shown therein is a perspective view of the smoke extraction system


10


. The smoke extraction system


10


is designed to be manufactured with an existing air conditioning unit or can be provided as a retrofit unit as shown in the drawing. The smoke extraction system is provided with an infrared smoke detector


16


, smoke extraction system reset


17


, infrared thermostat


18


, A/C sensor


38


, door relay


30


, motor


36


and transition door


20


. When the smoke detector


16


detects smoke it sends a signal to the thermostat


18


changing the setting to exhaust mode, at the same time the signal is received by the electronics of the door relay


30


and motor


36


which opens the transition door


20


allowing smoke to be vented to the outside. Also shown are the air duct system


22


, air return duct


24


, air supply duct


26


and air supply duct opening


64


.




Turning to

FIG. 7

, shown therein is a block diagram of the present invention in use. The block diagram depicts the components of the smoke extraction system


10


and their functional relationship. The infrared smoke detector


16


signals the thermostat


18


to engage the venting system of the A/C unit in addition to signaling the transition door


20


of the smoke exhaust system housing to open. Whereupon, the venting A/C unit will exhaust out the transition door


20


causing a draft through the A/C duct work drawing the smoke to be exhausted away from the A/C unit out the transition door


20


as shown by arrow


37


. Also shown are the A/C unit sensor


38


and door relay


30


.




Turning to

FIG. 8

, shown therein is a block diagram of the present invention in use. The block diagram depicts the components of the smoke extraction system


10


of the present invention having a duct isolation feature wherein the microprocessor


40


automatically shuts any vents in the areas not detecting smoke while keeping the vents open in the areas where a smoke condition is detected thereby increasing the volume of air and smoke transferred there through. The figure shows smoke alarm #


1


,


42


, detecting a smoke condition and leaving the respective vent


44


open while closing vent #


2


,


46


, and vent #


3


,


48


, where no smoke conditions currently exist at detector #


2


,


50


, and #


3


,


52


, thus concentrating the full power of the exhaust system to the area most needed. If a smoke condition becomes detected in one of the other areas then the respective vent will open as needed. Also shown are the A/C unit sensor


38


, door relay


30


, door


20


and air direction arrow


37


.




Turning to

FIG. 9

, shown therein is an illustrative view of the extraction system


10


in use under normal conditions having an open door mechanism. The smoke extraction system has a motorized louvered door


20


with a motor


36


and door relay


30


that under normal conditions remains closed. If smoke is detected the system engages the venting mode of the central air condition unit through the thermostat.




Turning to

FIG. 10

, shown therein is an illustrative view of the smoke extraction system


10


in use during normal conditions having a closed door mechanism. The smoke exhaust system has a motorized louvered door


20


with a motor


36


and door relay


30


. Depicted is the smoke exhaust operating condition of a central air conditioning unit


12


having the smoke extraction system


10


installed therein. At least one smoke detector


16


signals the thermostat


18


to shut down the air conditioning mode if operational and to engage the a/c vent mode. Simultaneously the thermostat


18


signals the A/C sensor


38


which opens the louvered transition door


20


closing the supply air duct opening


64


. The A/C vent air is exhausted through the a/c unit duct work shown by arrow


37


creating a draft that draws smoke out of the building and away from the A/C unit.




Turning to

FIG. 11

, shown therein is a wiring diagram of the present invention. The wiring diagram depicts the components of the smoke extraction system


10


having the following legend: ‘R’—Power, ‘G’—Fan, ‘Y’—Cooling, ‘W’—Heat, ‘C’—Common. The smoke detector


16


signals the A/C sensor to engage the fan in addition to signaling the transition door relay


30


which signals the motor to open the transition door


20


. The A/C unit will exhaust out the transition door


20


causing a draft through the A/C duct work drawing the smoke to be exhausted away from the A/C unit out the transition door


20


.



Claims
  • 1. An air conditioning system for providing a smoke extraction system, the air conditioning system being connected to a duct system of a building, the duct system having an air supply duct and an air return duct, comprising:a) a smoke detector for detecting the presence of smoke and transmitting a smoke signal; b) a thermostat for receiving said smoke signal from said smoke detector and responsively engaging a venting system of said air conditioning system; c) said venting system including a motorized vent door which is thereby triggered to open upon receiving a signal from said thermostat, said motorized vent door being a louvered door movable in a track between a first position closing off an air supply duct opening to the outside and second position at right angles to the first position unblocking said air supply duct opening to the outside; and, d) said motorized vent door being disposed in an enclosure of an air conditioning unit in said air conditioning system whereby air from the air conditioning system is vented to the outside thereby creating a draft in an air return duct so that smoke is removed from an interior of the building.
  • 2. The apparatus of claim 1, further comprising a microprocessor to permit the operation of a plurality of room air vents to be coordinated with the operation of a plurality of smoke detectors whereby the room air vents near a smoke source are opened while the room vents removed from a smoke source are closed in order to accelerate the removal of smoke from the interior of a building.
  • 3. An apparatus for a smoke extraction system for attachment to an existing air conditioning system of a building, the air conditioning system having an air supply duct and an air return duct, comprising:a) a smoke detector whereby the presence of smoke can be detected and a signal can be thereafter transmitted to a thermostat; b) said thermostat receiving said signal and thereafter transmitting another signal to an air conditioning sensor; and c) said air conditioning sensor thereupon triggering the opening of a motorized vent door in an enclosure between an air conditioner in said air conditioning system and said air supply duct upon receiving a signal from said thermostat, thereby creating a draft in the return duct so that smoke is removed from an interior of the building.
  • 4. The apparatus of claim 3, comprising a microprocessor to permit the operation of a plurality of room air vents to be coordinated with the operation of a plurality of smoke detectors whereby the room air vents near a smoke source are opened while the room vents removed from a smoke source are closed in order to accelerate the removal of smoke from the interior of a building.
US Referenced Citations (18)
Number Name Date Kind
2586797 Dunlop, et al. Feb 1952 A
3741101 Sheppard Jun 1973 A
3826180 Hayashi Jul 1974 A
3884133 Miller May 1975 A
3923096 van der Lely Dec 1975 A
3926101 Moss Dec 1975 A
4058253 Munk et al. Nov 1977 A
4063595 Phillips Dec 1977 A
4084744 Wilson, Jr. Apr 1978 A
4765231 Aniello Aug 1988 A
4818970 Natale et al. Apr 1989 A
4944216 McCutchen Jul 1990 A
5260691 Shyn Nov 1993 A
6053809 Arceneaux Apr 2000 A
6118381 James Sep 2000 A
6161764 Jatnieks Dec 2000 A
6474086 Liu Nov 2002 B1
6609967 Sharp et al. Aug 2003 B2