Fan assembly for forcing filtered air into a micro computer case

A fan assembly adapted to be installed into a standard expansion slot of a microcomputer. The assembly comprises a frame, sized to fit into the standard expansion slot, including attachment members adapted to permit attachment of the frame into a standard expansion slot and defining an air passageway through the frame, the air passageway having a first opening coincident to the attachment members and having a second opening positioned away from the attachment members. Additionally, an electric fan is mounted in the frame and positioned to move air through the air passageway from the first opening through the second opening. Finally, an electrical conductor and connector assembly is adapted to be connected to a source of electrical power and to transmit electrical power from the source of electrical power to the electric fan.

FIELD OF THE INVENTION 
 The present invention is a fan assembly adapted to be installed in a 
 standard expansion slot of a microcomputer. 
 BACKGROUND OF THE INVENTION 
 The most typical cause of failure of a microcomputer is dust that has 
 settled on a component of the system and has caused an unwanted electrical
 connection. Unfortunately, currently available microcomputers have little 
 in the way of safeguards against contamination by dust. Most 
 microcomputers are equipped with two fans. A first fan is entirely 
 internal to the computer case and cools the central processing unit (CPU) 
 but does not draw air into or out of the computer. A second fan cools the 
 transformer that provides voltage in the range of 5 to 12 VDC to the 
 computer digital circuitry. The second fan typically draws air over the 
 transformer surfaces and discharges the air through holes in the computer 
 case. The discharged air is replaced by air that enters the computer by 
 other holes in the case that are included for that purpose or by small 
 seams where various case elements fit together. The replacement air is 
 unfiltered and typically contains dust that may cause a computer failure. 
 SUMMARY 
 In a first aspect, the present invention is a fan assembly adapted to be 
 installed into a standard expansion slot of a microcomputer. This assembly
 comprises a frame, sized to fit into the standard expansion slot, 
 including attachment members adapted to permit attachment of the frame 
 into the standard expansion slot and defining an air passageway through 
 the frame, the air passageway having a first opening coincident to the 
 attachment members and having a second opening positioned away from the 
 attachment members. Additionally, an electric fan is mounted in the frame 
 and positioned to move air through the air passageway from the first 
 opening through the second opening. Finally, an electrical conductor and 
 connector assembly is adapted to be connected to a source of electrical 
 power and to transmit electrical power from the source of electrical power
 to the electric fan. 
 In a separate, second aspect, the present invention is a microcomputer 
 adapted to avoid dust related failures and comprising a case defining a 
 set of standard expansion slots and a fan assembly. This assembly includes
 a frame, an electric fan and an electrical conductor and connector 
 assembly. The frame is sized to fit into the standard expansion slot, 
 including attachment members adapted to permit attachment of the frame 
 into the standard expansion slot and defining an air passageway through 
 the frame, the air passageway having a first opening coincident to the 
 case and having a second opening inside the case. The electric fan is 
 mounted in the frame and positioned to move air through the air passageway
 from the first opening through the second opening. Finally, the electrical
 conductor and connector assembly is adapted to be connected to a source of
 electric power and to transmit electrical power from the standard internal
 power port to the electric fan. 
 In a separate, third aspect, the present invention is a method of 
 retrofitting a microcomputer having a case and an unused standard 
 expansion slot to be less susceptible to failure due to dust 
 contamination, comprising the steps of: Providing a fan and filter 
 assembly, including a frame, an electric fan, an electrical conductor and 
 connector assembly. The frame is sized to fit into the standard expansion 
 slot, including attachment members adapted to permit attachment of the 
 frame into the standard expansion slot and defining an air passageway 
 through the frame, the air passageway having a first opening coincident to
 the attachment members and having a second opening positioned away from 
 the attachment members. The electric fan is mounted in the frame and 
 positioned to move air through the air passageway from the first opening 
 through the second opening. The electrical conductor and connector 
 assembly adapted to be connected to a source of electrical power and to 
 transmit electrical power from the source of electrical power to the 
 electric fan. The filter is positioned in the air passageway and adapted 
 to filter particles from air that is being moved from the first opening 
 through the second opening by the fan. The fan and filter assembly is 
 installed into the expansion slot of the microcomputer so that the fan 
 brings air from outside the case through the first opening and the filter 
 and out through the second opening into the interior of the case. 
 The foregoing and other objectives, features and advantages of the 
 invention will be more readily understood upon consideration of the 
 following detailed description of the invention, taken in conjunction with
 the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
 Viewing FIG. 1, a preferred embodiment of the present invention is a fan 
 and filter assembly 10 adapted to be connected into a standard expansion 
 slot of a PC type personal computer or microcomputer 12. Air is drawn 
 through a front opening 14, by a fan 16 drawn through a passageway 18 
 defined by the case 20 of assembly 10 and discharged into the interior of 
 the computer 12 by way of a grated opening 22. The case 20 is also adapted
 to receive a replaceable dust filter 24. Assembly 10 is easily connected 
 to the power supply 26 of the computer by way of a standard Molex 
 connecter 28. As each component that is connected to power supply 26 is 
 typically connected by way of a three-terminal "Y" connector, there should
 be a spare terminal available to connect to the fan assembly 10, 
 regardless of the internal configuration of the computer 12. Assembly 10 
 is powered by 12 VDC power drawn through the connector 28. 
 The basic advantages of the present invention should now be evident. 
 Assembly 10 creates a positive air pressure within computer 12, as opposed
 to the exterior of computer 12. Accordingly, assembly 10 introduces 
 filtered air and the constant introduction of unfiltered air caused by the
 transformer-cooling fan is stopped. As a result, the entrance of dust 
 particles into the computer case 20 is greatly reduced, if not stopped 
 altogether. Accordingly, a substantially dust free environment is created 
 within computer 12, leading to a greatly reduced number of dust related 
 computer failures. 
 Referring specifically to FIG. 2, the front face of assembly 10 is adapted 
 to be installed into a standard expansion slot of a microcomputer, and 
 therefore is in the form of a standard bracket adapted for this purpose. 
 The face is 12.09 cm (4.76 in) wide and is 1.86 cm (0.73 in) tall but 
 narrows on the left hand side (facing assembly 10 [as in FIG. 2]) to 1.105
 cm (0.435 in). A hole 38 is defined on the left hand side, for receiving a
 fastener. On the right hand side, a flange extends outwardly from the 
 paper in FIG. 2 and defines a nick 40 (FIGS. 4 and 5) for receiving and 
 being retained onto the computer frame by a fastener, such as a screw. 
 FIGS. 4 and 5 show an embodiment 60 having two fans 62 and 64 for moving a
 larger volume of filtered air into computer 12. Each fan unit is a square 
 of 8 cm (3.15 in) per side and is 1.4 cm (0.55 in) high. Fan 16 or 60 or 
 62 is preferably a 12 VDC NIDEC brand Mini Fan having dimensions of 
 31/8.times.31/8.times.1/4 available as listed in Catalog 272, 1999 Edition
 from Surplus Center of Lincoln, Nebra. The filter is made of Techx 
 filtration media for dust and smoke filtration, has an efficiency rating 
 of: Minimum NaCl=80%; Minimum DOP=50% and is available from Air Filtration
 Products, Inc. of Tucson, Ariz. 
 The terms and expressions which have been employed in the foregoing 
 specification are used as terms of description and not of limitation, and 
 there is no intention, in the use of such terms and expressions, of 
 excluding equivalents of the features shown and described or portions 
 thereof, it being recognized that the scope of the invention is defined 
 and limited only by the claims which follow.