Magazine for enclosing a plurality of circuit boards

Details Magazine for enclosing a plurality of circuit boards Magazine for enclosing a plurality of circuit boards

1997-12-18

2001-03-13

Gandhi, Jayprakash N. (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S688000, C361S756000, C361S796000, C361S797000, C165S080300, C174S016100

Reexamination Certificate

active

06201705

ABSTRACT:

FIELD OF INVENTION
The present invention relates to a magazine and then particularly to a magazine which is adapted to accommodate a plurality of printed circuit boards in side-by-side relationship.
By circuit board is meant a printed circuit board having surface-mounted or hole-mounted discrete or integrated components.
Magazines of this kind include mutually facing inner wall-part surfaces on which mutually opposite and mutually corresponding guide strips are mounted for coaction with mutually opposite edge parts of a circuit board such as to guide a circuit board having a plurality of edge-related contact surfaces into the magazine and into mechanical and electrical coaction between said contact surfaces and magazine-mounted contact strips, or for guiding the circuit board out of said magazine, and means for dissipating heat generated by the circuit board and its components to the outside of said magazine.
Heat is conducted to the outside of the magazine with the aid of a coolant which is exemplified in the following in the form of a cooling airflow. This airflow will primarily be self-circulating, a prerequisite which is fundamental to the following description, although forced airflows generated by fans and blowers are also conceivable, with a larger heat dissipation.
The person skilled in this art will be well acquainted with the measures that should be taken when replacing the cooling airflow with some other form of cooling means.
BACKGROUND
Several different designs of magazines of the aforesaid kind are known to the art.
One type of magazine is known in which a circuit board is placed on or surrounded by a metal casing or the like which is brought into mechanical contact with requisite cooling fins.
Examples of this technology are described an shown in publications;
EP-A1-0 564 315,
EP-A2-0 449 150 and
DE-C2-37 17 009.
U.S. Pat. No. 5,768,924 is also relevant in this context, and describes and illustrates a magazine for electronic equipment which enables the equipment to be readily accessed.
Cables are outed and positioned so as to have no affect, or only a slight affect, on the cooling process through convection within the casing.
It is also mentioned that high power equipment, such as power units, can be mounted on one side of the casing, so as to enable these parts to be cooled by a first fan-controlled airflow, and to cool remaining parts by means of a second fan-controlled air flow.
It is also mentioned that the front and the rear sides have horizontal slots through which cooling air can flow, and an electrically conductive grid or grating behind the slots so as to minimize interference, such as RFI (Radio Frequency Interference).
Publication EP-A1-0 091 733 describes and illustrates a circuit board arrangement in which respective circuit boards (
24
) are displaceably disposed in a casing (
20
,
21
), in mutually opposing guide channels (
22
).
Described in this publication is a cooling module (
1
) which has planar side walls (
2
) and which is end-sealed so that a flow of pressurized cooling air is able to pass into a cooling channel.
A compressed air source is connected to the formed cooling channel and the channel side-walls are provided with nozzles or jets positioned so that respective air flows through respective nozzles are directed onto one or more heat-intensive components.
Publication EP-A1-0 539 341 also teaches an arrangement for cooling electronic equipment or electronic circuit board mounted components. In this case, heat is transferred by radiation.
It will be particularly noted in this case that both a circuit board (
1
) and a cooling plate (
3
) are so treated as to exhibit a high coefficient of IR-radiation (Infrared Radiation), wherewith heat is transferred from the heated circuit board to the relatively cool plate.
Publication U.S. Pat. No. 5,218,516 teaches an electronic module which includes a printed circuit board with electronic components mounted on one side of the board and with the opposite side of said board placed in heat conductive contact with a cold surface, more specifically with cooling fins. The mounted circuit board is enclosed in a casing (
16
) and is therewith isolated from and free from the surrounding atmosphere.
Publication EP-A2-0 472 269 discloses the possibility to increase the contact surface of the circuit board in order to dissipate heat generated within the circuit board, without needing to expose the circuit board or its components to the cooling means.
The disclosures made in publication EP-A 0 234 550 also exemplify the present standpoint of techniques with regard to circuit board cooling in a dust-free environment.
It is also known that heat is emitted from a surface by radiation and by convection.
SUMMARY OF THE PRESENT INVENTION
Technical Problems
When considering the earlier standpoint of techniques as described in the aforegoing, it will be seen that a technical problem resides in the provision of a magazine for accommodating a plurality of vertically orientated printed circuit boards with the aid of simple means, and which provides a completely closed chamber for the circuit boards enclosed in the magazine and still provide conditions whereby a coolant, such as an air flow, can pass through readily formed cooling channels or passageways which are fully closed from the circuit board spaces or circuit board chamber and thereby provide conditions for completely sealing respective closed chambers against the ingress of particles and other contaminants and therewith fully screen respective closed chambers with regards to present EMC- (Electro Magnetic Compatibility) requirements.
It will also be seen that a technical problem resides in enabling conditions to be retained whereby the magazine affords effective EMC-protection while still enabling one or more circuit boards to be readily exchanged and/or the magazine to be supplemented with further circuit boards.
A technical problem also resides in providing a magazine construction which provides a high degree of flexibility with regard to the choice of circuit boards that have different total heat emissions and different distribution of heat-generating surface parts and outer environment solely with the aid of air flow convection as a cooling agent.
It will also be seen that a technical problem resides in providing a magazine whose basic construction is such as to provide effective convection cooling and effective EMC protection and which can also be readily adapted to circuit boards of different standard sizes.
It will also be seen that a further technical problem is one of realizing the significance of permitting the requisite heat transfer to take place from circuit boards to at least one cooling wall surface primarily via radiation, where the cooled and cooling wall surface may be located in the very close proximity of the heat-generating components on the circuit board or a flat surface.
It will also be seen that a technical problem resides in recommending those dimensions applicable for conditions which enable the heat taken up in an outer cooling wall surface to be transferred to a convection air flow passing through the cooling channel.
It will be seen that a technical problem is one of providing a magazine of the kind defined in the introduction in which the opposing cooled wall-parts of an individual cooling channel enclose a circuit board in the form of a casing with a small space between the outer surfaces of the circuit board and an adjacent cooled surface.
It will also be seen that a technical problem resides in providing a magazine in which the coolant is comprised of an air flow which passes through a plurality of mutually parallel cooling channels which are delimited by wall-parts of which two wall-parts are mutually opposed and have a relatively large surface extension and are placed close together with their mutually distal outer surfaces facing towards a respective closely adjacent circuit board position.
It will also be seen that a technical problem is one of creating conditions in a simple manner such that the mutually opposing open end

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