Electric power conversion systems – Current conversion – Encased in plug housing
Reexamination Certificate
1998-11-03
2001-01-23
Han, Jessica (Department: 2838)
Electric power conversion systems
Current conversion
Encased in plug housing
C439S153000
Reexamination Certificate
active
06178106
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to power distribution centers such as those used in automotive vehicle electrical systems, and more specifically to such a power distribution center having improved means for connecting a power supply cable thereto.
BACKGROUND OF THE INVENTION
Power distribution centers (PDCs) are commonly used in automotive vehicles to simplify electrical system wiring by eliminating multi-branch wiring and consolidating fuses, relays, and other electrical components in a single location. A PDC typically comprises a housing having a plurality of integrally formed external receptacles for receiving electrical connectors, fuses, relays and other circuit components. A bus bar is contained within the housing and is supplied with electrical power from the vehicle alternator and/or battery by a power supply cable. The bus bar has a plurality of blade-like extensions which project into some or all of the receptacles in order to make electrical contact with and distribute power to the components inserted therein.
In one known type of PDC, the power supply cable is secured into electrical connection with the bus bar by a nut and bolt. The bolt is inserted through a hole in a flat section of the bus bar and through an eyelet terminal at the end of the cable, then the nut is threaded over the bolt and tightened to urge the eyelet terminal into contact with the bus bar with sufficient normal force to achieve electrical connection therebetween. An example of such a PDC is disclosed in U.S. Pat. No. 5,088,940.
There are significant problems associated with a nut and bolt connection of the type described above. If either the bolt or the nut has stripped or otherwise defective threads, the resulting connection may be poor. The relatively small surface area of contact between the terminal and the bus bar may not dissipate heat effectively, leading to undesirable heating at the contact surfaces. Also, threading the nut onto the bolt requires that a tool be used and that the nut be tightened to the correct degree, thus adding to the time and cost involved in the assembly work.
SUMMARY OF THE INVENTION
It is an objective of this invention to provide a reliable and secure electrical connection between a power supply cable and a power distribution center (PDC).
It is another objective of this invention to provide a PDC that may be connected with a power supply terminal by a quick and a simple assembly process.
In general, these objectives are achieved by a PDC having means for pivotally connecting a terminal with the PDC such that pivoting movement of the terminal relative to the housing inserts the terminal through an aperture formed in the housing and into contact with the bus bar. The pivoting connection between the terminal and the PDC allows the terminal to be securely connected with the bus bar without the need for any tools, and provides a degree of alignment to guide the terminal into the aperture. It also provides leverage so that a worker can easily generate sufficient force to insert the terminal into connection with the bus bar in the presence of a force resisting insertion, such as may be generated by a spring clamp or other means for urging the terminal into contact with the bus bar.
In a first embodiment of the invention, the pivoting connection is provided by a fulcrum disposed on the PDC housing adjacent one end of the aperture. The terminal snaps into engagement with a terminal cover such that a blade portion of the terminal projects downwardly from the cover. The terminal cover has a projection at one end which is inserted beneath the underside of the fulcrum, and the joined terminal and terminal cover is then pivoted downwardly about the fulcrum to insert the blade through the aperture. Latching means may be provided to secure the terminal cover in proximity with the housing to thereby avoid inadvertent removal of the terminal from the inserted position. The lever may also be shaped so as to substantially cover the terminal and the aperture to protect against the entry of contamination into the housing through the aperture.
According to a second embodiment of the invention, a fulcrum is formed integrally with the portion of the bus bar immediately below the aperture. This fulcrum may take the form of a simple hole formed through the bus bar. The terminal is formed with a short projection extending from the upper edge of the blade, and this projection is inserted through the hole in the bus bar such that the engagement between the projection and the hole creates a pivot point. The terminal is rotated about the pivot point to move the end of the terminal opposite from the projection downwardly toward the housing, thus urging the blade of the terminal downwardly through the aperture and into electrical connection with the bus bar. This is a very simple and inexpensively fabricated configuration, achieving the pivoting effect with a minimum number of parts.
According to another feature of the present invention, a spring member is co-located with the connection portion of the bus bar directly below the aperture to urge the terminal blade and connection portion into contact with one another in order to create sufficient normal force between the two elements to ensure good electrical contact.
In a first embodiment, the spring member comprises a flat contact plate having upper and lower edges bent into curved spring portions. The spring member is flattened somewhat and inserted into the housing from below so that the spring portions push against a vertical wall formed on the inside of the housing adjacent the aperture and the contact plate is biased into contact with the bus bar connection portion. Insertion of the terminal blade through the aperture causes the blade to slide between the bus bar connection portion and the spring member, deflecting the spring member slightly and thus generating the desired normal force.
In another embodiment, the normal force is generated by a spring clamp having first and second parallel plates biased toward one another and which fits around the flat contact portion of the bus bar. Insertion of the terminal blade downwardly through the aperture causes the blade to slide between the contact portion of the bus bar and one of the plates of the clamp.
In a third embodiment, a spring clamp is formed integrally with the connection portion of the bus bar by bending an end of the bus bar back on itself to form two parallel contact plates connected along a vertical edge by a spring loop which biases the plates toward one another. Insertion of the terminal blade through the aperture urges the blade between the contact plates. A additional spring clamp may also be provided to supplement the normal force of the clamp formed with the bus bar, the spring clamp fitting over and around the bus bar contact plates.
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Umemoto Hiroshi
Yang Shenghua
Han Jessica
Yazaki North America, Inc.
Young & Basile P.C.
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