Electronic device

Details Electronic device Electronic device

1999-12-15

2001-07-24

Nappi, Robert E. (Department: 2837)

Electricity: motive power systems

Limitation of motor load, current, torque or force

C361S712000, C361S734000

Reexamination Certificate

active

06265840

ABSTRACT:

FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an electronic device for a motor vehicle, having an electronics unit designed for switching high currents in a two-part housing, a capacitor unit being present to suppress the interference signals produced by the high currents.
Controllers are known which, in addition to the control electronics, also contain a power output stage for driving an actuator in the motor vehicle. For driving the actuator, such as an electric motor for window lifting mechanisms or for producing a valve stroke in a motor vehicle, the power output stages supply high currents. In the case of clocked driving, the switching of the high currents produces interference signals inside the controller, the levels of these interference signals being many times higher than the levels of the signals processed by the control electronics. The physically close arrangement of these different circuits in a controller means that the signals in the control device are affected by these electromagnetic interference signals. To produce electromagnetic compatibility for these two arrangements, the controllers have electrically connected capacitors which compensate for the interference signals.
In operation, the power electronics and the capacitors both produce a high heat loss which is dissipated to the surroundings via the housing.
This requires comprehensive designs for the housing in the form of cooling ribs to dissipate the heat produced quickly.
SUMMARY OF THE INVENTION
The invention is based on the object of providing an electronic device which is easy to manufacture and in which the heat produced by the electronic circuits does not affect the operation of the electronic circuits further.
The invention achieves the object in that the capacitor unit, which is provided to have a large surface area, is thermally connected to a first housing part, and the electronics unit is thermally connected to a second housing part.
The advantage of the invention is that the two components, which produce different levels of heat loss, are thermally decoupled. The configuration of the heat sink for each housing part can be matched to the specific circumstances.
In one refinement, the modular capacitor unit can be fitted into a connector unit which is of modular form and is mounted on the first housing part. The modular configuration of both the capacitor unit and the connector unit enables simple installation in the housing. For the capacitor unit, separate mounting means are dispensed with completely. It is locked on the housing with the connector unit.
To ensure that the capacitor unit is located robustly, the capacitor unit is prestressed against the first housing part by a spring element supported on the second housing part. In addition, this arrangement makes the capacitor unit insensitive to vehicle vibrations. Vehicle movements have no effect on the electrical connections of the capacitor unit. This means that short circuits are reliably prevented.
In another refinement, the connector unit and the capacitor unit are mechanically mounted independently of one another on the second housing part. This arrangement ensures that the capacitor unit is located so as to withstand vibrations, so that there is no need for additional measures to ensure robustness.
Advantageously, a thermally conductive adhesive layer is arranged between the capacitor unit and the first housing part. This thermally conductive adhesive layer not only transfers the heat produced by the capacitor unit to the first housing part but additionally compensates for the large tolerances of the capacitor inside the housing.
In one refinement, contact elements of the connector unit, which are of integral design and are guided outward, run below the capacitor unit and can be connected to the electrical connections of the electronics unit at a bonding surface which faces the interior of the housing. Particularly if the contact elements are designed as a sheet metal casting, such a space-saving shape is easy to produce.
The electronics unit rests flat on the second housing part, which is of plate-like form, for the purpose of thermal coupling. This achieves optimum heat exchange between the electronics and the housing part.
The two housing parts have a rib-like outer surface which is formed with different thicknesses. The arrangement of the capacitor unit and the electronics unit in different housing parts enables a cooling-rib variation which can thus be optimally matched to the amount of heat to be dissipated which is produced by the respective device.
In one refinement, the first housing part is provided to hold the individual capacitor elements forming the capacitor unit with a form fit. In this arrangement, the capacitor elements are placed directly onto the housing part, which produces direct thermal contact.
Particularly when commercially available capacitor cells are used, the inner surface of the first housing part has semicircular depressions corresponding to the outer contour of the capacitor elements.
In this case, the capacitor elements form two regions which are isolated by baffle plates connected to different electrical potentials. This arrangement eliminates the need for extensive line connections for the capacitors.
In this arrangement, the baffle plates are approximately L-shaped, which enables space-saving installation.
In order to provide an electronic device which is as small as possible, the first housing part rests on a hybrid frame which is connected to the second housing part, which bears the electronics unit, with a form fit.


REFERENCES:
patent: 4292665 (1981-09-01), Hersom et al.
patent: 4639834 (1987-01-01), Mayer
patent: 5016139 (1991-05-01), Stopa et al.
patent: 5097404 (1992-03-01), Layh
patent: 5835350 (1998-11-01), Stevens
patent: 5912514 (1999-06-01), Stendardo et al.
patent: 5926659 (1999-07-01), Matsui
patent: 9002596 (1990-05-01), None
patent: 4118398 (1992-12-01), None
patent: 4333387 (1994-03-01), None

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