WO2009037075A1

WO2009037075A1 - Electrical device for use in strongly oscillating environments, and attenuator

Info

Publication number: WO2009037075A1
Application number: PCT/EP2008/061195
Authority: WO
Inventors: Andre Carvalho; Gernot Schuster
Original assignee: Continental Automotive Gmbh
Priority date: 2007-09-14
Filing date: 2008-08-27
Publication date: 2009-03-26
Also published as: DE102007043886A1

Abstract

The invention relates to an electrical device (1), particularly a controller for a motor vehicle, for use in strongly oscillating environments. The invention provides an electronic module (10) that is connected to a housing (20) via a heat conductor for heat dissipation, and an attenuator that at least reduces the transmission of oscillations to the electronic module (10), wherein the attenuator is formed by the heat conductor, which is embodied as a thermally conductive paste (14, 15).

Description

description

Electrical device for use in high-vibration environments and attenuator

The invention relates to an electrical device, in particular a control device for a motor vehicle, for use in strongly oscillating environments with an electronic module. The invention further relates to an attenuator insbesonde- re for a control device in a motor vehicle, for Reduzie ^¬ tion of the transmission of vibrations to a component.

In engine and transmission control units, which are also referred to as "Power Train Control Units PCU" is often egg ne mounting directly on the engine or of a concern ^¬ the motor vehicle is provided on the transmission. This is a result of the effort to individual modules completely pre-assemble to and the modules can be subjected to a functional test before being installed, resulting in higher levels of damage as a result of the direct mounting of the control units on the engine or gearbox

Vibration loads of the electronic modules contained in the respective control unit.

Since the vibrations applied to the electronic module may affect the reliability of the electronic module over time, various solutions exist to keep the vibrations away from the electronic module in the electrical device.

So external damper made of a rubber, for example, ver ^¬ applies to dampen the vibrations which are transmitted to the electronic Mo ^¬ dul. The dampers are for this purpose introduced into fastening tabs of a housing of the electrical device, so that already act on the housing of the electrical device lower vibrations. In this variant, the electronic module can be rigidly connected to the housing of the electrical device. A disadvantage of this variant Ante is that the dampers made of rubber lose their mechanical properties over time, which worsens the damping of the vibrations. The mechanical properties affecting factors are constant mechanical and thermal loads and Korro ^¬ sion in contact with oils, lubricants, salt water, etc.

Alternatively, it is known to arrange rubber sleeves inside the electrical appliance which press the electronic module against a booklet in the housing. The press-in area bean ^¬ sprucht relatively much space, so that valuable area of the electronic module for electrical functions is lost.

Further, for vibration damping, the electronic module provided in the housing of the electrical device may be completely enclosed with a potting compound, e.g. a gel, to be shed. The disadvantage of this is the cost and high weight of the electrical device.

In order to dissipate heat from the electronic module via the housing of the electrical device, it is also common to provide a heat conductor with a good thermal conductivity.

It is an object of the present invention to provide an electrical device in which the vibration damping can be realized in a simpler and more cost-effective manner. It is a further object of the present invention to provide a damping member that enables the vibration damping of a component in a simple and cost-effective manner.

These objects are achieved by the features of the independent claims. Advantageous embodiments will be apparent from the dependent claims. An inventive electrical device, in particular a control device for a motor vehicle, for use in strongly oscillating environments comprises an electronic module which is connected via a heat conductor with a housing of the electrical device for heat dissipation. The device further comprises an attenuator which at least reduces the transmission of vibrations to the electronic module. According to the invention, the attenuator is formed by the heat conductor formed as a thermally conductive paste.

The invention is based on the finding that the pasty material of the heat conductor has good damping properties in addition to the desired thermal conductivity. It is therefore intended to use the thermally conductive paste targeted as an attenuator in order to counteract the Schwingungsbe ^¬ loads the electronic module in the electrical device. As a result, additional, provided externally or internally in the electronic device mechanical damper, such as rubber buffer and the like, are completely eliminated. This makes it possible to simplify considerably the design on ^¬ construction of the electrical device, thus it is less expensive to produce. Another advantage is that an electrical device according to the invention has a smaller volume compared to conventional electrical devices having attenuators and can thus be installed in a space-saving manner.

According to the invention, a pasty, thermally conductive material is thus provided for the damping of vibrations.

According to an expedient embodiment, the housing has one or more contact surfaces on which or which the electronic module rests flat, wherein the thermally conductive paste is provided between the one or more support surfaces and the electronic module. In order to take over the damping function optimally, it is further provided, the thermally conductive paste substantially to provide full area between the one or more bearing surfaces and the electronic module.

The total area and / or the arrangement of the one or more contact surfaces is measured in a variant according to a power loss of the electronic module. According to this variant, the heat balance of the electric Ge ^¬ Raets is primarily optimized to ensure that provided in the electro ^¬ African module electrical components by overheating Ü can not be damaged. In an alternative or additional embodiment, the total area and / or arrangement of the one or more bearing surfaces is measured according to a vibration damping of the electronic module to be achieved. Since the vibration behavior can be influenced by the quantity or area of the thermally conductive paste, the vibration behavior or the damping to be achieved can be adjusted in a targeted manner by designing the one or more bearing surfaces. The total ^¬ surface and / or the arrangement of one or more supporting surfaces can be ^¬ telt easily by tests ermit. With known mechanical properties of the thermally conductive paste as well as a calculation of the total area and / or arrangement of the one or more contact surfaces is possible in order to achieve the desired result.

In one embodiment of the invention, the electronic module comprises a printed circuit board on which a plurality of elekt ^¬ ronic components is applied, wherein the thermally conductive paste between the circuit board and the housing is arranged. Here, the circuit board of the electronic ^¬'s modulus may rest on support Domen the one or more bearing surfaces and be connected to them via respective fastening means.

An additional vibration damping is effected in that at least one electronic component, in particular with high power loss, via the thermally conductive passport te is connected to the housing. This allows ^¬ example, a vibration damping in multiple locations and, optionally, opposite sides of the electronic module can be effected, whereby the vibration damping loan without additional space requirements can be improved. In addition, this results in the advantage that at the same loss heat ^¬ can be dissipated.

The thermally conductive paste expediently has a thickness of between 0.1 and 0.3 mm, in particular 0.2 mm. The distance can for example be determined by the support domes have a corresponding distance from the surface of the bearing surfaces.

In a further embodiment, the housing is made of a rigid material, in particular a metal.

Of the invention is not only an electrical device into ^¬ particular a control device for a motor vehicle, comprising, but also in general form an attenuator USAGE in particular for a control device in a motor vehicle is ^¬ det. The damping member is formed to reduce the Übertra ^¬ supply of vibrations to a component through a heat conductor in the form of a paste-like, particularly thermally conductive material.

The invention will be explained in more detail with reference to FIGS. Show it:

1 shows a part of an electrical device according to the invention in a cross-sectional view,

2 shows a cross-sectional view through a further electrical device, which illustrates the principle of the invention as well as FIG Fig. 3 is a continuous projecting from a vibration analysis slide ^¬ grams, which represents the frequency response of a damped ge ^¬ genüber an undamped device according to the invention.

Fig. 1 shows a cross-sectional view of a portion of an electrical device according to the invention 1. The electrical device may, for example, as a motor control unit, Getriebesteu ^¬ ergerät or a control unit for controlling personnel nenschutzmitteln be formed, which in a strongly vibrating / oscillating component, such as an engine or transmission of a motor vehicle is attached. The electrical device 1 comprises an electronic module 10, which is arranged in a housing 20, for example made of a metal, and connected thereto via a fastening means 25. The Fixed To ^¬ restriction means 25 may for example comprise a screw or a plug connection.

The electronic module 10 comprises a printed circuit board 11, on which in the exemplary embodiment a plurality of electronic components 12 is arranged on both main sides. The individual components 12 can over on the circuit board

11 provided interconnects and / or vias electrically connected to each other.

The circuit board 11 is adjacent to a portion on an on ^¬ bearing surface 21 of the housing twentieth From Fig. 1 here is not apparent that the circuit board rests on a Aufla ^¬ gedom 22 11, which slightly protrudes over the supporting surface 21. The circuit board 11 is fastened in the region of the open position ^¬ tower 22 to the housing 20 via the fastening means 25th In the process, in the area of the bearing surface 21, a gap is created between the bearing surface 21 and the printed circuit board 11, which is essentially filled over its entire area with a thermally conductive paste 14. The thermally conductive paste 14 serves on the one hand, in the electronic components

12 dissipated heat loss via the housing 20 animals. In order to effect a better cooling of the electronic components 12, the housing 20 is provided with a plurality of cooling fins 24, which extend substantially perpendicularly away from the housing 20.

The ge ^¬ formed between the circuit board 11 and the support surface 21 gap is advantageously between 0.1 mm and 0.3 mm, preferably about 0.2 mm. The thickness of the gap ent ^¬ speaks in this case also the thickness of the introduced therein thermally conductive paste. The thermally conductive paste can be dispensed onto the support surface 21 of the housing 20, for example, but this need not be done over the entire surface. By applying the circuit board 11 of the electronic ^¬'s modulus and pressing against the support surfaces 21, the thermally conductive paste 14 is crimped, so that the desired ge ^¬, is essentially full-surface coverage of the cultivation area ^¬ 21st

In addition to the heat dissipation, the thermally conductive paste 14 also assumes the task of damping the vibrations transmitted to the electronic module 10, which occur when the electrical device 1 is mounted via its housing 20 on a mounting ^surface exposed to vibration. Already provided in said layer thickness thermally conductive paste 14 is sufficient to reduce the transmitted to the electronic module 10 vibrations to a desired level to reduce ^¬ ren.

The vibrations transmitted to the electronic module 10 are dependent not only on the layer thickness of the thermally conductive paste 14, but also on the size of the support surface 21 or the arrangement of a plurality of bearing surfaces. Depending on the configuration of the electrical device 1 and the circumstances at the place of attachment, the size of the support surface 21 and thus the size / arrangement of the available surface for vibration damping can be varied. In the case provided in the Fig. 1 embodiment, a device 13 with a large loss Leis ^¬ tung is disposed on the circuit board 11. The component 13 may be formed, for example, by a capacitor or a coil. The component 13 is adjacent to an arcuate housing section 23, where a is formed approximately uniformly thicker gap ^¬ in between the housing portion 23 and the component 13, wel ^¬ cher is filled with thermally conductive paste 15 °. As a result, on the one hand, an optimized loss of heat dissipation from the component 13 to the housing 20 is made possible. Furthermore, the electronic module 10 is provided with a further damping ^¬ membered.

The electronic module 10 can, as shown in the figure, by a cover 27, e.g. made of a plastic or a metal, be closed.

In addition to the thermally conductive paste 14, 15 provided as an attenuator, the electrical appliance according to the invention furthermore requires no further mechanical damping ^{elements in} order to minimize the vibrations transmitted to the electronic module to a desired level. This simplifies the structural design of the electrical Ge ^¬ device. In addition, the electrical device 1 can be produced inexpensively and in a space-saving manner.

Fig. 2 shows a schematic representation of the principle underlying the invention for damping vibrations in a simplified manner. Here, an electrical device 1 is shown in a cross-sectional view. On the circuit board 11 of the electronic module 10, a number of electronic components 12 is applied. These can be applied with or without a housing in a known manner to the conductor ^¬ plate 11 and electrically connected to each other. An electrical connection may be via provided on the printed circuit board 11 conductive traces (not shown) Herge ^¬ represents. The electronic module 10 is equipped with its terplatte 11 connected to the housing 20. Between the Lei ^¬ terplatte 11 and the housing 20, more precisely bearing surfaces 21 of the housing 20, thermally conductive paste 14 is ^{¬ introduced} , on the one hand for the removal of heat from the components 12 to the housing 20 and on the other hand for the Dämp ^¬ Fung transmitted to the electronic module 10 vibra ^¬ tions provides. The electronic module 10 is further protected by ei ^¬ nen cover 27 from external influences, wherein the lid 27 is connected to the housing 20. The mechanical fastening of the electronic module 10 to the housing is not shown.

Fig. 3 shows a diagram in which the acceleration a is plotted against the frequency f. The gekennzeich- with Kl designated curve shows the frequency response of an electric Ge ^¬ Raets, wherein the electronic module is not connected via a ther ^¬ mixed conductive paste with the housing. It can be clearly seen that at a frequency f _n ~ 180 Hz, a first natural frequency of the undamped electrical device is present, with an acceleration of just under 2000 m / s ^{2 is} achieved. The curve marked K2 shows the frequency ^{profile of} an electrical device according to the invention with the thermally conductive paste as attenuator. It is clear that a first natural frequency f _d occurs at about 360 Hz, the acceleration to about 180 m / s ² ver ^¬ is Ringert. The displacement of the first natural frequency of the damped electrical device is determined by the modulus of elasticity (modulus of elasticity) of the thermally conductive paste. The damping, ie the decrease of the acceleration maximum at the first natural frequency is determined by the damping constant ς.

As can easily be seen from the diagram, the thermal conductive paste arranged between the electronic module and the housing of the electrical device achieves a significant vibration damping, which is the additional Provision of further mechanical attenuators dispensable.

So far, thermally conductive pastes are only used to ensure a thermal connection of the electronic building ^¬ elements of the electrical device. The targeted use of the thermal paste also vibrations can be damped.

Claims

claims

1. Electrical device (1), in particular control device for a motor vehicle, for use in strongly oscillating environments with an electronic module (10) which is connected via a heat conductor to a housing (20) for heat dissipation and with an attenuator, the transmission of oscillations ^¬ conditions to the electronic module (10) is at least reduced, and the damping member as formed by the thermally conductive paste (14, 15) of heat conductor is formed.

2. Apparatus according to claim 1, wherein the housing (20) has one or more bearing surfaces (21) on which or which the electronic module (10) rests flat, wherein the thermally conductive paste (14, 15) between the one or the plurality of bearing surfaces (21) and the electronic module (10) is provided.

3. Apparatus according to claim 2, wherein the thermally conductive paste (14, 15) is provided substantially over the entire surface between the one or more bearing surfaces (21) and the electronic module (10).

4. Apparatus according to claim 2 or 3, wherein the total area and / or arrangement of the one or more bearing surfaces (21) is measured according to a power loss of the electronic module (10).

5. Apparatus according to claim 2, 3 or 4, wherein the total area and / or arrangement of the one or more bearing surfaces (21) measures according to a vibration damping to be achieved of the electronic module (10).

6. Device according to one of the preceding claims, wherein the electronic module (10) comprises a printed circuit board (11) on which a plurality of electronic components (12) is applied, wherein the thermally conductive paste (14, 15) between the circuit board (11) and the housing (20) angeord ^¬ net is.

7. Apparatus according to claim 6 in conjunction with any one of claims 2 to 5, wherein the circuit board (11) of the electronic module (10) rests on support domes (22) of the one or more support surfaces (21) and with these over respective Fastener (25) is mechanically connected.

8. Apparatus according to claim 6 or 7, wherein at least one elekt ^¬ ronic component (12), in particular with high loss ^¬ power, via the thermally conductive paste (14, 15) is connected to the housing (20).

9. Device according to one of the preceding claims, wherein the thermally conductive paste (14, 15) has a thickness between 0.1 mm and 0.3 mm, in particular 0.2 mm.

10. Device according to one of the preceding claims, wherein the housing (20) made of a rigid material, in particular a

Metal, is formed.

11. attenuator, in particular for a control unit in a motor vehicle, to reduce the transmission of vibrations gene on a component, wherein the attenuator is formed by a heat conductor in the form of a pasty, in particular thermally conductive material.

12. Use of a paste-like, thermally conductive material for the damping of vibrations.