GB1587856A - Electronic control devices especially for travel speed regulators in motor vehicles - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ELECTRONIC CONTROL DEVICES, ESPECIALLY FOR TRAVEL SPEED REGULATORS IN MOTOR VEHICLES (71) We, ROBERT BOSCH GMBH, a German company, of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to electronic control devices, especially for travel speed regulators in motor vehicles.

One known electronic control device has a printed circuit board accommodated in a housing and carries electronic circuits, components for control electronics and a power stage, and a contact strip. In such a control device, a plate heat sink having a U-shaped cross-section is screwed onto the housing of the control device. Two power transistors are disposed one beside the other on the plate heat sink. One printed circuit board is mounted on the plate heat sink by means of spacer screws and a second printed circuit board is screwed onto the U-shaped arms of the plate heat sink. In addition, an electronic control device has been proposed which has a plate heat sink having an L-shaped cross-section. The plate heat sink is mounted on the housing by means of an arm. A tempereature monitoring device is also screwed onto this arm. The other arm, however, carries the power transistors. A disadvantage with such known control devices is that, because the plate heat sink is designed according to the actual installation circumstances, the power transistors cannot be disposed at an equal distance from the temperature monitoring device.

According to the present invention there is provided an electronic control device comprising components for control electronics, a power stage. a connection strip a printed circuit board adapted to be accommodated in a housing and carrying electronic circuits interconnecting said components for control electronics, said power stage and said connector strip, a plate heat sink mounted on the printed circuit board and spaced at a distance therefrom, and a temperature monitoring device mounted on the plate heat sink, components of the power stage being disposed on the heat sink substantially concentrically about the monitoring device with their connecting leads connected to associated connections on the printed circuit board.

In a control device embodying the present invention the components for the power stage, which act as heat sources, can be disposed at equal distances from the temperature monitoring device and, in a spacesaving manner, the plate heat sink is mounted on the printed circuit board, the air gap between the printed circuit board and plate heat sink ensuring that soldered joints on the connecting leads of the components are highly resistant to temperature changes.

The invention will be further described by way of example with reference to the accompanying drawings illustrating one embodiment of the invention and in which: Figure 1 is a partial, longitudinal section through a control device embodying the present invention, and Figure 2 is a plan view of the portion of the printed circuit board, with its components, shown in Figure 1.

An electronic control device embodying the present invention has a housing 1, wherein a printed circuit board 2 is disposed. A connector strip in the form of plug board 3 is secured to the printed circuit board 2. The plug board 3 carries plugs 4, to which contact lugs 5 are connected. The contact lugs 5 have bent ends which are disposed in the printed circuit board 2 and are connected to conductor paths of the printed circuit board 2 which are not shown.

A plate heat sink 6, made of aluminium or another light metal has a substantially square shape with three mounting lugs 7.

Disposed in the centre of the plate heat sink 6 is a bimetal switch 8 which is used as a temperature monitoring device. The bimetal switch 8 is provided with two connecting leads 9 and 10. Electrically insulated from the plate heat sink and disposed concentrically about the bimetal switch 8 on the plate heat sink 6 and at an equal distance away from each other are four transistors 11. This arrangement ensures that the temperature of the transistors 11 is monitored uniformly.

The transistors 11 each have two electrical connecting leads 12 which extend through holes in the plate heat sink 6 and through associated holes in the printed circuit board 2. An additional electrical connecting lead 13, the collector lead, is welded onto the mounting plate 14 of each of the transistors 11 as an angularly bent wire. Each connecting lead 13 extends laterally beyond an edge of the plate heat sink 6 and also protrudes through an associated bore in the printed circuit board 2 into the region in which all the connecting leads on the underneath side of the printed circuit board 2 are soldered.

By means of mechanical soldering, all the connecting leads are connected in an electrically conductive manner to the associated conductor paths, which are not shown, on the printed circuit board 2. The use of the electrical connecting leads 13 enables the plate heat sink 6 to be kept sufficiently small when there is little room in the housing 1 and enables space to be kept on the printed circuit board 2 for the arrangement of further components.

The plate heat sink 6 is provided with hollow spacer rivets 15 on the mounting lugs 7. The hollow rivets 15 abut one surface of the printed circuit board 2 and their free ends are riveted to the printed circuit board 2. The hollow rivets 15 serve simultaneously as spacers and mounting members for the plate heat sink 6 on the printed circuit board 2. The air gap between the printed circuit board 2 and the plate heat sink 6, which carries the transistors 11 which emit dissipated heat, ensures that the soldered joints are highly resistant to temperature changes.

The printed circuit board 2, which is provided with all the components and carries the electrical circuit, can easily be examined and adjusted when it is thus assembled. It is then pushed into the housing 1, which is sealed with a cover 16 through which the plugs 4 protrude from the housing 1.

WHAT WE CLAIM IS: 1. An electronic control device, comprising components for control electronics, a power stage, a connector strip a printed circuit board adapted to be accommodated in a housing and carrying electronic circuits interconnecting said components for control electronics, said a power stage and said connector strip, a plate heat sink mounted on the printed circuit board and spaced at a distance therefrom, and a temperature monitoring device mounted on the plate heat sink, components of the power stage being disposed on the heat sink substantially concentrically about the monitoring device with their connecting leads connected to associated connections on the printed circuit board.

2. A control device as claimed in claim 1, in which the plate heat sink is made of a light metal.

3. A control device as claimed in claim 1 or 2, in which the temperature monitoring device is a bimetal switch which is mounted on the plate heat sink.

4. A control device as claimed in any of claims 1 to 3, in which the plate heat sink is mounted on the printed circuit board by spacer rivets.

5. A control device as claimed in any of claims 1 to 4, in which the components for the power stage are disposed on the plate heat sink in an electrically insulated man ner and each has a third connecting lead which is in the form of wire mounted on the housing of the respective component.

6. A control device as claimed in claim 5, in which each third connecting lead extends beyond an edge of the plate heat sink and is angularly bent to connect with the printed circuit board.

7. An electronic control device constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. another light metal has a substantially square shape with three mounting lugs 7. Disposed in the centre of the plate heat sink 6 is a bimetal switch 8 which is used as a temperature monitoring device. The bimetal switch 8 is provided with two connecting leads 9 and 10. Electrically insulated from the plate heat sink and disposed concentrically about the bimetal switch 8 on the plate heat sink 6 and at an equal distance away from each other are four transistors 11. This arrangement ensures that the temperature of the transistors 11 is monitored uniformly. The transistors 11 each have two electrical connecting leads 12 which extend through holes in the plate heat sink 6 and through associated holes in the printed circuit board 2. An additional electrical connecting lead 13, the collector lead, is welded onto the mounting plate 14 of each of the transistors 11 as an angularly bent wire. Each connecting lead 13 extends laterally beyond an edge of the plate heat sink 6 and also protrudes through an associated bore in the printed circuit board 2 into the region in which all the connecting leads on the underneath side of the printed circuit board 2 are soldered. By means of mechanical soldering, all the connecting leads are connected in an electrically conductive manner to the associated conductor paths, which are not shown, on the printed circuit board 2. The use of the electrical connecting leads 13 enables the plate heat sink 6 to be kept sufficiently small when there is little room in the housing 1 and enables space to be kept on the printed circuit board 2 for the arrangement of further components. The plate heat sink 6 is provided with hollow spacer rivets 15 on the mounting lugs 7. The hollow rivets 15 abut one surface of the printed circuit board 2 and their free ends are riveted to the printed circuit board 2. The hollow rivets 15 serve simultaneously as spacers and mounting members for the plate heat sink 6 on the printed circuit board 2. The air gap between the printed circuit board 2 and the plate heat sink 6, which carries the transistors 11 which emit dissipated heat, ensures that the soldered joints are highly resistant to temperature changes. The printed circuit board 2, which is provided with all the components and carries the electrical circuit, can easily be examined and adjusted when it is thus assembled. It is then pushed into the housing 1, which is sealed with a cover 16 through which the plugs 4 protrude from the housing 1. WHAT WE CLAIM IS:

1. An electronic control device, comprising components for control electronics, a power stage, a connector strip a printed circuit board adapted to be accommodated in a housing and carrying electronic circuits interconnecting said components for control electronics, said a power stage and said connector strip, a plate heat sink mounted on the printed circuit board and spaced at a distance therefrom, and a temperature monitoring device mounted on the plate heat sink, components of the power stage being disposed on the heat sink substantially concentrically about the monitoring device with their connecting leads connected to associated connections on the printed circuit board.

2. A control device as claimed in claim 1, in which the plate heat sink is made of a light metal.

3. A control device as claimed in claim 1 or 2, in which the temperature monitoring device is a bimetal switch which is mounted on the plate heat sink.

4. A control device as claimed in any of claims 1 to 3, in which the plate heat sink is mounted on the printed circuit board by spacer rivets.

5. A control device as claimed in any of claims 1 to 4, in which the components for the power stage are disposed on the plate heat sink in an electrically insulated man ner and each has a third connecting lead which is in the form of wire mounted on the housing of the respective component.

6. A control device as claimed in claim 5, in which each third connecting lead extends beyond an edge of the plate heat sink and is angularly bent to connect with the printed circuit board.

7. An electronic control device constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.