AU2005242151A1

AU2005242151A1 - Cooling arrangement for an electric control unit

Info

Publication number: AU2005242151A1
Application number: AU2005242151A
Authority: AU
Inventors: Andre Lischeck; Udo Schulz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-03-31
Filing date: 2005-12-07
Publication date: 2006-10-19
Also published as: EP1708264A3; EP1708264A2; DE102005015718A1

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

TO BE COMPLETED BY APPLICANT Name of Applicant: Actual Inventors: Address for Service: Invention Title: ROBERT BOSCH GMBH Andre Lischeck; and Udo Schulz CALLINAN LAWRIE, 711 High Street, Kew, Victoria 3101, Australia COOLING ARRANGEMENT FOR AN ELECTRIC CONTROL

UNIT

The following statement is a full description of this invention, including the best method of performing it known to us:- 07/12/05,eh15375.cov,1 -2- COOLING ARRANGEMENT FOR AN ELECTRIC CONTROL UNIT Prior Art The invention relates to a cooling-arrangement for an electric control unit.

In Prior-art cooling-arrangements for electric control units use liquid cooling circuits whose coolant is the fuel for the internal combustion engine controlled by the control unit. The fuel line between the fuel tank and the internal combustion engine is used as the coolant conduit, and runs on or through the control unit's housing, for 10 heat transfer and absorption. Such arrangements are already known in the art, from their use in motor vehicles with Diesel engines, in which the transmission of heat from the control unit to the fuel is of no great consequence. With Otto engines, however, this possibility does not exist, because the fuel could be heated to an impermissible degree by the energy dissipated from the control unit being cooled.

Therefore, with Otto engines, the cooling-water circuit is used for cooling the control unit. A drawback with this solution is that, due to the coolant, the control unit is continually subjected to a large temperature differential. This can lead to increased expenses for making the control unit resistant to thermal shock.

Summary of the Invention According to the present invention there is provided a cooling-arrangement for an electric conitrol unit, said cooling-arrangement including: a first coolantcircuit, a second coolant-circuit, whereto coolant can be supplied from the first coolant-circuit, and wherefrom coolant can be discharged to the first coolant-circuit, and a coolant conducting heat-exchanger, arranged on the control unit and forming part of the second coolant-circuit, wherein said first coolant-circuit is part of the coolant-circuit of an internal combustion engine, and wherein said second coolantcircuit can be cut in by means of a diverter valve.

07/12/05,eh15375.spc,2 c Advantages of the Invention The inventive cooling-arrangement for an electric control unit with the features of the principal claim is advantageous in that it provides a simple, upstream, diverter arrangement whereby the flow of coolant can be diverted to the control unit t when and only when required, and whereby, on the other hand, overheating of C the banked up flow of cooling-water can be prevented.

C Advantageous further developments of the cooling-arrangement in the principal claim are possible, through the measures given in the dependent claims.

cI 10to If the diverter valve is designed as an electrically operable valve which, in addition, will switch temperature-responsively, then this results in a coolingarrangement whose diverter valve can be controlled very accurately, and with which due to the temperature-dependent valve actuation it is even possible, if desired, to use the temperature of a particular component inside the control unit the component that heats up the most or the quickest) for cutting-in the coolant-circuit.

If a temperature-sensor is provided, then its status, and hence the corresponding temperature, can be determined e.g. by means of a computer. This makes it possible to integrate the temperature-sensing into the central processing unit (CPU). This will eliminate the need to process the temperature-signal in another, external unit, and will thus lead to a structure that is compact in design and pretty much trouble-free.

In a further development of the invention, the diverter valve is a self-acting valve. This is advantageous in that there is no need for an electronically analyzed temperature-sensor whose status needs to be processed by a CPU or other computer.

The result is, therefore, a particularly simple cooling-arrangement.

A very simple embodiment of a self-acting diverter valve is one in which a liquid-conducting element, which is provided in the diverter valve and which implements the valve function, is switched-over by a bistable spring-element. A thermal bimetallic snap-action element has proved particularly suitable for this purpose, and is a specific example of an embodiment of a bistable spring-element.

07/12/05,eh 15375.spc,3

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SDrawings The drawings show an example of an embodiment of a cooling-arrangement according to the invention. In the drawings: t Fig. 1 is a cooling-arrangement for an electric control unit with a diverter N valve, in which the coolant-circuit of the control unit is connected to the coolant- C circuit of an internal combustion engine;

V)

Fig. 2 is an electrically operable diverter valve; ci 10 Fig. 3 is a control unit with a temperature-sensor and a computer; and Fig. 4 is a self-acting diverter valve with a bistable spring-element.

Description Fig. 1 shows a cooling-arrangement 10 for an electric control unit 13. This cooling-arrangement 10 also includes an internal combustion engine 16 and its water-jacket 19. The cooling-arrangement 10 has a first coolant-circuit 22, which consists of the water-jacket 19, a section of tubing 25 between the water-jacket 19 and the inlet 28 to a diverter valve 31, the diverter valve 31, an outlet 34 from the diverter valve 31, and the section of tubing 37 connecting the outlet 34 with the water-jacket 19 via a cooler 35. There is also a second coolant-circuit 40, which is not a true circuit, but only an extension or parallel branch of the first coolant-circuit 22, leading away from the latter and back to it. The second coolant-circuit 40 begins at a first outlet 43 of the diverter valve 31, wherefrom the coolant runs through a connecting-tube 46, to the control unit 13, where it flows through a heat-exchanger (not show in Fig. and then leaves the control unit 13 and passes into another connecting-tube 49, and finally into tubing-section 37. The second coolant-circuit can be cut in by means of the diverter valve 31 whenever necessary, to cool the control unit 13.

Fig. 1 thus shows a cooling-arrangement 10 for an electric control unit 13, with a first coolant-circuit 22, and with a second coolant-circuit 40, to which coolant (52) can be supplied from the first coolant-circuit and from which coolant can 07/12/05,eh 5375.spc,4

O

rbe discharged to the first coolant-circuit On the control unit 13, there is arranged a heat-exchanger, which conducts the coolant 52 and forms part of the second coolant-circuit 40. The first coolant-circuit 22 is part of the coolant-circuit of an internal combustion engine 16. The second coolant-circuit 40 can be cut in by means of a diverter valve 31.

tt Fig. 2 is a diagrammatic representation of the diverter valve 31. The diverter Svalve 31 has the already-mentioned inlet 28, first outlet 43, and second outlet 34. The Sdiverter valve 31 also has electric terminals 55 through which the diverter valve 31 can be actuated electrically. The electric terminals 55 lead to an electric control unit N l0 (not shown), enabling the admitted coolant 52 to be redirected in the diverter valve 31. The power supply to the electric terminals 55 is e.g. temperature-dependant, thus making the switching-over of the diverter valve 31 effectively temperaturedependant as well.

Fig. 3 shows the control unit 13 in longitudinal section. The control unit 13 has a housing 58, which surrounds a printed circuit board 61, on which there is arranged e.g. a temperature-sensitive processor 64, on which a temperature-sensor 67 is arranged. A computer 70 on the printed circuit board 61 processes the signal from the temperature-sensor 67, and controls the diverter valve 31 and the setting thereof, doing so over electrical connections (not shown) that are connected to the electric terminals 55 of the diverter valve 31. In Fig. 3, there is a heat-exchanger 73 beneath the printed circuit board 61. This heat-exchanger 73 has both an inlet 75 and an outlet 78. The inlet 75 is connected to connecting-tube 46, and the outlet 78 is connected to connecting-tube 49. Thus, Fig. 3 shows that the cooling-arrangement has a temperature-sensor 67, whose status can be determined by a computer 70. The computer 70 can also be a central processing unit (CPU) 64 belonging to the control unit 13.

The heat-exchanger 73 could also be arranged above the printed circuit board 61 or could e.g. be integrated in the housing 58.

Fig. 4 shows the diverter valve 31 as a self-acting valve. The diverter valve 31 has a bistable spring-element 81, which switches the valve 31. The spring element can be a thermal bimetallic snap-action element that can be actuated thermally. This means that the temperature of the coolant 52 flowing e.g. between the inlet 28 and 07/I 2/05,eh 15375.spc,5 -6c the second outlet 34 will trigger the bistable spring-element 81 to switch over the

U

Sflow from the inlet 28 to the first outlet 43.

An advantage of the invention is that the control unit 13 only has coolingwater flowing through it once a certain temperature is reached in the control unit 13.

As a result, the temperature differentials to which the control unit 13 is subjected are Ir minimized. In an arrangement without a diverter valve 31, it would happen that e.g.

N, in the partial-load range and/or with low outside temperatures i.e. with the control unit 13 producing little dissipation-heat and requiring no liquid cooling the control unit 13 would be additionally heated by the coolant 52. Due to the bypass I 10 section between the second outlet 34 and the confluence of the two coolant-circuits and 22, no heat builds up before the heat-exchanger 73 of the control unit 13, and no large pressure-fluctuations occur in the second coolant-circuit 40. If the diverter valve 31 is electrically actuated, the temperature of the control unit 13 can be measured by means of the temperature-sensor 67 and can be acquired by the CPU 64 or computer 70. When a threshold value is exceeded, the diverter valve 31 will then be actuated electrically. The advantage of this is that the design can remain unchanged for different control unit applications, and can be adapted to different installation situations and/or different control unit dissipation situations through software alone. The software is responsible for deciding whether the diverter valve 31 is to be actuated or not.

If a self-acting diverter valve 31 with a thermal bimetallic snap-action element 81 is used, then this has the advantage compared with conventional bimetallic actuating elements of executing a large opening stroke (snapping stroke) on reaching a "snapping temperature". This ensures that the control unit 13 is not overheated on reaching a temperature limit. This actuating element and hence the diverter valve 31 is to be arranged directly on the control unit's housing 58 so that it experiences any increase in the temperature of the control unit 13.

07/12/05,eh 15375.spc,6

Claims

1. A cooling-arrangement for an electric control unit, said cooling- Sarrangement including: a first coolant-circuit, a second coolant-circuit, whereto coolant can be supplied from the first Scoolant-circuit, and wherefrom coolant can be discharged to the first coolant-circuit, and N, a coolant conducting heat-exchanger, arranged on the control unit and V) forming part of the second coolant-circuit, N 10 wherein said first coolant-circuit is part of the coolant-circuit of an internal combustion engine, and wherein said second coolant-circuit can be cut in by means of a diverter valve.

2. The cooling-arrangement as claimed in claim 1, wherein the diverter valve is electrically-operable.

3. The cooling-arrangement as claimed in claim 2, wherein the diverter valve will switch over temperature-responsively.

4. The cooling-arrangement as claimed in claim 2 or 3, wherein a temperature-sensor is provided, whose status is determinable by a computer.

The cooling-arrangement as claimed in claim 4, wherein the computer is a CPU of the control unit.

6. The cooling-arrangement as claimed in claim 1, wherein the diverter valve is a self-acting valve.

7. The cooling-arrangement as claimed in claim 6, wherein a bistable spring-element switches the valve. 07/12105,eh 5375.spc,7 c

8. The cooling-arrangement as claimed in claim 7, wherein the spring- Selement is a thermal bimetallic snap-action element.

9. The cooling arrangement, substantially as hereinbefore described with reference to the accompanying drawings. 0 Dated this 7 t h day of December, 2005 rN ROBERT BOSCH GMBH By Their Patent Attorneys CALLINAN LAWRIE AWI- 07/12/05,eh15375.spc,8