GB2343164A

GB2343164A - Cooling an electronic control unit in a vehicle

Info

Publication number: GB2343164A
Application number: GB9925316A
Authority: GB
Inventors: David Carvell
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1998-10-28
Filing date: 1999-10-27
Publication date: 2000-05-03
Also published as: GB9925316D0; GB9823562D0

Abstract

A vehicle includes a heating and ventilating system 10 arranged in use to supply air to a passenger compartment, the heating and ventilating system including a fan 14, an inlet duct 12 for connecting the fan 14 to a source of air and an outlet duct 22 connecting the output of the fan 14 to the passenger compartment. An electronic control unit (ECU) 32 is mounted in a casing 34 which is located inside the inlet duct 12, the casing 32 including an inlet port 36 and an outlet port 38 which are arranged in use to allow a portion of a flow of air passing through the inlet duct 12 to pass through the casing 34.

Description

A Vehicle This invention relates to vehicles and in particular to a cooling arrangement for an electronic control unit associated with a vehicle.

Electronic control units (ECUs) used in vehicles have become increasingly more complicated over the years and the size of some of these units has increased accordingly. This has, in some cases, made it difficult to find sufficient space to mount the electronic control unit (ECU) within the vehicle. Although increasing integration and advances is technology have helped to keep the size of some ECUs down, the need to provide drive for devices such as stepper motors, solenoids, ignition coils and fuel injectors has resulted in many such ECUs generating a significant amount of internal heat, which needs to be dissipated.

One attempt to alleviate this problem is disclosed in WO 97/42056, in which electronic units are mounted on the walls of a by-pass duct of a ventilation system. It is a disadvantage of this arrangement that the bypass duct occupies extra space.

It is an object of this invention to provide an improved vehicle.

Accordingly, the invention provides a vehicle including a heating and ventilating system arranged in use to supply air to a passenger compartment, the heating and ventilating system including an air propelling means, an inlet duct for connecting the propelling means to a source of air and an outlet duct for connecting the propelling means to the passenger compartment, wherein the vehicle further comprises an electronic control unit mounted in a casing which is located inside a said duct, the casing including an inlet port and an outlet port which are arranged in use to allow a portion of a flow of air passing through the said duct to pass through the casing.

A volume of air flow through the casing may be controlled by a temperature responsive valve means, so as to control the temperature of the air within the casing.

The temperature controlled valve means may comprise a bi-metallic flap valve. The casing may be positioned in the outlet duct or in the inlet duct. The inlet port may be connected to the outlet duct. The outlet port may be connected to the outlet duct.

The outlet duct may be of a varying cross-sectional area and the inlet port and the outlet port may both be connected to the outlet duct at spaced apart positions at which the air pressure in the outlet duct is different, such that the air flow is at least in part drawn through the casing as a result of a pressure differential across the casing resulting from the positioning of the inlet and outlet duct connections.

The cross-sectional area of the outlet duct at the position of connection of the inlet port thereto may be less than the cross-sectional area of the outlet duct at the position of connection of the outlet port thereto.

The vehicle may further comprise a heat exchanger unit mounted in the outlet duct between the propelling means and the passenger compartment, wherein both the inlet port and the outlet port are connected to the outlet duct upstream of the heat exchanger.

The vehicle may further comprise a heat exchanger unit mounted in the outlet duct between the propelling means and the passenger compartment, wherein the outlet port is connected to the outlet duct upstream of the heat exchanger.

The invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a cross-section through a heating and ventilation unit forming part of a vehicle according to a first embodiment of the invention; and Figure 2 is a cross-section similar to that of Figure 1, but showing a second embodiment of the invention.

With reference Figure 1, there is shown part of a heating and ventilating system 10 for a vehicle. The heating and ventilating system 10 has an inlet duct 12, into which air can be drawn in by an air propelling means in the form of a fan 14. The inlet duct 12 is connected to a blower housing 16 in which is mounted the fan 14 and its drive motor 18. The inlet duct 12 further includes an air filter 20 for removing particles from the inlet air.

An outlet duct 22 connects the output of the fan 14 to the interior of a passenger compartment via a distribution system (not shown). A heat exchanger 24, in the form of an evaporator forming part of an air conditioning circuit, is mounted in the outlet duct 22. The outlet duct 22 is of varying cross-sectional area and is of a relatively small cross-sectional area in a neck portion 26 of the outlet duct 22 adjacent to the fan 14 and is of a relatively larger cross-sectional area in a chamber portion 28 near to the heat exchanger 24. A second inlet duct 30 is provided for recycling air from the passenger compartment via the fan 14.

An electronic control unit (ECU) 32 is mounted in a housing, which is in the form of a hollow casing 34 located inside the inlet duct 12. The casing 34 has an inlet passage in the form of an inlet port 36, which connects the casing 34 to the neck portion 26 of the outlet duct 22. The casing 34 also has an outlet passage in the form of an outlet port 38, which connects the casing 34 to the outlet duct 22 in the region of the heat exchanger 24.

Two possible positions of connection of the outlet port 38 to the outlet duct 22 are shown. The first is shown as a solid line, is given the reference numeral 38A and represents a connection of the outlet port 38 to the chamber portion 28 prior to/upstream of the heat exchanger 24. The second position is shown by a dotted line, is given the reference numeral 38B and represents a connection of the outlet port 38 to an outlet portion 40 of the outlet duct 22 just after the heat exchanger 24. The choice of connection 38A, 38B can be determined during development tests, the first position 38A being perhaps less favoured because the air exiting the outlet port 38 will have been heated by its passage over the ECU 32 and its up-stream position 38A may be found to cause variations in the efficiency of the heat exchanger 24. The invention will hereafter be described solely with reference to the first position 38A of connection of the outlet port 38.

A temperature responsive valve member in the form of a bi-metallic flap valve 42 is provided to control the flow of air through the casing 34 in dependence upon the temperature of the air within the housing 34. The flap valve 42 opens and closes the inlet port 36 in this embodiment but it would also be possible to use another such or functionally similar valve to open and close the outlet port 38 either in the alternative or in addition to this flap valve 42.

Air flowing in via the inlet duct 12 passes over substantially all the outer surfaces of the casing 34, thereby cooling the casing and the enclosed ECU 32. As the ECU 32 heats up, the temperature of the air within the casing 34 will increase and thereby cause the flap valve 42 to open.

The location of the pipes 36,38 is such that a pressure differential exists between the inlet port 36 and the outlet port 38. While the flap valve 42 is partially or fully open, the pressure differential causes air to flow into the casing 34 via the inlet port 36 and out of the casing 34 through the outlet port 38, thereby further cooling the ECU 32. This flow is produced without the need to provide a separate fan for the ECU 32 (i. e. to propel air through the casing 34).

Referring now to Figure 2, there is shown a second embodiment of the invention in which a casing 340 containing an electronic control unit (ECU) 320 is mounted in an outlet duct 220 between a fan 140 and a heat exchanger 240. The casing 340 has an inlet port 360 connected to a neck portion 260 of the outlet duct 220 and an outlet port 380 connected to an outlet portion 400 of the outlet duct 220 in the region of the heat exchanger 240. In similar fashion to the first embodiment, it would be possible to terminate the outlet port 380 up-stream of the heat exchanger 240 if it was found that the air flowing out of it did not significantly vary or affect the efficiency of the heat exchanger 240.

Again in similar fashion to the first embodiment, a temperature responsive valve member in the form of a bi-metallic flap valve 420 is provided to control the flow of air through the casing 340 in dependence upon the temperature of the air within the housing/casing 340. The flap valve 420 opens and closes the outlet port 380 in this embodiment but it would also be possible to use another such or functionally similar valve to open and close the inlet port 360 either in the alternative or in addition to this flap valve 420.

Operation of this embodiment is similar to that described above, in that initially air passing over the casing 340 is used to cool the ECU 320 until the temperature within the casing 340 rises above a predetermined temperature. The bi-metallic flap valve 420 then opens so as to allow air to pass through the housing 340 to cool the ECU 320.

Claims

CLAIMS 1. A vehicle including a heating and ventilating system arranged in use to supply air to a passenger compartment, the heating and ventilating system including an air propelling means, an inlet duct for connecting the propelling means to a source of air and an outlet duct connecting the propelling means to the passenger compartment, wherein the vehicle further comprises an electronic control unit mounted in a casing which is located inside a said duct, the casing including an inlet port and an outlet port which are arranged in use to allow a portion of a flow of air passing through the said duct to pass through the casing.
2. A vehicle according to Claim 1, wherein a volume of air flow through the casing is controlled by a temperature responsive valve means, so as to control the temperature of the air within the casing.
3. A vehicle according to Claim 2, wherein the temperature controlled valve means comprises a bi-metallic flap valve.
4. A vehicle according to any preceding claim, wherein the casing is positioned in the outlet duct.
5. A vehicle according to any one of Claims 1 to 3, wherein the casing is positioned in the inlet duct.
6. A vehicle according to any preceding claim, wherein the inlet port is connected to the outlet duct.
7. A vehicle according to any preceding claim, wherein the outlet port is connected to the outlet duct.
8. A vehicle according to any preceding claim, wherein the outlet duct is of a varying cross-sectional area and the inlet port and the outlet port are both connected to the outlet duct at spaced apart positions at which the air pressure in the outlet duct is different, such that the air flow is at least in part drawn through the casing as a result of a pressure differential across the casing resulting from the positioning of the inlet and outlet duct connections.
9. A vehicle as claimed in Claim 8, wherein the cross-sectional area of the outlet duct at the position of connection of the inlet port thereto is less than the cross-sectional area of the outlet duct at the position of connection of the outlet port thereto.
10. A vehicle according to any one of Claims 7 to 9, further comprising a heat exchanger unit mounted in the outlet duct between the propelling means and the passenger compartment, wherein both the inlet port and the outlet port are connected to the outlet duct upstream of the heat exchanger.
11. A vehicle according to any one of Claims 7 to 9, further comprising a heat exchanger unit mounted in the outlet duct between the propelling means and the passenger compartment, wherein the outlet port is connected to the outlet duct upstream of the heat exchanger.
12. A vehicle substantially as described herein and with reference to Figure 1 or Figure 2 of the accompanying drawings.