WO2004085209A1

WO2004085209A1 - A vehicle electronic control unit

Info

Publication number: WO2004085209A1
Application number: PCT/GB2004/001197
Authority: WO
Inventors: Geoffrey Leslie Heathcote; Marek Fabian Koncki; Martin Kenneth Henry; Andrew Reynolds; Mark Daniel Thompson
Original assignee: Trw Limited
Priority date: 2003-03-26
Filing date: 2004-03-19
Publication date: 2004-10-07
Also published as: GB0306917D0

Abstract

A vehicle electronic control unit (1), comprising a circuit board (11) having mounted thereon at least one electronic component (15), a cooling member in thermal contact with the circuit board (11) and comprising a plate (10) having a pipe (9) associated therewith arranged to allow a cooling fluid to flow therein. The circuit board (11) and the cooling member are covered by a cover (2) fabricated from a plastic material.

Description

A VEHICLE ELECTRONIC CONTROL UNIT

This invention relates to a vehicle electronic control unit (ECU) especially, but not exclusively, for use in a motor vehicle and also relates to a housing for such a control unit.

Modern motor vehicles generally have sophisticated electronic control systems that control the function of the engine of the motor vehicle as well as other systems of the vehicle. Such control units are essential to the functionality of a modern motor vehicle in order that it can meet modern emission requirements, fuel consumption requirements, and the like.

When an ECU is mounted in the engine compartment of a motor vehicle it will be subjected to a range of temperatures and harsh environmental conditions. The temperatures may vary depending upon the position of the ECU within the engine compartment and may be most severe when the ECU is mounted adjacent to, or on the engine itself. Added to these temperatures is the heat generated by the electronic components themselves within the ECU assembly. There is a need, not only to protect the electronic components from the environmental conditions, but also to dissipate the heat generated within the ECU such that the efficiency of the ECU is not impaired.

In such installations it has been known to manufacture respective parts of the ECU housing from a metal, such as aluminium in order that it can withstand the environmental conditions, and also provide the heat dissipating capability. However, such aluminium housings tend to be heavier than may be desired, may be more costly to manufacture than may be desired and may be subject to corrosion. One such prior art vehicle control unit is shown in US 6 302 190.

Light weight housings may be utilised if the control unit is situated away from the engine. However, this in itself is disadvantageous since moving the control unit away from the engine introduces the need for longer connections to sensors monitoring the engine. Longer connections themselves introduce more weight and also add to the overall cost.

According to a first aspect of the invention there is provided a vehicle electronic control unit, comprising a circuit board having mounted thereon at least one electronic component, a cooling member in thermal contact with the circuit board and comprising a plate having a pipe associated therewith arranged to allow a cooling fluid to flow therein, and the circuit board and the cooling member being covered by a cover fabricated from a plastics material.

Such an electronic control unit is advantageous because the, or each, electronic component is covered by a cover and thus protected from the environment outside the cover and yet may be readily cooled by the cooling member. A further advantage may be that the mass of the control unit may be reduced when compared to the prior art due to the choice of material of the cover. It has previously been believed that plastics materials were not suitable for control unit covers for certain installations, due to their thermally insulating properties.

Conveniently, the cover comprises a first portion and a second portion, which are arranged to come together to encapsulate the circuit board and the cooling member therewithin. Such an arrangement is advantageous because it can help to provide a sealed environment in which the circuit board is protected. The cover may be a separate moulding or may be overmoulded over the cooling member, with the circuit board then being assembled to the cooling member. There may be a seal provided between the two portions; this may be formed as a co-moulding with one of the portions, or alternatively, the two portions may be laser- welded together in which case the seal may be omitted.

Preferably, the plastics material of the cover is a thermosetting plastics material. For example, the plastics material may , be any one of the following, non exhaustive list of materials such as PBT, PET, Nylon or the like or a specially engineered composite of similar plastics. Such plastics materials are thought to be advantageous because they are readily formable, lightweight and yet inexpensive.

In perhaps a preferred embodiment the pipe is arranged such that fuel for an engine of the vehicle for which the control unit is intended can be used as the cooling fluid. For example, the fuel may be petrol, diesel, LPG, or the like. Such an arrangement is convenient because the fuel can provide an effective cooling fluid.

Conveniently, the pipe has a substantially "D" shaped cross section, preferably, with the flat portion of the "D" adjacent the cooling member. Such an arrangement is convenient because it helps to increase the surface of contact between the pipe and the cooling member, which in turn may help to increase the amount of heat that is transferred to the cooling fluid. The pipe may follow the periphery of the plate, and may define a "U" shape.

The pipe is preferably welded to the cooling member, but may also be bonded, soldered, brazed, adhered, clamped, or otherwise held in contact with the cooling member. The pipe may be formed by extrusion. The cover may be provided with one or more, and more preferably at least two, ports arranged to allow the cooling fluid to be passed through the pipe.

Conveniently, the cooling member comprises a plate, which may have the circuit board located on a first side and the pipe on a second side opposite the first. The plate may have the same outline as the circuit board, or may define a "U" -shape about its periphery. Having a plate is a convenient structure since it can help to provide mechanical rigidity to the cover.

The cooling member may be formed of metal or metal materials. One or more of pipe and plate may be formed of aluminium. Alternatively, the pipe and plate may be formed of two different heat conductive materials .

The plate may have raised portions which are arranged to contact and locate the circuit board. Such an arrangement is convenient because it can help to ensure that the circuit board and cooling member contact each other as desired and therefore may reduce the likelihood of a short circuit between the two. In a preferred embodiment, the raised portions are stamped or pressed out of the plate; this is particularly convenient to manufacture.

Conveniently, the circuit board substantially has one or more components mounted on a first side and the cooling member associated with a second side.

Preferably, the circuit board is arranged such that components mounted thereon, which may be power components, are in contact with or in close proximity to the raised portions of the plate. Such an arrangement is convenient because, as the skilled person will appreciate certain 4/085209

5 components (and in particular power components) need more cooling than others and as such may be advantageous to mount these directly on the cooling member. The circuit board may have apertures therein to allow power components to be mounted on or arranged adjacent to the raised portion of the cooling member.

A heat transfer means, such a heat transfer compound, paste, thermally conductive adhesive, or the like, may be used between the cooling member and the circuit board. Such an arrangement helps to ensure efficient conduction of heat to the cooling member.

Electrical connectors may be provided on the second side of the circuit board such that they pass through openings in the cooling member when the circuit board is mounted on the cooling member. The electrical connectors preferably pass through the openings in the cooling member to engage the external connectors in the cover member. A further advantage arises from arranging the cooling member in this way in that it provides an electro-mechanical shield against emissions from the processors and other components mounted on the circuit board. Moreover, the degree of shielding may be chosen by varying the shape or size of the respective openings.

The cover may be provided with a number of anti-vibration mountings by means of which the electronic control unit can be mounted to the vehicle and be isolated from vibrations from the vehicle. The mountings may be co-moulded with the cover.

According to a second aspect of the invention, there is provided a housing for an electronic control unit, which comprises a cooling member including a plate having a pipe associated therewith and being arranged to allow a cooling fluid to flow therein, the cooling member being arranged /085209

6 to receive a circuit board and the housing further comprising a cover fabricated from a plastics material that when mounted on the cooling member defines a space for the circuit board to be received therein.

The second aspect of the invention may comprise any of the features discussed in association with the first aspect of the invention.

There now follows, by way of example, an embodiment of the invention with reference to the accompanying drawings, in which:

Figure 1 shows an electronic control unit according to the present invention;

Figure 2 shows an exploded, sectioned, view of the electronic control unit of Figure 1 ;

Figure 3 shows a further exploded view of the electronic control unit of Figure 1 ; and

Figure 4 shows a cross section through the printed circuit board and heat plate of the electronic control unit of Figure 1.

The electronic control unit (ECU) 1 shown in the accompanying drawings may typically be used in the engine compartment of a motor vehicle to control various functions of the vehicle. It comprises a circuit board (PCB) 11 upon which electronic components such as component 15 are mounted in the customary fashion. The components on the circuit board are mounted on a first side thereof.

There is also provided a pressed aluminium heat plate 10 comprising a generally flat plate, with a plurality of half-sheared raised areas 10a, 10b, 4/085209

7 10c spaced around its surface. The raised areas are of the order of 0.5mm in depth. The side of the PCB 11 on which no, or fewer, components are mounted is positioned adjacent these raised areas 10a, 10b, 10c and is thereby spaced from the main body of the heat plate 10. This defines a space, which is filled with a thermally conductive adhesive 14 in order to fix the PCB 11 to the heat plate 10 and transfer as much heat energy as possible from the PCB 11 to the heat plate 10.

The PCB 11 will typically have a number of power components 15 mounted thereon that dissipate a particularly large amount of heat energy. As exemplified by the component 15 shown in Figure 4 of the accompanying drawings, these components can be mounted over an aperture in the PCB 11. A raised area 10b of the heat plate 11 of greater depth than the raised areas used to support the PCB extends partially into the aperture. Thermally conductive adhesive 14 or other heat transfer compound can then be used to fill the remaining space in the aperture between surfaces 10c and 15a ensuring that the relevant components 15 are in good direct thermal contact with the heat plate 10.

The heat plate 10 is further provided with a cooling pipe 9. In use, fluid such as vehicle fuel flows through the pipe in order to carry heat energy away from the ECU. The cooling pipe 9 is formed of extruded aluminium and is of "D "-shaped cross section, with a central bore for fluid flow. The pipe 9 extends in a "U"-shape around the periphery of the heat plate, with the flat of the "D" joined to the side of the heat plate 10 not in contact with the PCB 11, in order to maximise the amount of heat energy that is carried to the fluid. The heat pipe 9 is fixed to the main body of the heat plate 10 by means of welding, bonding or other similar suitable process. 4/085209

8

The ECU 1 further comprises a first portion of a cover 2, which covers the side of the heat plate 10 opposite to the PCB 11. This may be in the form of an overmoulding, although it is appreciated that this could be, in an alternative embodiment, a separate moulding. The cover 2 initially provides a housing for the heat plate 10 and has a shaped portion 5 to accept pipe 9. The cover 2 is integrally moulded with a number of electrical connectors 3, 4. These connectors 3, 4 are in register with similarly sized apertures 12, 13, in heat plate 10 to allow electrical contact with the relevant areas of PCB 11 when the PCB 11 is assembled to the heat plate 10. The PCB 11 is secured to the cover 2 by way of heat stakes which are formed on the cover 1 and pass through openings in both the heat plate 10 and the PCB 11 in manner that will be understood by those skilled in the art.

The heat plate 10 provides an electro-machanical shield against emissions from the electronic components of the PCB 11. Although the apertures 12 and 13 in the heat plate 10 are shown as rectangular, they may be of any other selected shape or size in order to provide the desired degree of electro-magnetic shielding for any given assembly.

The cover 8 is also formed with an anti- vibration moulding 8a, 8b, 8c, 8d at each corner to allow mounting to the relevant part of the vehicle. These are co-moulded with the cover 2. A rear cover plate 2a, providing a second portion of the cover, completes the housing by covering the opposite side of the PCB 11 to the heat plate 10, engaging with cover 2 through a seal co-moulded with the cover 2. Fluid inlet 6 and outlet 7 ports are provided in the cover 2, which engage the two ends of the pipe to allow introduction and extraction of the cooling fluid.

Both cover 2 and rear cover plate 2a are fashioned from conventional thermo-setting plastics such as PBT, PET, Nylon or a specially engineered composite of similar plastics. Use of the heat plate described herein allows use of such, normally heat-retentive, materials which is advantageous due to plastics material's low cost, low weight and good mechanical strength characteristics. The heat plate 10 also increases the rigidity of the assembly compared to a conventional all-plastics materials ECU housing.

Claims

4/08520910CLAIMS

1. A vehicle electronic control unit (1), comprising a circuit board (11) having mounted thereon at least one electronic component (15), a cooling member in thermal contact with the circuit board (11) and comprising a plate (10) having a pipe (9) associated therewith arranged to allow a cooling fluid to flow therein, and the circuit board (11) and the cooling member being covered by a cover (2) fabricated from a plastics material.

2. A vehicle electronic control unit (1) according to claim 1 in which the cooling member is formed of metal or metal materials .

3. A vehicle electronic control unit (1) according to claim 1 or claim 2 in which the pipe (9) has a substantially "D" shaped cross section and in which the flat portion of the "D" is adjacent the cooling member.

4. A vehicle electronic control unit (1) according to any preceding claim in which the pipe (9) is arranged such that fuel for an engine of the vehicle for which the control unit (1) is intended is used as the cooling fluid and in which the pipe contains cooling fluid which comprises fuel for the vehicle.

5. A vehicle electronic control unit (1) according to any preceding claim in which the cover (2) comprises a first portion (2) and a second portion (2a), which are arranged to come together to encapsulate the circuit board (11) and the cooling member there within.

6. A vehicle electronic control unit (1) according to any preceding claim in which the cover (2) is overmoulded over the cooling member.

7. A vehicle electronic control unit (1) according to any preceding , claim in which the cooling member comprises a plate (10) and in which the circuit board is located on a first side of the plate (10) and the pipe (9) on a second side of the plate opposite the first.

8. A vehicle electronic control unit (1) according to claim 7 in which the plate (10) has raised portions (10a, 10b, 10c) which are arranged to contact and locate the circuit board (11).

9. A vehicle electronic control unit (1) according to claim 8 in which the circuit board (11) is arranged such that components (15) thereon, which may be power components, are in contact with or close proximity to the raised portions (10a, 10b, 10c) of the plate (10) .

10. A vehicle electronic control unit (1) according to any preceding claim in which electrical connectors (3,4) are provided on the second side of the circuit board (11) such that they pass through openings (12, 13) in the cooling member when the circuit board (11) is mounted on the cooling member.

11. A vehicle electronic control unit (1) according to claim 10 in which the electrical connectors (3,4) pass through the openings (12, 13) in the cooling member to engage the external connectors in the cover member (2).

12. A vehicle electronic control unit (1) according to any preceding claim in which the cover (2) is provided with a number of anti-vibration mountings (8a, 8b, 8c, 8d) by means of which the electronic control unit (1) is mounted to the vehicle and is isolated from vibrations from the vehicle.

13. A housing for an electronic control unit (1) according to any preceding claim.

14. A vehicle electronic control unit (1), comprising a cooling member having a pipe (9) associated therewith in which the pipe contains cooling fluid which comprises fuel for the vehicle.

15. A vehicle electronic control unit (1) substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

16. A housing for an electronic control unit (1) substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.