GB2514837A

GB2514837A - A heat shield arrangement

Info

Publication number: GB2514837A
Application number: GB1310176.1A
Authority: GB
Inventors: Thomas Paul Jackson; Jonthan Layfield
Original assignee: Bentley Motors Ltd
Current assignee: Bentley Motors Ltd
Priority date: 2013-06-07
Filing date: 2013-06-07
Publication date: 2014-12-10
Anticipated expiration: 2033-06-07
Also published as: GB2514837B; GB201310176D0

Abstract

A heat shield arrangement for protecting a component installed in an engine compartment. The heat shield arrangement includes a heat shield 11 and a duct 18 for directing a flow of cooling air between the heat shield and a component protected by the heat shield. The heat shield may comprise a surround 12 and a cover 15. The duct may extend from the heat shield to an open end for collecting and/or extracting air. A vehicle comprising the heat shield arrangement is also provided. The component may be an engine mount 5 and the heat shield may be configured to protect the engine mount. The engine may comprise a turbocharger 8 and the heat shield may be positioned between the engine mount and the turbocharger. The engine may comprise an engine cooling fan 10 and the duct may be positioned to collect a flow of cooling air from the engine cooling fan.

Description

A HEAT SHIELD ARRANGEMENT

Technical Field of the Invention

The present invention relates to a heat shield arrangement for protecting a component installed in an engine compartment and to a vehicle comprising an engine compartment and a heat shield arrangement protecting a component in the engine compartment.

Background to the Invention

There is a strong desire to improve the performance and specification of automobiles. As such, automobile engines and other equipment arc continually increasing in complexity, quantity and often size as a result. This presents packaging problems in accommodating the equipment in the limited space available in an automobile's engine compartment. A particular problem arises when components that generate heat, such as turbochargers and exhaust systems, have to be positioned close to heat sensitive components, such as engine mounts. This is both impractical andpotentially dangerous.

Engine mounts isolate a vehicle structure from engine vibration. Engine mounts typically comprise complex elastomer elements with carefully developed stiffness and damping properties. These carefully developed properties may alter and/or materials may degrade when subject to heat, causing malfunction oL or permanent damage to, the engine mount as a result.

Embodiments of the present invention address some or all of these problems.

Summary of the Invention

According to a first aspect ofthc present invention, there is provided a heat shield arrangement for protecting a component installed in an engine compartment, the heat shield arrangement comprising a heat shield and a duct for directing a flow of cooling air between the heat shield and a component protected by the heat shield.

According to a second aspect of the invention there is provided a vehicle comprising an engine compartment with a heat shield arrangement according to the first aspcct of thc invcntion installed in thc cnginc compartmcnt to protcct a componcnt installed in the engine compartment.

Thc hcat shicld is ablc to protcct a componcnt from hcat radiatcd from anothcr component. Provision ofthe duct enables the build up of hot air around the componentto be minimised as well as carrying away heat that may build up in the heat shield.

The heat shield may be substantially similar in shape to the shape of the component being protected. The heat shield may be formed from a textured aluminium sheet or woven glass composite or combination thereof.

The heat shield may comprise a surround and a cover. The surround may comprise a generally cylindrical wall and the cover may comprise a depending generally cylindrical wall. These generally cylindrical walls may have a close clearance fit or flexible coupling enabling the cover to be mounted to the surround.

The cover may have a single gap in its generally cylindrical wall and the surround may have two adjacent gaps in its generally cylindrical wall. The single gap may be substantially similar in shape and size to the two adjacent gaps. As such, if the cover is mounted over the surround, there may be two gaps in the substantially cylindrical wall of the combined cover and surround arrangement. One of these gaps may be used for the attachment of the duct, the other may allow for air to flow between the heat shield and the engine compartment.

The duet may extend from the heat shield to an open end fbr collecting and/or extracting air. The open end may be positioned higher than the heat shield and the duct may have no downward path as it extends from the heat shield to the open end. Such arrangement is advantageous fin generating a cooling air flow over the component protected by the heat shield, since any heat absorbed by the heat shield or the component will risc up and out of the duct and will be replaced by cooler air once thc vehicle is stationaty.

The duct may be lbrmcd from a sheet metal or plastics material able to withstand the temperature conditions of an automobile engine compartment, although any other suitable material could be used.

The engine compartment may comprise an engine mount and the heat shield arrangement may be positioned to protect the engine mount.

The engine compartment may further comprise a turbocharger and the heat shield maybe positioned between the engine mount and the turbocharger in order to protect the engine mount from heat radiated by the turbocharger.

The heat shield may be mounted relative to the component protected by the heat shield such that there is an air gap between the heat shield and the component protected by the heat shield. This air gap provides a cooling channel to evenly distribute the cooling air onto the protected component and the heat shield, directly cooling the protected component and helping to prevent the heat shield from heating up and radiating heat to the protected component. An air gap is also beneficial lbr reducing the heat transferred to the protected component from the heat shield via conduction, if the heat shield becomes hot.

The duet may be positioned to collect a flow of cooling air generated from the movement of a vehicle. The engine compartment may comprise an engine cooling fan and the duct may be positioned to collect a flow of cooling air from the engine cooling fan. This is advantageous, as by taking advantage of vehicle movement and!or airflow generated by an existing fan no additional arrangement is required to generate a cooling airflow to or from thc heat shield.

The vehicle may further comprise an engine and an electronic control unit, and the engine cooling fan may be driven by an electric motor under the control of the electronic control unit. The electronic control unit may be arranged to cause the engine cooling fan to run for a set period oftime after the engine is switched off This avoids the protected component from becoming overheated as a result of "heat soaking" due to air flow ceasing when the engine is switched off until relevant engine components have cooled to a sufficient extent.

The vehicle may further comprise one or more temperature monitoring sensors connected to the electronic control unit, and the electronic control unit may be arranged to control the fan in dependence upon the temperature measured by the one or more sensors. The temperature ofthe engine, engine compartment and/or engine mount may be monitored. The fan may, therefore, automatically be switched on to cool a protected component when a measured temperature exceeds a predetermined threshold, beyond which there is a risk that the temperature of the component could reach a level at which materials may degrade and!or component function may deteriorate.

Detailed Description of the Invention

In order that the invention maybe more clearly understood embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows an automobile comprising an engine compartment; Figure 2 is a schematic diagram ofthe engine compartment of figure 1; Figure 3 is an exploded yiew of parts of the engine compartment of figure 2; and Figure 4 is an alternative view of parts of the engine compartment of figure 2.

Referring to the figures, an automobile 1 comprises an engine compartment 2.

The engine compartment 2 houses an internal combustion engine with a cylinder block 3 mountcd to a subframe 4 via an engine mount 5 and engine mount bracket 6. An exhaust manifold 7 is mounted to the cylinder block and connects to a turbocharger 8, which is positioned adjacent to the engine mount 5. Towards the front of the engine is a radiator (not shown), bchind which sits a cooling fan 9 disposcd in a cowl 10. The radiator is positioned towards the front ofthe automobile. The cooling fan 9 is driven by an electric motor under the control of the automobile's electronic control unit. At least one temperature monitoring sensor, operable to monitor the temperature ofthe engine, engine compartment and/or engine mount, is also coimected to the electronic control unit.

A heat shield 11 is mounted over the engine mount so that it is positioned between the engine mount and the turbocharger to thereby shield the engine mount from heat generated by the turbocharger. The heat shield comprises a surround 12. The surround has a generally cylindrical wall 13 with two adjacent gapsl4a, 14b in it, and it sits around the engine mount such that there is an air gap between the engine mount and the cylindrical wall.

The heat shield also comprises a cap 15. The cap is dome shaped, substantially matching the shape ofthe top ofthe engine mount, with a depending cylindrical wall 16.

This cylindrical wall has a gap 17 which substantially matchcs thc sizc and shapc ofthc two adjacent gaps (in combination) in the cylindrical wall of the surround. The cylindrical wall of the cap is sized so it has a close clearance fit with the outside of the cylindrical wall of the surround. The cap is mounted over the surround so that the cylindrical wall ofthe cap extends around the outside ofthe surround with its gap aligned with the gaps in the surround, such that the gaps are on the side of the engine mount farthest away from the turbocharger. The cap is sized so that an air gap extends over the top of the engine mount, between the cap and the engine mount.

One of the gaps in the surround provides an air gap through which air can flow between the air gap between the engine mount and the heat shield and the engine compartment.

A duct 18 is coimected to the other gap in the cylindrical walls ofthe combined cap and surround arrangement, and communicates with the inside of the heat shield. The duct is formcd from a plastics matcrial able to withstand thc tcmpcraturc conditions of an automobile engine compartment, although any other suitable material could be used. The duct extends from the heat shield generally horizontally towards the cooling fan and then turns through approximately 90 degrees to extend generally vertically up to approximately the height midway between the bottom of the cowl and the centre of the cooling fan. The duct again turns through approximately 90 degrees to extend generally horizontallyto an opening 19 which sits behind the cooling fan. This opening is forward facing, facing the cooling fan and the front of the automobile.

When the automobile engine is running, hot exhaust gases flow through the exhaust manifold and turbocharger causing these components to heat up. Temperatures typically rcach 800°C and at such tempcraturcs thcrc is significant hcat radiatcd to thc engine compartment and heat sensitive components such as engine mounts. Since the heat shield is positioned between the turbo charger and the engine mount, it absorbs radiated heat that would otherwise be absorbed by the engine mount. Subsequently, over time, the heat shield will heats up and can subsequently radiate heat to the engine mount.

This problem is reduced/eliminated by the provision of the duct.

In use, a cooling air flow is generated by the forward movement ofthe automobile and/or by operation of the cooling fan. The opening of the duct, facing the cooling fan and the front of the automobile, scavenges this cooling air flow and the duct directs it into the air gap between the engine mount and heat shield. The air gap provides a cooling channel to evenly distribute the cooling air onto the engine mount and the heat shield, dircctly cooling thc engine mount and helping to prevent the heat shield from heating up and radiating heat to the engine mount.

Whcn thc automobile engine is not running, the cooling fan can be programmed to stay operate, allowing for the dispersion of any residual heat of the engine mount and/or heat shield. The cooling fan can be programmed to operate on for a set period of time once the automobile engine has stopped running and/or it can be programmed to operate onthe basis ofthe temperature ofthe engine, engine compartment and/or engine mount, coming on automatically when the monitored temperature reaches a threshold value and turning off automatically once the temperature has dropped below the threshold value. This threshold value would be much lower than the temperature at which the fhnetion of the engine mount would deteriorate, so that on exceeding this threshold temperature, the engine mount can be cooled down before reaching a temperature at which its fitnetion would deteriorate.

Even when there is no forward motion of the vehicle and the cooling fan is not running, the duet provides an effective way of generating an air flow over the engine mount. Due to the curved shape of the duet, extending generally horizontally and then generally vertically, any hot air trapped between the heat shield and the engine mount will tend to rises up the duct and out towards the cooling fan and the front of the automobile. This hot air is replaced by cooler air from outside ofthe automobile's engine compartment, generating a cooling air flow.

Embodiments of the invention allow for heat generating components, such as turbochargers, and heat sensitive components, such as engine mounts, to be positioned in close proximitywithin an automobile's engine compartment without compromising their operation. Whilst the heat shield acts as a barrier, protecting the heat sensitive component from radiated heat, the provision of the duct additionally keeps the heat sensitive component cool and also enables any heat generated in the heat shield to be directed away from the heat sensitive component. This enables automobile engine compartment components to be better and more space efficiently arranged, providing more space for improved and!or additional components.

The above embodiments are described bywayofexample only. Manyvariations are possible without departing from the scope ofthe invention as defined in the appended claims.

Claims

CLAIMS1. A heat shield arrangement for protecting a component installed in an engine compartment, the heat shield arrangement comprising a heat shield and a duct for directing a flow of cooling air between the heat shield and a componentprotected by thc heat shicld.
2. A heat shield arrangement as claimed in claim 1, wherein the heat shield comprises a surround and a cover.
3. A heat shield arrangement as claimed in claim 2, wherein the surround comprises a generally cylindrical wall and the cover comprises a depending generally cylindrical wall, and these generally cylindrical walls have a close clearance fit enabling the cover to be mounted to the surround.
4. A heat shield arrangement as claimed in claim 3, wherein the cover has a single gap in its generally cylindrical wall and the surround has two adjacent gaps in its generally cylindrical wall, and the single gap is substantially similar in shape and size to the two adjacent gaps.
5. A heat shield arrangemcnt as claimed in any preceding claim whcrein the duct extends from the heat shield to an open end for collecting and/or extracting air.
6. A heat shield arrangement as claimed in claim 5, wherein the open end is positioned higher than the heat shield.
7. A heat shield arrangement as claimed in either of claims 5 or 6, wherein the duct has no downward path as it extends from the heat shield to the open end.
8. A vehicle comprising an engine compartment with a heat shield arrangement as claimed in any preceding claim installed in the engine compartment to protect a component installed in the engine compartment.
9. A vehicle as claimed in claimS, wherein the engine compartment comprises an engine mount and the heat shield arrangement is positioned to protect the engine mount.
10. A vehicle as claimed in claim 9, wherein the engine compartment further comprises a turbocharger and the heat shield is positioned between the engine mount and the turbocharger.
11. A vehicle as claimed in anyofclaims 8 to 10, wherein the heat shield is mounted relative to the component protected by the heat shield such that there is an air gap between the heat shield and the component protected by the heat shield.
12. A vehicle as claimed in any of claims 8 to 11, wherein the duct extends from the heat shield to an open end fin collecting and/or extracting air.
13. A vehicle as claimed in claim 12, wherein the open end is positioned higher than the heat shield.
14. Avehicleasclaimedinanyofclaims 12 or 13, whereinthe duct hasno downward path as it extends from the heat shield to the open end.
15. A vehicle as claimed in any of claims 8 to 14, wherein the duct is positioned to collect a flow of cooling air generated from the movement of a vehicle.
16. A vehicle as claimed in any of claims 8 to 15, wherein the engine compartment comprises an engine cooling fan and the duct is positioned to collect a flow of cooling air from the engine cooling fhn.
17. A vehicle as claimed in claim 16, wherein the vehicle Ilirther comprises an engine and an electronic control unit, and the engine cooling fltn is driven by an electric motor under the control of the electronic control unit.
18. A vehicle as claimed in claim 17, wherein the electronic control unit is arranged to cause the engine cooling fan to run for a set period of time after the engine is switched off.
19. A vehicle as claimed in either of claims 17 or 18, wherein thc vehicle further comprises one or more temperature monitoring sensors connected to the electronic control unit, and thc clcctronic control unit is arranged to control the fan in dependence upon the temperature measured by the one or more sensors.
20. A heat shield arrangement substantially as herein described with reference to any of the accompanying drawings.
21. A vehicle substantially as herein described with reference to any of the accompanying drawings.