GB2562232A

GB2562232A - Heat retention structure and method

Info

Publication number: GB2562232A
Application number: GB1707320.6A
Authority: GB
Inventors: Hutchins William
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-05-08
Filing date: 2017-05-08
Publication date: 2018-11-14
Anticipated expiration: 2037-05-08
Also published as: DE102018206357A1; GB2562232B; GB201707320D0; GB2562232A8

Abstract

An engine heat retention structure 130, and a method of use thereof, are disclosed. The structure comprises a thermal shell 130S arranged to at least partially encapsulate an engine 121 in use, the shell being provided in a spaced apart relationship with the engine to allow circulation of air between the shell and engine. Air is allowed to flow into and out from the structure between the engine and shell via an open skirt portion 130SS. Air is allowed to flow out of the structure via at least one vent flap element 131,133, depending on whether the flap element(s) is/are open or closed. The flap(s) may comprise a pivotable flap portion opened by air flow passing a paddle portion. The flap(s) may be biased with a counterweight arrangement. The structure may be divided into portions via an interior baffle/wall. The engine may be for a motor vehicle.

Description

HEAT RETENTION STRUCTURE AND METHOD

FIELD OF THE INVENTION

Aspects of the present invention relate to improvements in the efficiency of vehicle operation. In particular, aspects of the present invention relate to a structure for promoting engine heat retention when the engine is not in use, to an engine, to a motor vehicle and to a method.

BACKGROUND

The efficiency of internal combustion engines is known to be dependent at least in part on the viscosity (and therefore the temperature) of the oil used to lubricate the cylinders of the engine. Accordingly, it is desirable for internal combustion engines to be able to attain their normal operating temperature as quickly as possible following a cold start.

It is known to provide a layer of thermal insulation over portions of an engine in order to reduce heat loss when the vehicle is parked for extended periods. However, it is desirable to further reduce heat loss whilst a vehicle is parked whilst still obtaining effective engine cooling during vehicle operations.

It is against this background that the present invention has been conceived. Embodiments of the invention provide a structure, a method or a vehicle which addresses the above problems. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.

SUMMARY OF THE INVENTION

In an aspect of the invention for which protection is sought there is provided an engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine in use, the shell being arranged to be provided in a spaced apart relationship with the engine thereby to allow circulation of air between the shell and engine, the shell comprising an open skirt portion arranged to allow air to flow into and out from the heat retention structure between the engine and shell, the structure being provided with at least one vent flap element through which air may flow out from the heat retention structure in dependence on whether the at least one vent flap element is in an open condition or a closed condition.

Embodiments of the present invention have the feature that air surrounding the engine within the thermal shell that becomes heated by the engine, therefore having greater buoyancy than ambient air, will remain substantially trapped within the shell unless the at least one vent flap element is in the open position.

However, if the at least one vent flap element is opened, heated air can escape from the shell via the vent flap element. If air is forced upwardly into the thermal shell due to movement of the vehicle or the action of a fan device, air may also be driven out from the shell by passing below a lower edge of the skirt portion, which is open.

Advantageously, when the engine is switched off and air is no longer being forced upwardly into the thermal shell due to movement of the vehicle, ambient air heated by the engine block may remain substantially trapped within the volume defined by the shell by closing the at least one vent flap element. This reduces the rate of cooling of the engine when switched off.

It is to be understood that embodiments of the present invention have the advantage that circulation of relatively cool, ambient air may take place over the engine block when the engine is in use. However, whilst the engine is switched off, air warmed by the engine may be trapped between the engine and shell, reducing the rate of cooling of the engine. Accordingly, the probability that the engine will still be at a temperature above ambient temperature when it is next switched on is increased, resulting in engine starting with oil of lower viscosity than in known motor vehicles, and resulting in lower emissions and higher fuel economy. Higher engine temperatures at start-up may also increase the rate at which an engine after-treatment system warms to its normal operating temperature, further reducing emission of unwanted gases.

The open skirt portion may comprise a first edge that defines an opening arranged to allow air to flow into and out from the heat retention structure.

The shell may comprises a first surface located diametrically opposite the opening defined by the first edge of the open skirt portion.

The at least one vent flap element may be located closer to the first surface of the shell than the first edge of the open skirt portion.

At least one vent flap element may be located on the first surface.

At least one vent flap element is located on the open skirt portion.

The open skirt portion may be downwardly directed, in use, with respect to a normal upright orientation of a motor vehicle.

The open skirt portion may be arranged to substantially surround the engine block such that substantially the whole of the engine block is within the shell portion.

Optionally, the at least one vent flap element is arranged to open automatically and close automatically in dependence at least in part on the flow rate of air on an inside of the thermal shell between the engine and thermal shell in use.

Optionally, the at least one vent flap element comprises a flap portion pivotable about an axis between a closed position and an open position and a paddle portion, the paddle portion being exposed to air flow on an inside of the shell in use, wherein the flap portion may be caused to pivot reversibly between the closed and open positions in dependence at least in part on a force imposed on the paddle portion due to air flow within the thermal shell.

This feature has the advantage that the at least one vent flap may be arranged automatically to close when the vehicle is stationary, the engine is switched off, and ambient air is no longer being blown upwardly into the thermal shell. Consequently, ambient air between the engine and thermal shell that is warmed by the engine remains substantially trapped within the thermal shell. This results in a decrease in the rate of cooling of the engine relative to an engine not having a thermal shell.

Optionally, the at least one vent flap element comprises biasing means arranged to bias the flap portion to the closed position.

Optionally, the biasing means comprises a counterweight arrangement whereby the flap portion is biased to the closed position under gravity.

Thus, for example, the flap portion and paddle portion may be arranged in a see-saw configuration each on opposite sides of the pivot, and arranged such that if the flap portion is in the open position, in the absence of a force due to air flow on the paddle portion the flap portion pivots to the closed position under the influence of gravity.

Alternatively the biasing means may comprise a spring element such as a helical coil spring.

The structure may comprise at least one baffle portion comprising a wall arranged to span a gap between the thermal shell and engine, the baffle portion being arranged to substantially prevent flow of air there past in use.

Optionally, the wall of the at least one baffle portion is arranged in a substantially vertical orientation.

Optionally, the baffle portion is arranged to at least partially restrict flow of air from one side of the engine to an opposite side in use.

This feature has the advantage that it may promote efficient laminar flow of air around the engine during engine running, when air is forced up the skirt and over the engine, reducing turbulent flow around the engine. This may enhance cooling and, in some embodiments, reduce vehicle drag.

In an aspect of the invention for which protection is sought there is provided a structure according to another aspect in combination with an air velocity deflector portion configured to direct air into the heat retention structure between the engine and thermal shell in use.

Optionally, the air velocity deflector portion comprises an air duct configured to direct air into the heat retention structure between the engine and thermal shell in use.

The structure may be provided in combination with an air blower device configured to direct air into the heat retention structure between the engine and thermal shell.

The structure may comprise at least one actuator for opening and closing at least one said at least one vent flap.

This feature has the advantage that the at least one vent flap may be prevented from closing, even in the absence of air flow within the shell. For example, it may be advantageous to keep the at least one vent flap open if the vehicle is stationary with little or no ambient air being forced to flow within the shell. One or more portions of the engine may otherwise attain a relatively high or excessive temperature, for example due to the presence of a substantial amount of heat energy within one or more regions of the engine.

The actuator may comprise an electric motor, solenoid device or any other suitable actuator.

Optionally, the structure is configured wherein when at least one said at least one vent flap element is in the open condition, air is permitted to flow out from the volume enclosed by the shell at a level above the lower edge of the skirt portion, and when each said at least one vent flap element is in the closed condition, air is substantially prevented from flowing out from the volume enclosed by the shell at a level above the lower edge of the skirt portion.

The structure may comprise an open skirt portion downwardly directed, in use, and arranged in use to at least partially surround the engine.

In an aspect of the invention for which protection is sought there is provided a structure according to another aspect in combination with an engine.

In another aspect of the invention for which protection is sought there is provided a motor vehicle comprising an engine provided with an engine heat retention structure (130) according to another aspect.

The motor vehicle may further comprise a radiator pack comprising a radiator and air blower device, the air blower device being arranged in use to direct air towards the air velocity deflector portion such that the air flows into the thermal shell.

The air velocity deflector portion may be arranged to direct air that has passed over or through the radiator device into the thermal shell from below the thermal shell.

In an aspect of the invention for which protection is sought there is provided a method of heat retention comprising providing an engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine in use, the shell being arranged to be provided in a spaced apart relationship with the engine thereby to allow circulation of air between the shell and engine, the shell comprising an open skirt portion arranged in use to at least partially surround the engine, the method comprising allowing air to flow into and out from the heat retention structure via the open skirt portion of the thermal shell, the method comprising allowing air to flow out from the heat retention structure via at least one vent flap element in dependence on whether the at least one vent flap element is in an open condition or a closed condition.

Optionally, when the at least one vent flap element is in the closed condition, air is substantially prevented from exiting the thermal shell at a level above the lower edge of the skirt portion.

The method may comprise, following an engine start, maintaining at least one said at least one vent flap element closed until at least one predetermined vent flap opening condition is met.

Optionally, the at least one predetermined vent flap opening condition comprises the condition that the engine temperature is not less than a predetermined minimum vent flap opening temperature.

Thus the method may comprise opening and closing at least one said at least one vent flap by means of an actuator such as an electric motor, solenoid device or any other suitable actuator.

The method may comprise, following an engine shutdown, maintaining at least one said at least one vent flap element open until at least one predetermined vent flap closing condition is met.

Optionally, the at least one predetermined vent flap closing condition comprises the condition that the engine temperature is less than a predetermined maximum vent flap closing temperature.

This feature has the advantage that the at least one vent flap may be prevented from closing if the engine is at a particularly high temperature or where portions of the engine are liable to increase in temperature due to the presence of a substantial amount of heat energy within one or more regions of the engine.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 is a schematic illustration of a vehicle engine having a heat retention structure according to an embodiment of the invention fitted thereto; FIGURE 2 is a schematic illustration of a top vent flap employed in the heat retention structure of the embodiment of FIG. 1; FIGURE 3 is a schematic illustration of a top vent flap for us in a heat retention structure according to a further embodiment of the invention; FIGURE 4 is a schematic illustration of the vehicle engine and heat retention structure of the embodiment of FIG. 1 as viewed from a front of the vehicle; and FIGURE 5 is a schematic illustration of a baffle arrangement for preventing flow of air from one side of the engine to the other with respect to a lateral vehicle axis.

DETAILED DESCRIPTION FIG. 1 is a schematic illustration of a front portion of a vehicle 100 according to an embodiment of the present invention in cross-sectional form as viewed in a transverse direction, i.e. with the vehicle viewed from one side (in the present illustration, a right side). The vehicle 100 has an engine compartment 120 covered by a bonnet (or hood) 103 and separated from a cabin of the vehicle by a cabin bulkhead 102. The engine compartment 120 houses an engine 121 having a head portion (or ‘head’) 121H, a block portion (or ‘block’) 121B and a sump portion (or ‘sump’) 121S. In the embodiment illustrated in FIG. 1 the engine 121 is located between a pair of front wheels 151 of the vehicle 100. The engine is provided with a turbocharger device 125, shown in dashed outline in FIG. 1. An undertray 145 is provided below the engine and spans a distance between a front bumper 104 and cabin bulkhead 102. The tray is discontinuous, allowing for flow or air downwardly out from the engine compartment 120.

The engine 121 is provided with an engine heat retention structure. The heat retention structure 130 has a thermal shell structure 130S substantially in the form of an inverted cup that encloses the head 121H and substantially the entire block 121B of the engine 121. The sump 121S of the engine 121 protrudes below a lower edge of the shell structure 130S in the embodiment shown. In some alternative embodiments the lower edge of the shell structure 130S may be substantially at or below a lower level of the sump 121S, the lower level being indicated by horizontal line S1 in FIG. 1. In the embodiment of FIG. 1 the thermal shell structure 130S may be said to have an upper or top portion 130T and a downwardly-directed skirt portion 130SS that projects downwardly from the top portion 130T. The downwardly-directed skirt portion 130SS has a lower edge 130SSE that defines an opening arranged to allow air to flow into and out from the heat retention structure. The downwardly-directed skirt portion 130SS extends from the top portion 130T to the lower edge 130SSE.

The vehicle 100 has a radiator pack 140 provided within the engine compartment 120 behind a front grille 105 of the vehicle 100. The front grille 105 has active grill shutters 105R that are pivotable between open and closed conditions in which they permit and block, respectively, a flow of ram air into the engine compartment 120 when the vehicle 100 travels in a forward direction. The active grill shutters 105R are caused to switch between the open and closed conditions by means of an actuator device under the control of a controller in a known manner.

The radiator pack 140 has a fan device 143 arranged to draw air through a radiator 141 and front grille 105 when the active grill shutters 105R are open. The fan device 143 blows the air rearward towards the thermal shell structure 130S.

Some of the air thrown rearward by the fan device 143 is deflected downwardly by the thermal shell structure 130S where a portion of the air enters an air velocity deflector 147. The air velocity deflector 147 directs the air under the lower edge 130SSE of the skirt portion 130SS of the thermal shell structure 130S and upwardly between the engine 121 and thermal shell structure 130S. Air drawn through the front grille 105 is thus introduced into the thermal shell structure 130S and forced in an upward direction between the engine block 121B and thermal shell structure 130S. Existing air within the thermal shell structure 130S is therefore displaced, being ultimately forced downwardly out from the thermal shell structure 130S.

In the embodiment of FIG. 1, the air velocity deflector 147 is in the form of a substantially closed conduit. In some alternative embodiments the scoop may be in the form of an open air-deflecting surface arranged to direct air from the front of the vehicle 100 upwardly into the thermal shell structure 130S. In some embodiments an air velocity deflector 147 may not be provided.

In the illustration of FIG. 1 air flow lines F1 are shown, illustrating the flow of air passing through the radiator grill 105 and air velocity deflector 147 in use.

It is to be understood that, in use, the engine 121 and thermal shell structure 130S, which is fixedly coupled to the engine 121, experience movement within the engine bay 120 such as a rocking movement during acceleration and deceleration. Whilst in some embodiments the air velocity deflector 147 could be coupled to the radiator pack 140 to increase the flow of air through the deflector 147, the fact that the engine 121, thermal shell structure and air velocity deflector 147 are decoupled from the radiator pack 140 in the present embodiment eliminates problems associated with direct coupling such as wear. In the present embodiment the air velocity deflector 147 is positioned such that a flow of air is maintained therethrough from the radiator pack 140, when the fan (or blower) device 143 is running, even at the extremes of movement of the engine 121 within the engine bay 120 in normal use.

In the embodiment of FIG. 1, engine sump 121S protrudes below the thermal shell structure 130S and is exposed to air flowing between the undertray 145 and thermal shell structure 130S.

In the embodiment shown, the sump 121 is provided with close-coupled thermal insulation thereover in the form of a sprayed-on foam insulation layer. Other forms of thermal insulation may be useful such as sheet-form insulation bonded to the sump by means of an adhesive, or attached thereto by means of mechanical fixing elements such as screws, bolts, clips or the like. In some embodiments thermal insulation is not provided in contact with the sump 121.

In the embodiment of FIG. 1 the thermal shell structure 130S is provided with six vent flaps 131, 133. Two of the vent flaps 131 are provided in a top or upper surface 130T of the shell structure 130S, the upper surface 130T being located diametrically opposite the opening defined by the lower edge 130SSE of the downwardly-directed skirt portion 130SS, and may be referred to as top vent flaps 131, whilst two vent flaps 133 are provided on left and right opposite sides of the shell structure 130S, on opposite sides of the skirt portion 130SS, at a depth of around one quarter of the height of the shell structure 130S below the upper surface 130T. These latter vent flaps 133 may be referred to as side vent flaps 133.

The vent flaps 131, 133 are provided at least in part to promote flow of air through the thermal shell structure 130S, particularly in respect of locations where the rate of air flow may have a tendency to be lower than in other places. Variations in air flow rate may occur for example due to a shape of the engine 121 and/or the thermal shell structure 130S. In the arrangement of FIG. 1, the top vent flaps 131 are arranged to promote flow of air over an upper surface of the engine 121, reducing the likelihood of ‘hot spots’ forming in that region. Vent flaps 131, 133 may in addition or instead be provided at or near locations that are sources of particularly large thermal loads, such as turbocharger devices 125 or the like.

It is to be understood that the number and location of vent flaps 131, 133 may be selected, for a given embodiment, according to the particular configuration of engine 121 and thermal shell structure 130S. Thus other numbers of flaps 133 at a given depth below the top of the shell structure 130S may also be useful such as one, three or more flaps at a given depth. The number of vent flaps 133 provided on each side may be different for different sides, particularly where shape effects or differences in thermal loading from one side to the other warrant additional vent flap 133 provision on one side compared with the other.

In the present embodiment the vent flaps are configured to assume an open or closed condition in dependence on the flow rate of air past the vent flaps 131, 133 within the thermal shell structure 130S. In the present embodiment, the vent flaps 131, 133 are provided with biasing means for biasing the vent flaps to the closed condition. The vent flaps 131, 133 are each arranged such that, when the flow rate of air past a given vent flap 131, 133 reaches or exceeds a predetermined value, a force on the vent flap 131, 133 due to the air flow is sufficient to overcome the biasing force of the biasing means that tends to close the vent flap 131, 133, resulting in opening of the vent flap 131,133. FIG. 2 is a schematic illustration of a top vent flap 131 according to the embodiment of FIG. 1.

In the arrangement of FIG. 2 the vent flap 131 is coupled to the shell structure 130S by means of a pivot element 131 of the vent flap 131 that allows pivoting of a flap element 131F and paddle element 131A of the vent flap 131 about an axis that lies substantially in the plane of an outer surface of the shell structure 130S and is aligned along a line defining a transverse section (or slice) through the shell structure 130S.

The vent flap 131 is arranged, in a closed condition (the position of the flap element 131F and paddle element 131A in the closed condition being shown in solid outline), to substantially close an air exit aperture 130A formed in the shell structure 130S, through which air that has been forced to pass between the engine 121 and shell structure 130S may exit the volume enclosed by the shell structure 130S.

The pivot element 131P of the vent flap 131 is provided forward of a position midway between a leading edge 130AL and a trailing edge 130AT of the air exit aperture 130A. In the embodiment of FIG. 2 the pivot element 131P is provided at a position that is substantially one third of the distance from the leading edge 130AL of the air exit aperture 130A to the trailing edge 130AT. Providing the pivot element 131P (and therefore the pivot point of the vent flap 131) at this location results in a net torque on the flap element 131F and paddle element 131A that biases the flap element 131F to the position shown in solid outline in FIG. 2, i.e. the closed condition of the vent flap 131.

The flap element 131F and paddle element 131A are integrally formed from a single plate of aluminium in the present embodiment. When the vent flap 131 is in the closed condition, the flap element 131F substantially covers the portion of the air exit aperture 130A between the pivot element 131P and trailing edge 130AT of the air vent exit aperture 130A. Similarly, the paddle element 131A projects forward of the pivot element 131P to cover the portion of the air exit aperture 130A between the pivot element 131P and leading edge 131AL of the air exit aperture 130A, before turning inwardly towards the engine 121 and into the volume between the shell structure 130S and engine 121.

As noted above, in the embodiment of FIG. 2 the vent flap element 131F and paddle element 131A are formed from a single sheet of aluminium. Other materials may be useful in some embodiments such as a plastics material, other metal material, or any other suitable material.

In the embodiment of FIG. 2, the top vent flaps 131 are biased to the closed condition under gravity, the length (and weight) of the flap element 131F being greater than that of the paddle element 131 A. In some embodiments, additional biasing means may be provided for biasing the top vent flaps 131 to the closed condition. In some embodiments the additional biasing means may be in the form of a spring element such as a helical spring element, leaf spring element or any other suitable biasing means.

As illustrated in FIG. 2, in use, when air is forced through the shell structure between the engine 121 and shell structure 130S, the force F of air impinging on the paddle portion 131A of the top vent flap 131, which is arranged to present a major face thereof transversely to the flow of air thereon, causes a torque T to be applied to cause rotation of the flap element 131F and paddle portion 131A against the action of gravity to an open condition. This allows air to flow out from the shell structure 130S, enhancing flow of air through the shell structure 130S.

The positions of the flap element 131F and paddle portion 131A when the vent flap 131 is in the open condition are shown in dashed outline in FIG. 2, the flap element being shown at 131F’ and the paddle portion at 131 A’.

It is to be understood that, in the case of side vent flaps 133, a similar design to that of the top vent flaps 131 of FIG. 2 may be employed with the optional addition of biasing means for promoting closure of the side vent flaps 133. The biasing means may for example be in the form of spring elements, such as helical spring elements, coupled to the flap element 131F and/or paddle portion 131 A. An example of such biasing means in the form of a helical coil spring element 131B” is shown in dashed outline, the element 131B” being coupled at opposed ends to the paddle portion 131A and shell structure 130S, respectively, and arranged to promote closure of the vent flap 131 by pulling on the paddle portion 131 A. FIG. 3 is a schematic illustration of a top vent flap 231 according to a further embodiment of the invention. Like features of the flap 231 of FIG. 3 to those of the flap 131 of FIG. 2 are shown with like reference signs incremented by 100.

In a similar manner to the embodiment of FIG. 2, in the embodiment of FIG. 3 the vent flap 231 is coupled to the shell structure 230 by means of a pivot element 231 of the vent flap 231. The pivot element 231 allows pivoting of a flap element 231F and paddle element 231A of the vent flap 231 about an axis that lies substantially in the plane of an outer surface of the shell structure 230 and is aligned along a line defining a transverse section through the shell structure 230. The flap element 231F is arranged to substantially cover air exit aperture 230A formed in the shell structure 230, through which air that has been forced to pass between the engine 221 and shell structure 230 may exit the volume enclosed by the shell structure 230. The paddle element 231A is fixedly coupled to the flap element 231F and provided substantially orthogonal thereto.

The paddle element 231A projects inwardly into the volume between the shell structure 230 and engine 221 when the vent flap 231 is in the closed condition. It is to be understood that both the flap element 231F and paddle element 231A are in the form of substantially flat plates or sheets. In the embodiment of FIG. 3 the vent flap element 231F and paddle element 231A are formed from aluminium. Other materials may be useful in some embodiments such as a plastics material, other metal material, or any other suitable material. In some embodiments the paddle element 231A and flap element 231F are integrally formed from a single piece of material.

Biasing means 231B is provided in the form of a helical coil spring element 231B that is coupled at opposite ends thereof to the paddle element 231A and shell structure 230, respectively, and arranged to bias the vent flap 231 to the closed condition.

As illustrated in FIG. 3, in use, when air is forced through the shell structure between the engine 221 and shell structure 230, the force F of air impinging on the paddle portion 231 A, which is arranged to present a major face thereof transversely to the flow of air between the engine 121 and shell structure 230 when in the closed condition, causes a torque T to be applied to deflect the vent flap 231 against the biasing force of the spring element 231B to an open condition. This allows air to flow out from the shell structure 230, enhancing flow of air through the shell structure 230.

In the embodiment of FIG. 1, an air velocity deflector 147 that is separate from the radiator air duct 145 is provided that is arranged to direct air flowing under the vehicle 100 below the front grille 105 upwardly and into the thermal shell structure 130S, again displacing downwardly air already contained within the thermal shell structure 130S. It is to be understood that the air velocity deflector 147 provides additional air flow over the engine 121 between the engine 121 and thermal shell structure 130S when the vehicle 100 is moving in a forward direction. In some embodiments an air velocity deflector 147 may not be provided.

In the illustration of FIG. 1 air flow lines F1 shown, illustrating the flow of air passing through the front grill 105 and air velocity deflector 147 in use. It can be seen that some air flowing through an upper region of the thermal shell structure 130S flows out from the thermal shell structure 130S through either the top vent flaps 131 or side vent flaps 133, and out from the engine compartment 120 through an air vent aperture 103A provided between the bonnet 103 and cabin bulkhead 102.

In the embodiment of FIG. 1, engine sump 121S protrudes below the thermal shell structure 130S and is exposed to air flowing below the vehicle 100. In the embodiment shown, the sump 121 is provided with close-coupled thermal insulation thereover in the form of a sprayed-on foam insulation layer. Other forms of thermal insulation may be useful such as sheet-form insulation bonded to the sump by means of an adhesive, or attached thereto by means of mechanical fixing elements such as screws, bolts, clips or the like. FIG. 4 is a sectional view of the engine 121 and thermal shell structure 130S as viewed from a front of the vehicle, other components such as the front grille 105 and bonnet 103 being omitted for clarity.

In some embodiments, one or more fan devices may be provided for directing air into the thermal shell structure 130S substantially directly and not via the radiator pack 140.

It is to be understood that, in the present embodiment, the flow rate of air through the deflector 147 and up within the thermal shell structure 130S may be controlled at least in part by means of the active grill shutters 105R of the front grille 105 (open or closed) and the state of the fan device 143 (on or off).

In the present embodiment, controller 100C is provided for controlling the state of the fan device (switching it on or off) and the state of the active grill shutters 105R (causing them to open and close). The controller 100C monitors the temperature of the engine 121 by means of a temperature sensor 121 SR. When the temperature exceeds a first predetermined temperature the controller 100C causes the active grill shutters 105R to open. In the present embodiment the first predetermined temperature is in the range from around 80-90C. If the temperature exceeds a second predetermined temperature the controller 100C causes the fan device 143 to switch on in addition to maintaining the active grill shutters 105R in the open condition.

In some embodiments, one or more baffles or other wall-like structures may be provided for controlling the direction of flow of air between the engine 121 and thermal shell structure 130S. FIG. 5 is a schematic illustration of an engine 321 provided with a thermal shell structure 330S according to a further embodiment of the present invention. Like features of the embodiment of FIG. 5 to those of the embodiment of FIG. 1 are shown with like reference signs incremented by 200. The embodiment of FIG. 5 has top and side vent flaps 331,333 in a similar manner to the embodiment of FIG. 1. In the embodiment of FIG. 5, the thermal shell structure 330S has a baffle portion 330B that forms a wall, partially dividing the internal volume of the thermal shell structure 330S into two halves. The baffle portion 330B may also be described as an internal fin or finned portion 330B. The baffle portion 330B is arranged to substantially span an air gap between the thermal shell structure 330 and engine block 321B such that a left half of the engine block 321B (with the vehicle viewed from behind) is exposed to air flowing within the thermal shell structure 330S on the left side of the baffle portion 330B and a right half of the engine block 321B is exposed to air flowing within the thermal shell structure 330S on the right side of the baffle portion 330B. The embodiment of FIG. 5 has the advantage that a greater flow rate of air between the engine block 321B and thermal shell structure 330S may be achieved since turbulent flow within the thermal shell structure 330S may be substantially prevented.

In the embodiment of FIG. 5 the top vent flaps 331 are arranged to over lie the baffle portion 330B such that the baffle portion 330B substantially bisects the top vent flaps 331 as viewed from above. The arrangement is such that, when the top vent flaps 331 are open, air is able to flow out from within the shell structure from both the left and right sides of the baffle portion 330B.

In some alternative embodiments, at least one top vent flap 331 may be provided at a location to the left of the baffle portion 330B as viewed from a front of the shell structure as in FIG. 5(a), so as to exhaust only air flowing over the right-hand surface of the engine 121 (with the vehicle viewed from behind) and at least one top vent flap 331 may be provided at a location to the right of the baffle portion 330B as viewed from a front of the shell structure as in in FIG. 5(a), so as to exhaust only air flowing over the left-hand side of the engine 121 (with the vehicle viewed from behind).

It is to be understood that other baffle arrangements may be useful in some embodiments. For example, in some embodiments at least a further two baffle portions may be provided, such that air flow between the engine block 321B and thermal shell structure 330 is constrained within one of four channels defined between the engine block 321B and thermal shell structure 330.

In some embodiments, one or more vent flaps 131, 133, 231, 331,333 may be configured to be opened or closed by means of one or more actuators under the control of a controller 100C. The flaps may be arranged to be opened when a predetermined vent flap opening condition is met. In one embodiment, the condition may comprise the requirement that the engine is running and the temperature of the engine is not less than a predetermined minimum vent flap opening temperature. The actuator may be any suitable actuator such as an electric motor, solenoid device or any other suitable actuator.

Similarly, the one or more vent flaps 131,133, 231,331,333 may be configured to be closed when at least one predetermined vent flap closing condition is met. In one embodiment, the condition comprises the requirement that the engine temperature is less than a predetermined maximum vent flap closing temperature. In some embodiments, closure of the one or more vent flaps may take place after the engine 121 has been shut down.

Other arrangements may be useful in some embodiments.

It will be understood that the embodiments described above are given by way of example only and are not intended to limit the invention, the scope of which is defined in the appended claims.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS:

1. An engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine in use, the shell being arranged to be provided in a spaced apart relationship with the engine thereby to allow circulation of air between the shell and engine, the shell comprising an open skirt portion arranged to allow air to flow into and out from the heat retention structure between the engine and shell, the heat retention structure being provided with at least one vent flap element through which air may flow out from the heat retention structure in dependence on whether the at least one vent flap element is in an open condition or a closed condition.

2. A structure according to claim 1 wherein the open skirt portion comprises a first edge that defines an opening arranged to allow air to flow into and out from the heat retention structure.

3. A structure according to claim 2 wherein the shell comprises a first surface located diametrically opposite the opening defined by the first edge of the open skirt portion.

4. A structure according to claim 3 wherein the at least one vent flap element is located closer to the first surface of the shell than the first edge of the open skirt portion.

5. A structure according to claim 3 wherein at least one vent flap element is located on the first surface of the shell.

6. A structure according to claim 4 wherein at least one vent flap element is located on the open skirt portion.

7. A structure according to any preceding claim wherein the at least one vent flap element is arranged to open automatically and close automatically in dependence at least in part on the flow rate of air on an inside of the thermal shell between the engine and thermal shell in use.

8. A structure according to any preceding claim wherein the at least one vent flap element comprises a flap portion pivotable about an axis between a closed position and an open position and a paddle portion, the paddle portion being exposed to air flow on an inside of the shell in use, wherein the flap portion may be caused to pivot reversibly between the closed and open positions in dependence at least in part on a force imposed on the paddle portion due to air flow within the thermal shell.

9. A structure according to claim 8 wherein the at least one vent flap element comprises biasing means arranged to bias the flap portion to the closed position.

10. A structure according to claim 9 wherein the biasing means comprises a counterweight arrangement whereby the flap portion is biased to the closed position under gravity.

11. A structure according to any preceding claim further comprising at least one baffle portion comprising a wall arranged to span a gap between the thermal shell and engine, the baffle portion being arranged to substantially prevent flow of air there past in use.

12. A structure according to claim 11 wherein the wall of the at least one baffle portion is arranged in a substantially vertical orientation.

13. A structure according to claim 11 or claim 12 wherein the baffle portion is arranged to at least partially restrict flow of air from one side of the engine to an opposite side in use.

14. A structure according to any preceding claim in combination with an air velocity deflector portion configured to direct air into the heat retention structure between the engine and thermal shell in use.

15. A structure according to claim 14 wherein the air velocity deflector portion comprises an air duct configured to direct air into the heat retention structure between the engine and thermal shell in use.

16. A structure according to any preceding claim in combination with an air blower device configured to direct air into the heat retention structure between the engine and thermal shell.

17. A structure according to any preceding claim comprising at least one actuator for opening and closing at least one said at least one vent flap.

18. A structure according to any preceding claim wherein the open skirt portion is downwardly directed, in use, and arranged in use to at least partially surround the engine.

19. A structure according to any preceding claim in combination with an engine.

20. A motor vehicle comprising an engine provided with an engine heat retention structure according to any one of claims 1 to 13.

21. A motor vehicle according to claim 20 as depending through claim 14 further comprising a radiator pack comprising a radiator and air blower device, the air blower device being arranged in use to direct air towards the air velocity deflector portion such that the air flows into the thermal shell.

22. A motor vehicle according to claim 21 wherein the air velocity deflector portion is arranged to direct air that has passed over or through the radiator device into the thermal shell from below the thermal shell.

23. A method of heat retention comprising providing an engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine in use, the shell being arranged to be provided in a spaced apart relationship with the engine thereby to allow circulation of air between the shell and engine, the shell comprising an open skirt portion, the method comprising allowing air to flow into and out from the heat retention structure via the open skirt portion of the thermal shell, the method comprising allowing air to flow out from the heat retention structure via at least one vent flap element in dependence on whether the at least one vent flap element is in an open condition or a closed condition.

24. A method according to claim 23 comprising, following an engine start, maintaining at least one said at least one vent flap element closed until at least one predetermined vent flap opening condition is met.

25. A method according to claim 24 wherein the at least one predetermined vent flap opening condition comprises the condition that the engine temperature is not less than a predetermined minimum vent flap opening temperature.

26. A method according to any one of claims 23 to 25 comprising, following an engine shutdown, maintaining at least one said at least one vent flap element open until at least one predetermined vent flap closing condition is met.

27. A method according to claim 26 wherein the at least one predetermined vent flap closing condition comprises the condition that the engine temperature is less than a predetermined maximum vent flap closing temperature.