GB2562223A

GB2562223A - Heat retention structure and method

Info

Publication number: GB2562223A
Application number: GB1707306.5A
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: GB201707306D0; GB2562223B

Abstract

An engine heat retention structure 130 which comprises a thermal shell 130S which at least partially encapsulates an engine 121. The shell is spaces away from the engine to allow air to circulate between them. The shell comprises a skirt portion 130SS downwardly directed. Air flow is prevented out of the structure the top of the structure and the skirt portion allows air to flow upwardly or downwardly. A deflector 147or fan 143 for directing air into the structure may be provided. The structure prevents heat loss from the engine, for example when parked. The efficiency of the engine is improved as it is dependent on the viscosity of oil (thus temperature). By maintaining heat normal operating temperature is reached quickly following cold starts. An engine with such a heat retainer, vehicle using such an engine and method of retaining heat are also disclosed.

Description

HEAT RETENTION STRUCTURE AND METHOD

FIELD OFTHE 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 one 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, 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 substantially downwardly directed in use and arranged to at least partially surround the engine, the structure being arranged to substantially prevent flow of air out from the structure above a predetermined depth below an upper surface of the engine, the skirt portion being arranged to allow air to flow upwardly or downwardly into and out from the heat retention structure between the engine and shell.

Embodiments of the present invention have the feature that air surrounding the engine within the thermal shell that becomes heated by the engine will remain trapped within the shell unless air is forced upwardly into the thermal shell due to movement of the vehicle or the action of an electric blower (or fan device), as discussed below. Similarly, air can escape from the shell by passing below the predetermined depth below the upper surface of the engine block. However, 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 at a level above the predetermined depth remains substantially trapped within the volume defined by the shell. It is to be understood that this is due to the greater buoyancy of air warmed by the engine relative to ambient air.

Thus 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. Whilst when the engine is switched off, relatively warm ambient air may be trapped between the engine and shell, reducing the rate of cooling of the engine. It is to be understood that, by reducing the rate of cooling of the engine, higher engine start-up temperatures may be enjoyed, depending on the time for which the engine remains switched off. Higher engine startup temperatures reduce losses associated with higher oil viscosity. Higher engine temperatures at start-up may also increase the rate at which an engine after-treatment system warms to its normal operating temperature.

The structure may be configured to be provided within an engine bay of a motor vehicle. The structure may be provided within the engine bay of a motor vehicle.

Optionally the predetermined depth corresponds to at least substantially half the height of the engine block.

That is, at least substantially half of the engine block is above the predetermined level.

Optionally, the structure is arranged to substantially prevent flow of air out from the structure above the lower edge of the skirt portion.

In other words, the predetermined depth below the upper surface of the engine block corresponds substantially to the depth of the skirt portion.

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

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.

The structure may be provided in combination with an air velocity deflector portion comprising an air duct configured to direct air into the heat retention structure between the engine and thermal shell substantially at the predetermined depth.

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.

Optionally, the air blower device is configured to direct air into the air duct of the air velocity deflector portion.

The structure may further 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.

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.

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.

The structure may be configured to be provided within an engine bay of a motor vehicle beneath a bonnet of the vehicle.

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

In a still further 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 according to claim to another aspect, the engine and heat retention structure being provided within an engine bay of the vehicle beneath a bonnet of the vehicle.

In one 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, 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 a substantially downwardly directed open skirt portion arranged to at least partially surround the engine, the structure being arranged to substantially prevent flow of air out from the structure above a predetermined depth below an upper surface of the engine, the method comprising causing a flow of air upwardly into the heat retention structure between the engine and shell portion via the skirt portion whereby a corresponding flow of air is generated out from the heat retention structure.

In an embodiment there is provided an engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine, 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 a substantially downwardly directed open skirt portion arranged to substantially surround an engine block of the engine, the structure being arranged to substantially prevent flow of air out from the structure above a predetermined depth below an upper surface of the engine block, the skirt portion being arranged to allow air to flow upwardly or downwardly into and out from the heat retention structure between the engine and shell.

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 the vehicle engine and heat retention structure of the embodiment of FIG. 1 as viewed from a front of the vehicle; FIGURE 3 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; FIGURE 4 is (a) a schematic perspective view of a portion of a vehicle according to an embodiment of the present invention showing a front face of a thermal shell structure and an air velocity deflector attached to the structure, and (b) a cross-section along A-A at a plane normal to the front face of the thermal shell structure and including a full section of the air velocity deflector intersected by the plane; and FIGURE 5 is a schematic illustration of a thermal shell structure according to a further embodiment of the invention.

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 130 having 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 130S that projects downwardly from the top portion 130T.

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 (or blower) 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 130. In the present embodiment the fan device 143 is electrically powered although in some embodiments the device 143 may be engine driven.

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 duct or conduit. In some alternative embodiments the deflector 147 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. The deflector 147 may be referred to as a scoop in some embodiments. In some embodiments an air velocity deflector 147 may not be provided.

In the illustration of FIG. 1 air flow lines F 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 130, whch 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 blower device 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 130 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. FIG. 2 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 121SR. 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. 3 is a schematic illustration of an engine 221 provided with a thermal shell structure 230S according to a further embodiment of the present invention. Like features of the embodiment of FIG. 3 to those of the embodiment of FIG. 1 are shown with like reference signs incremented by 100. In the embodiment of FIG. 3, the thermal shell structure 230S has a baffle portion 230B that forms a wall, partially dividing the internal volume of the thermal shell structure 230S into two halves. The baffle portion 230B may also be described as an internal fin or finned portion 230B. The baffle portion 230B is arranged to substantially span an air gap between the thermal shell structure 230S and engine block 221B such that a left half of the engine block 221B (with the vehicle viewed from behind) is exposed to air flowing within the thermal shell structure 230S on the left side of the baffle portion 230B and a right half of the engine block 221B is exposed to air flowing within the thermal shell structure 230S on the right side of the baffle portion 230B. The embodiment of FIG. 3 has the advantage that a greater flow rate of air between the engine block 221B and thermal shell structure 230S may be achieved since turbulent flow within the thermal shell structure 230S may be substantially prevented

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 221B and thermal shell structure 230S is constrained within one of four channels defined between the engine block 221B and thermal shell structure 230S. FIG. 4 illustrates a portion of a thermal shell structure 330S according to a further embodiment of the invention. Like features of the embodiment of FIG. 4 to those of the embodiment of FIG. 3 are shown with like reference signs incremented by 100.

The shell structure of the embodiment of FIG. 4 is similar to that of the embodiment of FIG. 3 with the addition of an air velocity deflector 347. FIG. 4(a) is a perspective view of a front portion of the thermal shell structure 330S showing front face 330F and air velocity deflector 347 attached to the structure 330. FIG. 4(b) shows a cross-section along A-A at a plane normal to the front face 330 and including a full section of the air velocity deflector 347 intersected by the plane. It can be seen that the air velocity deflector 347 is in the form of a trough that sits substantially directly below the front face 330F of the thermal shell structure 330 and serves to direct air that enters the deflector 347 under the front face 330F and upwardly into the thermal shell structure 330. FIG. 5 shows a thermal shell structure 430S of a heat retention structure 430 according to a further embodiment of the invention. Like features of the shell structure of the embodiment of FIG. 5 to those of the embodiment of FIG. 4 are shown with like reference signs incremented by 100.

The embodiment of FIG. 5 has an air velocity deflector 447 attached to the thermal shell structure 330S and has a similar design to that of the embodiment of FIG. 4. The embodiment of FIG. 4 differs from that of FIG. 5 in that the air velocity deflector 447 is arranged to cause air to flow into the skirt portion 430SS through an aperture 430SSA formed in a front face 430F of the shell structure 430S.

As in the case of the embodiment of FIG. 4, the air velocity deflector 447 serves to direct air that enters the deflector 447 upwardly into the thermal shell structure 430. As shown in dotted outline in FIG. 5, the deflector 447 has a substantially semicircular cross-section (as shown in FIG. 4(b) with respect to the embodiment of FIG. 4) in order to so direct the flow of air.

It is to be understood that, when a vehicle fitted with the heat retention structure 430 of FIG. 5 is stationary with the engine switched off, air warmed by the engine 121 and any associated components encapsulated by the shell structure 430S will tend to remain trapped within the shell structure unless a path of escape exists. In the embodiment of FIG. 4, trapped air can escape substantially only by passing under the lower edge of the skirt portion 330SS. In contrast, in the embodiment of FIG. 5 trapped air can escape through the aperture 430SSA associated with the deflector 447. Thus, air substantially at or above the level of aperture 430SSA, i.e. at or above notional line 430SL shown in FIG. 5, may remain trapped whilst air below this level may tend to escape through the aperture 447. The line 430SL may be considered to be at a predetermined depth D below an upper level of engine block 121B, to which head 121H is attached. Other definitions of the location of line 430SL may be useful in some embodiments. It is to be understood that the shell structure 130S is thus arranged to substantially prevent flow of air that is located above predetermined depth D below the upper surface of the engine block 121B out from the structure 130SS.

It is to be understood that, in use, air within the shell structure 430S below the level of line 430SL will tend to cool more quickly than air above the level of line 430SL. Thus, in some embodiments, with a relative cold ambient outside air temperature the temperature of air within the thermal shell structure below the line 430SL may cool to a temperature of 14C whilst air above the line 430SL is at a temperature of at or above (say) 40C.

In the embodiment shown in FIG. 5, the depth D is substantially 75% of the overall height of the engine block 121B, i.e. the portion of the engine between sump 121S and head 121H. This corresponds to approximately 75% of the overall height of the engine 121. Other values of depth D may be useful such as 80%, 90% or substantially 100% of the height of the engine block 121B. The depth D may be more than 100% or less than 75% in some alternative embodiments.

It is to be understood that a thermal shell 130S according to an embodiment of the invention may itself have a lower edge 130SSE to the skirt portion 13SS that is any suitable depth (distance) below the top of the engine block 121B such as 50%, 75%, 80, 90%, 100%, 110%, 120% or any other suitable depth.

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, 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 substantially downwardly directed in use and arranged to at least partially surround the engine, the structure being arranged to substantially prevent flow of air out from the structure above a predetermined depth below an upper surface of the engine, the skirt portion being arranged to allow air to flow upwardly or downwardly into and out from the heat retention structure between the engine and shell.

2. A structure according to claim 1 wherein the predetermined depth corresponds to at least substantially half the height of the engine.

3. A structure according to claim 1 or claim 2 wherein the structure is arranged to substantially prevent flow of air out from the structure above the lower edge of the skirt portion.

4. 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.

5. A structure according to claim 4 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.

6. A structure according to claim 2 claim in combination with an air velocity deflector portion comprising an air duct configured to direct air into the heat retention structure between the engine and thermal shell substantially at the predetermined depth.

7. 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.

8. A structure according to claim 7 as depending through any one of claims 5 or 6 wherein the air blower device is configured to direct air into the air duct of the air velocity deflector portion.

9. 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.

10. A structure according to claim 9 wherein the wall of the at least one baffle portion is arranged in a substantially vertical orientation.

11. A structure according to claim 9 or claim 10 wherein the baffle portion is arranged to at least partially restrict flow of air from one side of the engine to an opposite side.

12. A structure according to any preceding claim configured to be provided within an engine bay of a motor vehicle beneath a bonnet of the vehicle.

13. An engine provided with an engine heat retention structure according to any preceding claim.

14. A motor vehicle comprising an engine provided with an engine heat retention structure according to claim 13, the engine and heat retention structure being provided within an engine bay of the vehicle beneath a bonnet of the vehicle.

15. A method of heat retention comprising providing an engine heat retention structure comprising a thermal shell arranged to at least partially encapsulate an engine, 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 a substantially downwardly directed open skirt portion arranged to at least partially surround the engine, the structure being arranged to substantially prevent flow of air out from the structure above a predetermined depth below an upper surface of the engine, the method comprising causing a flow of air upwardly into the heat retention structure between the engine and shell portion via the skirt portion whereby a corresponding flow of air is generated out from the heat retention structure.