TECHNICAL FIELD

The present invention generally relates to an airflow control system for controlling heat transfer in a motor vehicle. Aspects of the invention relate to a spoiler, to a controller for actuating an airflow control element and to a vehicle.

BACKGROUND OF THE INVENTION

It is generally very difficult to drive airflow through apertures on the rear of a moving vehicle since the pressure differences are usually very small. Flow structures like the front wheel wakes, A-post vortices and mirror wakes lower the total pressure of air entering cooling apertures at the rear of the car. There is also an additional problem created by boundary layer growth on body panels. Airflow entering cooling apertures at the rear will usually have a thick boundary layer as a result of air travelling along the surface of large body panels. This reduces available total pressure in the cooling duct and presents particular problems in providing effective cooling for a vehicle having a propulsion system and associated heat exchangers mounted at the rear.

Conventionally, heat exchangers are mounted on the front of a vehicle where higher pressure airflow can be forced through the devices to lower pressure regions. These devices are usually mounted up-stream of flow structures like wheel wakes, mirror wakes, vortices etc. Hence the total pressure head available does not typically suffer any degradation (unless there is flow separation inside ducts). However, generating the required pressure differential to drive air through a cooling pack at the rear of a vehicle is challenging.

The present invention sets out to overcome or ameliorate at least some of the problems associated with prior art arrangements.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a system, to a device, to a motor vehicle and to a controller as claimed in the appended claims. According to an aspect of the invention there is provided an aerodynamic device for a vehicle being movable between stowed and deployed positions and being arranged such that in at least the deployed position, the aerodynamic device generates a low pressure region close to an outlet of a heat transfer apparatus so as to increase airflow through said apparatus.

l The aerodynamic device may comprise, without limitation, a wing or spoiler arranged to influence airflow over or around the vehicle, for example to increase downforce and/or drag on the vehicle in one or both of the stowed and deployed positions. According to a further aspect of the invention there is provided an airflow control system for controlling heat transfer in a motor vehicle, the airflow control system comprising:

a heat transfer chamber in fluid communication with a first inlet and a first outlet; wherein a flow control element is provided proximal said first outlet for controlling the flow of air from the heat transfer chamber through said first outlet.

In a further aspect, the present invention relates to an airflow control system for controlling heat transfer in a motor vehicle, the airflow control system comprising:

a heat transfer chamber in fluid communication with a first inlet and a first outlet; wherein a flow control element is provided proximal said first outlet for controlling the flow of air from the heat transfer chamber through said first outlet. By controlling the airflow through the first outlet, the flow control element can control cooling within the heat transfer chamber. The flow control element can be configured to establish a pressure differential between the air downstream of the first outlet and the air within the heat transfer chamber to control the airflow exiting through the first outlet. By lowering the downstream pressure relative to the pressure within the chamber, the airflow through the first outlet can be increased.

The flow control element can be operable to create a region having a lower pressure than the pressure within the heat transfer chamber. Thus, a localised pressure differential can be created to promote airflow from the heat transfer chamber through the first outlet. The flow control element could be positioned within the first outlet. Alternatively, the flow control element can be positioned downstream of the first outlet. The flow control element can be positioned in the incident airflow around the vehicle. The flow control element can be configured to accelerate airflow travelling over a surface arranged proximal to said first outlet. The flow control element can thereby reduce the air pressure at the first outlet for entraining air from the chamber. The flow control element can have an aerofoil section for improved efficiency.

The use of a flow control element to establish a region of low pressure proximal the air outlet to control flow is believed to be patentable independently. In a further aspect, the present invention relates to an airflow control system for a motor vehicle, the airflow control system comprising: a first inlet and a first outlet;

wherein a flow control element is provided proximal said first outlet for establishing a region of low pressure proximal said first outlet to control the flow of air through said first outlet. In use, the flow control element can establish a region of low pressure air adjacent to the first outlet to control the flow of air exiting through the first outlet. The flow control element can have a pressure side and a suction side. The suction side of the flow control element can face the first outlet and the pressure side of the flow control element can face away from the first outlet. A vehicle system requiring cooling (such as a heat exchanger, an electric drive motor, an internal combustion engine, an intercooler or a vehicle braking system) can be provided in a flow path between the first inlet and the first outlet.

The first inlet and the first outlet could be formed in a single duct. Alternatively, the first inlet could be formed in a first duct and the first outlet could be formed in a second duct. A heat transfer chamber could be provided in fluid communication with the first inlet and the first outlet. The heat transfer chamber could be in fluid communication with the first and second ducts.

The flow control element can be fixedly mounted relative to the first outlet. Alternatively, the flow control element can be movably mounted. The flow control element can be configured to provide active control of the airflow exiting the chamber. For example, the flow control element can be moved to alter the position and/or magnitude of a lower pressure region relative to the first outlet. The flow control element can undergo translation and/or rotation relative to the first outlet. The flow control element could, for example, pivot relative to the first outlet. The flow control element could be movable forwards and backwards relative to the first outlet; and/or upwards and downwards relative to the first outlet. At least one actuator can be provided for translating and/or rotating the flow control element.

The flow control element can be moved to multiple positions, at least one of which is arranged to pull air through the heat transfer chamber, for example to provide cooling of a heat exchanger provided therein.

The flow control element can be movable to open and close the first outlet. The flow control element can be displaced to close the first outlet and thereby inhibit the flow of air through the first outlet. The flow control element can move, through translation and/or rotation, to open the first outlet and thereby permit the flow of air through the first outlet. The flow control element can thereby uncover an exit path for airflow leaving the chamber. The flow control element can be movable between a first position and a second position. The first position can be a stowed position and the second position can be a deployed position. The flow control element can be substantially flush with an adjacent vehicle body panel(s) when in said stowed position. The flow control element can project into the airflow when in said deployed position. The flow control element can be inclined at an angle relative to the incident airflow. The flow control element can have a negative angle of attack relative to the incident airflow. The flow control element can thereby establish a reduced or negative static pressure on its suction side (the lower surface) which can help to 'pull' air through this exit path. The flow control element can be arranged in said deployed position at least partially to align the external air flow over the vehicle with a flow direction of air exiting the chamber through the first outlet.

The flow control element can be displaced outwardly from the first outlet as it moves from said stowed position to said deployed position. This displacement of the flow control element can create a fluid pathway between the flow control element and the first outlet.

The first outlet can be provided directly from the heat transfer chamber; or an outlet duct could be provided to connect the heat transfer chamber to the first outlet. The first outlet can be provided on an upper surface of the vehicle. The flow control element can be positioned above the first outlet. The flow control element can be configured to generate a down force on the motor vehicle when in said deployed position. The flow control element could also be displaced to an over-deployed position for providing an aero-braking function. The flow control element can have a negative angle of attack relative to the incident airflow when it is in said deployed position.

A controller can be provided for controlling the position and/or orientation of the flow control element. The controller can be configured to control the flow control element to control an operating temperature of a vehicle system. The controller can, for example, actuate the flow control element when a measured or calculated operating temperature reaches a threshold value. Alternatively, the controller can actuate the flow control element when a vehicle operating parameter, such as engine speed or vehicle speed, reaches a threshold value.

The flow control element can be provided at the rear of the vehicle. The flow control element can comprise a rear wing of the vehicle. The flow control element can be a spoiler provided at the back of the vehicle. Alternatively, the flow control element can be provided adjacent to a rearward-facing surface, such as a trailing edge of a vehicle roof, an engine cover, a rear deck or a rear panel. A second inlet can be provided also in fluid communication with said heat transfer chamber. The first and second inlets can be provided on respective sides of the motor vehicle. The first and second inlets can be provided on the flanks of the motor vehicle above the rear wheels.

The first inlet can be a dedicated air intake provided on an exterior of the vehicle. A duct can be provided for placing the first inlet in fluid communication with the heat transfer chamber. The duct can be bifurcated and comprise at least first and second branches. The heat transfer chamber could be formed integrally with the duct, for example formed along a section of the duct. Alternatively, the heat transfer chamber can be separate from the duct, for example a separate compartment.

The heat transfer chamber can comprise at least a second outlet. The second outlet can remain open to atmosphere continuously irrespective of the position of the flow control element. The second outlet can be provided at the rear of the vehicle.

The present invention also relates to a motor vehicle having an airflow control system as described herein. The heat transfer chamber can be provided at the rear of the vehicle. For example, the heat transfer chamber can be provided aft of an engine bay for accommodating a mid- or rear-engine configuration. A heat exchanger, or part thereof, can be provided in said heat transfer chamber. The heat exchanger can be associated with a vehicle propulsion system comprising an internal combustion engine or an electric drive motor. The heat exchanger can transfer heat from an electric drive system, for example from a battery pack and/or control electronics for an electric drive motor.

The airflow control system can be configured to provide cooling of a vehicle braking system comprising a brake disc and brake calliper. The vehicle braking system could be arranged at least partially inside or in fluid communication with a heat transfer chamber or duct of the type described herein. The first inlet could be a wheel arch or other aperture provided in the vehicle. The flow control element could be operated to control the flow of air over the vehicle braking system to provide cooling. The flow control element could be operated in response to a measured or calculated brake temperature. The flow control element could be deployable to an aero-braking position to generate a braking force and also to increase the airflow over the vehicle braking system. In a further aspect, the present invention can relate to a controller configured to actuate an active flow control element to control cooling of a vehicle system, the controller being configured to alter the position and/or angle of the flow control element in response to the temperature of the vehicle system. The flow control element can be an aerofoil. The operating temperature can be measured or calculated. The operating temperature can be the temperature of a battery pack for an electric drive system. The vehicle system can be a heat exchanger.

The present invention also relates to a controller of the type described herein in combination with an airflow control element.

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. For example, features described with reference to one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figures 1 A and 1 B show perspective front and rear views of a vehicle incorporating an airflow control system in accordance with an embodiment of the present invention;

Figure 2 shows a perspective rear view of the vehicle with a rear wing of the airflow control system in a stowed position;

Figure 3 shows a plan view of the duct system and heat transfer chamber of the airflow control system;

Figures 4A and 4B are sectional views of the rear of the vehicle illustrating the airflow over the vehicle and through the airflow control system with the rear wing stowed and deployed respectively; and

Figures 5A and 5B show simplified versions of the airflow over the rear of the vehicle and through the airflow control system with the rear wing stowed and deployed respectively. DETAILED DESCRIPTION

An active airflow control system 1 in accordance with an embodiment of the present invention will now be described with reference to the accompanying Figures. The airflow control system 1 provides aerodynamic cooling for a motor vehicle 3. The vehicle 3 is a hybrid vehicle having an internal combustion engine (not shown) and an electric drive motor (not shown). In the present embodiment, the internal combustion engine is mid-mounted and is located in an engine bay 5 provided at the back of the vehicle 3.

The airflow control system 1 comprises a rear wing 7, having a leading edge 9 and a trailing edge 1 1 , which is movably mounted on an upper surface 13 of the vehicle 3. The rear wing 7 extends transversely across the rear of the vehicle 3 and has an aerofoil cross section for generating down force. The rear wing 7 is movable between a deployed position (shown in Figures 1 A and 1 B) and a stowed position (shown in Figure 2). In the deployed position, the rear wing 7 projects above the upper surface 13 and extends into the airflow over the rear of the motor vehicle 3. In the stowed position, the rear wing 7 sits substantially flush with the upper surface 13 of the motor vehicle 3 and is a continuation of the adjacent body panels. The airflow control system 1 further comprises an internal duct system 15 formed in the rear of the vehicle 3. As shown in Figure 3, the duct system 15 is bifurcated and comprises first and second ducts 17, 19 which extend in a rearwards direction from respective first and second air inlets 21 , 23. The first and second inlets 21 , 23 are located on the right and left flanks respectively of the vehicle 3 above and to the front of the rear wheels 25. The first and second ducts 17, 19 extend towards the rear of the vehicle along each side of the engine bay 5. It will be appreciated that the location of the first and second inlets 21 , 23 could be changed for other vehicle designs. The vehicle 3 is also provided with an engine inlet 27 provided on each side of the vehicle in front of the rear wheels 25 for supplying air directly to the engine bay 5.

The duct system 15 further comprises a heat transfer chamber 29 positioned at the rear of the engine bay into which the first and second ducts 17, 19 converge. The heat transfer chamber 29 is in fluid communication with the first and second ducts 17, 19 of the duct system 15 to receive air from the first and second inlets 21 , 23. A controlled outlet 31 is formed at the top of the heat transfer chamber 29 to provide a fluid communication pathway to atmosphere in the upper surface 13 of the vehicle 3. The rear wing 7 is positioned over the controlled outlet 31 to selectively alter the flow of air exiting the heat transfer chamber 29 through the controlled outlet 31 , as described herein. As shown in Figure 2, the heat transfer chamber 29 also has three aft apertures 33, 35, 37 provided in a rear surface 39 of the vehicle 3. The aft apertures 33, 35, 37 are open to atmosphere continuously and allow air to vent from the back of the vehicle 3. The heat transfer chamber 29 is separate from the engine bay 5 and fluid communication is limited apart from through the aft apertures 33, 35, 37. A curved transverse body panel 41 is provided above the aft apertures 33, 35, 37. A diffuser 43 is provided on an underside of the vehicle 3 and projects rearwards beyond the rear surface 39.

The rear wing 7 is positioned on the upper surface 13 of the vehicle 3 and, when in said stowed position, the trailing edge 1 1 is coincident with the rear surface 39 of the vehicle 3. When moved to the deployed position, the rear wing 7 travels up and back relative to the vehicle 3 such that the trailing edge 1 1 projects beyond the rear surface 39. The angular orientation of the rear wing 7 can also be varied to adjust the angle of attack a relative to an incident airflow travelling over the upper surface 9 of the vehicle 3. A first actuator (not shown) is provided to control the translation of the rear wing 7 and a second actuator (not shown) is provided to control the angular orientation of the rear wing 7. A heat exchanger 45 (or cooling pack) is provided in the heat transfer chamber 29. The heat exchanger 45 extends in a transverse direction and divides the heat transfer chamber 29 into a front section 47 and a rear section 49. The heat exchanger 45 has a front surface 51 which is exposed to the cooling air in the front section 47 supplied from the first and second ducts 17, 19. A back surface 53 of the heat exchanger 45 faces the rear section 49 of the heat transfer chamber 29 which is continuously open to atmosphere via the aft apertures 33, 35, 37. The heat exchanger 45 has a matrix construction which enables the passage of air from the front section 47 to the rear section 49 to promote cooling. A baffle plate 55 is provided in the heat transfer chamber 29 to guide air from the front section 47 towards the diffuser 43. The baffle plate 55 defines a lower wall of the rear section 49 of the heat transfer chamber 29 and separates the heat transfer chamber 29 from the engine bay 5. An outlet channel 57 is formed from the rear section 49 of the heat transfer chamber 29 to the controlled outlet 31 . The flow of air through the outlet channel 57 is controlled depending on the position and/or orientation of the rear wing 7. The airflow from the first and second ducts 17, 19 into the heat transfer chamber 29 and then through the outlet channel 57 is illustrated by vectors in Figures 4a and 4b which are sectional views along a longitudinal centre line of the vehicle 3. A simplified version of these sectional views is shown in Figures 5a and 5b. As shown in Figures 4a and 5a, when the rear wing 7 is in said stowed position, the controlled outlet 31 is closed and flow through the outlet channel 57 is substantially inhibited. As shown in Figures 4b and 5b, when the rear wing 7 is in said deployed position, the controlled outlet 31 is open and flow through the outlet channel 57 is enabled. The position and/or orientation of the rear wing 7 can actively control the airflow through the outlet channel 57. Specifically, by inclining the rear wing 7 downwardly such that the angle of attack a is negative relative to the incident airflow (as shown in Figures 4b and 5b), airflow accelerates along the underside of the rear wing 7 and a region of low pressure is established adjacent to the upper surface 13 of the vehicle 3 (represented by a concentration of vectors in Figure 4b). The underside of the rear wing 7 can be referred to as the suction side; and the upper side as the pressure side. The low pressure region entrains air from the outlet channel 57 into the airflow over the upper surface 13 of the vehicle 3. The position and/or angular orientation of the rear wing 7 relative to the vehicle 3 can be varied to alter the position and magnitude of the low pressure region. Thus, the rear wing 7 can be configured to control airflow through the heat exchanger 45 to increase or decrease cooling, as required. The aerodynamic down force generated by the rear wing 7 will also depend on its position and/or angular orientation. The shape/profile of the rear wing 7 will also influence the aerodynamic forces generated.

A temperature sensor (not shown) is provided for monitoring the temperature of the heat exchanger 45. A controller (not shown) is provided to deploy the rear wing 7 to increase the air flow through the heat exchanger 45 when the detected temperature reaches a pre-defined threshold. The controller is also configured to deploy the rear wing 7 to generate aerodynamic down force, for example when the vehicle speed reaches a pre-defined threshold. The controller can also over-deploy the rear wing 7 to function as an aero-brake. The controller could also be configured to deploy the rear wing 7 to provide increased cooling of the heat exchanger 45 when a particular drive mode is selected by a user, for example to compensate for expected increases in the operating temperatures.

The rear wing 7 can be deployed to multiple positions depending on the vehicle operating conditions. For example, the rear wing 7 can be deployed to a position to prioritise cooling of the heat exchanger 45 (a so-called "cooling" position); or to prioritise generation of an aerodynamic down force (a so-called "down force" position). The controller could be configured to control the rear wing 7 based on the following pre-defined instructions:

(a) Displace the rear wing 7 to said stowed position or maintain the rear wing in said stored position when the vehicle 3 is cold or the vehicle 3 is off;

(b) Displace the rear wing 7 to said deployed position or maintain the rear wing in said deployed position due to vehicle stability requirements;

(c) Displace the rear wing 7 to said deployed position or maintain the rear wing in said deployed position to satisfy cooling requirements; (d) Displace the rear wing 7 to said deployed position or maintain the rear wing in said deployed position in response to manual override; and

(e) Displace the rear wing 7 to said deployed position or maintain the rear wing in said deployed position to perform thermal soak to dissipate heat after the vehicle has stopped.

When the vehicle 3 is in motion, air enters the first and second ducts 17, 19 through the first and second inlets 21 , 23. The air travels through the first and second ducts 17, 19 and enters the front section 47 of the heat transfer chamber 29. The air flows past the heat exchanger 45 into the rear section 49 of the heat transfer chamber 29 and exits through the central aperture 35 and the left and right apertures 33, 37. Airflow through the heat transfer chamber 29 dissipates some heat from the heat exchanger 45. When the temperature of the heat exchanger 45 reaches the pre-defined temperature threshold, the controller controls the actuators to deploy the rear wing 7. Deployment of the rear wing 7 opens the controlled outlet 31 and establishes an additional flow path through the outlet channel 57. The incident airflow establishes a region of low pressure (reduced or negative static pressure) on the suction side of the rear wing 7 adjacent to the controlled outlet 31 . A pressure differential is created across the outlet channel 57 which promotes the flow of air through the heat transfer chamber 29 before exiting through the controlled outlet 31 . The airflow through the heat transfer chamber 29 and over the heat exchanger 45 is thereby increased when the rear wing 7 is deployed.

The controller can be configured to alter the position and/or orientation of the rear wing 7 actively to control the airflow exiting the heat transfer chamber 29. For example, to increase the airflow through the heat transfer chamber 29, and therefore cooling of the heat exchanger 45, the leading edge 9 of the rear wing 7 can be lowered or the trailing edge 1 1 raised (thereby increasing the negative angle of attack a). The controller can also configure the rear wing 7 to generate aerodynamic down force in response to vehicle operating parameters, such as vehicle speed or lateral loading.

The embodiment described herein relates to a heat exchanger 45 located in the heat transfer chamber 29. The present invention could be used to provide cooling of other vehicle systems, such as a vehicle braking system, an electric drive motor or an internal combustion engine. The rear wing 7 could be operated to control the flow of air over the vehicle system to control the transfer of heat. It will be appreciated that various changes can be made to the present invention without departing from the scope of the present application. For example, a movable valve member which is separate from (and operable independently of) the rear wing 7, could be provided for opening and closing the controlled outlet 31 .