Rear airflow system of a high-performance battery-electric vehicle

Abstract

The invention relates to an air guidance system for a rear area of ​​a battery-electric vehicle (1), comprising an air inlet (3) with a closing element (5) for selectively closing and opening the air inlet (3), and comprising a stowable rear spoiler (7) which is arranged so close above the air inlet (3) that air accumulating in front of the rear spoiler (7) is forced into the air inlet (3) when the air inlet (3) is open, and comprising a control unit which is designed to move the closing element (5) between a position closing the air inlet (3) and a position fully opening the air inlet (3) depending on the vehicle speed, and to keep the rear spoiler (7) in its stowed position and the air inlet (3) in its open position when the battery is being charged while the vehicle (1) is stationary.

Description

[0001] The invention relates to an air guidance system for a rear area of ​​a battery-electric vehicle, a vehicle with such an air guidance system, and a method for cooling an electrical component of a battery-electric vehicle during a charging process.

[0002] In the prior art, various air guiding arrangements for motor vehicles are known in order to adjust air flows such as a cooling air flow as desired.

[0003] In this context, DE 10216969 B4 relates to an air guiding arrangement for a motor vehicle with an air guiding element in the form of a NACA air inlet with a floor element which extends from an outer skin of the motor vehicle into an interior region within a body of the motor vehicle in such a way that an opening is formed in the outer skin, wherein the floor element is designed to be pivotable with respect to the outer skin in such a way that the floor element selectively closes the NACA air inlet in a closed position, wherein the floor element is shaped in such a way that it follows an external shape of the outer skin when the NACA air inlet is closed.

[0004] DE 10 2019 133 502 B4 also relates to an air guiding arrangement for a motor vehicle with at least one air guiding element which extends at least partially in the transverse direction of the motor vehicle in the bow region of the motor vehicle and which can be transferred from a retracted rest position into an extended air guiding position by at least one actuator, wherein the air guiding element is movably connected to a body part of the motor vehicle via a deployment arrangement, wherein the air guiding element has an airfoil profile which generates dynamic lift in the extended state with increasing speed, wherein the deployment arrangement in the extended state extends through an opening in the bow region, wherein the opening is provided in the underbody element of the bow region and is closed by a closure arrangement in the extended state of the deployment arrangement, wherein the air guiding element is firmly connected to the deployment arrangement.

[0005] DE 10 2011 053 500 B4 further relates to a cooling device for a motor vehicle with an internal combustion engine arranged in the rear region of a vehicle body with a charge air cooler arranged below a rear spoiler, wherein the rear spoiler has a position retracted into the vehicle body and a position extended from the vehicle body, wherein the charge air cooler is arranged in a stationary manner in an air duct formed in the rear region of the vehicle body and, when the rear spoiler is extended from the vehicle body, cooler supply air flows into the air duct from a vehicle upper side upstream of the rear spoiler via an inlet opening and cooler exhaust air flows out via a rear outlet opening of an exhaust air nozzle.

[0006] EP 2 655 170 B1 further relates to a motor vehicle having at least one cooling air duct formed in a floor plate thereof for supplying a wheel brake device of the motor vehicle with a cooling air flow, wherein the at least one cooling air duct is assigned an adjustable closure element in the form of a closure plate, which in turn can be transferred, depending on a sensed operating state of the wheel brake device and / or depending on the driving speed of the motor vehicle, into an operating position in which the cooling air duct is at least partially opened and the cooling air flow is permitted, and further can be transferred into an operating position in which the cooling air duct is closed and said cooling air flow is prevented, wherein moreover one or more further operating positions of the closure plate are provided, in which the same, forming a wheel spoiler,protrudes beyond the base plate of the vehicle towards the running surface of the vehicle.

[0007] DE 20 2016 102 751 U1 further relates to an underbody air and heat management system for a motor vehicle, comprising: an aerodynamic fairing comprising a flap system that is selectively displaceable between an open position and a closed position; a spoiler that is selectively displaceable between a basic position and an extended position; and a control system for displacing the flap system between the open position and the closed position and the spoiler between the basic position and the extended position.

[0008] Finally, DE 10 2019 133 502 B4 relates to an air guiding arrangement for a motor vehicle with at least one air guiding element which extends at least partially in the transverse direction of the motor vehicle in the bow region of the motor vehicle and which can be transferred from a retracted rest position into an extended air guiding position by at least one actuator, wherein the air guiding element is movably connected to a body part of the motor vehicle via a deployment arrangement, wherein the air guiding element has an airfoil profile which generates dynamic lift in the extended state with increasing speed, wherein the deployment arrangement in the extended state extends through an opening in the bow region, wherein the opening is provided in the underbody element of the bow region and is closed by a closure arrangement in the extended state of the deployment arrangement, wherein the air guiding element is firmly connected to the deployment arrangement.

[0009] DE 10 2011 00006A21 provides air inlets in the engine compartment grille of a rear-mounted motor vehicle through which cooling air can be supplied to the engine compartment. Additional cooling air is supplied through openings on the front side of the rear lid. When the rear spoiler is extended, a gap is created between the rear edge of the rear lid and the front edge of the rear spoiler through which air flows downwards. When the rear spoiler is retracted, an engine scavenging fan is provided to ventilate the engine compartment with cooling air. This fan draws cooling air through air inlets in the engine compartment grille.

[0010] US 2019 038 2061 A1 discloses a flow guidance arrangement for a motor vehicle. This arrangement comprises a vane arrangement arranged in a rear region of the motor vehicle, comprising a vane element and an underflow channel with a channel inlet and a channel outlet. The channel inlet is arranged upstream of the vane element, and the channel outlet is arranged below the vane arrangement. A throttle device is fluidically associated with the underflow channel, which is designed to be motor-actuated and via which an effective flow cross-section of the underflow channel can be varied.

[0011] In a high-performance, battery-electric vehicle for road traffic, the cooling requirements differ dramatically between driving at a constant, relatively slow speed and charging; even longer, fast forward journeys lead to considerable waste heat generation. Such a vehicle requires a very high cooling airflow at constant speeds around 300 km / h, which is quite different from the requirements during charging, while slow forward journeys require little or no additional cooling via an airflow supplied from the ambient air. To achieve the required aerodynamic and thermodynamic efficiency and to enable maximum range, air resistance must be reduced, and lift coefficients, including those on the rear axle, must be dynamically adjusted, while thermal management for the battery and an EDU must be implemented.In some cases, the air intakes at the front of the vehicle cannot be designed to achieve the mass flow of air required for loading or maximum speed. Therefore, additional openings are typically required.

[0012] The object of the invention is to improve thermodynamic and aerodynamic properties at the inlet of a cooling air flow in the rear area of ​​a battery-electric high-performance vehicle.

[0013] The invention is based on the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims.

[0014] A first aspect of the invention relates to an air guidance system for a rear area of ​​a battery-electric vehicle, comprising an air duct for guiding ambient air for cooling an electrical component of the vehicle, and an air inlet on the air duct, wherein the air inlet has a closing element which is vertically adjustable by control in the rear area of ​​the air inlet along the inlet flow in order to selectively close and open the air inlet, as well as comprising a rear spoiler which is selectively extendable and stowable by control and which is arranged so close above the air inlet that a local overpressure building up in front of the rear spoiler due to aerodynamic back pressure forces air accumulating in front of the rear spoiler into the air inlet when the air inlet is open, and comprising a control unit which is designed toDepending on the vehicle speed, to move the closing element between a position that closes the air intake and a position that fully opens the air intake, and to keep the rear spoiler in its stowed position and the air intake in its open position when charging the battery while the vehicle is stationary.

[0015] The air intake is preferably designed as a NACA air intake. Also known as a NACA inlet and NACA opening, this is a special type of aerodynamic intake designed to enable efficient airflow into an aircraft or vehicle. The NACA inlet was developed by the National Advisory Committee for Aeronautics (NACA), the forerunner of NASA, and is widely used in aerospace and automotive applications.

[0016] NACA intakes were designed to provide a sleek and efficient way to introduce air into an aircraft's cooling system, engine compartment, or other areas requiring airflow. They feature a curved shape and smooth contours that reduce drag and improve aerodynamic performance.

[0017] The design of a NACA intake is based on specific aerodynamic principles to ensure optimal airflow characteristics. Through targeted inlet design, the airflow, velocity, and pressure distribution can be influenced to meet the requirements of the system being cooled or ventilated.

[0018] The air guidance system is designed for an area on the upper side of the rear of a battery-electric high-performance vehicle. Such a high-performance vehicle is expected to reach significantly higher speeds than conventional battery-electric vehicles. Since very high speeds are associated with very high air resistance, correspondingly high power levels are required from the drive of the battery-electric vehicle for longer periods. The battery itself and the power electronics may require considerable cooling capacity, which can be achieved at least in part by means of ambient airflow. However, considerable cooling capacity is also required when charging a vehicle's battery in order to cool down components that heat up, such as the vehicle's battery, during charging. This serves to ensure safety and increases the service life of the battery.

[0019] On the other hand, at such high speeds, any change in the aerodynamic configuration can have significant effects, which can influence both the cooling performance and the aerodynamic drag of the vehicle and thus its efficiency.

[0020] Therefore, according to the invention, a control unit checks the current state of the vehicle; if it is stationary and a vehicle battery is being charged, the air inlet for the air duct is opened. While opening the air inlet into the air duct can have a negative impact on the efficiency of the vehicle when driving forward, this is irrelevant when the vehicle is stationary and it can be ensured that a sufficiently large mass flow can be guided into the air duct, for example by means of a fan. Preferably, the rear spoiler is also moved to its stowed position in order to impede the ambient air flowing into the air inlet to the air duct as little as possible.

[0021] In addition, at very high speeds, the control unit moves the closing element to an open position, opening the air inlet for the air duct. At such high speeds, particularly high cooling performance is required; the incoming air can thus be at least partially introduced into the air inlet of the air duct through the opening of the closing element. However, at such high speeds, high roadholding is typically also required, which is generated by an aerodynamic downforce using the rear spoiler. For this purpose, the rear spoiler is preferably moved to its extended position at these high speeds.The rear spoiler can be moved between a fully stowed position to minimize aerodynamic drag to a fully extended position without any steps in between; in an alternative embodiment, it can be moved to individual positions between these extremes.

[0022] At slower speeds, however, less cooling power is required, and the closure element can be used to close the air intake for the air duct, increasing the vehicle's aerodynamic efficiency by minimizing drag. The rear spoiler can also be moved to its stowed position in this vehicle condition, preferably to its fully stowed position, to minimize the vehicle's aerodynamic drag.

[0023] The movement of the closing element in response to a signal from the control unit can be effected, for example, electrically, magnetically, hydraulically, pneumatically, or similarly. The closing element is also preferably designed as a plate-shaped element that can be deformed by bending.

[0024] The degree of curvature of the surface of the closing element, which is preferably produced by bending around a front bearing point of the closing element (with respect to the flow direction of the incoming air), determines between an opening and a closing of the air inlet of the air duct.

[0025] If the air intake is designed as a NACA air intake, the closing element moves upwards from a floor level of the NACA air intake away from the body of the vehicle, thus closing the air intake. In a position that opens the air intake, the closing element preferably rests against this floor level and releases the air intake.

[0026] For this purpose, the closing element is preferably made of an elastically deformable structure and is particularly preferably moved by means of an electrical actuator unit.

[0027] Furthermore, by positioning the rear spoiler within certain limits above and behind the air intake, any air accumulating in front of the rear spoiler flows at least partially into the air intake when the air intake is at least partially open. This advantageously increases the mass flow through the air intake into the air duct, and the aerodynamic drag of the rear spoiler is utilized to its full potential.

[0028] As explained above, the control unit continuously monitors the vehicle's status. While the vehicle is stationary and charging, the closing element is opened to allow air intake for cooling during charging, while the vehicle is moving forward, active control of the closing element is possible. A speed-dependent limit is specified, which can take into account other parameters, such as the current battery temperature or the temperature of the power electronics.

[0029] The limit can therefore be directly and by default speed-dependent, or it can be indirectly and implicitly speed-dependent, for example, through temperature measurements on the battery or power electronics. On particularly cold days, the limit can therefore be higher than on hot summer days.

[0030] However, in any case, the limit is expected to be speed-dependent. It is advantageous to keep the closure element in the closed position and the rear spoiler in the stowed position for as long as possible to maximize the vehicle's aerodynamic efficiency.

[0031] Advantageous effects of the invention include the fact that, through adaptive control of the control unit depending on the vehicle condition and the required (actual or expected) cooling capacity, the aerodynamic configuration of the vehicle's rear can be adjusted to simultaneously minimize aerodynamic drag and take into account aerodynamic lift and downforce requirements. Driving stability can also be considered by selecting the switching times between the opening and closing of the air intake by the closing element and a change in the position of the rear spoiler accordingly.

[0032] According to an advantageous embodiment, the control unit is designed to keep the rear spoiler in its stowed position and to keep the air inlet in a closed position when the vehicle is traveling at a forward speed other than zero and simultaneously falls below a predetermined speed-dependent limit value.

[0033] According to a further advantageous embodiment, the control unit is designed to keep the rear spoiler in an at least partially extended position and the air inlet in an at least partially open position when the vehicle is traveling at a forward speed above the predetermined speed-dependent limit. Preferably, the rear spoiler is held in a fully extended position and the air inlet is held in a fully open position.

[0034] According to the embodiment of the invention, the closing element is flexible and plate-shaped, wherein the closing and opening of the air inlet is each achieved by bending the closing element.

[0035] According to a further advantageous embodiment, the closing element, in the state closing the air inlet, adjoins the cover element in a common plane with a cover element below the rear spoiler.

[0036] According to a further advantageous embodiment, a heat exchanger is arranged in the air duct. The heat exchanger is heated by the heat of an electrical component of the vehicle and cooled by the air mass flow flowing through the air duct. Thus, the electrical components of the vehicle are cooled by means of the heat exchanger.

[0037] According to a further advantageous embodiment, the air duct has an air outlet to the environment downstream of the heat exchanger in the direction of flow. This air outlet advantageously allows the air heated by the heat exchanger to be discharged, along with the absorbed heat.

[0038] According to a further advantageous embodiment, a propeller is arranged in the air duct.

[0039] The propeller can be designed as a propeller, but can also be referred to as a shrouded propeller due to its geometric boundary conditions. The propeller is used in particular to draw in ambient air when the vehicle is stationary and charging its battery and to pass it through a heat exchanger. Heat from the battery or power electronics can be collected in this heat exchanger, and thermal energy can be dissipated by the mass flow flowing through the air duct. The propeller is therefore particularly crucial when the vehicle is stationary while charging its battery, as this naturally lacks the aerodynamic dynamic pressure that also occurs at the rear of the vehicle when the vehicle is moving forward. This pressure can be used for natural inflow, for example into the air intake.

[0040] A further aspect of the invention relates to a vehicle with an air guidance system as described above and below, wherein at least one air inlet and at least one rear spoiler are each arranged on an upper side of the vehicle, wherein the air inlet leads with a horizontal component from the front of the vehicle towards the rear of the vehicle and with a vertical component from top to bottom, in each case in the inflow direction of the air.

[0041] According to a further advantageous embodiment, two air inlets are arranged in a rear area of ​​the vehicle.

[0042] Advantages and preferred further developments of the proposed vehicle result from an analogous and analogous transfer of the statements made above in connection with the proposed air guidance system.

[0043] A further aspect of the invention relates to a method for cooling an electrical component of a battery-electric vehicle during a charging process, wherein an air guidance system is used at a rear region of the battery-electric vehicle, and by controlling a control unit, an air duct for guiding ambient air for cooling the electrical component is released through an air inlet by a closing element that is vertically adjustable in its rear region along the inlet flow is brought into a position that opens the air inlet and an adjustable rear spoiler is stowed away and an air screw is activated in the air duct for sucking in ambient air through the air inlet.

[0044] Advantages and preferred developments of the proposed method result from an analogous and analogous transfer of the statements made above in connection with the proposed air guidance system.

[0045] Further advantages, features, and details will become apparent from the following description, which—if appropriate, with reference to the drawings—describes at least one embodiment in detail. Identical, similar, and / or functionally equivalent parts are provided with the same reference numerals.

[0046] They show: Fig. 1: A vehicle with a rear air guidance system according to an embodiment of the invention. Fig. 2: An air guidance system according to an embodiment of the invention. Fig. 3: The air guidance system of the Fig. 2 in a first state. Fig. 4: The air guidance system of the Fig. 2 in a second state. Fig. 5: The air guidance system of the Fig. 2 in another state.

[0047] The representations in the figures are schematic and not to scale.

[0048] Fig. Figure 1 shows a vehicle 1 having a battery large enough to power an electric drive of the vehicle 1 for sufficiently long periods of time. The vehicle 1 is a high-performance vehicle and reaches speeds of 300 km / h and more. At such high speeds, a considerable amount of stationary cooling is required for electric drive components such as the battery. Therefore, an active air guidance system is arranged within the dashed circle marking the rear of the vehicle 1, which, in different states, can be Fig. 2 to Fig. 5 is described in more detail. The Fig. 2 to Fig. 5 therefore each show in a cross-section different adjustable states, which are explained below.

[0049] Fig. 2 shows a cross-section of an air guidance system, in the same perspective as the vehicle 1 in Fig. 1, for the rear of the battery electric vehicle 1 of the Fig. 1. When the vehicle 1 is moving forward, it is therefore to be expected that the air flow arrives from the roof of the vehicle 1 in the image plane from left to right. The air guidance system has an air duct for guiding ambient air for cooling an electrical component of the vehicle 1 by means of a heat exchanger 9. A closing element 5 is provided at the air inlet 3 of the air duct, which closing element 5 can be vertically adjusted by actuation in the rear region of the air inlet 3 along the inlet flow in order to selectively close and open the air inlet 3. For this purpose, the closing element 5 is fixedly mounted at its front end in the direction of flow and can be deformed into different bending shapes by means of an actuator. In the state of Fig. 2, it rests against a base plate of the air inlet 3, which is designed as a NACA air inlet, and thus releases the air inlet 3. Furthermore, a rear spoiler 7 is provided, which can be moved vertically from a stowed to an extended position by another actuator. In the state of Fig. 2, the rear spoiler 7 is in its stowed position. These positions were set by the control unit by controlling the two actuators so that in the example of the Fig. 2 The vehicle 1 is stationary and charging the battery. The dashed arrows depict current paths. Air flows into the air intake 3 from the roof and rear window of the vehicle 1 due to the vehicle 1 being stationary, and air can also flow in via the stowed rear spoiler 7. The air is drawn in by the rotating fan 11 and used by the heat exchanger 9 to cool the electrical components of the vehicle 1.

[0050] Fig. 3 shows the air guidance system of the Fig. 2 in a state of the vehicle 1, which is in forward travel. Here, the control unit detects that cooling power is still required, therefore the opening of the air intake 3 is released by the closing element 5, air flows over the roof of the vehicle 1 and along the rear window into the air intake 3, for example because on a hot summer day the electrical components still have an elevated temperature after the charging process. The rear spoiler 7, however, is still held in its retracted position by the control unit, since the control unit detects that no greater driving performance of the vehicle 1 is required, particularly in curves, and thus special downforce is not needed. This can be the case, for example, if the vehicle 1 is not operated in a sport mode or extremely high speeds and / or cornering acceleration are not present.

[0051] Fig. 4 shows the air guidance system of the Fig. 2 in a further state, namely for slow forward speed of the vehicle 1, at which the aerodynamic resistance is reduced as much as possible, no increased cooling capacity is required and no particularly high cornering performance of the vehicle 1. Therefore, the control unit controls the closing element 5 to close the air inlet 3, the incoming air along the rear window of the vehicle 1 flows out via the retracted rear spoiler 7 without major disruptions.

[0052] Fig. 5 shows the air guidance system of the Fig.2 in a further state, namely for very high forward speeds of the vehicle 1, where high cooling performance is required and agile driving dynamics are also desired. For this purpose, the control unit controls the closing element 5 to open the air inlet 3 and the rear spoiler 7 to extend into its extended position. Due to the high flow velocity at the rear spoiler 7, a dynamic pressure area forms at its front end, which leads to the additional deflection of an air flow into the air inlet 3 and thus further increases the cooling performance at the heat exchanger 9.

[0053] Although the invention has been illustrated and explained in detail by preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of variations exist. It is also clear that the embodiments mentioned by way of example are truly only examples and should not be construed as limiting the scope, possible applications, or configuration of the invention in any way.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without departing from the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description. List of reference symbols 1 vehicle 3 Air intake 5 locking element 7 rear spoiler 9 heat exchangers 11 Propeller

Claims

[1] Air guidance system for a rear area of ​​a battery-electric vehicle (1), comprising an air duct for guiding ambient air for cooling an electrical component of the vehicle (1), and an air inlet (3) on the air duct, wherein the air inlet (3) has a closing element (5) which is vertically adjustable by control in the rear area of ​​the air inlet (3) along the inlet flow in order to selectively close and open the air inlet (3), and comprising a rear spoiler (7) which is selectively extendable and stowable by control and is arranged so close above the air inlet (3) that a local overpressure building up in front of the rear spoiler (7) due to aerodynamic back pressure forces air accumulating in front of the rear spoiler (7) into the air inlet (3) when the air inlet (3) is open, and comprising a control unit which is designed todepending on a vehicle speed, to move the closing element (5) between a position closing the air inlet (3) and a position completely opening the air inlet (3), and to keep the rear spoiler (7) in its stowed position and the air inlet (3) in its open position when charging the battery while the vehicle (1) is stationary, , characterized by that the closing element (5) is flexible and plate-shaped, wherein the closing and opening of the air inlet (3) is each brought about by bending deformation of the closing element (5). [2] Air guidance system according to claim 1, wherein the control unit is designed to keep the rear spoiler (7) in its stowed position and to keep the air inlet (3) in a closed position when the vehicle (1) is traveling at a forward speed other than zero and at the same time falling below a predetermined speed-dependent limit value. [3] Air guidance system according to one of the preceding claims, wherein the control unit is designed to hold the rear spoiler (7) in an at least partially extended position and to hold the air inlet (3) in an at least partially open position when the vehicle (1) is traveling at a forward speed above the predetermined speed-dependent limit value. [4] Air guidance system according to claim 3, wherein the closing element (5) in the state closing the air inlet (3) adjoins the cover element in a common plane with a cover element below the rear spoiler (7). [5] Air guidance system according to one of the preceding claims, wherein a heat exchanger (9) is arranged in the air duct. [6] Air guidance system according to one of the preceding claims, wherein a propeller (11) is arranged in the air duct. [7] Vehicle (1) with an air guidance system according to one of the preceding claims, wherein at least one air inlet (3) and at least one rear spoiler (7) are each arranged on an upper side of the vehicle (1), wherein the air inlet (3) leads with a horizontal component from the front of the vehicle towards the rear of the vehicle and with a vertical component from top to bottom, in each case in the inflow direction of the air. [8] Vehicle (1) according to claim 7, wherein two air inlets (3) are arranged in a rear region of the vehicle (1). [9] Method for cooling an electrical component of a battery-electric vehicle (1) during a charging process, wherein an air guidance system is used at a rear region of the battery-electric vehicle (1), and by controlling a control unit, an air duct for guiding ambient air for cooling the electrical component is released through an air inlet (3) by bringing a closing element (5) which is vertically adjustable in its rear region along the inlet flow into a position opening the air inlet (3), and stowing an adjustable rear spoiler (7) and activating a propeller (11) in the air duct for sucking in ambient air through the air inlet (3).

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