The present invention relates generally to vehicles and, more particularly, to an automotive radiator and condenser airflow system.
Vehicle cooling systems vary widely in complexity, depending primarily upon the thermal requirements of the various vehicle systems employed in the vehicle in question. In general, these cooling systems utilize heat exchangers of one form or another to transfer the heat generated by the vehicle subsystems to the surrounding ambient environment. Such heat transfer may either be performed directly, for example in the case of a simple radiator coupled to a vehicle engine, or indirectly, for example in the case of a thermal management system utilizing multiple heat transfer circuits to transfer the heat through multiple stages in order to sufficiently lower the temperature of the component in question.
In general, vehicle heat exchangers are designed to exchange heat between two different fluids, or two similar fluids that are at different temperatures, thereby helping to maintain the various vehicle systems and components within a safe and effective operating range of temperatures. One of the fluids is typically composed of a refrigerant or water, the water often mixed with ethylene glycol or propylene glycol or a similar liquid that provides anti-freeze protection at low temperatures. In many vehicle heat exchangers such as condensers and radiators, the second fluid is air which is forced to flow through the heat exchanger, either as a result of vehicle movement or through the use of a fan.
Within the automotive industry there are several types of air heat exchangers, the design of each being based on their intended application. Exemplary heat exchangers include:
A powertrain radiator in which a coolant-to-air heat exchanger is used to remove heat from an internal combustion engine or electric motor.
A condenser in which a refrigerant-to-air heat exchanger is used to remove heat for cabin air conditioning systems or other systems (e.g., battery packs and power electronics) that employ refrigerant as the cooling fluid.
A transmission oil cooler in which an oil-to-air heat exchanger is used to remove heat from the transmission via the transmission fluid.
A steering pump oil cooler in which an oil-to-air heat exchanger is used to remove heat from the steering system via the steering fluid.
A charge air cooler in which an air-to-air heat exchanger is used to remove heat from turbocharged (compressed) air used in the engine intake system.
For a given set of fluid temperatures, the performance of a fluid-to-fluid heat exchanger depends primarily on the surface area of the heat exchanger and the volume flow rate of the two fluids through the heat exchanger. Flow rate is commonly determined as the fluid velocity through the heat exchanger multiplied by the frontal area of the heat exchanger. Larger heat exchanger surface areas and mass flow rates result in greater heat transfer from the inner fluid to the outer fluid. An increase in these same variables, however, also results in an increase in the hydraulic losses, or pressure drop losses, which are manifested in increased aerodynamic drag (i.e., vehicle motive power), pump power, and fan power. Additionally, in a fluid-to-fluid heat exchanger, the transfer of heat between the two fluids increases as the temperature difference between the two fluids increases.
In a conventional vehicle utilizing multiple heat exchangers, regardless of whether the vehicle utilizes a combustion engine, an electric motor, or a combination of both (i.e., a hybrid), the individual heat exchangers are typically positioned one in front of the other, followed by a fan, this configuration referred to as a “stack”. In such a stacking arrangement, commonly the heat exchanger with the lowest outlet air temperature is located upstream, followed by higher temperature heat exchangers downstream. An example of such a configuration is a condenser followed directly by an engine radiator, followed by one or more fans. While this arrangement is more common with vehicles utilizing a combustion engine, hybrid vehicles may also use a stack of heat exchangers in order to provide cooling for the battery pack, power electronics and the motor. A principal drawback of the practice of stacking heat exchangers is an increase in hydraulic losses (i.e., fan power, aerodynamic drag) that result regardless of whether each heat exchanger in the stack is in active use. Additionally, since the temperature of the air entering the inner heat exchanger(s) will be the temperature of the air exiting the upstream heat exchanger which is typically higher than the ambient temperature, the efficiency and overall performance of the inner heat exchanger(s) is compromised. As a consequence, it is common practice to increase the surface area or thickness of the downstream heat exchangers to compensate for this decrease in expected performance which, in turn, adds weight and cost to the affected heat exchangers.
While a variety of different techniques and system configurations have been used to control the temperatures of the various subsystems and components in a vehicle, they are often inefficient, which in turn affects vehicle performance. Accordingly, what is needed is a thermal management system that maximizes heat transfer while minimizing the hydraulic power consumed in the process. The present invention provides such a thermal management system.
A vehicle thermal management system is provided that is comprised of at least first and second heat exchangers configured in a non-stacked arrangement, wherein the first heat exchanger is coupled to a first vehicle cooling subsystem and the second heat exchanger is coupled to a second vehicle cooling subsystem; a first air inlet, wherein air flowing through the first air inlet flows directly into the first heat exchanger without first passing through the second heat exchanger; a second air inlet, wherein air flowing through the second air inlet flows directly into the second heat exchanger without first passing through the first heat exchanger; and a first set of adjustable louvers that controls air flowing directly through the first air inlet into the first heat exchanger. The system may further comprise a second set of adjustable louvers that controls air flowing directly through the second air inlet into the second heat exchanger. The second set of adjustable louvers may be located between the second heat exchanger's airflow entrance surface and the ambient environment. The first and second sets of adjustable louvers may each have a first, fully opened position and a second, fully closed position. The first and second sets of adjustable louvers may each be adjustable over a range of positions between fully opened and fully closed. The first and second sets of adjustable louvers may each be comprised of two or more groups of adjustable louvers that are independently operable from one another.
In one aspect of the invention, an air duct couples at least a portion of the airflow exit surface of the first heat exchanger to an airflow entrance surface of the second heat exchanger. If there is a single set of adjustable louvers, they may be (i) positioned within the air duct and between the airflow exit surface of the first heat exchanger and the airflow entrance surface of the second heat exchanger, or (ii) positioned between the second heat exchanger's airflow entrance surface and the ambient environment. If the system includes a second set of adjustable louvers, preferably the first set of adjustable louvers is positioned within the air duct and between the airflow exit surface of the first heat exchanger and the airflow entrance surface of the second heat exchanger and the second set of adjustable louvers is located between the second heat exchanger's airflow entrance surface and the ambient environment, for example adjacent to the second heat exchanger's airflow entrance surface. A fan may be positioned adjacent to the airflow exit surface of the second heat exchanger.
In another aspect of the invention, the system further comprises a second set of adjustable louvers that controls air flowing directly through the second air inlet into the second heat exchanger; a third heat exchanger configured in a non-stacked arrangement with the first and second heat exchangers, wherein the third heat exchanger is coupled to a third vehicle cooling subsystem; a third air inlet, wherein air flowing through the third air inlet flows directly into the third heat exchanger without first passing through either the first or second heat exchangers; and a third set of adjustable louvers that controls air flowing directly through the third air inlet into the third heat exchanger that does not first pass through either the first or second heat exchangers. The first, second and third sets of adjustable louvers may each have a first, fully opened position and a second, fully closed position. The first, second and third sets of adjustable louvers may each be adjustable over a range of positions between fully opened and fully closed. The first, second and third sets of adjustable louvers may each be comprised of two or more groups of adjustable louvers that are independently operable from one another. The first, second and third vehicle cooling subsystems may be selected from battery cooling subsystems, refrigeration subsystems, passenger cabin HVAC subsystems, power electronics cooling subsystems, motor cooling subsystems, transmission cooling subsystems, and charging system cooling subsystems. The second and third vehicle cooling subsystems may be the same cooling subsystem. The system may further comprise a first air duct that couples at least a first portion of the airflow exit surface of the first heat exchanger to an airflow entrance surface of the second heat exchanger, and a second air duct that couples at least a second portion of the airflow exit surface of the first heat exchanger to an airflow entrance surface of the third heat exchanger. The first set of adjustable louvers may be comprised of at least a first group and a second group of adjustable louvers, where the first group of adjustable louvers is positioned within the first air duct and between the airflow exit surface of the first heat exchanger and the airflow entrance surface of the second heat exchanger, and where the second group of adjustable louvers is positioned within the second air duct and between the airflow exit surface of the first heat exchanger and the airflow entrance surface of the third heat exchanger. The second set of adjustable louvers may be located between the airflow entrance surface of the second heat exchanger and the ambient environment, for example adjacent to the airflow entrance surface of the second heat exchanger, and the third set of adjustable louvers may be located between the airflow entrance surface of the third heat exchanger and the ambient environment, for example adjacent to the airflow entrance surface of the third heat exchanger. The system may further comprise a first fan adjacent to the airflow exit surface of the second heat exchanger and a second fan adjacent to the airflow exit surface of the third heat exchanger.
In another aspect of the invention, the system further comprises a third heat exchanger configured in a non-stacked arrangement with the first and second heat exchangers, wherein the third heat exchanger is coupled to a third vehicle cooling subsystem; a third air inlet, wherein air flowing through the third air inlet flows directly into the third heat exchanger without first passing through either the first or second heat exchangers; a first air duct that couples at least a first portion of the airflow exit surface of the first heat exchanger to an airflow entrance surface of the second heat exchanger; a second air duct that couples at least a second portion of the airflow exit surface of the first heat exchanger to an airflow entrance surface of the third heat exchanger; a second set of adjustable louvers that controls air flowing directly through the third air inlet into the third heat exchanger that does not first pass through either the first or second heat exchangers, and wherein the first set of adjustable louvers controls air flowing directly through the second air inlet into the second heat exchanger that does not first pass through either the first or third heat exchangers.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
In the following text, the terms “battery”, “cell”, and “battery cell” may be used interchangeably and may refer to any of a variety of different cell types, chemistries and configurations including, but not limited to, lithium ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel zinc, silver zinc, or other battery type/configuration. The term “battery pack” as used herein refers to multiple individual batteries contained within a single piece or multi-piece housing, the individual batteries electrically interconnected to achieve the desired voltage and capacity for a particular application. The term “electric vehicle” as used herein refers to either an all-electric vehicle, also referred to as an EV, plug-in hybrid vehicles, also referred to as a PHEV, or a hybrid vehicle (HEV), a hybrid vehicle utilizing multiple propulsion sources one of which is an electric drive system. It should be understood that identical element symbols used on multiple figures refer to the same component, or components of equal functionality. Additionally, the accompanying figures are only meant to illustrate, not limit, the scope of the invention and should not be considered to be to scale.
Thermal management system 100, as with other embodiments of the invention, includes a number of air ducts that control the flow of air through, or around, the heat exchangers. In the illustrated system, rear ducting 111A prevents air from flowing unimpeded through heat exchanger 101. Rather, the air that flows through the left side of heat exchanger 101 and exits rear heat exchanger surface 112 is forced to flow through heat exchanger 102, following path 113. Similarly, rear ducting 111B forces air flowing through the right side of heat exchanger 101 and exiting rear heat exchanger surface 112 to pass through heat exchanger 103, following path 115. Note that in this and other preferred embodiments, ducting section 117 prevents air from flowing through the left side of heat exchanger 101 without also passing through heat exchanger 102. Similarly, ducting section 119 prevents air from flowing through the right side of heat exchanger 101 without also passing through heat exchanger 103. Alternate embodiments eliminate ducting sections 117/119, thus allowing air to flow through central heat exchanger 101 and then exit the system without also passing through one of the side-mounted heat exchangers 102/103. Note that adjustable louvers may be positioned at ducting sections 117/119, thus allowing control over whether the air flowing through the central heat exchanger 101 passes through a side-mounted heat exchanger.
The forward portions of the air ducting include a pair of air inlets 121 and 123, shown in phantom, which are positioned in front of heat exchangers 102 and 103, respectively. Additionally, the entrance 124 to the central heat exchanger 101 forms a third air inlet that provides a pathway for air to flow directly into heat exchanger 101. Air duct inlet 121 provides an airflow path 125 that bypasses heat exchanger 101 as shown. Similarly, air duct inlet 123 allows air to flow directly through heat exchanger 103 without passing through central heat exchanger 101, following path 127.
Thermal management system 200, shown in
While the use of multiple louvers 301-304 and 401-402 maximizes airflow control through heat exchangers 101-103, it should be understood that the invention may utilize a different number of control louvers, depending primarily upon the constraints and requirements placed on the thermal management system by the vehicle's design. For example, system 500 shown in
As previously noted, in the preferred embodiment of the invention the louvers are completely independent from one another. This allows fine tuning of the thermal management system depending upon the requirements of the vehicle subsystems to which the various heat exchangers are coupled. The arrangement shown in
In at least one preferred embodiment of the invention, the louvers may be positioned in a range of positions from fully open to fully closed, thus allowing fine modulation of the airflow. As a result of allowing a range of louver positions, the thermal management system may be fine-tuned to insure efficient use of the heat exchangers, i.e., achieving the airflow required for cooling while minimizing hydraulic and aerodynamic losses. This aspect of the invention is illustrated in
In an alternate embodiment, fine adjustment of the air flowing through the louvers is achieved by utilizing two or more sets of louvers for each opening where fine control is desired. Preferably each set of louvers is only capable of two positions: fully open or fully closed, thus simplifying louver operation. In an exemplary configuration shown in
At the heart of system 1700 is a thermal management control system 1701. System 1701 may be integrated within another vehicle control system or configured as a stand-alone control system. Typically control system 1701 includes a control processor as well as memory for storing a preset set of control instructions. Coupled to controller 1701 are a plurality of temperature sensors 1703 that monitor the temperature of the various vehicle components in general, and the vehicle components that are coupled to the vehicle cooling systems in particular. Exemplary components that may be monitored include the battery or batteries, motor, drive electronics, transmission, and coolant. Ambient temperature is preferably monitored as well. Depending upon the configuration of the vehicle, the charging system temperature may also be monitored. The monitored temperatures at these various locations are used by control system 1701 to determine the operation of the various thermal management subsystems. In addition to preferably regulating the flow of coolant within the coolant loop(s) utilizing any of a variety of regulators 1705 (e.g., circulation pump operation or flow rate, flow valves, etc.), controller 1701 preferably controls fan operation (e.g., fans 305/306, 1405/1406, etc.). Controller 1701 also controls operation of the louvers (e.g., louvers 301-304, 401-402, 1301A-C, 1302A-C, 1303A-C, 1304A-C, 1407-1410, etc.). Preferably louver control is provided by electro-mechanical actuators although other means may be used (e.g., hydraulic actuators). Preferably control system 1701 is designed to operate automatically based on programming implemented by the system's processor. Alternately, system 1700 may be manually controlled, or controlled via a combination of manual and automated control.
As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention.
This application claims benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/429,825, filed 5 Jan. 2011, the disclosure of which is incorporated herein by reference for any and all purposes.
Number | Date | Country | |
---|---|---|---|
61429825 | Jan 2011 | US |