Patent Publication Number: US-2013239913-A1

Title: Thermal Management System, Vehicle, and Associated Method

Description:
BACKGROUND 
     1. Technical Field 
     Example embodiments relate to a temperature control system. Example embodiments relate to a vehicle thermal management system. Example embodiments relate to a method of thermal management. 
     2. Discussion of Art 
     Some vehicles use a radiator fan located in the from of the engine as a heat exchange mechanism. Such vehicles may include tractor trailers, haulage trucks, passenger cars and trucks, and other mobile assets. The fan for these vehicle types can be driven by the engine through a belt or a mechanical coupling. This arrangement may constrain the system to a single large fan drawing air through a single, square radiator located behind a grill at the front end of the vehicle. Further, speed control of the fan may be affected by engine speed, optionally with a gearing arrangement and/or a clutch. To run the fan and cool the engine under this arrangement, the engine must be in operation, which consumes fuel and creates engine exhaust as a result. Further, the engine coupling to the fan can be a significant drag on the horsepower available to drive the vehicle during operation of the fan. 
     It may be desirable to have a system and vehicle with characteristics that differ from those properties of currently available systems and vehicles. It may be desirable to have a method that differs from those methods currently available. 
     BRIEF DESCRIPTION 
     In one embodiment, a system is provided that includes an engine coupled to an alternator, and a radiator fan motor in electrical communication with the alternator. The radiator fan motor is mechanically decoupled from the engine. The radiator fan motor drives a radiator fan to create an air flow across a radiator of the engine. “Mechanically decoupled” means there is no direct belt or other mechanical linkage from the engine to the radiator fan. 
     In another embodiment, a system is provided that includes an engine coupled to an alternator, and a radiator fan motor in electrical communication with the alternator. The radiator fan motor is mechanically decoupled from the engine. The system further includes an energy storage device in electrical communication with the alternator and the radiator fan motor, and one or more traction motors in electrical communication with the energy storage device, the radiator fan motor, or both. In one mode of operation, electricity provided through dynamic braking is used to power the radiator fan motor upon generation of the electricity. In another mode of operation, the electricity provided through dynamic braking is stored in the energy storage device for use later in powering the radiator fan motor. 
     In another embodiment, a system is provided that includes an engine coupled to an alternator and a plurality of radiator fan motors in electrical communication with the alternator. Each of the radiator fan motors is mechanically decoupled from the engine, and each radiator fan motor drives a respective fan to create an air flow across a radiator. The fans are oriented relative to the radiator to provide an airflow pattern that differs from an airflow pattern that would be created if there was only a single radiator fan associated with the radiator. 
     In another embodiment, a system is provided that includes an engine coupled to an alternator, a plurality of radiators, and a plurality of radiator fan motors in electrical communication with the alternator. The radiator fan motors are mechanically decoupled from the engine. The radiator fan motors are respectively associated with the plural radiators, for creating air flow across the radiators. 
    
    
     
       DESCRIPTION OF FIGURES 
       In the figures and specification, like parts are given corresponding numbers. 
         FIGS. 1-8  are top view schematic representations of various embodiments of a thermal management system. 
         FIG. 9  is a front elevation schematic representation comparing an airflow pattern of a single-fan radiator to an airflow pattern of a multi-fan radiator, according to an embodiment. 
         FIG. 10  is a table of control signals, according to an embodiment. 
         FIG. 11  is a graph showing fan control based on temperature thresholds, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments relate to a thermal management system, such as might be used in a vehicle. Example embodiments also relate to a method of thermal management 
     As defined herein, the term “energy storage device” has a distinct scope from a common “battery,” as defined herein. Where the term “battery” is listed, a common battery such as a lead acid battery is referred to, which is sized and configured to turn over an engine starter and possibly provide for a limited amount of auxiliary load energy for a short period of time. An example of a battery as defined herein is a standard car battery. As defined herein, a battery is insufficient to move a traction motor, run a radiator fan for an extended period, or otherwise continuously provide power to vehicle systems and subsystems. By way of contrast with the term “energy storage device” as defined herein, where a “battery” would be insufficient to move a traction motor, run a radiator fan for an extended period, or supply an auxiliary load for more than bare functionality or for more than a. short while, an “energy storage device” is able to perform one or more of these functions. Further, the energy storage device can be coupled to a dynamic braking system  150  (see, e.g.,  FIG. 2  and related description) to charge in response to a dynamic braking event using traction motors (in this instance, the dynamic braking system would be acting in a regenerative braking mode). An example of an energy storage device as defined herein would be a lithium ion cell array, a sodium metal halide cell array, a sodium sulfur cell array, a nickel metal hydride cell array, or a nickel cadmium cell array. 
     The term “radiator,” as defined herein, includes fluid-filled systems using heat dissipating fins/structures to transfer thermal energy from the fluid into the environment. Particularly, a radiator as defined herein is a device used to disperse the heat or thermal energy which the coolant has absorbed from an engine. A suitable radiator may contain a vertical- or horizontal-finned tubing section connecting a plurality of tanks. The radiator may be designed to hold a large amount of coolant in tubes or passages which give a large area in contact with the environment or atmosphere. The coolant, for example water mixed with antifreeze, may pass through the engine to be circulated by a water pump via a radiator hose to the radiator. For systems having plural radiators, the plural radiators may be parallel (in the same cooling circuit, but disposed in separate paths of the cooling circuit, where coolant that passes through one radiator of the circuit does not pass through another radiator of the circuit for a given loop of the coolant through the circuit); serial (in the same cooling circuit, and disposed in the same path of the cooling circuit, where coolant that passes through one radiator of the circuit passes through another radiator of the circuit for a given loop of the coolant through the circuit); or non-coupled, where the non-coupled radiators are part of separate and non-fluidly coupled cooling circuits. 
     In one embodiment, a mechanically decoupled, electric motor-driven fan(s) can reduce or eliminate one or more design constraints for a vehicle. Such constraints may include that the radiator and the fan are both mounted at the front end of a vehicle, and/or are inline with an engine, that the radiator has a roughly equal height and width, e.g., is square shaped, and that the radiator is compatibly configured for use with a single fan. 
     Design topologies for various embodiments disclosed herein may allow for one or more of the following features: multiple fans with the existing radiator; non-square radiators; multiple and distinct radiators; engine orientation flexibility; and multiple engines or engine-generator sets (“gen-sets”). 
     In one embodiment, multiple fans are used, in which each is run by an electric radiator fan motor coupled to an electrical power source such as an energy storage device. Multiple fans used with the existing radiator allows for fans with smaller diameters relative to a standard fan, increased uniformity of airflow through the radiator, targeted cooling or directional airflows, failure tolerant operation, improved equipment life, and modular fan replacements and repair. 
     The use of multiple, relatively smaller fans can reduce the relative size and cost of the thermal management system. In particular, while a single large fan may cause a flow of air through a radiator that is non-uniform, the use of multiple fans can cause multiple air flows through the same or similar radiator to improve the overall uniformity of air flow and the corresponding uniformity of heat transfer from the radiator to the flowing air. Multiple fans can each be directionally positioned to cause air to flow or circulate in areas of the radiator where additional cooling would be desirable. The use of multiple fans would allow for operation of the equipment and thermal management system, possibly at a reduced capacity, if less than all members of a fan set were to fail. The remaining operational fans of the fan set would continue to provide a cooling function for the radiator. This situation would allow for increased productivity as the vehicle need not be immediately sidelined until a replaced fan is acquired (as might be the case for a single-fan design). Even if the vehicle must be sidelined from full time duty for repair, a partially operating fan array may still allow the sidelined vehicle to reach a repair facility under its own power, obviating the need for the vehicle to be towed. Further, replacement of the failed fan unit may be less challenging than replacement of a conventional fan unit, since the failed fan unit would not require mechanical decoupling from the engine, but only electrical disconnect from the power source and decoupling from any support brackets. In addition, the smaller fan unit would be relatively lighter than the single larger fan of conventional fan units. 
     Non-square radiators could be used in a mechanically decoupled, electric motor driven system. Although a conventional square radiator may be optimized for the circular sweep of a single fan, the use of multiple fans allows for efficient use of non-square radiator configurations. For example, a non-square rectangular radiator (e.g., having a width that is twice its height) could accommodate two or more fans. Extending the width of the radiator, while retaining about the same overall surface area or cooling efficiency, may allow a design that allows reduction of the height of the radiator. 
     Multiple and distinct (or mutually exclusive) radiators could be used, each with its own fan(s). This configuration may allow mounting the radiators further away from the engine. For example, the radiator may be mounted other places on the vehicle rather than in front center. Suitable locations may include on the vehicle sides either in from of or behind the front tires. This would allow the engine to be placed relatively further forward. A forward located engine may enable better service access and a reduced clearance requirement in frame. Mounting the radiator away from the engine also allows for more efficient cooling of the engine because heat from the radiator is less likely to add heat back into the engine. 
     The engine orientation can also be changed, since it would not need to align a mechanical fan linkage with the fan. In one embodiment, the engine could be mounted laterally. In another embodiment, the engine could retain a longitudinal orientation relative to the vehicle, but could be reversed and/or moved backward relative to the chassis. Such an orientation may allow for a relatively smaller-in-diameter alternator in a horsecollar, for example. Such an alternator may allow reduction of the horsecollar size. 
     In one embodiment, a set of multiple engines may be used. These engines may be relatively smaller in size, and may be used as gen-sets. By gen-sets, it is contemplated that the engines will only be started and used when needed to provide power, such as in a hybrid vehicle. Thus, at low power usage some of the engines may be idled or stopped to reduce or eliminate fuel use and exhaust emissions. Further, decreasing engine size may allow for a greater degree of flexibility in the placement and location of each of the engines in the gen-set. In one alternative embodiment, the engines in the multi-engine set differ from each other in at least one aspect. Such aspects may include, as a difference relative to each other, the location, horsepower rating, type of fuel used, speed at which they are run (or optimized to be run efficiently), and the like. Where desirable, a cascade of smaller engines may be used where only the engines needed at any one time are in operation. Further, a smaller sized engine may be employed to provide an electrical charge to the energy storage device so that the energy storage device is at full capacity when needed. 
     In another embodiment, the fan need not be mechanically decoupled from the engine. For example, the energy storage device and motor may act as a supplement to the mechanical connection of the fan drive or vice versa, for example as a way to conserve electrical power while the engine is running while maintaining power to the fan when the engine is disengaged. 
       FIG. 1  is a schematic representation of a thermal management system  100  according to an example embodiment, The system  100  includes an engine  10 , an alternator  12  coupled to the engine, a radiator fan  20 , and a radiator  22 . The engine  10  may be directly coupled to the alternator via a belt, so that the engine mechanically drives the alternator for producing electricity. The engine-alternator coupling in this example is a direct mechanical linkage. The system  100  further includes an electric radiator fan motor  102  in electrical communication with the alternator  12 . The radiator fan motor  102  is mechanically decoupled from the engine. The radiator fan motor  102  drives the radiator fan  20  to create an air flow across the radiator  22 . “Mechanically decoupled” means there is no direct belt or other mechanical linkage from the engine  10  to the radiator fan  20 . 
       FIG. 2  is a schematic representation of a thermal management system  200  according to an example embodiment. The system  200  includes an engine  10 , an alternator  12  coupled to the engine, a radiator fan  20 , and a radiator  22 . The engine  10  may be directly coupled to the alternator via a belt, so that the engine mechanically drives the alternator for producing electricity. The engine-alternator coupling in this example is a direct mechanical linkage. A small cranking battery  14  is in electrical communication with the alternator, through which it is charged, and with the engine via a starter (not shown). A set of auxiliary load devices  16  may be coupled to the alternator as well. If the system  200  is in a vehicle, the vehicle may include a pair of wheels/tires  4  for alignment, and a vehicle chassis where the front of the vehicle is indicated by reference number  6 . The engine  10  may be located within the chassis space. 
     In the stem  200 , there is no direct mechanical or belt linkage from the engine  10  to the radiator fan  20 , and the system  200  further includes an electric radiator fan motor  102  that is electrically coupled to the alternator and to an energy storage device  106 . The energy storage device  106  is further coupled to the alternator, also, and optionally to a regenerative braking system or other dynamic braking system  150  that includes one or more traction motors  152 . (For example, the traction motors  152  may be mechanically coupled to the wheels  4 .) A suitable energy storage device includes, for example, a sodium metal halide battery, sodium sulfur, lithium ion battery, nickel metal hydride, nickel cadmium, and the like, as well as other energy storage mediums (capacitors, fuel cells, fly wheel devices, and the like). It should be noted that the energy storage devices listed here need not be entirely interchangeable, and may be selected based on the end use requirements and constraints. As used herein, dynamic braking refers to slowing a vehicle by converting vehicle mechanical energy to electrical energy (e.g., through traction motors of the vehicle), and regenerative braking to a type of dynamic braking where braking-generated electricity is selectively stored in an energy storage system (as opposed to dissipating the electricity or immediately using the electricity). 
     In an embodiment of the system  200 , electricity is generated or otherwise provided through dynamic braking of the dynamic braking system  150 . In a first mode of operation of the system  200 , as the electricity is being generated in dynamic braking, the electricity is routed to power the radiator fan motor  102 . In a second mode of operation of the system  200 , the electricity provided through dynamic braking is stored in the energy storage device  106  for use later in powering the radiator fan motor  102  (regenerative braking). 
     In an embodiment, the system  200  further comprises a controller  154  that can operate the radiator fan motor  102  when the engine  10  is not operating. (When the engine is not operating, the alternator is not providing electrical power to the radiator fan motor.) This can be realized by the controller  154  controlling the supplying of electricity from the energy storage device  106  to the radiator fan motor  102  when the engine is not operating. 
       FIG. 3  shows an example embodiment of a system  300  that differs from the system of  FIG. 2  in that the engine  10  is in reverse orientation. This is also a difference from mechanically driven radiator fan systems, which require a forward facing orientation of the engine due to the constraint of the placement of the radiator fan. 
       FIG. 4  shows an example embodiment of a system  400  that differs from the system of  FIG. 2  in that a single radiator fan motor is replaced by a first radiator fan motor  302  and at least one second radiator fan motor  304 , each of which drives a relatively smaller respective radiator fan  306 ,  310 . (In the case of plural second radiator fan motors  304 , each second radiator fan motor would drive a respective radiator fan.) 
     During operation, one or both of the fans (radiator fan motor and associated radiator fan) may be operated, depending on the available energy and on the desired cooling level. In alternative embodiments, a larger fan set may be used. The operation of the fans can affect the flow of air through the larger radiator. It is possible, then, to configure the fan orientation to achieve a different, and more effective, air flow through the radiator, and to increase thermal transfer in otherwise airflow starved regions of the radiator (relative to a single fan/single radiator). 
     Further, in the event of a failure of one or some of the fans, the other remaining fan(s) may be employed to ensure that the radiator is properly cooled. A warning signal for a fan failure can then be used to affect the operation of the vehicle (down rating but not shutting it off, for example) and can indicate a replacement is needed while not removing the vehicle from service. 
       FIG. 5  shows an example embodiment of a system  500  that differs from the systems of  FIGS. 3 and 4  in that the engine (in reverse orientation) is moved forward in the chassis space. Electric radiator fan motors  402 ,  404  are each electrically coupled to the alternator  12  and energy storage device  106 , and are mechanically coupled to respective relatively smaller fan blades  420   a,    420   b,  which are configured to draw an airflow through corresponding radiators  422   a,    422   b.  The fan blades and radiators are similar to the blades and radiators of the system of  FIG. 4 , but are positioned relatively differently in the vehicle chassis. Such a configuration would allow for a greater degree of flexibility in vehicle design. 
       FIG. 6  shows an example embodiment of a system  600  that differs from the system shown in  FIG. 5  in that the two illustrated radiator/radiator fan/radiator fan motor assemblies are oriented away from the front of the vehicle  6 . In an alternative embodiment, there is one assembly pointed toward the vehicle front  6 , while another is oriented away from the vehicle front. In one aspect, plural radiators are disposed in a vehicle chassis having a vehicle front end  6  and one or more vehicle sides that are perpendicular to the vehicle front end; at least one of the radiators is oriented towards one of the vehicle sides. 
       FIG. 7  shows an example embodiment of a system  700  that differs from the system shown in  FIG. 4  in that the engine orientation is skewed relative to the vehicle forward axis “V.” In the illustrated embodiment, the engine  10  is perpendicular to the vehicle front  6 . For clarity, the engine crankshaft may define an axis “A” that is parallel to a plane “P” defined by the vehicle front end  6 , wherein the plane is at a right angle to the vehicle forward axis “V.” 
       FIG. 8  shows an example embodiment of a system  800  that differs from the system shown in  FIG. 7  in that rather than the larger single engine, the system includes a set of two (or more) smaller gen-sets, each comprising an engine  710 ,  712  and an alternator/generator  714 ,  716 , respectively. In the illustrated embodiment, the gen-sets are both diesel, and can be operated in response to the system load, or projected system load, and the remaining state of charge of the energy storage device. 
     During operation, a system controller  154  checks signals from sensors (not shown) to determine such items as the state of charge of the energy storage device  106 , the operating condition of each engine in the gen-set, the engine temperature, the ambient temperature, and the like. In response to user input to direct the vehicle functions, the controller implements the electricity generating gen-sets to supply the power demanded, and/or replenish the energy storage device, and/or supply the aux load(s), and/or operate the radiator fan motors. The use is balanced against fuel consumption, emissions, noise, expected work loads, system status (for example, is each radiator fan still operating), and the like. 
     In an embodiment, a thermal management system (such as deployed in a vehicle) includes a radiator and a plurality of radiator fan motors associated with the radiator. Each radiator fan motor drives a respective fan for creating an air flow across the radiator. The composite airflow pattern created by the plural radiator fans differs from an airflow pattern that would be created if there was only a single radiator fan associated with the radiator. An example is illustrated in  FIG. 9 , which shows the front of a radiator  22   a,    22   b  in two different contexts. (The radiators  22   a ,  22   b  are the same, but are provided with different reference numbers in this figure to differentiate between two different radiator fan configurations for each.) In the first, for the radiator  22   a,  the system includes a first radiator fan motor and radiator fan  20   a.  The system further includes plural “second” radiator fan motors and radiator fans  20   b  (Three “second” radiator fan motors/radiator fans are shown in this example; there are four radiator fan motors/radiator fans in total) Each of the radiator fan motors  20   a,    20   b  is in electrical communication with the alternator, and each is mechanically decoupled from the engine. Each radiator fan motor and radiator fan  20   a,    20   b  creates a respective air flow  902  across the radiator  22   a.  In contrast, in the case of the radiator  22   b,  the radiator  22   b  is provided with a single radiator fan motor and radiator fan  20   c.  The single radiator fan motor and radiator fan  20   c  creates an airflow pattern  906  across the radiator  22   h.  As can be seen by comparing the two examples  22   a,    22   b  in  FIG. 9 , the plural radiator fan motors and radiator fans  20   a.    20   b ) of the radiator  22   a  are oriented relative to the radiator  22   a  to provide an airflow pattern  904  that differs from an airflow pattern  906  that would be created if there was only a single radiator fan  20   c  associated with the radiator. 
     By mechanically decoupling the radiator fans from the engine, a thermal management system (and vehicle incorporating such a system) may include, according to various embodiments: a single square radiator having plural radiator fan motors and radiator fans associated with the single square radiator; a single square radiator having three or more radiator fan motors and radiator fans associated with the single square radiator; a single non-square radiator having plural radiator fan motors and radiator fans associated with the single non-square radiator; a single non-square radiator having three or more radiator fan motors and radiator fans associated with the single non-square radiator; multiple square radiators, each at the same orientation relative to the vehicle or engine, and each having a single radiator fan motor and radiator fan; multiple square radiators, each at the same orientation relative to the vehicle or engine, and each having plural radiator fan motors and radiator fans (e.g., two fans, or three fans, or more than three fans); multiple square radiators, at different orientations relative to the vehicle or engine, and each having a single radiator fan motor and radiator fan, or plural radiator fan motors and radiator fans, or three or more radiator fan motors and radiator fans; multiple non-square radiators, each at the same orientation relative to the vehicle or engine, and each having plural (e.g., two, or three, or more than three) radiator fan motors and radiator fans; multiple non-square radiators, at different orientations relative to the vehicle or engine, and each having plural (e.g., two, or three, or more than three) radiator fan motors and radiator fans. In an embodiment, for a system with plural radiators, “different orientation” means that each radiator defines a primary plane based on its two maximum dimensions (typically width and height), and that the planes of at least two of the radiators are non co-planar (in one embodiment), or both non co. planar and non-parallel (in a second embodiment). 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, and plural radiators (e.g., a first radiator and one or more second radiators). The system also includes plural radiator fan motors (e.g., a first radiator fan motor and one or more second radiator fan motors). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are associated with the radiator, for creating air flow(s) across the radiator (e.g., the first radiator fan motor may be associated with the first radiator, for driving a first fan to create a first air flow across the first radiator, and the one or more second radiator fan motors may be respectively associated with the one or more second radiators, for driving a fan(s) to create an air flow(s) across the one or more second radiators.) Examples of such a system as shown in  FIGS. 5 and 6 . With reference to  FIG. 5 , a thermal management system  500  includes an engine  10  coupled to an alternator  12 , and plural radiators  422   a,    422   b  (e.g., a first radiator  422   a  and one or more second radiators  422   b ). The system also includes plural radiator fan motors  402 ,  404  (e.g. a first radiator fan motor  402  and one or more second radiator fan motors  404 ). The radiator fan motors  402 ,  404  are in electrical communication with the alternator  12 , and are mechanically decoupled from the engine  10 . For each radiator  422   a,    422   b,  one or more of the radiator fan motors are associated with the radiator, for mating air flow(s) across the radiator (e.g., the first radiator fan motor  402  may be associated with the first radiator  422   a,  for driving a first fan  420   a  to create a first air flow across the first radiator, and the one or more second radiator fan motors  404  may be respectively associated with the one or more second radiators  422   b,  for driving a fan(s)  420   b  to create an air flow(s) across the one or more second radiators.) With reference to  FIG. 6 , a thermal management system  600  includes an engine  10  coupled to an alternator  12 , and plural radiators  422   a,    422   b  (e.g., a first radiator  422   a  and one or more second radiators  422   b ). The system also includes plural radiator fan motors  402 ,  404  (e.g., a first radiator fan motor  402  and one or more second radiator fan motors  404 ). The radiator fan motors  402 ,  404  are in electrical communication with the alternator  12 , and are mechanically decoupled from the engine  10 . For each radiator  422   a,    422   b,  one or more of the radiator fan motors are associated with the radiator, for creating air flow(s) across the radiator (e.g., the first radiator fan motor  402  may be associated with the first radiator  422   a,  for driving a first fan  420   a  to create a first air flow across the first radiator, and the one or more second radiator fan motors  404  may be respectively associated with the one or more second radiators  422   b,  for driving a fan(s)  420   b  to create an air flow(s) across the one or more second radiators) 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, and plural radiators (e.g., a first radiator and one or more second radiators). The system also includes plural radiator fan motors (e.g., a first radiator fan motor and one or more second radiator fan motors). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are associated with the radiator, for creating air flow(s) across the radiator (e.g., the first radiator fan motor may be associated with the first radiator, for driving a first fan to create a first air flow across the first radiator, and the one or more second radiator fan motors may be respectively associated with the one or more second radiators, for driving a fan(s) to create an air flow(s) across the one or more second radiators.) Further, each of the radiators (e.g., the first radiator and the one or more second radiators) is disposed in a vehicle chassis having a vehicle front end, with each radiator being oriented towards the vehicle front end. For example, with reference to  FIG. 5 , two radiators  422   a,    422   b  are disposed in a vehicle chassis having a vehicle front end  6 , with each radiator being oriented towards the vehicle front end  6 . “Oriented towards” the vehicle front end means that the primary plane defined by each radiator based on its two maximum dimensions is: (i) in one aspect, directly oriented towards, meaning parallel to a plane defined by the vehicle front end  6  (see plane “P” in  FIG. 7 ); (ii) in another aspect, mostly oriented towards, meaning not parallel to a plane defined by the vehicle front end  6  but at or within 5 degrees of parallel; and (iii) in another aspect, generally oriented towards, meaning not parallel to a plane defined by the vehicle front end  6  but at or within 30 degrees of parallel. 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, and plural radiators (e.g., a first radiator and one or more second radiators). The system also includes plural radiator fan motors (e.g., a first radiator fan motor and one or more second radiator fan motors). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine, For each radiator, one or more of the radiator fan motors are associated with the radiator, for creating air flaw(s) across the radiator (e.g., the first radiator fan motor may be associated with the first radiator, for driving a first fan to create a first air flow across the first radiator, and the one or more second radiator fan motors may be respectively associated with the one or more second radiators, for driving a fan(s) to create an air flow(s) across the one or more second radiators). Further, each of the radiators (e.g., the first radiator and the one or more second radiators) is disposed in a vehicle chassis having a vehicle front end and one or more vehicle sides that are perpendicular to the vehicle front end. Further, at least one of the radiators is oriented towards the vehicle side. For example, with reference to  FIG. 6 , two radiators  422   a ,  422   b  are disposed in a vehicle chassis having a vehicle front end  6 , Each radiator  422   a,    422   b  is oriented towards a vehicle side (perpendicular to the vehicle front end  6 ). “Oriented towards” a vehicle side means that the primary plane defined by each radiator based on its two maximum dimensions is: (i) in one aspect, directly oriented towards, meaning parallel to a plane defined by the vehicle side, which is a plane perpendicular to a plane defined by the vehicle front (see plane “P” in  FIG. 7 ); (ii) in another aspect, mostly oriented towards, meaning not parallel to a plane defined by the vehicle side but at or within 5 degrees of parallel; and (iii) in another aspect, generally oriented towards, meaning not parallel to a plane defined by the vehicle side but at or within 30 degrees of parallel. 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, and plural radiators (e.g., a first radiator and one or more second radiators). The system also includes plural radiator fan motors (e.g., a first radiator fan motor and one or more second radiator fan motors). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are associated with the radiator, for creating air flow(s) across the radiator (e.g., the first radiator fan motor may be associated with the first radiator, for driving a first fan to create a first air flow across the first radiator, and the one or more second radiator fan motors may be respectively associated with the one or more second radiators, for driving a fan(s) to create an air flow(s) across the one or more second radiators). Further, each of the radiators is disposed m a vehicle chassis having a vehicle front end, and the engine is disposed between the radiators. Further, the engine is disposed about as proximate to the vehicle front end as the radiators. (Here, “about as proximate” means the end of the engine closest to the vehicle front end is within plus or minus 10% of the distance between the radiators and the vehicle front end.) For example, with reference to  FIG. 5 , each of the radiators  422   a,    422   b  is disposed in a vehicle chassis having a vehicle front end  6 , and the engine  20  is disposed between the radiators  422   a,    422   b.  Further, the engine is disposed about as proximate to the vehicle front end  6  as the radiators. As another example, with reference to  FIG. 6 , each of the radiators  422   a,    422   b  is disposed in a vehicle chassis having a vehicle front end  6 , and the engine  20  is disposed between the radiators  422   a,    422   b.  Further, the engine is disposed about as proximate to the vehicle front end  6  as the radiators. 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, and plural radiators (e.g., a first radiator and one or more second radiators). The system also includes plural radiator fan motors (e.g., a first radiator fan motor and one or more second radiator fan motors). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are associated with the radiator, for creating air flow(s) across the radiator (e.g., the first radiator fan motor may be associated with the first radiator, for driving a first fan to create a first air flow across the first radiator and the one or more second radiator fan motors may be respectively associated with the one or more second radiators, for driving a fan(s) to create an air flow(s) across the one or more second radiators.) Further, the radiators (e.g., the first radiator and the one or more second radiators) are disposed in a vehicle chassis having a vehicle front end and one or more vehicle sides that are perpendicular to the vehicle front end. Further, the engine is sideways relative to the vehicle front end with a crankshaft axis of the engine being parallel to a plane defined by the vehicle front end. See  FIG. 7  as an example of an engine being sideways relative to the vehicle front end with a crankshaft axis of the engine being parallel to a plane defined by the vehicle front end. 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, a radiator, and plural radiator fan motors (e.g., a first radiator fan motor and at least one second radiator fan motor). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. The plural radiator fan motors respectively drive a plurality of radiator fans for creating air flows across the radiator. The plurality of radiator fans are oriented relative to the radiator to provide an airflow pattern that differs from an airflow pattern that would be created if there was only a single radiator fan associated with the first radiator. See  FIG. 9  and its associated description as an example. The system may be deployed in a vehicle. Further, the system includes a controller  154  that communicates with and controls a respective operational state of each of the radiator fan motors. Example control modes effected by the controller include selectively initiating operation of the radiator fan motors (e.g., all radiator fan motors on, all off, some on and some off concurrently), and variable speed control. In an embodiment, with reference to  FIG. 10 , the controller  154  responds to an input signal (“Signal”) by initiating operation of one or more of the radiator fan motors, where the input signal represents a temperature of the engine “T 1 ”, a temperature of coolant of the engine “T 2 ”, an actual or predicted demand load “L” presented by one or more traction motors and/or auxiliaries in electrical communication with the engine and/or alternator, or an operational status “O” of one or more of the first radiator fan motor and the at least one second radiator fan motor. 
     In another embodiment, the controller  154  is additionally or alternatively operational to determine whether one of the radiator fan motors is operating (a determination of whether the radiator fan motor is currently running) or operational (a determination of whether the radiator fan motor would run if provided with electrical power). If it is determined that the radiator fan motor in question is not operating or operational, then the controller selects another one of the radiator fan motors to determine if that motor is operating or operational. 
     In another embodiment, with reference to  FIG. 11 , the controller  154  is additionally or alternatively operational to control a first one of the radiator fan motors to operate in response to an input signal indicating a temperature “T” (e.g., of an engine, or of coolant) above a determined first threshold level “R 1 ”. Concurrently, the controller  154  controls another, second one of the radiator fan motors to not operate when the input signal indicates that the temperature “T” is below a determined second threshold level “R 2 ”, which is higher than the first threshold level, Thus, when the input signal indicates that the temperature is below the second threshold level and above the first threshold level, only the first radiator fan motor operates, and when the input signal indicates that the temperature is above the second threshold level, both fans operate. In another embodiment, the controller controls another, third one of the radiator fan motors to not operate when the input signal indicates that the temperature is below a determined third threshold level, which is higher than the second threshold level. In another embodiment, for a system with three or more radiator fan motors associated with a radiator, when the input signal indicates a temperature below a threshold, the controller controls all the radiator fan motors to a non-operational state. Each time the input signal indicates a temperature rise by more than a predetermined amount, another one of the radiator fan motors is controlled into operation. Each time the input signal indicates a temperature fall by more than the predetermined amount, one of the operational radiator fan motors is controlled into non-operation. 
     In an embodiment, a thermal management system includes an engine coupled to an alternator, a radiator, and plural radiator fan motors (e g., a first radiator fan motor and at least one second radiator fan motor). The radiator fan motors are in electrical communication with the alternator, and are mechanically decoupled from the engine. The plural radiator fan motors respectively drive a plurality of radiator fans for creating air flows across the radiator, The plurality of radiator fans are oriented relative to the radiator to provide an airflow pattern that differs from an airflow pattern that would be created if there was only a single radiator fan associated with the first radiator. Further, the system includes plural gen-sets, with the engine and alternator comprising one of the gen-sets. (Each of the other gen-sets includes its own engine and alternator.) With reference to  FIG. 8  as an example, a thermal management system  800  includes art engine  710  coupled to an alternator  714 , a radiator  22 , and plural radiator fan motors  302 ,  304 . The engine  710  is part of a first gen-set that comprises the engine  710  and the alternator  714 . The system includes at least one other gen-set, in this example a gen-set comprising an engine  712  and alternator  716 . In another embodiment, the system (e.g., system  800 ) further includes a controller (e.g., controller  154 ) that communicates with and controls an operational state of each of the plurality of engines  710 ,  712  in the geo-sets. 
     In another embodiment, a thermal management system includes an engine coupled to an alternator, a plurality of radiators, and a plurality of radiator fan motors in electrical communication with the alternator The radiator fan motors are mechanically decoupled from the engine. The radiator fan motors are respectively associated with the plural radiators, for creating respective air flows across the radiators. The system further includes an energy storage device in electrical communication with the alternator and the radiator fan motors, and one or more traction motors in electrical communication with the energy storage device, the radiator fan motors, or both. In one mode of operation, electricity provided through dynamic braking is used to power one or more of the radiator fan motors upon generation of the electricity. In another mode of operation, the electricity provided through dynamic braking is stored in the energy storage device for use later in powering the radiator fan motors (regenerative braking). An example of such a system is shown in  FIG. 5 . Here, a thermal management system  500  includes an engine  10  coupled to an alternator  12 , a plurality of radiators  422   a,    422   b,  and a plurality of radiator fan motors  402 ,  404  in electrical communication with the alternator. The system further includes an energy storage device  106  in electrical communication with the alternator and the radiator fan motors, and one or more traction motors (not shown in this view, but see  152  in  FIG. 2 ) in electrical communication with the energy storage device, the radiator fan motors, or both. In one mode of operation, electricity provided through dynamic braking is used to power one or more of the radiator fan motors upon generation of the electricity. In another mode of operation, the electricity provided through dynamic braking is stored in the energy storage device for use later in powering the radiator fan motors (regenerative braking). 
     Another embodiment relates to a method for thermal management, in a vehicle or otherwise. The method comprises selectively providing electrical power to control a plurality of radiator fan motors in electrical communication with an alternator coupled to an engine. The engine includes one or more radiators. Each of the plurality of radiator fan motors is mechanically decoupled from the engine, and each of the radiator fan motors is coupled with a respective fan for creating an air flow across one of the one or more radiators. 
     In another embodiment of the method, the plurality of radiator fan motors are controlled based on an input signal indicative of a temperature. A first one of the plurality of radiator fan motors is controlled to operate in response to the input signal indicating that the temperature is above a determined first threshold level. Another, second one of the plurality of radiator fan motors is controlled to not operate when the input signal indicates that the temperature is below a determined second threshold level, the second threshold level being higher than the first threshold level. 
     In another embodiment, the method further comprises responding to the input signal, if the input signal is above the second threshold level, by controlling two or more of the plurality of radiator fan motors to operate. 
     In another embodiment, the method further comprises determining whether a first radiator fan motor of the plurality of radiator fan motors is operating or operational. if it is determined that the first radiator fan motor is not operating or operational, then a second radiator fan motor of the plurality of radiator fan motors is selected to determine if the second radiator fan motor is operating or operational. The method may further comprise initiating operation of an operational radiator fan motor if it is determined that one of the radiator fan motors is not operational. 
     In another embodiment, the method further comprises, if it is determined that one of the radiator fan motors is not operational, signaling that at least one of the radiator fan motors is not operational, and/or controlling an engine system in a manner sufficient to not generate more heat than can be dissipated by those of the plurality of radiator fan motors that remain operational, in conjunction with the radiator. (The engine system includes the engine, alternator, and radiator.) 
     Another embodiment relates to a method for thermal management, in a vehicle or otherwise. The method comprises selectively providing electrical power to control a plurality of radiator fan motors in electrical communication with an alternator coupled to an engine. The engine includes plural radiators. Each of the plurality of radiator fan motors is mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are uniquely associated with the radiator, for creating air flow across the radiator. (For example, “X” of the radiator fan motors may be associated with a first radiator, “Y” of the radiator fan motors may be associated with a second radiator, and so on, where “X” and “Y” represent mutually exclusive groups each comprising one or more of the radiator fan motors.) The plurality of radiator fan motors may be controlled based on an input signal indicative of a temperature. A first one of the plurality of radiator fan motors is controlled to operate in response to the input signal indicating that the temperature is above a determined first threshold level. Another, second one of the plurality of radiator fan motors is controlled to not operate when the input signal indicates that the temperature is below a determined second threshold level, the second threshold level being higher than the first threshold level. In another embodiment, the method further comprises responding to the input signal, if the input signal is above the second threshold level, by controlling two or more of the plurality of radiator fan motors to operate. 
     Another embodiment relates to a method for thermal management, in a vehicle or otherwise. The method comprises selectively providing electrical power to control a plurality of radiator fan motors in electrical communication with an alternator coupled to an engine. The engine includes plural radiators. Each of the plurality of radiator fan motors is mechanically decoupled from the engine. For each radiator, one or more of the radiator fan motors are uniquely associated with the radiator, for creating air flow across the radiator. The method further comprises determining whether a first radiator fan motor of the plurality of radiator fan motors is operating or operational. If it is determined that the first radiator fan motor is not operating or operational, then a second radiator fan motor of the plurality of radiator fan motors is selected to determine if the second radiator fan motor is operating or operational. The method may further comprises initiating operation of an operational radiator fan motor if it is determined that one of the radiator fan motors is not operational, hi another embodiment, the method further comprises, if it is determined that one of the radiator fan motors is not operational, signaling that at least one of the radiator fan motors is not operational, and/or controlling an engine system in a manner sufficient to not generate more heat than can be dissipated by those of the plurality of radiator fan motors that remain operational, in conjunction with the radiators. (The engine system includes the engine, alternator, and radiators.) 
     Another embodiment relates to a method for thermal management. The method comprises controlling a plurality of radiator fan motors based on an input signal indicative of a temperature. One of the plurality of radiator fan motors is controlled to operate in response to the input signal indicating that the temperature is above a determined first threshold level. Another one of the plurality of radiator fan motors is controlled to not operate when the input signal indicates that the temperature is below a determined second threshold level, the second threshold level being higher than the first threshold level. 
     Another embodiment relates to a method for thermal management. The method comprises determining whether a first radiator fan motor of a plurality of radiator fan motors is operating or operational. If the step of determining indicates that the first radiator fan motor is not operating or operational, then a second radiator fan motor of the plurality of radiator fan motors is selected to determine if the second radiator fan motor is operating or operational. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosed subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means limiting and are exemplary embodiments. The scope of the described subject matter should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-language equivalents of the respective terms “comprising” and “wherein:” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The embodiments described herein are examples of systems, structures and methods having elements corresponding to the elements of the invention recited in the claims. This written description may enable those of ordinary skill in the art to make and use embodiments having alternative elements that likewise correspond to the elements of the invention recited in the claims. The scope of the invention thus includes structures, systems and methods that do not differ from the literal language of the claims, and farther includes other systems, structures and methods with insubstantial differences from the literal language of the claims. While only certain features and embodiments have been illustrated and described herein, many modifications and changes may occur to one of ordinary skill in the relevant art The appended claims cover all such modifications and changes.