CONTROL SYSTEM AND METHOD FOR A FAN

Abstract

System (200), comprising: a control unit (202) with one or more processors (302) configured for: to operate a fan in a forward direction to cool a motor (212) in response to a measured motor temperature that is greater than a certain first motor threshold temperature, to determine an ice risk parameter of the engine (212); and to operate the fan in such a way that it rotates at least partially backwards based on the ice risk parameter; characterized by the fact that the control unit (202) is designed to determine the measured engine temperature and: to initiate the reverse rotation of the fan when the measured motor temperature is below the specified first motor threshold temperature, to stop the operation of the fan when the measured motor temperature is at or above the specified first motor threshold temperature, but below a specified second motor threshold temperature, and to rotate the fan in the forward direction when the measured motor temperature is at or above a certain second motor threshold temperature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No. 63 / 074,626 (published as US 2022 / 0 074 338 A1), filed on September 4, 2020, entitled “Control System and Method for a Fan”. BACKGROUNDTechnical field

[0002] The subject matter described relates to a system and method for operating and / or controlling a fan.

[0003] Designs known from the prior art are known, for example, from DE 10 2012 010 891 A1, DE 197 28 351 A1, US 2019 / 0 049 262 A1, US 2006 / 0 102 399 A1 or DE 11 2017 003 033 T5. Description of the technology

[0004] Some motors may be equipped with a cooling system to ensure the motor runs efficiently. The cooling system may include a cooling fan that dissipates heat from the motor, an inverter circuit that supplies power to the motor, or similar components.

[0005] When a vehicle travels through regions where the ambient temperature is below freezing, the use of a fan may be reduced due to the natural cooling of the surrounding air. Unfortunately, during periods of non-use, moisture in the air can cause ice to build up on the fan. Similarly, during snow or ice storms, ice can form on a fan's blades. The ice buildup on the fan can result in additional strain and greater energy requirements for the fan to rotate. In some cases, the ice can fill a gap between a fan blade and a housing, hindering and / or preventing the fan from rotating. As a result, the current required to rotate the fan can skyrocket as the fan motor attempts to rotate the fan and break up the ice.

[0006] The overload and power surges resulting from ice on the fan can lead to wear and tear and a shortened fan life. In some cases, it can cause the fan to malfunction. Fan malfunction can lead to insufficient cooling and damage to other components. Ice formation on the fan can therefore increase maintenance time, component wear, and costs. It may be desirable to have a different system and process than those currently available. SHORT DESCRIPTION

[0007] In one or more embodiments, a system is provided that may include a controller having one or more processors that may determine a temperature characteristic and operate the fan to cool a component based at least in part on the temperature characteristic, and operate the fan to rotate in reverse based on the temperature characteristic.According to the invention, the control unit is configured to determine the measured motor temperature and initiate reverse rotation of the fan when the measured motor temperature is below the specified first motor threshold temperature, to stop operation of the fan when the measured motor temperature is at or above the specified first motor threshold temperature but below a specified second motor threshold temperature, and to rotate the fan in the forward direction when the measured motor temperature is at or above a specified second motor threshold temperature.

[0008] In one or more embodiments, a control system is provided that may include one or more processors that determine an ice risk metric of an engine, operate a fan to cool the engine based on the ice risk metric, and operate the fan to rotate in reverse based on the ice risk metric when a measured engine temperature is below a certain first engine threshold temperature. According to the invention, the control system is configured to discontinue operation of the fan when the measured engine temperature is at or above the certain first engine threshold temperature but below a certain second engine threshold temperature, and to rotate the fan in a forward direction when the measured engine temperature is above the certain second engine threshold temperature.

[0009] In one or more embodiments, a method is provided that may include determining an ice risk characteristic of an engine, operating a fan to cool the engine based on the ice risk characteristic, and operating the fan to rotate in reverse based on the ice risk characteristic. The method is characterized by the following steps: initiating reverse rotation of the fan when the measured engine temperature is below the predetermined first engine threshold temperature, ceasing operation of the fan when the measured engine temperature is above the predetermined first engine threshold temperature but below a predetermined second engine threshold temperature, and rotating the fan in the forward direction when the measured engine temperature is above the predetermined second engine threshold temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The subject matter can be understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings. Fig. 1 shows a schematic representation of a vehicle system according to an embodiment of the invention; Fig. 2 shows a schematic representation of a control system according to an embodiment of the invention; Fig. 3 shows a schematic representation of a control unit according to an embodiment of the invention; and Fig. 4 shows a schematic block diagram of a method according to an embodiment of the invention. DETAILED DESCRIPTION

[0011] Embodiments of the subject matter described herein relate to a system and method for controlling and / or operating a fan. In one embodiment, a control unit monitors a temperature and / or humidity level. In one embodiment, the component is a motor. According to the invention, a measured motor temperature is determined, wherein, when the engine is below a certain first threshold motor temperature and a fan is not being used to cool the engine, a temperature and / or humidity measurement indicates that ice may form on the fan blades. At the same time, according to the embodiment of the invention, the vehicle control unit can cause the fan to rotate in reverse. This can occur at relatively low speeds. The rotation of the fan prevents moisture from settling on the fan blades.This can reduce or prevent ice formation on the blade. By rotating the fan in reverse and closing a damper between the fan and the motor, unintended and unwanted cooling of the motor can be reduced or prevented.

[0012] When the measured engine temperature rises and approaches a temperature at which the fan can be used to cool the engine, a first engine threshold temperature is exceeded. According to the invention, the vehicle control unit issues a command to stop the fan from operating in reverse. At this point, the flap can also be opened. When the engine reaches a second engine threshold temperature, according to the invention, the fan rotates in the forward direction to cool the engine. By stopping the fan from rotating in reverse before operating the fan in the forward direction, a current spike that would occur when switching the fan operating direction from reverse to forward can be avoided.Operating the fan at low reverse speed reduces ice buildup on the fan blades, reducing fan load, extending fan life, and reducing fan and motor maintenance costs.

[0013] Fig. 1 shows a schematic representation of a vehicle system 100. The vehicle system may travel along a route 104 from a starting or departure location to a destination or arrival location. The vehicle system may include a propulsion vehicle 108 and a non-propulsion vehicle 110 that are mechanically connected to travel the route together. The vehicle system may include at least one propulsion vehicle and optionally one or more non-propulsion vehicles. In one example, the individual vehicle may be a hybrid truck. As a hybrid truck, it may have a multi-fuel engine.

[0014] The propulsion-generating vehicle may generate traction to propel (e.g., pull or push) the non-propulsion-generating vehicle along the track. The propulsion-generating vehicle may include a propulsion subsystem that includes one or more traction motors and generates traction to propel the vehicle system.

[0015] In the illustrated embodiment, a control system 112 may be located entirely on the drive vehicle. However, in other embodiments, one or more components of the control system may be distributed across multiple vehicles, such as the vehicles that comprise the vehicle system. For example, some components may be distributed across two or more drive vehicles coupled together in a group or cluster. In an alternative embodiment, at least some of the components of the control system may be located remotely from the vehicle system, such as at a delivery location. The remote components of the control system may communicate with the vehicle system (and with components of the control system located thereon).

[0016] In the illustrated embodiment, the vehicle system is a rail vehicle system, where the track is a track formed by one or more rails. The prime mover is a locomotive, where the vehicle is a rail vehicle that transports passengers and / or freight. In other embodiments, the prime mover may be a type of rail vehicle other than a locomotive. In other embodiments, other suitable vehicle systems may include automobiles, watercraft, aircraft, mining vehicles, agricultural vehicles, or other off-highway vehicle (OHV) systems (e.g., a vehicle system not authorized and / or designed for travel on public roads), or the like. Although in some examples the track is described as a track, not all embodiments are limited to a rail vehicle traveling on a railroad track.One or more embodiments may be used in connection with non-rail vehicles and routes other than tracks, such as roads, paths, waterways, or the like.

[0017] In the example of Fig. 1, the vehicles of the vehicle system each comprise a plurality of wheels 120 engaging the track and at least one axle 122 connecting the left and right wheels (in Fig. 1 (only the left wheels are shown). The wheels and axles are optionally located on one or more bogies 118. The bogies can optionally be bogies with fixed axles, so that the wheels are non-rotatably connected to the axles, so that the left wheel rotates at the same speed, by the same amount and at the same times as the right wheel.

[0018] The vehicles in a vehicle system can be mechanically coupled to one another, for example, by couplings. For example, the drive vehicle can be mechanically coupled to the car via a coupling 123. Alternatively, the vehicles in a vehicle system can not be mechanically coupled to one another, but rather be logically or virtually connected. For example, the vehicles can be logically coupled to one another by communicating with one another to coordinate their movements, so that the vehicles travel together in a convoy or group as a vehicle system.

[0019] In Fig. 2 is a control system 200 for the vehicle system of Fig. 1. The control system may include a vehicle control unit 202 that can communicate with an engine control unit 204, such as an engine control unit (ECU), and an auxiliary control unit 206. The vehicle control unit may communicate with the engine control unit and the auxiliary control unit directly or via a network 210, such as an Ethernet network, a cellular network, over-the-air communication, or the like.

[0020] The engine control unit may be electrically connected to an engine 212 to provide input signals and receive output signals from the engine. For example, the engine may include temperature sensors 213 that detect a measured engine temperature. The engine may also include sensors that determine the temperature of working fluids within the engine or a circuit board within the engine. Suitable engines may be internal combustion engines, hybrid engines, electric or battery-powered motors, etc. In one example, the engine may be a stationary engine not used in connection with a vehicle. In one embodiment, if the engine is stationary, it may be controlled with a stationary control unit.

[0021] In each example, the temperature sensors may provide an ice risk metric. Such an metric may include a measured engine temperature, a temperature reading itself, a current level from which the temperature can be determined, the air temperature surrounding the engine, or the like. Based on the ice risk metric, either the engine control unit, the vehicle control unit, etc., may have one or more processors that determine the measured engine temperature based on the ice risk metric. The determination may be made using a lookup table, an algorithm, a mathematical equation, or the like.

[0022] The auxiliary power control unit, in one example, may be a fan control unit that may be operably coupled to an input device 214, such as one or more inverters. In one example, the input device may be electrically connected to a DC power source 216 or a DC link. The input device may power a first fan 218 and a second fan 220. In one example, the first fan may be an intercooler fan that may be operated to cool the engine or a component of the engine. The second fan may be a radiator fan that may be used to remove heat from the engine. In particular, the first fan and the second fan may operate as a heat exchanger system, with the intercooler fan providing cooling air while the radiator fan receives heated air.

[0023] In one example, the first and second fans are each variable speed fans, where the fans can differ in speed. Alternatively, a fixed speed fan can be provided, where the fan can have multiple settings, each setting is a specific speed, and the fan cannot be maintained at a speed between the multiple settings. In one embodiment, both the first and second fans can be selectively operated in both forward and reverse directions. Each fan can be operated in reverse. Each fan can be operated at a relatively low speed. In one example, each fan can rotate in reverse at a speed ranging from about twenty-five revolutions per minute (25 rpm) to about fifty revolutions per minute (50 rpm).In one example, each fan may rotate at a reverse speed ranging from about fifty revolutions per minute (50 rpm) to about seventy-five revolutions per minute (75 rpm). In another example, each fan may rotate at a speed less than the normal full forward capacity for rotation of the fan. In one embodiment, the controller may operate the fan in pulses to shake water from the fan. In one embodiment, the controller may operate the fan at a speed sufficient to discharge water from the fan.

[0024] The vehicle control unit may be operatively coupled to a valve 221, which in turn is coupled to a flap 222. The valve may be actuated to open and close the flap. The flap may be arranged between the fans and the engine or a component of the engine to be cooled. In particular, the flaps may serve to reduce or prevent the airflow from the fans to the engine, so that if a fan is operating at a time when the engine or a component of the engine does not need to be cooled, the flap blocks and resists the airflow from the fans to the engine or a component of the engine. The valve may thus be actuated to open and close the flap depending on the measured engine temperature.

[0025] During operation, the vehicle control unit receives a defrosting strategy. The vehicle control unit also receives inputs from the engine control unit related to an ice risk metric. The ice risk metric can include the measured engine temperature, the temperature of engine fluids, the ambient temperature of the vehicle, the temperature of a circuit board or components on a circuit board, or similar. Based on the ice risk metric, one or more of the fans are then instructed to operate accordingly.

[0026] For example, if the ambient temperature is below freezing and the engine is below a certain first engine threshold temperature, a fan can be instructed to operate in the reverse direction at low speed. This movement makes ice less likely to form on the fan blades, preventing ice buildup that would place additional strain on the fan during operation. If the measured engine temperature rises above the set first engine threshold temperature, this is an indication that engine cooling will soon be required. Therefore, if the first engine threshold temperature is exceeded, the vehicle control unit can instruct the fan control unit to stop the running fan. When a certain second engine threshold temperature is subsequently reached, cooling is required.Thus, the vehicle control unit can command the valve to open the flap and command the fan control unit to rotate a fan in the forward direction to begin cooling the engine.

[0027] In Fig. 3 shows an example of a control unit 300 that may be used in a vehicle system. In one example, the vehicle system is the vehicle system of Fig. 1. In another example, the control unit can be connected to the Fig. 2, which include the vehicle control unit, the engine control unit, the auxiliary control unit, etc., may be identical or different from them.

[0028] The control unit may include one or more processors 302, a storage unit (e.g., memory 304), and a transceiver 306 that may be used to send and receive communication signals. In one example, the transceiver may receive communication signals from an engine control unit, an auxiliary control unit, remote control units, sensors, or the like. The control unit may include multiple sensors 308, 310, and 312. Although three sensors are illustrated, in some examples, the control unit may not include any sensors and may only use information transmitted from another control unit or stored in the storage device. In other embodiments, more than three sensors may be provided. Each sensor may be used to monitor and receive information.The information may relate to an ice risk metric, an ambient temperature, and / or a humidity level. Humidity sensors may provide information about precipitation. For this purpose, a sensor may monitor the ambient temperature of the vehicle, the ambient temperature of the engine, the temperature of the fluid in the engine, the temperature of a circuit board or component of the engine's circuit board, the current used to rotate the fan, and the like. In other examples, a sensor may be used to determine the speed of a fan, the direction of rotation of a fan, the position of a damper, etc. In one embodiment, information about the ambient temperature, the humidity near the fan, and the amount of precipitation may be provided remotely (from outside the vehicle).

[0029] The control unit can not only monitor or receive the ice risk indicator, but also analyze the signals to determine the measured engine or vehicle temperature accordingly. The control unit can make determinations using a lookup table, algorithm, mathematical process or calculation, modeling, or similar. By determining the temperature, the control unit can operate the fan in a way that reduces and prevents ice formation on the fan, without causing current spikes when attempting to rotate a fan rotating in reverse to a forward direction.

[0030] Fig. 4 illustrates a method 400 for reducing ice formation on a fan. In one example, the vehicle, engine, control system, control unit, sensors, etc., used to perform the method are described in Fig. 1 to 3.

[0031] In step 402, an ice risk metric is determined. The ice risk metric may be a measured engine temperature, an ambient temperature, a predicted average ambient temperature for a trip, an engine fluid temperature, a circuit board temperature, a circuit board component temperature, an auxiliary device current, etc. The metric may be determined by receiving signals from sensors, a trip plan, a control unit, or the like, and using a lookup table, algorithm, mathematical process or calculation, modeling, or the like. The ice risk metric may, in one example, be a determination of the measured engine temperature itself or a determination of a metric related to the measured engine temperature.

[0032] In step 404, a fan is operated to rotate in reverse based on the ice risk metric when the fan is not operating to cool the engine. In one example, the fan may be an engine cooling fan, while in another example, the fan is an engine radiator fan. Alternatively, the fan may be both a cooling fan and a radiator fan. By rotating the fan in reverse, the air that the engine may be undesirably cooling may be drawn away from the engine. In one example, the fan rotates at a low speed, such as less than 75 rpm. In another example, the fan rotates at a speed between 25 rpm and 75 rpm. In yet another example, the fan may be operated at a variable speed, while in other examples, the fan is a non-variable speed fan.Rotating the fan at a low speed can reduce the amount of condensation on the fan or remove it through the rotating motion, thereby reducing the amount of ice that can form on the fan blades.

[0033] In step 406, a damper is closed based on the ice risk metric. In one example, the damper is closed when a measured engine temperature is below a first engine threshold temperature. Specifically, when the fan is operating and rotating in reverse, the damper is closed to prevent air from flowing over the engine or any engine component and unintentionally cooling the engine.

[0034] In step 408, the fan stops rotating in reverse based on the ice risk metric. When the engine is running and the measured engine temperature approaches the temperature at which the cooling fan rotates forward to cool the engine, the vehicle control unit sends a command signal to stop the fan rotating in reverse. Consequently, the fan stops rotating in reverse at a certain first engine threshold temperature, allowing the fan to begin rotating forward when a second engine threshold temperature is reached.

[0035] In step 410, the damper is opened based on the ice risk metric. In one example, the damper is opened when the determined first engine threshold temperature is reached, in anticipation of the fan rotating in the forward direction for cooling. Alternatively, the damper is opened upon reaching the second engine threshold temperature, when the fan begins rotating in the forward direction. In another example, the damper is opened at a time between the determined first engine threshold temperature and the second engine threshold temperature.By opening at a time between the first motor threshold temperature and the second motor threshold temperature, the fan can be given time to stop rotating in reverse and cool the motor prematurely, while ensuring that the damper is open when the fan begins rotating in the forward direction.

[0036] In step 412, the fan is turned on to cool the engine based on the ice risk metric. In one example, the fan is turned on when the second engine threshold temperature is reached. Thus, the fan runs almost continuously when there is a risk of ice formation. The term "almost continuously" refers to the rotation of the fan in either the reverse or forward direction, except during the time when the measured engine temperature is between the first engine threshold temperature and the second engine threshold temperature. Because the fan is operated to rotate almost continuously, water can be removed from the fan blade and ice formation can be reduced and / or prevented. Therefore, when the fan is operated in the forward direction, ice does not cause additional stress on the fan blades, which reduces wear on the fan.This increases the fan's lifespan, reduces fan maintenance, and ensures the engine can be cooled, preventing engine failures while driving or on the track and unwanted downtime. In one embodiment, the fan does not run at full power, but rather in a slower "idle" or "freewheel" mode. In this mode, the fan rotates fast enough to remove water, snow, and / or ice, but not as fast as when cooling a component.

[0037] In one or more embodiments, a system is provided that may include a controller that may have one or more processors that may determine a temperature characteristic of a component (e.g., a motor), operate the fan to cool the component based on the temperature characteristic, and operate the fan to rotate in reverse based on the temperature characteristic.

[0038] Optionally, the control unit may determine a measured engine temperature based on the ice risk metric and rotate the fan in reverse when the measured engine temperature is below a certain first engine threshold temperature, cease operation of the fan when the measured engine temperature is at or above the certain first engine threshold temperature and below a second engine threshold temperature, and rotate the fan in forward direction when the measured engine temperature is at or above the second engine threshold temperature. Optionally, the one or more processors of the vehicle control unit may receive signals from temperature sensors connected to a vehicle in which the engine is housed and from sensors connected to a fluid system connected to the engine.

[0039] Optionally, the one or more processors of the vehicle control unit may determine the ice risk metric from a travel plan input to or communicated to the vehicle control unit. Optionally, the one or more processors of the vehicle control unit may communicate with a fan control unit operable to operate the fan. Optionally, the one or more processors of the vehicle control unit may communicate with an engine control unit to receive signals from the engine used to determine the ice risk metric of the engine. Optionally, the system may also include dampers disposed between the fan and the engine to reduce airflow from the fan over the engine.Optionally, the one or more processors of the vehicle control unit may be in communication with a valve that can actuate the flaps to close the flaps below a first engine threshold temperature and open the flaps above the first engine threshold temperature. Optionally, the fan may be a variable-speed fan. Optionally, the fan may comprise a cooling fan and a radiator fan.

[0040] In one or more embodiments, a control system is provided that may include one or more processors that may determine an ice risk metric of an engine, operate a fan to cool the engine based on the ice risk metric, and operate the fan to rotate in reverse based on the ice risk metric when a measured engine temperature is below a certain first engine threshold temperature. Optionally, the one or more processors may determine the measured engine temperature based on the ice risk metric, cease operation of the fan when the measured engine temperature is at or above the certain first engine threshold temperature and below a second engine threshold temperature, and rotate the fan in a forward direction when the measured engine temperature is at or above the second engine threshold temperature.

[0041] Optionally, the one or more processors may receive signals from temperature sensors to determine the ice risk metric. Optionally, the one or more processors may determine the ice risk metric from a travel plan input to or transmitted to the one or more processors. Optionally, the one or more processors may close dampers located between the engine and a fan below the determined first engine threshold temperature and open the dampers above the first engine threshold temperature.

[0042] In one or more embodiments, a method may be provided that may include determining an ice risk metric of an engine, operating a fan to cool the engine based on the ice risk metric, and operating the fan to reverse rotation based on the ice risk metric. Optionally, the ice risk metric may be a measured engine temperature or a parameter used to determine the measured engine temperature.

[0043] Optionally, the method may include receiving signals from at least one temperature sensor and / or humidity sensor to determine the ice risk metric. Optionally, the method may include communicating with an engine control unit to receive signals from the engine used to determine the ice risk metric. Optionally, the method may include receiving an input at an interface or communication from a remote control to determine the ice risk metric.

[0044] As used herein, the terms "processor" and "computer," as well as related terms such as "processing device," "computing device," and "controller," are not limited to those integrated circuits commonly referred to as computers, but rather refer to a microcontroller, a microcomputer, a programmable logic controller (PLC), a field-programmable gate array, an application-specific integrated circuit, and other programmable circuits. Suitable memory may be, for example, a computer-readable medium. A computer-readable medium may be, for example, random access memory (RAM) or a computer-readable non-volatile medium such as flash memory.The term "non-transitory computer-readable medium" means a tangible, computer-based device used for the short- and long-term storage of information, such as computer-readable instructions, data structures, program modules and sub-modules, or other data in any device. Therefore, the methods described herein may be encoded as executable instructions embodied in a tangible, non-transitory computer-readable medium, including, without limitation, a storage device and / or a memory device. When executed by a processor, such instructions cause the processor to perform at least some of the methods described herein.As such, the term includes tangible, computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and non-volatile media, as well as removable and non-removable media, such as firmware, physical and virtual memory, CD-ROMs, DVDs, and other digital sources, such as a network or the Internet.

[0045] The singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. "Optionally" means that the event or circumstance subsequently described may or may not occur, and that the description may include cases in which the event occurs and cases in which it does not occur. Approximate language, as used herein in the description and claims, may be used to modify any quantitative representation that may permissibly vary without changing the basic function to which it relates. Accordingly, a value modified by one or more of the terms "approximately," "substantially," and "approximately" need not be limited to the precise value stated.At least in some cases, the approximate formulation may correspond to the accuracy of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, and such ranges may be identified and include all subranges contained therein, unless the context or language indicates otherwise.

[0046] In this written description, the embodiments, including the best mode, are disclosed by way of example to enable one of ordinary skill in the art to practice the embodiments, including making and using devices or systems and performing integrated methods. The claims define the patentable scope of the disclosure and include further examples that one of ordinary skill in the art might devise. Such further examples are intended to be within the scope of the claims if they include design elements that do not differ from the literal language of the claims, or if they include equivalent design elements with insubstantial differences from the literal language of the claims. List of reference symbols 100 vehicle system 104 route 108 propulsion vehicle 110 non-propulsion vehicle 112 Tax system 118 bogie 120 wheels 122 Axis 123 Clutch 200 tax system 202 Vehicle control unit 204 Engine control unit 206 Auxiliary control unit 210 Network 212 engine 213 Temperature sensor 214 Entrance device 216 DC source 218 first fan 220 second fan 221 Valve 222 flap 300 control unit 302 processor 304 memory 306 transceivers 308 Sensor 310 Sensor 312 Sensor 400 Methods for reducing ice formation on a fan

Claims

[1] System (200), comprising: a control unit (202) having one or more processors (302) configured to: operate a fan in a forward direction to cool a motor (212) in response to a measured motor temperature that is greater than a certain first motor threshold temperature, to determine an ice risk characteristic of the engine (212); and operate the fan in such a way that it rotates at least partially in reverse based on the ice risk indicator; characterized by , that the control unit (202) is configured to determine the measured engine temperature and: to initiate the reverse rotation of the fan if the measured motor temperature is below the specified first motor threshold temperature, to stop the operation of the fan when the measured motor temperature is at or above the determined first motor threshold temperature but below a determined second motor threshold temperature, and to rotate the fan in the forward direction when the measured motor temperature is at or above a certain second motor threshold temperature. [2] The system (200) of claim 1, wherein the control unit (202) is configured to receive signals from temperature sensors (213) coupled to a vehicle (108) in which the engine (212) is housed and from sensors coupled to a fluid system coupled to the engine (212). [3] The system (200) of claim 1 or 2, wherein the control unit (202) is configured to determine the ice risk metric based at least in part on i.) a travel plan input to the control unit (202), ii.) information communicated to the control unit (202) from outside the vehicle (108), or both i.) and ii.). [4] The system (200) of any one of claims 1 to 3, wherein the control unit (202) is configured to operate the fan at a speed relatively slower than the full operating speed of the fan, but sufficiently fast to drain water from the fan. [5] The system (200) of any one of claims 1 to 4, wherein the control unit (202) is configured to operate the fan in pulses sufficient to shake water out of the fan. [6] The system (200) of any one of claims 1 to 5, further comprising dampers (222) disposed between the fan and the motor (212) to reduce the airflow from the fan over the motor (212). [7] The system (200) of claim 6, wherein the control unit (202) communicates with a valve (221) configured to actuate the flaps (222) to close the flaps (222) below the first engine threshold temperature and to open the flaps (222) above the first engine threshold temperature. [8] The system (200) of any one of claims 1 to 7, wherein the fan is a variable speed fan. [9] The system (200) of any one of claims 1 to 8, wherein the fan is one of a plurality of fans, and the plurality includes a cooling fan (218) and a radiator fan (220). [10] Control system (300) comprising one or more processors (302) configured to: to determine an ice risk characteristic of an engine (212); operate a fan to cool the engine (212) when a measured engine temperature is above a certain first engine threshold temperature; and operate a fan to rotate in reverse based at least in part on the ice risk metric when a measured motor temperature is below the determined first motor threshold temperature; characterized by , that the control system (300) is configured to stop operation of the fan when the measured motor temperature is at or above the determined first motor threshold temperature but below a determined second motor threshold temperature, and to rotate the fan in the forward direction when the measured motor temperature is above the specified second motor threshold temperature. [11] The control system (300) of claim 10, wherein the one or more processors (302) are configured to determine the measured motor temperature, to cease operation of the fan when the measured motor temperature is at or above the determined first motor threshold temperature and below a second motor threshold temperature, and to rotate the fan in the forward direction when the measured motor temperature is at or above the second motor threshold temperature. [12] The control system (300) of claim 10 or 11, wherein the one or more processors (302) are configured to receive signals from temperature sensors (213) to determine the ice risk characteristic. [13] The control system (300) of any one of claims 10 to 12, wherein the one or more processors (302) are configured to determine the ice risk metric based at least in part on a travel plan input to the control system (300) and / or information remotely communicated to the one or more processors (302). [14] The control system (300) of any one of claims 10 to 13, wherein the one or more processors (302) are configured to close the flaps (222) arranged between the motor (212) and a fan below the first motor threshold temperature and to open the flaps (222) above the first motor threshold temperature. [15] Method (400) comprising: Determining the ice risk characteristic of an engine; Operating a fan to cool the engine based on a measured engine temperature that is greater than a certain first engine threshold temperature; and Operating the fan to rotate in reverse based at least in part on the ice risk indicator; characterized by Initiate reverse fan operation when the measured motor temperature is below the specified first motor threshold temperature, Stopping the operation of the fan when the measured motor temperature is above the determined first motor threshold temperature but below a determined second motor threshold temperature, and Rotate the fan in the forward direction when the measured motor temperature is above the specified second motor threshold temperature. [16] The method (400) of claim 15, wherein the ice risk metric is based at least in part on the measured engine temperature, a parameter used to determine the measured engine temperature, an ambient temperature near the engine, and a level of ambient humidity near the engine. [17] The method (400) of claim 15 or 16, further comprising receiving signals from at least one temperature sensor to determine the ice risk characteristic, the measured engine temperature, or both. [18] The method (400) of any one of claims 15 to 17, further comprising communicating with an engine control unit (204) to receive signals used to determine the ice risk metric. [19] The method (400) of any one of claims 15 to 18, further comprising receiving an input at an interface or a communication from a remote source to determine the ice risk metric.

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