Patent Publication Number: US-10323564-B2

Title: Systems and methods for increasing temperature of an internal combustion engine during a cold start including low coolant flow rates during a startup period

Description:
FIELD 
     The present disclosure relates to cooling systems for internal combustion engines, and more particularly to systems for increasing temperatures of an engine during startup. 
     BACKGROUND 
     The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     An internal combustion engine combusts air and fuel within cylinders to drive pistons and produce drive torque. Subsequent to startup and when a temperature of the engine is greater than a first threshold, coolant is circulated through one or more cylinder heads of the engine and an engine block and may also be circulated through an integrated exhaust manifold. The coolant is circulated to prevent the temperature of the engine from exceeding a second threshold. The temperature and/or flow rate of the coolant may be adjusted to control cooling of the engine, engine block, and integrated exhaust manifold and/or maintain predetermined temperatures of the engine, engine block and integrated exhaust manifold. The predetermined temperatures may be (i) greater than the first threshold, (ii) less than the second threshold, and (iii) maintained to maximize fuel efficiency of the engine. 
     SUMMARY 
     A system is provided and includes a startup module, a load module, a flow module, and a peak estimation module. The startup module is configured to (i) during a startup period of an engine or in response to a startup of the engine, receive a temperature signal from a first temperature sensor, and (ii) generate a first condition signal based on the temperature signal. The load module is configured to (i) determine a load on the engine, and (ii) generate a second condition signal. The flow module is configured to, if the first condition signal indicates a temperature of the engine is less than a first predetermined temperature, and if the second condition signal indicates the load is less than a predetermined threshold, operate a pump to circulate coolant during the startup period of the engine. The peak estimation module is configured to estimate a temperature of a hottest metal location on the engine. The flow module is configured to increase a speed of the pump if (i) the temperature of the hottest metal location is greater than a second predetermined temperature, or (ii) the load is greater than or equal to the predetermined threshold. 
     In other features, a system is provided and includes a startup module, a load module, a flow module and a peak estimation module. The startup module is configured to (i) during a startup period of an engine or in response to a startup of the engine, receive a temperature signal from a first temperature sensor, and (ii) generate a first condition signal based on the temperature signal. The load module is configured to (i) determine an amount of output torque of on the engine, and (ii) generate a second condition signal. The flow module is configured to, if the first condition signal indicates a temperature of the engine is less than a first predetermined temperature, and if the second condition signal indicates the amount of output torque is less than a predetermined threshold, operate a pump to circulate coolant during the startup period of the engine. The peak estimation module is configured to estimate a temperature of a hottest metal location on the engine. The flow module is configured to increase a speed of the pump if (i) the temperature of the hottest metal location is greater than a second predetermined temperature, or (ii) the amount of output torque is greater than or equal to the predetermined threshold. 
     In other features, a method is provided and includes: during a startup period of an engine or in response to a startup of the engine, receive a temperature signal from a first temperature sensor and generate a first condition signal based on the temperature signal; determining a load on the engine and generating a second condition signal based on the load; if the first condition signal indicates a temperature of the engine is less than a first predetermined temperature, and if the second condition signal indicates the load is less than a predetermined threshold, operating a pump to circulate coolant during the startup period of the engine; estimating a temperature of a hottest metal location on the engine; and increasing a speed of the pump if (i) the temperature of the hottest metal location is greater than a second predetermined temperature, or (ii) the load is greater than or equal to the predetermined threshold. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a view of multiple plots illustrating a reduction in fuel efficiency as a result of increased coolant flow rate and corresponding parameters; 
         FIG. 2  is a functional block diagram of an example of a powertrain system incorporating a temperature module according to the present disclosure; 
         FIG. 3  is a functional block diagram of an example of an engine system and corresponding temperature control system incorporating the temperature module according to the present disclosure; 
         FIG. 4  is a functional block diagram of an example of the temperature module of  FIGS. 2-3 ; 
         FIG. 5  is a flow diagram illustrating a temperature control method for coolant of an engine according to the present disclosure; and 
         FIG. 6  is a pressure versus flow rate plot indicating an example operating range for the temperature module of  FIGS. 2-4 . 
     
    
    
     In the drawings, reference numbers may be reused to identify similar and/or identical elements. 
     DETAILED DESCRIPTION 
     During a cold start of an engine, coolant in the engine may be prevented from flowing (referred to as ‘zero coolant flow’) to allow the engine to warmup quickly. Zero coolant flow algorithms including temperature prediction models can be used to estimate temperatures of the engine. The zero coolant flow algorithms can be difficult to implement and can require a significant amount of calibration time and effort. For example, the temperature prediction models may be based on engine power, startup temperatures, catalyst warming states, and intake air temperatures and may be created to predict temperatures of the engine. Inaccuracies in these prediction models can result in coolant boiling and possible engine erosion. 
     Coolant flow rates and temperatures of an engine including temperatures of coolant flowing through an engine can vary during operation of the engine. This variation can affect fuel efficiency of the engine. As an example, during a cold startup of an engine when a temperature of the engine is less than a predetermined temperature, as coolant flow is increased, fuel efficiency decreases. This is illustrated by the plots of  FIG. 1 .  FIG. 1  shows a fuel efficiency versus engine coolant flow rate plot (or first plot), a combustion wall temperature versus time plot (or second plot), and a vehicle speed versus time plot (or third plot). The first plot, the second plot and the third plot are related and associated with the same example application. 
     The first plot includes a fuel efficiency versus engine coolant flow rate curve  10  illustrating that as a coolant flow rate increases, fuel efficiency decreases. The first plot also shows that when the flow rate is greater than a cutoff (or transition) point, the fuel efficiency substantially decreases. This is shown by the drop in fuel efficiency between points  12 ,  14 . Systems and methods are disclosed below that maintain coolant flow rates between zero and a predetermined flow rate (e.g., a flow rate less than or equal to 2 liters per minute (L/min) for the application associated with the first plot) during and/or after a startup of an engine. The second plot shows combustion wall temperature curves  20 ,  22 ,  24 ,  26  for different flow rates. The curves  20 ,  22 ,  24 ,  26  collectively illustrate as flow rates increase, combustion wall temperatures of the engine decrease. In the example shown, the curves  20 ,  22 ,  24 ,  26  correspond to the flow rates respectively of 15 L/min, 6.0 L/min, 1.5 L/min, and 0 L/min. The third plot includes a vehicle speed versus time curve  30  showing that changes in vehicle speed can be related to, proportional to and/or similar to changes in combustion wall temperature. 
     Systems and methods are disclosed herein for controlling the temperature of coolant in an engine during and/or after startup of the engine. This includes restricting and/or providing a minimum flow rate during and/or after a startup (referred to as the ‘warm-up period’ or ‘cold startup period’). This increases warm-up rates of the engine while maintaining high fuel efficiency during the warm-up period. Coolant is past at a slow rate across hot spots in an engine during the warm-up period without removing excessive thermal energy. Feedback control is provided to enable a quick warm-up without a fuel efficiency penalty. 
       FIG. 2  shows a powertrain system  40  that includes an engine system  42  and a transmission system  44 . The engine system  42  includes an engine  46  and an engine control module (ECM)  47 . The transmission system  44  includes a transmission control module (TCM)  51  and a transmission  53 . The ECM  47  includes a temperature module  50 , which controls operating temperatures of the engine  46 . 
     The powertrain system  40  includes the engine  46  that combusts an air/fuel mixture to produce drive torque for a vehicle based on a driver input from a driver input module  104 . Air is drawn into an intake manifold  110  through a throttle valve  112 . The ECM  47  controls a throttle actuator module  116 , which regulates opening of the throttle valve  112  to control the amount of air drawn into the intake manifold  110 . A brake booster  106  draws vacuum from the intake manifold  110  when the pressure within the intake manifold  110  is less (i.e., is a greater vacuum) than a pressure within the brake booster  106 . The brake booster  106  assists a vehicle user in applying brakes of the vehicle. 
     Air from the intake manifold  110  is drawn into cylinders (one is shown) of the engine  46 . The ECM  47  may instruct a cylinder actuator module  120  to selectively deactivate some of the cylinders (e.g., cylinder  118 ), which may improve fuel economy under certain engine operating conditions. During an intake stroke, air from the intake manifold  110  is drawn into the cylinder  118  through an intake valve  122 . The ECM  47  controls a fuel actuator module  124 , which regulates fuel injection to achieve a desired air/fuel ratio. Fuel may be injected into the intake manifold  110  at a central location or at multiple locations, such as near the intake valve  122  of each of the cylinders. In various implementations (not shown), fuel may be injected directly into the cylinders or into mixing chambers associated with the cylinders. The fuel actuator module  124  may halt injection of fuel to cylinders that are deactivated. 
     The injected fuel mixes with air and creates an air/fuel mixture in the cylinder  118 . During the compression stroke, a piston (not shown) within the cylinder  118  compresses the air/fuel mixture. Based on a signal from the ECM  47 , a spark actuator module  126  energizes a spark plug  128  in the cylinder  118 , which ignites the air/fuel mixture. The timing of the spark may be specified relative to the time when the piston is at its topmost position, referred to as top dead center (TDC). 
     The spark actuator module  126  may be controlled by a timing signal specifying how far before or after TDC to generate the spark. Because piston position is directly related to crankshaft rotation, operation of the spark actuator module  126  may be synchronized with crankshaft angle. In various implementations, the spark actuator module  126  may halt provision of spark to deactivated cylinders. 
     During the combustion stroke, the combustion of the air/fuel mixture drives the piston down, thereby driving the crankshaft. During the exhaust stroke, the piston begins moving up from bottom dead center (BDC) and expels the byproducts of combustion through an exhaust valve  130 . The byproducts of combustion are exhausted from the vehicle via an exhaust system  54 . 
     The exhaust system  54  includes a catalyst  136  and a particulate filter  56 . A catalyst  136  receives exhaust gas output by the engine  46  and reacts with various components of the exhaust gas. For example only, the catalyst may include a three-way catalyst (TWC), a catalytic converter, or another suitable exhaust catalyst. The particulate filter  56  may be downstream from the catalyst  136  and filters soot from an exhaust gas received from the catalyst  136 . 
     The intake valve  122  may be controlled by an intake camshaft  140 , while the exhaust valve  130  may be controlled by an exhaust camshaft  142 . The cylinder actuator module  120  may deactivate the cylinder  118  by disabling opening of the intake valve  122  and/or the exhaust valve  130 . In various other implementations, the intake valve  122  and/or the exhaust valve  130  may be controlled by devices other than camshafts, such as electromagnetic actuators. 
     The times at which the intake and exhaust valves  122 ,  130  are opened may be varied with respect to piston TDC by intake and exhaust cam phasers  148 ,  150 . A phaser actuator module  158  may control the intake and exhaust cam phasers  148 ,  150  based on signals from the ECM  47 . 
     The powertrain system  40  may include a boost device that provides pressurized air to the intake manifold  110 . For example,  FIG. 1  shows a turbocharger including a hot turbine  160 - 1  that is powered by hot exhaust gases flowing through the exhaust system  54 . The turbocharger also includes a cold air compressor  160 - 2 , driven by the turbine  160 - 1 , which compresses air leading into the throttle valve  112 . In various implementations, a supercharger (not shown), driven by the crankshaft, may compress air from the throttle valve  112  and deliver the compressed air to the intake manifold  110 . 
     A wastegate  162  may allow exhaust to bypass the turbine  160 - 1 , thereby reducing the boost (the amount of intake air compression) of the turbocharger. The ECM  47  may control the turbocharger via a boost actuator module  164 . The boost actuator module  164  may modulate the boost of the turbocharger by controlling the position of the wastegate  162 . 
     The powertrain system  10  may include an exhaust gas recirculation (EGR) valve  170 , which selectively redirects exhaust gas back to the intake manifold  110 . The EGR valve  170  may be located upstream of the turbocharger&#39;s turbine  160 - 1 . The EGR valve  170  may be controlled by an EGR actuator module  172 . 
     The powertrain system  40  may measure the speed of the crankshaft (i.e., engine speed) in revolutions per minute (RPM) using an RPM sensor  178 . Temperature of engine oil may be measured using an oil temperature (OT) sensor  180 . Temperature of engine coolant may be measured using an engine coolant temperature (ECT) sensor  182 . The ECT sensor  182  may be located within the engine  46  or at other locations where the coolant is circulated, such as a radiator (not shown). A temperature of the engine may be indicated as T ENG . The temperature of the engine T ENG  may be equal to or determined based on the engine oil temperature and/or the engine coolant temperature. 
     The pressure within the intake manifold  110  may be measured using a manifold absolute pressure (MAP) sensor  184 . The mass flow rate of air flowing into the intake manifold  110  may be measured using a mass air flowrate (MAF) sensor  186 . In various implementations, the MAF sensor  186  may be located in a housing that also includes the throttle valve  112 . 
     The throttle actuator module  116  may monitor the position of the throttle valve  112  using one or more throttle position sensors (TPS)  190 . The ambient temperature of air being drawn into the engine  16  may be measured using an intake air temperature (IAT) sensor  192 . The ECM  47  may use signals from one or more of the sensors to make control decisions for the powertrain system  40 . 
     The ECM  47  may communicate with the TCM  51  to coordinate shifting gears (and more specifically gear ratio) in a transmission (not shown). For example, the ECM  47  may reduce engine torque during a gear shift. The ECM  47  may communicate with a hybrid control module  196  to coordinate operation (i.e., torque output production) of the engine  46  and an electric motor  198 . 
     The electric motor  198  may also function as a generator, and may be used to produce electrical energy for use by vehicle electrical systems and/or for storage in an energy storage device (e.g., a battery). The production of electrical energy may be referred to as regenerative braking. The electric motor  198  may apply a braking (i.e., negative) torque on the engine  46  to perform regenerative braking and produce electrical energy. The powertrain system  40  may also include one or more additional electric motors. In various implementations, various functions of the ECM  47 , the TCM  51 , and the hybrid control module  196  may be integrated into one or more modules. 
     Each system that varies an engine parameter may be referred to as an engine actuator. Each engine actuator receives an associated actuator value. For example, the throttle actuator module  116  may be referred to as an engine actuator and the throttle opening area may be referred to as the associated actuator value. In the example of  FIG. 2 , the throttle actuator module  116  achieves the throttle opening area by adjusting an angle of the blade of the throttle valve  112 . 
     Similarly, the spark actuator module  126  may be referred to as an engine actuator, while the associated actuator value may be the amount of spark advance relative to cylinder TDC. Other actuators may include the cylinder actuator module  120 , the fuel actuator module  124 , the phaser actuator module  158 , the boost actuator module  164 , and the EGR actuator module  172 . For these engine actuators, the associated actuator values may include: a number of activated cylinders; a fueling rate; intake and exhaust cam phaser angles; a boost pressure; and an EGR valve opening area. The ECM  47  may control actuator values in order to cause the engine  46  to generate a desired engine output torque. 
     The powertrain system  40  may further include one or more devices and/or accessories  199  that engage with and/or provide a load on the engine  46 . The devices and/or accessories may include an air-conditioning system, compressor and/or clutch, an alternator, a generator, a cooling fan, etc. The ECM  47  may control operation of the device and/or accessories  199 . 
     The engine system  42  may further include any number of temperature and/or pressure sensors on the exhaust system  54  for detecting temperatures and/or pressures of exhaust gas, temperatures of the catalyst  136 , temperatures of the particulate filter  56 , and/or pressures in and out of the catalyst  136  and/or the particulate filter  56 . A temperature sensor  193  is shown for detecting a temperature T PF  of the particulate filter  56 . Pressure sensors  195 ,  197  are shown for detecting inlet and outlet pressures P 1  and P 2  of the particulate filter  56 . 
     Referring now also to  FIG. 3 , which shows a representative example portion  200  of the engine system  42  of  FIG. 1 , which may be referred to as a temperature control system. The temperature control system  200  includes the engine  46 , the temperature module  50 , the transmission  53 , and the turbine  160 - 1 . The engine  46  includes an engine block  202 , one or more cylinder heads (a single head  204  is shown), an intake manifold  206 , and an integrated exhaust manifold (IEM)  208 . The engine block  202 , cylinder heads, and the IEM  208  are cooled by a coolant circulating through channels of conduits of a coolant flow circuit  210  and between (i) a radiator  211  and (ii) the engine block  202 , the cylinder heads, and the IEM  208 . The engine block  202 , the cylinder heads, and the IEM  208  have respective coolant jackets (or coolant channels). The engine block  202  and transmission  53  may also be heated respectively via an engine oil heater (EOH)  212  and a transmission oil heater (TOH)  214 . Oil may be circulated between (i) the engine  46  and the transmission  53  and (ii) the oil heaters  212 ,  214 . 
     The temperature control system  200  may further include an electric pump  216 , a coolant control valve (CCV)  218 , a block valve  220 , a heater core  224 , a transmission valve  226 , a pump valve  228 , a core valve  230 , and a surge tank  232 . Although an electric pump  216  is shown, the electric pump  216  may be replaced with a manual pump that operates off of the engine  46 . The CCV  218  may include a first side and a second side having corresponding inputs and outputs. Coolant channels are provided (i) between an input of the second side of the CCV  218  and an output of the IEM  208 , an output of the head  204 , and an output of the block valve  220 , (ii) between an output of the second side of the CCV  218  and an input of the radiator  211 , (iii) between an output of the second side of the CCV  218  and an input of the electric pump  216 , and (iv) between an output of the first side of the CCV  218  and inputs of the EOH  212  and the TOH  214 . Coolant channels are also provided (i) between the output of the IEM  208  and an input of the first side of the CCV  218  and an input of the surge tank  232 , (ii) between an input of the heater core  224  and the outputs of the IEM  208 , the head  204 , and the block valve  220 , (iii) between an output of the electric pump  216  and an input of the pump valve  228 , and (iv) between an output of the pump valve  228  and an input of the intake manifold  206 . 
     Coolant channels are also provided (i) between an output of the heater core  224  and an input of the core valve  230 , (ii) between an output of the core valve  230  and outputs of the EOH  212  and the TOH  214 , and (iii) between the output of the core valve  230  and the input of the electric pump  216 . Coolant channels are also provided (i) between an output of the TOH  214  and the transmission valve  226 , and (ii) between an output of the transmission valve  226  and an input of the transmission  53 . Coolant channels are also provided (i) between an output of the turbine  160 - 1  and the output of the IEM  208 , the inputs of the first and second sides of the CCV  218 , and the input of the electric pump  216 , and (ii) between an input of the turbine  160 - 1  and the intake manifold  206 . The heater core  224  may be implemented as a heat exchanger and restricts flow of coolant. The coolant channel between the second side of the CCV  218  and the electric pump  216  is referred to as a bypass channel  250  that bypasses the radiator  211 . 
     During operation, coolant flows out of the electric pump  216 , may be restricted by the pump valve  228  and is provided to the intake manifold  206 . The coolant is passed from the intake manifold  206  to the heads, the engine block  202 , and an inlet  252  of the IEM  208 . During a startup period, the CCV  218  may be partially or fully closed and a significant portion of the coolant may be passed around the CCV  218  to the heater core  224 . During normal operation (i.e. periods of time outside of the cold startup period), coolant may be passed through the CCV  218  to the radiator  211 , the electric pump  216  and/or the EOH  212  and the TOH  214 . 
     The temperature control system  200  includes the temperature module  50 , which controls temperatures of the coolant entering and exiting the engine  46 . This includes temperatures of coolant entering and exiting the heads, the engine block  202  and the IEM  208 . This temperature control may be based on signals from various sensors and/or various parameters. As shown, the temperature control system  200  includes temperature sensors  260 ,  262 ,  264 ,  266 , which detect coolant temperatures of coolant out of the radiator T RAD , out of the engine block  202  T BLK , out of the head  204  T HEAD , and out of the IEM  208  T IEM . The sensors  260 ,  262 ,  264 ,  266  may be connected to respective ones of the conduits. The temperature module  50  controls operation of the electric pump  216  and the valves  228 ,  220 ,  226 ,  230  based on the signals and parameters (e.g., the temperatures T RAD , T BLK , T HEAD , T IEM ). 
     Referring now also to  FIG. 4 , which shows the temperature module  50 , which includes a startup module  300 , a fuel module  302 , a load module  304 , a flow rate module  306 , a first heat rejection module  308 , a second heat rejection module  310 , a mode module  312 , a pump module  314 , a valve module  316 , a CLT module  318 , an IEM module  320 , and a peak estimation module  322  (may be referred to as the “critical metal module”). The temperature module  50  may further include an off timer  326 , a start timer  328  and a memory  330 . The modules  50 ,  300 ,  302  may receive signals from various sensors, such as from the sensors  178 ,  184 ,  186 ,  192 ,  260 ,  262 ,  264 ,  266 . For further defined structure of the modules of  FIGS. 2-4  see below provided method of  FIG. 5  and below provided definition for the term “module”. 
     The memory  330  may store one or more tables  332  for each of the modules  50 ,  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 . As an alternative, the memory  330  may be external to the temperature module  50  and may be accessed by the temperature module  50 . The memory  330  may store maps, tables, algorithms, etc. used by the modules  50 ,  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 . As an example, the memory  330  may store tables for relating and determining parameters output from the modules  50 ,  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322  to input parameters received by the modules  50 ,  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 . These relationships are further described below. 
     The systems disclosed herein may be operated using numerous methods. An example method is illustrated in  FIG. 5 . In  FIG. 5 , a temperature control method is shown. Although the following tasks are primarily described with respect to the implementations of  FIGS. 2-4 , the tasks may be easily modified to apply to other implementations of the present disclosure. The tasks may be iteratively performed. Each of the following tasks may be performed by the temperature module  50  and/or by one or more of the modules  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 . 
     The method may begin at  400 . At  402 , the temperature module  50  receives signals from the sensors  178 ,  184 ,  186 ,  192 ,  260 ,  262 ,  264 ,  266  and/or other sensors (e.g., a vehicle speed sensor  348 ). The signals are indicative of an engine speed RPM ( 350 ), an intake air temperature IAT ( 352 ), a mass air flow MAF ( 354 ), a manifold absolute pressure MAP ( 356 ), a vehicle speed VSPD ( 349 ), a coolant intake manifold temperature T RAD  ( 358 ), a coolant engine temperature T ENG  ( 360 ), a coolant head temperature T HEAD  ( 362 ), and a coolant IEM temperature T IEM  ( 364 ). 
     At  404 , the startup module  300  determines whether a cold startup of the engine  46  is being performed by determining whether one or more of the temperatures T RAD , T BLK , T HEAD , T IEM  is less than respective predetermined temperatures and/or if the engine has been OFF for more than a predetermined period. The startup module  300  generates a first condition signal COND 1  ( 365 ) based on this determination. The OFF timer  324  indicates an amount of time the engine has been OFF. This allows the startup module  300  to determine whether a cold start is being performed. This determination may be performed based on (or in response to) a startup of the engine (e.g., fuel and ignition enabled), a key-ON start of the engine, a push-button start of the engine, etc. As an example, the startup module  300  may determine whether the head temperature T HEAD  is less than a predetermined temperature (e.g., 140° C., 120° C., 110° C., 100° C.). If a cold startup is being performed, task  406  is performed, otherwise the method may end at  430 , return to task  402 , or perform one or more of tasks  422 ,  424 ,  426 ,  428  as shown. 
     At  406 , the fuel module  302  may determine a total amount of fuel provided to the engine  46  since a last startup of the engine  46 . The total amount of fuel is an accumulation of the fuel provided to each of the cylinders since the last startup of the engine  46 . This determination may be performed based on a start time and/or an amount of time since the last startup. The start time and/or the amount of time since the last startup may be provided via the start timer  328 . The fuel module  302  determines whether the total amount of fuel is greater than a predetermined amount of fuel and generates a second condition signal COND 2  ( 366 ). If the second condition signal COND 2  is TRUE, task  408  may be performed, otherwise the method may end at  430 , return to task  402 , or perform one or more of tasks  422 ,  424 ,  426 ,  428  as shown. In one embodiment, task  406  is skipped and task  408  is performed after task  406 . 
     At  408 , the load module  304  determines whether a load on the engine  46  and/or the transmission  53  and/or an amount of torque output from the engine  46  and/or the transmission  53  are less than corresponding predetermined thresholds. The load module  304  may determine the load on the engine  46  and/or the transmission  53  and/or the amount of torque output from the engine  46  and/or the transmission  53  based on the signals RPM, IAT, MAF, MAP, VSPD, a pump control signal PUMPCTRL, and/or other signals and/or parameters that affect the load and/or torque values determined. The PUMPCTRL signal may be generated at, for example, task  410  to control the speed of the electric pump  216 . The load module  304  may determine an air per cylinder (APC) ( 367 ), which may be used to determine the load and/or torque values. The load module  304  generates a third condition signal COND 3  ( 368 ), which indicates whether the load on the engine  46  and/or the transmission  53  and/or the amount of torque output from the engine  46  and/or the transmission  53  are less than corresponding predetermined thresholds. If the third condition signal COND 3  is TRUE, one or more of tasks  410 ,  412 ,  414 ,  416  may be performed, otherwise the method may end at  430 , return to task  402 , or perform one or more of tasks  422 ,  424 ,  426 ,  428  as shown. 
     Based on the condition signals COND 1 , COND 2 , and COND 3 , the mode module  312  generates a mode signal MODE ( 368 ) indicating whether a cold startup process is being performed. For example, if each of the conditions COND 1 , COND 2 , COND 3 , is TRUE, the mode signal MODE may indicate a cold startup process is being performed. The mode signal MODE, may also be generated based on a critical metal temperature CMTemp ( 380 ), which is estimated by the peak estimation module  322  at  418 . Although the peak estimation module  322  is primarily described as estimating a temperature of a hottest metal location on the engine  46 , the peak estimation module  322  may determine a temperature of a hottest non-metal location on the engine  46 . Thus, the CMTemp may indicate a hottest non-metal temperature on the engine  46 . The mode module  312  may transition from operating in a cold startup mode during a cold startup period to operating in a post startup mode at the end of the cold startup period. This may occur when the critical metal temperature CMTemp is greater than a predetermined critical metal (or non-metal) temperature. The critical metal temperature CMTemp may refer to a temperature of a hottest point on the engine  46 , such as a point on the head  204 , a point between the head  204  and the IEM  208 , a point on an exhaust bridge on the head  204 , a point on the IEM  208 , or some other point on the engine  46 . 
     At  410 , the pump module  314  based on the mode signal MODE generates the pump control signal PUMPCTRL ( 369 ) to operate the pump  216  at a predetermined speed to circulate coolant. The predetermined speed may be a minimum operating speed of the pump. As an example, the pump  216  may have an operating range of 300-6000 revolutions per minute (RPM). The predetermined speed may be 300 RPM or a speed less than 400 RPM. 
     At  412 , the valve module  316 , based on the mode signal MODE, may partially or fully close the CCV  218 . If operating in the cold startup mode, the CCV  218  may be partially or fully closed. In one embodiment, the CCV  218  is fully closed. This aids in restricting flow of the coolant and diverts a large portion of the coolant to the heater core  224 , which also restricts the flow of the coolant. This minimizes coolant flow to the radiator  211  and to the bypass  250 . A first valve signal V 1  ( 370 ) is generated to control the position of the CCV  218 . The position of the CCV  218  may be based on the mode signal MODE, one or more of the temperatures T RAD , T BLK , T READ , T IEM , a flow rate FLWRT ( 371 ) of the coolant as determined at  418 , and/or one or more of the other parameters determined by the modules  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 , as disclosed herein. 
     At  414 , the valve module  316 , based on the mode signal MODE, may partially close the pump valve  228  to further restrict flow of the coolant. If operating in the cold startup mode, the pump valve  228  may be partially closed or left fully open. In one embodiment, the pump valve  228  is left fully open. A second valve signal V 2  ( 372 ) is generated to control the position of the pump valve  228 . The position of the pump valve  228  may be based on the mode signal MODE, one or more of the temperatures T RAD , T BLK , T HEAD , T IEM , the flow rate FLWRT, and/or one or more of the other parameters determined by the modules  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 , as disclosed herein. At  416 , the valve module  316 , based on the mode signal MODE, may partially or fully close the block valve  220 . If operating in the cold startup mode, the block valve  220  may be partially or fully closed. In one embodiment, the block valve  220  is fully closed. A third valve signal V 3  ( 373 ) is generated to control the position of the block valve  220 . The position of the block valve  220  may be based on the mode signal MODE, one or more of the temperatures T RAD , T BLK , T HEAD , T IEM , the flow rate FLWRT, and/or one or more of the other parameters determined by the modules  300 ,  302 ,  304 ,  306 ,  308 ,  310 ,  312 ,  314 ,  316 ,  318 ,  320 ,  322 , as disclosed herein. 
     Tasks  410 ,  412 ,  414 ,  416  may be performed to restrict coolant flow and provide a flow rate that is less than a predetermined flow rate to maximize and/or maintain a predetermined level of fuel efficiency. The restriction allows thermal energy to be transferred to quickly heat up the head  204  and the IEM  208 .  FIG. 6  shows a pressure versus engine coolant flow rate plot that includes (i) pressure versus engine coolant flow rate curves  415  for different engine loads, and (ii) pressure versus engine coolant flow rate curves  417  for different amounts of coolant flow restriction. A dashed box  419  indicates an area of the plot and a corresponding operating range in which fuel efficiency is maximized due to low engine coolant flow rates. The temperature module  50  may operate in this range during the cold startup period. 
     At  418 , the critical metal temperature CMTemp is estimated. The flow module  306  determines the flow rate FLWRT based on a speed of the pump  216 , positions of one or more of the valves  218 ,  220 ,  226 ,  230 . The speed of the pump  216  may be indicated by the pump control signal PUMPCTRL. One of the tables  332  may relate flow rates to speeds of the pump  216  and positions of the valves,  218 ,  220 ,  226 ,  230 . 
     The first heat rejection module  308  estimates an amount of heat rejection QENG ( 375 ) of the engine  46  based on the temperatures T RAD , T BLK . The amount of heat rejection QENG may be determined based on equation 1, where {dot over (Q)} is replaced with QENG, {dot over (m)} is the coolant flow rate FLWRT of the engine  46  (or engine block  202 ), c is a heat constant, and Δt is a difference in temperature across the engine  46 . The difference in temperature Δt may be determined based on and/or a difference between the temperatures T RAD , T BLK . The heat rejection energy QENG is a function of torque output of the engine  46  and the speed RPM of the engine  46 .
 
 {dot over (Q)}={dot over (m)}cΔt   (1)
 
     The second heat rejection module  310  estimates an amount of heat rejection QIEM ( 377 ) of the IEM  208  based on the temperatures T RAD , T IEM . The amount of heat rejection QIEM may be determined based on equation 1, where {dot over (Q)} is replaced with QIEM, {dot over (m)} is the coolant flow rate FLWRT of the engine  46  (or IEM  208 ), and Δt is a difference in temperature across the IEM  208 . The difference in temperature Δt may be determined based on and/or a difference between the temperatures T RAD , T IEM . The heat rejection energy QENG is a function of torque output of the engine  46  and the speed RPM of the engine  46 . 
     The coolant module  318  estimates a temperature of the coolant CLTemp ( 379 ) based on the detected temperature T HEAD , the flow rate FLWRT, and the amount of heat rejection QENG. The temperature of the coolant CLTemp may be an actual coolant temperature in the head  204 . As with the other parameters determined during this method, the temperature of the coolant CLTemp may be determined using a corresponding table. The table for CLTemp may relate actual temperatures of the coolant through the head  204  to detected temperatures provided via the sensor  264 , coolant flow rates, and amounts of heat rejection of the engine  46 . The detected temperature provided by the sensor  264  is a delayed temperature for the actual temperature of the coolant in the head  204 . Thus, the estimate of the temperature of the coolant CLTemp may be referred to as a delayed estimate. The amount of delay is based on the coolant flow rate FLWRT. 
     The IEM module  320  estimates a temperature of the IEM  208  (or a temperature of the coolant passing through the IEM  208 ) IEMTemp ( 381 ) based on the temperature T IEM , the flow rate FLWRT and the amount of heat rejection of the IEM  208 . The temperature of the IEM  208  IEMTemp may be determined using a corresponding table. The table for IEMTemp may relate actual temperatures of the IEM  208  to detected temperatures of the IEM  208  detected by the sensor  266 , coolant flow rates and amounts of heat rejection of the IEM  208 . The detected temperature provided by the sensor  266  is a delayed temperature for the actual temperature of the IEM  208 . Thus, the estimate of the temperature of the IEM  208  IEMTemp may be referred to as a delayed estimate. The amount of delay is based on the coolant flow rate FLWRT. 
     The peak estimation module  322  estimates the critical metal temperature CMTemp based on the air per cylinder APC, the engine speed RPM, the coolant temperature CLTemp, and the temperature of the IEM  208  IEMTemp. The critical metal temperature CMTemp may be determined using a corresponding table relating critical metal temperatures to APCs, RPMs, coolant temperatures, and IEM temperatures. 
     At  420 , the mode module  312  determines whether to transition from the cold startup mode to the post cold startup mode based on the critical metal temperature CMTemp. If the critical metal temperature CMTemp is greater than or equal to the predetermined critical metal (or non-metal) temperature, one or more of tasks  422 ,  424 ,  426 ,  428  may be performed. If the critical metal temperature CMTemp is less than the predetermined critical metal (or non-metal) temperature, task  408  may be performed. 
     At  422 , pump module  314 , based on the mode signal MODE may increase the speed of the pump  216  and/or operate the pump  216  within a normal operating window. The normal operating window may include pump speeds greater than the pump speeds implemented during the cold startup mode. 
     At  424 , the valve module  316  may partially or fully open the CCV  218 . The valve module  316  may change the position of the CCV  218  to be in a less restrictive position than the position implemented during the cold startup mode. At  426 , the valve module  316  may increase an opening of and/or fully open the pump valve  228 . The valve module  316  may change the position of the pump valve  228  to be in a less restrictive position than the position implemented during the cold startup mode. At  428 , the valve module  316  may partially or fully open the block valve  220 . The valve module  316  may change the position of the block valve  220  to be in a less restrictive position than the position implemented during the cold startup mode. Subsequent to tasks  422 ,  424 ,  426 ,  428 , the method may end as shown at  430  or return to task  402 . 
     The above-described tasks are meant to be illustrative examples; the tasks may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the tasks may not be performed or skipped depending on the implementation and/or sequence of events. For example, tasks  404 ,  406 , and  408  may be performed in a different order. As another example, tasks  404  or  406  may be performed instead of task  408  if the critical metal temperature is greater than or equal to the predetermined critical metal (or non-metal) temperature at task  420 . 
     The above-described examples include operating a pump and/or positioning one or more valves to provide a low coolant flow rate during a cold startup period of an engine. Slowly moving coolant away from engine hot spots (areas of the engine that are hotter than adjacent areas of the engine) during warm-up improves engine warm-up robustness without impacting fuel efficiency. The disclosed examples use time delayed coolant sensor feedback while providing the low coolant flow rate to assist in estimating and/or predicting temperatures of a critical metal point on the engine. The disclosed example may reduce calibration time of a temperature control system. The utilized feedback information may reduce erosion of metal of an engine previously associated with coolant boiling in traditional systems. 
     The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure. 
     Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” 
     In this application, including the definitions below, the term “module” or the term “controller” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip. 
     The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module. 
     The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules. 
     The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc). 
     The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer. 
     The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc. 
     The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language) or XML (extensible markup language), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective C, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5, Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, and Python®. 
     None of the elements recited in the claims are intended to be a means-plus-function element within the meaning of 35 U.S.C. § 112(f) unless an element is expressly recited using the phrase “means for,” or in the case of a method claim using the phrases “operation for” or “step for.”