METHOD FOR MONITORING A COOLING SYSTEM

Abstract

Method for a cooling system (100), comprising: Adjusting a coolant flow with a thermostat (145) based on the thermostat position, estimating a coolant temperature (T RO ) at a position between one end of a radiator block (153) and a connection point (150) between a lower hose (143) of a radiator (141) and a heater core output line (151); and Specify a cooling system condition based on the estimated coolant temperature (T RO ), wherein the cooling system condition includes a malfunction of the radiator (141), a radiator life, and a thermostat degeneration.

Description

Area

[0001] The present description generally relates to methods for monitoring a cooling system condition based on an estimated coolant temperature at a location between an end of a radiator core and a junction between a lower hose of a radiator and a heater core output line. Background / Brief description

[0002] In automotive thermal management, the coolant temperature in a cooling system is tightly controlled for improved engine efficiency and emissions. The cooling system may include a radiator as a main heat exchanger and a thermostat to control the coolant flow through the radiator. For example, at one thermostat position, the coolant flow may bypass the radiator so that waste heat can be used to warm up the engine. At another thermostat position, the coolant flow may flow through the radiator for maximum heat dissipation. Cooling system deterioration, such as thermostat degradation, can worsen engine fuel consumption and emissions.

[0003] Other approaches to monitoring the cooling system involve comparing an estimated engine coolant temperature with a measured engine coolant temperature. An exemplary concept is shown by Davison et al. in US patent US 6,302,065 B1. There, the engine coolant temperature is estimated using a coolant temperature model. Based on the position of a thermostat, a high coolant temperature model or a low coolant temperature model is used to estimate the engine coolant temperature. Degradation of the coolant temperature sensor and thermostat can be determined if the difference between the estimated and measured engine coolant temperatures is greater than a threshold.

[0004] Further methods for monitoring the cooling system condition are known from the documents DE 10 2013 205 229 A1, DE 103 92 219 T5 and DE 600 03 901 T2, wherein the said DE 10 2013 205 229 A1 proposes individually closing and opening valves of the cooling system and detecting corresponding changes in the coolant temperature by means of several temperature sensors.

[0005] However, the inventors of the present invention have recognized potential problems with such methods. As one example, the coolant temperature in the cooling system fluctuates in response to the position of the thermostat. The fluctuation in coolant temperature can cause system degeneration. For example, the fluctuation in coolant temperature in the radiator can cause expansion and contraction of various areas of the radiator and can lead to radiator malfunction, such as leakage. In addition to coolant leakage, radiator malfunction can cause engine overheating and severe damage to the vehicle system. In addition, when hot engine coolant is introduced into the cold coolant mass in the radiator, stagnant flow bulges are formed due to the viscosity differences between the hot and cold coolant.Radiator malfunctions due to thermal stress and fatigue are more likely to occur near areas of high temperature variation caused by either flow congestion or interrupted flow.

[0006] The present invention is based on the object of providing an improved method for a cooling system that avoids disadvantages of the prior art and advantageously develops them further. In particular, improved monitoring of the cooling system status is to be achieved.

[0007] According to the invention, the stated object is achieved by a method according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0008] The method thus includes: adjusting a coolant flow with a thermostat; based on the thermostat position, estimating a coolant temperature at a location between an end of a radiator core and a junction between a lower hose of a radiator and a heater core outlet line; and indicating a cooling system condition based on the estimated coolant temperature, wherein the cooling system condition includes radiator malfunction, radiator usage time, and thermostat degradation. In this way, the cooling system condition can be assessed before system degradation occurs, so that measures can be taken to prevent future system malfunction.

[0009] The method may determine radiator malfunction and thermostat degeneration based on an estimated coolant temperature at the radiator outlet. The radiator outlet is defined as an opening on the radiator shell to which a lower hose is coupled. The coolant temperature may be estimated as a mathematical function of a coolant flow rate at the radiator outlet. The direction of coolant flow at the radiator outlet depends on the thermostat position. The thermostat may be in a first position to block low-temperature coolant from the thermostat to the radiator and in a second position to allow high-temperature coolant from the thermostat to the radiator. A coolant pump in fluid communication with the radiator outlet may pump coolant to an engine block.In radiator bypass mode, when no coolant flows from the thermostat to the radiator inlet, operating the coolant pump can create a low-pressure condition extending from the pump inlet to the radiator outlet. This low-pressure condition can draw hot coolant from the heater core through a radiator vent line to the radiator outlet. Consequently, the coolant temperature at the radiator outlet can be affected by the reversed hot coolant flow drawn by the heater core. By incorporating the reverse coolant flow into a model, the coolant temperature fluctuation in the cooling system can be accurately simulated. The model can further be used to estimate other engine operating parameters, such as engine temperature and radiator temperature, for improved engine control. By evaluating the estimated coolant temperature fluctuation, radiator malfunction can be predicted in real time without the need for additional hardware.Thermostat degeneration can also be determined by comparing the estimated coolant temperature with a coolant temperature measured at the radiator outlet.

[0010] It should be understood that the foregoing summary is provided to introduce, in a simplified manner, a selection of concepts that are further described in the detailed description. Furthermore, the claimed subject matter is not limited to implementations that resolve any disadvantages noted above or in any part of this disclosure. Brief description of the drawings Fig. 1A schematically shows an exemplary embodiment of a cooling system for an engine with a thermostat at a first position. Fig. 1B shows the cooling system with the thermostat in a second position. Fig.2 shows a schematic diagram of an exemplary cylinder of a multi-cylinder engine with an emissions control device coupled to an engine exhaust system. Fig. 3 shows an exemplary method for monitoring a cooling system. Fig. 4 shows an exemplary method for operating an engine based on a thermal runaway prediction model. Fig. 5 are timelines illustrating various engine parameters while the exemplary method is implemented. Detailed description

[0011] The following description relates to systems and methods for monitoring a cooling system of an internal combustion engine, such as that described in Fig. 1A and Fig.1B. The cooling system includes a thermostat for controlling coolant flow in response to engine coolant temperature. For example, when the engine coolant temperature is high, coolant may flow through the radiator for heat dissipation, as shown in Fig. 1A. When the engine coolant temperature is low, the coolant can bypass the radiator to warm up the engine, as shown in Fig. 1B is shown. Fig. 2 shows an exemplary internal combustion engine system coupled to the cooling system. Fig.3 is a flowchart of an exemplary method for monitoring the cooling system based on a thermal instability prediction model. The model can predict radiator malfunction and thermostat degradation based on an estimate of the coolant temperature at a location between an end of a radiator core and a junction between a lower radiator hose and a heater core output line. Fig. Figure 4 shows that the thermal instability prediction model can be integrated into a thermal state estimation function and can generate virtual temperature signals to simplify engine operation. Fig. Figure 5 illustrates the status of the engine operating parameters and actuators during the implementation of the exemplary method.

[0012] Returning to Fig.1, an exemplary cooling system 100 of a vehicle is set forth. The cooling system may be coupled to an engine 10 and circulate coolant through the engine. An engine-driven coolant pump 146 may be coupled directly upstream of the engine 10 to supply coolant through passages in the engine block, head, etc., to absorb engine heat. The coolant pump 146 may alternatively be an electric pump. Heated coolant from the engine outlet may be directed to a heater core 140, from where the heat may be transferred to a passenger compartment. The heated coolant may flow from the thermostat via an upper hose 147 to a radiator 141. The radiator 141 may include a front tank 154 directly coupled to the upper hose 147, an end tank directly coupled to a lower hose 143, and a radiator core 153 positioned between the front tank and the end tank.Fin honeycombs may be arranged within the radiator core to release coolant heat into the ambient air. The radiator 141 may be coupled to a radiator fan 148 to provide cooling airflow support through the radiator. The radiator fan speed may be controlled by an actuator 94.

[0013] Cooled coolant is drawn to the engine via the lower hose 143 by operating the pump 146. A vent hose 140E may be coupled between the radiator end tank 142 and the coolant pump 146 to vent excess air from the radiator. In one embodiment, a coolant reservoir (not shown) may be positioned upstream of the pump inlet, and the vent flow of excess air from the radiator may first be directed through the coolant reservoir before being supplied to the pump 146.

[0014] A temperature sensor 149 may be used to monitor the coolant temperature. In one embodiment, the temperature sensor 149 may be positioned within the end tank 142. In another embodiment, the temperature sensor 149 may be coupled to the lower hose 143. In another embodiment, the temperature sensor 149 may be positioned at the radiator outlet. The radiator outlet is an opening on the radiator shell that is directly coupled to the lower hose 143. In yet another embodiment, no temperature sensor may be coupled to the lower hose or the radiator outlet. Instead, the temperature sensor may be positioned elsewhere in the engine system, such as coupled to an engine block or a cylinder head. In this embodiment, a temperature sensor may be included at at least one location in the engine system.For example, the temperature sensor can be coupled to the engine block or the cylinder head.

[0015] A thermostat 145 may be disposed in direct fluid communication downstream of the engine 10. In one embodiment, the thermostat 145 may be a wax thermostat. In response to the coolant temperature, the position of the thermostat may be continuously adjusted between a first position where coolant flows through the radiator and a second position where coolant bypasses the radiator. The thermostat position may be measured with a sensor 152.

[0016] When the thermostat 145 is in a first position as shown in Fig.1A, a portion of the coolant exiting the engine 10 is directed to the heater core 140. The remainder of the coolant exiting the engine 10 is directed to the radiator via the upper hose 147. No coolant flow occurs in the passage 144. The coolant exits the radiator end tank 142 via the radiator outlet and combines with coolant from the heater core 140 at a junction 150 between the lower hose 143 and a heater core outlet line 151. The mixed coolant is then pumped through the engine 10 by the pump 146. Excess air and some coolant may flow from the radiator end tank to the coolant pump through the vent hose 140E.

[0017] When the thermostat 145 is in a second position as shown in Fig.1B, the coolant flow to the radiator 141 is blocked. In other words, the coolant flow in the upper hose 147 is zero. Coolant exiting the engine 10 first flows through the heater core 140 and the passage 144 and is then reunited at a location upstream of the inlet of the pump 146. While coolant is being pumped into the engine 10 by the pump 146, a low-pressure condition may exist at the pump inlet side and propagate back to the lower hose 143 and the radiator end tank 142. Thus, a pressure differential may exist between the outlet of the heater core 140 and the radiator outlet (or radiator end tank). The pressure differential may draw coolant exiting the heater core via the heater core outlet line 151 and the vent hose 140E to the radiator end tank. This coolant flow may displace coolant from the end tank 142, forcing a small flow out of the lower hose 143.The temperature of the coolant entering the end tank 142 from the heater core 140 may be higher than the coolant temperature in the end tank 142. Thus, the coolant temperature at the radiator outlet may increase due to the reverse coolant flow in the vent hose 140E when the radiator is bypassed.

[0018] Fig.1A-1B illustrate example configurations with relative positioning of the various components. If they are shown as directly touching or directly connected to one another, then such elements may be referred to as directly touching or directly connected, respectively, in at least one example. Similarly, elements shown contiguous or adjacent may be contiguous or adjacent, respectively, in at least one example. As another example, elements arranged separately from one another, with only a blank space between them and no other components, may be so referred to in at least one example.

[0019] Returning to Fig.2 is a schematic diagram showing one cylinder of a multi-cylinder engine 10, which may be included in a propulsion system of a motor vehicle. The engine 10 may be controlled at least in part by a control system, including a controller 12, and by input from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a pedal position proportional signal PP. A combustion chamber (i.e., a cylinder) 30 of the engine 10 may include combustion chamber walls 32 with a piston 36 positioned therein. The piston 36 may be coupled to a crankshaft 40 such that reciprocating motion of the piston is translated into rotational motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate gearing system.Furthermore, a starter can be coupled to the crankshaft 40 via a flywheel in order to start operation of the engine 10.

[0020] Combustion chamber 30 may receive intake air via an intake passage 42 from an intake manifold 46 and may expel exhaust gases via an exhaust passage 48. Intake manifold 46 and exhaust passage 48 may selectively communicate with combustion chamber 30 via a respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may include two or more intake valves and / or two or more exhaust valves.

[0021] A fuel injector 66 is shown coupled directly to the combustion chamber 30 for injecting fuel directly therein in proportion to the pulse width of the FPW signal received from the controller 12 via an electronic driver 68. Thus, the fuel injector 66 provides what is known as direct injection of fuel into the combustion chamber 30. The fuel injector may be mounted, for example, in the side of the combustion chamber or in the top of the combustion chamber. Fuel is supplied to the fuel injector 66 by a fuel system 2.

[0022] The fuel injection timing from the fuel injector (or injectors) can be adjusted depending on the engine operating conditions. For example, the fuel injection timing can be retarded or advanced from values ​​preset by the controller to maintain the desired engine torque and power.

[0023] The intake manifold 42 may include a throttle 62 with a throttle valve 64. The position of the throttle valve 64 may be varied by the controller 12 via a signal provided to an electric motor or actuator included in the throttle 62, a configuration generally referred to as electronic throttle control (ETC). In this manner, the throttle 62 may be actuated to vary the intake air provided to the combustion chamber 30, among other engine cylinders. The position of the throttle valve 64 may be provided to the controller 12 by the throttle position signal TP. The intake manifold 42 may include a mass air flow sensor 120 and a manifold air pressure sensor 122 for providing the respective MAF and MAP signals to the controller 12.

[0024] The combustion chamber 30 or one or more other combustion chambers of the engine 10 may be operated in a compression ignition mode without an ignition spark. Furthermore, the engine 10 may be boosted by a compressor 162 disposed along the intake manifold 46 and a turbine 164 disposed along the exhaust passage 48 upstream of the exhaust aftertreatment system 70. Even if Fig. 2 shows only one cylinder of a multi-cylinder engine, each cylinder may equally include its own set of intake / exhaust valves, fuel injection, etc.

[0025] An exhaust gas sensor 126 is shown coupled to the exhaust passage 48 upstream of an exhaust aftertreatment system 70. The sensor 126 may be any suitable sensor for providing an indication of an exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a dual-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor.

[0026] The exhaust aftertreatment system 70 may include a plurality of emission control devices, each of which may perform an exothermic reaction when excess oxygen is present in the exhaust gas during selected conditions (e.g., selected temperatures). For example, the exhaust aftertreatment system 70 may include a diesel oxidation catalyst (DOC) 80 disposed along the exhaust passage 48 downstream of the turbine 164. The diesel oxidation catalyst may be configured to oxidize HC and CO in the exhaust gas. A selective catalytic reduction (SCR) catalyst 82 may be disposed along the exhaust conduit downstream of the DOC 80. The SCR catalyst may be configured to reduce NOx in the exhaust gas to nitrogen and water.A urea atomizer 84 (or any suitable SCR reductant source, such as an ammonium source) may be disposed upstream of the SCR catalyst 82 and downstream of the DOC 80. A diesel particulate filter (DPF) 86 may be disposed along the exhaust conduit downstream of the SCR catalyst 82. The DPF may be configured to remove diesel particulate matter (or soot) from the exhaust gas.

[0027] The control 12 is in Fig.2 as a microcomputer having a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, shown as a read-only memory chip 106 in this particular example, a random access memory 108, a life support memory 110, and a data bus.The controller 12 may receive various signals from sensors coupled to the engine 10 in addition to the signals discussed above, including the induced mass air flow (MAF) measurement from a mass air flow sensor 120; the engine coolant temperature (ECT) from the temperature sensor 112 coupled to a cooling sleeve 114; a profile ignition pickup (PIP) signal from a Hall effect sensor 118 (or other type) coupled to the crankshaft 40; the throttle position (TP) from a throttle position sensor; the boost pressure from a boost pressure sensor 123; and an absolute manifold pressure (MAP) signal from a sensor 122. An engine speed signal, RPM, may be generated by the controller 12 from the PIP signal. The manifold pressure signal MAP from a manifold pressure sensor can be used to provide an indication of vacuum or pressure in the intake manifold.Additionally, the controller 12 may communicate with a cluster display device 140A to, for example, warn the driver of defects in the engine or exhaust aftertreatment system.

[0028] Furthermore, the controller 12 may communicate with various actuators, including engine actuators such as fuel injectors, an electronically controlled intake air throttle, camshafts, etc. In some examples, a storage medium of a read-only memory chip 106 may be programmed with computer-readable data representing instructions executable by the microprocessor unit 102 for performing the methods described below, as well as other variations anticipated but not expressly listed.

[0029] Based on the signals received from the various sensors of the Fig. 1 and Fig.2 and instructions stored in the controller's memory, the controller can control 12 different actuators of the Fig. 1 and Fig. 2 to adjust engine operation. As an example, adjusting the coolant temperature may include adjusting an actuator 94 of the cooling fan 148 to adjust the cooling airflow through the radiator.

[0030] Fig. 3 shows an exemplary method 300 for monitoring the cooling system condition. The method estimates the coolant temperature at a location between one end of a radiator core (such as 155 in Fig. 1) and a connection point between a lower hose of the radiator and a heater core output line (such as the connection point 150 in Fig. 1) based on a thermal instability prediction model. Within the model, the coolant flow rate in the lower hose of the radiator (such as the lower hose 143 in Fig.1) in response to a thermostat position. When the thermostat is in a first position where the coolant flows through the radiator (as in Fig. 1A), the coolant flow rate in the lower hose of the radiator may be a function of the coolant flow rate through the engine and the coolant flow rate through a heater core. When the thermostat is in a second position where the coolant bypasses the radiator (as shown in Fig.1B), the coolant flow rate in the lower hose of the radiator may be a function of the coolant flow rate through the engine. In other words, in radiator bypass mode, even when no coolant is flowing from the engine to the radiator, the coolant flow rate in the vent hose may be non-zero due to the lower pressure at the radiator outlet compared to the heater core outlet. By calculating the amplitude and / or the number of cycles of the coolant temperature fluctuation at the radiator outlet, a radiator malfunction may be predicted. By comparing the estimated coolant temperature with a measured coolant temperature, thermostat or radiator degradation may be determined.

[0031] Instructions for performing method 300 and the other methods included herein may be executed by a controller (such as controller 12 in Fig.2) based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to the Fig. 1 and Fig. 2. The controller may use motor actuators of the motor system to adjust motor operation according to the methods described below.

[0032] In step 301, the controller estimates the vehicle operating conditions. The controller obtains measurements from various sensors in the engine system and estimates the operating conditions, including engine load, vehicle speed, engine rpm, engine coolant temperature, thermostat position, vehicle cabin temperature, and ambient temperature.

[0033] At step 302, method 300 estimates the coolant temperature T ROat a position between one end of a radiator core and a junction between a radiator lower hose and a heater core outlet pipe. As an example, the controller may measure the coolant temperature T RO at a radiator outlet, wherein the radiator outlet is an opening in the radiator shell and is directly coupled to a lower hose. As another example, the controller may estimate the coolant temperature T RO in the radiator tank. In yet another example, the control system can estimate the coolant temperature T RO in the lower radiator hose. As a non-limiting example, the coolant temperature T RO hereinafter referred to as coolant temperature at the radiator outlet.

[0034] The coolant temperature T ROis estimated using a thermal instability model in which coolant flow is developed based on the thermostat position. In other words, the estimated coolant temperature is a mathematical function of the thermostat position. The thermal instability model can predict delays that affect thermostat positions and coolant temperature fluctuations, such as coolant temperature fluctuations at the radiator outlet. For example, inputs to the thermal instability model can include vehicle speed, engine speed, vehicle cabin temperature, and ambient temperature, which are measured or estimated at step 302. Outputs of the thermal instability model can include estimates of the radiator outlet temperature, engine temperature, and radiator temperature. The thermostat position can also be estimated rather than measured based on the inputs listed above.The thermal instability model can be created based on equations 1-16: CengdTengdt=Qcomb−keng(Teng−Tamb)+wengccool(Teng,in−Teng) CraddTraddt=−krad(Trad−Tamb)+wradccool(Teng−Trad) CROdTROdt=wradccool(Trad−TRO)+wmixccool(Teng,in−TRO) CHCdTHCdt=−kHC(THC−Tcab)+wHCccool(Teng−THC) weng=aeng,w1N+aeng,w2NuTstat wHC=aHC,w1N wRAD=(weng−wHC)uTstat wBP=(weng−wHC)(1−uTstat) wmix=amix,w1Weng(1−uTstat) wRO=wRAD+wmix wair=aair,w1vveh none=aeng,k1weng+aeng,k2 kHC=aHC,k1wHC2+aHC,k2wHC krad=arad,k1wair2+arad,k2wair uTstat[t]=Teng[t−TD,2]Ktstat(lift gain) Teng,in=wBPTeng+wHCTHC+wROTROwBP+wHC+wRO

[0035] The definition, source, and range / unit of the variables in Equations 1-16 are shown in TABLE 1. TABLE 1 variable Description source Area / Units C eng Thermal mass of the engine Calibration constant 1000-500000 J / K C rad Thermal mass of the cooler Calibration constant 1000-500000 J / K C RO Thermal mass of the radiator outlet Calibration constant 100-100000 J / K C HC Thermal mass of the heater core Calibration constant 100-100000 J / K T eng Engine temperature Internal variable °C T rad Radiator temperature Internal variable °C T RO Radiator outlet temperature Internal variable °C T HC Heating core temperature Internal variable °C T amb Ambient temperature External input °C T cab Vehicle cabin temperature External input °C T eng,in Engine intake temperature Internal variable °C c cool Specific heat of the coolant Calibration constant 2000-4000 J / kg-K w eng Engine coolant flow rate Internal variable kg / s w HC Coolant flow rate heater core Internal variable kg / s w RAD Coolant flow rate radiator Internal variable kg / s w BP Bypass coolant flow rate Internal variable kg / s w mix Coolant flow rate vent hose Internal variable kg / s w RO Coolant flow rateRadiator outlet Internal variable kg / s w air Air flow rate cooler Internal variable kg / s v veh Vehicle speed External input mph N Engine speed External input rpm u Tstat Thermostat position Internal variable (no unit)(normalized) a eng,w1 Motor flow constant Calibration constant 0.0001-0.01kg / srpm a eng,w2 Motor flow constant Calibration constant 0-0.01kg / srpm a HC,W1 Flow constant heater core Calibration constant 0-0.001kg / srpm a mix,w1 Flow constant vent hose Calibration constant 0.001-0.05 (without unit) a air,w1 Air flow constant cooler Calibration constant 0.005-0.3kg / srpm k eng Heat transfer coefficient engine Internal variable W / C k HC Heat transfer coefficient heating core Internal variable W / C k rad Heat transfer coefficient cooler Internal variable W / C a eng,k1 Heat transfer constant engine Calibration constant 0-1000 J / kg-K a eng,k2 Heat transfer constant engine Calibration constant 0-5000 W / K a HC,k1 Heat transfer constant heating core Calibration constant -5000-0 W-s 2 / kg 2 -K a HC,k2 Heat transfer constant heating core Calibration constant 500-1000 J / kg-K a rad,k1 Heat transfer constant cooler Calibration constant - 1000-0 W-s 2 / kg 2 -K a rad,k2 Heat transfer constant cooler Calibration constant 500-1000 J / kg-K t Time Internal variable Sec T D,2 Thermostat delay Calibration constant 0-20 sec K tstat(lift gain) Thermostat stroke curve Calibration table (function of temperature) 0-1 (no unit)(normalized)

[0036] Equations 5-14 are approximations and can be implemented using lookup tables. When the thermostat is in the first position (as in Fig. 1A), coolant flows through the radiator, and u Tstat = 1. The vent flow through the vent hose is in the direction that leaves the radiator. Since the vent flow is small, it can be neglected (zero). The coolant flow in passage 144 is zero. When the thermostat is in the second position (as in Fig. 1B), the coolant bypasses the radiator, and Tstat= 0. The radiator flow is zero, while the coolant flow from the vent hose is non-zero. When the coolant flow to the radiator is stopped, the operation of the coolant pump creates a pressure difference between the coolant pump inlet and the heater core outlet. This reverses the vent flow and flows into the radiator outlet, causing a heating effect.

[0037] Based on the estimated coolant temperature at the radiator outlet T OR The controller may determine whether to diagnose the status of the radiator at step 303 and / or the status of the thermostat at step 310. The status of the thermostat can only be diagnosed if a temperature sensor is available to measure the coolant temperature at the radiator outlet. Furthermore, the processes for diagnosing the radiator and the thermostat (steps 303 and 310) may run in parallel.

[0038] If it is determined that the status of the radiator is being diagnosed, the controller calculates the amplitude of the changes in the estimated coolant temperature from step 302 in step 304. For example, an average of the estimated coolant temperature may be determined. The average may be calculated using the running average of the coolant temperature. Alternatively, the average may be calculated by filtering the coolant temperature with a low-pass filter. The amplitude of the fluctuation in the estimated coolant temperature may then be determined by calculating the maximum difference between the current coolant temperature estimate and the calculated average.

[0039] At step 305, the amplitude of the coolant temperature fluctuation is compared to a predetermined threshold. If the amplitude is greater than a threshold, method 300 proceeds to step 307. Otherwise, if the amplitude is not greater than the threshold, method 300 proceeds to step 306, where the engine maintains the current engine condition.

[0040] In step 307, the controller increments the life cycle counter. The life cycle counter may be stored in the controller's memory. If the counter is greater than a predetermined threshold in step 308, the controller alerts a vehicle operator to a potential radiator malfunction in step 309. For example, the controller may illuminate a light on an indicator panel of the vehicle. Further, the controller may adjust engine operation in response to the potential radiator malfunction. For example, the controller may reduce the upper limit of the engine speed or engine load to prevent engine overheating.

[0041] At step 310, the controller may determine to diagnose the status of the thermostat if a temperature sensor is available to measure the coolant temperature at a location between an end of a radiator core and a junction between a radiator lower hose and a heater core output line. As one example, the temperature sensor may be located at a radiator outlet, where the radiator outlet is an opening in the radiator shell and is directly coupled to a lower hose. As another example, the temperature sensor may be coupled to the radiator end tank. As yet another example, the temperature sensor may be coupled to the radiator lower hose.

[0042] At step 311, the controller may determine the actual coolant temperature at the radiator outlet T RO ' from the temperature sensor.

[0043] At step 312, the estimated coolant temperature from step 302 is compared to the measured coolant temperature from step 311. As an example, the maximum magnitude of the fluctuation for each of the estimated and measured coolant temperatures is compared. Note that the estimated and measured coolant temperatures cannot simply be directly subtracted from each other because the phase of the estimated and measured fluctuations do not always match. However, the magnitudes of the fluctuations should roughly match. If the difference between the estimated and measured coolant temperatures is within a predetermined threshold, method 300 proceeds to step 306, where the engine maintains current operation. Otherwise, if the difference is greater than the threshold, method 300 may alert the vehicle operator of thermostat degeneration at step 313.Method 300 may also indicate radiator heat transfer degradation due to flow restrictions on either the air or coolant side of the radiator. As one example, an indicator may illuminate on a vehicle indicator panel. Further, in step 313, control may adjust engine operation in response to the thermostat degradation. For example, control may increase the speed of the radiator fan to reduce the coolant temperature. As another example, control may limit engine speed and / or engine load to prevent engine overheating.

[0044] Fig. 4 shows an exemplary method 400 for operating the engine based on a thermal runaway prediction model, such as that described in step 302 of the Fig. 3 described model.

[0045] At step 401, similar to step 301, the Fig.3, the vehicle operating conditions from a controller (e.g. the controller 12 in Fig. 2) Estimated. The controller obtains measurements from various sensors in the engine system and estimates operating conditions, such as engine load, vehicle speed, engine rpm, engine coolant temperature, thermostat position, vehicle cabin temperature, and ambient temperature.

[0046] At step 402, the actual coolant temperature at the radiator outlet T RO ' measured by a temperature sensor. As one example, the temperature sensor may be located at a radiator outlet, where the radiator outlet is an opening in the radiator shell and is directly coupled to a lower hose. As another example, the temperature sensor may be coupled to the radiator end tank. As yet another example, the temperature sensor may be coupled to the radiator's lower hose.

[0047] At step 403, virtual temperature signals are calculated based on a thermal state estimator. As an example, the thermal state estimator may be a Kalman filter. Inputs to the thermal state estimator may include the measured coolant temperature at the radiator outlet from step 402. The thermal state estimator may be calculated based on a thermal runaway prediction model, such as the one described in step 302 of the Fig.3 described model. The virtual temperature signals can include engine temperature and radiator temperature. When the thermostat is in a second position (coolant bypasses the radiator), the readings from the temperature sensor tend to approach the engine temperature. When the thermostat is in a first position (coolant flows through the radiator), the readings from the temperature sensor approach the radiator temperature. Thus, both engine temperature and radiator temperature can be derived based on the measured coolant temperature at the radiator outlet. As an example, the measured coolant temperature at the radiator outlet T RO in the thermal instability model presented in equations 1-16 and the engine temperature T eng can be resolved as a virtual engine temperature. Alternatively, the radiator temperature T radas another example, be considered unknown and solved by equations 1-16 as a virtual cooler temperature.

[0048] At step 404, method 400 operates the engine based on the estimated virtual temperature signals. For example, the radiator fan, coolant pump, and valves may be controlled based on the estimated virtual signals.

[0049] Fig. 5 illustrates engine operating parameters (i.e., engine torque 501, engine coolant temperature 502, thermostat position 503, radiator outlet coolant temperature 504, radiator outlet coolant flow rate 505, and radiator fan speed 506), while the cooling system state is compared with the Fig. 3-4. The x-axis indicates time, increasing from left to right.

[0050] From T0 to T1, the engine coolant temperature 502 increases with increased engine torque 501. The thermostat is in a second position where the coolant bypasses the radiator to reduce engine warm-up time (as in Fig. 1B). At the radiator outlet, coolant may flow from the heater core outlet through the vent hose to the radiator outlet due to the low-pressure condition created by the coolant pump. The coolant temperature at the radiator outlet may rise. The flow rate at the radiator outlet is low.

[0051] At T1, in response to the engine coolant temperature 502 being higher than a threshold 512, the thermostat moves to the first position where coolant flows through the radiator. The coolant flowing through the radiator allows cooled coolant to flow from inside the radiator to the outside and sweep away the warmed coolant in the radiator outlet. Consequently, the coolant temperature 504 at the radiator outlet may first drop, then rise as warm coolant reaches the radiator outlet. The coolant flow rate at the radiator outlet increases as coolant flows from the radiator outlet to the inlet of the coolant pump (as shown in Fig. 1A).

[0052] If the engine coolant temperature 502 continues to rise to a threshold 511, the controller may turn on the cooling fan 506 at T2. Alternatively, the controller may increase the speed of the cooling fan 506 at T2. The cooling fan speed may increase in response to the increased engine speed. For example, the cooling fan speed may increase with increased coolant temperature.

[0053] In response to a decrease in engine torque at T3, the engine coolant temperature decreases. If the engine coolant temperature is below threshold 511 at T4, the controller may reduce the cooling fan speed. Alternatively, the controller may turn off the cooling fan at T4. If the engine coolant temperature drops further below threshold 512 at T5, the thermostat moves to the second position. Consequently, the coolant temperature at the radiator outlet T ROdue to the reverse vent flow in the vent hose.

[0054] At T6, engine torque and engine coolant temperature begin to rise. At T7, the thermostat moves to the first position in response to the engine coolant temperature being higher than threshold 512. Coolant flows through the radiator. Consequently, T RO and w RO rises.

[0055] In this way, a radiator malfunction can be predicted based on a thermal instability model without the need for additional hardware. Furthermore, by measuring the actual coolant temperature at a position between one end of a radiator core and a junction between a radiator's lower hose and a heater core outlet line, thermostat or radiator heat transfer degradation can be identified. Furthermore, by integrating the thermal instability model into a thermal state estimator, the temperatures of engine components can be estimated and used for engine control.

[0056] The technical effect of estimating the coolant temperature at a position between one end of a radiator core and a junction between a radiator lower hose and a heater core outlet line is that fluctuations in the coolant temperature can be better predicted. The technical effect of estimating the coolant flow rate at the radiator outlet when coolant bypasses the radiator is that reverse coolant flow from the heater core outlet to the radiator outlet can be incorporated into the thermal runaway model. The technical effect of building a model based on (e.g., as a mathematical function) the coolant temperature at the radiator outlet is that radiator malfunction can be predicted by estimating the fluctuations in the coolant temperature.The technical effect of comparing the estimated coolant temperature with the measured coolant temperature at the radiator outlet is that thermostat degeneration can be determined.

[0057] As one embodiment, a method for a cooling system comprises: adjusting a coolant flow with a thermostat, estimating a coolant temperature at a position between an end of a radiator core and a junction between a lower hose of a radiator and a heater core output line; and indicating a cooling system condition based on the estimated coolant temperature. In a first example of the method, the thermostat is in a first position for coolant to flow through the radiator and in a second position for coolant to bypass the radiator. A second example of the method optionally includes the first example and further includes where the cooling system condition includes a radiator malfunction, radiator life, and thermostat degradation.A third example of the method optionally includes one or more of the first and second examples, and further includes indicating the radiator state based on a fluctuation in the estimated coolant temperature. A fourth example of the method optionally includes one or more of the first to third examples, and further includes indicating the radiator state based on the amplitude of the fluctuation. A fifth example of the method optionally includes one or more of the first to fourth examples, and further includes indicating the radiator state when the number of fluctuations in the estimated coolant temperature is greater than a threshold. A sixth example of the method optionally includes one or more of the first to fifth examples, and further includes the estimated coolant temperature being the coolant temperature at a radiator outlet.A seventh example of the method optionally includes one or more of the first through sixth examples, and further includes where the estimated coolant temperature is the coolant temperature at a radiator end tank. An eighth example of the method optionally includes one or more of the first through seventh examples, and further includes measuring the coolant temperature at a location between an end of a radiator core and a junction between a lower hose of a radiator and a heater core output line using a sensor. A ninth example of the method optionally includes one or more of the first through eighth examples, and further includes indicating thermostat degeneration by comparing the measured coolant temperature to the estimated coolant temperature.

[0058] As another embodiment, a method for a cooling system comprises: stopping coolant flow from a thermostat to a radiator; determining a coolant flow rate from a radiator core to a radiator end tank; estimating a coolant temperature at a position between an end of a radiator core and a junction between a lower hose of a radiator and a heater core output line; and indicating degradation of the cooling system based on the estimated coolant temperature. In a first example of the method, coolant flow from the thermostat to the downstream radiator is zero when coolant flow is stopped. A second example of the method optionally includes the first example and further includes estimating an engine temperature based on the estimated coolant temperature and operating the engine in response to the estimated engine temperature.A third example of the method optionally includes one or more of the first and second examples, and further includes estimating a radiator temperature based on the estimated coolant temperature and operating a radiator fan in response to the estimated radiator temperature. A fourth example of the method optionally includes one or more of the first to third examples, and further includes estimating the coolant temperature based on a measured coolant temperature at a location between the end of a radiator core and the junction between the lower hose of a radiator and the heater core output line using a thermal state estimator.

[0059] As yet another embodiment, a vehicle system comprises: a pump upstream of an engine for pumping coolant to the engine; a radiator having a radiator core and an end tank; a lower hose directly coupled to the end tank; a heater core; a thermostat downstream of the engine for controlling coolant flow to the radiator; and a controller configured with computer-readable instructions stored in non-transitory memory to: estimate a coolant temperature at a location between an end of a radiator core and a junction between a lower hose of a radiator and a heater core output line; predict a malfunction of the radiator based on the estimated coolant temperature; and operate the engine based on the predicted malfunction of the radiator.In a first example of the system, the end tank of the radiator is in direct fluid communication with both an inlet of the pump and an outlet of the heater core. A second example of the system optionally includes the first example and further includes the controller further configured to predict a malfunction of the radiator based on a coolant flow rate from the heater core to the radiator end tank when the radiator is bypassed. A third example of the system optionally includes one or more of the first and second examples and further includes the controller further configured to determine thermostat degeneration. A fourth example of the system optionally includes one or more of the first through third examples and further includes the controller further configured to adjust a radiator fan in response to a predicted malfunction of the radiator.

[0060] It should be noted that the example control and estimation routines contained herein may be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be executed by the control system, including the controller in combination with various sensors, actuators, and other engine components. The particular routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, various illustrated acts, operations, and / or functions may be performed in the illustrated order, in parallel, or in some cases omitted.Likewise, the processing order is not required to achieve the features and advantages of the embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly, depending on the particular strategy employed. Further, the described acts, operations, and / or functions graphically represent code to be programmed into a non-transitory memory of the computer-readable storage medium in the engine control system, in which the described acts are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.

[0061] It should be appreciated that the configurations and routines disclosed herein are exemplary in nature and that these particular embodiments are not intended to be limiting, as many variations are possible. For example, the above technology may be applied to a V6, an I-4, an I6, a V12, a horizontally opposed four-cylinder engine, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or characteristics disclosed herein. List of reference symbols 2 Fuel system 10 Engine 12 Control device 30 combustion chamber 32 combustion chamber walls 36 pistons 40 Crankshaft 42 intake passage 46 intake manifold 48 Exhaust passage 52 intake valve 54 Exhaust valve 62 Throttle 64 throttle valve 66 Fuel injection 68 electronic drivers 70 exhaust aftertreatment system 80 Diesel oxidation catalyst (DOC- diesel oxidation catalyst) 82 Catalyst 84 urea atomizers 86 diesel particulate filters (DPF - diesel particulate filter) 94 Actuator 100 Cooling system 102 Microprocessor unit 104 input / output ports 106 Read-only memory chip 108 Random Access Memory 110 life support storage units 112 Temperature sensor 114 Cooling sleeve 118 Hall effect sensor 120 Air mass flow sensor 122 Manifold air pressure sensor 123 Boost pressure sensor 126 exhaust gas sensor 130 Input device 132 vehicle operators 134 Pedal position sensor 140 heating core 140A cluster indicator 140E vent hose 141 coolers 142 Radiator end tank 143 lower hose 144 Passage 145 Thermostat 146 Coolant pump 147 upper hose 148 Radiator fan 149 Temperature sensor 150 connection point 151 Heater core outlet line 152 Sensor 153 Radiator block 154 front tank 162 Compressor 164 turbines 300 procedures 400 procedures 501 engine torque 502 Engine coolant temperature 503 Thermostat position 504 Coolant temperature 505 Coolant flow rate 506 radiator fan 511 threshold 512 threshold

Claims

[1] A method for a cooling system (100) comprising: Adjusting a coolant flow with a thermostat (145) based on the thermostat position, estimating a coolant temperature (T RO ) at a position between one end of a radiator block (153) and a connection point (150) between a lower hose (143) of a radiator (141) and a heater core output line (151); and Specify a cooling system condition based on the estimated coolant temperature (T RO ), wherein the cooling system condition includes a malfunction of the radiator (141), a radiator life, and a thermostat degeneration. [2] The method of claim 1, wherein the thermostat (145) is in a first position for the coolant to flow through a radiator (141) and in a second position for the coolant to bypass the radiator (141). [3] The method of claim 1, further comprising indicating the cooling system state based on a variation in the estimated coolant temperature (T RO ). [4] The method of claim 3, further comprising indicating a malfunction of the cooler (141) based on an amplitude of the fluctuation. [5] The method of claim 4, further comprising indicating the cooler condition when a number of fluctuations in the estimated coolant temperature (T RO ) is greater than a threshold. [6] The method of claim 1, wherein the estimated coolant temperature (T RO ) the coolant temperature (T RO ) at a radiator outlet. [7] The method of claim 1, wherein the estimated coolant temperature (T RO ) the coolant temperature (T RO ) on a radiator end tank (142). [8] The method of claim 1, further comprising measuring the coolant temperature (T RO) at the position between the end of the radiator block (153) and the connection point (150) between the lower hose (143) of a radiator (141) and the heater core output line (151) by means of a sensor (149). [9] The method of claim 8, further comprising indicating the thermostat degeneration by comparing a measured coolant temperature (T RO ) with the estimated coolant temperature (T RO ). [10] A method for a cooling system (100) comprising: Stopping the flow of coolant from a thermostat (145) to a radiator (141); Determining a coolant flow rate from a heater core to a radiator end tank (142); Estimating a coolant temperature (T RO ) at a position between one end of a radiator block (153) and a connection point (150) between a lower hose (143) of a radiator (141) and a heater core output line (151); and Indicating a degeneration of the cooling system (100) based on the estimated coolant temperature (T RO ). [11] The method of claim 10, wherein the coolant flow rate from the thermostat (145) to the radiator (141) downstream of the thermostat (145) is zero when the coolant flow is stopped. [12] The method of claim 10, further comprising estimating an engine temperature based on the estimated coolant temperature (T RO ) and operating an engine in response to the estimated engine temperature. [13] The method of claim 10, further comprising estimating a radiator temperature based on the estimated coolant temperature (T RO ) and operating a cooling fan in response to the estimated radiator temperature. [14] The method of claim 10, wherein the engine temperature is determined based on a measured coolant temperature (T RO) at the position between the end of the radiator block (153) and the connection point (150) between the lower hose (143) of the radiator (141) and the heater core output line (151) is estimated via a thermal state estimation function.

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