METHOD AND VEHICLE SYSTEM FOR CONTROLLING COOLANT FLOW THROUGH MULTIPLE ENGINE COMPONENTS

Abstract

Procedure, comprehensive: Estimating a transmission oil temperature (TOT) at a torque converter (TC) outlet based on a torque converter slip ratio; and Adjusting the flow of coolant through each of an air conditioning (AC) condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of a coolant circuit to maintain the estimated transmission oil temperature (TOT) below a threshold in response to the TOT being estimated based on a torque converter slip ratio.

Description

AREA

[0001] The present application relates to methods and systems for controlling a flow of coolant through a plurality of engine components. GENERAL STATE OF THE ART AND SUMMARY

[0002] Vehicle systems may include multiple coolant loops to circulate coolant through various sets of engine components. The coolant flow may absorb heat from some components (thereby accelerating cooling of those components) and transfer the heat to other components (thereby accelerating heating of those components). For example, a high-temperature coolant loop may circulate coolant through an engine to absorb engine waste heat. The coolant may also absorb heat dissipated by one or more of an EGR cooler, an exhaust manifold cooler, a turbocharger cooler, and a transmission oil cooler. Heat from the heated coolant may be transferred to a heater core (for heating a vehicle cabin) and / or vented to the atmosphere after flowing through a car radiator that includes a fan.As another example, a low-temperature coolant loop may circulate coolant through a charge air cooler. When needed (such as when cabin air conditioning is required), the coolant in the low-temperature loop may additionally be pumped through the condenser of the air conditioning (AC) system to absorb heat removed by an AC system refrigerant at the condenser. Heat from the heated coolant may be dissipated to the atmosphere after flowing through another vehicle radiator that includes a fan. An example of such a vehicle coolant system is shown in US 2015 / 0 047 374 A1. Another example of a coolant system is shown in US 2015 / 0 040 874 A1. Therein, a heat exchanger enables heat exchange between a charge air cooling coolant circuit and a condenser refrigerant circuit.

[0003] Further vehicle systems for controlling the flow of coolant through several engine components are shown in the documents DE 10 2013 205 229 A1, DE 10 2013 205 009 A1, DE 10 2013 204 703 A1 and DE 10 2013 205 124 A1.

[0004] However, the inventors of the present invention have recognized potential problems with such coolant systems. For example, if the coolant flow through the transmission oil cooler (TOC) is underestimated, the coolant system may boil over. In particular, in engine systems that include an automatic transmission, the coolant flowing through the transmission oil cooler (e.g., in the high-temperature coolant loop) is used to cool transmission oil drawn from the torque converter. This is because the oil is hottest at this location due to the viscous action of the torque converter. Based on the oil temperature, a TOC valve is actuated to divert transmission oil for heat exchange with the coolant system.However, the oil temperature is estimated at the oil pan, which can be significantly cooler than the actual temperature of the oil flowing from the torque converter, such as when the torque converter is uphill or experiencing slippage, or during transmission shifts. If the coolant flow is adjusted based on the oil temperature at the oil pan, the actual coolant flow may be less than the required coolant flow, causing the coolant to boil over. In addition to affecting the transmission, this can also affect all engine components that share coolant with the transmission via the coolant loop, such as the AC system, intercooler, cylinder head, etc.

[0005] The invention is therefore based on the object of mitigating the aforementioned problems and creating an improved method and an improved vehicle system of the aforementioned type that avoid the aforementioned problems and advantageously develop the prior art. In particular, boilover of the coolant and the associated deterioration of the engine components are to be avoided, and efficient cooling of the engine components is to be achieved.

[0006] To achieve the stated object, a method according to claim 1 and a vehicle system according to claim 11 are proposed. Preferred embodiments of the invention are the subject of the dependent claims.

[0007] To mitigate the aforementioned problems, the method includes adjusting a coolant flow through each of an air conditioning condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of a coolant circuit to maintain an estimated transmission oil temperature (TOT) below a threshold, where the TOT is estimated based on a torque converter slip ratio. In this way, transmission temperatures can be better maintained while sharing coolant with other engine components.

[0008] As one example, each of a condenser of an AC system and a CAC may be coupled to different branches of a coolant loop downstream of a proportional valve, with coolant being directed into the loop via a coolant pump. The condenser may be further coupled to a refrigerant loop of the AC system, while the coolant loop may be further coupled to an oil loop of a transmission via a transmission valve at a transmission oil cooler (TOC). The oil loop may include an oil pan from which oil is drawn and directed through a transmission, a torque converter, and the TOC. A temperature sensor coupled to the oil pan may be configured to provide an estimate of a transmission oil temperature (TOT) at the oil pan.During conditions where heat may be generated at the torque converter, such as when the torque converter slip ratio is above a threshold, the controller may adjust the coolant flow through the TOC based on a TOT estimate derived based on operating conditions at the torque converter, rather than the TOT estimate measured by the temperature sensor. Alternatively, the controller may compare the two TOT estimates and use the higher of the two to adjust the coolant flow through the TOC. Thus, during these conditions, the cabin cooling demand and the engine cooling demand may be significantly less than the cooling demand at the TOC. The controller may then adjust the pump output as well as a position of the proportional valve to provide a desired coolant flow rate through the coolant circuit components, including the TOC, to provide the required cooling.In this way, by adjusting coolant distribution through a TOC based on torque converter conditions, including a slip ratio, coolant boiling can be better avoided. By relying on a derived TOT estimate, the need for additional temperature sensors to regulate coolant boiling problems is reduced, providing component reduction benefits. Furthermore, by using an existing fuel-efficient coolant pump for TOT control, the vehicle's electrical power consumption is reduced, providing additional fuel economy benefits. Overall, engine cooling performance is improved.

[0009] It should be understood that the foregoing summary is provided to introduce, in simplified form, a selection of concepts further described in the detailed description. It is not intended to identify important or essential features of the claimed subject matter, the scope of which is defined solely in the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that overcome any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an exemplary embodiment of a supercharged vehicle system. Fig. Figure 2 shows an exemplary embodiment of a coolant system connected to the engine system of Fig. 1 is coupled. Fig. Figure 3 shows a state diagram illustrating the different operating modes of the coolant system. Fig. Figure 4 shows a high-level flowchart illustrating a routine that may be implemented to operate the coolant system based on cooling demand and engine operating conditions. Fig. Figure 5 shows a high-level flow diagram illustrating a routine that may be implemented to divide coolant flow between different engine components. Fig. 6A-6B show example diagrams illustrating the relationship between coolant pump power, AC head pressure, and coolant flow rate. Fig. Figure 7 shows a high-level flowchart illustrating a routine that may be implemented to diagnose an AC system degradation. Fig. Figure 8 shows a high-level flowchart illustrating a routine that may be implemented to adjust coolant flow through a TOC based on torque converter slip. Fig. 9-12 show example settings of the coolant pump power and the split of the coolant flow between an AC and a charge air cooler of a coolant system in response to a change in cooling demand and engine operating conditions. DETAILED DESCRIPTION

[0010] Methods and systems are provided for improving the performance of components cooled by an engine coolant system, such as the coolant system of Fig. 2, which is connected to the engine system Fig. 1. The coolant system can be operated in one of a variety of operating states, with the coolant system transitioning between the different states in response to engine operating conditions and changes in cooling demand (as in Fig. 3). An engine controller may be configured to perform a control routine, such as the exemplary routine of Fig. 4-5, to coordinate adjustments to a coolant pump output and the position of a proportional valve to vary the flow of coolant through the various components of the coolant system to meet the cooling demand with reduced parasitic losses. For example, the controller may refer to a diagram, such as the example diagrams from Fig. 6A-6B to determine a pump power and coolant flow rate at which air conditioning performance is optimized. Additionally, the controller may adjust the proportion of coolant flowing through a transmission oil cooler in the coolant loop based on torque converter slip. Example settings are described with reference to Fig. 9-12. In addition, the controller may use differences between an expected AC head pressure and an actual AC head pressure to diagnose a degradation of the AC system, as described with reference to Fig. 7 described.

[0011] Fig. 1 schematically illustrates aspects of an exemplary engine system 100 including an engine 10. In the illustrated embodiment, the engine 10 is a supercharged engine coupled to a turbocharger 13 including a compressor 114 driven by a turbine 116. Specifically, fresh air is introduced into the engine 10 along an intake passage 42 via an air cleaner 112 and flows to the compressor 114. The compressor may be any suitable intake air compressor, such as an electric motor-driven or drive shaft-driven supercharger compressor. However, in the engine system 10, the compressor is a turbocharger compressor mechanically coupled to the turbine 116 via a shaft 19, with the turbine 116 being driven by expanding engine exhaust gases. In one embodiment, the compressor and turbine may be coupled within a twin-scroll turbocharger.In another embodiment, the turbocharger may be a variable turbine geometry (VTG) turbocharger, wherein the turbine geometry is actively varied as a function of engine speed.

[0012] As in Fig. 1, the compressor 114 is coupled to the throttle valve 20 through the charge air cooler (CAC) 18 (also referred to herein as an intercooler). The throttle valve 20 is coupled to the engine intake manifold 22. From the compressor, the compressed air charge flows through the charge air cooler 18 and the throttle valve to the intake manifold. The charge air cooler may, for example, be an air-to-air heat exchanger. A detailed description of the cooling circuit coupled to the CAC is provided below with reference to Fig. 2. In the Fig. In the embodiment shown in Figure 1, the pressure of the air charge within the intake manifold is sensed by the manifold air pressure (MAP) sensor 124. Since flow through the compressor can heat the compressed air, a downstream CAC 18 is provided so that a boosted inducted air charge can be cooled prior to being fed into the engine intake.

[0013] One or more sensors may be coupled to an inlet of the compressor 114. For example, a temperature sensor 55 may be coupled to the inlet for estimating a compressor inlet temperature, and a pressure sensor 56 may be coupled to the inlet for estimating a compressor inlet pressure. As another example, a humidity sensor 57 may be coupled to the inlet for estimating a humidity of an air charge entering the compressor. Still other sensors may include, for example, air-fuel ratio sensors, etc. In other examples, one or more of the compressor inlet conditions (such as humidity, temperature, pressure, etc.) may be inferred based on engine operating conditions.Additionally, when EGR is enabled, the sensors can estimate temperature, pressure, humidity, and air-fuel ratio of the air charge mixture, including fresh air, recirculated compressed air, and residual exhaust gases taken in at the compressor inlet.

[0014] The engine system 100 may further include an air conditioning (AC) system 82, for example, as part of a vehicle HVAC system 84. The AC system 82 may include various components, such as a compressor for pumping refrigerant, an evaporator for evaporating refrigerant, a condenser for condensing refrigerant, and various temperature sensors. The AC system may be turned on or operated in response to a vehicle operator request to cool the vehicle cabin, dehumidify the cabin air, and / or defrost. As discussed herein, when the AC system is turned on, heat generated by the operation of the AC system (specifically, by the AC system's condenser) may be dissipated into a (first) coolant-based cooling circuit coupled to the CAC, the HVAC system, and a vehicle radiator, wherein the first cooling circuit is not coupled to the engine manifold, the cylinder head, or an EGR cooler.Specifically, the condenser can be used to dissipate heat, while the AC evaporator absorbs the heat generated due to AC operation. Overall, the AC system converts heat into work (Q_evap + W_mech). The exhaust manifold, cylinder head, and EGR cooler can instead be coupled to a different coolant-based cooling circuit (e.g., another high-temperature coolant circuit). Additionally, the engine oil can be cooled and heated by the high-temperature coolant circuit. By adjusting the power of a first-circuit pump and a proportional valve, the coolant flow through the AC system and the CAC can be divided based on their cooling needs, reducing parasitic losses to the system and improving fuel economy. Additionally, control of the cooling circuit and CAC temperature can be accelerated while reducing overheating.Specifically, an AC head pressure is determined for the AC system. The AC head pressure is the AC system pressure at a location downstream of the AC compressor and upstream of an expansion valve. Thus, it is the pressure on the "high side" of the AC system, located after the compressor and generally before the condenser. As discussed herein, the AC head pressure is used in the control of the air-cooled AC system for clutch, variable displacement compressor, and fan control.

[0015] The intake manifold 22 is coupled to a series of combustion chambers 30 through a series of intake valves (not shown). The combustion chambers are further coupled to the exhaust manifold 36 via a series of exhaust valves (not shown). In the illustrated embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold may include a plurality of exhaust manifold sections. Configurations including a plurality of exhaust manifold sections may allow wastewater from different combustion chambers to be routed to different locations in the engine system.

[0016] In one embodiment, each of the exhaust and intake valves may be electronically actuated or controlled. In another embodiment, each of the exhaust and intake valves may be cam-actuated or controlled. Whether electronically actuated or cam-actuated, the timing of the opening and closing of the exhaust and intake valves can be adjusted as required for the desired combustion and emissions control performance.

[0017] One or more fuels, such as gasoline, alcohol-fuel blends, diesel, biodiesel, compressed natural gas, etc., can be supplied to the combustion chambers 30 via the injection system 66. The fuel can be supplied to the combustion chambers via direct injection, port injection, throttle body injection, or a combination thereof. Combustion in the combustion chambers can be initiated via spark ignition and / or compression ignition.

[0018] As in Fig. 1, exhaust gas from one or more exhaust manifold sections is directed to the turbine 116 to drive the turbine. If reduced turbine torque is desired, some exhaust gas may instead be directed through the wastegate 90, bypassing the turbine. In particular, the wastegate actuator 92 may be actuated to open to vent at least a portion of the exhaust pressure from upstream of the turbine 116 via the wastegate 90 to a location downstream of the turbine. By reducing the exhaust pressure upstream of the turbine, the turbine speed may be reduced, which in turn aids in boost control. The combined flow from the turbine and wastegate then flows through the emissions control 170.In general, one or more emissions control devices 170 may include one or more exhaust aftertreatment catalysts configured to catalytically treat the exhaust stream and thereby reduce an amount of one or more substances in the exhaust stream. For example, an exhaust aftertreatment catalyst may be configured to reduce NO. x from the exhaust gas stream when the exhaust gas stream is lean, and the stored NO x to reduce when the exhaust flow is rich. In further examples, an exhaust aftertreatment catalyst may be configured to reduce NO x to disproportionate or NO xusing a reducing agent. In yet further examples, an exhaust aftertreatment catalyst may be configured to oxidize hydrocarbon and / or carbon monoxide residues in the exhaust stream. Different exhaust aftertreatment catalysts with such functionality may be disposed in washcoats or elsewhere in the exhaust aftertreatment stages, either separately or together. In some embodiments, the exhaust aftertreatment stages may include a regenerable soot filter configured to trap and oxidize soot particulates in the exhaust stream.

[0019] The treated exhaust gas from emissions control system 170 may be released to the atmosphere in whole or in part via exhaust passage 35. However, depending on operating conditions, a portion of the residual exhaust gases may instead be redirected to EGR passage 50, through EGR cooler 51 and EGR valve 52, to the inlet of compressor 114. Thus, EGR passage 50 couples the engine exhaust manifold downstream of turbine 116 to the engine intake manifold upstream of compressor 114.

[0020] The EGR valve 52 can be opened to admit a controlled amount of cooled exhaust gas into the compressor inlet for desired combustion and emissions control performance. In this manner, the engine system 10 is configured to provide external low-pressure (LP) EGR by taking exhaust gas from downstream of the turbine 116. The EGR valve 52 can also be configured as a continuously variable valve. However, in an alternative example, the EGR valve 52 can be configured as an on / off valve. The rotation of the compressor, in addition to the relatively long LP EGR flow path in the engine system 10, provides excellent homogenization of the exhaust gas into the intake air charge. Furthermore, the arrangement of the EGR takeoff and mixing points provides very effective cooling of the exhaust gas for increased available EGR mass and improved power.In further embodiments, the engine system may further include a high pressure EGR flow path wherein exhaust gas is drawn from upstream of the turbine 116 and recirculated downstream of the compressor 114 to the engine intake manifold.

[0021] The EGR cooler 51 may be coupled to the EGR passage 50 for cooling the EGR supplied to the compressor. Additionally, one or more sensors may be coupled to the EGR passage 50 to provide details regarding the composition and condition of the EGR. For example, a temperature sensor may be provided to determine a temperature of the EGR, a pressure sensor may be provided to determine a pressure of the EGR, a humidity sensor may be provided to determine a humidity or water content of the EGR, and an air-fuel ratio sensor 54 may be provided to estimate an air-fuel ratio of the EGR. Alternatively, EGR conditions may be inferred by the one or more temperature, pressure, humidity, and air-fuel ratio sensors 55-57 coupled to the compressor inlet.An opening of the EGR valve can be adjusted based on engine operating conditions and EGR conditions to provide a desired amount of engine dilution.

[0022] The engine system 100 may further include the control system 14. The control system 14 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). For example, the sensors 16 may include the exhaust gas sensor 126 located upstream of the emissions control device, the MAP sensor 124, the exhaust gas temperature sensor 128, the exhaust gas pressure sensor 129, the compressor inlet temperature sensor 55, the compressor inlet pressure sensor 56, the compressor inlet humidity sensor 57, and the EGR sensor 54. Other sensors, such as additional pressure, temperature, air-fuel ratio, and composition sensors, may be coupled to various locations in the engine system 100.The actuators 81 may include, for example, the throttle 20, the EGR valve 52, a compressor recirculation valve, the wastegate 92, and the fuel injector 66. The control system 14 may include a controller 12. The controller may receive input data from the various sensors, process the input data, and trigger various actuators in response to the processed input data based on an instruction or code programmed therein according to one or more routines. Example control routines are described herein with respect to FIG. Fig. 4, Fig. 5 and Fig. 7 described.

[0023] Now, with reference to Fig. 2 shows an exemplary cooling system 200 which is connected to the engine of Fig. 1. Accordingly, the engine may be coupled to a passenger car or other road vehicle. The cooling system allows defrost heat recovered from operation in defrost mode to be transferred to a CAC, thereby accelerating engine warm-up. Specifically, the flow through the heated CAC is used to restrict coolant cooling, allowing the already warm air from the compressor and conduction / convection from the engine to warm the air, improving engine performance during cold conditions.

[0024] The coolant system 200 includes a first coolant circuit or loop 202 and a second coolant circuit or loop 204, each coupled to different sets of engine system components. The first coolant circuit 202 represents a low-temperature coolant loop that includes a low-temperature (LT) radiator 206 and associated fan 207, a coolant pump 208, a water-to-air charge air cooler (CAC) 210, and an AC system condenser 260. The coolant pump 208 may be a variable-power electric pump driven by an electric motor. The first coolant circuit 202 further includes a proportional valve 250, which in the depicted example is configured as a three-way valve. Additionally, a transmission oil cooler (TOC) 220 is coupled to the first coolant circuit.The AC system condenser 260 may be coupled to the air conditioning system 270, which is part of a larger vehicle HVAC system (such as the AC system of . Fig. 1). The AC system 270 may include a refrigerant circuit 272 that circulates refrigerant through the AC system to provide cooling via the compression and expansion cycles of the refrigerant, with the refrigerant circuit 270 connected to the coolant circuit at the condenser 260. The refrigerant circuit may include a thermal expansion valve 272, an AC clutch 274, and an AC compressor 276. The expansion valve is configured to control the amount of refrigerant flowing into the condenser, thereby controlling superheat at the evaporator outlet. The thermal expansion valve thereby acts as the AC system's metering device. The AC clutch is configured to control the refrigerant flow out of the AC compressor. In this way, each of the refrigerant and coolant can circulate through the AC condenser.

[0025] The TOC 220 includes a cooler and a heater for regulating the temperature of transmission oil flowing therethrough. A transmission oil circuit 280 may be coupled to each of the first coolant loop 202 and the second coolant loop 204 at the TOC. The transmission oil circuit 280 allows oil drawn from the oil pan 282 to flow through a transmission 284. A temperature sensor 286 coupled to the transmission circuit, such as at the oil pan, provides the controller 12 with an estimate of the transmission oil temperature (TOT). The TOT may be used as input by the controller 12 to vary the power of the pump 208 and to also vary the coolant distribution via adjustments to the position of the proportional valve 250. By exchanging heat with the coolant circuits 202, 204, a temperature of oil at the transmission may be maintained within a threshold range, thereby optimizing transmission performance.The heat dissipated into the oil at the transmission can be advantageously used to heat the engine. Likewise, the heat dissipated into the coolant circuit via the engine can be advantageously used to heat the transmission oil, thereby warming the engine.

[0026] During conditions where there is a cooling demand on the AC condenser (such as when the AC system is turned on during a cabin cooling or defrost request), a cooling demand on the CAC (such as when the engine intake compressor is operating), or a cooling demand on the transmission oil cooler (TOC) (such as when the transmission oil temperature is above a threshold), the coolant pump 208 may be actuated to flow coolant into the circuit 202. Additionally, the position of the proportional valve 250 is adjusted to vary the flow rate of coolant through the different circuit components based on their respective cooling demands.For example, the proportional valve 250 may be adjusted to direct a first amount of coolant to a first subloop 242 including the CAC 210, a second amount of coolant to the second subloop 244 including the AC condenser 260, and a remaining third amount of coolant to the main loop 246 including the TOC 220. As discussed herein, by adjusting a power of the pump 208 in coordination with adjusting the position of the proportional valve 250, a coolant flow rate through each component may be adjusted to meet a respective cooling demand while reducing parasitic losses at the pump and improving overall engine fuel economy.

[0027] The desired coolant flow rate for the AC condenser can be set according to the measured coolant temperature. The desired coolant flow rate can be a flow rate that corresponds to minimal parasitic losses, as determined using mapping and calibration. The flow rate can be further adjusted based on the difference between the expected AC head pressure and the actual AC head pressure. The desired coolant flow rate in all branches is then passed to an inverse hydraulic model, which determines the proportional valve position and the coolant pump speed to achieve the required flow rate. In this way, the minimum pump flow rate is achieved given the branch-specific flow requirements and overall flow requirements.

[0028] For example, during conditions where CAC cooling demand, AC cooling demand, and TOC cooling demand exist and none of the cooling demands are met, the coolant system may be operated in a continuous control mode, with flow through each loop determined based on the feedforward and feedforward components. For example, coolant flow through the CAC loop may be determined feedforward based on mass air flow (e.g., MAF, measured downstream of the CAC) and CAC coolant temperature (at the inlet to the CAC). The first feedforward value of AC head pressure may be derived from CAC coolant temperature. The feedforward value of coolant flow may further be based on TCT (upstream airflow into the CAC) and adjusted feedforward based on manifold charge temperature (MCT).As one example, if the MCT is above a target temperature, more coolant is flowed to cool it. As another example, if the MCT is cooler than the target temperature, less coolant is flowed to limit cooling. Similarly, coolant flow through the AC loop may be determined feedforward based on AC head pressure and adjusted feedforward based on AC head pressure. As one example, if the AC head pressure is above a target pressure, more coolant may flow through the AC system to cool the AC system and reduce pressure. As another example, if the AC head pressure is below the target pressure, coolant flow through the AC system may be restricted to limit cooling of the AC system and increase AC head pressure.Furthermore, the coolant flow through the TOC loop can be determined in a feedforward manner based on torque converter slip and adjusted in a feedforward manner based on transmission oil temperature. As an example, if the transmission overheats (which can often occur in automatic transmissions when drive torque passes through an open fluid coupling, such as an open torque converter), the coolant flow can be adjusted. Transmission overheating can be indicated by transmission oil temperature (TOT). Thus, as TOT increases, the amount of coolant flow can be increased. Accordingly, if one of the loops has no cooling demand, for example, if there is no demand for air conditioning and coolant flow through the AC loop is not required, the coolant flow through that branch can be reduced to a minimum flow.After determining the required coolant flow through each branch, a pump power command can be determined, and a proportional valve positioning can be determined. In one example, if there is no cooling demand at any branch, coolant flow can be supplied to each branch at a minimum flow rate, and the pump can be operated at a minimum speed. This allows cooling to be quickly increased if the cooling demand subsequently increases (such as in response to a sudden air conditioning demand). Fig. Figure 6A shows a 3D map of the relationship between the optimal coolant flow rate, the CACCT coolant temperature, and the AC head pressure. Fig. Figure 6B shows a 2D section of the figure from Fig. 6A and point 614 corresponds to a point on the optimal curve 602 from Fig. 6A, which shows an optimal flow rate, a specific CACCT coolant temperature, and the corresponding reference AC head pressure (ACPRES). With a minimum flow, the coolant temperature available for a transient condition or even a demand can be quickly known, accelerating the delivery of the exact cooling flow. Additionally, if the flow in any branch is stalled, there is a risk of boilover, which is addressed by adjusting to provide the minimum flow. It is understood that stalling the coolant flow is only performed under specific, carefully quantified conditions.

[0029] In the first coolant circuit 202, the coolant pump 208 is configured to pump hot coolant taken from the condenser 260 and CAC 210 into the radiator 206 so that heat can be dissipated to the environment. Specifically, ambient air may flow through the radiator 206 and thereby take in air taken off at the radiator. The CAC 210 may be configured to cool a compressed intake air charge taken in by a compressor before the air charge is supplied to the engine intake. During boosted engine operation, intake air compressed at a compressor is supplied to the engine after passing through the CAC (such as the CAC 18 of Fig. 1). Heat from the air is transferred into the coolant flowing through the CAC.

[0030] When the cooling demand at the CAC 210 is met, the proportional valve 250 is adjusted by a motor controller to a position such that operation of the coolant pump 208 forces more coolant along the first subloop 242 and diverts coolant away from the AC condenser 260 and TOC 220. In comparison, when the cooling demand at the AC condenser 260 is met, the proportional valve 250 is adjusted by the motor controller to a position such that operation of the coolant pump 208 forces more coolant along the second subloop 244 and diverts coolant away from the CAC 210 and TOC 220. In this manner, the valve 250 affects the TOC flow because the valve resistance varies across its movement.

[0031] In still other examples, when the cooling demand at the CAC and the AC is each met, the pump power and the position of the proportional valve may be adjusted to share the available coolant while meeting the cooling demand of each component. For example, when both demands are met, the coolant system may operate in an extreme mode with the pump power set to a maximum power (e.g., a maximum speed) and the proportional valve set to a position that provides a calibrated distribution of coolant flow between the AC and the CAC. In one example, the calibrated distribution includes the AC and the CAC each receiving 50% of the coolant flow.For example, if the sum of the AC and CAC demands results in more flow than the system can provide, then the controller can set the pump to a maximum setting (fully on) and divide the branch flows according to a predetermined distribution of the resource, such as by setting the valve to 50% (toward the CAC) (see, for example, "Extreme Mode 308" of . Fig. 3).

[0032] As another example, if there is no AC demand (AC is off) and the CAC demand is greater than the system can provide (such as when driving fast on a race track), the valve is set to 100% (which includes 100% flow toward the CAC) (see, for example, Priority CAC Mode 310 at Fig. 3). As yet another example, if the AC head pressure (ACPRES) is above a threshold (e.g., critically high) and the CAC load is low, the valve can be set to 5% (which implies 5% flow towards the CAC, and the remaining 95% flows towards the AC) (see, for example, “Priority AC Mode 312” from Fig. 3). Thus, the coolant pump output goes to both the AC condenser and the CAC and TOC, and the output of each of the AC condenser, CAC, and TOC mixes at the pump inlet. Consequently, if the engine is not boosted, hotter coolant exits the condenser, and colder coolant exits the CAC, which mixes with warm coolant at the pump inlet.

[0033] The second coolant circuit 204 represents a high-temperature circuit and includes the high-temperature radiator 216 and associated fan 217, and the engine block 218. Additionally, the transmission oil cooler (which also acts as a transmission oil heater) 220 may be coupled to the junction of the coolant circuit 202 and the coolant circuit 204. An engine-driven mechanical coolant pump may be coupled to the engine block 218 to pump coolant through the high-temperature (HT) coolant circuit 204. Additional components coupled to the HT circuit 204 may include an EGR cooler, a heater core, a turbocharger cooler 290, and an exhaust manifold cooler 292.

[0034] The second coolant circuit 204 is a conventional coolant circuit and circulates coolant through the internal combustion engine 218 to absorb engine waste heat and distribute the heated coolant to the radiator 216 and / or the heater core. The radiator 216 may include a radiator fan 217 to improve cooling efficiency. The second cooling circuit may also circulate coolant through an EGR cooler connected to the EGR system (from Fig. 1). Specifically, waste heat is dissipated at the EGR cooler during EGR supply. The second coolant circuit also circulates coolant through the transmission oil cooler 220 and a turbocharger, absorbing the heat dissipated by these.

[0035] It should be understood that while the illustrated configuration shows specific components coupled to the first, low-temperature (LT) cooling circuit and other components coupled to the second, high-temperature (HT) cooling circuit, this is not intended to be limiting. In alternative examples, the selection of components for the HT or LT cooling circuit may be based on expedient routing and / or placement of the components relative to each other in the engine system. In one example, the AC condenser, the CAC, and a diesel fuel cooling component (if included) may be provided coupled to the LT circuit, as these components may be more effective in the LT coolant circuit due to the lower temperatures encountered there and to cool the LT coolant circuit to ambient temperature.

[0036] The engine-driven water pump circulates coolant through passages in the engine block 218, specifically through the intake and exhaust manifolds, through the engine head, and then through the engine block to absorb engine heat. From the engine, the coolant flows back to the engine after passing through the EGR cooler and radiator 216. Heat is transferred to the ambient air via the radiator 216 and fan 217. Thus, during conditions where EGR is supplied, heat dissipated at the EGR cooler can circulate through the engine 218 and be advantageously used to warm the engine, such as during cold ambient conditions. The engine-driven water pump may be coupled to the engine via a front end accessory drive (FEAD, not shown) and rotated in proportion to engine speed via a belt, chain, etc.In an example where the pump is a centrifugal pump, the pressure generated (and resulting flow) may be proportional to the crankshaft speed, which in the example is from . Fig. 2 is directly proportional to the engine speed. An auxiliary pump may also be included in the second cooling circuit to contribute to the coolant flow through the EGR system and the turbocharger. The coolant temperature may be regulated by a thermostatic valve, which may be kept closed until the coolant reaches a threshold temperature.

[0037] Fans 207, 217 may be coupled to radiators 206, 216, respectively, to maintain airflow through the radiators when the vehicle is moving slowly or is stopped while the engine is running. In some examples, the fan speed may be controlled by a controller. Alternatively, a fan 217 may be coupled to the engine-driven water pump. Still further, in some examples, heat exchangers 206 and 216 may be mounted close to each other so that a single fan can be used to draw air through both heat exchangers.

[0038] Hot coolant may also flow to the heater core via an auxiliary pump. An auxiliary pump may be used to circulate coolant through the heater core during situations where the engine 218 is off (e.g., electric-only operation) and / or to assist the engine-driven pump when the engine is running. Like the engine-driven pump, the auxiliary pump may be a centrifugal pump; however, the pressure (and resulting flow) generated by the auxiliary pump may be proportional to an amount of energy supplied to the pump by a system energy storage device (not shown).

[0039] The coolant system from Fig. 2 can be operated in one of a variety of modes and can transition between the modes based on engine operating conditions. A state diagram 300 of the different possible modes and conditions that trigger a transition between the modes is shown at Fig. 3 shown.

[0040] For example, the coolant may be in an off mode 302, where the first cooling loop's electric pump is off and the proportional valve is set to a position to shut off coolant flow to each of the AC system and the CAC. In this way, more of the coolant flow may be diverted away from the AC and CAC loops, and more coolant flow may be directed through the main loop. As another example, in response to fast vehicle travel without cabin cooling, the coolant system may transition to a priority CAC mode 310, where the pump power is increased and the proportional valve is positioned to prioritize flow to the CAC. The AC system may transition to a continuous control mode 304, where the pump and valve are controlled via the previously described control strategy to meet the cooling needs of all devices.As another example, in response to a turbocharger outlet temperature being above an available coolant temperature and the condensing temperature of the intake air being at a threshold moisture content and pressure, the coolant system may transition to a condensation control mode 306, wherein the proportional valve is set to a position where flow is controlled using the pump and valve to minimize or eliminate condensation generated at the inlet.As yet another example, in response to both high AC and CAC demand, both of which cannot be fully met even using the full power of the pump, the coolant system may transition to an extreme distribution mode 308, where the first coolant loop electric pump is fully on (at maximum power) and the proportional valve is set to a position where the coolant flow to each of the AC system and the CAC is divided by a predetermined amount, such as 50% toward the CAC and 50% toward the AC system, or 45% toward the CAC and 55% toward the AC system. The fixed ratio includes a higher ratio of coolant flow through the condenser relative to the charge air cooler.From the extreme mode, in response to an AC head pressure above the threshold and a CAC load below the threshold, such as when there is no longer a CAC cooling demand and the AC cooling demand is high enough to saturate the pump (e.g., more cooling than can be provided), the coolant system may transition to a priority AC mode 312, where the first cooling loop electric pump is fully on (operating at a highest power) and the proportional valve is set to a position to maximize coolant flow to the AC system (e.g., valve setting at 100% toward the AC system).Alternatively, in response to a CAC demand above the threshold (i.e., when the CAC is at the maximum available cooling capacity), with no cabin cooling demand at all (such as during high-speed driving on a race track), the coolant system may transition to a priority CAC mode 310, wherein the first cooling circuit electric pump is fully on (operating at a highest power level) and the proportional valve is set to a position to maximize coolant flow to the CAC (e.g., valve setting at 100% toward the CAC).

[0041] Now, with reference to Fig. 4 shows an exemplary routine 400 for adjusting the operation of an engine coolant system, such as the coolant system of Fig. 2, so that it meets the cooling needs of engine components while reducing parasitic losses and improving fuel economy. Instructions for carrying out method 400 and the other methods included herein may be executed by a controller based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the engine system, such as those described above with reference to Fig. 1. The controller may utilize engine actuators of the engine system to adjust engine operation according to the methods described below. For example, an engine controller may vary the power of an electric pump and adjust a position of the coolant system's low-temperature loop proportional valve based on one or more of an AC head pressure, a CAC temperature, and a transmission fluid temperature.

[0042] At 402, the method includes estimating and / or measuring engine operating conditions. For example, the controller may determine engine speed, engine load, driver demand, boost pressure, MAP, MAF, CAC temperature, cabin cooling demand, engine temperature, engine oil temperature, transmission oil temperature, etc.

[0043] At 404, the method includes determining a desired coolant flow through each component of the coolant system. For example, the controller may calculate a desired coolant flow through each of the AC subloop, CAC subloop, and TOC loop of the first coolant circuit. As at Fig. 5, the desired coolant flow through each loop may be determined based on the cooling demand of each component as well as a priority factor based on engine operating conditions. In one example, the controller may refer to a map, such as the example map of Fig. 6A and / or Fig. 6B to determine the required coolant flow through the AC loop to maintain a given AC head pressure at a given CAC coolant temperature. Therein, point 614 corresponds to the desired feedforward coolant flow after point 616. If the ACPRES is higher than the reference pressure (point 618), then more coolant is supplied to the feedforward flow, resulting in a larger net flow than at point 616.

[0044] For example, to determine the required coolant flow for optimal fuel economy when the pump is operating at a steady-state speed and the AC coolant flow is at its maximum, the controller can sample the coolant flow rate and ambient temperature to calculate the total parasitic losses. In particular, the figure from Fig. 6A is used for imaging and calibration. By referring to the figure from Fig. 6A and Fig. 6B, the controller may determine the flow with the lowest parasitic loss for a given CAC coolant temperature (CACCT), as measured at the outlet of the low-temperature heat exchanger. The controller may use curve 602 and a function of the CACCT, the ideal / desired AC head pressure (ACPRES_ideal), and a desired / ideal coolant flow for coolant flow control. The estimated lowest parasitic losses may be set as the base flow rate through the AC loop for open-loop control. A corresponding AC head pressure for the given CACCT may also be determined from the figure and used as a reference pressure for closed-loop control of the coolant flow through the AC loop. A gain term, Kp, may then be determined based on an error between the measured actual AC head pressure and the reference / expected AC head pressure.The gain term and error can be used for a closed-loop correction of the coolant flow rate through the AC loop.

[0045] In one example, the activation of the open-loop control of the coolant flow through the AC loop may be triggered in response to the AC being turned on and / or a request for cabin cooling being received. In response to the air conditioning demand, the controller may measure the coolant temperature available in the low-temperature coolant loop for the AC condenser. The controller may then look up the desired optimal coolant flow rate based on the measured temperature at which fuel economy losses are minimal, such as by invoking the Fig. out of Fig. 6A. Otherwise, if there is no air conditioning demand, the controller can turn off open-loop control of the coolant flow through the AC loop. In doing so, the controller can determine the coolant temperature available in the low-temperature coolant loop for the AC condenser and then look up a desired coolant flow rate with the AC off to establish the preconditions for the next AC turn-on. These loops can then run continuously to improve AC efficiency. By maintaining a low (lower threshold) coolant flow even when the AC system is not in use, the AC condenser can be temperature-prepared for the next demand request.Similarly, by maintaining a low (lower threshold) refrigerant flow even when the AC system is not in use, during start / stop conditions where the residual AC pressure decreases, the AC can be prepared in terms of pressure and temperature for the next engine start and compressor start.

[0046] At 406, based on the desired coolant flow through each component, a power of the electric coolant pump may be adjusted in coordination with a position of the proportional valve. As described with reference to Fig. 5, the pump and proportional valve may be controlled based on the CAC temperature and AC head pressure to meet cooling demands. For example, if there is an increase in driver demand torque and boost pressure (such as during vehicle acceleration), it may be determined that CAC cooling needs to be prioritized, and the pump output may be adjusted to provide a desired coolant flow rate while the proportional valve is adjusted to supply an amount of coolant to the CAC loop. As another example, if cabin cooling demand increases, it may be determined that AC cooling needs to be prioritized, and the pump output may be adjusted to provide a desired coolant flow rate while the proportional valve is adjusted to supply an amount of coolant to the AC loop.In still other examples, as transmission oil temperature (TOT) increases, it may be determined that TOC cooling needs to be prioritized, and pump power may be adjusted to provide a desired coolant flow rate while the proportional valve is adjusted to supply an amount of coolant to the TOC loop.

[0047] At 408, an expected AC head pressure may be modeled based on the coolant flow through the AC loop. Specifically, the AC head pressure may be determined as a function of the CACCT (temperature of the coolant from the low-temperature automotive radiator), the coolant flow through the CAC, and the engine power. As an example, the controller may refer to a 3D map, such as the example map shown in Fig. 6A to model the expected AC head pressure. As used herein, AC head pressure refers to the pressure of the AC system downstream of the AC compressor and upstream of the expansion valve, i.e., on the high-pressure side of the AC system. The present inventors have recognized that AC head pressure is more responsive to thermal loading on the AC condenser than AC temperature, and particularly evaporator temperature. By using AC head pressure to determine refrigerant flow, refrigerant flow can be changed more quickly in response to changes in cooling demand.

[0048] Fig. Figures 6A-6B show mapping data at a series of steady-state points from which the optimal baseline operating value for steady-state refrigerant flow and expected AC head pressure can be determined as a reference. These are then compared to the actual AC head pressure to derive how intensively the system is operating (i.e., the coefficient of performance, or COP). This parameter is used as an indication for correcting the refrigerant flow rate. In particular, as the difference between the actual and expected AC head pressure increases, and therefore the COP increases, a larger correction to the refrigerant flow rate is required to return the system to the optimal / most efficient point more quickly. The COP is negatively affected by increased AC head pressure, indicating that the compression work is increased for a given cooling load.In addition, the COP is negatively influenced by parasitic losses in the coolant pump (thus an optimal steady-state flow).

[0049] Additionally, using the same AC head pressure for AC clutch control improves AC performance. Specifically, if the AC head pressure is above a (normal) threshold range, but the AC compressor is not at risk due to the higher pressure, the AC clutch is kept engaged and the refrigerant flow is increased to the maximum amount the pump can deliver. However, if the refrigerant flow is still not high enough and the AC head pressure continues to increase to the point where condenser damage may occur, the AC clutch is opened.

[0050] The Fig. represents a 3D Fig. the change in AC head pressure with the coolant flow (in gpm) and the coolant temperature in the charge air cooler (CACCT). As the coolant temperature (in the low-temperature circuit) increases, the AC head pressure increases. Furthermore, as the coolant flow rate increases, the AC head pressure decreases. At a constant coolant temperature, the AC head pressure approaches an asymptote (see also Fig. 6B). Thus, a large increase in refrigerant flow rate results in a small reduction in AC head pressure. Parasitic losses can be determined as the sum of the AC compressor losses and the refrigerant pump losses in watts. As the refrigerant flow increases, the parasitic losses decrease and then increase. The minimum parasitic AC pump loss occurs at a refrigerant temperature determined using the Fig. can be depicted.

[0051] For example, the CACCT is measured, and the corresponding optimal coolant flow rate and expected AC head pressure are derived from two separate but coordinated functions of the CACCT. These functions are included in the control system and Fig. 6A-6B are used to fill these functions: AC_Pressure_Ref=2D_Table(CACCT_Coolant_Temperature); Base_AC_CoolantFlow=2D_Table(CACCT_CoolantTemperature).

[0052] With further reference to Fig. 4, it may be determined at 410 whether the actual AC head pressure is at a threshold or within a threshold range of the expected AC pressure. If so, then the method includes continuously adjusting each of the proportional valve positions and the electric coolant pump power at 412 as the flow demand through each loop changes.

[0053] If not, the method includes determining at 414 whether the actual head pressure is less than the expected pressure. If so, then at 416, an AC system degradation may be diagnosed based on the actual AC pressure relative to the expected pressure. As described with reference to Fig. 7, an engine control unit may diagnose a cause of the pressure drop and distinguish between a pressure drop caused by component degradation (such as AC condenser pump degradation), refrigerant loss from the AC system, and the presence of a disconnected line. At 418, a coolant flow rate and a proportion of coolant flow through the AC may be updated based on the indication of the AC system degradation.

[0054] If the actual head pressure is higher than the expected pressure, the controller can infer AC system load at 420. For example, it can determine that AC efficiency has dropped and that the AC condenser is operating more thermodynamically intensively than required, for example, due to fluctuations in engine compartment temperature. In particular, airflow through the radiator and in the engine compartment is reduced when the vehicle is stopped. This causes the temperature of all engine compartment components to gradually increase, including the coolant and refrigerant. This results in a need for increased coolant flow to achieve the same cooling function that could be achieved with less coolant at higher vehicle speeds (e.g., at 20 mph). Accordingly, based on the AC system load indication, a coolant flow rate and a proportion of coolant flow through the AC can be updated.For example, the pump power can be reduced and the coolant flow through the AC can be increased to lower the AC head pressure. Then the routine ends.

[0055] In one example, the controller may use an "inverse" hydraulic model that considers desired flow rates and determines device settings accordingly. The hydraulic approach can account for branch resistance and viscosity. Essentially, the 3-way proportional valve is adjusted based on the flow allocation in the branches. After accounting for the effects of branch resistance, the flow is summed and used to determine the pump command. Both the pump and valve can undergo "hardware characteristic compensation" to account for hardware changes. The two continuously variable flow devices (the electric pump and the 3-way proportional valve) are adjusted to precisely meet the branch flow requests and maintain a minimum flow in the parallel branch.This results in the electric pump operating at the minimum pump setting and with minimized parasitic losses, while still meeting the required cooling requirements. By adding multiple functions, a single model (described below) can be calibrated to accommodate a variety of hydraulic configurations.

[0056] As mentioned with reference to Fig. As discussed in Figure 2, the low-temperature loop of the coolant system includes at least three devices that require coolant flow: the charge air cooler, the water-cooled AC condenser, and the transmission oil cooler. The circuit includes two continuously variable actuators, the pump, and the 3-way (diverter / proportional) valve. The transmission oil cooler itself includes an on / off switch. The hydraulic circuit separates valve-controlled coolant consumers from the rest of the coolant system. While other components on the other loop could be valve-controlled, this loop is dedicated to low-temperature cooling consumers. Specifically, three different consumers share the power from the LT car radiator: the water-cooled AC condenser, the charge air cooler, and the automatic transmission cooler (or warm-up unit, also referred to herein as ATWU).The consumers are arranged parallel to each other but in series with the coolant pump and the radiator. The valve-controlled consumers are grouped into the valve-controlled path. Each branch is then assumed to have a smaller imaginary pump to provide the flow to that branch. By combining the flows of the imaginary pumps, the actual desired setting of a single large pump can be achieved. Conceptually, the total flow requirement for the valve-controlled path is provided using the (large) imaginary pump, while the valve is used to allocate the flow between the devices grouped in the control path. Thus, the valve controls the flow distribution between the CAC and the AC, and then a check is performed by the controller to ensure that the minimum TOC flow rate is met. The TOC flow rate is then controlled by the pump.

[0057] In the approach discussed, the analogy to electrical circuits is used to analyze the coolant system. The pump is considered equivalent to a voltage source, which is true for impeller pumps such as those in the coolant system. The flow in the individual branches is considered equivalent to a current, I (.) , considered (and so designated), and the flow resistances in the individual devices are given by R (.) The subscripts indicate the name of the consumer or device (where "rad" refers to the LT car radiator, "cac" refers to the charge air cooler, "pump" refers to the electric coolant pump, "atwu" refers to the transmission oil cooler, and "cond" refers to the AC condenser). Applying the voltage and current laws, we obtain the following equations: V=Ipump(Rrad+Rpump)+IatwuRatwu V=Ipump(Rrad+Rpump)+IcacRcac V=Ipump(Rrad+Rpump)+IcondRcond Ipump=Iatwu+Icac+Icond

[0058] The above equations can then be used to eliminate the current in the ATWU and the pump flow rate. The resulting relationships are as follows: Iatwu=Icac+Icond1Rcac+1Rcond1Ratwu Icac=Icac+Icond1Rcac+1Rcond1RcacIcond=Icac+Icond1Rcac+1Rcond1Rcond Ipump=Icac+Icond1Rcac+1Rcond(1Rcac+1Rcond+1Ratwu) V=Icac+Icond1Rcac+1Rcond(1Rcac+1Rcond+1Ratwu)(11Rcac+1Rcond+1Ratwu+Rrad+Rpump)

[0059] The resistances in the two branches of the valve-controlled path are not independent, but rather depend primarily on the valve position, and v, taking into account the nonlinearities of the system, these resistances could possibly also depend on the flow rates in the two branches. For the most general case, the resistances can be characterized as follows: 1Rcac1Rcac+1Rcond=fv{uv,Icac,Icond}, 1Rcac+1Rcond=1Rv,eq=fv,Req{uv,Icac,Icond}.

[0060] Equation (4) refers to the flow fraction through the CAC branch (or the priority branch) and the second equation refers to the equivalent resistance of the valve-controlled path, R v,eq .

[0061] To relate the resistances to the flow through each branch, we define the fraction of flow through the valve that flows through one of the branches. This fraction is also related to the flow resistances of the two branches. The relationship for the fraction of flow through the CAC is given by: xv=IcacIcac+Icond=1Rcac1Rcac+1Rcond

[0062] The pump potential, V, depends on the input pump speed, u p , and the flow resistance of the circuit. One can imagine that the pump potential or flow rate for a given speed is a result of the intersection of the curves for pump characteristics and the flow resistance of the circuit. Ipump=V(11Rcac+1Rcond+1Ratwu+Rrad+Rpump)=fpump{up,(11Rcac+1Rcond+1Ratwu+Rrad+Rpump)}

[0063] The tax inputs, u p and u v , can be determined using equations (1) to (4) if the following are known: 1. Requested values ​​for I cac and I cond 2. Relationship between the flow rate and the valve position f v {u p , I cac , I cond} 3. Equivalent resistance of the valve-controlled path f v,Req {uv , I cac , I cond} 4. Resistance in the ATWU Way 5. Resistances in the pump and car cooler parts of the circuit are known 6. Resolved relationship between the properties and the flow resistance f pump of the cycle

[0064] In a first case, related to the pump, the equivalent resistances can be independent of the valve position, that is, f v,Req {u v , I cac , I cond} = R v,eq be a constant. By reformulating the problem of controlling flows into the CAC and COND branches as controlling the total flow through the valve-controlled branches I cac + I cond = I v,total we get the following: up=fpump−1{Iv,totalRv,eq(1Rv,eq+1Ratwu),(11Rv,eq+1Ratwu+Rrad+Rpump)}

[0065] In a second case, which refers to the valve, the resistances in the individual branches do not depend on the absolute values ​​of I cac and I cond from. f v {u v , I cac , I cac} = f v {u v}. uv=f¯v−1{IcacIcac+Icond}

[0066] In the present scenario, there is a parallel path that influences the relationship between the pump flow and the flow through the valve-controlled circuit. Based on equation (2), there is a relationship between the total flow through the valve-controlled path and the pump flow. Using the equivalent resistance and the total valve flow variable, we can simplify the equation as follows: Ipump=Iv,total1Rv,eq(1Rv,eq+1Ratwu)

[0067] If the transmission cooler circuit is closed, there is no air flow through the ATWU branch and therefore I pump = I v,total . Therefore, the resulting relationship between the pump command and the total flow through the valve is given by: up=fpump−1{Iv,total,(Rv,eq+Rrad+Rpump)}

[0068] Therefore, opening or closing the ATWU portion of the circuit affects the overall resistance of the circuit and thus the relationship between the flow through the 3-way valve and the pump command.

[0069] In an example of a restricted condition, the total valve flow requested may exceed the flow available at the branch. This may occur if the requested flow is such that the pump cannot reach its maximum value upmax=1 is commanded, but the flow at the valve is below the total flow requirement. Alternatively, this can occur if the value commanded to the pump is limited by a consumer / device other than the valve-controlled path. It may be the case that (upmax<1).

[0070] If the pump is on up* is specified, then the expected flow through the valve can be characterized using equation (5) and the relationship between pump and valve flow rates as follows: Iv,totalmax=1Rv,eq(1Rv,eq+1Ratwu)fpump{upmax,(11Rv,eq+1Ratwu+Rrad+Rpump)}

[0071] In this scenario, the priority consumer's demands are met, while the remaining flow is diverted to the other consumer. This is addressed by defining a new term as the revised condenser flow (flow through the non-priority path). The expected flow through the branch is given by: Iv,totalexp=min{Iv,totalmax,Iv,total}

[0072] In this scenario, the priority consumer's demands are met, while the remaining flow is diverted to the other consumer. The resulting revised condenser flow (flow through the non-priority path) would then be: Icond,rev=Iv,totalexp−Icac l˜cac=IcacIv,totalexp I˜cond=icond,revIv,totalexp uv=f¯v−1{l˜cacIv,totalexp}

[0073] In another example of a restricted condition, the total valve flow requested may be less than the flow available at the branch. This may be due to the requested flow being such that the pump cannot operate at its minimum value. rpm is commanded, but the flow at the valve exceeds the total flow demand. Alternatively, this can occur if the minimum value commanded to the pump is determined by a consumer / device other than the valve-controlled path.

[0074] For example, if the ATWU has a certain minimum flow rate, Iatwumin, requests, an ATWU branch with minimum demanded flow can be translated into minimum total flow through the valve-controlled path using the above equation. The total flow in the valve-controlled path is related to the ATWU by the following relationship. Iv,totalmin=IatwuminRatwuRv,eq

[0075] Or if a certain minimum value is imposed on the pump command: Iv,totalmin=1Rv,eq(1Rv,eq+1Ratwu)fpump{upmin,(11Rv,eq+1Ratwu+Rrad+Rpump)}

[0076] If this minimum flow request is greater than the total flow, then the demands of both paths cannot be met simultaneously. Again, in this case, the valve is set to divert the excess flow to the non-priority path. Iv,totalexp=max{Iv,totalmin,Iv,total} Icac,rev=Icac Icond,rev=Iv,totalexp−Icac l˜cac=Icac,revIv,totalexp l˜cond=Icond,revIv,totalexp uv=f¯v−1{l˜caclv,totalexp}

[0077] In another example of a restricted condition, the pump command may be fixed. Then, the commanded value may be determined by a consumer / device other than the valve-controlled path. In this case, the following applies: Iv,totalexp=1Rv,eq(1Rv,eq+1Ratwu)fpump{up*(11Rv,eq+1Ratwu+Rrad+Rpump)} Icac,rev=Icac Icond,rev=Iv,totalexp−Icac l˜cac=Icac,revIv,totalexp l˜cond=Icond,revIv,totalexp uv=f¯v−1{l˜cacIv,totalexp}

[0078] If there is a change in the priority of the loads in the valve-controlled path, the calculation can be reversed, with the CAC value being recalculated if the priority changes. For example, if AC has priority, then: Icac,rev=Iv,totalexp−Icond Icond,rev=Icond l˜cac=Icac,revIv,totalexp l˜cond=Icond,revIv,totalexp uv=f¯v−1{l˜cacIv,totalexp}

[0079] In one example, this can be implemented as a 2D lookup table, where the table provides the valve setting. The table can utilize the full capability of the memory available in the controller. The expected total flow can be used as input to compensate for nonlinear valve behavior. The implementation can be hard-coded for a 3-way valve.

[0080] The inputs to the calculation can include requested values ​​for the coolant flow through the CAC and AC loops. If I_cac and I_cond are normalized flow variables, then they should be normalized by the same number, for example, the maximum flow through the valve. The controller can also obtain TOC settings (which affect the flow resistance in the path not controlled by the valve). The controller can further obtain the mapping between pump flow and flow through the valve-controlled path. The pump command is then determined using the above equations from the total flow through the pump and the resistances in the individual branches. The total flow at the valve is then mapped to the pump flow. The lookup table can be used if the relationship is significantly nonlinear.The valve position can be used as input if there is a significant interaction that might require a numerical iterative solution. The tables can be calibrated based on ATWU settings.

[0081] Now, with reference to Fig. 5 shows an exemplary routine 500 for dividing coolant flow through the various components of a coolant system based on cooling demand. The method allows different cooling demands to be met while prioritizing certain cooling demands over others during selected conditions. This may be necessary when individual loops have conflicting cooling requirements or the current cooling requirements for individual loops cannot be met due to capacity constraints.

[0082] At 502, the method includes determining component-specific flow requirements. For example, an amount of cooling required at each of the AC loop, the CAC loop, and the TOC loop may be determined based on parameters such as MAF, MCT, TCT, CACCT, driver cooling demand, and estimates of ambient temperature and humidity. As another example, the AC demand may depend on cabin cooling needs, while the CAC demand may depend on the temperature of the air entering the charge air cooler. Additionally, the CAC demand may vary as driver demand varies, with the CAC demand increasing as driver demand increases and boost pressure is requested. Increased operation of the intake compressor results in a warmer charge entering the CAC.Determining the cooling requirements may include determining a coolant flow rate, a desired coolant pressure at the component, and a desired temperature change at each component. At 504, component-specific coolant flow rates may be determined based on the component-specific cooling requirements and the component-specific flow requirements.

[0083] At 506, the coolant flow required by the TOC may be updated based on the torque converter slip schedule. As described with reference to Fig. 8, during conditions where the torque converter (TC) is slipping and generating excessive heat, the transmission fluid temperature at the TC outlet may be higher than the transmission fluid temperature at the oil pan. During these conditions, the coolant flow through the TOC may be adjusted based on a derived TC temperature rather than the TOT estimated at the oil pan to reduce the likelihood of underestimating the temperature and providing insufficient coolant flow. Thus, if the transmission fluid temperature is underestimated, coolant boiling may occur.For example, the coolant flow may be determined based on a transmission oil temperature including an estimated transmission oil temperature estimated via a temperature sensor coupled to an oil pan when the transmission torque converter slip is below a threshold, wherein the transmission oil temperature includes a derived transmission oil temperature modeled based on the torque converter slip when the transmission torque converter slip is above the threshold.

[0084] At 507, a pump command for the electric coolant pump may be determined based on the component-specific flow requirements. For example, a pump command may be determined via a flow model, as detailed here, that provides the combined flow requirement for each of the components. In one example, a pump setting may be determined as the maximum of the TOC flow requirement and the CAC and AC condenser flow requirements.

[0085] At 508, it may be determined whether coolant flow to the CAC needs to be prioritized (also referred to herein as CAC priority). In one example, the CAC may need to be prioritized in response to an AC cooling demand below the threshold (e.g., when no AC cooling is requested) or an AC head pressure below the threshold alongside an MCT above the threshold (resulting from insufficient CAC cooling and increased driver demand). If so, then at 510, the method includes adjusting the proportional valve to flow coolant through the AC at a minimum flow rate while flowing coolant through the CAC at a maximum flow rate. Additionally, a power of the pump may be increased.

[0086] If the CAC priority is not confirmed, at 512 it may be determined whether coolant flow to the AC needs to be prioritized (also referred to herein as AC priority). In one example, the AC may need to be prioritized in response to a below-threshold MCT (resulting from CAC cooling) or a below-threshold CAC cooling demand (e.g., when no CAC cooling is requested) in addition to a high AC head pressure. These conditions may indicate a need for additional AC cooling. If so, then at 514 the method includes adjusting the proportional valve to flow coolant through the CAC at a minimum flow rate while flowing coolant through the AC at a maximum flow rate. Additionally, a power of the pump may be increased.

[0087] If neither AC priority nor CAC priority is asserted, but both have a cooling demand, then at 516 the method includes adjusting a position of the proportional valve to distribute pump output between the various loops and sub-loops of the coolant system to provide component-specific flow rates. For example, under extreme cooling loads, such as when the vehicle is towing uphill in desert conditions, there may not be sufficient cooling to operate the AC system either efficiently or at maximum capacity while providing adequate cooling at optimal engine performance. At this point, a trade-off is calibrated. The trade-off may be predetermined and stored in the controller's memory.For example, the calibrated compromise may involve directing 45% of the coolant flow to the CAC and the remaining 55% of the coolant flow to the AC loop. This provides flow modulation that meets all minimum flow requirements.

[0088] Now, with reference to Fig. 7 illustrates an exemplary method 700 for diagnosing AC system degradation based on the actual AC head pressure relative to the expected / modeled AC head pressure (such as using the map of Fig. 6). In an example, the procedure can be Fig. 7 as part of the procedure Fig. 4, such as at 416. The method allows a drop in AC pressure due to a drop in refrigerant level to be better distinguished from a disconnected refrigerant line.

[0089] At 702, the method includes confirming that the (measured) actual AC head pressure is less than an expected (modeled) pressure. The expected pressure is a pressure based on the current CAC coolant temperature of the system. In some examples, in addition to confirming that the AC head pressure is less than the expected pressure, it may be confirmed that the actual pressure remains below the expected pressure for a duration. If not, then at 704 it may be confirmed that the actual head pressure is higher than the expected pressure given the existing CAC coolant temperature of the system. Additionally, one or more thresholds may be set. In some examples, if the pressure is not close to the reference pressure (e.g., within a threshold distance of the threshold pressure), preemptive control actions may be taken.

[0090] At 706, in response to the actual head pressure being higher than the expected pressure, it may be inferred that AC system loading is present due to increased cabin cooling load. For example, it may be determined that the AC system is operating more intensively than expected due to higher cabin temperatures, such as due to higher load from the sun (or higher ambient temperatures). Accordingly, in response to the indication of AC system loading, coolant flow through the AC loop may be increased by requesting more branch flow to the AC loop and coordinating pump power and valve position to deliver the requested branch flow rate. For example, the power of the electric coolant pump and a position of the proportional valve may be adjusted using the inverse hydraulic model.In one example, the controller may provide the requested increase in coolant flow by increasing pump power by a larger amount and increasing coolant flow through the AC loop by a smaller amount. Alternatively, the controller may provide the same requested increase in coolant flow by increasing pump power by a smaller amount and increasing coolant flow through the AC loop by a larger amount. The controller may compare the fuel economy and time to improve AC head pressure between the two options and select a combination accordingly. The selection may also factor in the resulting change in CAC flow relative to the CAC coolant flow demand.

[0091] Referring again to 702, if the actual head pressure is less than expected, at 707 the error between the actual AC head pressure and the expected pressure may be integrated over the duration. In one example, the duration corresponds to a significant portion of a drive cycle, such as approximately 700 seconds. At 708, it may be determined if the actual CAC coolant temperature is within an expected range. If so, then it may be determined that the AC system is not degraded, and the routine may end. Alternatively, if the CACCT is within the range, it may be inferred that there may be an issue with the AC condenser, and if the CACCT is outside the range, then this may explain the poor system behavior.

[0092] If the actual CAC coolant temperature is outside the expected range given the existing CAC coolant temperature of the system, then at 710 it may be determined whether the integrated error is above a first threshold error (Threshold_1). If the coolant temperature is outside the expected range and the integrated error is above the first threshold error, then at 712 AC system degradation may be indicated. In particular, it may be indicated that the heat exchanger function of the AC system (e.g., at the condenser) is degraded, for example, due to a disconnected line. Additionally, at 714, in response to the disconnected line indication, the coolant flow through the AC loop may be decreased while the coolant flow through the CAC loop may be correspondingly increased, without any significant CAC impact other than subcooling.

[0093] If the actual CAC coolant temperature is outside the expected range given the existing system CAC coolant temperature and the integrated error is not above the first threshold error, then at 717, a determination may be made as to whether the integrated error is above a second threshold error (Threshold_2) that is less than the first threshold error (Threshold_1). If not, then the routine returns to 709 to indicate no AC system degradation, and the routine ends. Otherwise, if the actual CAC coolant temperature is outside the expected range given the existing system CAC coolant temperature and the integrated error is above the second threshold error (but below the first threshold error), then at 718, an indication may be given as to AC system degradation due to low refrigerant levels.For example, the low refrigerant level may be due to the presence of a leak, such as due to loose fittings. At 720, in response to the low refrigerant level indication, the coolant flow through the AC loop may be increased while maintaining the coolant flow through the CAC loop to provide AC performance even though the AC system is determined to be degraded. In particular, the coolant flow is reduced to conserve pump electrical energy. Because the AC system is determined to be degraded, cooling by the AC has no effect from the reduced pump performance. In particular, the AC performance is not adversely affected by reduced pump performance.

[0094] Now, with reference to Fig. 8 shows an exemplary method 800 for adjusting the coolant flow through a TOC. The method improves transmission oil cooling and reduces the likelihood of coolant boiling. In one example, the method may be Fig. 8 as part of the procedure Fig. 5, such as 506.

[0095] At 802, it may be determined whether the conditions for generating excess heat at the torque converter are met. Accordingly, the torque converter (TC) is a viscous coupling device that exchanges fluid inertia to transfer torque between the engine and the transmission. Consequently, it may generate significant amounts of heat. During select conditions, such as when braking torque is applied to the engine (i.e., both a brake pedal and an accelerator pedal are applied simultaneously by a vehicle operator) or when the vehicle is climbing a grade at little to no vehicle speed (with the grade being counteracted due to the driver's accelerator pedal being applied), the TC may slip and be unable to lock up due to a lack of speed. During these conditions, the temperature of the oil exiting the TC may be significantly higher than the oil at the oil pan.In particular, the oil entering the TOC may be significantly warmer than the temperature at the oil pan due to the long time constant associated with the entire mass of the transmission. If the coolant flow through the TOC is adjusted based on the TOT estimated at the oil pan, the delivered coolant flow may be less than the required coolant flow, resulting in coolant boilover. In addition to affecting the transmission, coolant boilover can also affect all engine components that share coolant with the transmission via the coolant loop, such as the AC system, intercooler, cylinder head, etc.

[0096] If TC slip / heat generation conditions are confirmed, at 804, the transmission oil temperature at the TC output may be derived. For example, the TC output temperature may be derived based on the transmission oil pan temperature and recent transmission history. Further, the TC output temperature may be determined based on the torque converter slip ratio (output speed relative to TC input speed). Additionally, at 806, the allocation of coolant flow through the TOC (relative to the AC and CAC) may be adjusted based on the TC output temperature. The allocation may further be adjusted based on a slip ratio at the TC and an engine speed. Since the TOC is parallel to the branches allocated to the AC and CAC, the maximum flow rate may be set to be the greater of the flow to the TOC branch or the sum of the AC and CAC branches.

[0097] If TC slip / heat generation conditions are not confirmed, at 808, the transmission oil temperature at the oil pan may be inferred and / or estimated and / or measured. For example, the TOT at the oil pan may be measured by a temperature sensor coupled to the oil pan. Additionally, at 810, the allocation of coolant flow through the TOC (relative to the AC and CAC) may be adjusted based on the oil pan temperature. As an example, the vehicle may be stopped because the brake is being applied (applying braking torque), or the vehicle may be on an incline, or towing a larger trailer, or there may be another condition due to which the vehicle is otherwise experiencing resistance.While the vehicle is experiencing drag, the driver may request significant torque or power, and the transmission torque converter may be open, so essentially all of the engine's power is generating heat. During these conditions, the CAC cooling load may be low and the AC cooling load may be low, but transmission cooling may be high (e.g., higher than a threshold, such as critically high). During these conditions, full pump cooling may be required. While full pump cooling may result in overcooling of the AC and CAC with little penalty in fuel efficiency, such penalty may be acceptable to provide the requested transmission cooling. In this way, by adjusting coolant distribution through a TOC based on torque converter conditions, including a TC slip ratio, coolant boiling may be better averted.

[0098] Now, with reference to Fig. Figures 9-12 show example settings for the flow of coolant through various components of an engine coolant loop during different operating modes of the coolant system.

[0099] With reference to Fig. 9 initially represents Fig. an exemplary transition from a condensation control mode of coolant system operation to a continuous control mode of coolant system operation. Fig. represents the setting of the proportional valve at trace 902, the coolant pump power at trace 904, the coolant flow through the CAC loop (CAC_Flow) at trace 906, the coolant flow through the AC loop (AC_Flow) at trace 908, the coolant flow through the TOC (TOC_Flow) at trace 910 and the cabin cooling demand at trace 912. All traces are plotted against time.

[0100] Before t1, the coolant system operates in condensation control mode in response to certain intake air conditions, such as high humidity, where condensation can form if the intake air is subcooled in the CAC. To reduce side effects such as water buildup and potential problems due to hardware damage, condensation control mode is used to minimize coolant flow to the CAC. It adjusts the pump power and valve timing based on the higher cabin cooling demand and the lower CAC cooling demand. In the illustrated example, the desired coolant flow rate is provided by operating the coolant pump at a lower power while setting the valve opening to 100%, thus directing a large portion of the coolant flow through the AC loop.

[0101] At t1, the coolant system transitions to continuous control mode in response to the elimination of conditions for condensation. In this mode, the pump capacity and valve timing are adjusted based on the increase in CAC cooling demand while maintaining the same cabin cooling demand. Specifically, the pump capacity is gradually increased while the valve timing is gradually (here, stepwise) decreased so that a calibrated proportion of the coolant flow passes through the AC loop and a remaining coolant flow passes through the CAC loop. In one example, the valve timing is decreased from 100% to 45%. In this way, flow is diverted to both the CAC (e.g., 45%) and the AC (e.g., 55%). In an alternative example, the calibrated ratio may include 35% of the flow to the CAC and 65% of the flow to the AC.Still other calibrated ratios may be possible based on the vehicle make and model or the coolant system configuration. In another example, the positions and commands may be determined based on all component flow requirements and the inverse flow model described above.

[0102] Now, with reference to Fig. 10 Fig. an exemplary transition from an extreme distribution mode to a priority AC mode of coolant system operation. Fig. represents the setting of the proportional valve at trace 1002, the coolant pump power at trace 1004, the coolant flow through the CAC loop (CAC_Flow) at trace 1006, the coolant flow through the AC loop (AC_Flow) at trace 1008 and the cabin cooling demand at trace 1010. All traces are plotted against time.

[0103] Before t11, the coolant system operates in Extreme Distribution Mode in response to cooling being requested in both the AC and CAC loops. In this mode, the pump capacity and valve setting are adjusted to provide a calibrated ratio of coolant flow through both the AC and CAC loops. In the illustrated example, the calibrated ratio includes a valve setting of 45% opening, which provides 45% of the coolant flow through the CAC loop and 55% of the coolant flow through the AC loop. Furthermore, in Extreme Distribution Mode, the pump capacity is set to 100% (maximum capacity). The valve position of 100% refers to 100% flow to the CAC.

[0104] At t11, in response to an increase in cabin cooling demand, the coolant system transitions to Priority AC mode to prioritize coolant flow to the AC loop. Using the inverse model, the pump and valve settings are adjusted to provide the desired coolant flow through the AC loop. Specifically, the pump duty is maintained at 100% while the valve setting is decreased, in the illustrated example from 45% to 20%, so that a larger proportion of the coolant flow is directed through the AC loop and a smaller remaining coolant flow is directed through the CAC loop. In this way, the cabin cooling demand can be met by the load. Referring now to Fig. 11 Fig. an exemplary transition from the extreme distribution mode to a priority CAC mode of coolant system operation. Fig. represents the engine speed at trace 1101, the setting of the proportional valve at trace 1102, the coolant pump power at trace 1104, the coolant flow through the CAC loop (CAC_Flow) at trace 1106, the coolant flow through the AC loop (AC_Flow) at trace 1108 and the coolant flow through the TOC (TOC_Flow) at trace 1110. All traces are plotted against time.

[0105] Before t21, the coolant system operates in Extreme Distribution mode in response to high cooling demand in both the AC and CAC loops. In Extreme Distribution mode, the pump capacity and valve timing are adjusted to provide a calibrated ratio of coolant flow through both the AC and CAC loops. In the example shown, the calibrated ratio includes a valve setting with 45% opening, which provides 45% of the coolant flow through the CAC loop and 55% of the coolant flow through the AC loop. Furthermore, in Extreme Distribution mode, the pump capacity is set to 100% (maximum capacity).

[0106] At t21, the coolant system transitions to Priority CAC mode in response to an increase in engine speed to prioritize coolant flow to the CAC loop. Here, 100% flow indicates a priority of coolant flow to the CAC. The increase in engine speed may occur in response to an increased demand for boost pressure, such as due to vehicle acceleration, a pedal application event, or an increase in driver demand torque. Using the inverse model, the pump and valve settings are adjusted to provide the desired coolant flow through the CAC loop. Specifically, the pump duty is maintained at 100% while the valve setting is increased, in the illustrated example from 45% to 100%, so that a larger portion of the coolant flow is directed through the CAC loop and a smaller remaining coolant flow is directed through the AC loop.In this way, the cooling requirements of the compressed intake air flowing through the CAC can be met.

[0107] With reference to Fig. 12 initially represents Fig. an exemplary transition from a continuous control mode of coolant system operation to the extreme distribution mode of coolant system operation. Fig. represents the setting of the proportional valve at trace 1202, the coolant pump power at trace 1204, the coolant flow through the CAC loop (CAC_Flow) at trace 1206, the coolant flow through the AC loop (AC_Flow) at trace 1208, the coolant flow through the TOC (TOC_Flow) at trace 1210, the cabin cooling demand at trace 1212, and the engine speed at trace 1214. All traces are plotted against time.

[0108] Prior to t31, the coolant system is operated in the continuous control mode in response to below-maximum cooling demand in both the AC and CAC loops and varying engine operating conditions. Therein, the pump power and valve timing are adjusted based on the varying cabin cooling demand and CAC cooling demand, where during some conditions the CAC cooling demand may increase while the AC cooling demand decreases, during other conditions the CAC cooling demand may decrease while the AC cooling demand increases, and during still other conditions both the CAC cooling demand and the AC cooling demand may increase or decrease (while remaining below maximum limits). In the illustrated example, the desired coolant flow rate is achieved by operating the coolant pump at a continuously varying power (such as at or around 45%, e.g.,between 25% and 45%) with equally continuous variation of the valve setting (such as at or around 45%, e.g. between 25% and 45%).

[0109] At t31, the coolant system transitions to extreme distribution mode in response to an increase in both cabin cooling demand and engine speed. The increase in engine speed may occur in response to an increased demand for boost pressure, such as due to vehicle acceleration, a pedal application event, or an increase in driver demand torque. The increase in cabin cooling demand may occur in response to an increase in ambient temperature. Specifically, in response to the increase in both CAC and AC cooling demand, the pump duty is increased while the valve timing is also changed and fixed, for example, increased so that a predefined calibrated proportion of coolant flow passes through the AC loop. In the illustrated example, the valve timing is increased to 45% while the pump duty is increased to 100% (maximum duty).In an alternative example, the value can be lowered. In this way, both the CAC and AC condenser cooling demands are best met. In this way, coolant can flow through each of a CAC, an AC condenser, and a transmission oil cooler, with the flow divided based on cooling demands. By adjusting the flow in response to an AC head pressure (rather than a temperature), a faster response to changes in cooling demand can be provided, improving cooling response times. Additionally, changes between the actual AC head pressure and an expected head pressure can be advantageously used to better estimate AC efficiency and load. By using the same head pressure for AC clutch control, the need for additional sensors is reduced.By sharing the coolant between the various components requiring cooling, the need for additional radiators and fans is reduced, providing component reduction benefits. By adjusting coolant distribution through a TOC based on torque converter conditions, including a TC slip ratio, coolant boiling can be better prevented. Additionally, underhood space is improved. Furthermore, by improving AC cooling through the use of coolant, the AC condenser can be moved away from the front of the vehicle, reducing warranty issues.By correlating AC head pressure errors with changes in AC compressor function, AC system degradation due to compressor problems can be better differentiated from those due to low refrigerant levels, allowing appropriate remedial action to be taken. Overall, engine cooling performance for multiple components requiring cooling can be increased while improving fuel economy.

[0110] An exemplary method for operating a vehicle air conditioning system includes adjusting, via a pump and a proportional valve coupled to each of a charge air cooler and an air conditioning condenser, a flow of coolant through the condenser in which refrigerant other than the coolant flows, wherein the adjusting is performed in response to a coolant temperature in the charge air cooler and an actual head pressure of an air conditioning compressor. In the preceding example, adjusting in response to the reference head pressure additionally or optionally includes adjusting in response to a difference between the actual head pressure and a reference head pressure, wherein the flow of coolant through the condenser is increased when the actual head pressure exceeds the reference head pressure.In any or all of the preceding examples, the reference head pressure is additionally or optionally modeled via a two-dimensional map, where the map is stored as a function of coolant temperature and coolant flow rate. In any or all of the preceding examples, the actual head pressure additionally or optionally includes a pressure at a location downstream of the AC compressor and upstream of each of an expansion valve and the condenser in a refrigerant loop coupled to the AC system. In any or all of the preceding examples, the pump and the proportional valve are additionally or optionally selectively coupled to a refrigerant loop of the AC system, where each of the refrigerant loop and the refrigerant loop is coupled to the condenser.In any or all of the preceding examples, the adjusting additionally or optionally further occurs in response to a temperature of oil in a transmission cooler circuit, wherein the transmission cooler circuit is coupled to the coolant circuit at a transmission cooler, the transmission cooler being located upstream of the proportional valve and downstream of the pump, the transmission cooler further coupled to an engine coolant circuit that is different from the coolant circuit of the AC system. In any or all of the preceding examples, the adjusting additionally or optionally includes, as the temperature of the oil in the transmission cooler circuit increases, increasing a power of the pump to increase coolant flow to the condenser through the transmission cooler, wherein the increase in oil temperature occurs in response to increased torque converter slip.In any or all of the preceding examples, adjusting additionally or optionally includes, for a given cabin cooling demand, maintaining or decreasing flow through the condenser while increasing flow through the charge air cooler as the charge air temperature increases, and increasing flow through the condenser while maintaining or decreasing flow through the charge air cooler when the actual head pressure exceeds a reference head pressure. In any or all of the preceding examples, adjusting additionally or optionally includes, in response to each of the actual AC head pressure and the charge air temperature exceeding respective thresholds, increasing a power of the pump to an upper limit while setting the proportional valve to a position that provides a calibrated fixed ratio of coolant flow through the condenser relative to the charge air cooler.In any or all of the preceding examples, the adjusting additionally or optionally includes feedforwardly selecting a pump and proportional valve setting that provides a coolant flow rate determined as a function of coolant temperature in the charge air cooler, and feedforwardly adjusting the pump and proportional valve setting based on an error between the actual head pressure and a reference head pressure, wherein the reference head pressure is determined as a different function of coolant temperature.

[0111] Another example method for a vehicle includes: flowing refrigerant through a refrigerant circuit including an air conditioning (AC) condenser; flowing coolant through a first branch of a coolant circuit including the condenser and through a second branch of the coolant circuit including a charge air cooler (CAC), wherein the coolant flow through the first branch is adjusted relative to the second branch based on an AC head pressure in the refrigerant circuit, a coolant temperature in the coolant circuit, and a CAC cooling demand. In any or all of the preceding examples, the first and second branches are additionally or optionally located downstream of each of a coolant pump and a proportional valve, and wherein the first and second branches are in parallel with a transmission oil cooler.In any or all of the preceding examples, the refrigerant flow through the first branch relative to the second branch is additionally or optionally adjusted via adjustments to a pump capacity and a position of the proportional valve. In any or all of the preceding examples, the refrigerant circuit additionally or optionally includes an AC compressor, a thermal expansion valve, an AC clutch, the condenser, and an AC evaporator, and wherein the head pressure in the refrigerant circuit is based on a position of the AC clutch, a temperature of the AC condenser, a position of the thermal expansion valve, and a vehicle cabin cooling demand. In any or all of the preceding examples, the refrigerant flow through the first branch relative to the second branch is additionally or optionally further based on a transmission oil temperature of oil circulating through the transmission oil cooler.In any or all of the preceding examples, adjusting additionally or optionally includes operating with an initial setting of pump power and proportional valve position based on coolant temperature and then transitioning from the initial setting to a final setting of pump power and proportional valve position based on AC head pressure relative to a reference AC head pressure, where the reference AC head pressure is modeled as a two-dimensional function of coolant temperature, coolant flow rate, and change in CAC cooling demand.

[0112] Another example vehicle system includes: a vehicle cabin; an air conditioning (AC) system including an evaporator and a condenser for cooling cabin air; a boosted engine system including an engine and a turbocharger compressor coupled upstream of a charge air cooler (CAC); a refrigerant circuit circulating refrigerant through the condenser, the circuit including a pressure sensor; a first coolant circuit circulating coolant through each of the condenser, the CAC, and a transmission oil cooler (TOC), the first coolant circuit including an electric pump, a proportional valve, and a temperature sensor; and a second coolant circuit circulating coolant through each of the engine, an exhaust manifold cooler, and the TOC, the second coolant circuit including a mechanical pump.In any or all of the preceding examples, the refrigerant circuit is additionally or optionally coupled to the first coolant circuit at the condenser, the first coolant circuit being coupled to the second coolant circuit at the TOC, the TOC receiving oil from a torque converter output, and the condenser being coupled to a first branch of the first coolant circuit downstream of the proportional valve and the CAC being coupled to a second branch of the first coolant circuit downstream of the proportional valve, the first branch being different from and parallel to the second branch.In any or all of the preceding examples, the system additionally or optionally further comprises a controller having computer-readable instructions stored on non-transitory memory to: select an operating mode based on an AC cooling demand relative to a CAC cooling demand, wherein the AC cooling demand is based on driver-requested cabin cooling, wherein the CAC cooling demand is based on driver-requested torque; and in response to the selected operating mode, operating the pump at a power and the proportional valve determined as a function of the CAC cooling demand in the first coolant circuit and the AC head pressure in the refrigerant circuit.In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: in response to an increase in one of the AC cooling demand and the CAC cooling demand, increase the pump power toward a threshold power and set the proportional valve to a position to provide a variable ratio of coolant flow through the first branch relative to the second branch that is a function of the AC cooling demand relative to the CAC cooling demand; and in response to an increase in each of the AC cooling demand and the CAC cooling demand, increase the pump power to the threshold power and set the proportional valve to a position to provide a fixed ratio of coolant flow through the first branch relative to the second branch.

[0113] An example method of operating a vehicle air conditioning system includes: in response to each of a cabin cooling demand and a charge air cooler (CAC) cooling demand being above a threshold, adjusting, in parallel, coolant flow through each of an air conditioning (AC) condenser and a charge air cooler (CAC) of a coolant loop to meet the CAC cooling demand and cabin cooling demand, wherein the coolant flow is adjusted based on an AC head pressure and further based on a CAC charge air outlet temperature. In any or all of the preceding examples, the adjusting additionally or optionally includes adjusting the coolant flow via adjustments to a proportional valve located upstream of each of the AC condenser and the CAC cooler.In any or all of the preceding examples, adjusting additionally or optionally further includes adjusting the coolant flow rate via adjustments to a power of a coolant pump that pumps the coolant through each of the AC condenser and CAC cooler via the proportional valve. In any or all of the preceding examples, adjusting is additionally or optionally performed to maintain an AC head pressure of the AC condenser at a desired pressure. In any or all of the preceding examples, a desired coolant flow rate through the condenser is additionally or optionally modeled via a two-dimensional map stored as a function of a CAC coolant temperature and the AC head pressure.In any or all of the preceding examples, the AC condenser is additionally or optionally coupled to a refrigerant circuit including an AC compressor, an AC clutch, and a thermal expansion valve, and wherein the head pressure downstream of the AC compressor and upstream of the thermal expansion valve in the refrigerant circuit is estimated. In any or all of the preceding examples, the method additionally or optionally further comprises: in response to the AC head pressure exceeding a threshold pressure, maintaining the AC clutch engaged and increasing pump power; and in response to the AC head pressure continuing to exceed the threshold pressure after increasing pump power, disengaging the AC clutch.In any or all of the preceding examples, the pump and the proportional valve are additionally or optionally selectively coupled to the coolant circuit, and wherein each of the coolant circuit and the refrigerant circuit is coupled to the condenser. In any or all of the preceding examples, the coolant flow is additionally or optionally further adjusted in response to a temperature of oil in a transmission cooler circuit, wherein the transmission cooler circuit is coupled to the coolant circuit at a transmission cooler, the transmission cooler being located upstream of the proportional valve and downstream of the pump. In any or all of the preceding examples, the adjusting additionally or optionally includes, as the temperature of oil in the transmission cooler circuit increases, increasing a power of the pump, wherein the increase in oil temperature is in response to increased torque converter slip.

[0114] Another example method includes: during a first condition, when cooling demand at an air conditioning (AC) condenser is below a lower threshold, adjusting a power of a coolant pump and a position of a proportional valve of a coolant circuit to flow coolant through the condenser at a first, fixed flow rate while flowing coolant through a charge air cooler (CAC) at a second, variable flow rate based on the CAC cooling demand; and during a second condition, when cooling demand at the condenser is above a higher threshold, adjusting the power of the coolant pump and the position of the proportional valve to flow coolant through the CAC at a third, fixed flow rate while flowing coolant through the condenser at a fourth, variable flow rate based on the cabin cooling demand.In any or all of the preceding examples, additionally or optionally, during the second condition, the power of the coolant pump is increased to an upper limit, and wherein during the first condition, the power of the coolant pump is below the upper limit. In any or all of the preceding examples, additionally or optionally, during the first condition, the second variable flow rate is mapped as a function of the AC head pressure and the coolant temperature, and wherein during the second condition, the fourth variable flow rate is mapped as a function of the AC head pressure and the coolant temperature.In any or all of the preceding examples, the coolant circuit additionally or optionally further includes a transmission oil cooler (TOC) in parallel with the condenser and the CAC, each coupled downstream of the proportional valve to different branches of the coolant circuit, wherein the coolant circuit is coupled to a refrigerant circuit at the condenser, wherein the coolant circuit is coupled to a transmission oil circuit at the TOC, and wherein the AC head pressure is estimated at the refrigerant circuit and the coolant temperature is estimated at the coolant circuit. In any or all of the preceding examples, additionally or optionally, during the first condition, the second variable flow rate is further adjusted based on a transmission oil temperature of the TOC, and wherein during the second condition, the fourth variable flow rate is further adjusted based on the transmission oil temperature of the TOC.In any or all of the preceding examples, the transmission oil temperature is additionally or optionally an estimated temperature estimated via a temperature sensor coupled to an oil pan when torque converter slip is lower, and wherein the transmission oil temperature is a modeled temperature based on a change in torque converter temperature when torque converter slip is higher.

[0115] Another exemplary vehicle system includes: a vehicle cabin; an air conditioning (AC) system including an evaporator and condenser for cooling cabin air; a boosted engine system including an engine and a turbocharger compressor coupled upstream of a charge air cooler (CAC); a refrigerant circuit circulating refrigerant through the condenser, the circuit including a pressure sensor; a first coolant circuit circulating coolant through each of the condenser, the CAC, and a transmission oil cooler (TOC), the first coolant circuit including an electric pump, a proportional valve, and a temperature sensor; and a second coolant circuit circulating coolant through each of the engine, an exhaust manifold cooler, and the TOC, the second coolant circuit including a mechanical pump.and a controller including computer-readable instructions for: in response to a cabin cooling demand, estimating a base coolant flow rate through the condenser based on the coolant temperature; estimating a corrective coolant flow rate based on an actual AC head pressure relative to a reference AC head pressure, the reference AC head pressure determined as a function of the coolant temperature; adding the corrective coolant flow rate to the base coolant flow rate to determine a net coolant flow rate through the AC condenser;and actuating the pump and the proportional valve to provide the net coolant flow rate through the AC condenser. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: in response to no cabin cooling demand, estimating the base coolant flow rate through the condenser based on the coolant temperature relative to the ambient temperature; and actuating the pump and the proportional valve to provide the base coolant flow rate through the AC condenser. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: in response to a concurrent engine cooling demand, estimating a base coolant flow rate through the CAC based on the coolant temperature;and adjusting a power of the pump and a position of the proportional valve to provide the base coolant flow rate through the CAC while maintaining the net coolant flow rate through the AC condenser. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: in response to each of the cabin cooling demand and the engine cooling demand exceeding a threshold, increase the power of the pump to an upper limit and set the position of the proportional valve to a position that provides a fixed calibrated ratio of coolant flow through the condenser relative to the CAC, wherein the fixed calibrated ratio is independent of the AC cooling demand relative to the engine cooling demand;

[0116] An example method for a vehicle system includes: estimating a requested coolant flow rate through a coolant circuit based on a cooling demand at each of an air conditioning condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of the coolant circuit; estimating an effective flow resistance through the coolant circuit based on a position of a first valve coupled to the condenser and the CAC and a second valve coupled to the TOC; and adjusting a coolant pump power based on the estimated flow resistance to provide the requested coolant flow rate.In any or all of the preceding examples, the first valve is additionally or optionally a three-way proportional valve configured to divide coolant between a first branch of the coolant loop including the condenser and a second branch of the coolant loop including the CAC, wherein the second branch is arranged in parallel with the first branch. In any or all of the preceding examples, the second valve is additionally or optionally coupled to a third branch of the coolant loop including the TOC, wherein the third branch is parallel to and bypasses each of the first and second branches.In any or all of the preceding examples, the coolant circuit is additionally or optionally coupled to a transmission oil circuit at the TOC, wherein the transmission oil circuit includes a transmission torque converter, and wherein the coolant circuit is coupled to a refrigerant circuit of an air conditioning system at the condenser. In any or all of the preceding examples, the method additionally or optionally further comprises opening the second valve in response to a transmission torque converter slip ratio above a threshold and closing the second valve in response to a transmission torque converter slip ratio below a threshold, wherein the effective flow resistance through the coolant circuit is greater when the second valve is closed and the effective flow resistance is less when the second valve is open.In any or all of the preceding examples, estimating the requested coolant flow rate additionally or optionally includes mapping the coolant flow rate as a function of the coolant temperature at an outlet of a low-temperature automotive radiator and an AC head pressure in the refrigerant circuit. In any or all of the preceding examples, adjusting the coolant pump power additionally or optionally includes adjusting the coolant pump power between a lower threshold and a higher threshold, wherein the lower threshold allows at least some coolant flow through the condenser in the absence of a cooling demand at the condenser.In any or all of the preceding examples, the method additionally or optionally further comprises: assigning a priority status to one of the first branch and the second branch based on the cooling demand at the condenser relative to the cooling demand at the CAC. In any or all of the preceding examples, the method additionally or optionally further comprises, when the coolant pump power is at the lower threshold, adjusting the first valve to provide a coolant flow that meets the cooling demand of one of the first branch and the second branch having a higher priority status, while diverting excess coolant flow to the other of the first branch and the second branch having a lower priority status.In any or all of the preceding examples, the method additionally or optionally further comprises, when the coolant pump power is at the higher threshold, adjusting the first valve to provide a coolant flow that meets the cooling demand of one of the first branch and the second branch having a higher priority status, while diverting excess coolant flow to the other of the first branch and the second branch having a lower priority status. In any or all of the preceding examples, the method additionally or optionally further comprises, when the coolant pump power is at the higher threshold, adjusting the first valve to provide a fixed ratio of coolant flow through the first branch and the second branch when the first branch and the second branch have the same priority status.

[0117] Another exemplary method for a vehicle air conditioning (AC) system includes: estimating a cooling demand at each of the air conditioning condenser and a charge air cooler (CAC) coupled to different branches of a coolant loop; estimating a total coolant flow rate through the coolant loop and a ratio of the coolant flow through the different branches based on the cooling demand; when the estimated cooling demand increases up to a threshold, adjusting each of a coolant pump output and a position of a valve that divides coolant flow between the different branches to vary the ratio as a function of the AC head pressure and a portion of the flow requested via the condenser relative to the CAC; and when the estimated cooling demand increases beyond the threshold,Operating the coolant pump at maximum power and adjusting the position of the valve to maintain a predetermined ratio of coolant flow between the various branches. In any or all of the preceding examples, the valve is additionally or optionally a three-way valve that divides coolant flow between a first branch of the coolant circuit including the CAC and a second branch of the coolant circuit including the condenser, the second branch being arranged parallel to the first branch. In any or all of the preceding examples, estimating the cooling demand additionally or optionally includes estimating the cooling demand at the air conditioning condenser based on each of the vehicle operator's cabin cooling demands,Ambient temperature and ambient humidity, and estimating cooling demand at the CAC based on driver torque demand and manifold charge temperature. In any or all of the preceding examples, the AC condenser is additionally or optionally further coupled to a refrigerant circuit different from the coolant circuit, the refrigerant circuit including a thermal expansion valve, an AC compressor, and an AC clutch, and wherein the AC head pressure at the refrigerant circuit is estimated. In any or all of the preceding examples, varying the ratio as a function of the AC head pressure additionally or optionally includes increasing the ratio of refrigerant flow through the second branch including the AC condenser when the AC head pressure estimated at the refrigerant circuit exceeds a reference AC head pressure.where the reference AC head pressure is plotted as a function of coolant flow rate and coolant temperature at an outlet of a low-temperature automotive radiator fluidly coupled to the CAC.

[0118] Another example vehicle system includes: a vehicle cabin; an air conditioning (AC) system including a condenser for cooling cabin air; a boosted engine system including an engine and a turbocharger compressor coupled upstream of a charge air cooler (CAC); a refrigerant circuit circulating refrigerant through the condenser, the circuit including a pressure sensor; a coolant circuit circulating coolant through each of the condenser, the CAC, and a transmission oil cooler (TOC), the coolant circuit including an electric pump, a proportional valve, and a temperature sensor; and a controller including computer-readable instructions to: map a desired coolant flow rate through the condenser based on the coolant temperature when a cabin cooling demand changes between a lower limit and an upper limit;Adjusting a power of the pump based on the estimated refrigerant flow rate; and adjusting the position of the valve based on an actual AC head pressure estimated at the refrigerant circuit relative to a reference AC head pressure mapped based on the refrigerant temperature. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: when the cabin cooling demand falls below the lower threshold, adjusting the position of the valve to maintain a lower threshold refrigerant flow rate through the condenser;and when the cabin cooling demand exceeds the upper threshold, adjusting the position of the valve to maintain the lower threshold coolant flow rate through the CAC. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: in response to each of the cabin cooling and an engine cooling demand exceeding the upper threshold, increasing power of the pump while adjusting the position of the valve to maintain a fixed ratio of the coolant flow rate through the condenser relative to the CAC. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: mapping the desired coolant flow rate through the condenser as a first function of coolant temperature; and mapping the reference AC head pressure as a second, different function of coolant temperature.

[0119] An example method for operating a vehicle air conditioning system includes: estimating a desired coolant flow rate through a coolant circuit based on a cooling demand at each of an air conditioning condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of the coolant circuit; modeling a reference air conditioning (AC) head pressure in a refrigerant circuit coupled to the condenser based on each of the desired coolant flow rate and a coolant temperature; indicating degradation of the refrigerant circuit in response to the reference AC head pressure relative to an actual AC head pressure; and in response to the indication, adjusting a ratio of coolant flow through the condenser relative to the CAC.In any or all of the preceding examples, indicating additionally or optionally includes indicating increased condenser loading when the actual AC head pressure exceeds the reference AC head pressure. In any or all of the preceding examples, adjusting the ratio additionally or optionally includes, in response to the indication of increased condenser loading, increasing refrigerant flow through the condenser. In any or all of the preceding examples, the method additionally or optionally further comprises, when the actual AC head pressure is below the reference AC head pressure, integrating an error between the actual AC head pressure and the reference AC head pressure over a duration and indicating degradation of the refrigerant cycle based on the integrated error.In any or all of the preceding examples, indicating additionally or optionally includes indicating refrigerant circuit blockage when the integrated error is above a first threshold error, and indicating refrigerant circuit leakage when the integrated error is above a second threshold error and below the first threshold error. In any or all of the preceding examples, adjusting the ratio additionally or optionally includes, in response to the indication of refrigerant circuit blockage, decreasing the refrigerant flow through the condenser while increasing the refrigerant flow through the CAC, and, in response to the indication of refrigerant circuit leakage, increasing the refrigerant flow through the condenser while maintaining or decreasing the refrigerant flow through the CAC.In any or all of the preceding examples, the coolant circuit additionally or optionally includes a first branch including the condenser, a second branch including the CAC, wherein the second branch is arranged parallel to the first branch, and wherein increasing coolant flow through the condenser includes biasing a proportional valve coupled upstream of the first and second branches toward the first branch, and wherein decreasing coolant flow through the condenser includes biasing the proportional valve toward the second branch.In any or all of the preceding examples, the estimated desired coolant flow rate is additionally or optionally increased when one or more of an increase in air conditioning condenser cooling demand in response to a vehicle operator cabin cooling demand, an increase in CAC cooling demand in response to vehicle operator torque demand, and when TOC cooling demand increases in response to transmission torque converter slip occur. In any or all of the preceding examples, the method additionally or optionally further comprises distinguishing refrigerant circuit degradation due to clogging from degradation due to leakage based on an error magnitude and direction between the reference AC head pressure and the actual AC head pressure. In any or all of the preceding examples, the coolant circuit is additionally or optionally coupled to the refrigerant circuit at the condenser.

[0120] Another example method includes: during a first condition, inferring a refrigerant level below a threshold at an AC refrigerant loop based on an actual head pressure at an AC condenser being below an expected head pressure, wherein the expected head pressure is based on a flow rate and temperature of refrigerant flowing through a refrigerant loop different from the refrigerant loop and coupled to the AC condenser; and during a second condition, inferring a blockage in the AC refrigerant loop based on the actual head pressure at the AC condenser being below the expected head pressure.In any or all of the preceding examples, the expected head pressure is based on the flow rate of coolant flowing through the coolant loop, additionally or optionally based on the flow rate of coolant flowing in parallel through each of the condenser and a charge air cooler (CAC), and further based on a coolant temperature at an outlet of a low-temperature radiator fluidly coupled to the CAC. In any or all of the preceding examples, additionally or optionally, during the first condition, an integrated error between the actual head pressure and the expected head pressure is below a threshold for a duration, and during the second condition, the integrated error is above the threshold.In any or all of the preceding examples, the method additionally or optionally further comprises, during the first condition, in response to the refrigerant level being below the threshold, increasing a refrigerant flow rate through the condenser, and during the second condition, in response to the blockage, decreasing the refrigerant flow rate through the condenser. In any or all of the preceding examples, the method additionally or optionally further comprises, during the first condition, setting a diagnostic code to prompt a vehicle operator to add refrigerant, and during the second condition, setting a diagnostic code to prompt a vehicle operator to replace a refrigerant line.In any or all of the preceding examples, increasing coolant flow through the condenser additionally or optionally includes adjusting a proportional valve of the coolant circuit to bias coolant flow through the condenser, and wherein decreasing coolant circulation through the condenser includes adjusting the proportional valve to bias coolant flow through the CAC. In any or all of the preceding examples, the method additionally or optionally further comprises, during a third condition, deriving increased pumping work on the condenser based on an actual head pressure on the condenser being higher than the expected head pressure, and in response to the deriving, increasing coolant flow through the condenser.

[0121] Another example vehicle system includes: a vehicle cabin; an air conditioning (AC) system including an evaporator for cooling cabin air; a boosted engine system including an engine and a turbocharger compressor coupled upstream of a charge air cooler (CAC); a refrigerant circuit circulating refrigerant through the condenser, the circuit including a pressure sensor; a coolant circuit circulating coolant through each of the condenser, the CAC, and a transmission oil cooler (TOC), the coolant circuit including an electric pump, a proportional valve, and a temperature sensor;and a controller including computer-readable instructions to: map each of a desired refrigerant flow rate through the condenser and a reference AC head pressure to the refrigerant circuit based on a refrigerant temperature when a cooling demand of refrigerant circuit components changes; adjust a performance of the pump based on the estimated refrigerant flow rate; indicate degradation of the refrigerant circuit based on an error between an actual head pressure and the reference head pressure; and adjust a position of the valve based on the indication. In any or all of the preceding examples, the indicating additionally or optionally includes: when the actual head pressure is higher than the reference head pressure, indicating condenser loading and biasing the valve position toward the condenser;if the actual head pressure is less than the reference head pressure and an integrated error is smaller, indicating refrigerant line leakage and biasing the valve position toward the condenser; and if the actual head pressure is less than the reference head pressure and the integrated error is greater, indicating refrigerant line blockage and biasing the valve position toward the CAC. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: map the desired refrigerant flow rate through the condenser as a first function of refrigerant temperature; and map the reference AC head pressure as a second, different function of refrigerant temperature.

[0122] An example method includes adjusting a flow of coolant through each of an air conditioning condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of a coolant circuit to maintain an estimated transmission oil temperature (TOT) below a threshold, wherein the TOT is estimated based on a torque converter slip ratio. In any or all of the preceding examples, the adjusting additionally or optionally includes flowing coolant through the condenser, CAC, and TOT at a coolant flow rate mapped as a function of coolant temperature, AC head pressure, CAC cooling demand, and TOT. In any or all of the preceding examples, the adjusting additionally or optionally includes adjusting a power of an electric coolant pump to flow coolant at the coolant flow rate.In any or all of the preceding examples, the proportional valve is additionally or optionally coupled upstream of a first branch of the coolant circuit including the condenser and a second branch of the coolant circuit including the CAC, the second branch being arranged parallel to the first branch. In any or all of the preceding examples, the adjusting additionally or optionally further includes adjusting the position of a proportional valve configured to apportion coolant between the condenser and the CAC, the position of the proportional valve being biased toward the condenser in the first branch when a TOT cooling demand exceeds the coolant flow required in the first and second branches.In any or all of the preceding examples, the TOC is additionally or optionally coupled in a third branch of the coolant circuit, wherein the third branch is parallel to and bypasses each of the first and second branches, wherein the third branch includes a one-way valve. In any or all of the preceding examples, the coolant circuit is additionally or optionally coupled at the TOC to a transmission oil circuit, wherein the transmission oil circuit includes a transmission and a torque converter, and wherein the coolant circuit is coupled at the condenser to a refrigerant circuit of an air conditioning system.In any or all of the preceding examples, the position of the proportional valve is additionally or optionally further adjusted based on an estimated AC head pressure estimated at the refrigerant circuit relative to a reference head pressure mapped based on a function of coolant temperature, wherein the proportional valve is biased toward the condenser when the estimated AC head pressure exceeds the reference head pressure. In any or all of the preceding examples, the method additionally or optionally further comprises, in response to the estimated transmission oil temperature (TOT) exceeding the threshold, opening the one-way valve, and in response to the estimated transmission oil temperature (TOT) falling below the threshold, closing the one-way valve.In any or all of the preceding examples, the estimated transmission oil temperature is additionally or optionally increased as the torque converter slip ratio increases.

[0123] Another example method for a vehicle system includes: estimating a first transmission oil temperature of a transmission oil circuit via a temperature sensor; estimating a second transmission oil temperature of the transmission oil circuit as a function of a torque converter slip ratio; and adjusting a coolant flow through a coolant circuit including a transmission oil cooler (TOC), an air conditioning (AC) condenser, and a charge air cooler (CAC) based on a higher of the first and second transmission oil temperatures. In any or all of the preceding examples, the first transmission oil temperature additionally or optionally indicates an oil temperature at an oil pan of the transmission oil circuit, and wherein the second transmission oil temperature indicates an oil temperature at an output of a torque converter of the transmission oil circuit.In any or all of the preceding examples, adjusting coolant flow additionally or optionally includes adjusting a power of an electric coolant pump of the coolant circuit to flow coolant at a desired coolant flow rate, where the desired coolant flow rate is mapped as a function of coolant temperature, AC head pressure, CAC cooling demand, and TOT. .

[0124] In any or all of the preceding examples, the transmission oil circuit is additionally or optionally coupled to the coolant circuit at the TOC, wherein the coolant circuit is further coupled to a refrigerant circuit of an air conditioning system at the condenser, wherein the AC head pressure is estimated at the refrigerant circuit. In any or all of the preceding examples, adjusting the coolant flow additionally or optionally further includes adjusting the position of a proportional valve configured to apportion coolant between the condenser and the CAC, wherein the position of the proportional valve is biased toward one of the condenser and the CAC having a lower cooling demand, wherein the cooling demand at the condenser is based on a cabin cooling demand, and wherein the cooling demand at the CAC is based on a driver torque demand.In any or all of the preceding examples, the second transmission oil temperature is additionally or optionally further estimated as a function of the engine speed and the first transmission oil temperature, wherein the estimated second transmission oil temperature is increased as one or more of the engine speed, the torque converter slip ratio, and the estimated first transmission oil temperature increases.

[0125] Another example vehicle system includes: a vehicle cabin; an air conditioning (AC) system including a condenser, evaporator, and compressor for cooling cabin air; a boosted engine system including an engine and a turbocharger compressor coupled upstream of a charge air cooler (CAC); a refrigerant circuit circulating refrigerant through the condenser, the circuit including a pressure sensor; an oil circuit circulating oil drawn from an oil pan through each of the transmission, a torque converter, and a transmission oil cooler (TOC), the oil circuit including an oil temperature sensor and a transmission valve; a coolant circuit circulating coolant through each of the condenser, CAC, and TOC, the coolant circuit including an electric pump, a proportional valve, and a coolant temperature sensor;and a controller including computer-readable instructions to: when the torque converter slip ratio is above a threshold, open the transmission valve to circulate coolant through the TOC and adjust a power of the pump to provide a coolant flow rate through the TOC mapped as a function of a modeled transmission oil temperature;and if the torque converter slip ratio is below the threshold, opening the transmission valve to circulate coolant through the TOC and adjusting the power of the pump and the position of the proportional valve to provide a coolant flow rate through the TOC mapped as a function of an estimated transmission oil temperature. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: estimating the estimated transmission oil temperature via the oil temperature sensor;and modeling the modeled transmission oil temperature as a function of each of the engine speed, the torque converter slip ratio, and the estimated transmission oil temperature. In any or all of the preceding examples, adjusting additionally or optionally includes: when the estimated transmission oil temperature or the modeled transmission oil temperature exceeds a threshold temperature, increasing a power of the pump; biasing the proportional valve toward the condenser when a CAC cooling demand exceeds a cabin cooling demand;and biasing the proportional valve toward the CAC when the cabin cooling demand exceeds the CAC cooling demand. In any or all of the preceding examples, the controller additionally or optionally includes further instructions to: close the transmission valve to interrupt coolant flow through the TOC in response to the estimated transmission oil temperature or the modeled transmission oil temperature falling below the threshold temperature;

[0126] It should be noted that the example control and estimation routines included in this document 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-volatile memory and executed by the control system, including the controller in combination with the various sensors, actuators, and other engine hardware. The specific 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. Accordingly, 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 necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but rather 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 may graphically represent code programmed onto non-transitory memory of the computer-readable storage medium in the engine control system, wherein the described acts are performed by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.

[0127] It is understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments are not to be considered limiting, as numerous variations are possible. For example, the above technology can be applied to V6, I4, I6, V12, horizontally opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and configurations, and other features, functions, and / or characteristics disclosed herein. Reference symbol: 10 Engine 12 Control 13 turbochargers 18 intercoolers 19 Wave 20 throttle valve 22 Engine intake manifold 30 combustion chambers 35 exhaust duct 36 exhaust manifold 50 EGR channel 51 EGR cooler 52 EGR valve 55 Temperature sensor / compressor inlet temperature sensor 56 Pressure sensor / compressor inlet pressure sensor 57 Humidity sensor / compressor inlet humidity sensor 66 injection 81 actuators 82 Air conditioning (AC) system 84 vehicle HVAC systems 90 Wastegate 92 Wastegate actuator 100 engine system 112 air purifiers 114 compressors 116 turbines 124 Manifold air pressure (MAP) sensor 126 exhaust gas sensor 128 Exhaust gas temperature sensor 129 Exhaust pressure sensor 170 Emissions control 200 cooling system 202 Coolant circuit / first coolant loop 204 second coolant loop 206 Low-temperature (LT) car radiators 207 fans 208 coolant pump 210 water-air intercooler (CAC) 216 high-temperature car radiators 217 car radiator fan 218 engine block 220 Transmission oil cooler (TOC) 242 first subloop 244 second subloop 246 Main Loop 250 proportional valve 260 AC system condenser 270 Air conditioning system / AC system / refrigerant circuit 272 thermal expansion valve / refrigerant circuit 274 AC coupling 276 AC compressors 280 Transmission oil circuit 282 oil pan 284 gearboxes 286 Temperature sensor 290 turbocharger cooler

Claims

[1] Method comprising: Estimating a transmission oil temperature (TOT) at a torque converter (TC) outlet based on a torque converter slip ratio; and Adjusting a flow of coolant through each of an air conditioning (AC) condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of a coolant circuit to maintain the estimated transmission oil temperature (TOT) below a threshold in response to estimating the TOT based on a torque converter slip ratio. [2] The method of claim 1, wherein adjusting includes flowing coolant through the condenser, the CAC, and the TOC at a coolant flow rate mapped as a function of coolant temperature, AC head pressure, CAC cooling demand, and TOT. [3] The method of claim 2, wherein adjusting the flow of coolant includes adjusting a power of an electric coolant pump to flow coolant at the coolant flow rate. [4] The method of claim 3, wherein a proportional valve is coupled upstream of a first branch of the coolant circuit including the condenser and a second branch of the coolant circuit including the CAC, the second branch being arranged in parallel with the first branch. [5] The method of claim 4, wherein adjusting the flow of coolant further includes adjusting a position of the proportional valve configured to apportion coolant between the condenser and the CAC, the position of the proportional valve biased toward the condenser in the first branch when a TOT cooling demand exceeds the coolant flow required in the first and second branches. [6] The method of claim 4, wherein the TOC is coupled in a third branch of the coolant circuit, the third branch being parallel to and bypassing each of the first and second branches, the third branch including a one-way valve. [7] The method of claim 4, wherein the coolant circuit at the TOC is coupled to a transmission oil circuit, the transmission oil circuit including a transmission and a torque converter, and wherein the coolant circuit at the condenser is coupled to a refrigerant circuit of an air conditioning system. [8] The method of claim 7, wherein a position of the proportional valve is further adjusted based on an estimated AC head pressure estimated at the refrigerant circuit relative to a reference head pressure mapped based on a function of coolant temperature, the proportional valve being biased toward the condenser when the estimated AC head pressure exceeds the reference head pressure. [9] The method of claim 6, further comprising, in response to the estimated transmission oil temperature (TOT) exceeding the threshold, opening a one-way valve, and, in response to the estimated transmission oil temperature (TOT) falling below the threshold, closing a one-way valve. [10] The method of claim 1, wherein the estimated TOT is increased as the torque converter slip ratio increases, wherein the TOT is estimated during torque converter slip / heat generation conditions, and wherein the slip ratio used to estimate the TOT is based on an output speed relative to an input speed of the torque converter during the torque converter slip / heat generation conditions. [11] Vehicle system comprising: a vehicle cabin; an air conditioning (AC) system that includes a condenser, evaporator, and compressor for cooling cabin air; a turbocharged engine system including an engine and a turbocharger compressor coupled upstream of an intercooler (CAC); a refrigerant circuit that circulates refrigerant through the condenser, the circuit including a pressure sensor; an oil circuit that circulates oil drawn from an oil pan through each of the transmission, a torque converter, and a transmission oil cooler (TOC), the oil circuit including an oil temperature sensor and a transmission valve; a coolant circuit that circulates coolant through both the condenser and the CAC and also the TOC, the coolant circuit including an electric pump, a proportional valve, and a coolant temperature sensor; and a controller that includes computer-readable instructions for: when the torque converter slip ratio is above a threshold, opening the transmission valve to circulate coolant through the TOC and adjusting a power of the pump to provide a coolant flow rate through the TOC mapped as a function of a modeled transmission oil temperature; and when the torque converter slip ratio is below the threshold, opening the transmission valve to circulate coolant through the TOC, and adjusting the power of the pump and the position of the proportional valve to provide a coolant flow rate through the TOC mapped as a function of an estimated transmission oil temperature. [12] The system of claim 11, wherein the controller includes further instructions to: Estimating the estimated transmission oil temperature via the oil temperature sensor; and Modeling the modeled transmission oil temperature as a function of each of the engine speed, the torque converter slip ratio, and the estimated transmission oil temperature. [13] The system of claim 12, wherein setting includes: if the estimated transmission oil temperature or the modeled transmission oil temperature exceeds a threshold temperature, Increasing the pump’s performance; Biasing the proportional valve towards the condenser when a CAC cooling demand exceeds a cabin cooling demand, and Bias the proportional valve towards the CAC when the cabin cooling demand exceeds the CAC cooling demand. [14] The system of claim 13, wherein the controller includes further instructions to: Close the transmission valve to interrupt coolant flow through the TOC in response to the estimated transmission oil temperature or the modeled transmission oil temperature falling below the threshold temperature.

Images