METHOD AND SYSTEM FOR WATER INJECTION CONTROL

Abstract

Methods for an internal combustion engine, comprising: Injecting a larger proportion of water upstream than downstream of an intercooler while the cooler is operating in a heating mode; and Injecting a larger proportion of water downstream than upstream of the charge air cooler while the cooler is operating in a cooling mode.

Description

Field of invention

[0001] The present invention relates generally to methods and systems for injecting water into an internal combustion engine which has a charge air cooler. General state of the art / Summary

[0002] Internal combustion engines may incorporate water injection systems that inject water from a reservoir into a variety of locations, including an intake manifold upstream of the internal combustion engine cylinders, an intake port upstream of the cylinder intake valves, or directly into the internal combustion engine cylinders.

[0003] DE 10 2016 207 189 A1 discloses an internal combustion engine with an engine structure and several cylinders. One of the cylinders is a special exhaust gas recirculation (EGR) cylinder, wherein the exhaust tract connected to the EGR cylinder also has a connection to the intake manifold, which in turn is connected to the intake tract. The EGR cooler is connected to the EGR system. The charge air cooler is connected to the intake / exhaust gas recirculation mixer. A condensate separator for collecting condensate from the EGR cooler and / or the charge air cooler is provided. An injection system injects condensate from the condensate separator into the cylinders.

[0004] An example of an internal combustion engine system with multiple injector locations is presented by Brehob et al. in US 7,426,918 B2. Injecting water into the internal combustion engine's intake air can increase fuel economy and engine power, as well as reduce internal combustion engine emissions. When water is injected into the internal combustion engine's intake or cylinders, heat is transferred from the intake air and / or internal combustion engine components to the water. This heat transfer causes evaporation, which results in cooling. Injecting water into the intake air (e.g., in the intake manifold) reduces both the intake air temperature and the combustion temperature at the internal combustion engine cylinders. By cooling the intake air charge, knocking can be reduced without enriching the air-fuel mixture. This can also allow for a higher compression ratio, advanced ignition timing, and reduced exhaust gas temperature.Consequently, fuel efficiency increases. Furthermore, a higher volumetric efficiency can result in increased torque.

[0005] However, the benefits of water injection can be limited by the relative humidity of the air charge. For example, the charge cooling effect of water injection relies on the evaporative cooling of the injected water. However, in warm, humid air, a smaller fraction of the injected water may evaporate, resulting in reduced charge cooling. Conversely, the charge dilution effect of water injection relies on the presence of water dispersed in warm air, which disperses further under warm, humid conditions.

[0006] The inventors in this document further recognized that the coolant flow through an intercooler (CAC) serves to maintain the temperature of the air charge exiting the cooler. During conditions when supercharging is provided by the upstream compressor, the air charge entering the cooler is hot, and the coolant flow cools the air charge before it enters the internal combustion engine. In other words, the CAC operates in a cooling mode, with heat flowing from the air charge to the coolant. However, during conditions when the air charge entering the cooler is cold, the coolant flow through the intercooler can be used to heat the air charge. In other words, the intercooler will operate in a heating mode, with heat flowing from the coolant to the air charge.Consequently, the benefits of water injection can be enhanced by injecting water upstream of an intercooler during dry and cold ambient conditions, while water is injected downstream of the intercooler under humid or hot conditions. By effectively utilizing the different directions of heat flow at the CAC during cold and dry conditions, water injection upstream of the CAC can be used to preheat the air supplied to the combustion engine and reduce moisture. Conversely, during hot conditions, water injection downstream of the CAC can be used to provide charge cooling.An example procedure for an internal combustion engine involves: injecting a larger proportion of water upstream of an intercooler while the cooler is operating in a heating mode; and injecting a larger proportion of water downstream of the intercooler while the cooler is operating in a cooling mode.

[0007] For example, in response to a dilution request from the internal combustion engine while operating on natural intake, a specific amount of water injection required to address the dilution request can be determined. If the ambient conditions at the time of the dilution request are dry and cold (for example, when a vehicle is traveling through desert regions), a larger proportion of the determined water injection quantity can be injected into the engine upstream of a CAC (Cooling Acquisition Control Unit), and a remaining, smaller proportion can be injected downstream of the CAC.In comparison, in response to a cooling request from the internal combustion engine (for example, for knock relief) received while the engine is operating with turbocharging, a specific amount of water injection required for cooling the engine can be determined. If the ambient conditions are warm or hot at the time of the engine cooling request, a larger proportion of the determined water injection quantity can be injected into the engine downstream of a condensate accumulator (CAC), and a remaining, smaller proportion can be injected directly into an engine cylinder or upstream of the CAC. In either case, the injected water quantity can be adjusted, taking into account the condensate level at the CAC, to reduce the likelihood of misfires induced by condensate.

[0008] In this way, the advantages of water injection can be extended by utilizing the airflow through a CAC during cold, dry conditions, in conjunction with water injection at a point upstream of the CAC to warm and humidify the air charge before it is fed into an internal combustion engine. Injecting the water upstream adds the heat of vaporization to the water, increasing the total amount of water that can be injected into the internal combustion engine (relative to a point downstream of the CAC), thus enhancing the charge dilution effect of the water injection. By extracting heat from the coolant circulating through the CAC during cold ambient conditions, the air charge can be warmed after passing through the CAC without the need for a dedicated heating element.By utilizing the airflow through the CAC during hot, supercharged conditions, in conjunction with water injection at a point downstream of the CAC to cool the charge before it enters the internal combustion engine, the charge-cooling capability of the water injection system is enhanced. Providing knock relief via charge-cooling water injection reduces the reliance on retarded ignition timing, thereby improving fuel economy.

[0009] It is understood that the foregoing summary is intended to present a selection of concepts in simplified form, which are described in more detail in the detailed description. It is not intended to identify key or essential functions of the claimed subject matter, the scope of which is defined exclusively by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that are intended to overcome any disadvantages that may be listed above or in any part of this disclosure. Brief description of the drawings Fig. Figure 1 shows a schematic drawing of an internal combustion engine system configured for water injection. Fig. Figure 2 shows an example of the change in relative humidity as a function of ambient temperature and pressure. Fig. Figure 3 shows a high-level flow diagram for changing the point of water injection depending on changes in ambient temperature and humidity. Fig. Figure 4 shows a diagram illustrating exemplary adjustments to the amount of water injected and the timing control to compensate for an unfavorable water distribution between the cylinders. Detailed description

[0010] The following description refers to systems and methods for extending the benefits of water injection from a water injection system coupled to a vehicle internal combustion engine, as in relation to the vehicle system of Fig. 1 described. The internal combustion engine system can be configured to inject water at various points, including upstream and downstream of a combustion air cooler (CAC), to provide various benefits of water injection, such as charge air cooling, cooling of internal combustion engine components, and internal combustion engine dilution. A controller can be configured to execute a control routine, such as the example routine from Fig. 3, to select between a quantity of water to be injected at a point upstream of the CAC relative to a point downstream of the CAC, based on internal combustion engine cooling and dilution requirements, and further based on ambient temperature and humidity conditions. Due to the change in relative humidity depending on temperature and pressure (as in Fig. (As shown in Figure 2), the advantages of charge cooling in a water injection system can be enhanced by injecting the water at a point downstream of the CAC (Cold Acceleration Control). Conversely, the advantages of charge dilution in a water injection system can be enhanced by injecting the water at a point upstream of the CAC. An example of a water injection system is shown in Figure 2. Fig. Figure 4 illustrates this. By allowing more water to be injected into the internal combustion engine, the benefits of water injection can be extended over a wider range of internal combustion engine operating conditions. Consequently, the use of water can be improved to enable significant performance improvements in a vehicle with regard to fuel economy.

[0011] Fig. Figure 1 shows an embodiment of an internal combustion engine system 100 configured with a water injection system 60. The internal combustion engine system 100 is coupled to the motor vehicle 102, which is shown schematically. The internal combustion engine system 100 includes an internal combustion engine 10, illustrated in this document as a turbocharged internal combustion engine coupled with a turbocharger 13, including a compressor 14 driven by a turbine 116. Specifically, fresh air is introduced into the internal combustion engine 10 along the intake duct 142 via an air filter 31 and flows to the compressor 14. The compressor can be a suitable intake air compressor, such as a forced-air compressor driven by an electric motor or drive shaft.In the internal combustion engine system 100, the compressor is represented as a turbocharger-compressor mechanically coupled to the turbine 116 via a shaft 19, the turbine 116 being driven by the expansion of the exhaust gases from the internal combustion engine. In one embodiment, the compressor and the turbine can be coupled within a twin-scroll turbocharger. In another embodiment, the turbocharger can be a variable geometry turbocharger (VGT), wherein the turbine geometry is actively changed depending on the rotational speed of the internal combustion engine and other operating conditions.

[0012] As in Fig. As shown in Figure 1, the compressor 14 is coupled to the throttle valve (e.g., intake throttle valve) 20 via the charge air cooler (CAC) 118. The CAC can be an air-to-air or air-to-coolant (as in the present example) heat exchanger. The throttle valve 20 is coupled to the internal combustion engine intake manifold 122. From the compressor 14, the hot, compressed air charge enters the inlet of the CAC 118, cools down as it flows through the CAC, and then exits to flow through the throttle valve 20 to the intake manifold 122. In the figure shown in Fig. In the embodiment shown in Figure 1, the pressure of the air charge within the intake manifold is detected by the absolute manifold pressure (MAP) sensor 124, and the boost pressure is detected by the boost pressure sensor 24. A compressor bypass valve (not shown) can be connected in series between the inlet and outlet of the compressor 14. The compressor bypass valve can be a normally closed valve configured to open under selected operating conditions to release excess boost pressure. For example, the compressor bypass valve can open in response to compressor pumping.

[0013] Furthermore, CAC 118 is thermally coupled to the coolant system 120. The coolant system 120 may include a radiator 130 for dissipating heat from the heated coolant to the atmosphere. The coolant system 120 may also include additional coolant lines or loops (not shown) that couple the coolant system to the internal combustion engine system, allowing coolant to circulate around the internal combustion engine block 182 (to accelerate the heating of the internal combustion engine) and / or through the EGR cooler 50. Heat transfer between CAC 118 and the coolant system 120 serves to maintain a temperature of the air charge exiting CAC 118 (e.g., at or approximately 35°C). During supercharged internal combustion engine operation, the intake air compressed at the compressor 14 is supplied to the internal combustion engine after passing through CAC 118. After passing through the compressor, the air is heated.Therefore, during turbocharged combustion engine operation, the CAC operates in a cooling mode, in which heat is drawn from the air into the coolant flowing through the CAC, thus cooling the air to a set temperature. Heated coolant (which may be water or other possible coolants) enters the radiator 130 via the coolant loop 131, where the heat is dissipated into the atmosphere (or transferred to the combustion engine block to accelerate the warm-up of the combustion engine). The cooled coolant then exits the radiator 130 and flows back to the CAC 118 via the coolant loop 131. (The arrows indicate the direction of coolant flow.) In contrast, during self-intake conditions, when the intake air is at ambient temperature, the CAC operates in a heating mode, in which heat is drawn from the coolant into the air, warming the air to the set temperature.

[0014] The intake manifold 122 is coupled to a series of combustion chambers or cylinders 180 by a series of intake valves (not shown) and intake distributors (e.g., intake ports) 185. As shown in Fig. As shown in Figure 1, the intake manifold 122 is located upstream of all combustion chambers 180 of the internal combustion engine 10. Additional sensors, such as the intake manifold temperature sensor (MCT) 33 and the intake air temperature sensor (ACT) 25, may be included to determine the intake air temperature at the respective points in the intake duct. The air temperature, in conjunction with the internal combustion engine coolant temperature, can also be used to calculate, for example, the amount of fuel supplied to the internal combustion engine.

[0015] Each combustion chamber can further include a knock sensor 183 for identifying and differentiating abnormal combustion events, such as knocking and pre-ignition. In alternative embodiments, one or more knock sensors 183 can be coupled to selected locations of the internal combustion engine block. Furthermore, as further described below with regard to Fig. As explained in section 5, an output of the knock sensors can be used to detect unfavorable distribution of water to the individual cylinders of the internal combustion engine, whereby the water is injected upstream of all combustion chambers 180.

[0016] The combustion chambers are further coupled to the exhaust manifold 136 via a series of exhaust valves (not shown). The combustion chambers 180 are closed off by the cylinder head 182 and coupled to the fuel injectors 179 (while only one fuel injector is located in the cylinder head). Fig. As shown in Figure 1, each combustion chamber includes a fuel injector coupled to it. Fuel can be supplied to the fuel injector 179 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel distribution line. The fuel injector 179 can be configured as a direct injector for injecting fuel directly into the combustion chamber 180, or as a port injector for injecting fuel into an intake port upstream of an intake valve of the combustion chamber 180.

[0017] In the illustrated embodiment, a single exhaust manifold 136 is shown. However, in other embodiments, the exhaust manifolds can include a plurality of exhaust manifold sections. Configurations with a plurality of exhaust manifold sections can allow effluent from different combustion chambers to be routed to different locations in the internal combustion engine system. The universal exhaust gas lambda (UEGO) sensor 126 is shown coupled to the exhaust manifold 136 upstream of the turbine 116. Alternatively, the UEGO sensor 126 can be replaced by a dual-state exhaust gas lambda sensor.

[0018] As in Fig. As shown in Figure 1, the 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, a portion of the exhaust gas can instead be routed through a boost pressure control valve (not shown), bypassing the turbine. The combined flow from the turbine and the boost pressure control valve then flows through the emission control device 170. In general, one or more emission control devices 170 can include one or more exhaust aftertreatment catalysts configured to catalytically treat the exhaust gas flow, thereby reducing the amount of one or more substances in the exhaust gas stream.

[0019] The treated exhaust gases from the emission control device 170 can be released into the atmosphere, either wholly or partially, via the exhaust pipe 35. Depending on the operating conditions, however, a portion of the exhaust gas can instead be diverted to an exhaust gas recirculation (EGR) channel 151, through the EGR cooler 50 and the EGR valve 152, to the compressor inlet 14. In this way, the compressor is configured to draw in exhaust gas taken from downstream of the turbine 116. The EGR valve 152 can be opened to allow a controlled amount of cooled exhaust gas to the compressor inlet for desired combustion and emission control characteristics. Thus, the internal combustion engine system 100 is adapted to provide external low-pressure (LP) EGR.The rotation of the compressor, in addition to the relatively long low-pressure EGR flow path in the combustion engine system 100, provides excellent homogenization of the exhaust gas into the intake air charge. Furthermore, the arrangement of the EGR extraction and mixing points provides effective cooling of the exhaust gas for a larger available EGR mass and higher power output. In other embodiments, the EGR system can be a high-pressure EGR system, with the EGR channel 151 connecting upstream of the turbine 116 to downstream of the compressor 14. In some embodiments, the MCT sensor 33 can be positioned to determine the intake manifold charge temperature, the charge of which may contain air and exhaust gas recirculated through the EGR channel 151.

[0020] The intake manifold 122 can further include an intake gas lambda sensor 34. In one example, the lambda sensor is a UEGO sensor. The intake gas lambda sensor can be configured to provide an estimate of the oxygen content of the fresh air received in the intake manifold. For this purpose, during EGR operation, a change in the oxygen concentration at the sensor can be used to derive an EGR quantity and for precise EGR flow control. In the illustrated example, the lambda sensor 34 is positioned downstream of the throttle valve 20 and downstream of the charge air cooler 118. However, in alternative embodiments, the lambda sensor can be located upstream of the throttle valve.The intake lambda sensor 34 can be used to estimate the intake oxygen concentration and to derive an EGR flow rate through the combustion engine based on a change in the intake oxygen concentration when the EGR valve 152 opens. Likewise, the intake lambda sensor 34 can be used to estimate the intake oxygen concentration and derive a dilution for the combustion engine or a change in intake humidity based on a change in the intake oxygen concentration after water injection into the intake manifold.

[0021] The combustion chamber 180 also receives water and / or water vapor via the water injection system 60. Water from the water injection system 60 can be injected into the combustion engine intake or directly into the combustion chambers 180 through one or more of the water injection nozzles 44-48. For example, water can be injected into the intake manifold 122, upstream of the CAC 118 through water injection nozzle 44, or downstream of the CAC 118 and upstream of the throttle valve 20 through water injection nozzle 45, also referred to in this document as central water injection.

[0022] As in relation to Fig. As described in section 3, water injection upstream of the CAC can be advantageously used during conditions when the CAC is operating in heating mode to enhance the charge dilution effect of port water injection. For example, during conditions when the intake air is dry (relative humidity below a threshold) and the internal combustion engine is running naturally aspirated, water injection upstream of the CAC can be used to provide warm, humid air at the CAC outlet. CAC heat can be used to increase the water temperature (e.g., to 35°C) and the humidity of the air charge (e.g., to 100% relative humidity). Conversely, water injection downstream of the CAC can be advantageously used during conditions when the CAC is operating in cooling mode to enhance the charge cooling effect of port water injection.For example, during conditions where the intake air is warm and humid (relative humidity is higher than the threshold) and the internal combustion engine is turbocharged, water injection downstream of the CAC can be used to cool the air to the dew point of a lower temperature (e.g., ~15°C), even if the air exiting the CAC is warmer (e.g., at 35°C), in order to provide warm, humid air at the CAC outlet.

[0023] As another example, water can be injected into the intake manifold 122, downstream of the throttle valve, at one or more points, by the water injection nozzle 46. As yet another example, water can be injected into one or more intake manifolds (e.g., intake ports) 185 by the water injection nozzle 48 (also referred to in this document as port water injection), and / or directly into the combustion chamber 180 by the water injection nozzle 47 (also referred to in this document as direct water injection). In one embodiment, the injection nozzle 48 arranged in the intake manifolds can be angled towards and directed at the intake valve of the cylinder to which the intake manifold is attached. Consequently, the injection nozzle 48 can inject water directly into the intake valve, resulting in faster evaporation of the injected water and the advantage of greater dilution of the water vapor.In a further embodiment, the injection nozzle 48 can be angled away from the inlet valve and arranged so that it injects water against the flow direction of the intake air through the intake manifold. Consequently, more of the injected water can be carried into the airflow, thereby increasing the charge cooling advantage of the water injection.

[0024] Although only one representative injector 47 and injector 48 in Fig. As shown in Figure 1, each combustion chamber 180 and intake manifold 185 can contain its own injection nozzle. In alternative embodiments, the water injection system can include 60 water injection nozzles positioned at one or more of these locations. For example, in one embodiment, the internal combustion engine can contain only water injection nozzle 46. In another embodiment, the internal combustion engine can contain each of water injection nozzles 46, water injection nozzles 48 (one at each intake manifold), and water injection nozzles 47 (one at each combustion chamber).

[0025] The water injection system 60 can include: a water reservoir 63, a water lifting pump 62, a collection system 72, and a water filling channel 69. The water stored in the water reservoir 63 is supplied to the water injection nozzles 45-48 via the water channel 61 and the pipes or lines 161. In embodiments that include multiple injection nozzles, the water channel 61 can include a valve 162 (e.g., a pressure relief valve).

[0026] The system may include directional control valves, multi-way valves, proportioning valves, etc., to supply water to the various water injection nozzles through the corresponding pipelines. Alternatively, each pipeline (or water line) 161 may include corresponding valves within the water injection nozzles 45-48 to adjust the water flow through them. In addition to the water lifting pump 62, one or more additional pumps may be provided in the pipelines 161 to pressurize the water supplied to the injection nozzles, such as in the pipeline coupled to carry the water injection nozzle 47.

[0027] The water reservoir 63 can include a water level sensor 65 and a water temperature sensor 67, which can transmit information about the water conditions to the control unit 12. For example, under freezing conditions, the water temperature sensor 67 detects whether the water in the reservoir 63 is frozen or available for injection. In some embodiments, an internal combustion engine coolant channel (not shown) can be thermally coupled to the reservoir 63 to thaw frozen water. The level of water stored in the water reservoir 63, as determined by the water level sensor 65, can be transmitted to the driver and / or used to adjust the internal combustion engine operation. For example, a water level indicator or a display on the vehicle's instrument panel (not shown) can be used to transmit the water level.If the water level in water tank 63 is higher than a threshold level, it can be deduced that sufficient water is available for injection, and the water injection can be activated by the controller accordingly. Conversely, if the water level in water tank 63 is lower than the threshold level, it can be concluded that insufficient water is available for injection, and therefore the water injection can be deactivated by the controller.

[0028] In the illustrated embodiment, the water reservoir 63 can be manually filled via the water filling channel 69 and / or automatically filled by the collection system 72 via the water reservoir filling channel 76. The collection system 72 can be coupled to one or more vehicle components 74, so that the water reservoir can be filled internally with condensate collected from various internal combustion engine or vehicle systems. In one example, the collection system 72 can be coupled to an EGR system and / or exhaust system to collect water that condenses from the exhaust gas flowing through the system. In another example, the collection system 72 can be coupled to an air conditioning system (not shown) for collected water that condenses from the air flowing through an evaporator.In yet another example, the collection system 72 can be coupled to an external vehicle surface to collect rain or atmospheric condensation. The manual filling channel 69 can be fluidically coupled to a filter 68, which can remove some impurities contained in the water. A drain 92, including a drain valve 91, can be used to discharge water from the water reservoir 63 to a location outside the vehicle (e.g., onto the road), such as when the water quality is considered below a threshold and unsuitable for injection into the internal combustion engine (e.g., due to high conductivity or a high content of particulate matter). In one example, the water quality can be assessed based on the output of a sensor coupled to the water injection system 60 in water line 61.For example, water quality can be assessed based on the output of a conductivity sensor, a capacitance sensor, an optical sensor, a turbidity sensor, a density sensor, or any other type of water quality sensor.

[0029] Fig. 1 further comprises a control system 28. The control system 28 can be communicatively connected to various components of the internal combustion engine system 100 in order to execute the control routines and actions described in this document. The control system 28 can include an electronic digital controller 12. The controller 12 can be a microcomputer, including a microprocessor unit, input / output ports, an electronic storage medium for executable programs and calibration values, random-access memory, permanent memory, and a conventional data bus. The controller 12 can receive input from a variety of sensors 30, such as the various sensors of Fig. 1 receives input including transmission position, accelerator pedal position, brake request, vehicle speed, internal combustion engine speed, mass airflow through the internal combustion engine, boost pressure, ambient conditions (temperature, pressure, humidity), etc. Other sensors include CAC 118 sensors, such as CAC intake air temperature sensor, ACT sensor 125, exhaust pressure and temperature sensors 80, 82, and pressure sensor 124, CAC exhaust air temperature sensor and MCT sensor 33, intake oxygen sensor (IAO2) 34, knock sensor 183 for determining exhaust gas ignition and / or water distribution among the cylinders, and others. The control unit 12 receives signals from the various sensors of Fig. 1 and uses the various actuators from Fig. 1. To adapt the operation of the internal combustion engine based on the received signals and instructions stored in a memory of the control unit. For example, injecting water into the internal combustion engine may involve adjusting the pulse width of the injectors 44-48 to vary the amount of water injected, while simultaneously adjusting the timing of the water injection and the number of injection pulses. In some examples, the memory medium may be programmed with computer-readable data representing instructions that can be executed by the processor to perform the following (e.g., in Fig. 3) to carry out the described procedures, as well as other variants that are anticipated but not specifically listed.

[0030] In this way, the system of Fig. 1. A vehicle system comprising: an internal combustion engine; a compressor to provide a supercharged air charge to the internal combustion engine; an intercooler coupled downstream of the compressor; a coolant system for coolant circulating through the intercooler and the internal combustion engine; a first water injector coupled upstream of the intercooler and downstream of the compressor; a second water injector coupled downstream of the intercooler; an EGR duct including an EGR valve for exhaust gas recirculation from an exhaust manifold to an intake manifold, upstream of the compressor; a humidity sensor coupled to the intake manifold upstream of the compressor to estimate ambient humidity; a temperature sensor coupled to the intake manifold upstream of the compressor to estimate ambient temperature;and a control system with computer-readable instructions to: in response to the ambient temperature being below a temperature threshold, inject more water into the internal combustion engine upstream of the charge air cooler than downstream of the charge air cooler, while the compressor remains deactivated; and in response to the ambient temperature being above the temperature threshold, inject more water into the internal combustion engine downstream of the charge air cooler than upstream of the charge air cooler, while the compressor is activated.

[0031] The inventors of this document have recognized that changes in humidity as a function of temperature and pressure can be used synergistically to enhance the charge dilution effects of water injection during dry and / or cold conditions, and to enhance the charge cooling effects of water injection under warm and / or humid conditions. For example, a CAC temperature (or the temperature of the air charge at the CAC outlet) can be maintained at a substantially constant temperature, while the outlet temperature and humidity are varied by injecting water upstream of the CAC (to maximize the dilution effect) or downstream of the CAC (to maximize the cooling effect).

[0032] An example of a relationship between relative humidity and temperature, as well as intake manifold pressure, is shown in map 200 of Fig. 2 is shown. In an example, the characteristic curve of Fig. 2. These values ​​are generated during the calibration of the internal combustion engine and stored in the memory of the internal combustion engine control unit. The control unit can then reference the map during internal combustion engine operation to determine where water should be injected in an internal combustion engine in response to changes in ambient temperature and humidity.

[0033] Map 200 shows that at a given pressure (e.g., a given MAP), the amount of water vapor that can be carried in the air (indicated by the relative humidity) increases with increasing air temperature. Furthermore, the total amount of water vapor that can be carried in the air at a given temperature also increases with increasing pressure. Therefore, during dry and cold conditions, it is desirable to condition the intake air so that it meets the operating conditions of the combustion engine by heating the air in addition to injecting water. This is particularly advantageous under part-load conditions, as the dilution effect of water injection is beneficial for reducing pumping losses similar to those of EGR. While water injection after CAC increases the relative humidity of the intake air, this occurs at the cost of a temperature reduction, which counteracts the effect of CAC used in heating mode.In this case, injection before the CAC is more advantageous because the dry, cold air carries just the right amount of water, which can then be warmed using the CAC in reverse mode. This procedure conditions the intake air charge to the most desirable temperature and relative humidity across a wider range of environmental and operating conditions. The result is a warm, moist air charge exiting the CAC, providing significant dilution for the combustion engine.

[0034] During humid conditions, a charge cooling effect is provided by cooling charged air as it flows through the CAC (Cooling Air Compensator) operating in cooling mode and by injecting water at a point downstream of the CAC. The evaporation after the CAC cools the air to the dew point of approximately 15°C, even if the air exiting the CAC is at 35°C. Since no heat of vaporization is transferred to the air, the air-water mixture can draw heat of vaporization from the intake manifold, thus enhancing the charge cooling effect provided by the post-CAC injection.

[0035] With reference to Fig. Figure 3 illustrates an exemplary method 300 for injecting water into an internal combustion engine. Water injection can involve injecting water through one or more water injection nozzles of a water injection system, such as the water injection system 60 described in Fig. 1 is shown. Instructions for carrying out procedure 300 and the rest of the procedures contained in this document can be carried out by a controller (such as the controller 12 shown in Fig. 1 is shown), based on instructions stored in a memory of the control unit and in conjunction with signals received from sensors of the internal combustion engine system, such as those mentioned above in relation to Fig. The controller can utilize internal combustion engine actuators to adjust engine operation according to the methods described below. For example, the controller can send a signal to an actuator to inject water into a water injector at a specific point in the engine. This method allows for the injection of water into an internal combustion engine intake manifold at a point upstream or downstream of a CAC, based on sensor feedback, such as from an intake manifold lambda sensor and a knock sensor, to provide the benefits of charge dilution or charge cooling.

[0036] Procedure 300 begins at 302 by estimating and / or measuring the internal combustion engine operating conditions. The estimated internal combustion engine operating conditions may include: manifold absolute pressure (MAP), ambient conditions (ambient temperature, pressure, humidity), exhaust air / fuel mixture (A / F), exhaust gas recirculation (EGR) flow rate, mass airflow (MAF), intake manifold charge temperature (MCT), internal combustion engine speed and / or load, driver torque demand, internal combustion engine temperature, exhaust catalyst temperature, etc.

[0037] The next step in procedure 304 involves determining whether supercharging is required. For example, supercharging may be required in response to the internal combustion engine speed and / or load exceeding a threshold. For instance, the internal combustion engine speed / load may be increased in response to an increase in driver torque demand following a tip-in event.

[0038] When supercharging is required, the method described in 308 involves operating a compressor (e.g., a turbocharger compressor) to provide a target boost pressure. For example, the control system may close an exhaust boost pressure control valve to accelerate turbine spool-up and thus increase the compressor speed. In embodiments where the compressor is coupled to an electric motor (e.g., a forced-air compressor), operating the compressor may involve driving the electric motor to a speed that increases the compressor speed to the target value. The internal combustion engine can then be operated with supercharging.

[0039] The next step in the procedure at 310 involves monitoring the CAC condensate level based on supercharging and internal combustion engine operating conditions. Operating the internal combustion engine under supercharging involves passing compressed and heated air through the CAC to cool it before it is fed to the engine. Therefore, during supercharged operation, the CAC operates in a cooling mode, drawing heat from the air flowing through it, which is then added to the coolant circulating within the CAC. During rapid local cooling, the air temperature can drop below a dew point, causing moisture to condense. At least some of the condensate can be collected in a collection point at the bottom of the CAC.The CAC condensate level can vary depending on the boost pressure, increasing with increasing boost pressure and the duration of turbocharged engine operation. The CAC condensate level can also vary depending on ambient conditions, increasing with increasing ambient humidity. The CAC condensate level can be continuously monitored during turbocharged engine operation and compared to a threshold value above which condensate is unintentionally drawn into the engine, potentially leading to misfires. In response to the CAC condensate level exceeding the threshold, the accumulated condensate can be opportunistically fed back into the engine, for example, during steady-state operation or driving, at a controlled rate.

[0040] In the case of 312, the procedure involves determining whether a knock indication is present. The knock indication can involve detecting an actual knocking event or anticipating knocking based on internal combustion engine operating conditions. The control unit can determine whether knocking occurs based on the output of one or more knock sensors (such as knock sensors 183, as in Fig. (1 shown). In one example, engine knocking can be indicated when the knock sensor output is higher than a knock threshold. In another example, engine knocking can be anticipated when the engine speed and / or load is higher than a threshold, or when the engine's knocking history reflects a high tendency to knock (e.g., knock count higher than threshold). If the engine has a knock limit, water injection can be used to provide charge cooling, which reduces the tendency to further knock.

[0041] If knocking is detected, the procedure continues at 314, determining whether water injection is possible. In one example, water injection might not be possible if no water is available for injection. For instance, water might not be available for water injection if the water level in a water reservoir (such as the one in Fig. 1. Water reservoir 63) shown below a threshold. In another example, water may not be available for injection if one or more of the water temperatures and water quality in the reservoir are unsuitable for injection. In yet another example, water injection may not be possible if the internal combustion engine load is below a threshold or if the ignition timing is retarded by less than a threshold amount. Under such conditions, water injection may cause misfires. If water is not available for injection due to low availability, the control system may increase water collection from within the vehicle. This may include collecting water from onboard systems, such as a water collection system connected to a water reservoir of the internal combustion engine's water injection system.For example, the operation of the vehicle's air conditioning compressor can be adjusted to increase the collection of AC condensate. Another example is adjusting the EGR flow to increase the collection of EGR condensate. Yet another example is increasing the collection of condensate from the vehicle's surface. The collected water can be stored in the water reservoir. In another example, the control unit can send a notification to the driver to manually refill the water reservoir.

[0042] If water injection is not possible on the 314 and 318, the procedure involves retarding the ignition timing to provide knock relief. In response to the knock indication, the control unit can adjust one or more operating conditions of the internal combustion engine to provide knock relief. For example, the control unit can retard the ignition timing (further) from the maximum operating point (MBT), applying the degree of retard based on the knock intensity. In another example, the control unit can additionally or alternatively increase the pulse width of the fuel injected directly into the knocking cylinder to enrich the combustion air-fuel mixture. Furthermore, the control unit can reduce the amount of throttle opening to lower intake manifold pressure.However, if water injection is possible at 316, the procedure involves injecting water into the intake manifold at a point downstream of the CAC (after the CAC). The amount of water injected is based on the knock sensor reading. In one example, the controller can refer to a lookup table stored in its memory, which has the knock sensor output as the input and the requested amount of water injection as the output. In another example, the lookup table can be stored with the engine load as the input and the requested amount of water injection as the output. The controller can send a pulse width signal corresponding to the requested amount to the intake manifold water injection nozzle located downstream of the CAC.If the requested water injection quantity causes the port water injection to exceed a limit, the control unit can adjust the pulse width requested by the port water injection nozzle until the nozzle's water injection limit is reached. Afterward, the remainder of the total requested water quantity can be supplied by direct water injection. Additionally, or optionally, the remainder can be supplied by channel water injection away from an open intake valve, allowing the injected water to be carried in the airflow before reaching the cylinder. In one example, the port water injection limit might be a limit to the nozzle's pulse width. In another example, the port water injection limit might be reached when the nozzle's flow rate reaches a limit.In yet another example, the limit of water injection by the intake manifold injector can be reached when the moisture in the intake manifold near the injector reaches a saturation limit.

[0043] The specified (e.g., requested) amount of water can be supplied to the intake manifold as a single pulse per combustion engine stroke or as a series of pulses, which is synchronized with the opening of the intake valve of each cylinder within the cylinder bank downstream of the injector.

[0044] In further examples, the amount of water injected can be adjusted based on the level of the CAC condensate. The CAC is operated to cool the intake air charge to within a few degrees above the dew point temperature to prevent condensation. After the air exits the CAC, its relative humidity decreases while its specific humidity remains unchanged, allowing more water to be injected at a point downstream of the CAC, up to a relative humidity limit of 100%.

[0045] By introducing water downstream of the CAC in response to knocking during charged conditions, heat of vaporization is drawn from the intake manifold, thereby increasing the charge cooling effect of the water injection.

[0046] If knocking is not detected at step 312, the procedure continues at step 320 and involves determining whether a dilution request exists. For example, dilution may be requested if the internal combustion engine speed / load is low and / or if combustion stability reaches or is close to reaching a limit. The control unit can refer to a lookup table that uses the internal combustion engine speed and load as an input and provides a dilution quantity to be requested as an output. In one example, increased dilution may be requested in response to an internal combustion engine speed / load falling below a threshold, where the engine speed / load threshold may indicate a speed / load range in which pumping losses are more likely to occur.In another example, charge dilution may be requested when the internal combustion engine has reached or is close to reaching the limit of combustion stability. If there is no dilution request at 322, the procedure involves keeping the water injection disabled. Furthermore, at 322, the procedure involves continuing the internal combustion engine operation without injecting water. If there is a dilution request, the procedure continues at 324, which determines whether water injection is possible. As described above with respect to the procedure at 314, water injection may not be possible if water is not available for injection. If water injection is not possible, the procedure continues at 328 to adjust one or more operating parameters of the internal combustion engine to provide the required dilution.This may involve increasing the EGR flow (quantity and rate) by increasing the opening of the EGR valve.

[0047] However, while water injection is possible in 324, in 326 the procedure involves injecting water into the intake manifold, downstream of the CAC (after the CAC), until a limit is reached, and then injecting water into the intake manifold. The control unit can send a signal to an actuator of a water injector nozzle to inject water in a quantity of water via a downstream intake manifold water injector nozzle upstream of a CAC (such as water injector nozzle 44, as in Fig. (1 shown). The injected water quantity is based on the dilution request. In one example, the controller can reference a lookup table stored in its memory, which has a lambda sensor output and / or a requested dilution quantity as the input and the requested water injection quantity as the output. In another example, the lookup table can be stored with the internal combustion engine speed load as the input and the requested water injection quantity as the output. The controller can send a pulse width signal corresponding to the requested quantity to the intake manifold water injector located downstream of the CAC.If the requested water injection quantity causes the intake manifold water injection to exceed a limit, the control system can adjust the pulse width requested by the intake manifold water injection nozzle until the nozzle's water injection limit is reached. In one example, the intake manifold water injection limit might be a pulse width limit for the nozzle. In another example, the intake manifold water injection limit might be reached when the nozzle's flow rate reaches a limit. In yet another example, the intake manifold water injection limit might be reached when the moisture in the intake manifold near the nozzle reaches a saturation point. Afterward, the remainder of the requested total water quantity can be supplied via port injection.For example, in response to a dilution request, the control unit can request water injection from the channel water injectors, which are positioned at an angle to the intake valves, and synchronize the timing of the water injection with the timing of the intake valve so that water is injected onto a hot, closed intake valve. Alternatively, the channel water injectors can be positioned at an angle to the intake valve and configured to inject onto the valve surface and / or the area surrounding the intake manifold surface. By supplying water to the closed intake valve and / or the intake manifold surface in response to the dilution request, the injected water evaporates on the hot internal combustion engine surfaces, thereby increasing the dilution effect of the water injection.Referring again to the procedure in paragraph 304, where no turbocharging is required, the procedure in paragraph 306 involves operating the internal combustion engine with natural intake. Operating with natural intake involves keeping the turbocharger deactivated. For example, turbocharging is not required when the internal combustion engine is idling, or when the engine speed / load is below a certain threshold.

[0048] The next step in the procedure at 330 involves determining whether a dilution requirement exists. If no dilution requirement exists, the procedure continues at 332, determining whether water injection is possible. As described above with respect to the procedure at 314, water injection may not be possible if water is not available for injection. If water injection is not possible, the procedure continues at 334 to adjust one or more operating parameters of the internal combustion engine to provide the required charge dilution, such as by increasing the EGR flow. In one example, adjusting the operating parameters of the internal combustion engine to achieve the required dilution might involve determining an EGR quantity to supply the internal combustion engine.The control unit can refer to a lookup table that uses the internal combustion engine speed and load as an input and provides a required EGR quantity as an output. The control unit can increase the EGR flow (quantity and rate) by increasing the opening of the EGR valve. Consequently, EGR can be used to achieve the required dilution when water injection is unavailable. However, when water injection is possible, the procedure involves injecting water into the intake manifold before or after the CAC (Cooling Air Control). The amount of water injected is based on the required dilution, intake air temperature, and humidity. In one example, the control unit can refer to a lookup table stored in its memory that has the lambda sensor output as the input and the required amount of water injection as the output.In another example, the lookup table can be stored with the internal combustion engine's speed load as the input and the required amount of water injection as the output. The controller can send a pulse width signal corresponding to the requested quantity to the intake manifold water injection nozzle. In this way, water injection via an intake manifold injection nozzle located upstream or downstream of a CAC (Cooling Air Control) can be used to meet a dilution requirement of an internal combustion engine under vacuum conditions.

[0049] If there is no dilution request at 330, the procedure continues at 340 to determine whether knock is detected. As discussed previously, knock indication can involve detecting an actual knocking event or anticipating knocking based on internal combustion engine operating conditions. The controller can determine whether knocking is occurring based on the output from one or more knock sensors (such as knock sensors 183, as shown in Fig. (1 shown). In one example, internal combustion engine knock can be indicated when the knock sensor output is higher than a knock threshold. In another example, internal combustion engine knock can be anticipated when the engine speed and / or load is higher than a threshold, or when the engine's knock history reflects a high tendency to knock (e.g., knock number higher than threshold). If the internal combustion engine has a knock limit, water injection can be used to provide charge cooling, which reduces the tendency to further knock. If no knock is detected, the procedure at 342 involves keeping water injection disabled. However, if knock is detected, the procedure at 344 involves determining whether water injection is possible.In one example, water injection may not be possible if no water is available for injection. As described above with respect to the procedure at 314, water injection may not be possible if water is not available for injection. If water injection is not possible, the procedure continues with 348 to retard the ignition timing. In response to the knock indication, the control can adjust one or more operating conditions of the internal combustion engine to provide knock relief. For example, the control can retard the ignition timing (further) from the MBT, applying the degree of ignition retard based on the knock intensity.In another example, the control system can additionally or alternatively increase the pulse width of the fuel injected directly into the knocking cylinder to enrich the combustion air-fuel mixture. Furthermore, the control system can reduce the throttle valve opening to lower the intake manifold pressure.

[0050] However, if water injection is possible at 346, the procedure involves injecting water into the intake manifold at a point downstream of the CAC (after the CAC) until a limit is reached, and then injecting water directly. As described above with respect to the procedure at 316, the amount of water injected is based on the knock indication. In one example, the controller can refer to a lookup table stored in the controller's memory, which has the knock sensor output as the input and the amount of water to be injected as the output. In another example, the lookup table can be stored with the engine speed load as the input and the amount of water to be injected as the output. The controller can send a pulse width signal corresponding to the requested amount to the intake manifold water injector located downstream of the CAC.If the requested water injection quantity causes the port water injection to exceed a limit, the control unit can adjust the pulse width requested by the port water injection nozzle until the nozzle's limit is reached. Afterward, the remainder of the total requested water quantity can be supplied by direct water injection. Additionally, or optionally, the remainder of the total requested water quantity can be supplied by port water injection from an open intake valve to increase water carryover in the airflow, thus enhancing the charge cooling benefit of port injection. In one example, the port water injection limit could include a pulse width limit for the nozzle.In another example, the limit of water injection from the intake manifold injector may be reached when the injector's flow rate reaches a certain limit. In yet another example, the limit of water injection from the intake manifold injector may be reached when the moisture content in the intake manifold near the injector reaches a saturation point. The specified (e.g., requested) amount of water can be introduced into the intake manifold as a single pulse per combustion engine cycle or as a series of pulses synchronized with the opening of the intake valve of each cylinder within the cylinder bank downstream of the injector. In still other examples, the amount of water injected can be adjusted based on the level of the CAC condensate.By introducing water downstream of the CAC in response to knocking during charged conditions, heat of vaporization is drawn from the intake manifold, thereby increasing the charge cooling effect of the water injection.

[0051] In this way, an internal combustion engine control unit can inject a larger proportion of water upstream than downstream of an intercooler while the intercooler is operating in a heating mode, and a larger proportion of water downstream than upstream of the intercooler while the intercooler is operating in a cooling mode. Injecting a larger proportion upstream than downstream of the intercooler involves determining a total amount of water to inject into the internal combustion engine based on the engine's operating conditions, and then supplying a larger proportion of that determined total amount of water to a location upstream of the intercooler (such as through a port water injector), while a remaining, smaller proportion of that determined total amount of water is supplied to a location downstream of the intercooler (such as through a channel or direct water injector).At this point, the CAC operates in heating mode, with the larger proportion of injected water being heated by heat transfer from a circulating coolant (into the water). Consequently, more water evaporates by the time it reaches the internal combustion engine, allowing for greater charge dilution. In comparison, injecting a larger proportion of water downstream than upstream of the charge air cooler involves determining a total amount of water to inject into the internal combustion engine based on the engine's operating conditions, and then supplying a larger proportion of that determined total amount of water to a location downstream of the CAC (such as through a channel or direct water injector), while a remaining, smaller proportion is supplied to a location upstream of the CAC (such as through a port water injector).At this point, the CAC operates in cooling mode, transferring heat from the charge air flowing through the CAC to the circulating coolant. This increases the amount of water reaching the internal combustion engine in liquid form, thus enabling further charge cooling. In each case, the allocation of the total amount of water is determined based on the operating conditions of the internal combustion engine (such as the presence or absence of boost pressure, ambient temperature and humidity, etc.) and further based on the dilution requirement of the internal combustion engine relative to its charge air cooling requirement. Fig.Figure 4 illustrates exemplary adjustments to water injection and internal combustion engine operation based on ambient humidity and temperature. For example, Figure 400 illustrates adjustments to water injection from an intake manifold water injector located upstream or downstream of a CAC (Coolant Adjustment Control Unit). Specifically, the operating parameters illustrated in Figure 400 show changes in internal combustion engine speed at curve 402, changes in manifold absolute pressure (MAP) at curve 404, the amount of water injected by an upstream water injector at curve 406, the amount of water injected by a downstream water injector at curve 408, changes in ambient humidity at curve 410, changes in ambient temperature at curve 412, changes in ignition timing at curve 414, and changes in EGR (Exhaust Gas Recirculation) flow at curve 416.For each operating parameter, time is illustrated along a horizontal axis, and values ​​of all respective operating parameters are illustrated along the vertical axes.

[0052] Before time t1, the combustion engine operates with natural intake because the engine speed and / or load is below a threshold value (curve 402). At this time, water injection is not required.

[0053] At time t1, the internal combustion engine's speed / load increases due to an increase in torque demand. However, turbocharged operation is not required, so the engine continues to operate with natural intake. Due to the shift from low to medium load conditions, the engine's dilution requirement increases. Since the conditions for water injection are met and water is available, water is injected into the engine based on this dilution requirement. In response to relatively low ambient temperature (curve 412) and humidity (curve 410), the controller injects water at time t1 through a water injection nozzle upstream of the CAC (curve 406). The controller can determine the amount of water to be injected based on the engine's dilution requirement.During this time, the CAC operates in a heating mode, and heat is transferred from the coolant flowing through the CAC into the air charge. Consequently, the temperature and humidity of the air increase, thus enhancing the charge dilution effect of the water injection.

[0054] At time t2, the driver torque demand increases again. However, the internal combustion engine remains in the mid-load range, and turbocharged operation is not required. A further increase in the dilution demand occurs. However, at t2, the water injector upstream of the CAC is at its upper limit and cannot provide any further dilution. In response to the increased dilution demand, the control unit adjusts one or more other operating parameters of the internal combustion engine to address the dilution demand. In the illustrated example, the control unit increases the EGR flow (curve 416) while maintaining the water injection upstream of the CAC at its limit after time t2 to achieve the desired dilution demand.Alternatively, as shown in the dashed area 407, the control unit can inject water at a point downstream of the CAC while simultaneously maintaining the upstream water injection at the limit value. In this document, the injection downstream of the CAC can involve channel water injection onto a closed, hot inlet valve.

[0055] At time t3, the internal combustion engine speed / load increases further due to an increase in torque demand. Because of this increased load, turbocharged operation is required, and the turbocharger / compressor output is increased to provide the desired boost pressure. As a result of the turbocharged operation, MAP (curve 404) increases. Additionally, the control unit deactivates water injection from the water injector upstream of the CAC and reduces the EGR flow in response to a decreased dilution requirement.

[0056] Between times t3 and t4, the engine speed and / or load (curve 402) increase due to an increase in torque demand. The engine is also operating under turbocharged conditions (curve 404). The conditions for water injection are not met because the engine is not knock-limited. Therefore, the control unit keeps water injection deactivated (curves 406 and 408). Additionally, the ambient humidity (curve 410) and ambient temperature (curve 412) increase. In one example, the ambient temperature and humidity could increase as a result of driving the vehicle to a location with higher ambient temperature and humidity. In another example, the ambient temperature and humidity could increase if current weather conditions change, such as due to the onset of rain.

[0057] At time t4, due to a further increase in the internal combustion engine's speed / load resulting from an increase in driver torque demand (such as a tip-in to widen the throttle), the engine's knock limiter is activated. For example, engine knock is detected. At this point, because the engine is turbocharged and both ambient temperature and humidity are relatively high, the control unit injects water into the engine at a point downstream of the CAC (Cooling Air Control Unit), such as through the intake manifold water injector downstream of the CAC. During this time, the CAC operates in cooling mode. Operating the CAC in cooling mode transfers heat from the intake air to the coolant, thereby reducing the intake air temperature.Consequently, a larger fraction of the water injected downstream of the CAC can evaporate locally, thereby increasing local charge cooling and reducing the tendency to knock.

[0058] Then, at time t5, the water injection from the water injector downstream of the CAC reaches an upper limit (curve 408). However, knock relief is still required. In response to the water injection downstream of the CAC reaching its upper limit, the control unit maintains the intake manifold water injection downstream of the CAC at its limit and adjusts one or more other operating parameters of the internal combustion engine to address knocking. In the illustrated example, the control unit increases the amount of MBT ignition timing retard in response to knocking (curve 414). As such, the applied amount of ignition timing retard is less than the ignition timing retard that would have been required if no water had been injected (as illustrated by the dashed segment 413). Therefore, using water injection to address knocking improves fuel economy.In an alternative example, where the internal combustion engine is configured with direct water injection, the control unit can inject water through direct water injectors instead of retarding the ignition timing. This occurs because the intake manifold water injector after the CAC is operating at its upper limit to provide the benefit of additional charge cooling. As a result of the water injection and the ignition timing adjustments, knocking decreases until time t6. Since knocking is addressed at t6 and the engine's speed load decreases (due to decreasing driver demand), knock relief is no longer necessary. Therefore, the control unit disables the water injection (curve 408) and advances the ignition timing to MBT at time t6 (curve 414).

[0059] In this way, the charge dilution benefit of water injection during dry or cold ambient conditions can be increased by injecting water upstream of an intercooler while the internal combustion engine is running naturally aspirated. The technical effect of heat transfer from the coolant circulating through the CAC to the air charge flowing through the CAC is that the water is carried more effectively into the air, allowing warm, moist air to be supplied to the internal combustion engine. The warm, moist air generated by heat transfer to the air in the CAC enhances the water dilution effect, thereby reducing the pumping work and exhaust NOx emissions from the internal combustion engine. The charge cooling benefit of water injection during humid or warm ambient conditions can be increased by injecting water downstream of the intercooler while the internal combustion engine is running with turbocharging.The technical effect of drawing heat from the air charge, which flows through the CAC (Cooling Air Control) into the coolant circulating through the CAC, is a potential lowering of the air charge's dew point. This allows more water to be available in liquid form at the intake manifold. At the intake manifold, the water can evaporate by drawing heat from the surrounding air, increasing the water's cooling effect and reducing knocking tendency. By improving water utilization, the benefits of water injection can be extended across a wider range of internal combustion engine operating conditions. Overall, this results in improved internal combustion engine performance and fuel economy.

[0060] In one embodiment, a method includes injecting a larger proportion of water upstream of an intercooler while the intercooler is operating in a heating mode; and injecting a larger proportion of water downstream of the intercooler while the intercooler is operating in a cooling mode. In a first example of the method, the method further includes the injection of water upstream of the intercooler responding to an ambient temperature below a threshold, and the injection of water downstream of the intercooler responding to an ambient temperature above the threshold.A second example of the method optionally includes the first example and further includes, wherein the injection of water upstream of the charge air cooler responds to ambient humidity falling below a threshold, and the injection of water downstream of the charge air cooler responds to ambient humidity exceeding the threshold. A third example of the method optionally includes one or more of the first and second examples and further includes, wherein operating the cooler in heating mode involves operating the internal combustion engine with natural intake, and wherein operating the cooler in cooling mode involves supercharged operation of the internal combustion engine.A fourth example of the method optionally includes one or more of the first three examples, and further includes, wherein the injection of water upstream of the charge air cooler responds to a dilution requirement of the internal combustion engine, and the injection of water downstream of the charge air cooler responds to a cooling requirement of the internal combustion engine. A fifth example of the method optionally includes the first four examples, and further includes, wherein an amount of water injected upstream of the charge air cooler is based on each of the dilution requirement of the internal combustion engine, intake manifold pressure, and ambient temperature, and wherein the amount of water injected downstream of the charge air cooler is based on each of the internal combustion engine cooling requirement, a boost pressure, and a charge air cooler condensate level.A sixth example of the method optionally includes the first five examples and further includes, wherein operating the cooler in heating mode involves transferring heat from a coolant circulating through the heat exchanger to air flowing through the heat exchanger, and wherein operating the cooler in cooling mode involves transferring heat from the air flowing through the heat exchanger to the coolant circulating through the heat exchanger. A seventh example of the method optionally includes the first six examples and further includes, wherein an air temperature at an outlet of the charge air cooler is at a (common) temperature setting when the cooler is operated in both heating and cooling modes, the temperature setting being selected based on a knock limit of the internal combustion engine.An eighth example of the method optionally includes the first through seventh examples and further comprises adjusting a first set of operating parameters of the internal combustion engine that respond to the injection of water upstream of the charge air cooler, and adjusting a second, different set of operating parameters of the internal combustion engine that respond to the injection of water downstream of the charge air cooler. A ninth example of the method optionally includes the first through eighth examples and further comprises, wherein the first set of operating parameters of the internal combustion engine includes an EGR flow rate, and wherein the second set of operating parameters of the internal combustion engine includes ignition timing adjustment.

[0061] In a further embodiment, a method comprises, during a first condition when both ambient temperature and humidity are lower, injecting water upstream of an intercooler to increase the temperature and humidity of the charge supplied to the internal combustion engine; and during a second condition when both ambient temperature and humidity are higher, injecting water downstream of the intercooler to lower the temperature of the charge supplied to the internal combustion engine. In a first example of the method, the method further includes, wherein during the first condition the internal combustion engine operates with natural intake, and wherein during the second condition the internal combustion engine operates with forced induction.A second example of the method optionally includes the first example and further includes, wherein during the first condition the internal combustion engine is dilution-limited and the amount of water injected upstream of the charge air cooler is based on the dilution requirement of the internal combustion engine and the intake manifold pressure, and wherein during the second condition the internal combustion engine is knock-limited and the amount of water injected downstream of the charge air cooler is based on an internal combustion engine knock limit and boost pressure. A third example of the method optionally includes one or more of the first and second examples and further includes, wherein during both the first and second conditions the amount of water injected is also based on a condensate level at the charge air cooler.A fourth example of the method optionally includes the first three examples and further comprises, during the first condition, adjusting the opening of an EGR valve based on the amount of water injected upstream of the charge air cooler, and during the second condition, adjusting the ignition timing based on the amount of water injected downstream of the charge air cooler. A fifth example of the method optionally includes the first four examples and further comprises, during both the first and second conditions, the flow of air through the charge air cooler and the circulation of a coolant coupled to an internal combustion engine coolant system through the charge air cooler, with heat being transferred from the coolant to the air during the first condition and from the air to the coolant during the second condition.A sixth example of the method optionally includes the first to fifth examples, and further comprises, while both the first and second conditions are met, maintaining a temperature of the air exiting the charge air cooler at a setpoint temperature, the setpoint temperature being selected as a function of a knock limit of the internal combustion engine when operating with a turbocharger.

[0062] In yet another embodiment, a system includes an internal combustion engine; a compressor to provide a supercharged air charge to the internal combustion engine; an intercooler coupled downstream of the compressor; a coolant system for coolant circulating through the intercooler and the internal combustion engine; a first water injector coupled upstream of the intercooler and downstream of the compressor; a second water injector coupled downstream of the intercooler; an EGR channel, including an EGR valve, for exhaust gas recirculation from an exhaust manifold to an intake manifold, upstream of the compressor; a humidity sensor coupled to the intake manifold upstream of the compressor to estimate ambient humidity; and a temperature sensor coupled to the intake manifold upstream of the compressor to estimate ambient temperature.and a control system with computer-readable instructions to: in response to the ambient temperature falling below a temperature threshold, inject more water into the combustion engine upstream of the charge air cooler than downstream of the charge air cooler, while the compressor remains deactivated;and in response to the ambient temperature exceeding the temperature threshold, injecting more water into the combustion engine downstream of the charge air cooler than upstream of the charge air cooler while the compressor is activated. In a first example of the system, the system further includes increasing the proportion of the total water injection quantity injected upstream of the charge air cooler as the ambient temperature decreases, and decreasing the proportion of the total water injection quantity injected downstream of the charge air cooler as the ambient temperature increases. A second example of the system optionally includes the first example and further includes the control further including instructions to: reduce the opening of the EGR valve in response to the proportion of water injected upstream of the charge air cooler;and to advance the ignition timing in response to the amount of water injected downstream of the charge air cooler.

[0063] It should be noted that the example control and estimation routines contained in this document can be used with various internal combustion engine and / or vehicle system configurations. The control methods and routines disclosed in this document can be stored as executable instructions in non-volatile memory and can be executed by the control system, including the controller, in combination with the various sensors, actuators, and other internal combustion engine hardware. The specific routines described in this document can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, various illustrated actions, operations, and / or functions can be executed in parallel in the illustrated sequence or, in some cases, omitted.Likewise, the processing sequence is not strictly necessary to achieve the features and advantages of the embodiments described in this document, but it is provided for the sake of simplicity. One or more of the illustrated actions, processes, and / or functions can be performed repeatedly, depending on the strategy employed. Furthermore, the described actions, processes, and / or functions can represent code in diagram form that is to be programmed into the non-volatile memory of the computer-readable storage medium in the internal combustion engine's control system, with the described actions being carried out by executing the instructions in a system that includes the various hardware components of the internal combustion engine in conjunction with the electronic control unit.

[0064] It is understood that the configurations and routines disclosed in this document are exemplary and that these specific embodiments are not to be understood as limiting, since numerous variations are possible. For example, the aforementioned technology can be applied to V-6, I-4, I-6, and V-12 engines as opposed to 4-cylinder and other internal combustion engine types. The subject matter of this disclosure includes all innovative and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0065] The following claims specifically identify certain combinations and subcombinations that are considered innovative and not obvious. These claims may refer to "one" element or "a first" element, or its equivalent. Such claims are to be understood as including one or more such elements, and do not require or exclude two or more of these elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by filing new claims in this or a related application. Such claims, whether their scope is broader, narrower, the same, or different from that of the original claims, are also to be considered as included in the subject matter of these disclosures.

Claims

[1] Method for an internal combustion engine, comprising: Injecting a larger proportion of water upstream than downstream of an intercooler while the cooler is operating in a heating mode; and Injecting a larger proportion of water downstream than upstream of the charge air cooler while the cooler is operating in a cooling mode. [2] Method according to claim 1, wherein the injection of a larger quantity of water upstream of the charge air cooler reacts to an ambient temperature below a threshold value, and the injection of a larger quantity of water downstream of the charge air cooler reacts to an ambient temperature above the threshold value. [3] Method according to claim 1, wherein the injection of a larger quantity of water upstream of the charge air cooler reacts to the fact that the ambient humidity is below a threshold value, and the injection of a larger quantity of water downstream of the charge air cooler reacts to the fact that the ambient humidity is above the threshold value. [4] Method according to claim 1, wherein operating the cooler in heating mode includes operating the internal combustion engine with natural intake, and wherein operating the cooler in cooling mode includes supercharged operation of the internal combustion engine. [5] Method according to claim 4, wherein the injection of a larger quantity of water upstream of the charge air cooler responds to a dilution requirement of the combustion mode, and the injection of a larger quantity of water downstream of the charge air cooler responds to a cooling requirement of the internal combustion engine. [6] Method according to claim 5, wherein the amount of water injected upstream of the charge air cooler is based on each of the dilution requirement of the internal combustion engine, intake manifold pressure and ambient temperature, and wherein the amount of water injected downstream of the charge air cooler is based on each of the internal combustion engine cooling requirement, a boost pressure and a charge air cooler condensate level. [7] Method according to claim 1, wherein operating the cooler in heating mode includes transferring heat from a coolant circulating through the heat exchanger to air flowing through the heat exchanger, and wherein operating the cooler in cooling mode includes transferring heat from the coolant circulating through the heat exchanger to the coolant circulating through the heat exchanger. [8] Method according to claim 1, wherein an air temperature at an outlet of the charge air cooler is at a (common) temperature setting during operation of the cooler in both heating mode and cooling mode, wherein the temperature setting is selected based on a knock limit of the internal combustion engine. [9] Method according to claim 1, further comprising adjusting a first set of operating parameters of the internal combustion engine that respond to the injection of water upstream of the charge air cooler, and adjusting a second, different set of operating parameters of the internal combustion engine that respond to the injection of water downstream of the charge air cooler. [10] Method according to claim 9, wherein the first set of operating parameters of the internal combustion engine includes an EGR flow rate, and wherein the second set of operating parameters of the internal combustion engine includes ignition timing adjustment. [11] Internal combustion engine system, comprising: an internal combustion engine; a compressor to provide the internal combustion engine with a supercharged air supply; a charge air cooler coupled downstream of the compressor; a coolant system for coolant circulating through the charge air cooler and the internal combustion engine; a first water injection nozzle coupled upstream of the charge air cooler and downstream of the compressor; a second water injection nozzle coupled downstream of the charge air cooler; an EGR channel including an EGR valve for recirculating exhaust gas from an exhaust manifold to an intake manifold upstream of the compressor; a humidity sensor coupled upstream of the compressor to the intake manifold for estimating ambient humidity; a temperature sensor coupled upstream of the compressor to the intake manifold for estimating an ambient temperature; and a control system with computer-readable instructions, In response to the ambient temperature falling below a threshold, more water is injected into the combustion engine upstream of the charge air cooler than downstream of the charge air cooler, while the compressor remains deactivated; and In response to the ambient temperature exceeding the temperature threshold, more water is injected into the combustion engine downstream of the charge air cooler than upstream of the charge air cooler while the compressor is activated. [12] System according to claim 11, wherein a fraction of the total water injection quantity injected upstream of the charge air cooler is increased with decreasing ambient temperature, and wherein the fraction of the total water injection quantity injected downstream of the charge air cooler is reduced with increasing ambient temperature. [13] System according to claim 12, wherein the control further includes instructions to: to reduce the opening of the EGR valve in response to the amount of water injected upstream of the charge air cooler; and to advance the ignition timing in response to the amount of water injected downstream of the charge air cooler.

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