Method and system for engine water injection

Abstract

Method for an engine, comprising: Predicting an expected injection error for a water injection system that delivers water to the engine based on water quality in a water storage tank; Estimating an actual injection error based on a change in engine parameters during the rise of water injection; and Adjusting water injection into the engine based on either the expected injection error or the actual injection error.

Description

AREA

[0001] This description generally relates to methods and systems for controlling the quality of water injected into an engine. GENERAL STATE OF THE ART / SUMMARY

[0002] Internal combustion engines may incorporate water injection systems that inject water into a variety of locations, such as into an intake manifold, upstream of engine cylinders, or directly into engine cylinders. Water injection in engines provides several benefits, including increased fuel efficiency and engine power, as well as reduced engine emissions. In particular, when water is injected into the engine intake or cylinders, heat is transferred from the intake air and / or engine components to the water, resulting in charge cooling. Injecting water into the intake air (e.g., into the intake manifold) lowers both the intake air temperature and the combustion temperature in the engine cylinders. By cooling the intake air charge, knocking can be reduced without enriching the combustion air-fuel ratio.This can also enable a higher compression ratio, advanced ignition timing, improved wide-throttle performance, and reduced exhaust temperature. As a result, fuel efficiency is increased. Furthermore, a higher volumetric efficiency can lead to increased torque. Furthermore, a lower combustion temperature with water injection can reduce NOx emissions, while a more efficient fuel mixture (less enrichment) can reduce carbon monoxide and hydrocarbon emissions.

[0003] Water injection systems include a water reservoir that can be refilled both manually and opportunistically using water generated internally within the vehicle. For example, water can be collected in the form of condensate from one or more components, such as an EGR cooler, an air conditioning evaporator, an exhaust gas heat exchanger, an intercooler, a vehicle exterior surface, etc. However, the water quality injected into the engine can vary depending on the water source, affecting engine performance and potentially clogging the injection system.

[0004] Various approaches have been developed to test the flow of a water injection system. For example, the tests can determine whether the flow valve solenoids are energized, whether the injection system is clogged, etc. An exemplary approach is shown by Payling et al. in US Pat. No. 6,553,753 B1. In this approach, a flow rate is varied and a flow error is determined based on a difference between the supplied flow and the requested flow. Based on the determined flow error, a water injection system shutoff valve is energized.

[0005] Similarly, document DE 10 2014 222 474 A1 also shows an injection system in which the knock intensity in the cylinder is detected by means of a knock sensor and a fluid admixture in the cylinder is adjusted depending on the detected knock intensity.

[0006] However, the inventors of the present invention have recognized potential problems with such an approach. As one example, the flow error may vary during engine conditions where water injection is applied. For example, small flow errors during partial throttle injection may not correspond to clogging of the water injection system, however, the same error size may correspond to a higher degree of clogging during knock-limited engine operating conditions. Additionally, the small flow errors may have greater impacts on engine performance during knock-limited engine operating conditions or during catalyst cooldown conditions. As another example, contaminants in the water may contribute to flow errors that cannot be reliably distinguished from flow errors due to component problems.The type of contaminants present in the water, as well as the degree of contamination, can vary greatly depending on where the operator refilled the water tank. For example, it may be recommended to refill the water tank with distilled water, but the operator may instead refill with tap or well water. This variation can lead to mineral deposits on water filters, water injectors, engine parts, exhaust catalysts, etc. As another example, relying on a single test to determine whether the water injection system is functioning can be prone to error due to the fact that the test must reliably detect relatively small changes in sensor data. Thus, a more robust functional test may be desired.

[0007] The present invention is therefore based on the object of creating an improved method for an engine and an improved vehicle system that avoids disadvantages of the prior art and advantageously develops the latter. In particular, water injection is to be improved and flow errors are to be better avoided.

[0008] According to the invention, the stated object is achieved by a method according to claim 1 and a vehicle system according to claim 11. Preferred embodiments of the invention are the subject of the dependent claims.

[0009] A method for an engine in a vehicle is proposed, comprising: predicting an expected injection error for a water injection system that delivers water to the engine based on water quality in a water reservoir; if possible, estimating an actual injection error based on a change in engine parameters during the ramp-up of water injection; and adjusting water injection into the engine based either on the actual injection error (if available) or on the expected injection error. In this way, a water injection system can be reliably self-tested in-vehicle, and the amount of injected water can be precisely controlled, even in the presence of partial clogging.

[0010] As one example, a vehicle's water tank may be refilled with water received from a remote location and / or with water collected during vehicle engine operation. The water may be injected during engine operation to utilize the charge cooling properties of water. After refilling the water tank, a quality (e.g., purity or usability) of the water may be assessed based on one or more properties of the water, such as conductivity, turbidity, particulate matter content, etc. Based on the estimated water quality and the amount of time the system is exposed to this water, a probability of clogging in a system that delivers water from the tank to the engine may be predicted. Thus, clogging may lead to a water injection failure.Thus, an expected water injection error associated with the predicted probability of clogging can be determined and used as an initial estimate until the actual extent of the clogging or injection error can be determined. If conditions permit a self-test, an actual injection error can then be determined based on a change in a set of engine operating parameters during water injection ramp-up. The set of engine operating parameters can be selected based on the engine operating conditions at the time of water injection ramp-up. For example, the actual injection error can be determined based on a change in spark retardation necessary to counteract knock when performing the ramp-up under high engine speed and high load conditions.Based on the actual error relative to the predicted error, subsequent water injection (e.g., timing, amount, and location of injection) into the engine can be adjusted. For example, water injection can be adjusted feedforward based on the predicted error and then adjusted feedforward based on the actual error. Furthermore, a water injection window can be selected that better accommodates the extent and type of impurities in the water.

[0011] In this way, the flow of a water injection system can be reliably self-tested. The technical effect of determining a water injection fault based on different sets of engine operating parameters under different engine operating conditions is that even small changes in sensor data can be reliably measured, thereby reducing errors in test results. Furthermore, a more robust self-test with a reduced need for dedicated sensors is possible. By correlating water quality with water injection faults, water quality can be reliably assessed. Furthermore, system damage caused by contaminated water is reduced, and blind losses and the financial burden of water purification are minimized.The technical effect of integrating the water injection system into a control system that protects against the use of contaminated water is to reduce the need for continuous refilling of a water reservoir with contaminated water, extending the lifespan of engine components. By improving water utilization, the benefits of water injection can be extended.

[0012] It should be understood that the foregoing summary is provided to introduce, in a simplified form, a selection of concepts that are 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 solve disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic diagram of an engine system that includes a water injection system. Fig. 2 shows a high-level flowchart for reliable self-testing of the water injection system from Fig. 1. Fig. Figure 3 shows a high-level flowchart for detecting a water injection fault during increasing water injection into an engine. Fig. Figure 4 shows an example water line self-test and water usage settings based on the self-test results. DETAILED DESCRIPTION

[0013] The following description relates to systems and methods for improving the diagnosis of a water injection system coupled to a vehicle engine, as described with reference to the vehicle system of Fig. 1. A controller may be configured to execute a control routine, such as the example routine from Fig. 2, to test the degree of clogging in a water line yourself, connect a water tank to the engine after refilling the tank from an external source or inside the vehicle. As in Fig. 3, the clogging may be determined based on the deviation of an actual water injection error from an expected water injection error, where the actual error may be estimated based on a change in a defined set of engine operating parameters while water injection is ramped up. An exemplary self-test and corresponding water injection settings are described with reference to Fig. 4. In this way, an engine water injection system can be reliably diagnosed and treated to enable significant fuel efficiency improvements for vehicle performance.

[0014] Fig. 1 shows an exemplary embodiment of an engine system 100 configured with a water injection system 60. The engine system 100 is coupled within the motor vehicle 102, illustrated schematically. The engine system 100 includes an engine 10, depicted herein as a boosted engine, coupled to a turbocharger 13 including a compressor 14 driven by a turbine 116. In particular, fresh air is introduced into the engine 10 along the intake passage 142 via the air cleaner 31 and flows to the compressor 14. The compressor may be a suitable intake air compressor, such as an engine-driven or driveshaft-driven supercharging compressor. In engine system 100, the compressor is shown as a turbocharger compressor that is mechanically coupled to turbine 116 by a shaft 19, with turbine 116 being driven by expanding engine exhaust gases.In one embodiment, the compressor and turbine may be coupled in a twin-scroll turbocharger. In another embodiment, the turbocharger may be a variable turbine geometry (VGT) turbocharger, where the turbine geometry is actively varied as a function of engine speed and other operating conditions.

[0015] As in Fig. 1, the compressor 14 is coupled to the throttle valve (e.g., the intake throttle) 20 through the charge air cooler (CAC) 118. The CAC may be, for example, an air-to-air or air-to-coolant heat exchanger. The throttle valve 20 is connected to the engine intake manifold 122. From the compressor 14, the hot compressed air charge enters the inlet of the CAC 118, cools as it flows through the CAC, and then exits to pass through the throttle valve 20 to the intake manifold 122. 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 absolute pressure (MAP) sensor 124, and boost pressure is sensed by the boost pressure sensor 24. A compressor bypass valve (not shown) may be connected in series between the inlet and outlet of the compressor 14. The compressor bypass valve may be a normally closed valve configured to open under selected operating conditions to vent excess boost pressure. For example, the compressor bypass valve may be opened in response to compressor surge.

[0016] The intake manifold 122 is connected to a set of combustion chambers or cylinders 180 through a set of intake valves (not shown) and intake manifolds (e.g., intake ports) 185. As shown in Fig. 1, the intake manifold 122 is located upstream of all combustion chambers 180 of the engine 10. Additional sensors, such as the manifold charge temperature (MCT) sensor 23 and the air charge temperature (ACT) sensor 25, may be included to determine the temperature of the intake air at the respective locations in the intake passage. The air temperature may further be used in conjunction with an engine coolant temperature to, for example, calculate the amount of fuel delivered to the engine. Each combustion chamber may 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 may be connected to selected locations of the engine block.

[0017] The combustion chambers are further connected to the exhaust manifold 136 by means of a set of exhaust valves (not shown). The combustion chambers 180 are covered by the cylinder head 182 and are coupled to fuel injectors 179 (while in Fig. 1, each combustion chamber includes a fuel injector associated therewith. Fuel may be delivered to the fuel injector 179 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. The fuel injector 179 may 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.

[0018] In the illustrated embodiment, a single exhaust manifold 136 is shown. However, in other embodiments, the exhaust manifold may include a plurality of exhaust manifold sections. Designs including a plurality of exhaust manifold sections may allow wastewater from different combustion chambers to be directed to different locations in the engine system. A wideband lambda (Universal Exhaust Gas Oxygen - UEGO) sensor 126 is shown connected to the exhaust manifold 136, which is upstream of the turbine 116. Alternatively, the UEGO sensor 126 may be replaced with a binary lambda sensor.

[0019] As in Fig. 1, exhaust gas is directed from one or more exhaust manifold sections to the turbine 116 to drive the turbine. If reduced turbine torque is desired, some exhaust gas may instead be directed through a wastegate (not shown), thereby bypassing the turbine. The combined flow from the turbine and wastegate then flows through the emissions control device 170. Generally, 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.

[0020] The treated exhaust gas from the emission control device 170 may be exhausted, in whole or in part, to the atmosphere via the exhaust pipe 35. However, depending on operating conditions, some exhaust gas may instead be diverted to an exhaust gas recirculation (EGR) passage 151, through the EGR cooler 50 and the EGR valve 152, to the inlet of the compressor 14. In this way, the compressor is configured to receive exhaust gas taken downstream of a turbine 116. The EGR valve 152 may be opened to receive a controlled amount of cooled exhaust gas to the compressor inlet for desirable combustion and emission control performance. In this way, the engine system 100 is adapted to provide external low-pressure (LP) EGR. The rotation of the compressor in addition to the relatively long LP EGR flow path in the engine system 100 provides excellent homogenization of the exhaust gas into the intake air charge.Furthermore, the arrangement of the EGR takeoff and mixing points provides effective cooling of the exhaust gas for increased available EGR mass and enhanced power. In other embodiments, the EGR system may be a high-pressure EGR system with an EGR passage 151 connecting locations upstream of the turbine 116 to locations downstream of the compressor 14. In some embodiments, the MCT sensor 23 may be positioned to determine the distributor charge temperature and may include recirculated air and recirculated exhaust gas through the EGR passage 151.

[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 may be injected into the engine intake through one or more water injectors 45-48 or directly into the combustion chambers 180. As one example, water may be injected into the intake manifold 122 upstream of the throttle 20 via the water injector 45, also referred to herein as a central water injector. As another example, water may be injected into the intake manifold 122 downstream of the throttle at one or more locations via the water injector 46. As yet another example, water may be injected into one or more intake manifolds (e.g.,Intake ports) 185 by means of the water injector 48 (also referred to herein as port water injection) and / or directly into the combustion chamber 180 by means of the water injector 47 (also referred to herein as direct water injection). In one embodiment, the injector 48 disposed in the intake manifolds may be angled toward and facing the intake valve of the cylinder to which the intake manifold is attached. As a result, the injector 48 may inject water directly onto the intake valve, resulting in faster vaporization of the injected water and a greater dilution benefit from the water vapor. In another embodiment, the injector 48 may be angled away from the intake valve and disposed to inject water against the intake airflow direction through the intake manifold.As a result, more injected water can be carried in the airflow, increasing the charge cooling benefit of water injection.

[0022] Although in Fig. 1, only one representative injector 47 and one injector 48 are shown, each combustion chamber 180 and each intake manifold 185 may include its own injector. In alternative embodiments, the water injection system 60 may include water injectors positioned at one or more of these locations. For example, in one embodiment, the engine may include only the water injector 46. In another embodiment, the engine may include each of the water injector 46, the water injectors 48 (one at each intake manifold), and the water injectors 47 (one at each combustion chamber).

[0023] The water injection system 60 may include a water storage tank 63, a water lift pump 162, a collection system 72, and a water fill channel 69. Water stored in the water tank 63 is delivered to the water injection devices 45-48 via the water channel 61 and piping or lines 161. In embodiments including multiple injection devices, the water channel 61 may include a valve 162 (e.g., a switching valve, multi-port valve, proportional valve, etc.) to direct water to the various water injection devices via the corresponding lines. Alternatively, each piping (or water line) 161 may include corresponding valves within the water injection devices 45-48 for adjusting the water flow therethrough.In addition to the water lift pump 162, one or more additional pumps may be provided in the lines 161 to pressurize the water directed to the injectors, such as in the line coupled to the direct water injection device 47.

[0024] The water storage tank 63 may include a water level sensor 65 and a water temperature sensor 67, which may communicate information related to water conditions to the controller 12. For example, during freezing conditions, the water temperature sensor 67 detects whether the water in the tank 63 is frozen or available for injection. In some embodiments, an engine coolant passage (not shown) may be thermally coupled to the storage tank 63 to thaw frozen water. The level of water stored in the water tank 63, as identified by the water level sensor 65, may be communicated to the vehicle operator and / or used to adjust engine operation. For example, a water level indicator or an indication on a vehicle instrument panel (not shown) may be used to communicate the water level.If the water level in the water tank 63 is higher than a threshold level, it can be concluded that there is sufficient water available for injection, and accordingly, water injection can be activated by the controller. Otherwise, if the water level in the water tank 63 is lower than the threshold level, it can be concluded that there is insufficient water available for injection, and therefore, water injection can be deactivated by the controller.

[0025] In the depicted embodiment, the water storage tank 63 may be manually refilled via the water fill channel 69 and / or automatically refilled by the collection system 72 via the water tank fill channel 76. The collection system 72 may be coupled to one or more vehicle components 74 so that the water storage tank onboard the vehicle may be refilled with condensate collected from various engine or vehicle systems. In one example, the collection system 72 may be coupled to an EGR system and / or exhaust system to collect condensed water from exhaust gas passing through the system. In another example, the collection system 72 may be coupled to an air conditioning system (not shown) for collected water condensed from air passing through an evaporator. In yet another example, the collection system 72 may be coupled to a vehicle exterior surface to collect rain or atmospheric condensation.The manual fill channel 69 may be fluidly coupled to a filter 68, which may remove some impurities contained in the water. A drain 92 including a drain valve 91 may be used to drain water from the water storage tank 63 to a location outside the vehicle (e.g., to the road), for example, when a water quality is deemed lower than a threshold and not suitable for injection into the engine (e.g., due to high conductivity, high particulate matter content). In one example, the water quality may be assessed based on the output of a conductivity sensor 93 coupled to the water injection system 60 in the water line 61. In other examples, the sensor 93 may be a capacitance sensor, an optical sensor, a turbidity sensor, a density sensor, or another type of water quality sensor. As described with reference to FIG. Fig. As outlined in Figures 2-3, a diagnostic test may be performed intermittently on the water injection system to reliably test the system itself and identify blockages in one of the water injection lines 161. Based on the detection of blockages, future water injection may be discontinued.

[0026] Fig. 1 further shows a control system 28. The control system 28 may be communicatively connected to various components of the engine system 100 to perform the control routines and operations described herein. The control system 28 may include an electronic digital controller 12. The controller 12 may be a microcomputer, including a microprocessor unit, input / output ports, an electronic storage medium for executable programs and calibration values, random access memory, keep alive memory, and a data bus. The controller 12 may receive inputs from a plurality of sensors 30, such as the various sensors of Fig. 1 to receive inputs, including transmission gear position, throttle pedal position, braking demand, vehicle speed, engine speed, mass air flow through the engine, boost pressure, ambient conditions (temperature, pressure, humidity), etc. Other sensors include CAC 118 sensors, such as CAC intake air temperature, ACT sensor 125, exhaust pressure and temperature sensors 80, 82 and pressure sensor 124, CAC outlet air temperature sensor and MCT sensor 23, knock sensor 183 for determining end gas ignition and / or water distribution among cylinders, and others. The controller 12 receives signals from the various sensors. Fig. 1 and exposes the various actuators Fig. 1 to adjust engine operation based on the received signals and instructions stored in a memory of the controller. For example, injecting water into the engine may include adjusting a pulse width of the injectors 45-48 to vary an amount of injected water, while also adjusting a timing of the water injection and a number of injection pulses. In some examples, the storage medium may be programmed with computer-readable data representing instructions executed by the processor to perform the methods described below (e.g., in Fig. 3) as well as other variants that are expected but not specifically listed are executable.

[0027] In this way, the system enables Fig. 1 illustrates a vehicle system comprising an engine; a water injection system including a water reservoir, a water injector, and a water collection system; a transmission coupling the engine to vehicle wheels having a plurality of variable speed ratios; a water quality sensor coupled to the water reservoir; a mass air flow (MAF) sensor; a knock sensor; and a controller. The controller may be configured with computer-readable instructions stored on non-transitory memory to: ramp water injection from a lower limit to an upper limit; when the engine is in a first speed load range during the ramp, determine a first injection error as a percentage of water injection based on an actual change in knock sensor output relative to an expected change in knock sensor output;when the engine is in a second speed load range during the ramp-up, determining a second injection error as a percentage of water injection based on an actual change in spark timing relative to an expected change in spark timing; when the engine is in a third speed load range during the ramp-up, determining a third injection error as a percentage of water injection based on an actual change in MAF relative to an expected change in MAF; estimating an average injection error based on at least two of the first, second, and third errors;and indicating degradation of the water injection system based on the average injection error. The controller may optionally include further instructions to: when a water level in the reservoir is higher than a threshold level, estimating a water quality based on a refill location and / or based on an output of a water quality sensor (e.g., a conductivity sensor, a turbidity sensor, etc.); and predicting an expected injection error for the water injection system based on the estimated water quality. Further, the controller may include further instructions to: when the estimated water quality is lower than a first threshold, increasing the use of water in an engine operating window defined by each of a water contamination level and a type of contaminant present in the water;and if the estimated water quality is lower than a second threshold and lower than the first threshold, draining the water from the reservoir. Indicating deterioration may include indicating clogging of the water line of the water injection system, where a degree of clogging is based on the average injection error relative to the expected injection error. The controller may then inject water from the water injector in response to an indication of knock, a water injection pulse width being adjusted based on the average injection error.

[0028] Now, with reference to Fig. 2 shows an example routine 200 for reliably performing a self-test of the lines of a water injection system coupled to a vehicle. The method allows blockages in the water system to be identified more quickly and accurately, thus allowing them to be contained in a timely manner. Instructions for carrying out the method 200 and the other methods included herein can 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 use motor actuators of the engine system to adjust engine operation according to the methods described below.

[0029] At 202, the method includes determining whether the water level in a water tank or reservoir of an engine water injection system is higher than a threshold level, such as 10% of capacity. If not, the method includes, at 204, requesting a manual refill of the water tank and / or increasing the on-board water collection. The water injection system may be coupled to an engine of a vehicle, and the water in the reservoir may be manually refilled from a water source external to the vehicle, such as a water pipe. Additionally or alternatively, the reservoir may be refilled on-board via a collection system that collects condensate from one or more components, such as an EGR cooler, a charge air cooler, an air conditioning evaporator, an exhaust heat exchanger, and a vehicle exterior surface. As described with reference to the system of Fig. As set forth in Figure 1, the water reservoir may be refilled with condensate, including, but not limited to, water condensed from exhaust gas flowing through an EGR system and water condensed from air flowing through an evaporator of a vehicle air conditioning system. Once the threshold level in the water reservoir is reached, the routine moves to 206.

[0030] At 206, the method includes estimating the water quality in the water tank. Thus, the type of contaminants present in the water, as well as the degree of contamination, can vary greatly based on the source from which the vehicle operator refilled the water tank. As an example, it may be recommended to refill the water tank with distilled water, but the vehicle operator may instead refill with tap water or well water. Thus, different water sources may contain different types and amounts of minerals and other contaminants that could potentially cause deposits on water filters, water injectors, engine components, exhaust catalysts, etc. The catalysts may also become chemically contaminated.In one example, the water quality in the water tank may be estimated based on the output of the water quality sensor coupled to the water reservoir, where the water quality estimate is based on a conductivity value or the ionic strength of the water (as detected by a conductivity sensor, for example). In alternative examples, the water quality may be estimated based on the ionic strength of the water, a particulate matter content, a turbidity sensor, a density sensor, a refractive index, etc.

[0031] In still other examples, water quality may be derived based on the water refill location using knowledge of the vehicle's location (such as GPS data, locations of nearby Wi-Fi hotspots, etc.) combined with knowledge of the local water quality at that location (such as determined internally in the vehicle or retrieved from a database, such as an internet water quality database for municipal water systems and groundwater). If the water quality value was derived or retrieved from a remote location, the controller may further enhance the data with historical contaminants recorded after refilling at the same location (as detailed below).The history may be based on data collected in-vehicle on the given vehicle or collected in-vehicle on another vehicle and retrieved via vehicle-to-vehicle (V2V) or vehicle-to-infrastructure communication. In one example, the water quality may be assigned an index value or rating number. At 208, the estimated water quality (e.g., the index value or rating number, or the conductivity value) is compared to a threshold that depends on the water quality sensor used. For example, a lower reading from a turbidity sensor may be assigned a high water quality index value, and turbidity readings below 5 NTU may correspond to water quality index values ​​above the threshold.The threshold may correspond to a minimum water quality level necessary to enable water injection into the engine without impacting engine performance or combustion characteristics. In some examples, the estimated water quality may be compared to each of a lower threshold, below which water injection may always be disabled, and an upper threshold, above which water injection may always be enabled. Between the upper and lower thresholds, water injection may be limited; for example, an operating window within which water injection is permitted may be limited or varied.

[0032] If the estimated water quality is below the threshold, then at 210 the method includes draining the water from the water reservoir, such as by opening a solenoid-controlled drain valve coupling the water reservoir to a drain pipe that releases the water to a location external to the vehicle. The water may be completely or partially drained, with the selection based on the extent of water contamination and / or predictions for future water refills, water consumption rates, and condensate collection rates. In one example, if draining the water added to the reservoir is selected, the controller may close the vehicle refill tank cap or close a valve coupled upstream of the tank inlet while redirecting the incoming water to a drain.

[0033] Additionally, a controller's memory may be updated with GPS coordinate information of the location when water was refilled at an off-vehicle location to indicate that the water source was contaminated. Further, the controller may limit access to a water tank refill port / cap based on the water contamination indication. As a result, future manual water tank refills from that location may be limited or at least temporarily blocked. In one example, an access door to the water tank refill port may be configured with a locking mechanism that is opened by a user interface in a vehicle cabin space that is in communication with the controller. The controller may provide location-based indications (e.g.,The controller may issue warning signals (e.g., warning sounds or lights, or messages displayed on a vehicle display on a center console) when the local contamination level of the tap or well water exceeds a threshold level based on a predicted contamination risk. The controller may ask the vehicle operator to confirm refilling with the appropriate water (e.g., distilled water) by pressing a button or saying "yes" before allowing the water tank refill door to be opened.

[0034] In still further examples, when the water quality is below the threshold, instead of draining the water, the controller may increase water usage to "use up" the water to accommodate cleaner water from the condensate collection or a cleaner subsequent refill. In this way, the time until a subsequent water tank refill event is reduced (assuming that the water quality is of higher quality at the next refill event at a different location). As an example, water injection may be enabled below a lower threshold temperature or above an upper threshold temperature even when engine speed load conditions / power consumption do not require water injection for improved engine efficiency and performance, due to the different effects of temperature (of each engine component) on deposit formation at different engine components / locations.In one example, the temperature of each engine component or water injection system component (or at least only the critical ones) may be measured and compared, and then a minimum value may be selected from the data set. In another example, the temperature of each relevant engine component may be derived based on one or more engine operating conditions, including ignition timing, exhaust air-fuel ratio, ambient temperature, vehicle speed, smartphone usage, etc. At the same time, water injection is reduced (or eliminated) during a window where deposits are likely to form.

[0035] If the water quality is above the threshold, the method at 212 optionally includes purifying the water before testing the water injection again. Purifying the water may include one or more of filtration (including filtering the water to remove the particulate matter), distillation, reverse osmosis, and ion exchange. In-vehicle distillation may produce a purified water stream using waste heat from the engine and / or exhaust. Reverse osmosis may be one of a set of selected membrane-based processes. Ion exchange may be used with a packed bed that can either alternate between different solutes, such as calcium and magnesium, which are exchanged for sodium, or exchange said ions for ions comprising water (H + and OH - ).

[0036] In some examples, a purity level and a purification type can be selected after refilling with contaminated water. Specifically, sufficient purification can be provided to reduce scaling problems while avoiding excessive purification, which would increase reactive losses (e.g., energy required to evaporate water for distillation or pump water through a filter) and financial burdens (e.g., cost of replacement filters or ion exchange beds), reducing customer satisfaction (due to additional effort and cost of system maintenance). A purity level can be selected as a function of the amount / proportion of water bypassed to the engine through the purification system or as a function of the time the water spends in the purification system.For example, with increased amount of water diverted or increased time spent in the purification system, the level of cleanliness may increase accordingly.

[0037] Next, at 214, the routine includes adjusting the water injection window based on the type and extent of water contamination. Certain types of contamination may be known to cause deposit problems when certain components are within a certain temperature range. Therefore, a component temperature range where water injection is enabled may be set to be below a lower threshold temperature and above an upper threshold temperature when this type of contamination is detected. As another example, water injection may be performed in a wider range of operating conditions outside of an optimal operating range selected for higher water quality when the water quality exceeds the threshold by a small amount.As another example, water injection may be performed in an even narrower range of operating conditions outside an optimal operating range selected for higher water quality if the water quality deviates from the threshold by a larger amount.

[0038] At 216, the method includes predicting an expected degree of clogging of a water line of the water injection system based on the estimated level and type of contamination. For example, the expected degree of clogging of the water line may increase accordingly as the degree of contamination increases. The expected degree of clogging of the water line may be further determined based on an expected temperature of one or more engine components at a time of water injection.

[0039] At 218, the method includes predicting an expected water injection error for the predicted clogging severity of the water injection system. As the clogging severity increases, an error amount in the water injection amount may increase accordingly. Additionally, a location of the water injection error in the water injection system (e.g., at which component) may be determined.

[0040] At 220, the method includes performing a self-test of the water injection system to determine an actual water injection fault, if possible. The actual extent of the water line blockage may be correlated to the actual water injection fault using a function. As described with reference to Fig. As set forth in Figure 3, estimating the actual water injection error may include increasing water injection during each of a plurality of different engine operating conditions and determining a water injection error based on a change in a set of engine operating parameters at each of the different conditions. Furthermore, the set of engine operating parameters may be different (e.g., non-overlapping or only partially overlapping) for each of the different conditions.For example, during a first condition, water injection may increase, and a first water injection error may be determined based on a change in a first set of engine operating parameters; during a second condition, water injection may increase, and a second water injection error may be determined based on a change in a second set of engine operating parameters; during a third condition, water injection may increase, and a third water injection error may be determined based on a change in a third set of engine operating parameters, and so on. The actual water injection error may then be determined as a function of each of the first, second, and third water injection errors estimated during the self-test.For example, the actual water injection error may be determined as a function of the average of the first, second, and third water injection errors. In another example, the first, second, and third water injection errors may be compared, and only the two closest to each other may be averaged to estimate the actual water injection error. Determining the water injection error may include determining a water shortage percentage, as described with reference to [Figure 1]. Fig. 3.

[0041] Thus, if the self-test is not possible, such as due to unmet self-test conditions, the controller may proceed with adjusting a water injection amount based on the predicted water clogging severity and the associated expected water injection error. For example, the expected water injection error may include an expected water deficiency percentage, and the water injection amount may be adjusted to compensate for the deficiency. In one example, if the expected water deficiency percentage based on the predicted water clogging severity is 30%, the water injection amount (determined based on engine operating conditions) may then be increased by 30% at the time of delivery.

[0042] If the self-test is possible and successful, then at 222 the method includes estimating the actual clogging extent of the water injection system based on the actual water injection error determined during the self-test. For example, the actual clogging extent may be determined as a function of the absolute extent of the actual water injection error or as a function of the actual water injection error relative to the expected water injection error.

[0043] At 224, the method includes performing a corrective action based on the actual clogging level. For example, subsequent water injection to the engine may be adjusted based on both the actual error and the expected error. Water injection may be adjusted by adjusting a commanded water injection amount with a correction factor based on the clogging level. For example, an injection pulse width of a water injector may be adjusted during injection of water from the water reservoir into the engine in response to knock. In one example, if the water starvation percentage is determined to be as high as 30%, a subsequent water injection event requiring 50% water flow (e.g., to address knock) may include the commanded water injection 50% + 30% = 80% water flow.In another example, it may be possible to clear parts of the system by using a higher pressure or flow rate than necessary, or by pulsing the pressure or flow rate, or by reversing the flow in parts of the system.

[0044] In addition, a diagnostic code, such as the self-test code, may be set based on the determined degree of clogging, and the vehicle operator may be notified of the clogging, such as by illuminating a lamp or message on the vehicle instrument panel.

[0045] At 226, the method includes determining whether water injection is requested. If water injection is not requested, engine operation may continue without water injection at 228. Otherwise, if water injection is requested, engine operation may continue at 230 with water injection into a water injection window selected based on engine speed load conditions and engine knock limitations. For example, water injection may continue at a high engine speed load condition with the water injection amount adjusted with the clogging severity-based correction factor.

[0046] Additionally, a water injection amount can be adjusted based on at least one of the actual and predicted water injection errors. Specifically, a water injection amount can be commanded with a correction factor based on either the actual or predicted clogging extent. Furthermore, the water injection amount can be commanded with a correction factor based on both the actual and predicted clogging extent (e.g., based on a comparison of the actual clogging extent with the predicted clogging extent). For example, if the self-test is not completed, the water injection amount can be commanded based on the predicted clogging extent and the associated expected water injection error.Otherwise, once the self-test is complete, the water injection amount may be adjusted based on the predicted clogging level and the associated expected water injection error. The controller may feedforward estimate a clogging level based on the water quality in the water injection system (or the predicted injection error); feedforward adjust the feedforward estimated clogging level based on the actual injection error; and then inject water into the engine as a function of a commanded water injection amount and the feedforward adjusted clogging level. The commanded water injection amount may be a base value retrieved from a lookup table in the controller's memory as a function of at least engine speed and load.In this way, a degree of clogging of the water injection system is determined based on a best available estimate of an injection error and the water injection is compensated accordingly.

[0047] In this way, water pipe blockages can be reliably diagnosed and repaired promptly.

[0048] Now, with reference to Fig. 3 an example method 300 for self-testing the water injection system from Fig. 1. The method enables the reliable determination of an actual water injection error as a function of water injection errors determined based on different engine operating parameters at different engine operating conditions. The method from Fig. 3 can be used as part of the routine Fig. 2, such as 220.

[0049] At 302, the method includes confirming that the engine is in a first speed load range, for example, a speed load range where the engine is limited by knock. In one example, the first speed load range includes the engine being in a high load range while the engine speed is below a threshold speed. If the first engine speed load range is confirmed, the method includes, at 310, increasing water injection into the engine. The water injection may increase from zero flow to full flow or to maximum flow, which is feasible when the engine is operating in the first engine speed load range. Alternatively, the water injection may increase from zero flow to a threshold flow required to enable the self-test to be reliably completed without wasting water.As used herein, injecting the water and increasing the water injection includes one or more of directly injecting the water into an engine cylinder using direct water injection, injecting the water into an intake port upstream of an intake valve using a port water injection device, and injecting the water into an intake manifold upstream or downstream of an intake throttle using a central water injection device.

[0050] At 312, the method includes measuring a change in a first set of engine operating parameters during the ramp-up. The first set of parameters may include an engine knock level as a percentage of water injection and an engine spark retard as a percentage of water injection. For example, knock and spark changes are measured as water injection ramps up and compared to expected knock and spark changes related to the percentage of water injected. Then, the controller may determine a water starvation percentage based on the knock and spark changes. For example, it may be expected that under current conditions, MBT spark timing with no knock can be achieved when the water injection amount is at least 20%.However, if knock continues to limit spark timing until 50% water injection is commanded, the controller may infer that there is a 30% loss in water flow. In another example, the initial engine operating parameters may include a change in mass air flow (MAF) into the engine as a percentage of water injection, since higher water injection results in cooler, denser air and therefore a higher MAF.

[0051] At 314, the method includes determining a first injection error for the first engine speed load range based on the estimated change in the first set of parameters during the ramp-up, including as a function of the percentage of water injection.

[0052] Returning to 302, if the first speed load range is not confirmed, the method moves to 304 to confirm whether the engine is in a second speed load range, for example, a part-load speed load range. In one example, the second speed load range includes the engine operating at part-load conditions. This method is used because different engine parameters may be suitable for quantifying system clogging in different engine speed load ranges. If the second engine speed load range is confirmed, the method includes increasing water injection into the engine at 320. The water injection may increase from zero flow to full flow or to maximum flow, which is feasible when the engine is operating in the second engine speed load range.Alternatively, water injection may increase from zero flow to a threshold flow required to enable the self-test to be reliably completed without limiting combustion stability. As used herein, injecting water and increasing water injection includes one or more of direct, port, and center injection of water into an engine cylinder.

[0053] At 322, the method includes measuring a change in a first set of engine operating parameters during the ramp-up. The second set of parameters may include engine spark timing (e.g., change in a degree of applied spark retard) as a percentage of water injection and mass air flow (MAF) as a percentage of water injection. The second set of parameters may further include a change in engine torque output compared to spark timing because the water acts as a diluent, increasing MBT spark timing. In other words, MBT spark will correspond to a higher spark value, and torque will drop below MBT. The controller may detect MBT of 100% water compared to 0% water at the spark value where torque begins to drop.In one example, torque and spark changes are measured as water injection increases and compared to expected torque and spark changes related to the percentage of water injected. Then, the controller may determine a water starvation percentage based on the torque and spark changes. Torque changes may be inferred based on a change in vehicle acceleration or based on input from a torque sensor. For example, the controller may calculate the water starvation percentage based on a difference in the actual spark change relative to the expected spark change for the given water injection percentage as water increases. As another example, MAF may change during the increase in water injection because volumetric efficiency improves with water injection.The controller can compare the actual MAF (or actual change in MAF) with the expected MAF (or expected change in MAF) for the given throttle position (e.g., the degree of throttle opening at the part-throttle position), cam timing, and / or air charge temperature (ACT). The water starvation percentage can then be calculated based on the difference in the actual MAF change relative to the expected MAF change for the given water injection percentage as the water increases during the part-throttle condition.

[0054] In yet another example, the second of the engine operating parameters may include a change in manifold absolute pressure (MAP) into the engine as a percentage of water injection. The change in MAP may also be based on the improvement in volumetric efficiency with water injection. The controller may compare actual change in MAP with expected change in MAP for the given throttle position (e.g., the degree of throttle opening at the part-throttle position), cam timing, and / or air charge temperature (ACT). The water starvation percentage may then be calculated based on a difference between the actual MAP change relative to the expected MAP change for the given water injection percentage as water increases during the part-throttle condition.

[0055] At 324, the method includes determining a second injection error for the second engine speed load range based on the estimated change in the second set of parameters during the ramp-up, including as a function of the percentage of water injection.

[0056] Returning to 304, if the second speed load range is not confirmed, the method moves to 306 to confirm whether the engine is in a third speed load range, for example, a high speed load range (where the engine speed is above a threshold speed and the engine load is above a threshold load). In one example, the third speed load range includes the engine operating at high power consumption with water injection enabled for catalyst cooling. The third speed load range may be selected for water-injected engine operation when maximum power is requested. As another example, the third speed load range may be selected for water-injected engine operation in response to an exhaust catalyst temperature or an exhaust flange temperature above or at a threshold temperature.The exhaust catalyst temperature or exhaust flange temperature can be a measured or modeled temperature.

[0057] If the third engine speed load range is confirmed, the method includes increasing water injection into the engine at 330. The water injection may increase from zero flow to full flow or to maximum flow, which is feasible when the engine is operating in the third engine speed load range. Alternatively, the water injection may increase from zero flow to a threshold flow required to enable the self-test to be reliably completed without impacting torque output. As used herein, injecting the water and increasing the water injection includes one or more of direct, port, and center injection of water into an engine cylinder.

[0058] At 332, the method includes measuring a change in a first set of engine operating parameters during the ramp-up. The third set of parameters may include a change in torque output, a change in exhaust catalyst temperature, and a change in manifold airflow as a percentage of water injection. For example, torque and MAF changes are measured as water injection ramps up and compared to expected torque and MAF changes related to the percentage of water injected. Then, the controller may determine a water starvation percentage based on the torque and MAF changes. Torque changes may be inferred based on a change in vehicle acceleration or based on input from a torque sensor.In yet another example, where the vehicle system is a hybrid vehicle system including a power-split high-voltage hybrid engine, the controller may measure torque based on how the engine receives or responds to engine torque. For example, engine torque may be determined based on the engine torque commanded to maintain engine speed. The water starvation percentage may be calculated based on a difference between the actual MAF change and the expected MAF change for the given percentage of water injection as water increases. In yet another example, the third set of engine operating parameters may include a change in manifold absolute pressure (MAP) into the engine as a percentage of water injection.

[0059] At 334, the method includes determining a third injection error for the third engine speed load range based on the estimated change in the third set of parameters during the ramp-up, including as a function of the percentage of water injection.

[0060] From each of 314, 324, 334, the method moves to 340, where the method includes determining an average injection error based on at least two of the first, second, and third injection errors. The at least two of the first, second, and third errors may be selected to have a sub-threshold deviation in relative error values. In other words, the controller may select two of the three that are closest to each other (e.g., within 10% of each other). Then, an average of these two may be determined as the actual injection error.

[0061] At 342, the method includes retrieving an expected injection error based on the water contamination level. For example, as described with reference to Fig. 2, a water injection failure can be predicted based on the amount and type of contaminants in the water in the water tank.

[0062] At 344, the method includes comparing the actual water injection error (determined at 336) with the predicted water injection error (retrieved at 338) to determine a clogging level of the water line. For example, the clogging level may be determined as a function of the difference between the actual injection error relative to the expected water injection error. In one example, the controller may feedforward estimate a clogging level based on the expected water injector error and then feedforward adjust the feedforward estimated clogging level based on the actual injection error.

[0063] As in Fig. 2, the controller may then adjust water injection to the engine based on the determined clogging level. In particular, the amount of water injection delivered to the engine may be determined as a function of a commanded water injection amount and the feedback-adjusted clogging level. For example, an injection pulse width of a water injector may be adjusted during the injection of water from the water reservoir to the engine in response to knock. In one example, if the water starvation percentage is determined to be as high as 30%, a subsequent water injection event requiring 50% water flow (e.g., to address knock) may include the commanded water injection 50% + 30% = 80% water flow.For example, the controller may determine a control signal to send to the water injector actuator, such as determining a pulse width of the signal based on a determination of the clogging severity. The controller may determine the pulse width by a determination that directly takes into account a particular clogging severity or water starvation percentage, such as increasing the pulse width as the clogging severity or water starvation percentage increases. Alternatively, the controller may determine the pulse width based on a calculation using a lookup table, where the input is clogging severity (or water starvation percentage, or difference between actual water injection error and actual error), and the output is pulse width. As another example, the controller may make a logical determination (e.g.,The controller may then make a control action (regarding a position of a water injector actuator) based on logic rules that are a function of the degree of clogging. The controller may then generate a control signal that is sent to the water injector actuator.

[0064] If none of the first, second, or third speed load ranges are confirmed, then at 308 the method may include actively shifting the engine into the target speed load range by adjusting one of a transmission, a hybrid axle system, and an accessory coupled to the engine to maintain the engine in a speed load range that meets the first, second, or third condition. For example, the engine may be actively shifted into the target speed load range via powertrain adjustments to a stepped transmission (gear shift) or a belt gear ratio of a continuously variable transmission (CVT), or a hybrid axle system, or an engine accessory such as an alternator. In one example, the controller may shift gears or change belt ratios of a CVT to shift the engine into the target speed load range.In another example, the controller may actively and sequentially place the engine into the first, second, and third speed load ranges when the self-test conditions are met but the target speed load range is not met. In an example where the vehicle is a hybrid electric vehicle, high load conditions may be actively enforced, rather than waiting for high load conditions, by lowering the engine speed by selecting a gear ratio of a power-split powertrain having an electronic CVT that provides the required engine speed. Alternatively, if the powertrain includes a hybrid axle drive, an operating condition may be selected that increases the engine power, torque, or load by offsetting battery power. Thus, wheel torque on the vehicle may remain unchanged when using the settings.In this way, the required speed load range can be provided without causing torque deviations.

[0065] In this way, a controller may estimate an actual clogging extent of the water injection system based on the average injection error, compare the actual extent with a predicted clogging extent of the water line, the predicted extent being based on an estimated quality of water replenished in the water reservoir, and, based on the comparison, adjust an amount of water injected into the engine in response to a subsequent indication of knock.

[0066] It is understood that an expected water injection failure, associated with the predicted probability of clogging, can be determined and used as an initial estimate until the actual extent of clogging or injection failure can be determined. If conditions permit a self-test of the water injection system, an actual injection failure can then be determined based on a change in a set of engine operating parameters during a water injection ramp-up.

[0067] Fig. 4 shows a Fig. , which illustrates an example self-test of a water injection system and adjustments to a knock-relieving water injection in response to the indication of a water line blockage during the self-test. Fig.represents the engine speed at trace 402, the measured MAF at trace 404 (solid line), the expected MAF at trace 405 (dashed line), the engine torque output at trace 406, the engine water injection at trace 408, and the engine water starvation at trace 410. All traces are plotted over time along the X-axis.

[0068] Before t1, the engine may be operated at lower engine speeds without water injection. At t1, the water injection system self-test conditions may be met and a self-test may be initiated. At t2, the self-test may be completed and the water injection ramp may be terminated. Between t1 and t2, water injection increases to a maximum amount possible for the given operating conditions. Based on the difference between the measured MAF and the expected MAF during the period t1-t2, a water starvation percentage is determined. In the illustrated example, a water starvation percentage of 411 is determined and stored in the controller's memory. In one example, a water starvation of 30% may be determined based on the measured MAF relative to the expected MAF during the water ramp.

[0069] Between t2 and t3, the engine operates in speed load ranges where water injection is not required. At t3, water injection is commanded in response to an increase in driver torque demand and a corresponding increase in engine output torque. Between t3 and t4, water is injected into the engine taking into account the amount of water required for knock, dilution, and / or catalyst temperature control at the given operating conditions, and further based on the determined water starvation percentage. Specifically, water injection is provided at stage 408, which is greater than stage 409, which would have been applied if the water starvation were at 0%.

[0070] It should be understood that while the illustrated example adjusts water injection based on a measured clogging level and a calculated water starvation percentage calculated based on the measured MAF error during the self-test, water injection may be adjusted based on an expected clogging level and an expected water starvation percentage if the self-test conditions are not met or the self-test results are not available. For example, an engine controller may use the water quality estimate to predict the clogging level (e.g., clogging time over time) as a feedforward estimate and then use a determination of actual clogging (feedbacked based on the self-test, if available) to update the clogging level and water starvation percentage over time.The clogging estimate (including the feedback value plus the feedforward value) can then be used to adjust water injection when water injection is commanded so that a more accurate amount of water injection can be provided.

[0071] In this way, the water injection system can reliably diagnose itself by diagnosing different sets of engine parameters at different engine speed and load ranges while water is injected into the engine. As a result, sensor data can be reliably measured, and the test results can have a higher confidence level. The technical effect of predicting water injection failures based on the estimated quality of water being added to the water tank is that water injection system clogging can be better identified based on the deviation of an actual failure from the predicted failure. By reducing engine damage caused by contaminated water and by accurately controlling water injection, even with partial clogging, engine operating costs are reduced. In addition, engine warranty issues are reduced.Overall, the use of water injection in an engine can be expanded, providing benefits in terms of fuel efficiency and engine performance.

[0072] An example method for an engine includes: predicting an expected injection error for a water injection system that delivers water to the engine based on water quality in a water reservoir; estimating an actual injection error based on a change in engine parameters during the ramp-up of water injection; and adjusting water injection to the engine based on either the expected error or the actual injection error. In the preceding example, adjusting additionally or optionally includes indicating a clogging level of the water injection system based on a best available estimate of an injection error and adjusting a commanded water injection amount with a correction factor based on the clogging level. In any of the preceding examples, adjusting additionally or optionally includes feedforward estimating a clogging levelbased on water quality; feedback-adjusting the feedforward estimated clogging level based on the actual injection error; and injecting water into the engine as a function of a commanded water injection amount and the feedback-adjusted clogging level. In each of the preceding examples, estimating an actual injection error additionally or optionally includes: during a first state, increasing water injection and determining a first water injection error based on the change in a first set of engine parameters; during a second state, increasing water injection and determining a second water injection error based on the change in a second set of parameters; during a third state, increasing water injection and determining a third water injection error based on the change in a third set of parameters;and estimating the actual injection error as an average of at least two of the first, second, and third errors. In each of the preceding examples, at least two of the first, second, and third errors additionally or optionally have a lower threshold deviation than in relative error values. In each of the preceding examples, the method additionally or optionally comprises adjusting one of a transmission and a hybrid system and an accessory coupled to the engine to maintain the engine in a speed load range corresponding to the first, second, or third condition. In each of the preceding examples, the first condition additionally or optionally includes an engine load higher than a threshold load and an engine speed lower than a threshold speed, and the first set of parameters includes a change in knock frequency, a change in spark timing, and aChange in mass air flow; the second condition includes an intake throttle opening that is lower than a threshold opening, and the second set of parameters includes a change in torque output, a change in ignition timing, a change in mass air flow, and a change in manifold absolute pressure; and the third condition includes an engine load that is higher than a threshold load and includes an engine speed that is higher than a threshold speed, and the third set of parameters includes a change in torque output, a change in exhaust catalyst temperature, and a change in mass air flow. In one of the preceding examples, the engine is additionally or optionally coupled to a vehicle, and wherein the water in the reservoir is manually refilled from a water source external to the vehicle or is refilled internally via a collection system, wherein the collection system collects condensate from one or moreseveral of an EGR cooler, a charge air cooler, an air conditioning evaporator, an exhaust gas heat exchanger, and a vehicle exterior surface. In any of the preceding examples, the method additionally or optionally further comprises: estimating the water quality in the water reservoir based on a refill location and / or based on a water quality sensor; if the estimated quality is higher than a threshold, purifying the water before injecting the water; and if the estimated quality is lower than a threshold, draining the water from the water reservoir or increasing the use of the water in an engine operating window determined based on the estimated quality. In any of the preceding examples, the method further comprises additionally or optionally, in response to the estimated water quality being lower than the threshold, wherein the water is collected from an off-vehicle water sourcehas been refilled, indicating that the water source is contaminated and preventing future refills at the water source.

[0073] Another example method for an engine includes: injecting water from a water reservoir into an engine in response to knock; during a first condition, increasing water injection and determining a first water injection error based on a change in a first set of parameters during the increase; during a second condition, increasing water injection and determining a second water injection error based on a change in a second set of parameters during the increase; during a third condition, increasing water injection and determining a third water injection error based on a change in a third set of parameters during the increase; determining an average injection error based on at least two of the first, second, and third errors; and indicating clogging of the water injection system based on the average injection error.In the preceding example, the method additionally or optionally comprises, in response to the indication, adjusting an injection pulse width of a water injector during injecting water from the water reservoir into the engine in response to knock. In any of the preceding examples, the method additionally or optionally further comprises: estimating an actual degree of clogging of the water line based on the average injection error; comparing the actual degree to a predicted degree of clogging of the water line, wherein the predicted degree is based on an estimated quality of water refilled into the water reservoir; and based on one or more of the actual degree and predicted degree of clogging, adjusting an amount of water injected into the engine in response to a subsequent indication of knock.In each of the preceding examples, the first state, additionally or optionally, includes the engine being knock limited, and the first set of parameters includes engine knock level as a percentage of water injection and engine spark retard as a percentage of water injection, the second state includes the engine operating at part load, and the second set of parameters includes engine spark retard as a percentage of water injection and mass air flow as a percentage of water injection, and the third state includes the engine operating at high speed and high load, and the third set of parameters includes the change in torque output as a percentage of water injection and mass air flow as a percentage of water injection.In any of the preceding examples, the method additionally or optionally further comprises adjusting a speed ratio of the transmission or adjusting a hybrid system or adjusting accessories coupled to the engine to maintain the engine in a first speed load range during the first condition, in a second speed load range during the second condition, and in a third speed load range during the third condition, wherein the first, second, and third speed load ranges do not overlap or partially overlap.In each of the preceding examples, injecting the water includes, additionally or optionally, one or more of injecting the water directly into an engine cylinder using a direct water injection device, injecting the water into an intake port upstream of an intake valve using a port water injection device, and injecting the water into an intake manifold upstream or downstream of an intake throttle using a central water injection device.

[0074] Another example vehicle system includes: an engine; a water injection system including a water reservoir, a water injector, and a water collection system; a transmission coupling the engine to the vehicle wheels; a water quality sensor coupled to the water reservoir; a mass air flow (MAF) sensor; a knock sensor; and a controller with computer-readable instructions stored in non-transitory memory to: ramp up water injection from a lower limit to an upper limit; when the engine is in a first speed load range during the ramp up, determine a first injection error as a percentage of water injection based on an actual change in knock sensor output relative to an expected change in knock sensor output;when the engine is in a second speed load range during the ramp-up, determining a second injection error as a percentage of water injection based on an actual change in spark timing relative to an expected change in spark timing; when the engine is in a third speed load range during the ramp-up, determining a third injection error as a percentage of water injection based on an actual change in MAF relative to an expected change in MAF; estimating an average injection error based on at least two of the first, second, and third errors;and indicating degradation of the water injection system based on the average injection error. In the preceding example, the controller additionally or optionally includes further instructions to: when a water level in the reservoir is higher than a threshold level, estimating a water quality based on the refill location and / or based on an output of the water quality sensor; and predicting an expected injection error for the water injection system based on the estimated water quality. In any of the preceding examples, the controller additionally or optionally includes further instructions to: when the estimated water quality is lower than a first threshold, increasing use of the water in an engine operating window defined by each of a water contamination level and a type of contaminant present in the water;and if the estimated water quality is lower than a second threshold and lower than the first threshold, draining the water from the reservoir. In any of the preceding examples, indicating the impairment includes, additionally or optionally, indicating clogging of the water injection system, wherein a degree of clogging is based on the average injection error relative to the expected injection error, and wherein the controller includes further instructions to: inject water from the water injector in response to an indication of knock, a water injection pulse width adjusted based on the average injection error;

Claims

[1] A method for an engine, comprising: Predicting an expected injection error for a water injection system that delivers water to the engine based on water quality in a water storage tank; Estimating an actual injection error based on a change in engine parameters during the rise of water injection; and Adjusting water injection into the engine based on either the expected injection error or the actual injection error. [2] The method of claim 1, wherein adjusting includes indicating a clogging level of the water injection system based on a best available estimate of an injection error and adjusting a commanded water injection amount with a correction factor based on the clogging level. [3] The method of claim 1, wherein the setting includes: feed-forward estimation of clogging level based on water quality; feedback adjustment of the feedforward estimated clogging level based on the actual injection error; and Injecting water into the engine as a function of a commanded water injection quantity and the feedback-controlled clogging level. [4] The method of claim 1, wherein estimating an actual injection error includes: during a first condition, increasing water injection and determining a first water injection fault based on the change in a first set of engine parameters; during a second condition, increasing water injection and determining a second water injection fault based on the change in a second set of engine parameters; during a third condition, increasing water injection and determining a third water injection fault based on the change in a third set of engine parameters; and Estimate the actual injection error as an average of at least two of the first, second and third errors. [5] The method of claim 4, wherein the at least two of the first, second and third errors have a deviation of the relative error values ​​that is smaller than the threshold value. [6] The method of claim 4, further comprising adjusting one of a transmission and a hybrid system and an accessory coupled to the engine to maintain the engine in a speed load range corresponding to the first, second, or third condition. [7] The method of claim 4, wherein the first condition includes an engine load higher than a threshold load and an engine speed lower than a threshold speed, and the first set of engine parameters includes a change in knock frequency, a change in spark timing, and a change in mass air flow; wherein the second condition includes an intake throttle opening lower than a threshold opening, and the second set of engine parameters includes a change in torque output, a change in spark timing, a change in mass air flow, and a change in manifold absolute pressure;and wherein the third condition includes an engine load higher than a threshold load and an engine speed higher than a threshold speed, and the third set of parameters includes a change in torque output, a change in exhaust catalyst temperature, and a change in mass air flow.; [8] The method of claim 1, wherein the engine is coupled to a vehicle and wherein the water in the water storage tank is manually refilled from a water source external to the vehicle or is refilled internally by means of a collection system, the collection system collecting condensate from one or more of an EGR cooler, a charge air cooler, an air conditioning evaporator, an exhaust gas heat exchanger, and a vehicle exterior surface. [9] The method of claim 8, further comprising: Estimating the water quality in the water storage tank based on the refill location and / or based on a water quality sensor; if the estimated quality is higher than a threshold, cleaning the water before the water is injected; and if the estimated quality is less than the threshold, draining the water from the water storage tank or increasing the use of the water within an engine operating window determined based on the estimated quality. [10] The method of claim 9, further comprising, in response to the estimated water quality being lower than the threshold, wherein the water was refilled from an off-vehicle water source, indicating that the water source is contaminated and disabling future refilling of the water storage tank at the water source. [11] Vehicle system comprising: an engine; a water injection system including a water storage tank, a water injection device, and a water collection system; a transmission that couples the engine to vehicle wheels having a variety of speed ratios; a water quality sensor coupled to the water storage tank; a mass air flow (MAF) sensor; a knock sensor; and a controller with computer-readable instructions stored in non-volatile memory to: the increase of water injection from a lower limit to an upper limit; when the engine is in a first speed load range during the ramp-up, determining a first injection error as a percentage of water injection based on an actual change in knock sensor output relative to an expected change in knock sensor output; when the engine is in a second speed load range during the ramp-up, determining a second injection error as a percentage of water injection based on an actual change in spark timing relative to an expected change in spark timing; when the engine is in a third speed load range during the ramp-up, determining a third injection error as a percentage of water injection based on an actual change in MAF relative to an expected change in MAF; estimating an average injection error based on at least two of the first, second and third errors; and indicating the deterioration of the water injection system based on the average injection error. [12] The system of claim 11, wherein the controller includes further instructions to: if a water level in the water storage tank is higher than a threshold level, estimating a water quality based on the refill location and / or on an output of the water quality sensor; and Predicting an expected injection error for the water injection system based on the estimated water quality. [13] The system of claim 12, wherein the controller includes further instructions to: if the estimated water quality is lower than a first threshold, increasing the use of the water in an engine operating window defined by each of a water contamination level and a type of contaminant present in the water, and if the estimated water quality is lower than a second threshold which is lower than the first threshold, draining the water from the water storage tank. [14] The system of claim 12, wherein indicating the impairment includes indicating clogging of the water injection system, wherein a degree of clogging is based on the average injection error relative to the expected injection error, and wherein the controller includes further instructions to: Injecting water from the water injector in response to a knock signal, a water injection pulse width set based on the average injection error.

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