WATER INJECTION FREEZE PROTECTION SYSTEM

Abstract

Water injection system, including: a first container (202, 452) containing a fluid with water, wherein the first container (202, 452) is only directly fluidically coupled to a second container (208, 454), wherein the second container (208, 454) is positioned on a vertically lower plane than the first container (202, 452), and wherein the second container (208, 454) is fluidically coupled to a fluid injection device of an engine (10, 408); a first coolant line (218, 464) in heat exchange relationship with the second container (208, 454); and a first coolant valve (216, 417) along the first coolant line (218, 464) designed to control a flow of coolant through the first coolant line (218, 464), wherein the first coolant valve (216, 417) is open in response to the fact that a temperature of the first container (202, 452) is below a first threshold and a temperature of a coolant at a heat recovery source is above a second threshold, and wherein the first coolant valve (216, 417) is closed in response to the temperature of the first reservoir (202, 452) exceeding the first threshold, thereby stopping the flow of coolant through the first coolant line (218, 464); wherein the first coolant line (218, 464) is fluidically connected to a coolant system of a power electronics of a hybrid electric vehicle.

Description

Area

[0001] The present description generally relates to methods and systems for heating a water injection system reservoir of a vehicle engine. General state of the art / brief description

[0002] Injecting water into a fuel-air mixture in an internal combustion engine reduces the operating temperature in a combustion chamber of the internal combustion engine. Furthermore, injecting water into the fuel-air mixture reduces the production of undesirable byproducts of fuel combustion, such as NOx, carbon monoxide (CO), and various hydrocarbons, thereby improving emissions. A water reservoir may be coupled to the internal combustion engine for injecting water into the combustion chamber. The water from the water reservoir may quickly evaporate due to high temperatures if the water reservoir is located in close proximity to the engine. Thus, the water reservoir may be positioned in an area of ​​a vehicle where the temperature is closer to ambient temperature (for example, near a rear trunk, along a side body, or near a vehicle's fuel tank).However, the water in the water tank may freeze if the ambient temperature drops below freezing, interrupting the water supply to a water injection system.

[0003] Other attempts to solve the problem of water freezing in the water tank of the water injection system include storing and injecting a mixture of water and ethanol from the water tank to prevent the water in the water tank from freezing. Another approach involves electrically heating the water in the water tank using one or more heating elements coupled to the water tank.

[0004] A cold-start heater is known from DE 10 2005 046 029. The cold-start heater comprises a fuel tank coupled to a tank module, wherein a heating element of the cold-start heater is designed as a heating tube that can be integrated into a cooling water circuit, and a control unit designed to regulate a coolant flow through the heating tube. The cold-start heater is further designed to heat a fluid during a cold-start period. Similar systems are known, among others, from EP 2 065 578 A1, DE 10 2012 020 040 A1, EP 3 128 143 A1, and DE 10 2007 061 808 A1.

[0005] However, the inventors have recognized potential problems with such systems. For example, mixing water and ethanol increases costs and complicates the water injection system, which involves complicated air-fuel ratio controls. Additionally, electrically heating the water reservoir increases fuel consumption.

[0006] In one example, the problems described above may be solved by a water injection system including: a first reservoir fluidly coupled to a second reservoir, the second reservoir positioned at a vertically lower level than the first reservoir, the second reservoir fluidly coupled to a water injector of an engine, a first coolant conduit in heat exchange relationship with the second reservoir, and a first coolant valve along the first coolant conduit, upstream of the second reservoir, configured to regulate the flow of coolant through the first coolant conduit.

[0007] In one example, the heat exchange relationship between the coolant line and the water in the second reservoir may occur by transferring / conducting heat from the coolant through walls of the coolant line to the water in the second reservoir. The second reservoir may transfer heat to the first reservoir through walls that share surfaces with both reservoirs. In one example, heat may be transferred to the first reservoir by coolant flowing through a second coolant line in heat exchange relationship with the first reservoir. The heat transfer to the first reservoir may melt ice that has formed in the first reservoir due to a low ambient temperature. The water of the melted ice may drip down from the first reservoir into the fluidly connected second reservoir. Water from the second reservoir may be directed through the water injection line for injection into a combustion chamber of the engine.In another example, the coolant that heats the water in the second reservoir may absorb waste heat from the power electronics system of a hybrid electric vehicle (HEV). A position of the coolant valve may be controlled based on a temperature of the second reservoir and a coolant temperature at the engine or the HEV power electronics system.

[0008] In this way, the water injection system described above ensures the supply of water for injection into the engine's combustion chamber, even when the ambient temperature is below the freezing point of water. In one example, the water injection system is heated by an engine system coolant, and in another example, the water reservoir is heated by an HEV power electronics coolant. This allows the water injection system to be heated in an energy-efficient manner in cold ambient conditions, ensuring the supply of water for injection into the engine's combustion chamber.

[0009] 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 significant 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 address any disadvantages noted above or in any part of this disclosure. Short description of the drawings Fig. 1 shows a schematic representation of an engine system of a vehicle. Fig. 2 shows a first embodiment of a water tank of a water injection system. Fig. 3 shows a second embodiment of a water tank of a water injection system. Fig. 4. illustrates a vehicle coolant system providing heat to a vehicle water injection system reservoir. Fig. 5 shows a flow diagram of an exemplary method for transferring heat from a coolant to a water injection system reservoir. Detailed description

[0010] The following description relates to systems and methods for heating water in a reservoir of a water injection system configured to inject water into a combustion chamber of an engine. A vehicle engine as described in Fig. 1, may be coupled to two or more reservoirs that may contain a primary fuel and / or a secondary fluid (e.g., water) for injection into the cylinders of the engine. Water may be injected into a combustion chamber of the engine to lower the combustion temperature and reduce undesirable combustion byproducts, such as NOx, CO, etc., in vehicle emissions. However, when the ambient temperature drops, the water stored in the reservoir may freeze, which may interrupt the water supply from the reservoir to an injector coupled to a combustion chamber of the engine. Thus, according to the embodiments disclosed herein, a water injection system may include a water reservoir that maintains the water supply from the water reservoir to the engine in the liquid phase even at a low ambient temperature.To achieve this, the water injection system may direct coolant from the engine or from a power electronics system (e.g., if the vehicle in which the engine is installed is a hybrid electric vehicle) to the water injection system reservoir to heat the water and maintain the water supply for injection into the engine's combustion chamber. The . Fig. 2 and Fig. 3 illustrate embodiments of water tanks of water injection systems with coolant flowing in heat exchange relationship with the water tanks. A coolant flow circuit for heating the water in a water injection system tank is shown in Fig. 4. A method for controlling the coolant flow to the water injection system reservoir by controlling a position of a coolant valve based on a temperature of the coolant and a temperature of the water in the water reservoir is illustrated in a flowchart in Fig. 5 illustrates.

[0011] Under conditions when the ambient temperature is low (at or below the freezing temperature of water, 32°F), water in a water injection system reservoir may freeze, and the formation of ice in the reservoir may disrupt the water supply to an injector coupled to the engine. Waste heat absorbed by a coolant from the engine (e.g., from the engine itself or from the engine exhaust) may be used to regulate the temperature of the water injection system reservoir to maintain a supply of water for injection into the engine. In one example, the coolant that transfers heat to the water injection system reservoir may absorb waste heat from an HEV power electronics system.

[0012] An embodiment of a water reservoir system may include two fluidly coupled reservoirs. The relative positioning of the two reservoirs may be such that a first reservoir is vertically higher than a second reservoir. The fluidic coupling of the first reservoir and the second reservoir may be configured to direct a liquid in the first reservoir to flow due to gravity through a conduit into the vertically lower second reservoir. Water from the second reservoir may be directed through one or more water injection conduits for injection into combustion chambers of an engine to reduce the combustion temperature. Heated coolant may flow through a coolant passage in heat exchange relationship with the second reservoir and heat the water in the second reservoir.In one example where the second reservoir and the first reservoir physically share space, heat may be transferred from the second reservoir to the first reservoir, melting at least some of the ice that has formed in the first reservoir. The melted ice / water from the first reservoir may flow into the vertically lower second reservoir, and water collected in the second reservoir may then be directed through the water injection line for injection to the engine.

[0013] In another example, the first reservoir and the second reservoir may each absorb heat from coolant flowing in coolant lines in heat exchange relationship with each of the reservoirs, thereby increasing the temperature in the reservoirs. At least some of the ice formed in the first reservoir may melt due to heat transfer from the coolant to the first reservoir. Water from the first reservoir may flow to the vertically lower second reservoir, which may then be used for injection into the engine's combustion chambers. Control of coolant flow to heat the water reservoir system may be based on input from a plurality of temperature sensors provided to a controller.Based on the signals from the plurality of temperature sensors, the controller may then adjust a position of one or more valves to regulate the flow of coolant to transfer heat to the water reservoir system, as described with respect to the . Fig. 1-5 are discussed below.

[0014] Fig. 1-4 show example devices with a relative arrangement of the various components. If they are shown directly touching or directly coupled to one another, then such elements may be referred to as directly touching or directly coupled to one another, respectively, in at least one example. Likewise, elements that are shown adjacent or proximate to one another may be adjacent or proximate to one another, respectively, in at least one example. As one example, components that share surfaces with one another may be referred to as sharing surfaces. In another example, elements that are positioned apart from one another with only a gap and no other components between them may be referred to as such, in at least one example.In another example, elements that are shown arranged above / below each other, on opposite sides of each other, or to the left / right of each other may be further referred to as such with respect to each other. Further, as shown in the figures, in at least one example, a topmost element or point of an element may be referred to as a "top" of the component, and a bottommost element or point of the element may be referred to as a "bottom" of the component. As used herein, top / bottom, upper / lower, over / under may refer to a vertical axis of the figures and may be used to describe the arrangement of elements of the figures with respect to one another. As such, elements shown above other elements are, in one example, arranged vertically above the other elements.Further, as another example, shapes of the elements depicted in the figures may be referred to as having these shapes (e.g., circular, straight, flat, curved, rounded, beveled, angled, or the like). Further, elements depicted crossing each other may be referred to as crossing elements or crossing each other in at least one example. Furthermore, an element shown inside another element or outside another element may be referred to as such in one example.

[0015] Fig. 1 illustrates an example vehicle system 101 including engine 10. Engine 10 may receive a primary fuel and additionally receive a secondary fluid. The secondary fluid may be water, which may be injected into the engine to reduce combustion temperature. In another example, the secondary fluid may be an alcohol-water mixture. Engine 10 may receive control parameters from a control system including controller 12 and input from a vehicle operator 130 via an input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. A cylinder (also referred to herein as a "combustion chamber") 14 of engine 10 may include combustion chamber walls 136 in which a piston 138 is disposed.Piston 138 may be coupled to a crankshaft 140, such that a reciprocating movement of the piston is translated into a rotational movement of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of the passenger vehicle via a transmission system. Furthermore, a starter may be coupled to crankshaft 140 via a flywheel to enable a starting process of engine 10.

[0016] Cylinder 14 may receive intake air via a series of intake air passages 142, 144, and 146. In addition to cylinder 14, intake air passage 146 may communicate with other cylinders of engine 10. In some embodiments, one or more of the intake passages may include a boost device, such as a turbocharger or a supercharger. For example, Fig. 1 shows the engine 10 configured with a turbocharger including a compressor 174 disposed between the intake ports 142 and 144 and an exhaust turbine 176 disposed along an exhaust passage 148. The compressor 174 may be powered at least partially via a shaft 180 by the exhaust turbine 176, with the boost device configured as the turbocharger. However, in other examples, such as when the engine 10 is provided with a mechanical supercharger, the exhaust turbine 176 may be omitted, where the compressor 174 may be powered by mechanical inputs from an electric motor or the internal combustion engine. A throttle 162 including a throttle plate 164 may be provided along an intake port of the engine for varying the flow rate and / or pressure of intake air provided to the cylinders of the engine.For example, the throttle 162 may be located downstream of the compressor 174, as shown in FIG. Fig. 1, or alternatively, it may be provided upstream of the compressor 174.

[0017] Exhaust passage 148 may receive exhaust gases from other cylinders of engine 10 in addition to cylinder 14. A variable voltage (VVs) oxygen sensor 128 is shown coupled to exhaust passage 148 upstream of emissions control device 178. VVs oxygen sensor 128 may be used to estimate and / or measure the oxygen content of exhaust gases emitted by the engine. The VVs oxygen sensor may also be used to estimate an amount of alcohol in the fuel burned in the engine and the ambient humidity.

[0018] The exhaust temperature may be measured by one or more temperature sensors (not shown) disposed within the exhaust passage 148. Alternatively, the exhaust temperature may be inferred based on engine operating conditions such as engine speed, load, air-fuel ratio (AFR), spark retard, etc. It should be understood that the exhaust temperature may alternatively be estimated using any combination of the temperature estimation methods listed herein.

[0019] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown as including at least one intake poppet valve 150 and at least one exhaust poppet valve 156 located in an upper region of cylinder 14. In some embodiments, each cylinder of engine 10, including cylinder 14, may include at least two intake poppet valves and at least two exhaust poppet valves located in an upper region of the cylinder.

[0020] The at least one intake poppet valve 150 may be controlled by the controller 12 via a cam actuation system 151 through cam actuation. Similarly, the at least one exhaust poppet valve 156 may be controlled by the controller 12 via a cam actuation system 153. The cam actuation systems 151 and 153 may each include one or more cams and utilize one or more of the following: cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which may be operated by the controller 12 to vary valve operation. The operation of the at least one intake poppet valve 150 and the at least one exhaust poppet valve 156 may be determined by valve position sensors (not shown) and / or camshaft position sensors 155 and 157, respectively.In alternative embodiments, the intake and / or exhaust valves may be controlled by electric valve actuation. For example, cylinder 14 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation systems, including CPS and / or VCT systems. In other embodiments, the intake and exhaust valves may be further controlled by a common valve actuator or actuation system, or a variable valve timing actuator or actuation system. Cam timing may be adjusted (by advancing or retarding the VCT system) to adjust engine dilution in coordination with EGR flow and / or direct injection of knock control fluid, thereby reducing EGR transients and improving engine performance.

[0021] Cylinder 14 may have a compression ratio that is the ratio of the volume when piston 138 is at bottom dead center to the volume at top dead center. Conventionally, the compression ratio is in the range of 9:1 to 10:1. However, in some examples where other fuels are used, the compression ratio may be increased. This may occur, for example, when using fuels with a higher octane rating or fuels with a higher latent heat of vaporization.

[0022] In some embodiments, each cylinder of engine 10 may include a spark plug 192 to initiate combustion. Ignition system 190 may provide an ignition spark to combustion chamber 14 via spark plug 192 in response to an ignition pre-ignition signal SA from controller 12 under selected operating modes. However, in some embodiments, spark plug 192 may be omitted, such as when engine 10 can initiate combustion through auto-ignition or by injecting fuel, which may be the case with some diesel engines.

[0023] In some embodiments, each cylinder of engine 10 may be configured with one or more fuel injectors. As a non-limiting example, cylinder 14 is shown as including a fuel injector 166. Fuel injector 166 is shown coupled directly to cylinder 14 to inject fuel directly therein proportional to the pulse width of a signal FPW received from controller 12 via electronic driver 168. In this manner, fuel injector 166 provides what is known as direct injection (hereinafter also referred to as "DI") of fuel into combustion cylinder 14. While Fig. 1 depicts the fuel injector 166 as a side injector, but it may also be positioned above the piston, such as near the position of the spark plug 192. Such a position may improve mixing and combustion when the engine is operating on an alcohol-based fuel, as some alcohol-based fuels have lower volatility. Alternatively, the fuel injector may be positioned above and near the intake valve to improve mixing.

[0024] The primary fuel may be delivered to the fuel injector 166 via a high-pressure fuel system 8, which includes one or more fuel tanks 78, fuel pumps, and a fuel rail. Alternatively, the fuel may be delivered at a lower pressure by a single-stage fuel pump, in which case the timing of the direct fuel injection during the compression stroke may be more limited than when using a high-pressure fuel system. Further, although not shown, the fuel tanks 78 may include a pressure transducer that provides a signal to the controller 12. It will be understood that in an alternative embodiment, the fuel injector 166 may be a port injector that provides fuel into the intake passage upstream of the cylinder 14.

[0025] A secondary fluid may be stored in a reservoir 76. In one example, the reservoir 76 may be coupled to a water injection device 77 via an insulated water injection line 75. In one example, the water injection device 77 may be configured to inject water into an air stream flowing along the intake passage between the compressor 174 and the combustion chamber, as shown in Fig. 1. In another example, water injector 77 may be directly coupled to the combustion chamber of cylinder 14 to inject water directly into the combustion chamber. In another example, reservoir 76 may be included in fuel system 8, where water may be injected along with fuel by a cylinder direct injector, for example, fuel injector 166. Water-containing reservoir 76 may also be coupled to a windshield wiper system (not shown) that may be used for windshield wiping purposes. It will also be understood that reservoir 76 may contain only water, a mixture of water and alcohol, or any other fluid that may be injected by an injector coupled to the engine.

[0026] The fuel and secondary fluid may be delivered to the cylinder by the injector during a single cylinder cycle. Furthermore, the delivered and / or relative amount of fuel or secondary fluid delivered by the injector may vary depending on operating conditions, such as air charge temperature. Furthermore, for a single combustion event, multiple injections of the delivered fuel may be performed per stroke. The multiple injections may be performed during the compression stroke, intake stroke, or any suitable combination thereof.

[0027] In some embodiments, the secondary fluid may be generated on-board the vehicle from exhaust condensate, charge air cooler condensate, air conditioning condensate drain, or rainwater drain. For example, the water in reservoir 76 may be self-generated from water draining from the exhaust charge air cooler, air conditioning and / or rainwater drain, etc. By self-generating the secondary fluid, the number of consumables in the vehicle system can be reduced.

[0028] Although not shown, it will be understood that the engine may further include one or more exhaust gas recirculation passages for diverting at least a portion of the exhaust gas from the engine exhaust to the engine intake. Thus, by recirculating a portion of the exhaust gas, dilution within the engine may be achieved, which may improve engine performance by reducing engine knock, peak cylinder combustion temperatures and pressures, throttle losses, and NOx emissions. The one or more EGR passages may include a LP EGR passage coupled between the engine intake upstream of the turbocharger compressor and the engine exhaust downstream of the turbine and configured to provide low-pressure EGR (LP).The one or more EGR passages may further include an HP EGR passage coupled between the engine intake downstream of the compressor and the engine exhaust upstream of the turbine and configured to provide high pressure (HP) EGR. In one example, HP EGR flow may be provided under conditions such as the absence of charge provided by the turbocharger compressor, while LP EGR flow may be provided during conditions such as the presence of charge from the turbocharger compressor and / or when an exhaust temperature is above a threshold. LP EGR flow through the LP EGR passage may be adjusted via an LP EGR valve, while HP EGR flow through the HP EGR passage may be adjusted via an HP EGR valve (not shown).

[0029] A coolant system (not shown) may circulate coolant through coolant lines along the engine 10 and through coolant lines past an exhaust gas recirculation cooler (not shown). The heated coolant flowing along coolant lines may transfer heat to various components of the vehicle, for example, to the reservoir 76, to a radiator (not shown), to a passenger compartment (not shown), etc. After heat transfer from the coolant to the various components of the vehicle, the coolant may flow back to the engine 10 to reabsorb heat. One or more pumps may be coupled to the coolant system to circulate the coolant.

[0030] In one embodiment, the coolant may flow into coolant channels that are in heat transfer relationship with a power electronics system of an HEV to capture waste heat and thereby cool the power electronics systems. The heated coolant may then flow to other components of the vehicle to transfer heat to warm the components. A coolant system of the vehicle for cooling various components, including a water reservoir system, is described in detail with reference to Fig. 4 described.

[0031] The control 12 is in Fig. 1 as a microcomputer including a microprocessor unit 106, input / output ports 108, an electronic storage medium for executable programs and calibration values, shown in this specific example as a read-only memory chip 110, random access memory 112, keep-alive memory 114 and a data bus.The controller 12 may receive various signals from sensors coupled to the engine 10 in addition to the signals previously discussed, including measuring the following: inducted mass air flow (MAF) from a mass air flow sensor 122; engine coolant temperature (ECT) from a temperature sensor 116 coupled to a cooling sleeve 118; a profile ignition pickup (PIP) signal from a Hall effect sensor 120 (or other type) coupled to a crankshaft 140; a throttle position (TP) from a throttle position sensor; and a manifold absolute pressure (MAP) signal from sensor 124. The engine speed signal RPM may be generated by the controller 12 from the PIP signal.The manifold pressure (MAP) signal from the manifold pressure sensor may be used to provide an indication of vacuum or pressure in the intake manifold. Further sensors may include fuel level sensors and fuel composition sensors coupled to the fuel tank(s) of the fuel system, and / or a knock sensor. In response to the signals received from the various sensors, the controller may operate various engine actuators. Example actuators include fuel injector 166, throttle 162, cam lobes 151 and 153, etc.

[0032] A storage medium of the read-only memory 110 may be programmed with computer-readable data representing instructions executable by the microprocessor 106 for performing the methods described below, as well as other variations anticipated but not explicitly enumerated. An example of a sequence that may be executed is described with respect to Fig. 5 explained.

[0033] Now, with reference to Fig. 2 illustrates a first embodiment of a water reservoir system 200 that can supply water to an injector of a water injection system, similar to the reservoir 76 for supplying the secondary fluid to the cylinder 14 of the engine 10 shown in Fig. 1. The water reservoir system 200 includes a first reservoir 202 and a second reservoir 208 fluidly coupled via a conduit 230. A coolant conduit 218 may enter the second reservoir 208, and coolant flowing through a heat exchange segment 219 of the coolant conduit 218 may be in heat exchange relationship with water 210 in the second reservoir 208. Heat exchange may occur between coolant in the heat exchange segment 219 and the water 210 in the second reservoir 208. At the end of the heat exchange segment 219, the coolant conduit 218 exits the second reservoir 208. In one example, the heat exchange segment 219 may not enter the second reservoir and may be external around a perimeter of the second reservoir. In another example, a portion of the heat exchange segment 219 may be internal and a portion of the heat exchange segment may be external to the second reservoir.The direction of coolant flow along the coolant line 218 and in the heat exchange segment 219 is indicated by arrows 220. The coolant line 218 may include a cylindrical hose or tube having an outer wall facing into the interior of the second vessel along the heat exchange segment 219 and an inner wall defining an internal volume through which coolant flows. The heat exchange segment 219 may be one of a variety of standard heat exchange units well known in the art, which may, for example, include multiple channels with external fins for distributing heat. The coolant in the coolant line 218 is kept separate from the water in the second vessel 208 throughout the heat exchange segment 219, and the coolant and water do not mix at any point in the second vessel.

[0034] The first container 202 may be vertically higher than the second container 208. In one example, the second container 208 may be located directly below the first container 202, as shown in Fig. 2. In one example, a bottom wall 203 may be positioned opposite a top wall 201 of the first container 202 above a top wall 205 of the second container 208. The bottom wall 203 of the first container may at least partially share surfaces with the top wall 201 of the second container. A first length L1 of the first container 202 may be greater than a second length L2 of the second container 208, wherein a portion of the second length L2 or all of the second length L2 of the top wall 205 of the second container 208 may share surfaces with at least a portion of the first length L1 of the bottom wall 203 of the first container. By sharing surfaces, heat may be transferred between the top wall of the second container and the bottom wall 203 of the first container 202.

[0035] In one example, a volume of the first container 202 may be greater than a volume of the second container 208. In another example, a volume of the first container and the second container may each be the same. In another example, the volume of the second container 208 may be greater than the volume of the first container 202.

[0036] The conduit 230 may extend from an opening in the bottom wall 203 of the first container and a corresponding opening in the top wall 205 of the second container, thereby establishing fluid communication between the first and second containers. The opening in the bottom wall 203 of the first container may be vertically higher than the opening in the top wall of the second container. Fluid may drip from the first container into the second container along the fluid conduit 230 due to gravity.

[0037] If the ambient temperature is below the freezing temperature of water, the water in the first reservoir may freeze and form ice 204. Therefore, the water supply from the first reservoir to the second reservoir through line 230 may be interrupted. The water 210 in the second reservoir may not freeze if warm coolant flows through the heat exchange segment 219 of the coolant line 218 and heats the water 210 in the second reservoir, even if the ambient temperature is below the freezing temperature of water. The second reservoir may be an insulated reservoir. The heated water from the second reservoir may flow through a water injection line 207 to an injector (not shown) for injecting water into a combustion chamber of the engine. The water injection line 207 may be insulated to maintain a temperature of the water flowing along the water injection line to the engine above the freezing temperature.In examples where the second reservoir is not insulated, the water in the second reservoir may also freeze under low-temperature conditions. However, when the engine is started, the coolant flowing through the coolant line can quickly melt the ice in the second reservoir because the reservoir has a relatively small volume.

[0038] The heat from the warm water 210 in the second container can be conducted through the divided surfaces between the top wall 205 of the second container 208 and the bottom wall 203 of the first container 202 to increase the temperature of the first container. The temperature increase in the first container can melt the ice 204 into water 206, which can accumulate along the bottom wall 203 of the first container.

[0039] The water 206 may drip through the line 230 and into the second container 208, where the collected water may be further heated based on the coolant flow and the coolant temperature along the heat exchange segment 219 of the coolant line 218. A temperature sensor 232 may measure a temperature of the water 210 in the second container, and a liquid level sensor 214 may measure the level of the water 210 and provide the signal inputs to a controller, for example, the controller 12 of Fig. 1, which in turn can regulate the coolant flow along the coolant line 218.

[0040] The coolant flow through the coolant line 218 may be controlled by a position of a coolant valve 216 along the coolant line 218. The coolant valve 216 may be coupled to the coolant line 218 upstream of the heat exchange segment 219 of the coolant line. The coolant valve 216 may be an electrically actuated valve. In another example, the coolant valve 218 may be a thermally actuated valve (such as a thermostatic valve). The coolant valve may be a two-position valve (open and closed). In another example, the coolant valve 216 may be a variable position valve from fully open to partially open to fully closed. In other embodiments, additional valves may be present along the coolant line.

[0041] A temperature sensor 212 may be coupled to the heat exchange segment 219 of the coolant line 218 downstream of the coolant valve 216. Additional temperature sensors may be coupled to the coolant line 218 to measure a temperature of the coolant in the coolant line 218. In one example, based on a temperature communicated to the controller from the temperature sensor 212 along the heat exchange segment 219 of the coolant line 218 and based on additional temperature input signals from other temperature sensors to the controller, the controller may regulate the position of the coolant valve 216 to increase or decrease the coolant flow through the coolant line 218. The regulation of the coolant flow through the coolant line is performed with respect to the Fig. 4 and Fig. 5 discussed below.

[0042] The coolant flowing through the coolant line 218 may be an engine coolant, for example a coolant that transfers waste heat from the engine 10 into Fig. 1. In another example, the coolant flowing through the coolant line 218 may absorb heat from the engine exhaust system. For example, the engine coolant may remove heat from hot exhaust gas flowing through an exhaust gas heat recovery (EGHR) system or hot exhaust gas flowing through an EGR cooler (not shown). In another example, the coolant may be the coolant flowing in coolant passages along an HEV power electronics system, where the coolant may remove heat from the HEV power electronics systems, resulting in a lowering of the HEV power electronics temperature. Heated coolant may flow away from the engine or the HEV power electronics along a direction indicated by an arrow 222 and may be directed to flow to the coolant line 218 or to a cooler (not shown) along the direction indicated by an arrow 224.Coolant flows through the coolant line 218 along direction 220 and, after heat exchange with the water 210 in the second reservoir, exits the second reservoir. Lower temperature coolant exiting the second reservoir may flow in a direction indicated by arrow 220 and may flow to the engine along the direction indicated by arrow 226, along with the coolant from the radiator, which flows along a direction indicated by arrow 228. The flow of coolant to and from the water reservoir system 200 is further described with respect to FIG. Fig. 4 discussed.

[0043] Now, with reference to Fig. 3 illustrates a second embodiment of a water container system 300. Some parts previously described in Fig. 2 are similarly numbered and are listed in Fig. 3 was not reintroduced.

[0044] In the water tank system 300, the first tank 202 and the second tank 208 may be located in vertically different planes, similar to the first embodiment of the water tank system 200 shown in Fig. 2. The second container may or may not be adjacent to the first container and may not be located directly below the first container. Thus, the bottom wall of the first container and the top wall of the second container may not share a surface. In one example, a conduit 330 may fluidly connect the first container to the second container. An inlet 331 of the conduit 330 may be coupled to the bottom wall 203, and an outlet 333 of the conduit 330 may be coupled to a top wall of the second container 208. In other examples, the conduit 330 may be coupled to other walls of the first container and / or the second container, where the inlet 331 of the conduit 330 may be vertically higher than the outlet 333.

[0045] Since the bottom wall 203 of the first container and the top wall 205 of the second container 208 do not share a surface, little or no heat is transferred between the first container and the second container through the walls. Instead, the ice 204 in the first container may be melted by heat transfer from a coolant to the first container. In addition to the heat exchange segment 219 of the coolant line 218 in the second container, a coolant line 332 may be in heat exchange relationship with the first container. The coolant line 332 may branch from the coolant line 218 downstream of the coolant valve 216 and upstream of the second container, as shown in Fig. 3 illustrates.

[0046] A coolant valve 328 may be coupled to the coolant line 332, where the coolant valve 328 may regulate the flow of coolant through the coolant line 332. In another embodiment, the coolant valve 328 and the coolant valve 216 may be replaced with a single multi-position coolant valve to direct the flow of coolant or stop the flow of coolant through the coolant line 332. The single coolant valve may also regulate the flow of coolant through the coolant line 218. In one example, a restriction 323 may be present in the coolant line 218 upstream of the second reservoir 208 to ensure a back pressure so that the coolant flows through the coolant line 332 when the coolant line 218 is also open to coolant flow.

[0047] A temperature sensor 326 may be coupled along a coolant line 332. The coolant may flow through the coolant valve 328 along the coolant line 332 in the direction indicated by the arrows. The coolant line 332 may be in physical contact along (an) outer surface(s) of the first container, and heat may be exchanged between the coolant in the coolant line 332 and the first container. In another example, the coolant line 332 may enter and exit the first container and may be configured to be in heat exchange relationship with the contents in the first container. The coolant line 332 may reconnect to the coolant line 218 at an intersection 334 before the second container after exchanging heat with the first container, as shown in Fig. 3. Thus, coolant flowing through coolant line 332 can be recirculated into coolant line 218 to flow to heat exchange segment 219.

[0048] When heat exchange occurs between the coolant in the coolant line 332 and the first tank, the ice 204 may melt and the water 206 may flow through the line 330 to the second tank to mix with the water 210. The coolant flow to and from the coolant line 218 in the water tank system 300 may be similar to the coolant flow described above with reference to Fig. 2 and will be further described in relation to Fig. 4 discussed.

[0049] In this way, according to the first, in Fig. 2, ice that has formed in the first container 202 due to a low ambient temperature can be melted by transferring heat from a warm coolant to the second container, and then heat can be transferred from the second container to the first container in the water container system 200, which is shown in Fig. 2. In a further embodiment, the first container may receive heat directly from a coolant flowing in a coolant line in heat exchange relationship with the first container, as shown in Fig. 3. The water created in the first tank by melting ice after heat transfer can flow through the line into the second tank by gravity. The water in the second tank can be further heated by coolant flowing in the heat exchange segment of the coolant line.

[0050] Thus, sufficient water may be available in the second reservoir for delivery through the water injection line to the injector coupled to the engine cylinder, even if ice has formed in the first reservoir due to a low ambient temperature. In one example, a check valve (not shown) may be present between the second reservoir and the water injection line, which may be in a closed position when no water is available in the second reservoir. Additionally, one or more temperature sensors may be coupled to the water injection line.

[0051] In one example, if water has been in the water injection line for an extended period of time, with the water in the water injection line being near the freezing temperature of water (for example, 3°F above the freezing temperature of 32°F), the water in the water injection line may be drained back into the second reservoir to prevent the water injection line from becoming blocked by ice formation. Once the temperature in the second reservoir is significantly above freezing and / or if the engine controller estimates a potential need for injected water in the next minute such that water will not be in the water injection lines for an extended period of time (for example, the engine is not shut down and is not still warming up), the flow of water from the second reservoir into the water injection line may resume.The position of one or more valves (not shown) along the water injection line can be controlled to drain the water from the water injection line back into the second container.

[0052] With reference to Fig. 4, a coolant system 400 is illustrated. The coolant system 400 may be coupled to a water reservoir system 450 of a water injection system. In Fig. 4, the water tank 450 is similar to the water tank system 300 of Fig. 3. In further embodiments, the water tank 450 is similar to the water tank system 200 shown in Fig. 2. The coolant flow along the coolant lines and the entry and exit points for the coolant lines are illustrated schematically, and the actual mechanical arrangement of the coolant lines and the actual entry and exit points of the coolant lines are not shown.

[0053] An engine 408 similar to the engine 10 from Fig. 1 may include coolant passages (not shown) in contact with various components of the engine 408 through which coolant may flow. A coolant line 409 may direct coolant to flow into the coolant passages in the engine 408. The coolant entering the engine 408 may have a lower temperature than a temperature of the engine 408. Heat from the various engine components may be transferred to the coolant flowing through the coolant passages, thereby cooling the engine. Coolant may also capture waste heat from the engine exhaust, for example, by flowing in coolant passages through an EGR cooler (not shown) or other suitable exhaust gas heat exchanger.The heated coolant may flow out of the engine through a coolant line 407, wherein a temperature of the coolant exiting the engine 408 may be higher than the temperature of the coolant entering the engine through the coolant line 409.

[0054] Warm coolant flowing through the coolant line 407 may be directed to heat one or more vehicle components 410. The one or more vehicle components 410 may include a passenger cabin heater core, one or more thermal storage devices, etc. Coolant may flow to the one or more vehicle components 410 through a coolant line 416 branching from the coolant line 407. A valve 415 may regulate the flow through the coolant line 416 to the one or more vehicle components 410. A position of the valve 415 may be controlled by a controller, for example, the controller 12 of Fig. 1, based on a signal from temperature sensors coupled to the one or more vehicle components. The coolant line 416 and valve 415 are only a schematic representation of the coolant flow along the one or more vehicle components. However, multiple coolant lines may branch off from the coolant line 407, and one or more coolant valves may regulate the coolant flow along each of the coolant lines through which coolant flows to the one or more vehicle components. In some examples, a system restriction, such as an orifice, may be used to control the distribution of coolant flow through various lines of the coolant system. This may replace any one or more of the aforementioned valves, or the restriction may be in addition to the valve(s).

[0055] Meanwhile, coolant flowing along the coolant line 407 may also flow to the water tank 450. A coolant line 464 may extend from the coolant line 407 and carry coolant to the water tank 450.

[0056] The water reservoir system 450 may include a first reservoir 452 in fluid communication through a conduit 468 with a second reservoir 454 similar to the water reservoir system 300 shown in Fig. 3. The coolant in the coolant line 464 may flow through the second reservoir, where coolant may transfer heat to the water 462 in the second reservoir 454 in a heat exchange segment 465. A liquid level sensor 436 may be coupled to the second reservoir. A temperature sensor may also be coupled to the second reservoir. Coolant flow from the coolant line 407 to the coolant line 464 may be regulated by a valve 417. The valve 417 may be an electrically actuated valve. In another example, the coolant valve 417 may be a thermally actuated valve (such as a thermostatic valve). The coolant valve may be a two-position valve (e.g., adjustable only to an open and closed position).In another example, the coolant valve 417 may be a variable-position valve ranging from fully open to partially open to fully closed. In other embodiments, additional valves may be present along the coolant line. A temperature sensor 434 may be coupled to a heat exchange segment 465 of the coolant line 464 downstream of the coolant valve 417.

[0057] Coolant may flow to the first reservoir through a coolant line 422, wherein the coolant line 422 may branch off from the coolant line 464, as shown in Fig. 4. Coolant flow to coolant line 432 from coolant line 464 may be controlled by a valve 421. A temperature sensor may be coupled to coolant line 432. In another example, a coolant line to the first reservoir may not branch off from coolant line 464, but may originate directly from coolant line 407.

[0058] The coolant line 422 may be in heat exchange relationship with a bottom wall of the first container 452, transferring heat from the coolant to melt ice formed in the first container due to a low ambient temperature. The melted ice collects as water 456 along the bottom wall 453 and may flow through the fluid line 468 to the second container 454.

[0059] Coolant flowing through coolant line 407 beyond water reservoir 450 may flow through coolant line 422 to a radiator 420. Coolant flow through coolant line 422 to radiator 420 may be controlled by a valve 419 along coolant line 422.

[0060] Coolant flowing through radiator 420 may be cooled in heat exchange relationship with the ambient air, and after heat is transferred to the ambient air, the coolant flows from the radiator through a coolant line 418 to flow to the engine for cooling the engine. The coolant flowing along coolant line 418 to the engine 408 may have a lower temperature than the coolant flowing from the engine in coolant line 407.

[0061] Coolant line 418 may also receive low-temperature coolant from additional coolant lines. Coolant exiting the second reservoir of the water reservoir 450 along a coolant line 466 may flow back into the coolant line 418, which carries coolant to the engine. Coolant flowing after transferring heat to the one or more components of the vehicle 410 may flow through a coolant line 414 that joins the coolant line 418. Thus, after transferring heat to various systems, coolant may flow through the coolant line 418 and coolant line 409 to the engine 408 to cool the engine and recover heat from the engine exhaust.

[0062] In one example, the coolant may recover heat from the HEV power electronics system instead of the engine 408. The heat recovered by flowing the coolant through cooling channels in close proximity to the HEV power electronics system may lower a temperature of the HEV power electronics systems. The warmer coolant after absorbing heat from the power electronics may then be used to warm various components of the vehicle, as described above.

[0063] In one example, the water tank system 200 may be coupled to the coolant line 464, wherein the coolant flow through the heat exchange segment of the coolant line may transfer heat to the water in the second tank. The first tank and the second tank may at least partially share surfaces, as shown in Fig. 2, wherein heat can be transferred from the second container to the first container and ice in the first container can melt. The water from the melted ice in the first container can drip through the line 230 into the second container as described above with respect to Fig. 2. Coolant flow through the second reservoir can be controlled by controlling the position of valve 417. In this embodiment, no coolant flow can be directed to the first reservoir. Water from the second reservoir can flow through water injection line 463 to be injected into the engine. A temperature sensor can be coupled to the water injection line.

[0064] Thus, the waste heat absorbed by the coolant from the engine or HEV power electronics systems can be transferred to the water reservoir system to prevent ice formation when the ambient temperature is low, thereby maintaining the water supply to the water injection system coupled to the engine. Additionally, heat energy from the coolant can also be transferred to other components of the vehicle to increase their temperature. The coolant has a lower temperature after the heat energy is transferred to various components than it was before the heat energy was transferred. The low-temperature coolant can then be redirected back to the engine to absorb waste heat.In this way, the coolant in the vehicle's coolant system can be used in an energy-efficient manner for both cooling functions (the engine, the HEV power electronics) and heating functions (the water tank, other vehicle components).

[0065] A method 500 for controlling the coolant flow to a water tank system is shown in a flowchart in Fig. 5. The coolant may transfer heat to the water reservoir system when the ambient temperature is below the freezing temperature of water to prevent the water in the water reservoir from freezing and thereby keep the water supply in the water reservoir system liquid for injection into an engine. In one example, method 500 may direct a coolant flow to the water reservoir system 200 (illustrated in Fig. 2) or to the water tank system 300 (illustrated in Fig. 3) along the coolant circuit 400, which is Fig. 4. The water reservoir may include the first reservoir 202, which is vertically higher than the second reservoir 208 and fluidly connected to the second reservoir 208. A coolant flow along the coolant line 218 through the second reservoir may be controlled by the coolant valve 216 along the coolant line to heat the water in the second reservoir. Heat may be transferred from the second reservoir to the first reservoir as it flows between the first and second reservoirs, as shown in Fig. 2, divide surfaces. In another embodiment, the first container may receive heat from the coolant flowing through the coolant conduit in heat exchange relationship with the first container, as shown in Fig. 3 and Fig. 4 illustrates.

[0066] Instructions for carrying out the method 500 and the other methods contained herein may be executed by a controller, for example, the controller 12 of Fig. 1, 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. 2 and Fig. 3 described temperature sensors 212 and 232 and the fluid level sensor 214. The controller may employ engine actuators of the engine system to determine a position of one or more valves, such as the coolant valve 216, according to the methods described below. Fig. 2 and Fig. 3, which regulate a coolant flow to heat the water in the water tank system.

[0067] Method 500 begins at 502 by determining engine operating conditions based on feedback from a variety of engine sensors. Engine operating conditions may include, but are not limited to, engine speed and load, engine temperature, exhaust gas temperature, engine coolant temperature, water temperature in the second water reservoir of the water injection system, fluid level in the water reservoir of the water injection system, engine knock, exhaust oxygen concentration, etc.

[0068] At 504, a method 500 determines a temperature of water in the second tank (T_WIT) of the water tank system. The second tank may be the second tank 208 (illustrated in Fig. 2 and Fig. 3). A temperature sensor coupled to the second tank can transmit the water temperature T_WIT to the controller, for example, the temperature sensor 232 from Fig. 2 and Fig. 3 of the control 12 ( Fig. 1) Provide T_WIT.

[0069] At 506, method 500 determines the coolant temperature T_CT at the heat absorption source by the coolant. In one example, the heat absorption source for the coolant may be the engine, where the coolant may absorb heat, including hot engine exhaust, to cool the engine and the exhaust. In another example, the heat absorption source for the coolant may be the HEV power electronics system, where the coolant absorbs heat from the power electronics to cool the power electronics system. One or more temperature sensors, such as temperature sensor 116 of Fig. 1, can be coupled to the coolant system at the heat absorption source and can provide T_CT as an input signal to the controller.

[0070] At 508, method 500 determines the temperature of the coolant near the second reservoir, for example, in the heat exchange segment of the second reservoir, T_CT-WIT. In one example, temperature sensor 212 associated with heat exchange segment 219 of coolant line 218 may Fig. 2 and Fig. 3 is coupled, pass T_CT-WIT to the controller.

[0071] At 509, method 500 evaluates whether T_WIT is below a first threshold temperature. The first threshold temperature may be a few degrees (e.g., 6°F) higher than the freezing temperature of water (32°C). In one example, the first threshold may be 38°F. At 509, method 500 also determines whether T_CT is above a second threshold temperature, where the second threshold temperature is higher than the first threshold temperature. In one example, the second threshold may be 50°F higher than the first threshold. At 509, method 500 also determines whether T_CT-WIT is below a third threshold, where the third threshold is above the first threshold and above the second threshold. In one example, T_CT-WIT may be near the boiling temperature of water (e.g., 212°F).

[0072] If T_WIT is not below the first threshold, T_CT is not above the second threshold, and / or T_CT-WIT is above the third threshold, at 509 the method proceeds to 526, where the coolant valve is maintained in the closed position such that no coolant flows to the water reservoir. If T_WIT is above the first threshold temperature (e.g., 100°F), the water in the second reservoir is not near freezing temperature. Thus, no coolant flow is required to heat the water. If T_CT is not above the second threshold at 509, the coolant does not have sufficient thermal energy to heat the water in the second reservoir when water heating is desired.

[0073] Additionally, if T_CT-WIT is not below the third threshold, the water in the second reservoir may begin to boil due to the excessive coolant temperature in the heat exchange segment, which may be transferred to the water. Therefore, the closed coolant valve position is maintained at 526. Method 500 then returns.

[0074] In one example, if the water in the second reservoir is at 38°F and the temperature of the engine coolant flowing through the heat exchange segment of the coolant line (T_CT-WIT) passing through the second reservoir is near the boiling point of 212°F, localized boiling / evaporation of the water at the surface of the heat exchange segment may occur for a short period of time (e.g., more than one minute) before the heat is dissipated by the water mass in the second reservoir to raise the reservoir temperature above 42°F. In at least some examples, such boiling may be undesirable because it could lead to heat exchanger degradation or other problems.

[0075] If a coolant in the heat exchange segment of the water tank is too hot, the flow of coolant through the coolant line leading to the heat exchange segment in the second tank can be stopped by placing the coolant valve in a closed position. While the coolant valve is in the closed position, hot coolant in the heat exchange segment transfers some of the heat to the water in the water tank and cools down. In one example, the coolant valve can be operated based on the measured temperature T_CT-WIT in a duty cycle where the coolant valve can be in an open position 10% of the time and in the closed position 90% of the time to control the rate at which heat is transferred from the heat exchange segment of the coolant line to the water in the second tank.

[0076] However, at 509, if T_WIT is below the first threshold, T_CT is above the second threshold, and T_CT-WIT is below the third threshold, the method proceeds to 510, where the coolant valve is opened to direct a flow of coolant through the coolant line in heat exchange relationship with the second water reservoir. The coolant flowing through the coolant line transfers heat to heat the water in the second reservoir. Because T_WIT is below the first threshold, heating the water reservoir prevents ice formation because ice can shut off the water supply to the water injector coupled to the engine. If T_CT is above the second threshold, this indicates that there is sufficient heat in the coolant that can be transferred through the coolant line to heat the water in the second reservoir.However, because T_CT-WIT is not above the third threshold, the coolant in the heat exchange segment of the coolant conduit cannot transfer more than the desired heat to the water in the second tank, and thus, the water in the second tank does not boil and locally vaporize due to excessive heat transfer from the heat exchange segment of the coolant conduit. In one example, as indicated at 512, opening the coolant valve to allow heat transfer to the first tank may occur through the second tank, where the first tank is vertically above the second tank and at least partially shares surfaces with a wall of the second tank (such as the water tank system 200 shown in FIG. Fig. 2). As the coolant flow through the coolant line increases a T_WIT in the second vessel, heat can be conducted from the second vessel through the split-surface walls to the first vessel, thereby increasing the temperature in the first vessel.

[0077] At 516, the coolant flowing through the heat exchange segment of the coolant line heats the water in the second reservoir. The water in the second reservoir is now available for injection into the engine through the water injection line. The temperature of the coolant in the heat exchange segment of the coolant line (T_CT-WIT) may be monitored, and the coolant valve may be closed when T_CT-WIT rises above the third threshold.

[0078] At 518, method 500 determines whether the second reservoir water level is above a threshold level. The threshold level may indicate a minimum volume of water in the second reservoir to enable delivery through the water injection line to the water injection injector coupled to the engine. The water level may be determined from a liquid level sensor coupled to the second reservoir (for example, liquid level sensor 214 coupled to the second reservoir 208 in Fig. 2 and Fig. 3), and the water level signal can be passed on to the control system.

[0079] If the water level is not above the threshold level at 518, there is insufficient water available in the second reservoir to be directed to the water injector coupled to the engine. Method 500 proceeds to 528, where coolant flow continues to the second reservoir through the open coolant valve to transfer heat from the coolant to the second reservoir and heat is transferred to the first reservoir. In one example, as indicated at 530, heat transfer to the first reservoir may occur through the second reservoir, where the first reservoir is vertically above the second reservoir and at least partially shares surfaces with a wall of the second reservoir (such as the water reservoir system 200 shown in Fig. 2). In another example, as indicated at 532, heat transfer to the first reservoir may occur by opening a second coolant valve to direct warm coolant through a second coolant line in heat exchange relationship with the first reservoir. The coolant in the second coolant line may transfer heat to the first reservoir (such as in the water reservoir system 300 shown in Fig. 3 is illustrated).

[0080] If the coolant continues to transfer heat to the water reservoirs, method 500 proceeds to 534, where the melted ice drips as water from the first reservoir into the second reservoir, increasing the water level in the second reservoir for water injection. Method 500 then returns to 518 to evaluate whether the water level in the second reservoir is above the threshold level.

[0081] Method 500 proceeds to 520 if the water level in the second reservoir is above the threshold level at 518 to determine if T_WIT is below the first threshold temperature. If so, method 500 proceeds to 524, where the cooling valve is maintained in the open position to direct coolant to the first reservoir to continue heating the water in the first reservoir. Method 500 then returns.

[0082] However, at 520, if T_WIT is not below the first threshold, this indicates that the water in the second reservoir is sufficiently heated. Method 500 proceeds to 522, where the coolant valve is closed to stop coolant flow through the second reservoir, as the water no longer needs to be heated. In one example, the coolant valve may be closed when T_WIT is a few degrees above the first threshold (e.g., the first threshold may be 38°F and the coolant valve may be closed when T_WIT is 42°F). The heated water may be directed through the water injection line from the first reservoir into the water injection injector coupled to the engine. Method 500 then returns.

[0083] In this way, the coolant recovering waste heat from the engine or HEV power electronics system can transfer the heat to the water reservoir system to maintain a water supply in the second reservoir for water injection into the engine, even when the ambient temperature is at or below the freezing temperature of water. The water in the second reservoir is heated by the coolant flowing through the coolant conduit and transferring heat to the water. The first reservoir, which may be vertically higher than the second reservoir and fluidly coupled to the second reservoir, can be heated by heat transfer from the second reservoir through physical contact between the first and second reservoirs. Alternatively, the first reservoir can be heated by coolant flowing through a second coolant conduit that is in heat exchange relationship with the first reservoir.Heat transfer to the first reservoir can melt ice in the first reservoir, and the melted ice (water) drips into the second reservoir due to gravity. Thus, even at low ambient temperatures, a water supply can be available through the water injection line in the second reservoir for injection into the engine.

[0084] The technical effect of transferring heat from a coolant to a water reservoir of a water-injection system involves maintaining a water supply in the water reservoir even at low ambient temperatures. Utilizing waste heat recovered by the coolant, either from an engine or from a HEV power electronics system, and transferring it to the water reservoir provides an energy-efficient system for using the coolant for both cooling and heating functions in the vehicle. Maintaining a water supply in the water reservoir for water injection even at low ambient temperatures enables water injection to reduce the combustion temperature in the engine cylinders, thereby improving fuel efficiency. Additionally, water injection reduces the formation of combustion byproducts such as NOx, CO, etc., thereby improving vehicle emissions.

[0085] An exemplary water injection system includes a first reservoir fluidly coupled to a second reservoir, the second reservoir positioned at a vertically lower level than the first reservoir, the second reservoir fluidly coupled to a water injector of an engine, a first coolant conduit in heat exchange relationship with the second reservoir, and a first coolant valve along the first coolant conduit, upstream of the second reservoir, configured to regulate the flow of coolant through the first coolant conduit. The heat exchange relationship may include transferring heat from the coolant in the first coolant conduit through a wall of the first coolant conduit to the second reservoir without mixing the coolant with the contents of the second reservoir.A first example of the water injection system includes where a first volume of the first container is greater than a second volume of the second container. A second example of the water injection system includes the first example and further includes where a bottom wall of the first container and a top wall of the second container at least partially share surfaces with each other. A third example of the water injection system optionally includes one or more of the first and second examples and further includes where an inlet of a fluid conduit fluidly coupling the first container to the second container is located in the bottom wall of the first container and an outlet of the fluid conduit is located in the top wall of the second container.A fourth example of the water injection system optionally includes one or more of the first to third examples and further includes a second coolant line including a second coolant valve, the second coolant line being in heat exchange relationship with the first reservoir. A fifth example of the water injection system optionally includes one or more of the first to fourth examples and further includes the second coolant line originating from a branching point along the first coolant line downstream of the first coolant valve and fluidly connecting the second coolant line, after heat exchange with the first reservoir, to the first coolant line upstream of the second reservoir and downstream of the branching point.A sixth example of the water injection system optionally includes one or more of the first through fifth examples, and further includes the first coolant conduit passing through an interior volume of the second reservoir. A seventh example of the water injection system optionally includes one or more of the first through seventh examples, and further includes the first coolant conduit located along a bottom surface of the second reservoir. An eighth example of the water injection system optionally includes one or more of the first through seventh examples, and further includes the coolant being an engine coolant. A ninth example of the water injection system optionally includes one or more of the first through eighth examples, and further includes the coolant being a power electronics coolant of a hybrid electric vehicle.A tenth example of the water injection system optionally includes one or more of the first through ninth examples, and further includes a controller having computer-readable instructions stored on non-transitory memory to open the first coolant valve in response to a temperature in the second reservoir being below a first threshold. An eleventh example of the water injection system optionally includes one or more of the first through tenth examples, and further includes the controller further including instructions to open the first coolant valve in response to a temperature of a coolant at a heat recovery source for heating the coolant being above a second threshold.

[0086] An example method including opening a first coolant valve in response to a temperature of a first reservoir being below a first threshold and a temperature of coolant at a heat recovery source being above a second threshold, and coolant flowing through the first coolant conduit in heat exchange relationship with the first reservoir, the first reservoir being fluidly coupled to a second reservoir and a water injector of an engine, and closing the first coolant valve in response to the temperature of the first reservoir being above the first threshold, thereby stopping the flow of coolant through the first coolant conduit. A first example of the method includes the first threshold being lower than a second threshold.A second example of the method of the first example optionally includes the heat recovery source being an engine. A ninth example of the water injection system optionally includes one or more of the first through eighth examples and further includes the coolant being a power electronics coolant of a hybrid electric vehicle. A third example of the method optionally includes one or more of the first and second examples and further includes adjusting a position of a second coolant valve along a second coolant conduit in heat exchange relationship with the second reservoir.A fourth example of the water injection system optionally includes one or more of the first and second examples and further includes adjusting the position of the second coolant valve, comprising opening the second coolant valve in response to a water level in the first reservoir being below a threshold water level to direct the coolant flow to the second coolant conduit through the second coolant valve.

[0087] Another example system includes a first reservoir fluidly coupled to a second reservoir, the second reservoir fluidly coupled to a water injection line to an engine, a first coolant line in heat exchange relationship with the second reservoir, a first coolant valve along the first coolant line configured to regulate the flow of coolant through the first coolant line, and a second coolant valve along the second coolant line configured to regulate the flow of coolant through the second coolant line. A first example of the system includes the second reservoir being vertically lower than the first reservoir and sharing no surfaces with the first reservoir.

[0088] It should be noted that the example control and estimation routines included herein may be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein may be stored as executable instructions on non-volatile memory and executed by the control system, including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. Thus, various illustrated acts, operations, and / or functions may be performed in the order illustrated, in parallel, or in some cases, may be omitted.Likewise, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but rather is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, the described acts, operations, and / or functions may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the internal combustion engine control system, in which the described acts are performed by executing the instructions in a system including the various internal combustion engine hardware components in combination with the electronic controller.

[0089] It is understood that the configurations and routines disclosed herein are exemplary in nature and that these specific embodiments are not to be considered limiting, as numerous variations are possible. For example, the above technology may be applied to V-6, I-4, I-6, V-12, horizontally opposed 4-cylinder, and other internal combustion engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and configurations, and other features, functions, and / or characteristics disclosed herein.

[0090] The following claims particularly set forth certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements and neither requiring nor excluding two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application.Such claims, whether broader, narrower, equal, or different in scope than the original claims, are further considered to be included within the subject matter of the present disclosure.

Claims

[1] Water injection system comprising: a first container (202, 452) containing a fluid including water, the first container (202, 452) being only directly fluidically coupled to a second container (208, 454), the second container (208, 454) being positioned at a vertically lower level than the first container (202, 452), the second container (208, 454) being fluidically coupled to a fluid injection device of an engine (10, 408); a first coolant conduit (218, 464) in heat exchange relationship with the second container (208, 454); and a first coolant valve (216, 417) along the first coolant line (218, 464) configured to regulate a flow of a coolant through the first coolant line (218, 464), wherein the first coolant valve (216, 417) is opened in response to a temperature of the first container (202, 452) being below a first threshold and a temperature of a coolant at a heat recovery source being above a second threshold, and wherein the first coolant valve (216, 417) is closed in response to the temperature of the first container (202, 452) being above the first threshold, thereby stopping the flow of coolant through the first coolant line (218, 464); wherein the first coolant line (218, 464) is fluidly connected to a coolant system of power electronics of a hybrid electric vehicle. [2] The water injection system of claim 1, wherein a first volume of the first container (202, 452) is greater than a second volume of the second container (208, 454). [3] The water injection system of claim 1, wherein a first wall of the first container (202, 452) and a second wall of the second container (208, 454) at least partially share surfaces with each other. [4] Water injection system according to claim 3, wherein an inlet (331) of a fluid line (330, 408) fluidly coupling the first container (202, 452) to the second container (208, 454) is located in the first wall of the first container (202, 452) and an outlet (333) of the fluid line (330, 408) is located in the second wall of the second container (208, 454). [5] The water injection system of claim 1, further comprising a second coolant line (332, 422) including a second coolant valve (328, 421), the second coolant line (332, 421) being in heat exchange relationship with the first reservoir (202, 452). [6] The water injection system of claim 5, wherein the second coolant line (332, 422) originates from a branching point along the first coolant line (218, 464), and the second coolant line (332, 422), after heat exchange with the first reservoir (202, 452), is fluidly connected to the first coolant line (218, 464) upstream of the second reservoir (208, 454) and downstream of the branching point. [7] The water injection system of claim 1, wherein the first coolant line (218, 464) passes through an interior volume of the second container (208, 454). [8] The water injection system of claim 1, wherein the first coolant line (218, 464) is located along a lower surface of the second reservoir (208, 454). [9] The water injection system of claim 1, wherein the first coolant line (218, 464) is fluidly connected to an engine coolant system. [10] The water injection system of claim 1, further comprising a controller (12) having computer-readable instructions stored on non-volatile memory to open the first coolant valve (216, 417) in response to a temperature in the second reservoir (208, 454) being below the first threshold. [11] The water injection system of claim 10, wherein the controller (12) further includes instructions to open the first coolant valve (216, 417) in response to a temperature of a coolant at a heat recovery source for heating the coolant being above a second threshold. [12] Method comprising: Opening a first coolant valve (216, 417) in response to a temperature of a first reservoir (202, 452) containing a fluid including water being below a first threshold and a temperature of a coolant at a heat recovery source being above a second threshold, wherein coolant flows through the first coolant line (218, 464) in heat exchange relationship with the first reservoir (202, 452), the first reservoir (202, 452) is only directly fluidically coupled to a second reservoir (208, 454), the second reservoir (208, 454) being positioned vertically below the first reservoir (202, 452), and the second reservoir (208, 454) being fluidly coupled to a fluid injector of an engine (10, 408); and Closing the first coolant valve (216, 417) in response to the temperature of the first container (202, 452) being above the first threshold, thereby stopping the flow of coolant through the first coolant line (218, 464); wherein the heat recovery source is an engine (10, 408) or power electronics of a hybrid electric vehicle. [13] The method of claim 12, further comprising adjusting a position of a second coolant valve (328, 421) along a second coolant line (332, 422) in heat exchange relationship with the second reservoir (208, 454), wherein adjusting the position of the second coolant valve (328, 421) comprises opening the second coolant valve (328, 421) in response to a water level in the first reservoir (202, 452) being below a threshold water level to direct coolant flow to the second coolant line (332, 422) through the second coolant valve (328, 421).

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