System and method for recovering thermal energy in the cylinder and controlling the cylinder temperature

Abstract

Procedure that includes the following: Individual injection of fluid into several pipe arrangements (210), wherein each pipe arrangement (210) of the several pipe arrangements (210) contains one or more pipes that pass through a combustion chamber (214) of a corresponding engine cylinder (215) in a region of a head of the engine cylinder (215), wherein an amount of the fluid individually injected into each pipe arrangement (210) is based on a temperature of the corresponding engine cylinder (215); and Recovery of thermal energy from the injected fluid after it has passed through each tube arrangement (210).

Description

Technical area

[0001] This description relates generally to methods and systems for recovering thermal energy from the exhaust gases of a combustion cylinder of a motor vehicle. Background / Brief description

[0002] Internal combustion engines generate motive power (e.g., mechanical work) by burning fossil fuels within the engine's combustion chambers. During combustion, the hot gases produced are used to drive a piston and / or perform other work within the vehicle as they expand. The hot exhaust gases then flow through a vehicle's exhaust system before escaping into the atmosphere. A byproduct of fossil fuel combustion is heat. Only a small fraction of the energy present in the chemical compounds of fossil fuel is used to propel the vehicle forward, and much of the energy is lost in the form of unusable, entropic heat. The combustion of fossil fuels within the combustion chambers occurs in a constantly repeating and cyclical manner and can therefore be considered a type of thermodynamic cycle.By recovering and subsequently utilizing the heat generated as a by-product during the step or steps of the combustion cycle (e.g., combustion), it may be possible to recover thermal energy from the exhaust gases in the internal combustion engine to improve fuel economy.

[0003] As one example, a method for recovering and utilizing excess thermal energy from exhaust gases in an internal combustion engine may include utilizing a bottom cycle, such as a Rankine cycle, to generate mechanical or electrical power, referred to herein as work, from the entropic heat of the exhaust gases generated during combustion. In particular, the waste heat of the exhaust gases may be transferred to a working fluid to create a vapor that can be used to generate work within the motor vehicle, thereby improving fuel economy. The working fluid vapor is then condensed into a liquid form to re-enter and restart the thermodynamic Rankine cycle. An exemplary approach is presented by Gleich et al. in DE 10 2012 015 927 A1.Therein, Gleich discloses an exhaust gas heat exchanger installed in a combustion cylinder liner, wherein the liner contains a working fluid that can be converted into steam to generate work in the vehicle in the manner of a Clausius-Rankine cycle.

[0004] Furthermore, US 2014 / 0 261 257 A1 describes a cooling system for an internal combustion engine. Furthermore, DE 20 2015 100 531 U1 describes an internal combustion engine with a split cooling system and cylinder deactivation.

[0005] However, the inventors have recognized potential problems with such systems. For example, cylinders have different temperatures depending on the vehicle's operating conditions, and uniformly cooling cylinders using the same amount of working fluid in each cylinder liner when one or more cylinders are already at a relatively cool temperature can have negative effects on combustion efficiency and fuel economy.

[0006] In one example, the problems described above may be addressed by a method comprising individually injecting fluid into a plurality of tubes of a tube array, where each tube of the plurality of tubes passes through a combustion chamber of a corresponding engine cylinder in a region of a head of the engine cylinder, based on a temperature of the engine cylinder, and recovering heat energy from the injected fluid after it has flowed through each tube. In this way, the fluid, which may be referred to herein as working fluid, may be converted from a liquid to a gaseous state by waste heat in the exhaust gases to perform additional work within the motor vehicle in a manner tailored to each individual combustion cylinder, thereby improving combustion efficiency and fuel economy.

[0007] As one example, a controller may be used to monitor the temperature of each combustion cylinder and alter the amount and / or timing of fluid injected into the corresponding engine cylinder so that the cylinder's temperature is maintained within a combustion threshold range. For example, if an engine cylinder is running hotter than its counterparts, more fluid may be injected into the piping network running through that cylinder to assist in cooling it. Alternatively, if a particular engine cylinder is running below a temperature threshold, less or no fluid may be injected into the piping network running through that cylinder to increase the cylinder's temperature to bring it into line with the other engine cylinders.

[0008] The above advantages and other advantages and features of the present description will become clear from the following detailed description taken alone or in conjunction with the accompanying drawings.

[0009] It should be understood that the above 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 key features or essential features of the claimed subject matter, the scope of which is defined solely by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve the disadvantages noted above or elsewhere in this disclosure. Brief description of the drawings Fig. 1 is a block diagram of an engine system in a vehicle. Fig. Figure 2 shows an exemplary in-cylinder thermal energy recovery system. Fig. Figure 3 shows a flow diagram illustrating a method for utilizing fluid injectors and an in-cylinder Rankine cycle thermal energy recovery system in response to engine operating conditions. Fig. Figure 4 shows a graph illustrating the relationship between individual engine cylinder temperatures and fluid injection amounts. Detailed description

[0010] The following description relates to systems and methods for recovering waste heat from exhaust gases in an engine system, such as the one described in Fig. 1 shown engine system. Fig. Figure 2 shows an exemplary device for converting the waste heat contained in exhaust gases into work within a vehicle. As shown in Fig. 2, a combustion cylinder, here designated cylinder, may be equipped with a tube assembly located in the cylinder head region, which may then receive fluid injection via a fluid injector located upstream of the cylinder. As shown in Fig. As shown in Figure 2, the tube assembly can be in thermal communication with the heat of the exhaust gases generated during combustion in the cylinder via the wall of the tube assembly, and the injected fluid can then be vaporized by the ambient heat of the immediate environment. The vaporized fluid can then be used to perform additional work within the vehicle before undergoing condensation and re-entering the tube assembly. Fig. 3 shows a flowchart illustrating a method for controlling the amount of fluid (e.g., working fluid) injected into each cylinder of the engine in response to the temperatures of the individual cylinders and the operating conditions of the vehicle. The flowchart of Fig. Figure 3 further illustrates how the injected fluid can capture waste heat from exhaust gases to perform additional work in the vehicle. The diagram of Fig. Figure 4 shows how the fluid (e.g., working fluid) of the described embodiment can be used to control the temperatures of the engine cylinders. In particular, Fig. 4 illustrates the inversely proportional relationship between a temperature of a particular cylinder and the amount of fluid injected into the particular cylinder. In this way, fluid injection into a pipe assembly passing through the cylinders of the engine can serve the dual purpose of extracting additional work from the waste heat of the exhaust gases and individually monitoring and regulating the temperatures of individual cylinders to thereby increase fuel economy.

[0011] Fig. 1 schematically illustrates one cylinder of a multi-cylinder engine 10, which may be included in a propulsion system of an automobile. The engine 10 may be controlled at least partially by a control system including a controller 12 and by input from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. The vehicle may include a clutch 135. In one example, the engine 10 may be at least partially controlled by the controller 12, and inputs from a vehicle operator 132 may be provided via a clutch pedal 133 and a clutch pedal sensor 131. Input to the controller 12 may come from a clutch pedal sensor 131. The clutch pedal sensor 131 detects the position of the clutch pedal 133.The position of the clutch pedal 133 determines the engagement state of the clutch 135. The state of the clutch pedal is used in the example given in this description because it is a convenient way to describe monitoring the engagement state of the clutch. However, it should be understood that instead of sensing the clutch pedal position, other methods could be used to monitor and provide feedback on the clutch engagement state. In another example, the clutch 135 may be an automatic clutch. As such, the controller 12 may send a signal to position the clutch 135 to different positions based on engine operating conditions. As explained in more detail below, the clutch 135 may include a clutch actuator that controls the engagement of the clutch 135 from another element (such as a shaft coupled to a turbine, as shown in FIG. Fig. 2) to actuate and move the clutch 135.

[0012] The combustion chamber (i.e., cylinder) 30 of the engine 10 may include combustion chamber walls 32 with a piston 36 positioned therein. In some embodiments, the face of the piston 36 within the cylinder 30 may have a bowl. The piston 36 may be coupled to the crankshaft 40 such that reciprocating motion of the piston is converted to rotational motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate gear system. Further, a starter motor may be coupled to the crankshaft 40 via a flywheel to enable starting of the engine 10. Furthermore, the crankshaft 40 may be driven by the steam of the present embodiment, as described in more detail in subsequent figures.

[0013] Combustion chamber 30 may receive intake air from intake manifold 44 via intake conduit 42 and may exhaust combustion gases via exhaust conduit 48. Intake manifold 44 and exhaust conduit 48 may selectively communicate with combustion chamber 30 via a respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may include two or more intake valves and / or two or more exhaust valves.

[0014] The intake valve 52 may be controlled by the controller 12 via an electric valve actuator (EVA) 51. Likewise, the exhaust valve 54 may be controlled by the controller 12 via an EVA 53. Alternatively, the variable valve actuator may be electro-hydraulic or any other conceivable mechanism for enabling valve actuation. Under some conditions, the controller 12 may vary the signals supplied to the actuators 51 and 53 to control the opening and closing of the respective intake and exhaust valves. The position of the intake valve 52 and the exhaust valve 54 may be determined by valve position sensors 55 and 57, respectively.In alternative embodiments, one or more intake and exhaust valves may be actuated by one or more cams and may utilize cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems to vary valve operation. For example, cylinder 30 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation, including CPS and / or VCT systems.

[0015] The fuel injector 66 is shown coupled directly to the combustion chamber 30 to inject fuel directly therein in proportion to the pulse width of a signal FPW received from the controller 12. In this way, the fuel injector 66 provides what is known as direct injection of fuel into the combustion chamber 30. The fuel injector 66 may be mounted, for example, in the side of the combustion chamber or in the top of the combustion chamber. The fuel may be delivered to the fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail.

[0016] In select operating modes, an ignition system 88 may provide an ignition spark to the combustion chamber 30 via a spark plug 92 in response to a spark advance (SA) signal from the controller 12. Although spark ignition components are shown, in some embodiments, the combustion chamber 30 or one or more other combustion chambers of the engine 10 may be operated in a compression ignition mode with or without an ignition spark. In light of the present embodiment, the combustion chamber may include additional components and may utilize these components with novel techniques relative to the described embodiment, according to the descriptions of the subsequent figures.

[0017] The intake conduit 42 or intake manifold 44 may include a throttle valve 62 having a throttle plate 64. In this particular example, the position of the throttle plate 64, or a throttle opening, may be varied by the controller 12 via a signal provided to an electric motor or actuator included in the throttle valve 62, a configuration commonly referred to as electronic throttle control (ETC). In this manner, the throttle valve 62 may be operated to vary the intake air provided to the combustion chamber 30, among other engine cylinders. The position of the throttle plate 64 may be provided to the controller 12 by a throttle valve position signal TP. The intake conduit 42 may include a mass air flow sensor 120 and an intake manifold pressure sensor 122 to provide respective MAF and MAP signals to the controller 12.

[0018] Further, an exhaust gas recirculation (EGR) system may direct a desired portion of exhaust gas from the exhaust conduit 48 to the intake manifold 44. In this example, the high-pressure (HP) EGR conduit 140 is illustrated. The amount of EGR delivered to the intake manifold 44 may be varied by the controller 12 via the HP EGR valve 142. Further, an EGR sensor 144 may be disposed in the HP EGR conduit 140 and may provide an indication of one or more of pressure, temperature, and exhaust gas concentration. Alternatively, the EGR flow may be controlled by a calculated value based on signals from the MAF (upstream), MAP (intake manifold), MAT (manifold gas temperature), and the crank speed sensor. Further, the EGR flow may be controlled based on an oxygen sensor and / or an intake manifold oxygen sensor.Under some conditions, the EGR system may be used to regulate the temperature of the air and fuel mixture within the combustion chamber and / or the temperature near a gasoline particulate filter (not shown). During . Fig. 1 shows a high-pressure EGR system, a low-pressure EGR system may be used additionally or alternatively. In a low-pressure EGR system, the EGR may be routed from a position downstream of a turbine of a turbocharger to a position upstream of a compressor of the turbocharger, as in Fig. 1 shown.

[0019] As such, the engine 10 may further include a compression device, such as a turbocharger or a supercharger, including at least one compressor 162 disposed along the intake manifold 44. With a turbocharger, the compressor 162 may be driven at least partially by a turbine 164 disposed along the exhaust conduit 48 (e.g., via a shaft). With a supercharger, the compressor 162 may be driven at least partially by the engine 10 and / or an electric machine and may not necessarily include a turbine. Therefore, the amount of compression provided to one or more cylinders of the engine via a turbocharger or a supercharger may be varied by the controller 12.

[0020] An exhaust gas sensor 126 is shown coupled to the exhaust conduit 48 upstream of the emission control device (ECD) 70. The exhaust gas sensor 126 may be any suitable sensor for providing an indication of an exhaust air / fuel ratio, such as a linear oxygen sensor or UEGO (Universal or Wideband Exhaust Oxygen Sensor), a dual-state oxygen sensor or EGO, a HEGO (Heated EGO), a NOx, HC, or CO sensor. In some embodiments, an exhaust gas sensor 126 may be used in conjunction with an oxygen sensor (not shown) and / or a temperature sensor (not shown).

[0021] The emission control device (ECD) 71 is shown disposed along the exhaust conduit 48 downstream of the exhaust sensor 126. The ECD 71 includes a three-way catalytic converter (TWC) and a gasoline particulate filter (GPF), and may optionally include one or more sensors, such as a pressure sensor or temperature sensor.

[0022] The control 12 is in Fig. 1 as a microcomputer comprising a microprocessor unit 102, input / output ports 104, an electronic storage medium (e.g., computer-readable) for executable programs and calibration values, shown in this particular example as read-only memory 106, a random access memory 108, a retaining memory 110, and a data bus.The controller 12 may receive various signals from sensors coupled to the engine 10, in addition to the signals previously discussed, including an inducted mass air flow (MAF) measurement from the mass air flow sensor 120, an engine coolant temperature (ECT) from the temperature sensor 112 coupled to the cooling sleeve 114, a profile ignition pickup (PIP) signal from a Hall sensor 118 (or other type) coupled to the crankshaft 40, a throttle position (TP) or throttle opening from a throttle position sensor, and an intake manifold absolute pressure (MAP) signal from the pressure sensor 122. From the PIP signal, the controller 12 may generate an engine speed signal RPM (revolutions per minute).The manifold pressure MAP signal from a manifold pressure sensor may be used to provide an indication of vacuum or pressure in the intake manifold. It should be noted that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor may provide an indication of engine torque. Further, this sensor, along with the detected engine speed, may provide an estimate of charge (including air) introduced into the cylinder. In one example, sensor 118, which is also used as an engine speed sensor, may generate a predetermined number of evenly spaced pulses during each revolution of the crankshaft. 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.

[0023] The read-only memory storage medium 106 may be programmed with computer-readable data representing instructions executable by the microprocessor 102 to perform the methods described below, as well as other variations that are expected but not specifically listed. As described above, Fig. 1 only one cylinder of a multi-cylinder engine, and each cylinder may also contain its own set of intake / exhaust valves, fuel injectors, spark plugs, etc.

[0024] Fig. 2 shows a portion of an internal combustion cylinder in an internal combustion engine that includes the modified cylinder of the present embodiment, as well as accompanying components of the in-cylinder thermal energy recovery system 200. In some examples, the modified cylinder of the in-cylinder thermal energy recovery system 200 described herein may be the cylinder 30 of Fig. 1. Thus, the Fig. 2 cylinders 215 shown in the Fig. 1 shown power machine 100.

[0025] As in Fig. 2, the in-cylinder thermal energy recovery system 200 includes a pump 204, a work input 202, a fluid injector 206, an inlet valve 208, an exhaust valve 212, a piping assembly 210, a combustion chamber 214, a cylinder 215, a piston 216, a temperature sensor 217, a heat input 218, a piping network 220, a temperature gradient 222, a turbine 224, a temperature gradient 226, a shaft 228, an engine component 230, a work output 232, a condenser 234, coolant tubes 236, a heat output 238, a temperature gradient 240, and a condensate 242.

[0026] Fig. Figure 2 shows an example of a Rankine cycle modified for use with an internal combustion engine. The Rankine cycle is an idealized thermodynamic cycle of a heat engine (e.g., an internal combustion engine) that converts heat into mechanical work. The heat is supplied externally to a closed loop, typically using water as the working fluid. Fig. 2, the heat is supplied externally through exhaust gases in the combustion chamber 214 of the closed loop consisting of the piping network 220. The efficiency of the Clausius-Rankine cycle is limited by the high heat of evaporation of the working fluid. While the working fluid of Fig. 2 is water, the working fluid can be organic in alternative embodiments. The working fluid, sometimes referred to here as fluid, in a Rankine cycle follows a closed loop via a piping network 220 and is continuously reused. The Rankine cycle can be divided into four processes, which are Fig. 2 are noted as work input 202, heat input 218, work output 232 and heat output 238.

[0027] Out of Fig. 2, it can be seen that the first process of the Rankine cycle begins with the work input 202 and is illustrated as a "W-pump" for illustrative purposes. As an example, a controller 207 (such as the one shown in Fig. 1) drives the pump 204 to drive the working fluid and pump it through the piping network 220 of the in-cylinder thermal energy recovery system 200 and to the fluid injector 206. The condensate 242 of the working fluid is pumped from low to high pressure within the piping network 220. Since the fluid is a liquid in this phase, the pump requires little input energy. The working fluid is pumped downstream from the pump 204 to the fluid injector 206, thus completing the first process (i.e., the work input 202) of the Rankine cycle and beginning the second process (i.e., the heat input 218). In this embodiment, each cylinder 215 (only one is in Fig. 2) of the engine is equipped with at least one fluid injector 206. In addition, each cylinder 215 includes a tube assembly 210, each tube assembly including one or more tubes extending through the combustion chamber 214 of the cylinder 215. For example, each tube assembly 210 may include an array of parallel tubes extending through an interior of the cylinder 215. The fluid injector 206 for each cylinder may be coupled to the tube assembly 210 for the corresponding cylinder 215 (such that working fluid from the fluid injector 206 flows through the interior of the one or more tubes of the tube assembly 210 within the cylinder 215).

[0028] The fluid injector 206 injects working fluid into the tube assembly 210 depending on the temperature of the respective cylinder and the engine operating conditions. For example, the controller 207 may actuate the fluid injector 206 to inject working fluid into the tube assembly 210. The controller 207, via the fluid injector 206, may adjust the timing and amount of fluid injected individually for the cylinder 215 based on the temperature of the cylinder 215 (as determined from an output of the temperature sensor 217 received at the controller 207). For example, for multiple cylinders, where each cylinder has its own tube assembly 210 and fluid injector 206, the controller may adjust the timing and amount of fluid injected into the respective tube assembly 210 based on the temperature of each individual cylinder by individually actuating the respective fluid injector 206.

[0029] The fluid injector 206 can inject fluid into the corresponding tube assembly 210 of the cylinder 215 at the beginning of an exhaust stroke of the cylinder 215. As will be appreciated by those skilled in the art, at the beginning of the exhaust stroke, the combustion chamber 214 is filled with exhaust gas, and the piston 216 is at bottom dead center (BDC). As the exhaust stroke progresses, the exhaust valve 212 opens (while the intake valve 208 remains closed), and the piston 216 rises to its top dead center (TDC). As the exhaust gases are compressed by the piston 216 and directed to the open exhaust valve 212, they come into contact with the outer wall of the one or more tubes of the tube assembly 210. Consequently, the hot exhaust gases heat the fluid flowing through the interior of the one or more tubes of the tube assembly 210 within the combustion chamber 214 of the cylinder 215.The fluid injector 206 may begin injecting fluid into the tube assembly 210 of its corresponding cylinder 215 only after the engine has reached a threshold temperature. Each fluid injector 206 may be controlled by the controller 207, such as the engine controller 12. Fig. 1, can be individually actuated and / or monitored. In summary, the controller supervisor allows different amounts of working fluid to be injected (e.g., via pulse width modulation) into the tube assembly passing through each cylinder 215 and to individually control the injection of working fluid (timing and volumetric amount) to each cylinder 215. By controlling the amount of working fluid injected to each cylinder 215, the controller is able to monitor and control the temperatures of individual cylinders. For example, if cylinder 215 is burning too hot (as reported by temperature sensor 217 to engine controller 207), the controller can responsively send a signal to fluid injector 206 to inject more fluid more frequently until the cylinder temperature drops below a predetermined temperature threshold.After the working fluid is discharged from the fluid injector 206 in the form of an atomized liquid, it flows downstream to the tube assembly 210 and the cylinder 215.

[0030] The tube assembly 210 may be disposed in the head region (i.e., the uppermost region) of the cylinder 215 near the intake valve 208 and / or the exhaust valve 212. The tube assembly 210 is a subsection of the piping network 220 in that the tube assembly 210 is coupled to the piping network 220 on both sides of the cylinder 215. As introduced above, the tube assembly 210 may consist of multiple tubes, with each of the multiple tubes passing through the combustion chamber 214 of the corresponding engine cylinder 215. There may be at least one tube assembly 210 with at least one corresponding fluid injector 206 for each cylinder 215. The tube arrangement 210 can be used for the transport of working fluid and can act as a heat exchanger between the waste heat from exhaust gases in the combustion chamber 214 and the working fluid in the tube arrangement 210.It is understood that the piping network of the tube assembly 210 is separated from the combustion chamber 214 of the cylinder 215 by a wall, so that the working fluid never comes into direct contact with the air-fuel mixture of the cylinder 215. The tube assembly 210 may be uniform in cross-sectional volume and shape, or it may be available in various geometric designs to achieve optimal efficiency in waste heat recovery. For example, the tube assembly 210 may have a larger surface area around the exhaust valve 212 to transfer more waste heat from the exhaust gases to the working fluid. Such a design may allow more heat to be exchanged between the exiting exhaust gases at their peak temperature and the fluid contained within the walls of the tube assembly 210, which in turn allows more work to be generated from the waste heat of the exhaust gases (discussed in more detail below).

[0031] When considering Fig. In summary, from Figure 2, the second process of the Rankine cycle can be described by the heat input 218, illustratively represented as "Q input." During the heat input 218, waste heat from the exhaust gases trapped in the combustion chamber 214 is conductively transferred through the walls of the tube assembly 210 to the working fluid contained therein. The injected, atomized working fluid then undergoes a phase change from a high-pressure liquid to a dry, saturated vapor due to the increase in heat in the surrounding area before exiting downstream of the combustion chamber 214 into the piping network 220.

[0032] After the dry saturated steam reaches the piping network 220, it flows to the upstream turbine 224. On its way through the piping network 220 toward the turbine 224, the steam may experience a temperature decrease due to convection / conduction, represented by the temperature gradient 222. It should be understood that while the steam may lose some of its heat on its way toward the turbine 224, it does not regain a liquid state but maintains a vaporized state capable of producing work.

[0033] As soon as the working fluid arrives at turbine 224 in its dry, saturated vapor state, the third process of the Rankine cycle can begin. The third process, in Fig. 2 as work output 232 and illustrated as "W Turbine," denotes the conversion of recovered heat energy into work output. As the steam of the working fluid expands through the turbine 224, it causes the turbine 224 to rotate, thereby rotating the shaft 228 and generating rotational energy (i.e., torque) that can be used for work (i.e., power). The shaft 228 is coupled to an engine component 230. The engine component 230 represents a component of the engine (such as the engine 100 of Fig. 1) that can utilize rotational energy, where "utilizing rotational energy" means that the engine component 230 can apply the recovered energy to perform and / or supplement an operation. In one embodiment, the engine component 230 can be a crankshaft, an alternator, or a clutch, such as the crankshaft 40 and the clutch 135 of Fig. 1.

[0034] To Fig. 2, as the working fluid expands in its vaporized state through the turbine 224, a decrease in the temperature and pressure of the vapor may occur, and some condensation may occur. The decrease in temperature and pressure may occur in a continuous manner along the temperature gradient 226. After the working fluid successfully reaches the end portion of the turbine 224, it exits the turbine 224 and re-enters the piping network 220. The working fluid then flows through the piping network 220 to exit through an opposite opening in the uppermost portion of the condenser 234. The condenser 234 is the location where the fourth process of the Rankine cycle, designated heat output 238 and illustrated for illustrative purposes as "Q output," takes place.During the heat extraction phase 238 of the Rankine cycle, the working fluid enters the condenser 234 in a wet vapor state, where it is condensed via coolant tubes 236 at a constant pressure to return to its initial state as a saturated liquid (i.e., condensate 242). The temperature decrease of the working fluid may occur along a temperature gradient 240 of the condenser 234. After condensing into a condensate 242, the working fluid may exit the condenser 234 through another portion of the piping network 220, where it flows toward the pump 204 to begin the Rankine cycle again.

[0035] In this way, waste heat from exhaust gases can be used to generate work elsewhere in the vehicle, thereby increasing fuel economy. Furthermore, the temperatures of individual cylinders can be monitored and regulated via a temperature sensor 217, a controller, and a fluid injector 206, thereby increasing component durability.

[0036] The Fig. 1-2 show example layouts with relative positioning of the various components. When elements are shown as being in direct contact with one another or directly coupled, those elements may, at least in one example, be referred to as being in direct contact with one another or directly coupled, respectively. Likewise, elements shown abutting or adjacent to one another may, at least in one example, be abutting or adjacent to one another. For example, components that are in snug contact with one another may be referred to as being in snug contact with one another. In another example, elements that are positioned only a distance apart from one another with no intervening components may, at least in one example, be referred to as such.

[0037] To Fig. 3, a method 300 for setting and operating an in-cylinder thermal energy recovery system, such as that shown in Fig. 2. Instructions for carrying out the method 300 may be provided by a controller (such as the one shown in Fig. 1 shown control 12 and / or the one in Fig. 2) based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the engine system, such as those described above with reference to the Fig. 1-2 described sensors. The control can be engine actuators (e.g. actuators of fluid injectors, such as the one in Fig. 2) of the engine system to adjust engine operation according to the methods described below. Fig. 3 begins at 302, where engine operating conditions are estimated and / or measured. Estimating and / or measuring engine operating conditions may include processing incoming data from sensors inside and / or outside the in-cylinder thermal energy recovery system, determining engine temperature, cylinder temperature, whether vehicle cruise control is enabled, whether the vehicle is accelerating / decelerating, whether the vehicle is experiencing cold-start conditions, etc. For example, engine operating conditions may include engine speed and / or load, ambient temperature, engine temperature, individual cylinder temperatures, etc.

[0038] At 304, the method includes determining whether the conditions for fluid injection are met. As described above with reference to Fig. 2, the working fluid of an in-cylinder thermal energy recovery system is delivered into the piping of an individual engine cylinder via a respective fluid injector in a time- and volumetrically controlled manner. If the temperature of an individual cylinder is not high enough for vaporization of the working fluid through the piping, the controller may determine that the conditions for fluid injection into the piping of that cylinder are not met, so the method continues to 306. For example, at 304, the method may include determining for each cylinder whether the cylinder temperature is greater than a threshold based on a value at which the working fluid can be vaporized and used for energy recovery.

[0039] At 306, the method includes maintaining engine operation and not injecting fluid into the piping of the cylinder. The cylinder continues to operate as usual by undergoing the four stages of combustion known to those skilled in the art without receiving an injection of working fluid into the corresponding piping for the respective cylinder. For example, fuel may be injected into the cylinder via a fuel injector without injecting working fluid into the piping extending through the cylinder via the corresponding fluid injector. The controller may continuously monitor the temperature of the cylinder via a temperature sensor in, on, and / or near the cylinder to determine if the conditions for fluid injection are met.It is understood that each cylinder is individually monitored for temperature and individually assessed by the controller, as described below. For example, one cylinder in an engine may not meet the conditions for fluid injection while the remaining cylinders meet them. In this example, the one cylinder that does not meet the conditions for fluid injection may not receive any working fluid in its corresponding tube assembly, while the remaining cylinders receive adjusted amounts of working fluid in their corresponding tube assemblies. For one cylinder, engine operation continues and fluid injection via a fluid injector is withheld until the conditions for fluid injection are met. Once the conditions for fluid injection are met, the method proceeds to 308.

[0040] At 308, the method includes determining the timing and amount of fluid injection. As previously mentioned, the fluid injectors located at each cylinder are individually monitored and controlled. The fluid injectors deliver atomized droplets of working fluid into the tube assembly of a corresponding cylinder, and the timing and amount of fluid delivered to each cylinder may vary depending on engine operating conditions. Adjusting the timing and amount of injected working fluid may include increasing the amount of injected fluid when a temperature of the engine cylinder increases. For example, a temperature sensor may signal a controller that the temperature of a cylinder is increasing. In response, the controller may signal the respective cylinder's fluid injector to deliver more fluid in a manner proportional to the temperature.The increased amount of working fluid injected into the runner assembly of the corresponding cylinder may dissipate more heat from the cylinder to thereby regulate and / or control the temperature of the cylinder and / or combustion. Adjusting the amount of fluid injected may also include adjusting a pulse width modulation (e.g., a digital signal) sent to the fluid injector. Furthermore, adjusting the timing and amount of injected fluid may include retarding the injection timing from the exhaust stroke of the engine cylinder in response to one or more indications of engine knock and / or cold start conditions. For example, fluid injection may be advanced to occur during a compression stroke of the cylinder (rather than the exhaust stroke) in response to indications of engine knock (e.g., auto-ignition).After the controller determines the amount and timing of working fluid to be injected by each corresponding fluid injector into the respective tube assembly of each cylinder, the method continues to 310.

[0041] At 310, the method includes injecting working fluid into the tube assembly. In response to engine operating conditions, the controller may signal one or more fluid injectors to inject working fluid in the form of an atomized liquid at the beginning of the exhaust stroke of each eligible cylinder (or at the time specified at 308). Due to the fact that the cylinders operate in a staggered manner with a particular firing order, working fluid is injected into all eligible cylinders in a staggered manner and according to the engine's firing order, creating a more or less stable vapor flow for performing work. For example, each cylinder of a six-cylinder engine may be eligible for fluid injection. The cylinders may all operate within the same temperature threshold and may therefore receive the same amount of working fluid injections.At the beginning of each cylinder's exhaust stroke, working fluid may be injected via a fluid injector in an atomized liquid state into a tube assembly above a corresponding cylinder, where the liquid is then vaporized by conductive waste heat. While each cylinder may produce steam at a different time, the staggered manner in which the steam is produced creates a relatively stable stream of steam that flows through the rest of the in-cylinder thermal energy recovery system to perform work. After working fluid is injected into the corresponding tube assembly, the method proceeds to 312.

[0042] At 312, the method includes recovering energy from the working fluid after it has exited the cylinder via the tube assembly. Recovering energy from the working fluid may include directing the working fluid via a piping network to a turbine. Thus, the working fluid in vapor form may drive the turbine, such as turbine 224 of Fig. 2, rotate. The energy from the exhaust gases, once used to vaporize the working fluid into steam, is thus used to drive a turbine and generate rotational energy (i.e., torque) that can be used to perform work. As previously disclosed, the work can take the form of mechanical or electrical energy and can be used to drive or supplement various engine components, such as a crankshaft or clutch. After energy is recovered from the working fluid in vapor form to perform work, the method proceeds to 314.

[0043] At 314, the method includes applying the recovered energy to one or more engine components. For example, the rotational energy recovered from the turbine may be transferred to another mechanical or electrical component in the engine. As one example, the recovered rotational energy may be used to actuate a crankshaft and / or clutch of the engine. In another example, the recovered energy may be used to operate an alternator to generate electricity. The electricity thus generated may be used to offset the electrical load of accessories, which in turn improves fuel economy by reducing the parasitic load imposed on the engine.

[0044] In this way, a vehicle controller can determine during which engine operating conditions it is effective to deliver working fluid to the piping located within a head region of corresponding cylinders. The controller can estimate and / or measure the temperatures of multiple cylinders simultaneously to determine the amount and timing of fluid to inject (or not inject) to each individual cylinder. The controller can then deliver adjusted amounts of working fluid to the corresponding cylinders at different times to create a vapor of the working fluid used to perform work.

[0045] To Fig. 4, a graph is shown depicting the relationship between temperatures of individual engine cylinders and fluid injection quantities. Looking at the x-axis, one can see the title "Time →", which indicates that time progresses from left to right along the x-axis. Looking at the y-axis of the graph, one can see that two cylinders are shown under two different variables. That is, the temperature of cylinder 1 and cylinder 2 and the amount of working fluid injected in each are displayed. The magnitude of these variables present in their respective cylinders is proportional to their position on the y-axis (with a larger y-axis value corresponding to a larger magnitude of the variable, either temperature or working fluid quantity) at a given time defined by the position on the x-axis.To summarize, the temperature of a first cylinder is represented as "Cylinder 1 Temperature." The change in the temperature of that first cylinder over time is represented by line 402. The amount of working fluid injected into the tube assembly of the same first cylinder is represented as "Cylinder 1 Fluid." The change in the amount of working fluid injected into the tube assembly of that first cylinder over time is represented by line 404. The temperature of a second cylinder is represented as "Cylinder 2 Temperature." The change in the temperature of that second cylinder over time is represented by line 406. The amount of working fluid injected into the tube assembly of the same second cylinder is represented as "Cylinder 2 Fluid." The change in the amount of working fluid injected into the tube assembly of that second cylinder over time is represented by line 408.

[0046] To Fig. Returning to Figure 4 and looking at lines 402 and 404, it can be seen that the amount of working fluid injected into the tube assembly of the first cylinder is proportional to the temperature (ie heat) of that same cylinder. Fig. 4, it can be seen that as the temperature of the first cylinder increased upon approaching T1, the amount of working fluid injected into the tube assembly of that cylinder also increased. It should be understood that while the relationship between the amounts of working fluid injected into the tube assembly of cylinders and the temperature of the corresponding cylinder is proportional, an increase in temperature may cause an increase in working fluid injection, but not vice versa. That is, an increase in cylinder temperature may cause the engine controller to actuate a fluid injector to increase the amount of working fluid injected into the respective cylinder. In other words, the controller may increase the amount of injected working fluid to decrease cylinder temperatures and in response to an increase in cylinder temperatures.As previously discussed, the amounts of working fluid to be injected are determined by engine operating conditions. Working fluid may serve to dissipate heat from a cylinder by capturing waste heat from exhaust gases. At T1, the temperature of the first cylinder (i.e., cylinder 1), indicated by line 402, reaches a global maximum. In one example, the global maximum is due to engine operating conditions (such as a steep uphill grade), and a controller signals a fluid injector to deliver an increased amount of working fluid, so the amount of working fluid also reaches a global maximum at T1, indicated by line 404. As line 402 decreases after T1, line 404 also decreases. At reduced temperatures, the first cylinder is unable to vaporize the same amount of working fluid, so the injected amount decreases to match the new cylinder temperatures.

[0047] If you look at the second cylinder Fig.4, it can be seen that the same proportional relationship between cylinder temperature and working fluid injection quantity continues to exist. That is, as line 406 falls as we approach T1, line 408 also falls. As line 406 rises and stabilizes as it moves away from T1, so does line 408. Lines 406 and 408 of the second cylinder do not provide any insight into the relationship between cylinder temperature and working fluid injection quantities that lines 402 and 404 of the first cylinder did not provide; however, by comparing lines 402 and 404 of the first cylinder with lines 406 and 408 of the second cylinder, it can be seen that the injected working fluid quantity of each cylinder is appropriate for that cylinder. For example, more working fluid is injected into cylinder 1 than into cylinder 2 because cylinder 1 has a higher temperature than cylinder 2 at T1.Each cylinder is monitored and / or controlled individually, depending in part on the specific temperatures of that particular cylinder. For example, any temperature change in the first cylinder (i.e., any change in line 402) should not be able to cause a change in lines 406 or 408, since each cylinder is analyzed and treated independently.

[0048] Thus, an in-cylinder thermal energy recovery system can be used to produce increased amounts of work without burning additional fossil fuels, thereby increasing fuel economy. The technical effect of placing the in-cylinder thermal energy recovery system piping in the engine cylinder head is that a greater amount of energy (i.e., more heat) is transferred from the exhaust gases to the working fluid, resulting in the production of a greater amount of work from the same amount of fossil fuel. An additional technical effect of placing the in-cylinder thermal energy recovery system piping in the engine cylinder head is that it allows the controller to regulate the cylinder temperature and / or combustion.

[0049] As one embodiment, a method for an engine includes individually injecting fluid into a plurality of tube assemblies, each tube assembly of the plurality of tube assemblies including one or more tubes passing through a combustion chamber of a corresponding engine cylinder in a region of a head of the engine cylinder based on a temperature of the corresponding engine cylinder, and recovering thermal energy from the injected fluid after it has flowed through each tube assembly. In a first example of the method, the method further includes at least partially actuating one or more components of the engine, such as a crankshaft and a clutch, using the recovered thermal energy. A second example of the method optionally includes the first example and further includes the case where the one or more tubesthe plurality of tubes of each tube arrangement are separated from the combustion chamber of the corresponding cylinder by a wall. A third example of the method optionally includes one or more of the first and second examples, and further includes individually injecting fluid into the plurality of tube arrangements, including individually injecting fluid into each tube arrangement at the beginning of an exhaust stroke of the corresponding engine cylinder. A fourth example of the method optionally includes one or more of the first through third examples, and further includes beginning individually injecting fluid into the plurality of tube arrangements after an engine temperature reaches a threshold temperature.A fifth example of the method optionally includes one or more of the first through fourth examples, and further includes adjusting a timing and amount of individually injected fluid for each tube assembly of each engine cylinder based on the temperature of the engine cylinder. A sixth example of the method optionally includes one or more of the first through fifth examples, and further includes the case where recovering the heat energy includes expanding the steam exiting the plurality of tube assemblies to produce work within a system including a turbine and a compressor.A seventh example of the method optionally includes one or more of the first through sixth examples and further includes where individually injecting fluid comprises actuating, via a controller, individual fluid injectors coupled to each tube assembly upstream of each engine cylinder to inject fluid for a duration, the duration based on a desired amount of fluid injection. An eighth example of the method optionally includes one or more of the first through seventh examples and further includes non-individually injecting fluid into a tube assembly of the plurality of tube assemblies in response to the temperature of the corresponding engine cylinder being below a threshold temperature.

[0050] In another example, a method for an engine includes adjusting a timing and amount of fluid injected into a tubing assembly extending through a combustion chamber of an engine cylinder and located in a head region of the engine cylinder proximate an exhaust valve based on engine operating conditions, recovering thermal energy from the injected fluid after it exits the tubing assembly downstream of the engine cylinder, and actuating an engine component, at least in part, using the recovered thermal energy. In a first example of the method, the method further includes where the engine operating conditions include a temperature of the engine cylinder.A second example of the method optionally includes the first example and further includes the case where adjusting the timing and amount of injected fluid includes increasing the amount of injected fluid as the temperature of the engine cylinder increases. A third example of the method optionally includes one or more of the first and second examples and further includes the case where adjusting the timing and amount of injected fluid includes decreasing the amount of injected fluid as the temperature of the engine cylinder drops. A fourth example of the method optionally includes one or more of the first to third examples and further includes the case where adjusting the timing and amount of injected fluid includes advancing spark timing from the exhaust stroke of the engine cylinder based on an indication of engine knock.A fifth example of the method optionally includes one or more of the first to fourth examples and further includes the case where adjusting the amount of injected fluid includes adjusting a pulse width modulation of an atomizing fluid injector located upstream of the engine cylinder and coupled to the tubing. A sixth example of the method optionally includes one or more of the first to fifth examples and further includes the case where adjusting the timing and amount of fluid injected into the tubing is performed via a controller, the controller actuating a fluid injector coupled to the tubing upstream of the engine cylinder.

[0051] In another embodiment, a system for an engine comprises a plurality of engine cylinders, a plurality of tube assemblies, wherein a tube assembly of the plurality of tube assemblies is mounted to a head portion of each of the plurality of engine cylinders, and each tube assembly includes a plurality of tubes, wherein each tube of the plurality of tubes extends through a combustion chamber of a corresponding one of the plurality of engine cylinders, and wherein the interior of each tube is isolated from the remainder of the combustion chamber, and a plurality of atomizing fluid injectors, wherein at least one fluid injector of the plurality of fluid injectors is coupled to an inlet of each tube assembly, and a heat recovery system is coupled to the plurality of tube assemblies, both upstream and downstream of the plurality of engine cylinders, and a controller including non-transitory instructions stored in memory,to inject fluid individually into each tube assembly of the plurality of tube assemblies via the plurality of fluid injectors based on a temperature of the corresponding engine cylinder, recovering heat energy from the injected fluid after passing through each tube assembly via the heat recovery system, and applying the recovered energy to an additional engine component. In a first example of the method, the method further includes the case where the heat recovery system includes a turbine coupled to a rotatable shaft and a compressor, the rotatable shaft coupled to the additional engine component. A second example of the method optionally includes the first example and further includes the case where each tube assembly includes a larger heat transfer area,which is arranged around an exhaust valve seat of each engine cylinder of the plurality of cylinders. A third example of the method optionally includes one or more of the first and second examples and further includes the case where the plurality of tubes of each tube arrangement includes a plurality of parallel tubes extending through and across a diameter of the corresponding engine cylinder, with a greater concentration of the plurality of parallel tubes positioned around an exhaust valve seat of the corresponding engine cylinder. SUMMARY: Methods and systems are provided for an in-cylinder thermal energy recovery device that utilizes the Rankine cycle to recover energy from exhaust gases that can be used to perform additional work in the vehicle. In one example, a method may include equipping the head region of each cylinder of an engine with a tube arrangement,which includes one or more tubes extending through the combustion chamber of the corresponding cylinder. Each tube arrangement can receive an injection of working fluid based in part on the temperature of the cylinder corresponding to the tube arrangement, which can then be used to recover thermal energy.

Claims

[1] Procedure comprising: Individually injecting fluid into a plurality of tube assemblies (210), each tube assembly (210) of the plurality of tube assemblies (210) including one or more tubes extending through a combustion chamber (214) of a corresponding engine cylinder (215) in a region of a head of the engine cylinder (215), an amount of fluid individually injected into each tube assembly (210) being based on a temperature of the corresponding engine cylinder (215); and recovering heat energy from the injected fluid after it has passed through each tube assembly (210). [2] The method of claim 1, further comprising at least partially actuating one or more of a crankshaft (40) and a clutch (135) of the engine (100) using the recovered thermal energy. [3] The method of claim 1, wherein the one or more tubes of each tube assembly (210) are separated by a wall from the combustion chamber (214) of the corresponding cylinder. [4] The method of claim 1, wherein individually injecting fluid into the plurality of tube assemblies (210) includes individually injecting fluid into each tube assembly (210) at the beginning of an exhaust stroke of the corresponding engine cylinder (215). [5] The method of claim 1, further comprising beginning to individually inject fluid into the plurality of tube assemblies (210) after an engine temperature reaches a threshold temperature. [6] The method of claim 1, further comprising adjusting a timing of the individually injected fluid for each tube assembly (210) of each engine cylinder (215) based on the temperature of the engine cylinder (215). [7] The method of claim 1, wherein recovering the thermal energy includes expanding the steam exiting the plurality of tube assemblies (210) to produce work within a system including a turbine (224) and a compressor. [8] The method of claim 1, wherein individually injecting fluid includes actuating, via a controller (12), individual fluid injectors (206) located upstream of each engine cylinder (215) and coupled to each tube assembly (210) to inject fluid for a duration, the duration being based on a desired amount of fluid injection. [9] The method of claim 1, further comprising non-individually injecting fluid into a tube assembly (210) of the plurality of tube assemblies (210) in response to the temperature of the corresponding engine cylinder (215) being below a threshold temperature. [10] Procedure comprising: Setting a timing and amount of fluid injected into a first tube assembly (210) and a second tube assembly (210) each passing through a combustion chamber (214) of a first engine cylinder (215) and a second engine cylinder (215) and near an exhaust valve (54) in a head region of the first engine cylinder (215) and of the second engine cylinder (215) is arranged based on engine operating conditions of the first engine cylinder (215) and the second engine cylinder (215), respectively; recovering heat energy from the injected fluid after exiting the first tube assembly (210) and the second tube assembly (210), downstream of the first engine cylinder (215) and the second engine cylinder (215); and Operating an engine component (230), at least partially, using the recovered thermal energy. [11] The method of claim 10, wherein the engine operating conditions include a first temperature of the first engine cylinder (215) and a second temperature of the second engine cylinder (215). [12] The method of claim 11, wherein adjusting the timing and amount of injected fluid includes increasing the amount of injected fluid as the first temperature of the first engine cylinder (215) or the second temperature of the second engine cylinder (215) increases. [13] The method of claim 11, wherein adjusting the timing and amount of injected fluid includes decreasing the amount of injected fluid when the first temperature of the first engine cylinder (215) or the second temperature of the second engine cylinder (215) decreases. [14] The method of claim 10, wherein adjusting the timing and amount of injected fluid includes advancing spark timing from the exhaust stroke of the first engine cylinder (215) or the second engine cylinder (215) based on an indication of engine knock. [15] The method of claim 10, wherein adjusting the amount of injected fluid includes adjusting a pulse width modulation of an atomizing fluid injector (206) located upstream of the first engine cylinder (215) and coupled to the first tube assembly (210) or located upstream of the second engine cylinder (215) and coupled to the second tube assembly (210). [16] The method of claim 10, wherein adjusting the timing and amount of fluid injected into the first tube assembly (210) and the second tube assembly (210) is performed via a controller (12), the controller (12) actuating a first fluid injector (206) coupled to the first tube assembly (210) upstream of the first engine cylinder (215) or a second fluid injector (206) coupled to the second tube assembly (210) upstream of the second engine cylinder (215). [17] A system for a prime mover (100) comprising: several engine cylinders (215); a plurality of tube assemblies (210), wherein a tube assembly (210) of the plurality of tube assemblies (210) is mounted to a head portion of each of the plurality of engine cylinders (215), and each tube assembly (210) includes a plurality of tubes, each tube of the plurality of tubes extending through a combustion chamber (214) of a corresponding one of the plurality of engine cylinders (215), and an interior of each tube being insulated from a remainder of the combustion chamber (214); a plurality of atomizing fluid injectors (206), wherein at least one fluid injector (206) of the plurality of fluid injectors (206) is coupled to an inlet of each tube assembly (210); a heat recovery system coupled to the plurality of tube assemblies (210) both upstream and downstream of the plurality of engine cylinders (215); and a controller (12) containing non-volatile instructions stored in a memory to cause: individually injecting fluid via the plurality of fluid injectors (206) into each tube assembly (210) of the plurality of tube assemblies (210) based on the temperature of the corresponding engine cylinder (215); recovering heat energy from the injected fluid after it has passed through each tube assembly (210) via the heat recovery system; and Applying the recovered energy to an additional engine component (230). [18] The system of claim 17, wherein the heat recovery system includes a turbine (224) coupled to a rotatable shaft and a compressor, the rotatable shaft coupled to the additional engine component (230). [19] The system of claim 17, wherein each tube assembly (210) includes a larger heat transfer area disposed around an exhaust valve seat (54) of each engine cylinder (215) of the plurality of cylinders. [20] The system of claim 17, wherein the plurality of tubes of each tube assembly (210) includes a plurality of parallel tubes extending through and across a diameter of the corresponding engine cylinder (215), with a greater concentration of the plurality of parallel tubes positioned around an exhaust valve seat (54) of the corresponding engine cylinder (215).

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