APPROACH FOR AN ALTERNATE PRESSURE OIL INJECTION

Abstract

Method (200) for operating an engine (10) including an oil injector (184) which sprays oil onto a piston (36) of the engine (10), comprising adjusting the oil injection in response to signs of pre-ignition, characterized by stopping the fuel injection into one or more cylinders of the engine (10) in response to signs of pre-ignition.

Description

Background and overview

[0001] Piston cooling nozzles or oil injectors can be implemented in an engine for cooling the cylinders. For example, JP 2005-273572 A discloses a device for controlling the combustion of an internal combustion engine that is capable of suppressing engine knocking and preventing a loss of engine power associated with the suppression of knocking. JP 2008-38757 A describes a piston cooling system for an internal combustion engine that appropriately controls oil injection to a piston depending on the operating state of the internal combustion engine. Furthermore, JP 2010-84619 A discloses a method for predicting and suppressing the occurrence of unusual combustion, such as pre-ignition, in an engine.

[0002] Specifically, each oil injector sprays oil onto the underside of a corresponding piston to provide a cooling effect on the piston. Furthermore, the oil spreads from the underside of the piston to the surrounding walls of a corresponding engine cylinder as the piston moves up and down within the engine cylinder to provide a cooling effect in the combustion chamber. In one example, the oil injector is activated when the oil pressure in the engine is sufficient to overcome the pressure level of a check valve in the qualifying group. As long as the oil pressure is greater than the pressure level of the check valve, the injector sprays oil onto the piston.

[0003] However, the inventors identified several potential problems with such a configuration. For example, since the operation of the oil injector is based solely on the pressure setting of the check valve in the oil injector assembly, the amount of oil sprayed by the oil injector cannot be adjusted to different operating conditions. In one example, if the check valve pressure level is too high, the oil injector will operate less frequently, reducing cooling, leading to increased engine knock and thus poor drivability, or pre-ignition and thus engine damage.

[0004] In another example, if the check valve pressure level is too low, the oil injector operates more frequently, supplying the engine cylinder with additional oil beyond what is adequate for oil cooling. This additional oil increases oil consumption and forms more oil deposits in the combustion chamber. These oil deposits have an insulating effect, slowing heat dissipation from the combustion chamber and contributing to engine knock and / or pre-ignition.

[0005] In one example, a solution to the aforementioned problems can be achieved by a method for operating an engine with an oil injector that sprays oil onto the engine's piston and adjusts the oil injection in response to signs of pre-ignition. By adjusting the oil injection, appropriate cooling effects can be achieved without supplying additional oil, which would increase oil deposits in the engine. In this way, the risk of pre-ignition can be reduced.

[0006] Furthermore, this approach allows for more precise control of oil injection than the purely binary operation of previous designs. As such, oil injection can be adjusted in various ways to accommodate different operating conditions. For example, oil injection can be adjusted by a first amount in response to signs of pre-ignition and by a second amount, different from the first amount, in response to signs of engine knock.

[0007] It is obvious that the foregoing overview serves the purpose of introducing a selection of terms in a simplified form, which are further explained in the detailed description below. It is not intended to identify essential or principal features of the claimed subject matter, the scope of which is defined by the claims following the detailed description.

[0008] Furthermore, the claimed subject matter is not limited to embodiments that remedy the disadvantages noted above or elsewhere in this disclosure. Brief description of the drawings

[0009] The subject matter of the present disclosure can be better understood by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which: Fig. 1 shows an embodiment of an engine system of the present disclosure. Fig. 2 shows an embodiment of a method for controlling oil injection to meet different operating conditions. Fig. 3 shows an embodiment of a method for controlling oil injection based on engine cylinder temperature to accommodate different operating conditions. Fig. 4 shows an embodiment of a method for controlling cylinder-specific oil injection according to cylinder-specific operating conditions. Detailed description

[0010] The subject matter of the present disclosure will now be described by way of example and with reference to specific embodiments illustrated in the drawing. It is noted that the figures accompanying this disclosure depict schematic representations and are identified as such. In the schematic representations, views of the illustrated embodiments are generally not to scale; aspect ratios, feature sizes, and the number of features have been intentionally distorted to make selected features or relationships more easily visible.

[0011] Fig. 1 shows a schematic representation of one cylinder of a multi-cylinder engine 10 that may be included in the propulsion system of a motor vehicle. The engine 10 may be controlled at least in part 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 combustion chamber (i.e., cylinder) 30 of the engine 10 may include combustion chamber walls 32 with a piston 36 positioned therein. The piston 36 may be connected to the crankshaft 40 such that reciprocating motion of the piston is translated into rotary motion of the crankshaft. The crankshaft 40 may be connected to at least one drive wheel of a vehicle via an intermediate gear.Furthermore, a starter can be coupled to the crankshaft 40 via a flywheel to enable a starting process of the engine 10.

[0012] Combustion chamber 30 may receive intake air from intake manifold 44 via intake passage 42 and expel combustion exhaust gases via exhaust passage 48. Intake manifold 44 and exhaust passage 48 may selectively communicate with combustion chamber 30 via the respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may have two or more intake valves and / or two or more exhaust valves.

[0013] In this example, intake valve 52 and exhaust valve 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or valve lift (VVL) systems actuated by a controller 12 to vary valve actuation. For example, valve actuation may be varied as part of spark advance or engine knock prevention actions. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In other embodiments, intake valve 52 and / or exhaust valve 54 may be controlled by electrical valve actuation.For example, cylinder 30 may alternatively include an electrically actuated intake valve and a cam-actuated exhaust valve with CPS and / or VCT systems.

[0014] The engine 10 may further include a compression device such as a turbocharger or supercharger having at least one compressor 162 attached to the intake manifold 44. With a turbocharger, the compressor 162 may be driven at least partially by a turbine 164 disposed at the exhaust port 48 (e.g., via a shaft). With a supercharger, the compressor 162 may be driven at least partially by the engine and / or an electric machine and may not include a turbine. Thus, the degree of compression delivered to the one or more cylinders of an engine via turbochargers or superchargers may be varied by the controller 12. A boost pressure sensor 123 may be disposed downstream of the compressor in the intake manifold 44 and sends a boost pressure signal to the controller 12.

[0015] The fuel injector 66 is shown coupled directly to the combustion chamber 30 for injecting fuel directly into the chamber proportional to the pulse width of the FPW signal received from the controller 12 via the electronic driver 68. Thus, the fuel injector 66 delivers fuel to the combustion chamber 30 in a manner known as direct injection. The fuel injector may, for example, be located in the side of the combustion chamber or on top of the combustion chamber. Fuel is delivered to the fuel injector 66 from a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some embodiments, the combustion chamber 33 may alternatively or additionally include a fuel injector disposed in the intake passage 44, providing a configuration of fuel injection into the intake passage upstream of the combustion chamber 30 known as port injection.The fuel injector 66 can be controlled to vary fuel injection to the various cylinders according to operating conditions. According to the invention, as part of the pre-ignition prevention measures, the controller 12 can order a cessation of fuel injection to one or more cylinders to allow the combustion chamber 30 to cool. Furthermore, the intake valve 52 and / or the exhaust valve 53 can be opened in conjunction with the cessation of fuel injection to provide intake air for additional cooling.

[0016] The intake passage 42 may include a throttle valve 62 with a throttle plate 64. In this particular example, the position of the throttle plate 64 may be changed by the controller 12 via a signal sent to an electric motor or actuator associated with the throttle valve 62, a configuration commonly referred to as electronic throttle control (ETC). In this manner, the throttle valve 62 may be actuated to vary the intake air directed into the combustion chamber 30 among the other engine cylinders. The position of the throttle plate 64 may be communicated to the controller 12 by the throttle position signal TP. The intake passage 42 may include a mass air flow sensor 120 and an intake manifold pressure sensor 122 for providing the respective MAF and MAP signals to the controller 12.

[0017] The ignition system 88 may, during select operating modes, provide an ignition spark to the combustion chamber 30 via the spark plug 92 in response to the spark advance signal SA from the controller 12. The controller 12 may vary the SA signal depending on operating conditions. For example, the controller may delay the SA signal to delay the spark in response to indications of engine knock as part of engine knock prevention measures. Although spark ignition components are illustrated, 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.

[0018] A variable flow oil pump 180 may be coupled to the crankshaft 40, which provides the rotational force to actuate the variable flow oil pump 180. In one example, the variable flow oil pump 180 includes a plurality of internal, eccentrically mounted rotors (not shown). At least one of the internal rotors may be actuated by the controller 12 to change the position of that rotor relative to one or more other rotors to control the discharge flow rate of the variable flow oil pump 180 and, in turn, the oil pressure. For example, the electronically controlled rotor may be coupled to a rack and pinion assembly that is adjusted by the controller 12 to change the rotor position. The variable flow oil pump 180 may selectively deliver oil to different areas and / or components of the engine 10 for cooling and lubrication.The flow rate or oil pressure of the variable-flow oil pump 180 can be adjusted by the controller 12 to accommodate different operating conditions and provide different levels of cooling and / or lubrication. Furthermore, the oil pressure delivered by the variable-flow oil pump 180 can be adjusted to reduce oil consumption and / or reduce energy consumption by the variable-flow oil pump 180.

[0019] It will be appreciated that any suitable variable-flow oil pump configuration may be implemented to vary the oil pressure and / or oil flow rate. In some embodiments, the variable-flow oil pump 180 may be coupled to a camshaft instead of the crankshaft 40, or may be driven by another power source, such as an engine.

[0020] The oil injector 184 may be disposed downstream of a discharge end of the variable flow oil pump 180 to selectively receive oil from the variable flow oil pump 180. In some embodiments, the oil injector 184 may be incorporated into the combustion chamber walls 32 of the engine cylinder and receive oil from oil passages formed in the walls. The oil injector 184 may be operable to spray oil from the variable flow oil pump 180 onto the underside of the piston 36. The oil injected by the oil injector 184 has a cooling effect on the piston 36. In addition, the reciprocating motion of the piston 36 draws oil upward into the combustion chamber 30, thereby cooling the walls of the combustion chamber 30.

[0021] A valve 182 may be disposed between the discharge end of the variable-flow oil pump 180 and the oil injector to control oil flow to the oil injector 184. In some embodiments, the valve 182 may be a check valve set to open at a predetermined pressure or temperature level when operation of the oil injector 184 for cooling is desired. In some embodiments, the check valve may be integrated into the oil injector 184 assembly.

[0022] In some embodiments, valve 182 may be electronically operable and controlled by controller 12. Valve 182 may be operable to deliver oil to oil injector 184 in response to signs of pre-ignition or engine knock in combustion chamber 30. Similarly, valve 182 may be operable to stop oil injection if, for example, a cylinder temperature drops below a threshold at which cooling effects are less desirable than reduced oil consumption and / or oil deposits in the combustion chamber.

[0023] The vibration sensor (e.g., accelerometer) 186 is shown disposed in the wall 32 of the combustion chamber. The vibration sensor 186 provides indications of vibration (VIB) in the combustion chamber to the controller 12. The vibration sensor 186 may be used to determine indications of pre-ignition or engine knock in the combustion chamber 30. For example, indications of pre-ignition may be determined from larger vibrations in the engine cycle before spark, and indications of engine knock may be determined from smaller vibrations later in the engine cycle after ignition. Although a vibration sensor is provided as an example for determining indications of pre-ignition and / or engine knock, it should be understood that any sensor suitable for detecting indications of pre-ignition or engine knock may be used.

[0024] The controller 12 may regulate the operation of the variable flow oil pump 180 in response to receiving an indication of pre-ignition and / or engine knock from the vibration sensor 186. For example, the controller may regulate the oil delivery of the variable flow oil pump 180 to regulate oil injection by the oil injector 184 onto the piston 36. More specifically, the oil injection may be adjusted to a first amount in response to indications of pre-ignition and to a second amount, different from the first, in response to indications of engine knock. For example, the oil injection may be increased to a higher flow rate or higher oil pressure in response to indications of pre-ignition to provide more cooling, as pre-ignition may occur at higher temperatures. In this way, a greater cooling effect may be achieved to reduce the risk of further pre-ignition in the combustion chamber 30.

[0025] Exhaust gas sensor 126 is shown coupled to exhaust passage 48, which is located upstream of emission control system 70. Sensor 126 may be any sensor suitable for indicating the air / fuel ratio of the exhaust gas, for example, a linear oxygen sensor or UEGO (Universal or Wide-Range Exhaust Gas Oxygen), a bistable oxygen sensor or EGO, a HEGO (Heated EGO), NOx, HC, or CO sensor. Emission control system 70 is disposed along exhaust passage 48 and is shown downstream of exhaust gas sensor 126. System 70 may be a three-way catalyst (TWC), a NOx trap, various other emission control devices, or combinations thereof. In some embodiments, emission control system 70 is periodically reset during operation of engine 10 by operating at least one cylinder of the engine within a particular air / fuel ratio.

[0026] The control 12 is in Fig. 1 as a microcomputer and includes a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, illustrated in this particular example as a read-only memory chip 106, RAM 108, a retained memory (KAM) 110, and a data bus. The controller 12, in addition to the signals previously discussed, may receive various signals from sensors coupled to the engine 10, including the inducted mass air flow (MAF) measurement from the mass air flow sensor 120; a profile ignition pickup (PIP) signal from the Hall effect sensor 118 (or other sensor type) mounted on the crankshaft 40; throttle position (TP) from a throttle position sensor; and an absolute manifold pressure (MAP) signal from sensor 122. An engine speed signal in rpm can be generated by the controller 12 from the PIP signal.The manifold pressure MAP signal from a manifold pressure sensor can indicate vacuum or pressure in the intake manifold. Note that various combinations of the aforementioned sensors can be used, for example, a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor can indicate engine torque. Furthermore, this sensor, along with the detected engine speed, can provide an estimate of the charge (including air) in the cylinder. In one example, sensor 118, which is also used as an engine speed sensor, can generate a predetermined number of evenly spaced pulses during each revolution of the crankshaft.

[0027] Furthermore, the controller 12 may receive signals that may indicate pre-ignition or engine knock in the combustion chamber 30. For example, the engine coolant temperature (ECT) may be sent to the controller 12 from the temperature sensor 112 connected to the cooling sleeve 114 and may indicate whether the combustion chamber temperature is within the range where pre-ignition may occur. The controller 12 may adjust oil injection in response to signs of pre-ignition, including an engine temperature above a threshold. Additionally or alternatively, the vibration sensor 186 may send a signal indicative of pre-ignition when it detects vibrations consistent with the vibration profile of pre-ignition (e.g., larger amplitude, earlier in the engine cycle, etc.). The controller 12 may receive an oil pressure indication from the oil pressure sensor 188 located downstream of the discharge end of the variable flow oil pump 180.The oil pressure indicator can be used by the controller 12 to regulate the oil pressure by varying the flow rate from the oil pump.

[0028] The storage medium read-only memory 106 is programmable with computer-readable data representing instructions executable by the processor 102 for performing the methods described below, as well as other contemplated variations not specifically listed herein.

[0029] As stated above, Fig. 1 only one cylinder of a multi-cylinder engine, where each cylinder can equally have its own set of intake / exhaust valves, fuel injection pump, spark plug, oil injector, etc.

[0030] The configurations illustrated above allow for several methods for varying the pressure of the oil injected by the oil injector. Accordingly, some of these methods will now be described by way of example, with continued reference to the configurations mentioned. However, it will be appreciated that these methods and others fully within the scope of the present disclosure may also be enabled via other configurations.

[0031] It is expected that the control and estimation routines and methods disclosed herein can be used with various system configurations. These routines may represent one or more different processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, the disclosed process steps (operations, functions, and / or actions) may represent code to be programmed into the computer-readable storage medium in an electronic control system.

[0032] It will be appreciated that some of the process steps described and / or illustrated herein may be omitted in some embodiments without departing from the scope of this disclosure. Likewise, the specified sequence of process steps may not always be required to achieve the intended results, but they are included for convenience of illustration and description. One or more of the illustrated actions, functions, or operations may be performed repeatedly depending on the strategy employed.

[0033] Fig. 2 shows an embodiment of a method 200 for controlling oil injection to accommodate different operating conditions. In one example, the method 200 may be implemented by the Fig. 1. At step 202, the method may include determining operating conditions. Determining the operating conditions may include receiving information from various components of the engine 10. For example, the controller 12 may receive operating condition information from the variable flow oil pump 180, such as a flow rate or oil pressure setting, operating condition information from various valves, including valve 182, etc. Further, determining the operating conditions may include monitoring various parameters of the engine 10 or receiving signals from various sensors attached to the engine 10. The monitored parameters may include, for example, engine / cylinder temperature, cylinder pressure, engine oil temperature, engine oil pressure, engine / cylinder vibration, etc.

[0034] At step 204, the method may include determining whether there are indications of pre-ignition or whether pre-ignition has occurred. Pre-ignition may occur in an engine cylinder under certain operating conditions. Thus, in some embodiments, these indications of pre-ignition may include determining whether operating parameters corresponding to these operating conditions have been received from various sensors. As an example, pre-ignition may occur within a certain engine temperature range. Accordingly, determining the presence of pre-ignition may include determining whether the engine temperature is greater than the temperature threshold or has entered a temperature range where pre-ignition occurs. As another example, determining the presence of pre-ignition may include receiving a signal indicating engine / cylinder vibrations greater than the threshold.Engine / cylinder vibrations may still indicate pre-ignition if they occur before the ignition spark in the engine cycle. If it is determined that pre-ignition is present, the method proceeds to step 206. Otherwise, the method proceeds to step 212.

[0035] At step 206, the method may include adjusting oil injection by the oil injector. The oil injection may be varied by a first amount to achieve sufficient cooling to prevent pre-ignition. In some cases, oil injection may be controlled by adjusting oil pressure. In some cases, oil injection may be controlled by adjusting flow rate. In some embodiments, controlling oil injection by the oil injector 184 may include adjusting a variable flow oil pump 180 to control oil pressure or oil flow rate to the oil injector. More specifically, the delivery flow rate of the variable flow oil pump may be increased to increase oil pressure to the oil injector and thus the amount of oil sprayed onto the piston by the oil injector.Optionally or additionally, the oil injection control may include adjusting the state of a valve between the oil injector 184 and the variable flow oil pump 180 to control the oil injection.

[0036] It is obvious that controlling the injection pressure of the oil injected by the oil injector may involve increasing the injection pressure from a first pressure level to a second pressure level higher than the first pressure level. Conditions may occur where the oil injector injects a suitable amount of oil to cool the piston / cylinder without supplying additional oil to reduce the possibility of oil deposits forming in the combustion chamber. Afterward, operating conditions may change, and signs of pre-ignition may appear, for example, when the engine speed increases, which correspondingly leads to an increase in cylinder temperature.In response to the increase in cylinder temperature, the injection pressure or flow rate of the oil injected by the oil injector is increased from a first pressure level to a second pressure level in order to provide a better cooling effect on the piston / cylinder and thus reduce the risk of pre-ignition in the cylinder.

[0037] At step 208, the method may include performing pre-ignition prevention measures. As one example, pre-ignition prevention measures may include setting a rich air / fuel ratio so that additional fluid provides more cylinder cooling. According to the invention, pre-ignition prevention measures may include adjusting fuel injection to stop combustion. Accordingly, valves may be opened to provide intake air for cylinder cooling. Furthermore, pre-ignition prevention measures may include any suitable operations to cool the combustion chamber with the goal of reducing the risk of pre-ignition.

[0038] At step 210, the method may include determining whether pre-ignition conditions are present. If it is determined that pre-ignition indications are present, the method returns to step 206. Otherwise, the method proceeds to step 212.

[0039] At step 212, the method may include determining whether there are indications of engine knock. As one example, the indications of engine knock may include a vibration greater than the threshold. The threshold for engine knock vibrations may be less than the threshold for pre-ignition vibrations. Furthermore, engine knock vibrations may occur after the spark later in the engine cycle, while pre-ignition vibrations may occur before the spark. If it is determined that there are indications of engine knock, the method proceeds to step 214. Otherwise, the method returns to other operations.

[0040] At step 214, the method may include adjusting oil injection by the oil injector. The oil injection may be varied by a second amount that differs from the first amount (for spark advance) to achieve sufficient cooling to prevent engine knock. In some cases, oil injection may be controlled by adjusting oil pressure. In some cases, oil injection may be controlled by adjusting flow rate. In some embodiments, controlling oil injection by the oil injector 184 may include adjusting a variable flow oil pump 180 to control oil pressure or oil flow rate to the oil injector. Optionally or additionally, controlling oil injection may include adjusting the state of a valve between the oil injector 184 and the variable flow oil pump 180 to control oil injection.In some cases, oil injection may involve adjusting oil injection by actuating valve 184. In some cases, oil injection may be stopped in favor of other engine knock prevention measures.

[0041] At step 216, the method may include performing engine knock prevention measures. As an example, an engine knock prevention measure may include retarding the ignition spark to more completely combust the fuel and / or exhaust gas in the combustion chamber.

[0042] At step 218, the method may include determining whether there are any indications of engine knock. If it is determined that there are any indications of engine knock, the method returns to step 214. Otherwise, the method returns to other operations.

[0043] By adjusting oil injection based on indicators of pre-ignition and / or engine knock, an amount of oil can be provided to adequately cool the piston / cylinder, but not additional or excess oil, which would create deposits in the combustion chamber. This can reduce the risk of pre-ignition in the combustion chamber. Furthermore, no additional parts are required for additional injection pressure control if oil injection is controlled simply by changing the delivery flow rate of the variable-flow oil pump. This can reduce manufacturing and / or maintenance costs.

[0044] Fig. 3 shows an embodiment of a method 300 for controlling oil injection based on an engine parameter, in particular the engine cylinder temperature, to accommodate different operating conditions. In one example, the method 300 can be implemented by the Fig. 1 may be executed. At step 302, the method may include determining operating conditions. At step 304, the method may include determining whether the cylinder temperature is greater than a first threshold. In one example, this determination is made based on a temperature signal received from temperature sensor 112. The first threshold may be a predetermined temperature at which pre-ignition may occur. In some embodiments, the first threshold defines a lower limit of an upper temperature range at which pre-ignition is likely or very likely to occur. In some embodiments, the first threshold may be a temperature corresponding to a pressure greater than the actuation pressure of the check valve of the oil injector assembly. In other words, the oil injector may already be injecting oil and the oil pressure may be elevated, rather than transitioning from no oil injection (e.g., off) to oil injection (e.g.,If it is determined that the cylinder temperature is higher than a first threshold, the method proceeds to step 306. Otherwise, the method proceeds to step 308.

[0045] At step 306, the method may include adjusting oil injection to a first amount. In some cases, adjusting oil injection to a first amount may include controlling an oil pressure. In some cases, adjusting oil injection to a first amount may include controlling a flow rate of the oil injection. Adjusting oil injection to a first amount may include increasing the delivery rate or delivery pressure of the variable flow oil pump 180. Because there are operating conditions where pre-ignition is likely or highly likely (e.g., the upper temperature range), in some embodiments, the injection pressure may increase to a higher or the highest value to achieve a greater or the greatest suitable cooling effect.However, it is probably obvious that the injection pressure can be increased without achieving the highest injection pressure suitable for adequate piston / cylinder cooling under such conditions. Furthermore, the injection pressure can be controlled within the upper temperature range for adequate cooling (e.g., increasing the injection pressure as the cylinder temperature increases).

[0046] At step 308, the method may include determining whether the cylinder temperature is below the first threshold and above a second threshold that is lower than the first threshold. The second threshold may be a predetermined temperature at which pre-ignition may occur. In some cases, the second threshold may be a temperature at which pre-ignition is less likely to occur than at the first temperature threshold. Further, in some embodiments, the second threshold defines a lower limit and the first threshold defines an upper limit of a mid-range temperature range in which adequate cooling may be achieved by injecting a smaller amount of oil to the piston / cylinder compared to the upper temperature range above the first threshold. If the cylinder temperature is determined to be below the first threshold and above the second threshold, the method proceeds to step 310.Otherwise, the process goes to step 312.

[0047] At step 310, the method may include adjusting oil injection by the oil injector to a second amount that is less than the first amount. Adjusting oil injection to the second amount may include regulating the delivery flow rate or oil pressure of the variable flow oil pump 180. Further, adjusting oil injection to the second amount may include regulating the state of the valve 182. Because the cylinder temperature is lower, less oil may be used, yet sufficient cooling may still be achieved to reduce the likelihood of pre-ignition in the combustion chamber. As such, the injection pressure or flow rate, and thus the amount of oil sprayed onto the piston / cylinder by the oil injector, may be reduced to reduce oil consumption and reduce the likelihood of oil deposits in the combustion chamber.

[0048] At step 312, the method may include determining whether the cylinder temperature is lower than the second threshold. In some embodiments, the second threshold defines an upper limit of a lower temperature range in which pre-ignition does not occur because the combustion chamber is not hot enough. If the cylinder temperature is determined to be lower than the second threshold, the method proceeds to step 314. Otherwise, the method returns to other operations.

[0049] At step 314, the method may include stopping oil injection by the oil injector. Stopping oil injection may include actuating a valve. In some embodiments, the valve may be a check valve disposed within the oil injector assembly. In some embodiments, the valve may be an upstream valve located between the variable flow oil pump 180 and the oil injector 184. In some embodiments, the valve may be a check valve. In some embodiments, the valve may be an electronic solenoid valve.

[0050] The above method can be carried out to fine-tune oil injection for different operating conditions. In particular, if the cylinder temperature is in a first or upper temperature range in which pre-ignition is likely to occur, the injection pressure can be increased or set to a first, larger amount for more cooling. If the cylinder temperature still remains in a second temperature range that is lower than the first temperature range, so that less oil can be used to provide adequate cooling, the injection pressure can be lowered or set to a second amount that is less than the first amount. The second oil injection amount provides adequate cooling and reduces oil consumption as well as the likelihood of oil deposits in the combustion chamber.Oil consumption is further reduced by stopping oil injection when the cylinder temperature enters a third or lower temperature range where pre-ignition does not occur.

[0051] Fig. 4 shows an embodiment of a method 400 for controlling cylinder-specific oil injection according to cylinder-specific operating conditions. In one example, the method 400 can be implemented by the Fig.1 may be executed. At step 402, the method may include determining operating conditions. At step 404, the method may include determining whether cylinder-specific indicators of pre-ignition are present. In one example, this determination is made based on a signal received from various temperature sensors coupled to each cylinder. In another example, the determination is made based on cylinder-specific vibration signals sent from the vibration sensor. If a cylinder-specific indicator of pre-ignition is determined to be present, the method proceeds to step 406. Otherwise, the method proceeds to step 412.

[0052] At step 406, the method may include controlling oil injection for the indicated cylinder exhibiting pre-ignition signs. In some cases, oil injection may be controlled for some or all of the cylinders for which pre-ignition signs are indicated.

[0053] At step 408, the method may include performing pre-ignition prevention actions for the indicated cylinder exhibiting pre-ignition signs. In some cases, pre-ignition prevention action may be performed for some or all of the cylinders indicated to exhibit pre-ignition signs.

[0054] At step 410, the method may include determining whether cylinder-specific pre-ignition indicators are present. If a cylinder-specific pre-ignition indicator is determined to be present, the method returns to step 406. Otherwise, the method proceeds to step 412.

[0055] At step 412, the method may include maintaining oil injection for the oil injectors of the cylinders for which no indications of pre-ignition are indicated. Maintaining oil injection may not include regulating oil injection for those cylinders for which no indications of pre-ignition are indicated. In some cases, maintaining oil injection may include maintaining oil injection at a set amount, flow rate, and / or oil pressure. In some cases, maintaining oil injection may include keeping one or more oil injectors off.

[0056] At step 414, the method may include increasing or decreasing the air / fuel ratio of cylinders for which no signs of pre-ignition are indicated. In some cases, the air / fuel ratio may be left at the same level. In some cases, the air / fuel ratio may be set lean to compensate for a rich air / fuel ratio setting in the indicated cylinder as part of pre-ignition prevention measures.

[0057] By implementing oil injection control and pre-ignition prevention on a cylinder and / or oil injector basis, the measure can be fine-tuned at an individual level to accommodate the operating conditions prevailing in each cylinder. Furthermore, it is clear that in some embodiments, the aforementioned method may need to be adapted to implement cylinder-specific engine knock prevention measures.

[0058] 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 particular routines described herein may represent one or more of any number of different processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various of the illustrated actions, operations, or functions may be performed in the illustrated sequence, in parallel, or may sometimes be omitted. Likewise, the order of processing is not required to achieve the features and benefits of the example embodiments described herein; it is chosen here for convenience of illustration and description. One or more of the illustrated actions or functions may be performed repeatedly depending on the strategy employed.Furthermore, the described actions may graphically represent a code that is to be programmed into a computer-readable storage medium in the engine control system.

[0059] It is understood that the configurations and routines disclosed herein are exemplary and not limiting, as numerous variations are possible. For example, the disclosed technology may be applied to V-6, I-4, I-6, V-12, horizontally opposed four-stroke engines, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0060] Finally, it is to be understood that the subject matter, systems, and methods described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered limiting, as numerous variations are contemplated. Accordingly, the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and methods disclosed herein, as well as any equivalents thereof.

Claims

[1] A method (200) for operating an engine (10) including an oil injector (184) that sprays oil onto a piston (36) of the engine (10), comprising adjusting the oil injection in response to indications of pre-ignition, characterized by Stopping fuel injection into one or more cylinders of the engine (10) in response to indications of pre-ignition. [2] Method (200) according to claim 1, characterized by that adjusting the oil injection includes regulating a flow rate of the oil injection. [3] Method (200) according to claim 1, characterized by that adjusting the oil injection includes regulating an injection pressure of the oil injection. [4] Method (200) according to claim 1, characterized by in that the engine (10) has a variable flow oil pump (180), and in that adjusting the oil injection comprises regulating the operation of the variable flow oil pump (180) to regulate the oil injection. [5] Method (200) according to claim 1, characterized by that the indication of pre-ignition includes engine vibration exceeding a threshold. [6] Method (200) according to claim 1, characterized by that the indication of pre-ignition includes an engine temperature exceeding a limit. [7] The method (200) of claim 1, further comprising: adjusting oil injection by the oil injector (184) in response to indications of engine knock. [8] Method (200) according to claim 7, characterized by that the oil injection is adjusted by a first amount in response to signs of pre-ignition and by a second amount, different from the first amount, in response to signs of engine knock.

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