EP3126655B1

EP3126655B1 - Fast engine synchronization for restart management

Info

Publication number: EP3126655B1
Application number: EP15773649.7A
Authority: EP
Inventors: Vivek A. Sujan; C. Larry Bruner; Udaya UPPALA
Original assignee: Cummins Inc
Current assignee: Cummins Inc
Priority date: 2014-03-31
Filing date: 2015-03-30
Publication date: 2020-10-28
Anticipated expiration: 2035-03-30
Also published as: CN106164452B; CN106164452A; EP3126655A4; WO2015153448A1; EP3126655A1

Description

TECHNICAL FIELD

The present disclosure relates to restarting an internal combustion engine. More particularly, the present disclosure relates to a system and method of memorizing an engine stop location to enable a quick restart of the engine.

BACKGROUND

Internal combustion engines generate mechanical energy from a chemical energy input (e.g., fuel such as gasoline, diesel, natural gas, etc.). As fuel costs have increased, consumers have demanded low fuel consumption engines. As a result, hybrid and electric vehicles have become increasingly popular due to their relatively low fuel consumption. Often, however, hybrid and electric vehicles are not considered by consumers as having the power necessary for various applications (e.g., semi-tractor trailer applications). Accordingly, traditional fuel-powered engines remain prevalent. However, combustion characteristics have been and are being studied to determine a minimum amount of fuel necessary for combustion to occur in various types of engines.
Regardless of the engine type, for combustion to occur, the engine must be operating at a sufficient speed (revolutions-per-minute, "RPM"). For a fuel-injected engine, the fuel must also be injected when the piston is at a location that allows for combustion. To achieve the necessary speed, starter motors, coupled to a flywheel of the engine, turn or spin a crankshaft and a camshaft of the engine. This causes the pistons to actuate within each piston's cylinder. Prior to top dead center, a fuel injector injects fuel into the cylinder to allow the upward moving piston to compress it and cause ignition of such fuel (i.e., a compression-ignition engine). To prevent the likelihood of engine knock, the location of the piston within the cylinder is determined such that fuel is provided at the proper timing. Once proper combustion occurs, the starter motor disengages from the engine and the combustion process itself drives the pistons to provide the mechanical power.
Whilst different to the subject-matter of the present disclosure, background art includes: US2012204827 , US2010275872 , US2006142927 , and US2007119403 .
US2012204827 describes a method for restarting an internal combustion engine with the aid of direct start and cylinder deactivation, a control unit, and such an internal combustion engine. The method describes switching between a cylinder deactivation mode, in which at least one cylinder of the internal combustion engine is deactivated, and a full count mode, and the internal combustion engine is operable in an automatic start-stop strategy having subsequent direct start. The method includes an automatic stop, the cylinders which participate in the subsequent direct start are operated without combustion in the cylinder deactivation mode during the previous driving operation.
US2010275872 describes a method for starting an internal combustion engine having at least one cylinder, an inlet and an outlet valve, and having a piston interacting with a crankshaft. The method includes the crankshaft moving in a predetermined rotational direction during normal operation of the internal combustion engine, the piston being located in an initial position, the piston being moved into a defined starting position against a normal rotational direction of the crankshaft by means of a drive, fuel being injected, and the fuel being ignited.
US2006142927 describes a method for starting an internal combustion engine having a sensor disk which is coupled to a crankshaft of the engine. The sensor disk has a marking via an alternating arrangement of teeth and tooth spaces. The engine has a first sensor and a second sensor each capable of generating an electric signal which may assume at least two signal levels, being associated with the sensor disk, one of the signal levels being associated with a tooth and the other signal level with a tooth space. A rising or falling signal edge of the one signal and the signal level of the other signal are used for determining the direction of rotation and increment of the angle of rotation of the crankshaft. The starting characteristics are improved in that the absolute crankshaft angle position is saved in a non-volatile memory when the engine is shut off.
US2007119403 describes a method and a device for control of an internal combustion engine at a start, a recording means determining the position of a piston of a cylinder which is beginning compression or entering an intake phase before the start of the internal combustion engine, and a calculation means specifying a starter torque as a function of this piston position.

SUMMARY

Described herein is an engine system including a crankshaft wheel having a plurality of teeth; a bi-directional sensor configured to record position data regarding the crankshaft wheel; and an engine control module. The engine control module is configured to receive an engine stop command, the engine stop command configured to shut down an engine; receive the position data from the bi-directional sensor; determine a stop position of the crankshaft wheel based on the position data when the engine is shut down; store the determined stop position of the crankshaft wheel; receive an engine restart command; and provide a command to restart the engine based on the determined stop position.
A first aspect of the present invention provides an apparatus structured to facilitate a relatively fast restart of an engine. The apparatus includes an engine stop module structured to receive a stop command, the stop command providing an indication of an engine transitioning to an off state; an engine position module structured to receive position data indicative of a position of a crankshaft of the engine, and determine a stop position of the crankshaft based on the position data when the engine is in the off state; an engine restart module structured to receive a restart command, the restart command providing an indication of the engine transitioning from the off state to an on state; and an engine ignition module structured to facilitate a restart of the engine to the on state responsive to the restart command, wherein the engine ignition module is structured to determine a first viable cylinder to begin combustion in based on the determined stop position of the crankshaft and a firing order for the engine, wherein the first viable cylinder is a cylinder immediately following a cylinder that would have experienced a next combustion event according to the firing order but for the engine reaching the off state. Advantageously, the engine control module is structured to continuously count teeth on a crankshaft wheel to correct a "half-cycle" of the camshaft to eliminate a conventional indexing step included in conventional restart systems.
Also described is an engine system including an engine control module. The engine control module is configured to receive an engine stop command, the engine stop command configured to shut down an engine; receive position data from a bi-directional sensor; determine a stop position of a crankshaft wheel based on the position data; store the determined stop position of the crankshaft wheel; receive an engine restart command; and provide a command to begin a combustion event in a cylinder of the engine system based on the determined stop position and the engine restart command.
Yet another aspect of the present invention relates to a system. The system comprises the apparatus of the first aspect of the present invention and includes an engine having a crankshaft coupled to a crankshaft wheel, such that the crankshaft and crankshaft wheel rotate in sync; a sensor structured to acquire position data regarding a position of the crankshaft wheel; and an engine control module communicably coupled to the sensor, the engine control module including the engine stop module, the engine position module, the engine restart module, and the engine ignition module, the engine control module structured to: receive, by the engine stop module, an engine stop command, the engine stop command configured to shut down the engine; receive, by the engine position module, the position data from the sensor; determine, by the engine position module, a stop position of the crankshaft wheel based on the position data when the engine is shut down; receive, by the engine restart module, an indication of an engine restart; determine, by the engine ignition module, a first viable cylinder to begin combustion in based on the determined stop position of the crankshaft wheel; and provide a command to initiate combustion in the first viable cylinder to restart the engine.
Also described is a tangible, non-transitory computer-readable storage medium having machine instructions stored therein, the instructions being executable by a processor to cause the processor to perform operations including: receiving an engine stop command; determining a stop location of a crankshaft wheel based on counting teeth of the crankshaft wheel; receiving an engine restart command; and providing a command to restart the engine based on the determined stop location.
A further aspect of the present invention relates to a method for facilitating a relatively fast engine restart. The method includes receiving, by an engine control module, an engine stop command in a vehicle, the engine stop command structured to shut down an engine of the vehicle; receiving, by the engine control module, position data from a bi-directional sensor, the position data indicative of a position of a crankshaft wheel; determining, by the engine control module, a stop position of the crankshaft wheel based on the position data when the engine is shut down; determining, by the engine control module, a first viable cylinder of the engine to restart combustion in based on the determined stop position of the crankshaft wheel wherein the first viable cylinder is based on a firing order for the engine, wherein: the first viable cylinder is based on a firing order for the engine, wherein the first viable cylinder is a cylinder immediately following a cylinder that would have experienced a next combustible event according to the firing order but for the engine reaching the off state; and receiving, by the engine control module, an engine restart command, the engine restart command structured to restart the engine beginning with initiation of combustion in the first viable cylinder.
These and other features, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a schematic diagram of an internal combustion engine system for a vehicle, according to an example embodiment.
FIG. 1B is a schematic diagram of an engine position system, according to an example embodiment.
FIG. 2 is a schematic diagram of an engine control module for the systems of FIGS. 1A-1B, according to an example embodiment.
FIG. 3 is a schematic diagram of stop positions for a crankshaft wheel, according to an example embodiment.
FIG. 4 is a schematic diagram of camshaft wheel position in comparison to crankshaft wheel position, according to an example embodiment.
FIG. 5 is a schematic diagram of camshaft wheel position as a function of crankshaft wheel tooth position, according to an example embodiment.
FIG. 6 is a schematic diagram of combustible event locations as a function of engine stop locations, according to an example embodiment.
FIG. 7 is a flow diagram of a method of restarting an internal combustion engine, according to an example embodiment.
FIG. 8 is a graph of an engine utilizing the method of FIG. 7, according to an example embodiment.
FIG. 9 is a schematic diagram of a piston-cylinder configuration communicatively coupled to an engine control module, according to an example embodiment.
FIG. 10 is a schematic diagram of utilizing an offset with the determined engine stop location to enable an engine restart, according to an example embodiment.
FIG. 11 is a schematic diagram of an example of using offset values with determined engine stop locations in conjunction with pre-calibrated top dead center locations, according to an example embodiment.

DETAILED DESCRIPTION

Referring to the Figures generally, the various embodiments disclosed herein relate to systems and methods of determining an engine stop location to enable a fast restart of the engine. To improve fuel economy, an internal combustion engine of a vehicle may shut down when at an extended stop while the ignition remains in the "ON" position (i.e., an operator has not turned the key to an "OFF" position). For example, when the vehicle is at a stop light, the driver of the vehicle may depress the brake pedal which shuts down the engine because the brake pedal is depressed for longer than a predetermined amount of time (e.g., longer than two seconds, etc.). Rather than continuous operation, periodic in-operation leads to fuel savings. However, to avoid extended stops before the engine restarts to prevent unnecessary delays, engine restarts need to be relatively fast. Relatively fast referring to engine restarts in about less than or equal to 0.5 seconds (approximately the time it takes for an operator to remove his/her foot from the brake pedal and press the accelerator pedal). The systems and methods described herein facilitate relatively fast engine restarts by determining the exact engine stop location, determining the first viable combustion cylinder, and providing commands to initiate combustion in that cylinder responsive to receiving an engine restart command.
As mentioned above, engine restart is a function of engine location and engine speed. A starter motor is used to turn the engine to achieve a sufficient speed. When the location is correct (i.e., where the piston is positioned in the cylinder and the direction of movement of the piston, such as just before top dead center), fuel is injected to cause combustion. If fuel is injected at an inappropriate time (e.g., during the intake stroke), fuel may build up within the cylinder, which may prevent combustion and cause engine damage. Typically, engine startup requires synchronization of the engine crankshaft and camshaft. After synchronization, the engine monitoring system may report engine speed and begin processing fueling/injection commands into the cylinders. Accordingly, engine startup requires rotation of the engine (using the starter motor), detection of the crankshaft wheel index (described herein), and correction of the engine "half cycle" (also described herein) based on the detection of the camshaft index before fueling/injecting commands are possible and sustainable combustion occurs.
The present disclosure describes systems and methods of determining and memorizing the exact engine stop location to enable a quick restart of the engine by eliminating the traditional indexing step. As described herein, when an engine is shutting down, the engine tends to oscillate before coming to rest. According to the present disclosure, a bi-directional sensor is utilized to monitor the oscillation of a crankshaft wheel during shut down to determine an exact stop location. The determined engine stop location is memorized in a controller (e.g., engine control module) of the vehicle. When an operator initiates an engine restart (e.g., pressing the accelerator pedal, releasing the brake pedal, etc.), based on the determined stop location, the controller determines the first viable combustion cylinder to achieve sustainable combustion.
In some embodiments, the controller of the present disclosure dynamically adjusts the location of the piston in the first viable combustion cylinder responsive to at least one of a predetermined amount of time that the engine is OFF and/or a change of temperature and pressure in the first viable combustion cylinder. During extended periods of shut down, the pressure and temperature in the cylinder tend to decrease towards ambient conditions. As a result, the oxygen available for combustion decreases. Accordingly, the controller of the present disclosure dynamically adjusts the piston closer to bottom dead center in the first viable combustion cylinder to provide a relatively larger volume for additional oxygen molecules to be added to promote combustion in the first viable combustion cylinder. The controller may utilize this feature independent of or in combination with the aforementioned quick restart feature. Advantageously, using this dynamic feature enables the controller of the present disclosure to facilitate sustainable combustion in the engine to decrease the likelihood of unwanted engine restart conditions, such as knock. These and other features are described more fully herein.
As used herein, the term "engine position" refers to the position of the crankshaft for an internal combustion engine, which can be indicated by a position of a crankshaft wheel (e.g., a crankshaft wheel tooth number). Because the crankshaft wheel is coupled to the crankshaft, the rotation of the crankshaft is the same as that of the crankshaft wheel. The crankshaft is also coupled to the camshaft via, for example, a belt, such that the position of the crankshaft also corresponds with a specific position of the camshaft. In an internal combustion engine, the crankshaft is coupled to one or more pistons and the camshaft is in operative communication with one or more valves (e.g., intake valve) of the engine. Accordingly, the engine position includes various and different positions of the piston(s) and valves based on the position of the crankshaft and camshaft, respectively. For example, the position of the crankshaft wheel may indicate an engine position of bottom dead center for the piston of cylinder number three, top dead center for the piston of cylinder number two, and in between bottom and top dead center for the pistons of cylinder numbers one and four (a four cylinder engine). This position may also indicate the position of the valves for each of the four cylinders. Accordingly, an engine control module may control fuel injecting/spark ignition for the cylinders based on this position. For example, the engine control module may ready the ignition coil (for a spark for a spark ignition engine) and/or fuel injector for cylinder number three as the piston begins its ascent to top dead center. As such, engine position includes the position of the crankshaft and camshaft based on the position of the crankshaft wheel.
Referring now to FIGS. 1A-1B, an internal combustion engine system 100 for a vehicle (FIG. 1A) and an engine position system (FIG. 1B) are shown according to example embodiments. The vehicle may be an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up truck), sedans, coupes, compacts, sport utility vehicles, and any other type of vehicle that may utilize a fast restart management system of the present disclosure. As shown, the internal combustion engine system includes a battery 101, a motor/generator 102, a transmission 103, accessories 104, an engine 105, and an engine control module (ECM) 130. Communication between and among the components of the engine system 100 and engine position system 150 may be via any number of wired or wireless connections. In one embodiment, a controller area network (CAN) bus provides the exchange of signals, information, and/or data among at least the components shown in FIGS. 1A-1B. The CAN bus includes any number of wired and wireless connections. For example, a wired connection may include a serial cable, a fiber optic cable, a CAT5 cable, or any other form of wired connection. In comparison, a wireless connection may include the Internet, Wi-Fi, cellular, radio, etc. Because the ECM 130 is communicably coupled to the systems and components shown in FIGS. 1A-1B, the ECM 130 may receive various pieces of data and actuate one or more actuators (e.g., cause the fuel injector to inject fuel at a specific time, etc.) based on one or more pieces of data received by the ECM 130.
The battery 101 or energy storage device may be of any configuration (e.g., a 12 Volt battery, etc.). As shown, the battery 101 is electrically coupled to an electrical system 106 and the ECM 130. The battery 101 is structured provide electrical energy to the electrical system 106 and the ECM 130. The electrical system 106 may include one or more converters, inverters, relays, junction boxes, and the like. The electrical system 106 is structured to provide the electrical energy to one or more components within the vehicle. As shown, the electrical system 106 facilitates power transmission to the motor/generator 102.
The motor/generator 102 engages with the engine 105 to rotate a crankshaft of the engine to start the engine 105. As shown, the motor/generator 102 is a device that is operable in a motoring mode and a generating mode. During motoring, the motor is powered from electrical current from the battery 101 while, during generating, the generator generates electrical output current that may be stored for future use by the battery 101 or transmitted directly to a component. During operation, at least one of the engine 105 and the motor 102 provide power directly or indirectly to one or more vehicle accessories 104 (e.g., oil pump, air compressor, coolant pump, power steering, air conditioning system, cooling fan, transmission fluid pump, etc.). As shown, this power transmission is via one or more belts 107 coupled to the accessories 104 and the motor/generator 102.
In the example depicted, the engine 105 is communicably coupled to the ECM 130. The engine 105 is also coupled to a clutch 108 and a torque converter or clutch 109. The torque converter or clutch 109 serves as intermediary between the engine 105 and the transmission 103. The clutch 108 and clutch 109 may be of any type of clutch. Similarly, the engine 105 may be of any size (e.g., four cylinder, six cylinder, etc.) and type. For example, the engine 105 may be a compression-ignition engine or a spark-ignition engine. As such, the engine 105 may be powered by any fuel type (e.g., diesel, ethanol, gasoline, etc.). Similarly, the transmission 103 may be structured as any type of transmission, such as a continuous variable transmission, a manual transmission, an automatic transmission, an automatic-manual transmission, a dual clutch transmission, etc. Accordingly, as transmissions vary from geared to continuous configurations (e.g., continuous variable transmission, etc.), the transmission can include a variety of settings (gears, for a geared transmission) that affect different output speeds based on the engine speed. For simplicity, the engine described herein is in regard to a compression-ignition engine.
As a brief overview, the engine 105 receives a chemical energy input (e.g., a fuel such as gasoline, diesel, etc.) and combusts the fuel to generate mechanical energy, in the form of a rotating crankshaft. The transmission 103 receives the rotating crankshaft (via the clutch 109) and manipulates the speed of the crankshaft to affect a desired drive shaft speed. The rotating drive shaft is received by a differential, which provides the rotation energy of the drive shaft to the final drive. The final drive (e.g., wheels) then propels or moves the vehicle.
During operation, rotation of the crankshaft of the engine causes a crankshaft position wheel 120 (FIG. 1B) to rotate in sync with the crankshaft. Accordingly, referring more particularly to FIG. 1B, an engine position system 150 is shown according to an example embodiment. The engine position system 150 includes a sensor, shown as bi-directional sensor 110, and a rotary engine position tone wheel, shown as crankshaft wheel 120. The sensor 110 is communicatively coupled to the ECM 130. The crankshaft wheel 120 is coupled to a crankshaft, which is connected to one or more connecting rods that are connected to one or more pistons of the engine 105. Accordingly, as the crankshaft rotates, the crankshaft wheel 120 rotates in sync with the crankshaft. The rotary position tone wheel may include shutter blades, notches, protrusions, or any other type of device that generates an output signal from the sensor 110 as the wheel rotates.
As shown, the crankshaft wheel 120 is structured as a gear that includes a plurality of teeth 122. In certain other embodiments, the crankshaft wheel 120 may be structured in any manner that enables the position of the crankshaft to be monitored. In the example shown and described herein, the crankshaft wheel 120 is configured as a 60-2 gear (60 teeth with 2 teeth missing to provide an index part). The two missing teeth serve as an index for the crankshaft wheel 120. In traditional systems, the engine position sensor must first observe/locate the index location prior to synchronizing the crankshaft with the camshaft to enable combustion and engine restart. Although the systems and methods described herein are in regard to the configuration of the crankshaft wheel 120 shown in FIG. 1B, the same or similar systems and methods may be utilized with crankshaft wheels of all shapes (e.g., 12-2 (twelve teeth with two missing), 32-2, etc.). Advantageously, the systems and methods of the present disclosure may facilitate the removal of an indexing location in a crankshaft wheel thereby reducing the need for manufacturing equipment used to create the index location and expensive instrumentation used to identify the index location in use.
According to the present disclosure, the sensor is structured as a bi-directional sensor 110 that obtains position data regarding the position of the crankshaft wheel 120. The bi-directional sensor 110 monitors the position of the crankshaft wheel 120 (i.e., rotary tone wheel 120) in two directions of rotation (i.e., forward and reverse). In certain embodiments, the sensor 110 may also monitor the speed of the crankshaft wheel 120 (corresponding to engine speed revolutions-per-minute ("RPM")). The sensor 110 may be mounted on the main crankshaft pulley, the flywheel, on the crankshaft itself, etc. In other embodiments, the sensor 110 may be in any position where the sensor 110 may monitor and detect the position of crankshaft wheel 120. The bi-directional sensor 110 may be structured as a hall effect sensor, a flexion-type sensor (e.g., fiber-optic, polymer-based, etc.), or any other type of bi-directional sensor. As a hall effect sensor, the sensor 110 may receive supply voltage from the battery 101, such that a constant voltage may be produced. The output voltage (i.e., a signal, such as a square wave) from the sensor 110 then varies based on position of the crankshaft wheel 120 (i.e., whether a tooth of the crankshaft wheel 120 enters the magnetic field of the sensor 110). During operation, the sensor 110 obtains position data regarding the position of the crankshaft wheel 120 and transmits the position data to the ECM 130 (e.g., engine position module 135). In some engine systems, a camshaft position sensor 210 (see FIG. 4) may also be utilized to determine the position of the camshaft. In which case, the ECM 130 may also receive camshaft sensor position data 212 from the camshaft sensor 210. Based in part on the position data, the ECM 130 of the present disclosure facilitates a relatively quicker restart than conventional systems.
As the components of FIGS. 1A-1B are shown to be embodied within a vehicle, the ECM 130 may also include or be integrated (e.g., communicably coupled) with other control units in the vehicle. For example, the ECM 130 may include, but is not limited to, an exhaust aftertreatment control unit, a powertrain control module, and any other electronic control module. Further, these units may be embodied within a controller for the vehicle. The function and structure of the ECM 130 is explained more fully in regard to FIG. 2 (with reference to FIGS. 1A-1B).
Accordingly, referring now to FIG. 2, the function and structure of the ECM 130 are shown according to an example embodiment. The ECM 130 is shown to include a processing circuit 131 including a processor 132 and a memory 133. The processor 132 may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital signal processor (DSP), a group of processing components, or other suitable electronic processing components. The one or more memory devices 133 (e.g., RAM, ROM, Flash Memory, hard disk storage, etc.) may store data and/or computer code for facilitating the various processes described herein. Thus, the one or more memory devices 133 may be communicably connected to the processor 132 and provide computer code or instructions to the processor 132 for executing the processes described in regard to the ECM 130 herein. Moreover, the one or more memory devices 133 may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the one or more memory devices 133 may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.
The memory 133 is shown to include various modules for completing the activities described herein. More particularly, the memory 133 includes modules structured to memorize the exact or substantially the exact engine stop location to enable a quick restart of the engine. While various modules with particular functionality are shown in FIG. 2, it should be understood that the ECM 130 and memory 133 may include any number of modules for completing the functions described herein. For example, the activities of multiple modules may be combined as a single module, as additional modules with additional functionality may be included, etc. Further, it should be understood that the ECM 130 may further control other vehicle activity beyond the scope of the present disclosure.
Certain operations of the ECM 130 described herein include operations to interpret and/or to determine one or more parameters. Interpreting or determining, as utilized herein, includes receiving values by any method known in the art, including at least receiving values from a datalink or network communication, receiving an electronic signal (e.g. a voltage, frequency, current, or PWM signal) indicative of the value, receiving a computer generated parameter indicative of the value, reading the value from a memory location on a non-transient computer readable storage medium, receiving the value as a run-time parameter by any means known in the art, and/or by receiving a value by which the interpreted parameter can be calculated, and/or by referencing a default value that is interpreted to be the parameter value.
As shown in FIG. 2, the ECM 130 includes an engine stop module 134, an engine position module 135, an engine restart module 136, an engine adjustment module 137, a communications module 138, and an engine ignition module 139. As shown in FIGS. 1-2, the ECM 130 is structured to receive a plurality of inputs (e.g., data, signals, etc.) and is communicably coupled to a variety of components within the system 100, such as the engine 105 in FIG. 2. The ECM 130 is shown to receive data 160, the data 160 is shown to include an operator switch, a vehicle speed, a brake pedal position, a gear selector position, other vehicle information, an air pressure. These values may be received from one or more sensors positioned proximate to each respective component. As shown in FIG. 2, the ECM 130 is also structured to receive a restart command 163, position data 161, and a stop command 162.
The communications module 138 is structured to facilitate communication with an operator of the vehicle. Accordingly, the communications module 138 may be communicatively coupled to one or more input/output devices (e.g., a touchscreen, etc.) included with the vehicle. Further, the communications module 138 may also be communicably coupled to one or more lamps 111 (FIG. 1A). The lamp 111 may provide a notification to an operator of the vehicle (e.g., a check engine light, a warning light, etc.).
The engine stop module 134 is structured to receive a stop command 162 (e.g., data, a signal, etc.) for the engine 105. The stop command 162 provides an indication of the engine stopping (e.g., coming to rest, being turned OFF, shut down, transitioning to an OFF state, etc.) while the key of the vehicle remains in the "ON" position. Accordingly, the stop command 162 includes, but is not limited to, a depression of the brake pedal, an actuation of an "engine shut off' button, etc. In the OFF state, spark (for a gasoline engine) and fueling is prevented to the engine. However, the electrical system 106 remains operational.
The engine position module 135 is structured to receive position data 161. The engine position module 135 is also structured to determine the engine position based on the position data. This determination also includes correcting the "half-cycle" of the engine to sync the camshaft with the crankshaft, as described below. The position data 161 is indicative of a position of the crankshaft (e.g., crankshaft wheel 120 of FIG. 1B). According to the present disclosure, the position data 161 is acquired by the bi-directional sensor 110 and transmitted to the ECM 130. With reference to FIGS. 1B and 3-6 and as mentioned above, the position data is detected by the bi-directional sensor 110 and corresponds with a position of the crankshaft wheel 120 (e.g., a tooth number). Due to the ability of the bi-directional sensor 110 to acquire data indicative of both a forward and reverse direction of rotation, the bi-directional sensor 110 is able to sense a change of direction after engine shutdown is initiated. In other words, during operation of the vehicle, the crankshaft wheel 120 rotates clockwise which corresponds with a forward movement of the vehicle (counterclockwise for reverse). While the engine is stopping, the engine (pistons/crankshaft) rotates forwards and backwards. Traditionally, this reverse rotation is undetected. Accordingly, when restarting, a traditional sensor first locates the index location on a crankshaft triggering wheel (i.e., the two-tooth gap), begins counting the crankshaft wheel teeth, and matches the counted crankshaft wheel tooth number with a pre-determined camshaft wheel tooth number (i.e., traditional syncing). As soon as the engine position is identified, fuel is injected into the cylinder where top dead center is approaching to begin combustion. As mentioned above, this traditional syncing process is time-consuming and substantially prevents quick engine restarts.
As mentioned above, the bi-directional sensor 110 may be configured as a hall-effect sensor. Accordingly, each time a tooth passes the sensor, the sensor detects a leading edge and a magnetic field is induced. The induced charge is converted by the sensor 110 to an "ON" signal. The magnetic field disappears (no induction) during gaps between the teeth, which the sensor 110 converts to an "OFF" signal. The "ON" and "OFF" signals are provided to the ECM 130 (i.e., position data 161). To determine whether the engine has rotated in a reverse direction, the engine position module 135 determines whether the induced field is accelerating (forward direction) or decelerating (reverse direction). For example, the engine position module 135 (or bi-directional sensor 110 in some embodiments) monitors the change in magnetic field strength and/or time duration based on the direction of rotation. Because the engine speed is relatively slower in the reverse direction than in the forward direction, the bi-directional sensor 110 provides a relatively longer duration signal that is indicative of a forward rotation direction than for a reverse rotation direction. In the example embodiment depicted in the Figures, forward direction rotation (i.e., clockwise) corresponds with a 47 microsecond time-based pulse width signal whereas reverse direction rotation (i.e., counterclockwise) corresponds with a 94 microsecond time-based pulse width signal. The pulse lengths are based on a diesel compression-ignition six-cylinder engine, where the forward direction has about a 9,000 RPM top engine speed and the reverse direction is about 4,500 RPM. Other engines may operate at different speeds thereby utilizing different pulse width signals (e.g., durations) to indicate forward/reverse directions. In this regard, the engine position module 135 uses a position data that is time-based to determine the exact position of the crankshaft wheel 120.
In other example implementations, the sensor 110 monitors the crankshaft wheel 120 tooth profile to determine a change in rotation directions. For example, the teeth of the crankshaft wheel 120 may be angled on one side, such that the sensor 110 induces a different signal (i.e., voltage) based on if the angled tooth profile is detected or the relatively flat profile is detected. All such variations are intended to fall within the scope of the present disclosure.
In operation, due to engine balancing, the crankshaft wheel 120 will come to rest at repeatable locations (i.e., stop locations). Per one revolution of the crankshaft wheel 120, in a six-cylinder engine has three stop locations, whereas a four-cylinder engine has two stop locations. Referring to FIG. 3, stop positions for the crankshaft wheel 120 are shown according to an example embodiment. Referring to FIG. 4, camshaft wheel positions are shown in comparison to crankshaft wheel positions according to an example embodiment. Because the camshaft wheel 200 rotates at half the speed of the crankshaft wheel 120, the crankshaft wheel 120 makes two revolutions for every one revolution of the camshaft wheel 200. Using a 60-2 crankshaft wheel 120 example, the first revolution corresponds with a tooth count of 0-59 (first "half cycle" for the camshaft 200). The second revolution corresponds with a tooth count of 60-119 (second "half cycle" for the camshaft 200). With this example, each tooth corresponds to six degrees (hence, one revolution of sixty teeth of the crankshaft wheel 120 is equal to three hundred and sixty degrees (360°)). Accordingly, all cylinders of the engine will fire (i.e., experience a combustible event) every two revolutions of the crankshaft wheel 120 and every one revolution of the camshaft wheel 200.
However, as is better seen in FIG. 5, the camshaft wheel 200 tooth pattern is different for each crankshaft revolution (i.e., each half-cycle of the camshaft wheel 200). This difference indicates the engine half-cycle that the engine position module 135 corrects in order to sync the camshaft with the crankshaft. As an example, a crankshaft wheel 120 tooth number of forty corresponds with a different crankshaft location and, in turn, camshaft position, based on if tooth number forty is encountered during the first revolution or the second revolution. In the first revolution, crankshaft wheel tooth forty is between camshaft wheel teeth one and two. In comparison, in the second revolution, tooth forty corresponds with tooth one-hundred, which is in between camshaft wheel teeth four and five. If this difference in position is not accounted for (i.e., determination of first half cycle or second half cycle), fuel may be injected into one or more cylinders not expecting fuel, which may lead to fuel build up and potential engine damage. As such, the position of the crankshaft must be synced with that of the camshaft prior to fuel being injected. The engine position module 135 is structured to count the teeth on the crankshaft wheel 120 to determine whether the crankshaft wheel is on the first or second revolution (i.e., to sync the crankshaft with the camshaft and correct the engine half-cycle). Accordingly, the engine position module 135 is structured to correct the engine "half cycle" by continuously counting the crankshaft wheel 120 teeth during shutdown to constantly determine whether the camshaft is on the first revolution or the second revolution.
Thus, via the bi-directional sensor 110, the engine position module 135 accounts for engine oscillation to determine the exact engine position without the need of the initial indexing. While the engine is running, the bi-directional sensor 110 is continuously counting the crankshaft wheel 120 teeth. This counting continues while the engine is stopping. During engine shut down, the moment a different direction is sensed (i.e., a different pulse width signal is provided to the ECM 130) by the bi-direction sensor 110, the engine position module 135 determines an initial stop location and begins counting teeth of the crankshaft wheel 120. The initial stop location corresponds with the crankshaft wheel 120 tooth number immediately prior to the change in direction. The tooth counting is then in relation to this initial stop location tooth number. Tooth counting by the ECM 130 is based on the number of different signals (i.e., forward and reverse direction signals) received by the ECM 130. When no more teeth are sensed, the engine position module 135 determines the exact stop location of the crankshaft wheel 120.
The engine restart module 136 is structured to receive a restart command 163. The restart command 163 is indicative of a desire to restart the engine. Accordingly, the restart command 163 may include, but is not limited to, a depression of the accelerator, a push of a button or a switch, a voice command, a release of the brake, etc.
The engine ignition module 139 is structured to facilitate the engine restart (i.e., transition the engine from the OFF state to an ON state). Accordingly, the engine ignition module 139 is structured to provide one or more commands to the engine 105 and ignition systems associated with the engine 105 to restart the engine. The commands may include, but are not limited to, a fuel injection quantity and timing (e.g., which cylinder) command, a spark command (for a spark-ignition engine), an actuation of intake/exhaust valves, an actuation of the motor/generator 102 to turn the crankshaft, etc.
Responsive to the determined position of the crankshaft, the engine ignition module 139 is structured to determine an initial cylinder (i.e., the first viable combustion cylinder) to begin combustion in to initiate the engine restart. FIG. 6 is a schematic diagram of combustible event locations and engine stop locations as a function of crankshaft wheel position according to an example embodiment. FIG. 6 depicts a firing order for the engine, according to an example embodiment. It should be understood that other engines may have different firing orders, but the systems and methods described herein are still applicable to these engines. In the example of FIG. 6, the combustible event locations are denoted as "CTDC" (compression at top dead center). As mentioned above, the examples described herein relate to compression-ignition engines such that combustion occurs at high pressure points (i.e., at or near top dead center). The number after "CTDC" (e.g., CTDC#5) refers to a specific cylinder (e.g., cylinder number five). With each tooth corresponding to six degrees, the distance between two stop positions is one-hundred twenty degrees (i.e., stop 1/1 is at tooth count number 0 and stop 2/1 is at approximately tooth count number 20; 20 tooth difference x 6 degrees/tooth equals 120 degrees). The distance between two top dead center positions is also one-hundred twenty degrees. Accordingly, in the example of FIG. 6, the distance between a stop location and a combustible event location is approximately sixty-degrees (e.g., stop #1/1 to CTDC#1). Moreover, each stroke of the piston in a cylinder is one-hundred and eighty degrees (i.e., from bottom dead center to top dead center). To initiate combustion, a sufficient speed of the engine and fuel injected at the proper location is required. The engine ignition module 139 is structured to determine the first viable combustion cylinder based on the determined engine stop location. The first viable combustion cylinder is a cylinder that can meet the requirements for sustainable combustion (e.g., engine speed, pressure, temperature, etc.).
As an example and with reference to FIG. 6, suppose the engine is shutting down and the bi-directional sensor 110 has counted to tooth number five for a six-cylinder compression-ignition engine in the forward direction. After reaching tooth number five, the bi-directional sensor 110 measures a 94 microsecond pulse width, which indicates that the crankshaft wheel 120 has reversed directions. Accordingly, tooth number five is the anchor position (i.e., initial stop position) where teeth are added to or subtracted from. As mentioned above, this anchor position is based on the first realization (i.e., a different pulse width signal) of a change in a direction while the engine is shutting down. While the engine is continuing to stop, the bi-directional sensor 110 then records the following signal: 94 microseconds - "OFF" (gap in between teeth) - 94 microseconds - "OFF' - 47 microseconds - "OFF' - 94 microseconds - 47 microseconds - "OFF" - 47 microseconds - "OFF" - 47 microseconds - "OFF." In total, the bi-directional sensor 110 records four 47 microsecond pulse widths and three 94 microsecond pulse widths. The ECM 130 adds one tooth (four teeth in the forward direction minus three teeth in the reverse direction) to the anchor position for a determined stop location of the crankshaft wheel 120 of tooth number six. As shown in FIG. 6, for the firing order of this engine, the earliest combustible event location for a restart would be in cylinder number one (i.e., CTDC#1). CTDC#1 is at approximately crankshaft wheel tooth number eleven and the determined engine stop location is at tooth six. In turn, the piston in cylinder number one is at one-hundred and fifty degrees (i.e., 180° (piston at top dead center) - (tooth 11 - tooth 6)^∗6°/tooth = 150°). Thus, combustion in cylinder number one would need to occur based on a thirty-degree stroke of the piston. Therefore, the engine ignition module 139 determines that the first viable cylinder location is cylinder number five.
To determine the first viable combustion cylinder, the engine ignition module 139 may utilize a variety of predefined standards. In one disclosed configuration, the predefined standard corresponds with a minimum piston stroke (e.g., fifty degrees). In the above example, thirty degrees is less than the minimum (for cylinder one), so the first viable combustion cylinder is combustion is the next cylinder encountered in the predefined combustion order for the engine (i.e., firing order): cylinder number five. But, in the above example, if the determined stop location is tooth one (corresponding to a piston stroke of sixty degrees) then the first viable cylinder would be determined by the engine ignition module 139 to be cylinder number one. In another embodiment, the predefined standard is a skip cylinder protocol. For example, if the next cylinder that would have experienced a combustible event is cylinder three (see FIG. 6) when engine shutdown occurred, the first viable cylinder is cylinder six (e.g., cylinder three was skipped). In another configuration, the predefined standard is based on the determined stop position relative to an assigned cylinder for the determined stop position. For example, the assigned cylinder for teeth number one to fifteen is cylinder five while teeth number fifteen to thirty-five is cylinder three (see FIG. 6). Accordingly, as can be readily appreciated, many different standards may be used with all such variations intended to fall within the scope of the present disclosure. In still other configurations, the first viable cylinder is modified by the structure and function of module 137, which is described below.
In operation, the engine stop module 134, the engine position module 135, the engine restart module 136, and the engine ignition module 139 facilitate a relatively faster restart of the engine relative to conventional systems. By determining the exact stop location of the engine using a bi-directional sensor and then determining the first viable cylinder relative to the determined stop location, the ECM 130 of the present disclosure may eliminate an indexing step that is traditionally required to determine the position of the crankshaft and enable a faster engine restart.
To enhance the performance of the modules 134, 135, 136, and 139, in some embodiments, an engine adjustment module 137 is included in the ECM 130. The engine adjustment module 137 is structured to adjust a position of one or more pistons in one or more cylinders of the engine. According to one embodiment, the piston adjusted is the piston of the first viable combustion cylinder. In this regard, the engine adjustment module 139 provides dynamic control over the engine while it is in the OFF state to facilitate a relatively fast engine restart. In one embodiment, operation of the engine adjustment module 139 occurs based on at least one of a passage of a predefined amount of time from when the engine was turned OFF (i.e., while the engine is OFF) and a decrease in at least one of a temperature and pressure in the first viable combustion cylinder by more than a predefined acceptable amount (relative to the initial temperature and pressure when the engine was turned OFF). In regard to the time-based configuration, the engine adjustment module 137 is structured to rotate the crankshaft to rotate a piston closer to bottom dead center over time. The rotation amount may be based on a predefined time amount. For example, every ten seconds that the engine is OFF, the engine adjustment module 137 rotates the piston ten degrees (10°) closer to bottom dead center. This rotation may continue until the piston reaches bottom dead center. In some embodiments, the piston may be stopped at eight degrees before bottom dead center, or another number less than the predefined rotation amount, such that the rotation is directly to bottom dead center following the passing of the predefined amount of time. Of course, the rotation amount and predefined amount of time are highly variable parameters that may be adjusted or preset via the manufacturer, a user, an operator of the vehicle, etc.
As mentioned above, in another embodiment, the adjustment may be based on at least one of a detected pressure and temperature in the cylinder. In this configuration, the engine adjustment module 137 is communicably coupled to temperature and pressure sensors positioned on or near each cylinder in the engine 105. The temperature and pressure sensors are structured to acquire temperature and pressure data indicative of the temperature and pressure within each cylinder. In operation, the engine adjustment module 137 receives temperature and pressure data at or near when the engine stop module 134 receives the stop command 162. This data represents an initial temperature and pressure in each of the cylinders. While the engine is OFF, the engine adjustment module 137 continues to receive the pressure and temperature data. If at least one of the pressure and temperature data indicates a change more than a predefined amount (e.g., the pressure has decreased by X percent), then the engine adjustment module 137 adjusts a piston position by a predefined amount. The adjustment amount may be predefined or may be set based on the detected pressure and/or temperature. For example a pressure of X atmospheres may correspond with a piston position at twelve (12) degrees above bottom dead center while a pressure of X-5 atmospheres may correspond with a piston position at six (6) degrees above bottom dead center. Thus, the decrease in pressure (and temperature, in accord with the ideal gas law) corresponds with the engine adjustment module 137 rotating the piston closer to bottom dead center. As in the time-based configuration, the final rotation position corresponds with the bottom dead center location.
In operation, when the engine is shut OFF, due to the insulation in the engine, pressure (and temperature) decreases in the cylinder towards ambient conditions. This correlates with a reduction in available oxygen for combustion when restart is commanded. As such, the engine adjustment module 137 is structured to rotate the piston(s) closer to bottom dead center to increase the volume within the cylinder to increase the intake amount of oxygen to facilitate combustion when commanded.
According to another embodiment, the adjustment may be based on at least one of a detected, estimated, or predicted amount of oxygen concentration or oxygen content in the cylinder. For example, the engine may have shut down when exhaust gas recirculation rates were high and the residual trapped gas has a low or relatively low oxygen concentration. In this embodiment, the engine adjustment module 137 may utilize at least one of detected (e.g., via an oxygen sensor proximate an intake manifold of the engine), determined, predicted, estimated, etc. amount of oxygen to account for changing in-cylinder characteristics based on operation of the exhaust gas recirculation system. In this regard, the engine adjustment module 137 may adjust the piston differently for high exhaust gas recirculation rates at the time of shut down than for low exhaust gas recirculation rates at the time of shut down. For high exhaust gas recirculation rates, the engine adjustment module 137 may cause an adjustment of the piston closer to bottom dead sooner than for low exhaust gas recirculation rates. This is due to the relatively higher amount of exhaust gas during high exhaust gas recirculation flow rates, which displaces oxygen otherwise used for combustion. Accordingly, more oxygen is needed following a shut down during high exhaust gas recirculation flow rates to facilitate to sustainable combustion for engine restart. Of course, the precise adjustment amount and timing (e.g., ten degrees closer to bottom dead center every one and a half seconds following shut down for high exhaust gas recirculation flow rates compared to five degrees closer to bottom dead center every two seconds following shut down for low exhaust gas recirculation rates, etc.) as well as the demarcations of high, low, normal exhaust gas flow rates is highly variable such that a wide range of possibilities are intended to fall within the scope of the present disclosure. Furthermore, this additional characteristic (oxygen amount or concentration) may be used independent of temperature and pressure or used in combination with temperature and pressure as basis for the adjustment.
In still another embodiment, the adjustment may be based on a predictive function of at least one of temperature and pressure within the first viable cylinder. The prediction function may utilize a variety of inputs, such as ambient temperature, fuel pressure, fuel injection timing, engine speed, etc. as a function of time that the engine has been in the off state. The prediction function may then model how the in-cylinder temperature and pressure of the first viable cylinder is expected to decay or decrease. In this regard, the prediction function may utilize one or more formulas, algorithms, look-up tables, processes, models, etc. Responsive to if the decay or decrease is by more than a predefined amount, the engine adjustment module 137 can adjust the piston position closer to bottom dead center.
In yet another embodiment, adjustment may be based on one or more fuel properties for the engine. This characteristic may be used with or independent of data indicative of an oxygen amount or concentration, temperature, and/or pressure for the first viable cylinder. Fuel properties can include, but are not limited to, a type of fuel, region where the fuel is supplied, season (e.g., summer, winter, fall, spring) when the fuel is supplied, and any other characteristic regarding the fuel itself. Utilizing the fuel properties, the engine adjustment module 137 considers that many properties of the fuel for the engine itself can change (e.g., ethanol characteristics change seasonally and regionally, diesel fuel additives change seasonally, etc.). Accordingly, the engine adjustment module 137 can determine the requirements for combustion following shutdown based on elapsed time, estimated or predicted decay of in-cylinder temperature or pressure, oxygen content, and the like further based on the fuel properties of the fuel. For example, based on the fuel properties of the fuel (and, possibly other in-cylinder characteristics), a relatively higher amount of oxygen may be needed for fuel A than for fuel B. Accordingly, if the engine uses fuel A, then the engine adjustment module 137 adjusts the piston in the first viable cylinder closer to bottom dead center relatively faster following shut down than for engines that use fuel B. Advantageously, utilizing this data represents a further refinement and enhancement for the engine adjustment module 137 to facilitate a relatively faster engine restart than in conventional systems.
An abbreviated example of operation in connection with the other modules of the ECM 130 may be described as follows. When the engine is turned OFF, the engine position module 135 determines an exact or substantially exact location of the crankshaft wheel. Based on this position, the engine ignition module 139 determines the first viable cylinder for location. However, the engine has now remained OFF for more than a predetermined amount of time. This has caused the pressure and temperature in the first viable combustion cylinder to adjust closer to ambient conditions. As a result, the engine adjustment module 137 adjusts the piston in the first viable combustion cylinder closer to bottom dead center to facilitate an increase in intake oxygen and sustainable combustion for engine restart in that cylinder. Thus, when the restart command 163 is received, the engine adjustment module 137 provides ignition commands for the first viable cylinder with a piston that has been dynamically adjusted to facilitate sustainable combustion. As a result, relative to conventional systems, the present disclosure not only provides for a quicker engine restart but also dynamically takes into consideration the changing conditions in the engine due to the engine being OFF. In turn, the present disclosure enables a relatively quicker, without sacrificing sustainability (that may otherwise adversely impact combustion due to undesirable conditions, such as knock), to restart the engine. Furthermore, as indicated in the above example, the piston in the first viable combustion cylinder is adjusted which still eliminates the need for the traditional indexing step. These aspects and features are explained in detail in regard to method 700 of FIG. 7.
Accordingly, referring now to FIG. 7, in conjunction with FIGS. 1-6, a method 700 of providing a fast restart of a stopped engine is shown according to an example embodiment. As described herein, method 700 is implemented with the ECM 130. Accordingly, method 700 may be executed by one or more processors in the ECM 130. Further, method 700 may be implemented with one or more of the modules shown in FIG. 2.
Method 700 begins by the ECM 130 (e.g., the engine stop module 134) receiving a stop engine command (701). As described above, the stop engine command includes any command that turns the engine off while the ignition key stays in the "ON" position. For example, the stop command may include depression of the brake pedal or the actuation of an "engine shut OFF" button. In either event, the engine of a vehicle turns OFF, but the ignition key position remains ON. Accordingly, power from the battery 101 can still be provided. Thus, after the stop engine command is received by the ECM 130, the ECM 130 (e.g., engine stop module 134) turns the engine of the vehicle OFF (or, actuates one or more shut down mechanisms to shut the engine down).
At process 702, the ECM 130 receives engine position data and at process 703, the ECM 130 determines the engine stop location based on the position data. As mentioned above, the position data is detected by the bi-directional sensor 110 and corresponds with a position of the crankshaft wheel 120 (e.g., a tooth number). Once a change of direction is sensed by the sensor 110 after engine shutdown is initiated, then the position data is based on the sensed direction of rotation of the crankshaft wheel 120. As described above, during shut down, the moment a different direction is sensed (i.e., a different pulse width signal is provided to the ECM 130) by the bi-direction sensor 110, the engine position module 135 determines an initial stop location and begins counting teeth of the crankshaft wheel 120. The initial stop location corresponds with the crankshaft wheel 120 tooth number immediately prior to the change in direction. The tooth counting is then in relation to this initial stop location tooth number. Tooth counting by the ECM 130 is based on the number of different signals (i.e., forward and reverse direction signals) received by the ECM 130. Thus, based on the different signals, the final determined stopped position is based on adding or subtracting teeth from the initial anchor position. This determined engine stop location is stored in the ECM 130 for when a restart process is initiated.
Bypassing processes 705-706, at process 704, the first viable cylinder for combustion is determined based on the determined engine stop location. As mentioned above, for sustainable combustion, a proper speed and conditions (e.g., temperature, pressure, quantity of fuel, quantity of fuel injected at the proper time) are required. Accordingly, as described above in regard to the engine ignition module 139, the first viable combustion cylinder may be determined according to one or more predefined standards. For example, the predefined standard may be based on a minimum piston stroke, based on skipping what would have been the next combustion cylinder if the engine was not deactivated, based on a predefined relationship for the determined tooth number (e.g., the determined tooth number corresponds with a specific combustion cylinder), etc. This list is not meant to be exhaustive as other standards, guidelines, preferences provided by a user, etc. may be used to determine the first viable cylinder for combustion to initiate combustion in when restart is commanded.
The determined first viable cylinder location is stored (e.g., in memory of ECM 130). Therefore, at processes 707-708, when engine restart is commanded and when a command is provided to restart the engine, the commands are provided to facilitate combustion in the determined first viable combustion cylinder. As described above, the restart command includes, but is not limited to, a release of the brake pedal, a depression of the accelerator, etc. In some embodiments, the restart command also includes a shift of gears (e.g., from neutral to first gear). In other words, the restart command initiates operation of the engine from the engine OFF position (with the ignition key in the on position). As also mentioned above, the commands to restart the engine may include, but are not limited to, actuating a fuel injector, actuating an ignition coil, actuating the starter motor, actuating an intake air valve, and any other commands used in beginning combustion in the engine.
The result of method 700 and the fast restart is shown in FIG. 8, according to an example embodiment. FIG. 8 shows Applicant-acquired data comparing the fast restart process of the present disclosure to a traditional restart process. The traditional restart process is shown by the group of lines indicated by reference numeral 310. The restart process described and disclosed herein is shown by lines 300. As shown, each process includes a dwell period (dwell period 320 for the restart process of the present disclosure and dwell period 330 for the traditional restart process). The dwell period is where no combustion is occurring, but the engine is turning and getting ready for fuel to be injected. The transition from the dwell period to the relatively more vertical lines indicates where combustion is beginning and occurring. The starter motor is responsible for the engine RPM during the dwell period. In this example, the engine is rotating at approximately 100 RPM prior to combustion. As shown, the dwell period 320 relatively smaller for the process of the present disclosure as compared to the traditional restart process. This contributes, at least in part, to a relatively faster restart process for the systems and methods described herein as compared to conventional systems Technically, this represents a substantial improvement over conventional systems. In particular, in this example, the dwell period 320 corresponds with 0.15 seconds whereas the dwell period 330 corresponds with approximately 0.30 seconds. Accordingly, there is at least a 0.15 second improvement with the process of the present disclosure relative to the traditional process.
To decrease the dwell period and enable combustion to occur even sooner, referring back to method 700, at process 705, the engine stop position may be changed. This aspect was described herein above in regard to the engine adjustment module 137. To further aid explanation, FIG. 9 shows a piston-cylinder combination 400 coupled to the ECM 130 for an engine. In FIG. 9, the piston 420 is at bottom dead center in the cylinder 410. During the compression stroke (as piston 420 moves toward top dead center where fuel injector 440 is located), one or more valves 430 (intake valve(s) or exhaust valve(s)) are typically not fully shut. Accordingly, a bleed out of gas contents in the cylinder 410 may occur. The valves 430 fully close while the piston 420 is ascending toward top dead center, sometime after bottom dead center. Accordingly, the gas volume used for combustion is less than the maximum cylinder volume. The dwell period 320 (FIG. 8) includes the time spent expelling the contents of the cylinder that are not used in the combustion event.
To achieve or substantially achieve the same or similar combustions at top dead center, a tradeoff is used between an initial sealed volume (when the valves are fully closed), an initial cylinder pressure, an expected internal pressure bleed off rate (e.g., via one or more valves 430), an actual stop position of the piston, environmental conditions (e.g., ambient temperature and pressure), and the like (collectively referred to as internal and external cylinder characteristics). To conduct this tradeoff, the ECM 130 (e.g., via the engine adjustment module 139) may utilize adiabatic and ideal gas laws. Bleed down refers to the pressure and temperature within the cylinder transitioning to ambient temperature and pressure. For example, a larger pressure difference between internal and external the cylinder may correspond with a faster bleed down rate as opposed to a smaller pressure difference. Each of these factors may affect the in-cylinder gas pressure, where a loss of pressure corresponds with the piston in the cylinder experiencing a relatively easier range of motion within the cylinder and an increase in pressure corresponds with a relatively harder range of motion within the cylinder. As such, due to bleed offs and the internal/ external pressures and temperatures, the piston may move within the cylinder (i.e., deviate from the determined stop location, process 705).
The ECM 130 may take this movement into consideration by adjusting the stop location of the piston to the sealed position (i.e., where the valves are fully closed and bleed off is minimized) to increase the fast restart and enable combustion (process 705). Thus, the ECM 130 may provide a command to change the determined stop condition based on at least one of an internal and external cylinder characteristic. At the sealed position, the movement of the piston toward top dead center compresses the in-cylinder gases rather than expels them because the valves are shut and bleed off is minimized. The stop position adjustment may be accomplished using a variety of control levers, such as variable-geometry turbocharger control valves, intake air throttle valves, and variable valve actuators. For example, increasing an opening of an air throttle valve may allow more air into the cylinder 410 to change the stop location. In-cylinder pressure measurements taken by, for example, a pressure sensor may be used by the ECM 130 to direct the control levers to adjust the stop position. After the stop position is changed, when a restart command is received (process 707) and the ECM 130 provides an engine restart command (process 708), the dwell period is decreased due to the elimination of time spent compressing gases that escape from a non-closed valve(s) 430. As such, the piston 420 only compresses gases used or mostly used in the combustion process.
As an example, suppose an engine stop command is received (process 701) and the engine is shutting down. But, an engine restart command (process 707) is not received for an extended period of time (e.g., twenty seconds). Based on the external cylinder characteristics and/or the valves not being fully shut, the in-cylinder gas contents have begun to transition to ambient pressure and temperature. But, the determined engine stop location (process 703) is at or near the sealed position for the first viable combustion cylinder (process 704), such that a relatively fast restart may be achieved at that location if a restart command is provided. However, due to the extended shut down period, the stop position may change from that relatively fast restart position (i.e., the sealed position). In turn, the ECM 130 may provide a command to change the determined stop condition based on the extended stop which has caused a bleed down of in-cylinder contents (i.e., the least one of an internal and external cylinder characteristic) to substantially back to the sealed position. In one implementation, the ECM 130 actuates the starter motor 102 to adjust the piston back to the sealed position. This sealed position may correspond with a particular crankshaft wheel 120 tooth number, such that the starter motor 102 rotates the crankshaft until the tooth number of the crankshaft wheel 120 is detected by the sensor 110. Accordingly, when the restart command is received (process 707) and the ECM 130 actuates the engine restart (process 708), the piston may act to compress the gas contents of the cylinder from the sealed position rather than from a non-sealed position that may have occurred from the bleed down. This may decrease the dwell period and lead to a relatively faster engine restart.
Thus, as mentioned above, the engine stop position may be changed based on at least one of a passage of a predefined amount of time from when the engine was turned OFF and a decrease in at least one of a temperature and pressure in the first viable combustion cylinder by more than a predefined acceptable amount (relative to the initial temperature and pressure when the engine was turned OFF). As also mentioned above, the engine position change may be based on or more predefined standards (e.g., ten degrees closer to bottom dead center every ten seconds of engine off time until bottom dead center is reached for the piston in the first viable combustion cylinder, etc.). Further, in some embodiments, the engine position change may be based on a predictive function. Advantageously, using a predictive function facilitates adjustment in advance of expected conditions to ready the engine for restart even faster than in conventional systems. Therefore, process 705 provides dynamic control over the engine to substantially achieve a fast engine restart.
In some embodiments, with gasoline or e85 engines, the quality of fuel comes into play. The same is true with regard to additives in diesel. Accordingly, in certain embodiments, the ECM 130 may receive data indicative of the fuel used in the engine and more particularly adjust the engine stop position (process 706) to achieve combustion in the first viable cylinder (process 708) responsive to the combustibility characteristics of the fuel. For example, at an extended engine OFF setting, gasoline may adjust to ambient conditions relatively faster than e85. Accordingly, the engine stop position may be adjusted to bottom dead center quicker and to a fuller extent in gasoline engines than in e85 engines. Thus, the present disclosure contemplates systems and methods of taking the fuel quality and type into consideration to further refine process 706.
Although processes 703-705 decrease the engine restart time, in some embodiments, the ECM 130 includes modules that prevent or substantially prevent implementing the next appropriate fuel injection process based on the determined or changed engine stop location. This is because a time processing unit (TPU) module, included with an ECM, may only be reset to "0" (i.e., the index location). For example, if the stop location is at tooth number forty, the TPU sets this as "0." The index location is then synced (i.e., the crankshaft wheel missing tooth gap is observed) prior to fuel being injected.
Accordingly, in certain embodiments, the ECM 130 adds an offset value to the determined stop location to generate an adjusted stop location (process 705), where this adjusted position is used for restarting. The offset value is equal to the determined stop location and may be adjusted when process 704 (change of engine position) is employed. Accordingly, FIG. 10 shows an example of inserting an offset value. In this example, the engine stopped at eighty degrees and the TPU reported this as zero degrees. Accordingly, the adjusted tooth count/angle is eighty degrees. As shown, in this case, one-hundred and ten degrees is used as the new top dead center angle, which corresponds with the actual top dead center position (i.e., one-hundred and ninety degrees). By utilizing an offset, the ECM 130 commands cylinder injection correctly, and allows for the bypassing a TPU module (if used). Advantageously, this aspect may be used to provide modularity to the systems and methods described herein, such that users and operators may implement these systems and methods with their current systems with minor adjustments and relatively smaller costs.
FIG. 11 depicts a further example of an offset utilized by ECM 130. The chart 1120 above the graph 1110 in FIG. 11 shows the pre-calibrated top dead center positions for each cylinder in the engine and the corresponding crankshaft wheel tooth number. As an example, suppose the engine stopped at crankshaft wheel 120 tooth ten (1130). Traditionally, the ECM 130 (or TPU) would report the crankshaft wheel at tooth twenty when it is at tooth thirty (top dead center in cylinder number five) during restart. Process 706 enables the ECM 130 to add the offset of ten to the stop position. When the ECM 130 (or TPU) reach tooth twenty while counting during the restart, this is accounted for as tooth thirty and not as tooth twenty. Accordingly, the ECM 130 commands the injectors to inject fuel at tooth twenty to enable a combustible event in cylinder number five and take advantage of the first viable combustion cylinder (process 708).
As mentioned above, method 700 is utilized while the ignition is in the "ON" position. In certain embodiments, during the first start of the engine, method 700 may be disabled because engine stop location information is not yet known. However, when the ignition is "ON," although the engine has turned OFF, power to ECM 130 is still provided such that the engine stop location is stored for fast restart of the engine (method 700). In an alternative embodiment, ECM 130 may store engine stop location information even after ignition is turned "OFF' (not during restart operation) to enable a relatively faster start-up of the engine when the engine and vehicle are restarted. A dedicated power source may be utilized with ECM 130 to store the engine stop location.
As mentioned above the method and Figures described herein were in regard to a diesel compression-ignition engine. However, the same method may be utilized with a spark-ignition engine. In this embodiment, the ECM would control power to the ignition coil to provide a spark and cause combustion (as compared to when and to what cylinder fuel is injected into in the compression-ignition case). It should be noted that the term "example" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
The schematic flow chart diagrams and method schematic diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of representative embodiments. Other steps, orderings and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the methods illustrated in the schematic diagrams.
Additionally, the format and symbols employed are provided to explain the logical steps of the schematic diagrams and are understood not to limit the scope of the methods illustrated by the diagrams. Although various arrow types and line types may be employed in the schematic diagrams, they are understood not to limit the scope of the corresponding methods. Indeed, some arrows or other connectors may be used to indicate only the logical flow of a method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of a depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and program code.
The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. As mentioned above, in certain embodiments, the ECM forms a processing system or subsystem that includes one or more computing devices having memory, processing, and communication hardware. The ECM may be a single device or a distributed device, and the functions of the processor may be performed by hardware and/or as computer instructions on a non-transient computer (or machine) readable storage medium.
In certain embodiments, and as shown herein in regard to FIG. 2, the ECM includes one or more modules structured to functionally execute the operations described herein. The description herein including the components of the ECM emphasizes the structural independence of the aspects of the ECM. and illustrates one grouping of operations and responsibilities of the ECM. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or as computer instructions on a non-transient computer readable storage medium, and modules may be distributed across various hardware or computer based components.
Example and non-limiting module implementation elements include sensor (e.g., sensor 110) providing any value determined herein, sensors providing any value that is a precursor to a value determined herein, datalink and/or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, and/or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to the module specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and/or digital control elements.
As mentioned above, many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.
Modules may also be implemented in machine-readable medium for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.
Indeed, a module of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. Where a module or portions of a module are implemented in machine-readable medium (or computer-readable medium), the computer readable program code may be stored and/or propagated on in one or more computer readable medium(s).
The computer readable medium may be a tangible computer readable storage medium storing the computer readable program code. The computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.
More specific examples of the computer readable medium may include but are not limited to a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), an optical storage device, a magnetic storage device, a holographic storage medium, a micromechanical storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, and/or store computer readable program code for use by and/or in connection with an instruction execution system, apparatus, or device.
The computer readable medium may also be a computer readable signal medium. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electrical, electro-magnetic, magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport computer readable program code for use by or in connection with an instruction execution system, apparatus, or device. Computer readable program code embodied on a computer readable signal medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, Radio Frequency (RF), or the like, or any suitable combination of the foregoing
In one embodiment, the computer readable medium may comprise a combination of one or more computer readable storage mediums and one or more computer readable signal mediums. For example, computer readable program code may be both propagated as an electro-magnetic signal through a fiber optic cable for execution by a processor and stored on RAM storage device for execution by the processor.
Computer readable program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone computer-readable package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
The program code may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

Claims

An apparatus, comprising:
an engine stop module (134) structured to receive a stop command (162), the stop command (162) providing an indication of an engine (105) transitioning to an off state;

an engine position module (135) structured to:
receive position data (161) indicative of a position of a crankshaft of the engine (105); and

determine a stop position of the crankshaft based on the position data (161) when the engine (105) is in the off state;

an engine restart module 136 structured to receive a restart command (163), the restart command (163) providing an indication of the engine (105) transitioning from the off state to an on state; and

an engine ignition module (139) structured to facilitate a restart of the engine (105) to the on state responsive to the restart command (163), wherein the engine ignition module (139) is structured to determine a first viable cylinder to begin combustion in based on the determined stop position of the crankshaft and a firing order for the engine (105), wherein the first viable cylinder is a cylinder immediately following a cylinder that would have experienced a next combustible event according to the firing order but for the engine (105) reaching the off state.
The apparatus of claim 1, wherein the position data (161) is indicative of a position of a crankshaft wheel (120) coupled to the crankshaft, wherein the position data (161) is indicative of a first rotation direction and a second rotation direction of the crankshaft wheel (120), wherein the second rotation direction is opposite the first rotation direction.
The apparatus of claim 2, wherein the engine position module (135) is structured to determine an initial stop position of the crankshaft wheel (120) based on an initial change in rotation direction following the engine stop module receiving the stop command (162), wherein the engine position module (135) is structured to determine the stop position of the crankshaft based on a number of first rotation oscillations and second rotation oscillations while the engine (105) is coming to the off state.
The apparatus of any preceding claim, further comprising an engine adjustment module (137), wherein the engine adjustment module (137) is structured to adjust a position of the piston in the first viable cylinder to facilitate a relatively faster engine restart.
The apparatus of claim 4, wherein the engine adjustment module (137) is structured to adjust the position of the piston based on a predefined amount of time while the engine (105) is in the off state, wherein the adjustment of the piston is closer to a bottom dead center position in the first viable cylinder; or
wherein the engine adjustment module (137) is structured to adjust the position of the piston based on at least one of a decrease in at least one of a temperature and a pressure in the first viable cylinder by more than a predefined amount, wherein the adjustment of the piston is closer to a bottom dead center position in the first viable cylinder.
The apparatus of claim 4, wherein the engine adjustment module (137) is structured to adjust the position of the piston based on a predicted decay in at least one of a temperature and a pressure in the first viable cylinder by more than a predefined amount, wherein the adjustment of the piston is closer to a bottom dead center position in the first viable cylinder.
A system, comprising:
the apparatus of claim 1;

an engine (105) having a crankshaft coupled to a crankshaft wheel (120), such that the crankshaft and crankshaft wheel (120) rotate in sync;

a sensor (110) structured to acquire position data (161) regarding a position of the crankshaft wheel (120); and

an engine control module (130) communicably coupled to the sensor (110), the engine control module (130) including the engine stop module (134), the engine position module (135), the engine restart module (136), and the engine ignition module (139), the engine control module (130) structured to:
receive, by the engine stop module (134), an engine stop command (162), the engine stop command (162) configured to shut down the engine (105);

receive, by the engine position module (135), the position data (161) from the sensor (110);

determine, by the engine position module (135), a stop position of the crankshaft wheel based on the position data (161) when the engine (105) is shut down;

receive, by the engine restart module (136), an indication of an engine restart;

determine, by the engine ignition module (139), a first viable cylinder to begin combustion in based on the determined stop position of the crankshaft wheel (120); and

provide a command to initiate combustion in the first viable cylinder to restart the engine (105).
The system of claim 7, wherein the sensor (110) is a bi-directional sensor such that the position data (161) is indicative of the crankshaft wheel (120) rotating in each of a first rotational direction and a second rotational direction, the second rotational direction opposite the first rotational direction; wherein optionally
the crankshaft wheel (120) includes a plurality of teeth (122).
The system of claim 8, wherein the engine control module (130) is structured to determine the stop position of the crankshaft wheel (120) by:
determining a tooth number of an initial stop position on the crankshaft wheel (120), wherein the initial stop position being where the position data (161) indicates that the crankshaft wheel (120) has changed rotation direction following receipt of the engine stop command (162);

counting a number of teeth that correspond with the first rotation direction;

counting a number of teeth that correspond with the second rotation direction; adding the number of teeth corresponding to the first rotation direction to the anchor tooth number to determine a forward tooth number; and

subtracting the number of teeth corresponding to the second rotation direction from the forward tooth number to determine the stop position of the crankshaft wheel (120).
The system of any of claims 7 to 9, wherein the first viable cylinder is based on a firing order for the engine (105),
wherein the first viable cylinder is based on a firing order for the engine (105), wherein the first viable cylinder is a cylinder immediately following a cylinder that would have experienced a next combustible event according to the firing order but for the engine (105) reaching the off state.
The system of any of claims 7 to 10, wherein the engine control module (130) is structured to adjust a position of a piston in the first viable cylinder based on at least one of a passage of a predefined amount of time while the engine is shut down and a decrease in at least one of a temperature and a pressure in the first viable cylinder by more than a predefined amount relative to at least one of an initial temperature and an initial pressure in the first viable cylinder when the stop command (162) was received.
The system of Claim 11, wherein the engine control module (130) is structured to adjust the piston towards bottom dead center in the first viable center based on the passage of the predefined amount of time or the decrease in at least one of the temperature and the pressure in the first viable cylinder by more than the predefined amount.
A method, comprising:
receiving, by an engine control module (130), an engine stop command (162) in a vehicle, the engine stop command (162) structured to shut down an engine (105) of the vehicle;

receiving, by the engine control module (130), position data (161) from a bi-directional sensor (110), the position data (161) indicative of a position of a crankshaft wheel (120);

determining, by the engine control module (130), a stop position of the crankshaft wheel (120) based on the position data (161) when the engine (105) is shut down;

determining, by the engine control module (130), a first viable cylinder of the engine (105) to restart combustion in based on the determined stop position of the crankshaft wheel wherein the first viable cylinder is based on a firing order for the engine (105), wherein:
the first viable cylinder is based on a firing order for the engine (105), wherein the first viable cylinder is a cylinder immediately following a cylinder that would have experienced a next combustible event according to the firing order but for the engine (105) reaching the off state; and

receiving, by the engine control module (130), an engine restart command (163), the engine restart command (163) structured to restart the engine (105) beginning with initiation of combustion in the first viable cylinder.
The method of claim 13, further comprising adjusting, by the engine control module (130), a position of the piston in the first viable cylinder based on at least one of a passage of a predefined amount of time while the engine (105) is shut down and a decrease in at least one of a temperature and a pressure in the first viable cylinder by more than a predefined amount relative to at least one of an initial temperature and an initial pressure in the first viable cylinder when the stop command (162) was received.