GB2559742A

GB2559742A - A method of cranking an internal combustion engine of a motor vehicle

Info

Publication number: GB2559742A
Application number: GB1702442.3A
Authority: GB
Inventors: Frevert Nicolas; Schilder Boris; Schnorpfeil Stephan-Johannes; Eggert David
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2017-02-15
Filing date: 2017-02-15
Publication date: 2018-08-22
Also published as: GB201702442D0

Abstract

A method of restarting the engine 110 of a vehicle 90 when in motion, the engine being decoupled from the drive wheels 500. Parameters indicative of the required engine torque are used to determine the cranking torque to start the engine. A started motor 520 performs the cranking until the crankshaft 145 speed reaches a predetermined speed. The restart may be determined based on acceleration or braking demands. The restart time may be reduced by introducing fuel to the engine or coupling the drive wheels during cranking. The method helps to improve drivability of stop start coast (SSC) engines by delivering a dynamic response. Noise and vibration of the engine is also kept to an acceptable level. A computer program, computer program product, electromagnetic signal and motor vehicle which carry out the method are also disclosed.

Description

(71) Applicant(s):

GM Global Technology Operations LLC (Incorporated in USA - Delaware)

PO Box 300, 300 Renaissance Center, Detroit, 48265-3000, United States of America (56) Documents Cited:

WO 2016/181634 A1 US 20160245254 A1 US 20130296126 A1

US 20160327005 A1 US 20150266480 A1 US 20130296109 A1 (58) Field of Search:

INT CL B60W, F02N Other: EPODOC & WPI (72) Inventor(s):

Nicolas Frevert Boris Schilder

Stephan-Johannes Schnorpfeil David Eggert (74) Agent and/or Address for Service:

Adam Opel AG

Intellectual Property Patents, IPC:A0-02, 65423 RUsselsheim, Germany (54) Title of the Invention: A method of cranking an internal combustion engine of a motor vehicle Abstract Title: Method of cranking a stop start coasting engine (57) A method of restarting the engine 110 of a vehicle 90 when in motion, the engine being decoupled from the drive wheels 500. Parameters indicative of the required engine torque are used to determine the cranking torque to start the engine. A started motor 520 performs the cranking until the crankshaft 145 speed reaches a predetermined speed. The restart may be determined based on acceleration or braking demands. The restart time may be reduced by introducing fuel to the engine or coupling the drive wheels during cranking.

The method helps to improve drivability of stop start coast (SSC) engines by delivering a dynamic response. Noise and vibration of the engine is also kept to an acceptable level.

A computer program, computer program product, electromagnetic signal and motor vehicle which carry out the method are also disclosed.

535

446

520

2/2

FIG.4

A METHOD OF CRANKING AN INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE

TECHNICAL FIELD

The present disclosure relates to a method of cranking an internal combustion engine of a motor vehicle while the motor vehicle is moving and the internal combustion engine is decoupled from the drive wheels, as it may happen for example but not exclusively when a Stop/Start Coasting (SSC) vehicle exits a coasting phase.

BACKGROUND

In order to reduce fuel consumption and polluting emissions some SSC vehicles have been proposed in recent years whose internal combustion engine is automatically decupled from the drive wheels and switched off when, after an acceleration phase, the driver completely releases the accelerator pedal.

In this way, the SSC vehicles undergo a sailing coasting phase in which the vehicles continues to move under the effect of the inertia, without spending fuel and thus without generating polluting emissions.

During this sailing coasting phase, it may happen that the driver presses the accelerator pedal to increase the vehicle speed or the brake pedal to slow down and possibly bring the vehicle to a halt. In both these cases, the internal combustion engine is automatically cranked and coupled to the drive wheels in order to propel the vehicle or to perform a regenerative braking.

The internal combustion engine is generally cranked by means of a starter motor, namely an electric motor that rotates the crankshaft of the internal combustion engine up to a minimum rotational speed, above which the engine is able to continue running under its own power.

Before reaching this minimum rotational speed, small quantities of fuel may be supplied and ignited into the combustion chambers of the internal combustion engine, in order to support the starter motor in rotating the crankshaft and thus speed up the cranking phase of the internal combustion engine.

The torque delivered by the electric started and the fuel quantities injected during the engine cranking phase are generally design parameters, so that the time required by the internal combustion engine to complete the cranking phase is constant or almost constant in any conditions.

Such constant cranking time may however have an unfavourable impact on the drivability of the motor vehicle, because there may be circumstances in which the cranking time is too long for guaranteeing a prompt dynamic response of the motor vehicle and other circumstances in which the cranking time is too short for keeping the noises and the vibrations of the internal combustion engine within acceptable levels.

SUMMARY

In view of the above, an object of the present disclosure is that of providing a solution that allows to adjust the cranking phase of an internal combustion engine in response to different driving conditions, particularly in response to different maneuvers performed by the driver.

This and other objects are achieved by the embodiments of the solution having the features reported in the independent claims. The dependent claims delineate additional aspects of such embodiments.

In greater details, an embodiment of the present disclosure provides a method of cranking an internal combustion engine of a motor vehicle while the motor vehicle is moving and the internal combustion engine is decoupled from the drive wheels, said method comprising the steps of:

- measuring a value of a parameter indicative of an engine torque requested by a driver of the motor vehicle,

- determining a value of a cranking torque to be delivered to a crankshaft of the internal combustion engine on the basis of the measured value of said parameter,

- operating a starter motor coupled to the crankshaft to deliver the cranking torque value, until a crankshaft rotational speed reaches a predetermined value thereof.

Thanks to this solution the cranking torque delivered by the starter motor and thus the overall cranking time of the internal combustion engine can be appropriately adjusted in response to the driver’s torque request.

According to an embodiment of the disclosure, the parameter indicative of the engine torque requested by the driver may be a displacement of an accelerator pedal from a released position thereof and/or a variation rate of the accelerator pedal displacement over time.

This embodiment provides a reliable solution for determining that the driver is demanding a positive engine torque (i.e. a traction torque) to accelerate the motor vehicle.

According to an aspect of this embodiment, the cranking torque value may be increased as the measured value of the parameter increases.

In other words, the cranking torque value corresponding to a given value of the parameter, for example to a given displacement of the accelerator pedal from the released position and/or to a given variation rate of the accelerator pedal displacement, may be larger than the cranking torque value corresponding to smaller values of the same parameter, for example to smaller displacements of the accelerator pedal and/or to smaller variation rates of the accelerator pedal displacement.

Thanks to this aspect, the overall cranking time of the internal combustion engine is reduced when the driver is requesting a prompt and fast acceleration of the motor vehicle, for example because he wants to overtake another vehicle, and is increased when a prompt acceleration in not necessary, thereby reducing the electrical energy spent by the starter motor.

According to another aspect of this embodiment, the method may comprise the additional step of injecting and igniting a fuel quantity into the internal combustion engine, before the crankshaft rotational speed reaches the predetermined value thereof.

The injection and the ignition of this fuel quantity has the effect of supporting the starter motor in rotating the crankshaft, thereby speeding up the cranking phase of the internal combustion engine.

The fuel quantity to be injected and ignited into the internal combustion engine may be determined on the basis of the measured value of the parameter.

In this way the torque supplied by the combustion of this fuel quantity is adjusted according to the driver’s torque request.

In particular, the fuel quantity may be increased as the measured value of the parameter increases.

In other words, the fuel quantity corresponding to a given value of the parameter, for example to a given displacement of the accelerator pedal from the released position and/or to a given variation rate of the accelerator pedal displacement, may be larger than the fuel quantity value corresponding to smaller values of same parameter, for example to smaller displacements of the accelerator pedal and/or to smaller variation rates of the accelerator pedal displacement.

Thanks to this aspect, it is possible to increase the engine performance, when the driver is requesting a prompt and fast acceleration of the motor vehicle, for example because he wants to overtake another vehicle, whereas it is possible to reduce the vibrations, the noises and the polluting emissions (e.g. the CO2 emissions) when a prompt and fast acceleration is not necessary.

According to another embodiment of the invention, the parameter indicative of the engine torque requested by the driver may be a displacement of a brake pedal from a released position thereof and/or a variation rate of the brake pedal displacement over time.

This embodiment provides a reliable solution for determining that the driver is demanding a negative value of the engine torque (i.e. the braking torque) to decelerate the motor vehicle.

An aspect of this embodiment provides that the method may comprise the step of coupling the crankshaft to drive wheels before the crankshaft rotational speed reaches the predetermined value thereof, if the brake pedal displacement exceeds a predetermined threshold value thereof.

In this way, when the driver is performing a hard braking, the rotation of the drive wheel helps the starter motor is speeding up the crankshaft, thereby reducing the overall cranking time of the internal combustion engine.

Another aspect of this embodiment provides that no fuel injections are performed inside the internal combustion engine before the crankshaft rotational speed reaches the predetermined value thereof.

In this way no fuel is spent during the cranking phase, thereby saving money and reducing the polluting emissions (e.g. the CO2 emissions).

According to the present disclosure, the method can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of a computer program product comprising the computer program. The method can be also embodied as an electromagnetic signal, said signal being modulated to carry a sequence of data bits which represent a computer program to carry out all steps of the method.

Another embodiment of the solution provides a motor vehicle comprising an internal combustion engine, a starter motor coupled to a crankshaft of the internal combustion engine and an electronic control unit that, for cranking the internal combustion engine while the motor vehicle is moving and the internal combustion engine is decoupled from the drive wheels, is configured to:

- measure a value of a parameter indicative of an engine torque requested by a driver of the motor vehicle,

- determine a value of a cranking torque to be delivered to the crankshaft of the internal combustion engine on the basis of the measured value of said parameter,

- operate the starter motor coupled to the crankshaft to deliver the cranking torque value, until a crankshaft rotational speed reaches a predetermined value thereof.

This embodiment achieves basically the same effects of the method above, in particular that allowing an appropriate adjustment of the cranking torque delivered by the starter motor in response to the driver’s torque request.

The aspects of the solution described with reference to the method may be applied also to this embodiment. In particular, an aspect of the solution provides that the parameter indicative of the engine torque requested by the driver may be a displacement of an accelerator pedal from a released position thereof and/or a variation rate of the accelerator pedal displacement over time. The electronic control unit may be configured to increase the cranking torque value as the measured value of the parameter increases. The electronic control unit may be further configured to inject and ignite a fuel quantity into the internal combustion engine, before the crankshaft rotational speed reaches the predetermined value thereof. The electronic control unit may be configured to determine the fuel quantity to be injected and ignited into the internal combustion engine on the basis of the measured value of the parameter. In particular, the electronic control unit may be configured to increase the fuel quantity as the measured value of the parameter increases. Another aspect of the solution provides that the parameter indicative of the engine torque requested by the driver may be a displacement of a brake pedal from a released position thereof and/or a variation rate of the brake pedal displacement over time. The electronic control unit may be further configured to couple the crankshaft to drive wheels of the motor vehicle before the crankshaft rotational speed reaches the predetermined value thereof, if the brake pedal displacement exceeds a predetermined threshold value thereof. The electronic control unit may be also configure to perform no fuel injections into the internal combustion engine, before the crankshaft rotational speed reaches the predetermined value thereof.

Still another embodiment of the solution provides an apparatus for cranking an internal combustion engine of a motor vehicle while the motor vehicle is moving and the internal combustion engine is decoupled from the drive wheels, said apparatus comprising:

- means for measuring a value of a parameter indicative of an engine torque requested by a driver of the motor vehicle,

- means for determining a value of a cranking torque to be delivered to a crankshaft of the internal combustion engine on the basis of the measured value of said parameter,

- means for operating a starter motor coupled to the crankshaft to deliver the cranking torque value, until a crankshaft rotational speed reaches a predetermined value thereof.

Also this embodiment achieves basically the same effects of the method above, in particular that allowing an appropriate adjustment of the cranking torque delivered by the starter motor in response to the driver’s torque request.

The aspects of the solution described with reference to the method may be applied also to this embodiment. In particular, an aspect of the solution provides that the parameter indicative of the engine torque requested by the driver may be a displacement of an accelerator pedal from a released position thereof and/or a variation rate of the accelerator pedal displacement over time. The apparatus may comprise means for increasing the cranking torque value as the measured value of the parameter increases. The apparatus may further comprise means for injecting and igniting a fuel quantity into the internal combustion engine, before the crankshaft rotational speed reaches the predetermined value thereof. The apparatus may comprise means for determining the fuel quantity to be injected and ignited into the internal combustion engine on the basis of the measured value of the parameter. In particular, the apparatus may comprise means for increasing the fuel quantity as the measured value of the parameter increases. Another aspect of the solution provides that the parameter indicative of the engine torque requested by the driver may be a displacement of a brake pedal from a released position thereof and/or a variation rate of the brake pedal displacement over time. The apparatus may further comprise means for coupling the crankshaft to drive wheels of the motor vehicle before the crankshaft rotational speed reaches the predetermined value thereof, if the brake pedal displacement exceeds a predetermined threshold value thereof. The apparatus may further comprise means for performing no fuel injections into the internal combustion engine, before the crankshaft rotational speed reaches the predetermined value thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings.

Figure 1 schematically shows a moto vehicle.

Figure 2 shows an internal combustion engine of the motor vehicle according to the section A-A of figure 1.

Figure 3 is a flowchart representing a method of cranking the internal combustion engine when triggered by a depression of the accelerator pedal of the motor vehicle.

Figure 4 is a flowchart representing a method of cranking the internal combustion engine when triggered by a depression of the brake pedal of the motor vehicle.

DETAILED DESCRIPTION

Some embodiments may include a motor vehicle 90 comprising an automotive system 100, as shown in figures 1 and 2, that includes an internal combustion engine (ICE) 110. In this example, the ICE 110 is a spark-ignition engine (e.g. a gasoline engine). In other embodiments, the ICE 110 could be a compression-ignition engine (e.g. Diesel engine). The ICE 110 has an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150. A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gasses to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gasses from an exhaust manifold 225 that directs exhaust gasses from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gasses through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust gasses exit the turbine 250 and are directed into an exhaust system 270. The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gasses. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gasses in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gasses in the EGR system 300.

In order to move the motor vehicle 90, the crankshaft 145 of the ICE 110 is mechanically coupled to the drive wheels 500 of the motor vehicle 90 by means of a transmission 505, as shown in figure 2. The transmission 505 may be a manual transmission or an automatic transmission. The transmission 505 generally includes a gearbox 510 coupled to the drive wheels 500, for example via a driveline, and a clutch 515 coupled between the gearbox 510 and the crankshaft 145. The clutch 515 may be selectively moved in a closed position, where it actually engages the crankshaft 145 to the gearbox 510, or in an open position, where the crankshaft 145 is disengaged from the gearbox 510. The clutch 515 may be an electrically driven clutch, namely a clutch that is moved between the closed and the open position by an electric actuator.

The ICE 110 is further equipped with a starter motor 520 for cranking the engine. The starter motor 520 is coupled to the crankshaft 145 in a point comprised between the ICE 110 and the clutch 515. In particular, the starter motor 520 may part of a mild hybrid system which uses the starter motor 520 to contribute power to the crankshaft 145. For example, the starter motor 520 may be a Belt Alternator Starter (BAS) of a BAS hybrid system. The BAS is an electric machine which is coupled to the crankshaft 145 via a transmission belt 525 and which can operate as an electric motor, in order to crank the ICE 110 and provide power assist during acceleration of the motor vehicle 90, as well as an electric generator, in order to perform regenerative braking during decelerations. In other embodiments, the BAS system may be replaced by any other mild hybrid system that uses an electric motor coupled to the crankshaft 145.

The ICE 110 further comprises an accelerator pedal 530 which can be manually moved by a driver in different positions to regulate the power generated by the ICE 110, for example by regulating the position of the throttle valve 330. In particular, the accelerator pedal 530 is designed to generally stay in a released position, for example biased by a spring or other suitable devices, and can be displaced by the driver from the released position towards any intermediate position between the released position and a fully depressed position.

A brake pedal 535 is also present which can be manually moved by the driver in different positions to brake the motor vehicle 90. Also the brake pedal 535 is designed to generally stay in a released position, for example biased by a spring or other suitable devices, and can be displaced by the driver from the released position towards any intermediate position between the released position and a fully depressed position.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110. The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, an accelerator pedal position sensor 445, and a brake pedal position sensor 446. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, the cam phaser 155, the clutch 515 and the starter motor 520. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system 460, and send and receive signals to/from the interface bus. The memory system 460 may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analogue and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110.

The program stored in the memory system 460 is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a wireless connection to a laptop.

In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or nonpermanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an on-board computer, or any processing module that might be deployed in the vehicle.

The ECU 450 may be configured to implement a Stop/Start Coasting (SSC) strategy. While the motor vehicle 90 is actually moving (e.g. after an acceleration), the SSC strategy generally provides for the ECU 450 to open the clutch 515, thereby decoupling the crankshaft 145 from the drive wheels 500, and to switch off the ICE 110, if the driver completely releases both the accelerator pedal 530 and the brake pedal 535. In this way, the motor vehicles 90 undergoes a sailing coasting phase in which the motor vehicles 90 continues to move under the effect of the inertia, without spending fuel and thus without generating polluting emissions.

During this sailing coasting phase, the ECU 450 monitors the position of the accelerator pedal 530 and of the brake pedal 535 by means of the sensors 445 and 446. If the ECU 450 senses that the driver presses the accelerator pedal 530 or the brake pedal 535, the ECU 450 terminates the sailing coasting phase.

To terminate the sailing coasting phase, the ECU 450 perform a cranking phase of the ICE 110 and, once the engine cranking phase is complete, the ECU 450 closes the clutch 515 in order to coupie the crankshaft 145 to the drive wheel 500.

The engine cranking phase generally provides for the ECU 450 to increase the rotational speed of the crankshaft 145 up to a predetermined target value thereof. By way of example, this target value of the crankshaft rotational speed may be a minimum value above which the ICE 110 is able to continue running under its own power (i.e. only by means of fuel injections), or it may be the current rotational speed of the driven shaft of the clutch 515, namely the shaft which is directly connected to the gearbox 510, in order to reach the synchronism.

To achieve this effect, the ECU 450 may perform the steps indicated in the flow chart of figure 3, if the engine cranking phase is triggered by a depression of the accelerator pedal 530, or the steps indicated in the flow chart of figure 4, if the engine cranking phase is triggered by a depression of the brake pedal 535.

If the engine cranking phase is triggered by a depression of the accelerator pedal 530, the ECU 450 may be configured to measure a value A of the displacement of the accelerator pedal 530 from the released position (block S100). In other words, the ECU 450 measures the position that the accelerator pedal 530 reaches after being depressed by the driver. This displacement value may be measured by means of the position sensor 445 and may be expressed in terms of a percentage of the working stroke of the accelerator pedal 530 from the released position, which may correspond to 0% of the working stroke, to the fully depressed position, which may correspond to 100% of the working stroke.

The ECU 450 may be further configured to measure a variation rate G (gradient) of the accelerator pedal displacement over time (block S105). In other words, the ECU 450 measures the speed with which the accelerator pedal 530 has been depressed by the driver from the released position (when the motor vehicle was still in the coasting phase) to the position measured in step S100. This measurement may be made by the ECU 450 using the data coming from the position sensor 445 over time.

The displacement value A and the variation rate G are indicative of the positive torque (i.e. traction torque) that the driver is demanding to the automotive system 100 to accelerate the motor vehicle 90.

Based on the displacement value A and the variation rate G, the ECU 450 may be configured to determine a corresponding value Q of a cranking torque to be delivered to the crankshaft 145 for performing the cranking phase of the ICE 110 (block S110), and to operate the starter motor 520 to deliver the determined cranking torque value Q to the crankshaft 145 (block S115), until the rotational speed of the crankshaft 145 reaches the target value thereof.

Thanks to this approach, the cranking torque value Q provided by the starter motor 520 is not a constant design parameter but becomes a parameter that depends on the driver’s demand.

In particular, the cranking torque value Q may increase as the displacement value A and the variation rate G increase. In other words, the cranking torque value Q corresponding to a given displacement values A and to a given variation rate G may be larger than the cranking torque value Q corresponding to lower displacement values A and/or lower variation rates G.

In this way, the cranking phase of the internal combustion engine may be completed fast when the driver is requesting a prompt acceleration of the motor vehicle 90, for example because he wants to overtake another vehicle, whereas it may be completed in a longer time when a prompt acceleration in not demanded, thereby reducing the electrical energy spent by the starter motor 520.

From a practical point of view, the cranking torque value Q may be retrieved by the ECU 450 from a calibration map correlating the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement to a corresponding value Q of the cranking torque. In other embodiments, the ECU 450 may calculate the cranking torque value Q as a function of the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement, using a predetermined mathematical equation.

When triggered by a depression of the accelerator pedal 530, the cranking phase of the ICE 110 may further provide for the ECU 450 to inject and ignite a quantity F of fuel into the combustion chambers 150, for example once per engine cycle, while the starter motor 520 is delivering the cranking torque value Q and thus before the rotational speed of the crankshaft 145 has reached the target value thereof (block S120). The injection of the fuel quantity F may be operated by actuating the fuel injectors 160, whereas the ignition of the fuel quantity F may be either spontaneous (if the ICE 110 is a compressionignition engine) or caused by actuating spark plugs located in the engine cylinders 140 (if the ICE 110 is a spark-ignition engine).

In this way, the combustion of this fuel quantity F in the combustion chambers 150 has the effect of supporting the starter motor 520 in rotating the crankshaft 120, thereby speeding up the cranking phase of the ICE 110.

Even the fuel quantity F may be a parameter that depends on the driver’s demand. By way of example, the ECU 450 may be configured to determine the fuel quantity F on the basis of the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement.

In particular, the fuel quantity F may be increased as the displacement value A and/or the variation rate G increase. In other words, the fuel quantity F corresponding to a given displacement values A and a given variation rate G may be larger than the fuel quantity F corresponding to lower displacement values A and/or lower variation rates G.

In this way, the engine performance may be increased, when the driver is requesting a prompt acceleration of the motor vehicle 90, while reducing the vibrations, the noises and the polluting emissions (e.g. the CO2 emissions) when a prompt acceleration is not necessary.

From a practical point of view, the fuel quantity F may be retrieved by the ECU 450 from another calibration map correlating the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement to a corresponding fuel quantity F. In other embodiments, the ECU 450 may calculate the fuel quantity F as a function of the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement, using a predetermined mathematical equation.

Thanks to the approach described above, it is possible for the ECU 450 to adjust the cranking torque Q delivered by the starter motor 520 and/or the fuel quantity F injected and ignited into the combustion chambers 150 during the engine cranking phase in response to different scenarios.

A first scenario may be encountered when the driver presses the accelerator pedal 530 slightly (soft tip-in), for example when the accelerator pedal displacement value A is equal to or less than 30% of the working stroke. In this case, the corresponding values of the cranking torque Q and of the fuel quantity F may be calibrated in order to optimize the engine cranking phase in terms of reduction of polluting emissions (e.g. CO2 emissions) and/or in term of reduction of noises and vibrations, thereby guaranteeing the best comfort and fuel savings.

A second scenario may be encountered when the driver presses the accelerator pedal

530 aggressively (aggressive tip-in), for example when the accelerator pedal displacement value A is larger than 30% of the working stroke and optionally the variation rate G of the accelerator pedal displacement is high. In this case, the corresponding values of the cranking torque Q and of the fuel quantity F may be calibrated in order to complete the engine cranking phase in the fastest possible way, thereby obtaining the lowest response delay.

It should be observed that, notwithstanding the procedure described above provides for determining the cranking torque Q and/or the fuel quantity F on the basis of both the accelerator pedal displacement value A and the variation rate G of the accelerator pedal displacement, according to other embodiments, the procedure could determine the cranking torque Q and/or the fuel quantity F only on the basis of the accelerator pedal displacement value A or the variation rate G of the accelerator pedal 530, or on the basis of any other parameter indicative of the torque that the driver is actually requesting for propelling the motor vehicle.

On the other hand, if the engine cranking phase is triggered by a depression of the brake pedal 535 (see fig. 4), the ECU 450 may be similarly configured to measure a value B of the displacement of the brake pedal 535 from the released position (block S200). In other words, the ECU 450 measures the position that the brake pedal 535 reaches after being depressed by the driver. This displacement value may be measured by means of the position sensor 446 and may be expressed in terms of a percentage of the working stroke of the brake pedal 535 from the released position, which may correspond to 0% of the working stroke, to the fully depressed position, which may correspond to 100% of the working stroke.

The ECU 450 may be further configured to measure a variation rate V (gradient) of the brake pedal position over time (block S205). In other words, the ECU 450 measures the speed with which the brake pedal 535 has been depressed by the driver from the released position (when the motor vehicle was still in the coasting phase) to the position measured in step S200. This measurement may be made by the ECU 450 using the data coming from the position sensor 446 over time.

The displacement value B and the variation rate V are indicative of a negative torque (i.e. braking torque) that the driver is demanding to the automotive system 100 to decelerate the motor vehicle 90.

Based on the displacement value B and optionally on the variation rate V, the ECU 450 may be configured to determine a corresponding value Q of a cranking torque to be delivered to the crankshaft 145 for performing the cranking phase of the ICE 110 (block S210), and to operate the starter motor 520 to deliver the determined cranking torque value Q to the crankshaft 145 (block S215), until the rotational speed of the crankshaft 145 reaches the target value thereof.

Even in this case, the cranking torque value Q provided by the starter motor 520 is thus not a constant design parameter but becomes a parameter that depends on the driver’s demand.

In particular, the cranking torque value Q may increase as the displacement value B and/or the variation rate V increase. In other words, the cranking torque value Q corresponding to a given displacement values B and a given variation rate V may be larger than the cranking torque value Q corresponding to lower displacement values B and/or lower variation rates V.

In this way, the cranking phase of the internal combustion engine may be completed faster when the driver is demanding a fast deceleration of the motor vehicle 90, whereas it may be completed in a longer time when a fast deceleration in not demanded, thereby reducing the electrical energy spent by the starter motor 520.

From a practical point of view, the cranking torque value Q may be retrieved by the ECU 450 from another calibration map correlating the brake pedal displacement value B and the variation rate V of the brake pedal displacement to a corresponding value Q of the requested engine torque. In other embodiments, the ECU 450 may calculate the cranking torque value Q as a function of the brake pedal displacement value A and the variation rate G of the brake pedal displacement, using a predetermined mathematical equation.

Since the driver is requesting a negative (braking) torque, it is however not necessary in this case that the engine cranking phase is completed very fast. For this reason, the procedure may provide that, when the brake pedal 535 has been depressed, no fuel injections are performed into the combustion chambers 150 of the ICE 110 during the engine cranking phase, namely until the rotational speed of the crankshaft 145 reaches the target value thereof, thereby reducing fuel consumption and polluting emissions (e.g. CO2 emissions). In addition, the values of the cranking torque Q corresponding to different displacement values B and/or different the variation rates V may be calibrated in order to optimize the engine cranking phase in terms of reduction of noises and vibration, rather than in term of engine performance.

When triggered by a depression of the brake pedal 535, the cranking phase of the ICE 110 may also provide for the ECU 450 to check if displacement of the brake pedal 535 exceeds a predetermined value B’ thereof (block S220). The value B’ may represent the displacement of the brake pedal 535 above which the driver is performing an hard braking of the motor vehicle 90 and below which the driver is performing an soft braking. The value B’ may be a calibration value and may be for example equal to a 30% of the working stroke of the brake pedal 535.

If the measured value B of the brake pedal displacement exceeds the threshold value B’ (i.e. a hard braking is identified), the cranking phase may provide for the ECU 450 to close the clutch 515 and thus to couple the crankshaft 145 to the drive wheels 500, before the crankshaft rotational speed reaches the target value thereof (block S225).

In this way, the rotation of the drive wheels 500 contributes to accelerate the crankshaft 145, thereby allowing a faster completion of the engine cranking phase and/or allowing a reduction of the cranking torque Q provided by the starter motor 520, thereby saving electrical energy.

It should be observed that, notwithstanding the procedure described above provides for determining the cranking torque Q on the basis of both the brake pedal displacement value B and the variation rate V of the brake pedal displacement, according to other embodiments, the procedure could determine the cranking torque Q only on the basis of the brake pedal displacement value B or the variation rate V of the brake pedal, or on the basis of any other parameter indicative of the torque that the driver is actually requesting for braking the motor vehicle.

It should also be observed that, notwithstanding the procedures above have been described in connection with a sailing coasting phase of the motor vehicle 90, the same procedures could be implemented for cranking the ICE 110 whenever the motor vehicle 90 is moving with the ICE 110 switched off and the crankshaft 145 decoupled from the drive wheels 500.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCES motor vehicle

100 automotive system 110 internal combustion engine

120 engine block

125 cylinder

130 cylinder head

135 camshaft

140 piston

145 crankshaft

150 combustion chamber

155 cam phaser

160 fuel injector

170 fuel rail

180 fuel pump

190 fuel source

200 intake manifold

205 air intake duct

210 intake port

215 valves

220 exhaust port

225 exhaust manifold

230 turbocharger

240 compressor

250 turbine

260 intercooler

270 exhaust system

275 exhaust pipe

280 aftertreatment devices

290 VGT actuator

300 exhaust gas recirculation system 310 EGR cooler

320 EGR valve

330 throttle body

340 mass airflow and temperature sensor

350 manifold pressure and temperature sensor 360 combustion pressure sensor

380 coolant and oil temperature and level sensors

400 fuel rail pressure sensor

410 cam position sensor

420 crank position sensor

430 exhaust pressure and temperature sensors

440 EGR temperature sensor

445 accelerator pedal position sensor

446 brake pedal position sensor

450 ECU

460 memory system

500 drive wheels

505 transmission

510 gearbox

515 clutch

520 starter motor

525 transmission belt

530 accelerator pedal

535 brake pedal

S100 block

S105 block

S110 block

S115 block

S120 block

S200 block

S205 block

S210 block

S215 block

S220 block

S225 block

A accelerator pedal displacement value

B brake pedal displacement value

B' threshold value of the brake pedal displacement

G variation rate of the accelerator pedal V variation rate of the brake pedal

Claims

1. A method of cranking an internal combustion engine (110) of a motor vehicle (90) while the motor vehicle (90) is moving and the internal combustion engine (110) is decoupled from drive wheels (500), said method comprising the steps of:

- measuring a value of a parameter indicative of an engine torque requested by a driver of the motor vehicle (90),

- determining a value of a cranking torque to be delivered to a crankshaft (145) of the internal combustion engine (110) on the basis of the measured value of said parameter,

- operating a starter motor (520) coupled to the crankshaft (145) to deliver the cranking torque value, until a crankshaft rotational speed reaches a predetermined value thereof.

2. A method according to claim 1, wherein the parameter indicative of the engine torque requested by the driver is a displacement of an accelerator pedal (530) from a released position thereof and/or a variation rate of the accelerator pedal displacement over time.

3. A method according to claim 2, comprising the step of increasing the cranking torque value as the measured value of the parameter increases.

4. A method according to claim 2 or 3, comprising the step of injecting and igniting a quantity of fuel into the internal combustion engine (110), before the crankshaft rotational speed reaches the predetermined value thereof.

5. A method according to claim 4, wherein the fuel quantity is determined on the basis of the measured value of the parameter.

6. A method according to claim 5, comprising the step of increasing the fuel quantity as the measured value of the parameter increases.

7. A method according to any of the preceding claims, wherein the parameter indicative of the engine torque requested by the driver may be a displacement of a brake pedal (535) from a released position thereof and/or a variation rate of the brake pedal displacement over time.

8. A method according to claim 7, comprising the step of coupling the crankshaft (145) to the drive wheels (500) before the crankshaft rotational speed reaches the predetermined value thereof, if the brake pedal displacement exceeds a predetermined threshold value thereof.

9. A method according to claim 7 or 8, wherein no fuel injections are performed inside the internal combustion engine (110) before the crankshaft rotational speed reaches the predetermined value thereof.

10. A computer program comprising a program-code for carrying out all the steps of the method according to any of the preceding claims.

11. A computer program product comprising the computer program of claim 10.

12. An electromagnetic signal modulated to carry a sequence of data bits which represent the computer program of claim 10.

13. A motor vehicle (90) comprising an internal combustion engine (110), a starter motor (520) coupled to a crankshaft (145) of the internal combustion engine and an electronic control unit (450) that, for cranking the internal combustion engine (110) while the motor vehicle (90) is moving and the internal combustion engine (110) is decoupled from the drive wheels (500), is configured to:

- measure a value of a parameter indicative of an engine torque requested by a driver of the motor vehicle (90),

- determine a value of a cranking torque to be delivered to the crankshaft (145) of the internal combustion engine (110) on the basis of the measured value of said parameter,

- operate the starter motor (520) coupled to the crankshaft (145) to deliver the cranking torque value, until a crankshaft rotational speed reaches a predeter mined value thereof.

Intellectual

Property

Office

Application No: GB 1702442.3 Examiner: Nicholas Wigley