EP4291768A1

EP4291768A1 - A method for starting an ic engine of a vehicle and system thereof

Info

Publication number: EP4291768A1
Application number: EP22704013.6A
Authority: EP
Inventors: Manickam Murugesan; Palani Shunmugasundaram; Balaji Vaidyanathan; Praveenkumar Arunkumar; Naveen Natarajan Krishnakumar
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2021-02-12
Filing date: 2022-02-07
Publication date: 2023-12-20
Also published as: CN114922760A; WO2022172287A1

Abstract

The present invention is directed to a method for starting an Internal Combustion (IC) engine (110) connected to a crankshaft (120) coupled with an ISG (130), the method comprising: receiving (304) a start signal by an ECU (140); communicating (306) the start signal to an ISG controller (150) communicatively coupled with the ISG; cranking (307) the crankshaft in a reverse direction by the ISG in response to a first signal, corresponding to the start signal, from the ISG controller; monitoring (308) position of the crankshaft by the ECU; delaying (309) injection and ignition of air fuel mixture inside the IC engine by the ECU during reverse direction of rotation of the crankshaft; and rotating (310) the crankshaft in a forward direction by the ISG in response to a second signal from the ISG controller thereby starting the IC engine.

Description

A Method for Starting an 1C Engine of a Vehicle and System Thereof

FIELD OF THE INVENTION

[001] The present invention relates a method for starting an internal combustion engine of a vehicle and system thereof.

BACKGROUND OF THE INVENTION [002] Vehicles utilizing a power source, such as an Internal Combustion (IC) engine, to generate power are typically equipped with a transmission system to transmit power generated by the power source to one or more wheels of the vehicle. In order to start the IC engine, a crankshaft of the IC engine is rotated. There are several known methods for rotating the crankshaft of the IC engine through various means, for example using an integrated starter generator (ISG) system.

[003] In general, the ISG system includes an ISG machine which includes a stator and a rotor connected to the crankshaft of the IC engine. The ISG system further includes an ISG controller which is operatively connected to the ISG machine. The ISG controller controls the ISG machine, for example by causing the ISG machine to work as engine starter or as a generator.

[004] While working as the engine starter, the ISG system rotates the crankshaft firstly in a reverse direction to acquire a desired momentum and thereafter in a forward direction. In general, when the crank shaft rotates, air fuel mixture is injected inside the IC engine. However, ignition takes place only during forward rotation. Accordingly, air fuel mixture injected during reverse rotation will add up with the air fuel mixture injected during forward rotation. As a result, combustion of the fuel does not happen completely and therefore, higher hydrocarbon emissions are emitted. As such, it is generally desired that injection of air fuel mixture and ignition of same should be triggered only during forward rotation of the crankshaft.

[005] To achieve the above, additional injection inhibiting means are installed in the existing engine control systems. These inhibiting means inhibit the fuel injection when the crankshaft rotates in the reverse direction. Therefore, whenever the crankshaft rotates in the reverse direction, both injection and ignition are disabled. Other engine control systems disable the starter switch input during reverse rotation of the crankshaft. [006] One of the major drawbacks associated with the existing engine control systems is that the crank position sensor processes the signal corresponding to the reverse rotation and starts engine synchronization. Once the completion of reverse rotation takes place, the engine control unit (ECU) schedules pre-injection. Due to processing of the reverse rotation of the crankshaft there is a mismatch in number of teeth (of the rotor) between gaps, thereby resulting in engine synchronization failure, which disables subsequent injection and ignition cycle. Since there is no ignition event to ignite the pre injected fuel, the fuel is emitted out as hydrocarbon emission. Now the ISG machine rotates the crankshaft in forward direction, which initiates resynchronization and rescheduling of injection and ignition. This resynchronization delays the engine start which increases the hydrocarbon emission and electrical load on the vehicle. [007] Thus, there is a need in the art for a method and a system for starting an internal combustion engine in a vehicle which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION

[008] In one aspect, the present invention is directed to a method for starting an Internal Combustion (1C) engine connected to a crankshaft coupled with an Integrated Starter Generator. The method comprises the steps of receiving a start signal by an Engine Control Unit, communicating the start signal to an Integrated Starter Generator controller communicatively coupled with the Integrated Starter Generator. Thereafter, the crankshaft is cranked in a reverse direction by the Integrated Starter Generator in response to a first signal, corresponding to the start signal, from the Integrated Starter Generator controller, followed by monitoring position of the crankshaft by the Engine Control Unit. The Engine Control Unit is configured to delay injection and ignition of air fuel mixture inside the 1C engine during reverse direction of rotation of the crankshaft, and rotate the crankshaft in a forward direction by the Integrated Starter Generator in response to a second signal from the Integrated Starter Generator controller thereby starting the 1C engine.

[009] In an embodiment of the invention, the Engine Control Unit continuously communicates the start signal to the Integrated Starter Generator controller for a predetermined time. The predetermined time is in between 1.5 seconds to 5 seconds. [010] In another embodiment of the invention, a crank position sensor in the IC engine continuously monitors the position of the crankshaft, said crank position sensor being coupled to the Engine Control Unit. A crank position signal received by the Engine Control Unit from the crank position sensor indicates any one of the forward direction of rotation of the crankshaft or the reverse direction of rotation of the crankshaft. The Engine Control Unit delays the injection and ignition of air fuel mixture inside the IC engine when it receives the crank position signal indicating the reverse direction of rotation of the crankshaft.

[011] In yet another embodiment of the invention, the Integrated Starter Generator controller generates the second signal in response to the Engine Control Unit communicating the start signal to the Integrated Starter Generator controller for the predetermined time. During rotation of the crankshaft in the forward direction the Engine Control Unit is configured to process the crank position signal indicating the forward direction of rotation of the crankshaft.

[012] In still another embodiment of the invention, starting the IC engine comprises scheduling injection and ignition of air fuel mixture based on position of the crankshaft during rotation in forward direction, determining by the Engine Control Unit whether the crankshaft rotates at a speed greater than a threshold engine start rotation speed, and entering by the Integrated Starter Generator controller in a generator mode if the crankshaft rotates at a speed greater than the threshold engine start rotation speed.. [013] In another aspect, the present invention is directed to starting system of an

Internal Combustion (IC) engine. The IC engine is connected to a crankshaft coupled with an integrated starter generator ISG, the starting system of the IC engine comprising an Engine Control Unit ECU, an ISG controller coupled with the ISG and the ECU, and a crank position sensor coupled with the ECU. The ECU is configured to receive a start signal, communicate the start signal to the ISG controller. The ISG cranks the crankshaft in a reverse direction in response to a first signal, corresponding to the start signal, received from the ISG controller. The system is configured to receive signal from the crank position sensor and monitor the position of the crankshaft followed by delaying of the injection and ignition of the air fuel mixture inside the IC engine during reverse rotation of the crankshaft. The ISG rotates the crankshaft in a forward direction after the delay, thereby starting the IC engine.

BRIEF DESCRIPTION OF THE DRAWINGS

[014] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 illustrates a block diagram of a system for starting an internal combustion (IC) engine in accordance with an embodiment of the present invention.

Figure 2 illustrates a block diagram of engine management system (EMS) showing an engine control unit (ECU) in accordance with an embodiment of the present invention.

Figure 3 illustrates a schematic of Integrated Starter Generator (ISG) system in accordance with an embodiment of the present invention.

Figure 4 illustrates a method for starting an internal combustion (IC) engine in accordance with an embodiment of the present invention.

Figure 5 illustrates the delay in injection and ignition of air fuel mixture during reverse rotation of the crankshaft in accordance with the method of Figure 4. Figure 6 illustrates a state-of-the-art method with injection and ignition of air fuel mixture during reverse rotation of the crankshaft.

DETAILED DESCRIPTION OF THE INVENTION

[015] The present invention relates to a method for starting an Internal Combustion (IC) engine and a system thereof.

[016] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. In the ensuing exemplary embodiments, the vehicle is a two wheeled vehicle. However, it is contemplated that the disclosure in the present invention may be applied to any automobile capable of accommodating the present subject matter without defeating the spirit of the present invention.

[017] Figure 1 illustrates a block diagram of a system 100 for starting an internal combustion (IC) engine 110 in accordance with an embodiment of the present invention. The IC engine 110 is connected to a crankshaft 120 coupled with an Integrated Starter Generator (ISG) 130. The system 100 has an Engine Control Unit 140, an ISG controller 150 coupled with the ISG 130 and the Engine Control Unit (ECU) 140, and a crank position sensor 160 coupled with the ECU 140.

[018] Figure 2 illustrates a block diagram of the engine management system (EMS) showing the engine control unit or ECU 140. The ECU 140 is coupled with a plurality of sensors, such as but not limited to, a throttle position sensor 170, a manifold pressure sensor 180, an intake air temperature sensor 190, an engine temperature sensor 200, a crank position sensor 160, and a lambda sensor 210. Further, a plurality of actuators are also coupled to the ECU 140, each of the actuators are actuated by the ECU 140 upon receiving input from the plurality of sensors described herein below.

[019] The throttle position sensor 170 measures a throttle opening percentage. The ECU 140 is configured to process the throttle opening percentage and detect an engine load and optimize the fuel quantity and ignition timing.

[020] The manifold pressure sensor 180 is configured to measure manifold absolute pressure. The ECU 140 is configured to process information and detect the engine load. The manifold pressure sensor 180 can also be used to detect the changes in altitude. The ECU 140 is configured to optimize the fuel quantity and ignition timing based on output from the manifold pressure sensor 180. [021] The intake air temperature sensor 190 is configured to measure an intake air temperature. The ECU 140 is configured to optimize the fuel quantity and ignition timing based on the inputs from the intake air temperature sensor 190.

[022] The engine temperature sensor 200 measures an engine block temperature based on which the ECU 140 is configured to optimize the fuel quantity and ignition timing.

[023] The crank position sensor 160 is configured to measure the position and rotational speed of the crankshaft 120. The ECU 140 is configured to optimize injection and ignition timing based on output from the crank position sensor 160. The crank position sensor 160 is discussed in detail in the description that follows.

[024] The lambda sensor 210 is configured to measure a residual oxygen content of the exhaust gases in an exhaust of the vehicle and send the feedback to ECU 140, thereby operating the IC engine 110 closer to stoichiometric air fuel ratio (i.e. lambda = 1 ). [025] The plurality of actuators coupled with the ECU 140 has different functions. For instance, an injector 220 is configured to inject a desired quantity of fuel to a combustion chamber. The idle air control valve 230 is a bypass valve configured to provide sufficient air for the IC engine 110 to idle. The cannister purge valve 240 is configured to purge the fuel vapors stored in a canister to an intake system, thereby reducing evaporative emission. The ignition coil 250 is configured to provide spark at the desired time with sufficient energy so that combustion of air-fuel mixture occurs in the combustion chamber. The electronic secondary air injection valve 260 is configured to allow for unburnt hydrocarbons exiting the combustion chamber to get oxidized in an exhaust passage. The lambda sensor heater 270 is configured to control the duty cycle of lambda heater and maintain internal resistance of the lambda sensor 210 close to nominal resistance.

[026] In the present context, “pre-drive process” refers to the normal functioning of the plurality of sensors and plurality of actuators, as confirmed by the ECU 140. Said otherwise, since the plurality of sensors and the plurality of actuators are coupled to the

ECU 140, the pre-drive process confirms that their functioning is normal and that none of them reports a malfunction or error.

[027] Referring to Figure 3, the functioning of a typical ISG system is illustrated. The ISG system includes the ISG controller 150 and the ISG 130. The ISG controller 150 is coupled to the ISG 130 which is configured to crank the crankshaft 120 upon receiving input from the ECU 140. An electric start switch, also referred as a user-operable input switch 280, is configured to instruct the ECU 140 to further instruct the ISG controller 150 to crank the crankshaft 120. The ISG controller 150 is configured to send the direction of rotation information to the ECU 140, for example by means of controller area network (CAN) or hardwired. The ECU 140 is further configured to receive Idle

Stop Start switch status 340 from a display screen or speedometer 310 of the vehicle, based on input received from Idle Stop Start switch 290.

[028] The ECU 140 and the ISG controller 150 are configured to communicate with each other as shown in Figure 3. In an embodiment, the ECU 140 is configured to communicate EMS start status 320 with the ISG controller 150. In another embodiment, the ISG controller 150 is configured to communicate with the ECU 140, for instance, malfunction or error 330 in ISG 130, ISG status 330, user-operable input switch 280 status 330, and the likes. [029] Referring to Figure 4, in step 301 , a user (interchangeably referred to as rider) actuates an ignition key of the vehicle. The actuation of the ignition key powers the ECU 140.

[030] In step 302, the ECU 140 is configured to check whether the pre-drive process has been completed. If the pre-drive process is incomplete and some of the plurality of sensors and/or the plurality of actuators are yet to report normal functioning, the ECU 140 waits until the same is concluded. This is shown in step 303.

[031] In an embodiment, if at least one of the plurality of sensors and/or plurality of actuators is malfunctioning or erroneous, the ECU 140 is configured to receive a corresponding input and inform the user of the same by way of an indication on the display screen or speedometer 310 of the vehicle. Consequently, the ECU 140 does not perform any of the further steps described in Figure 4 and therefore, the vehicle is not started.

[032] Upon receiving satisfactory input during the pre-drive process, in step 304, the ECU 140 is configured to receive a start signal in response to the user-operable input switch 280 being pressed. The user-operable input switch 280 is located on the vehicle, preferably on the handlebar.

[033] In case the user-operable input switch 280 is not in the pressed condition yet, the ECU 140 is configured to wait for the start signal to be received, as shown in step 305. [034] In step 306, when the electric start switch is in the pressed condition and the

ECU 140 has received the start signal, the ECU 140 is configured to continuously communicate the start signal to the ISG controller 150 for a predetermined time. In an embodiment, the predetermined time ranges in between 1.5 seconds to 5 seconds.

[035] In an embodiment, the communication between various controllers (such as but not limited to ECU 140, ISG controller 150 and the likes), sensors (incudes the plurality of sensors), actuators (includes the plurality of actuators, ISG 130, crankshaft 120, and the likes), and amongst themselves, is preferably carried out by means of CAN or hardwired.

[036] As shown in step 307, the ISG 130 is configured to crank the crankshaft 120 in a reverse direction in response to a first signal received from the ISG controller 150. In an embodiment, the ISG controller 150 is configured to generate the first signal in response to the ECU 140 communicating the start signal to the ISG controller 150 for the predetermined time.

[037] In step 308, the position of the crankshaft is monitored by the ECU 140. This is done by means of the crank position sensor 160 in the IC engine 110. The crank position sensor 160 is configured to continuously monitor the position of the crankshaft 120 and generate a crank position signal which is received by the ECU 140. The crank position signal is configured to indicate the forward rotation of the crankshaft 120 or the reverse rotation of the crankshaft 120, as is the case. [038] When the crank position signal indicates the reverse rotation of the crankshaft

120, the injection and ignition of air fuel mixture inside the IC engine 110 is delayed by the ECU 140. As shown in step 309, delaying the injection and ignition of air fuel mixture is due to the ECU 140 not communicating with the ISG controller 150 upon receiving the crank position signal indicating the reverse rotation of the crankshaft 120. [039] Advantageously, the crank position signal during reverse rotation of the crankshaft 120 is not processed and the IC engine 110 synchronization activity (i.e. injection and ignition of air fuel mixture) gets delayed. Since the ECU 140 does not process and ignores the crank position signal during reverse rotation, there is a delay in synchronization which not only results in less hydrocarbon emission but reduces the engine start time. Further, since the ECU 140 does not have to process the crank position signal, the electrical load on the vehicle is also reduced. Consequently, resulting in improved drivability of the vehicle.

[040] In an embodiment, the ISG controller 150 is configured to generate a second signal in response to the ECU 140 communicating the start signal to the ISG controller 150 for the predetermined time. As show in step 310, the forward rotation of the crankshaft 120 results in starting the IC engine 110. Said otherwise, the crank position signal indicating the forward rotation of the crankshaft 120 results in starting the IC engine 110.

[041] Unlike the reverse rotation, the ECU 140 is configured to process the crank position signal indicating the forward rotation of the crankshaft 120. Thus, resulting in the IC engine 110 synchronization activity being initiated (refer step 310a). Said otherwise, the injection and ignition of air fuel mixture inside the IC engine 110 takes place.

[042] The starting of the IC engine 110, as depicted through steps 310a to 310c, comprises scheduling injection and ignition of air fuel mixture based on position of the crankshaft 120 during forward rotation; determining by the ECU 140 whether the crankshaft 120 rotates at a speed greater than a threshold engine start rotation speed; and entering by the ISG controller 150 in a generator mode if the crankshaft 120 rotates at a speed greater than the threshold engine start rotation speed. [043] As shown in step 310b, if the crankshaft 120 rotation speed (determined by engine RPM sensor) is more than (or equal to) the threshold engine start rotation speed (or predetermined threshold engine RPM), the ISG controller 150 turns into generator mode and starts charging the battery 300, i.e. IC engine 110 has started. This is shown in step 310c. [044] In an embodiment, the threshold engine start rotation speed is 700 RPM to 1000 RPM. In case the crankshaft 120 rotation speed is less than the threshold engine start rotation speed, the step 310b is continuously repeated.

[045] In another aspect, the system 100 of the present invention as illustrated in Figure 1 is capable of performing the method as described herein. In this regard, the ECU 140 is configured to: receive a start signal and communicate the start signal to the ISG controller 150. The ISG 130 cranks the crankshaft 120 in a reverse direction in response to a first signal, corresponding to the start signal, received from the ISG controller 150. The ECU 140 is configured to receive signal from the crank position sensor 160 and monitor position of the crankshaft 120, and delay injection and ignition of air fuel mixture inside the IC engine 110 during reverse rotation of the crankshaft 120. The ISG 130 rotates the crankshaft 120 in a forward direction after the delay thereby starting the IC engine 110.

[046] Referring to Figure 5, the curves depicted by 401 , 402, 403, 404, 405 and 406 refer to engine speed, crank position sensor (160) output, ignition, injection, engine synchronization status and status bit indicating direction of rotation, respectively, for the present invention. Similarly, in Figure 6 the curves depicted by 501, 502, 503, 504, 505 and 506 refer to engine speed, crank position sensor 160 output, ignition, injection, engine synchronization status and status bit indicating direction of rotation, respectively, for the state of the art method.

[047] The advantages of the present invention are further evident by comparing Figure 5 and Figure 6. As shown in Figure 5, the data collected during IC engine starting, wherein the processing of crank position signal is delayed by the ECU 140. The status bit indicating direction of rotation information, 401 , is set to one during reverse rotation. At this time, the crank position signal, 402, is not processed by the ECU 140 which is also observed in engine speed, 401. Once the crankshaft rotates in the forward direction (as evident at value zero in 401), both crank position signal, 402, and IC engine synchronization activity, 405, is carried out by the ECU 140.

[048] The corresponding data in Figure 6 which represents the state-of-the-art method shows the IC engine synchronization, 505, and ECU 140 processing the crank position signal, 502, during reverse rotation of the crankshaft. As discussed herein, this results in increased engine start time and electrical load on the vehicle.

[049] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

CLAIMS:

1. A method for starting an Internal Combustion (IC) engine (110), the IC engine (110) connected to a crankshaft (120) coupled with an Integrated Starter Generator (130), the method comprising the steps of: receiving (304) a start signal by an Engine Control Unit (140); communicating (306) the start signal to an Integrated Starter Generator controller (150) communicatively coupled with the Integrated Starter Generator (130); cranking (307) the crankshaft (120) in a reverse direction by the Integrated Starter Generator (130) in response to a first signal, corresponding to the start signal, from the Integrated Starter Generator controller (150); monitoring (308) position of the crankshaft (120) by the Engine Control Unit (140); delaying (309) injection and ignition of air fuel mixture inside the IC engine (110) by the Engine Control Unit (140) during reverse direction of rotation of the crankshaft (120); and rotating (310) the crankshaft (120) in a forward direction by the Integrated Starter Generator (130) in response to a second signal from the Integrated Starter Generator controller (150) thereby starting the IC engine (110).

2. The method as claimed in claim 1, wherein the Engine Control Unit (140) continuously communicates the start signal to the Integrated Starter Generator controller (150) for a predetermined time.

3. The method as claimed in claim 2, wherein the predetermined time is in between 1.5 seconds to 5 seconds.

4. The method as claimed in claim 1, wherein a crank position sensor (160) in the IC engine (110) continuously monitors the position of the crankshaft (120), said crank position sensor (160) being coupled to the Engine Control Unit (140). 5. The method as claimed in claim 4, wherein a crank position signal received by the

Engine Control Unit (140) from the crank position sensor (160) indicates any one of the forward direction of rotation of the crankshaft (120) or the reverse direction of rotation of the crankshaft (120). 6. The method as claimed in claim 4 or 5, wherein the Engine Control Unit (140) delays the injection and ignition of air fuel mixture inside the IC engine (110) when it receives the crank position signal indicating the reverse direction of rotation of the crankshaft (120). 7. The method as claimed in claim 3, wherein the Integrated Starter Generator controller (150) generates the second signal in response to the Engine Control Unit (140) communicating the start signal to the Integrated Starter Generator controller (150) for the predetermined time. 8. The method as claimed in claim 4 or 5, wherein during rotation of the crankshaft

(120) in the forward direction the Engine Control Unit (140) is configured to process the crank position signal indicating the forward direction of rotation of the crankshaft (120). 9. The method as claimed in claim 1 or 9, wherein starting (310) the IC engine (110) comprises: scheduling (310a) injection and ignition of air fuel mixture based on position of the crankshaft (120) during rotation in forward direction; determining (310b) by the Engine Control Unit (140) whether the crankshaft (120) rotates at a speed greater than a threshold engine start rotation speed; and entering (310c) by the Integrated Starter Generator controller (150) in a generator mode if the crankshaft (120) rotates at a speed greater than the threshold engine start rotation speed.

10. A system (100) for starting an Internal Combustion (IC) engine (110), the IC engine (110) connected to a crankshaft (120) coupled with an integrated starter generator (130), the system (100) comprising: an Engine Control Unit (140); an integrated starter generator controller (150) coupled with the integrated starter generator (130) and the Engine Control Unit (140); and a crank position sensor (160) coupled with the Engine Control Unit (140); wherein the Engine Control Unit (140) is configured to: receive a start signal; communicate the start signal to the integrated starter generator controller (150), the integrated starter generator (130) cranks the crankshaft (120) in a reverse direction in response to a first signal, corresponding to the start signal, received from the integrated starter generator controller (150); receive signal from the crank position sensor (160) and monitors position of the crankshaft (120); and delay injection and ignition of air fuel mixture inside the IC engine (110) during reverse direction of rotation of the crankshaft (120), the integrated starter generator (130) rotates the crankshaft (120) in a forward direction after the 5 delay thereby starting the IC engine (110).