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EP-4359658-B1 - SYSTEM FOR AN INTERNAL COMBUSTION ENGINE WITH AN ELECTRIC TORQUE ASSIST

EP4359658B1EP 4359658 B1EP4359658 B1EP 4359658B1EP-4359658-B1

Inventors

  • RAMAN, UMASHANKAR
  • KUMAR, ASHOK

Dates

Publication Date
20260506
Application Date
20220622

Claims (8)

  1. A system for an internal combustion (IC) engine with an electric torque assist (300), wherein the system comprises: a crankshaft assembly (305) of the IC engine; a piston assembly that is connected with the crankshaft assembly (305) of the IC engine; an integrated starter generator (ISG) (312) that is connected to a side of the crankshaft assembly (305) of the IC engine using a shaft (320), wherein the ISG (312) operates in any of a motoring mode (M) or a generation mode (G); characterized in that , a sensing assembly (310) that is mounted internally or externally between the crankshaft assembly (305) and the ISG (312) of the IC engine, wherein the sensing assembly (310) provides a stream of pulses proportional to an instantaneous speed of the crankshaft assembly (305) and generates pulses with respect to the position of the piston assembly; a MOSFET bridge (330) that is connected to the ISG (312), wherein the MOSFET bridge (330) enables the motoring mode (M) or the generation mode (G) of the ISG (312); a MOSFET driver (335) that is connected to the MOSFET bridge (330), wherein the MOSFET driver (335) is configured to switch operations of the MOSFET bridge (330) during torque-assist to the motoring mode (M) or the generation mode (G); a battery (340) and a pulsar coil (316); and a control unit (325) comprising: a controller or a processor (405) that is configured to: determine the instantaneous speed of the crankshaft assembly (305) using the stream of pulses from the sensing assembly (310); compute the pulses from the sensing assembly (310) into one or more engine cycle phases; monitor the instantaneous speed of the crankshaft assembly (305) and speed shortfall in the IC engine ; determine a target value for the torque-assist by analysing the speed shortfall and the instantaneous speed of the crankshaft assembly (305), or detecting the position of piston assembly by the sensing assembly (310), when the instantaneous speed of the crankshaft assembly (305) is less than a predefined threshold speed value of the IC engine; and provide the torque assist to the ISG (312) by switching the MOSFET bridge (330) to the motoring mode (M) of the ISG (312) using the MOSFET driver (335) to maintain an optimum torque-assist throughout the one or more engine cycle phases.
  2. The system as claimed in claim 1, wherein the IC engine comprises a 2-stroke engine or 4-stroke engine.
  3. The system as claimed in claim 1, wherein the controller or the processor (405) is configured to switch the MOSFET bridge (330) to the generation mode (G) of the ISG (312) when the instantaneous speed of the crankshaft assembly (305) is greater than or equal to the predefined threshold speed value of the IC engine.
  4. The system as claimed in claim 1, wherein the one or more engine cycle phases for the 4-stroke engine comprises a suction stroke, a compression stroke, a power stroke, and an exhaust stroke, wherein the one or more engine cycle phases for the 2-stroke engine comprises a suction/compression stroke and a power/exhaust stroke.
  5. The system as claimed in claim 1, wherein the sensing assembly (310) is mounted externally to the ISG (312) of the IC engine to include one or more sensors, wherein the one or more sensors comprise magnetic pick-up coils, Hall-effect sensors, magneto-resistive element (MRE) sensors, and optical sensors.
  6. The system as claimed in claim 1, wherein the sensing assembly (310) is mounted internally to the ISG (312) of the IC engine to determine the stream of pulses, wherein the stream of pulses can be detected with the control unit (325) using any of back EMF measurement, zero-crossing detection, or current sensing (434).
  7. The system as claimed in claim 1, wherein the one or more engine cycle phases can be detected using the pulsar coil (316).
  8. A method for an internal combustion (IC) engine with electric torque assist (300) comprises: providing, using a sensing assembly (310), a stream of pulses proportional to an instantaneous speed of a crankshaft assembly (305) and a position of a piston assembly reaching a Top Dead Center (TDC) of the IC engine when it is running; determining, using a control unit (325), the instantaneous speed of the crankshaft assembly (305) using the stream of pulses from the sensing assembly (310); computing, using the control unit (325), the pulses from the sensing assembly (310) into one or more engine cycle phases comprising a suction stroke, a compression stroke, a power stroke, and an exhaust stroke; monitoring, using the control unit (325), the instantaneous speed of the crankshaft assembly (305) and speed shortfall in the IC engine; determining, using the control unit (325), a target value for the torque-assist by analysing the speed shortfall and the instantaneous speed of the crankshaft assembly (305), or detecting the position of piston assembly by the sensing assembly (310), when the instantaneous speed of the crankshaft assembly (305) is less than a pre-defined threshold speed value of the IC engine; and providing, using the control unit (325), the torque-assist to an ISG (312) by switching a MOSFET bridge (330) to a motoring mode (M) of the ISG (312) using a MOSFET driver (335) to maintain an optimum torque-assist throughout the one or more engine cycle phases; and switching, using the control unit (325), the ISG (312) in a generation mode using the MOSFET bridge (330) when the instantaneous speed of the crankshaft assembly (305) is greater than or equal to the predefined threshold speed value of the IC engine.

Description

BACKGROUND TECHNICAL FIELD The present subject matter is related to internal combustion (IC) engines in general, and in particular with an implementation of an electric torque assist in the IC engines to provide inertial compensation for reducing mass-based inertial components added to a 2 stroke or 4 strokes IC engines. Furthermore, the disclosed subject matter includes a method for providing electric-torque assist to overcome crankshaft speed variation over strokes during engine operation, thereby overcoming a speed variation problem caused by the engine's lower inertia at low and idle speeds. DESCRIPTION OF THE RELATED ART Conventionally, a 2-stroke or 4-stroke Internal Combustion (IC) engines have only one stroke of two strokes or four strokes, respectively, providing enough power to keep the IC engine running. The two strokes in the 2-stroke engine are referred to as a "compression stroke," when an air-fuel mixture is compressed, and a "power stroke," when an ignited compressed air-fuel mixture provides a large downward force to a piston assembly, providing power to the engine. The power impulse is thus generated during one of the two strokes, and the crankshaft rotates one revolution during the two strokes, with a 180-degree rotation in each stroke. In the 4-stroke engine, there are four strokes including a suction stroke, a compression stroke, a power stroke , and an exhaust stroke, where two strokes make a 360-degree rotation of the crankshaft, and the power stroke provides the power to the engine. In both types of the engines, the compression stroke energy demand is high in order to compress the air-fuel mixture to a high degree, allowing the mixture to ignite in a subsequent power stroke, with the power stroke beginning at a Top Dead Centre (TDC) and ending at a Bottom Dead Centre (BDC), covering a 180-degree rotation of the crankshaft during this power stroke. To ensure that the subsequent compression stroke can compress the air-fuel mixture, every internal combustion (IC) engine has an intertrial block made an integral part of the crankshaft or provided as a flywheel component attached to the crankshaft so that the energy needs of the compression stroke are met from the stored energy of the inertial block, with the energy of the inertial block augmented during the power stroke by the ignition of the air-fuel mixture. Any reduction in inertial block mass results in a large speed swing during the compression stroke, with this swing being more pronounced at low and idling speeds of the internal combustion (IC) engine. For instance, Fig. 1 illustrates an exemplary schematic view of an Internal Combustion (IC) engine assembly with an Integrated Starter Generator (ISG) 115 connected to a crankshaft and an inertial mass provision made as part of the crankshaft for speed optimization in conventional internal combustion (IC) engine according to the prior art. The Internal Combustion (IC) engine with the integrated starter generator (ISG) 115 is mounted on the crankshaft. The conventional system includes, in general, an internal combustion (IC) engine assembly 100 including a piston assembly 112 including a fuel-air mixture into a confined space 114 for ignition at a Top Dead Centre (TDC) position 125 during the upward stroke (i.e the compression stroke). A crankshaft assembly 105, which includes a necessary inertial mass attached for maintaining necessary rotational in the conventional internal combustion (IC) engine, is coupled to the integrated starter generator (ISG) 115 mounted on the crankshaft as illustrated in a shaft representation 116. The piston assembly 112 moves with every stroke between the Top Dead Centre (TDC) 125 and the Bottom Dead Centre (BDC) 120, and two such reciprocating strokes make one 360-degree rotational revolution of the crankshaft assembly 105. With the integrated starter generator (ISG) 115 connected to the crankshaft assembly 105, the integrated starter generator (ISG) 115 also makes one revolution during one revolution of the crankshaft assembly 105. US 2019/249617 A1 discloses a driveline and the use of an integrated electric starter-generator to assist with attenuation of driveline shuffle. Therefore, there is a need to address the aforementioned technical drawbacks and problems in a speed variation problem associated with the engine's lower inertia at low and idle speed operation of the engine. SUMMARY In view of the foregoing, an embodiment of the present invention provides a configuration in which the above problem of crankshaft speed variation due to reduced inertial mass is overcome by using an Integrated Starter Generator (ISG), specifically in the motoring mode (M) with torque assist during the appropriate stroke, thus meeting the speed shortfall in the crankshaft speed throughout the appropriate stroke of both 2-stroke and 4-stroke engines, during idling and low-speed operation. With lower inertial mass and overall engine weight, it is thus feasible to provide sp