# US 11,441,526 B1 · Engine crank system and method

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- Number: US 11,441,526 B1
- Document ID: US11441526B1
- Status: Granted
- Kind: B1
- Application number: 17/397,026
- Filed: 2021-08-09
- Granted: 2022-09-13
- Earliest claimed: 2021-08-09
- Assignees: GM Global Technology Operations LLC
- Applicants: GM Global Technology Operations LLC
- Inventors: Pranjal Sharma; Chandra S. Namuduri; Suresh Gopalakrishnan
- Web page: https://patentgrep.com/patent/US11441526B1

## CPC

- F02N 11/006: {using a plurality of electric motors}
- F02B 67/06: driven by means of chains, belts, or like endless members
- F02N 11/04: the motors being associated with current generators
- F02N 11/0851: {characterised by means for controlling the engagement or disengagement between engine and starter, e.g. meshing of pinion and engine gear}
- F02N 19/005: {Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation}
- F02N 11/0814: {comprising means for controlling automatic idle-start-stop}
- F02N 15/04: the gearing including disengaging toothed gears
- F02N 15/08: the gearing being of friction type
- F02N 2200/021: Engine crank angle
- Y02T 10/40: Engine management systems
- F02N: STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Internal combustion engine cranking is carried out including with a limited overlapping of cranking with a starter motor and a starter/generator during at least the initial compression stroke during a cranking cycle.

## Claims

### Claim 1

A cranking system for an internal combustion engine, comprising:
a first electric machine rotatably coupled to a crankshaft of the engine;
a second electric machine rotatably coupled to the crankshaft of the engine; and
a controller executing an engine cranking cycle, comprising:
causing the first electric machine to crank the engine beginning from a stopped engine state and ending at a crankshaft angle substantially corresponding to a top dead center combustion position of a first piston undergoing a first compression stroke; and
causing the second electric machine to crank the engine beginning at a crankshaft angle subsequent to a bottom dead center intake position of the first piston undergoing the first compression stroke.

### Claim 2 (depends on 1)

The cranking system of claim 1, wherein the first electric machine is selectively rotatably coupled to the crankshaft of the engine.

### Claim 3 (depends on 1)

The cranking system of claim 1, wherein the first electric machine comprises a starter motor unit.

### Claim 4 (depends on 1)

The cranking system of claim 1, wherein the second electric machine comprises a starter/generator unit.

### Claim 5 (depends on 1)

The cranking system of claim 1, wherein the first electric machine is rotatably coupled to the crankshaft of the engine through a pinion gear of the first electric machine meshing with a ring gear coupled to a flywheel coupled to the crankshaft.

### Claim 6 (depends on 1)

The cranking system of claim 1, wherein the second electric machine is rotatably coupled to the crankshaft of the engine through a belt drive arrangement comprising a first pulley coupled to the second electric machine, a second pulley coupled to the crankshaft, and a belt coupled between the first pulley and the second pulley.

### Claim 7 (depends on 1)

The cranking system of claim 1, wherein the controller executing an engine cranking cycle further comprises causing the first electric machine to crank the engine beginning at a crankshaft angle during at least one subsequent compression stroke and ending at a crankshaft angle substantially corresponding to the end of the at least one subsequent compression stroke.

### Claim 8

A cranking system, comprising:
an internal combustion engine including a crankshaft, a flywheel coupled to the crankshaft and a ring gear coupled to the flywheel at a perimeter thereof;
a starter motor unit including a pinion gear rotatably coupled to an electric motor, the pinion gear being controllably engageable to the ring gear and the electric motor being controllably energizable to cause rotation of the pinion gear;
a starter/generator unit rotatably coupled to the crankshaft; and
a controller:
causing the pinion gear to engage with the ring gear and energizing the electric motor to crank the engine beginning from a stopped engine state and ending at a crankshaft angle substantially corresponding to a top dead center combustion position of a first piston undergoing a compression stroke; and
causing the starter/generator unit to crank the engine beginning at a crankshaft angle subsequent to a bottom dead center intake position of the first piston undergoing the compression stroke.

### Claim 9 (depends on 8)

The cranking system of claim 8, wherein causing the pinion gear to engage with the ring gear occurs while the engine is coasting down to the stopped engine state.

### Claim 10 (depends on 9)

The cranking system of claim 9, wherein causing the pinion gear to engage with the ring gear occurs while the engine is below a predetermined crankshaft speed target.

### Claim 11 (depends on 8)

The cranking system of claim 8, wherein the starter/generator unit comprises a field coil, and further comprising the controller causing pre-fluxing of the field coil while the electric motor is energized and prior to the starter/generator unit cranking the engine.

### Claim 12 (depends on 8)

The cranking system of claim 8, further comprising a rotation sensor sensing rotation of the crankshaft, wherein the rotation sensor provides crankshaft angle information to the controller.

### Claim 13 (depends on 8)

The cranking system of claim 8, further comprising a rotation sensor sensing rotation of the starter/generator unit which is synchronized to rotation of the crankshaft, wherein the rotation sensor provides crankshaft angle information to the controller.

### Claim 14 (depends on 8)

The cranking system of claim 8, further comprising the controller causing the starter motor unit to crank the engine beginning at a crankshaft angle during at least one subsequent compression stroke and ending at a crankshaft angle substantially corresponding to the end of the at least one subsequent compression stroke.

### Claim 15

A method of performing an engine cranking cycle, comprising:
cranking the engine with a starter motor during an initial cranking period beginning from a stopped engine state and ending at a crankshaft angle substantially corresponding to the end of a first compression stroke of a first piston to undergo a compression stroke; and
cranking the engine with a starter/generator beginning no later than at a crankshaft angle during the first compression stroke and continuing until the engine crank cycle ends.

### Claim 16 (depends on 15)

The method of performing the engine cranking cycle of claim 15, wherein cranking the engine with the starter/generator begins from the stopped engine state.

### Claim 17 (depends on 15)

The method of performing the engine cranking cycle of claim 15, wherein cranking the engine with the starter/generator begins during the first compression stroke.

### Claim 18 (depends on 15)

The method of performing the engine cranking cycle of claim 15, further comprising cranking the engine with the starter motor beginning at a crankshaft angle during at least one subsequent compression stroke and ending at a crankshaft angle substantially corresponding to the end of the at least one subsequent compression stroke.

### Claim 19 (depends on 15)

The method of performing the engine cranking cycle of claim 15, further comprising pre-fluxing a field coil of the starter/generator during the initial cranking period until cranking the engine with the starter/generator begins.

### Claim 20 (depends on 15)

The method of performing the engine cranking cycle of claim 15, further comprising engaging a pinion gear of the starter motor to a ring gear of a flywheel coupled to the crankshaft while the engine is coasting down to the stopped engine state.