Engine Stop-Start Starter Assembly Position Control

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Solution Overview

Problem

Automatic engine restarts in stop-start systems can generate noise, vibration, and harshness (NVH) concerns due to the engine being restarted from unfavorable positions, particularly when the crankshaft needs to rotate through a large arc before firing.

Innovation Solution

A method and apparatus for controlled stopping of an internal combustion engine using a brushless electric starter assembly, which includes detecting the engine's rotational speed and position, energizing the starter to engage the engine at a predetermined stop position, applying torque to stop the engine at a target position, and confirming engagement with a time delay, thereby minimizing NVH during restarts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the engine is restarted automatically in stop-start mode, then fuel consumption is reduced, but noise, vibration, and harshness (NVH) increase due to unfavorable crankshaft positions

Engineering Contradiction:

Improvefuel consumptionVSAvoidnoise, vibration, and harshness (NVH)

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary action by stopping the engine at a predetermined target position (within +/−30 degrees of TDC) before restart occurs. This preliminary positioning ensures that when restart is needed, the crankshaft is already in an optimal position, eliminating the need for large arc rotation and thereby reducing NVH while maintaining fuel efficiency benefits of stop-start operation

Inventive Principle:

Principle #10Preliminary action

2Speed

If the starter assembly engages the engine without precise position control, then the engine can be restarted quickly, but the crankshaft must rotate through a large arc before firing, increasing NVH

Engineering Contradiction:

Improverestart speedVSAvoidnoise, vibration, and harshness (NVH)

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system employs feedback by continuously monitoring the engine's rotational position via a sensor and comparing it to the target stop position. This feedback loop allows the controller to determine when the crankshaft is within the predetermined range (+/−30 degrees of TDC) and to confirm when the target position is reached, enabling precise control that minimizes NVH while maintaining quick restart capability

Inventive Principle:

Principle #23Feedback

3Loss of time

If the starter assembly is engaged immediately without confirmation, then the stopping process is faster, but engagement timing may be inaccurate, affecting stopping precision

Engineering Contradiction:

Improvestopping timeVSAvoidstopping position precision

Core Design Contradiction:

Loss of timeVSManufacturing precision

Solution Approach 1:

The system applies beforehand cushioning by establishing a time delay after energizing the starter assembly to confirm engagement before applying full stopping torque. This cushioning approach ensures the pinion gear is fully engaged with the ring gear, preventing timing errors and ensuring precise stopping at the target position while maintaining efficient stopping speed

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables precise control over engine stopping and restarting, reducing noise, vibration, and harshness by aligning the crankshaft with the target stop position, ensuring smoother engine reactivation and improved vehicle comfort.

Implementation Method 1

The starter assembly may include a brushless electric motor, a solenoid, and a pinion gear. The brushless electric motor may be configured to spin the pinion gear

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The brushless electric motor may be configured to spin the pinion gear and the solenoid may be configured to shift the pinion gear

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnet

Implementation Method 3

The starter assembly may additionally include a housing and a spring arranged between the pinion gear and the housing. In such an embodiment, the spring may be configured to release the pinion gear from the ring gear when the solenoid is de-energized

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10677212B2Method and apparatus for controlled stopping of internal combustion engine

Publication Date: 2020.06.09 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method of controlled stopping an internal combustion engine having a stop-start mode and starter assembly includes detecting when the stop-start mode is active. The method also includes monitoring current rotational speed and position of the engine. The method additionally includes determining when the current rotational position is within a predetermined range of a target stop rotational position and the current rotational speed is less than a threshold rotational speed, and afterward energizing the starter assembly to engage the engine. The method also includes establishing a time delay following energizing the starter assembly to confirm engagement of the starter assembly with the engine. Furthermore, the method includes applying a torque by the starter assembly to stop the engine at the target stop position. A vehicle powertrain employing the engine equipped with the stop-start mode, the starter assembly, and an electronic controller configured to execute the method is also provided.