Engine Controller for Motorized Crankcase Scavenging at Shutdown

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Solution Overview

Problem

Conventional internal combustion engines struggle to effectively scavenge the crankcase when the engine is not running, leading to condensation and moisture accumulation in the lubricating oil due to incomplete warm-up during frequent start-stop cycles.

Innovation Solution

A controller for the engine that includes a forced-induction device with a compressor wheel and motor, a flow rate adjusting valve, and scavenging control to draw fresh air into the crankcase through a first passage and into the intake passage via a second passage, even when the engine is off, using motoring control to rotate the crankshaft during high intake pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional scavenging using intake passage pressure during engine operation is used, then scavenging is effective during engine running, but scavenging cannot be performed when the engine is not running

Engineering Contradiction:

Improvescavenging effectivenessVSAvoidscavenging availability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically switches between two scavenging modes: during engine operation, it uses natural intake passage pressure differential scavenging; during engine shutdown, it activates motor-driven forced induction scavenging. This dynamic adaptation resolves the contradiction by making the scavenging system effective in both running and non-running states.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The forced induction device with motor acts as an intermediary mechanism that enables scavenging during engine shutdown. When the engine is not running, the motor drives the compressor to generate pressure differential, replacing the natural engine-driven pressure differential and enabling continued scavenging functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the engine is repeatedly stopped and started before warm-up completion, then operational flexibility is improved, but condensation and moisture accumulate in the crankcase

Engineering Contradiction:

Improveoperational flexibilityVSAvoidcondensation and moisture accumulation

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The controller performs scavenging operations during engine shutdown periods as a preliminary action before the next engine start. This proactive scavenging removes moisture and condensation from the crankcase before they can accumulate harmful levels, enabling the engine to tolerate repeated start-stop cycles without moisture-related damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains continuous crankcase protection by performing scavenging both during engine operation and during shutdown periods. This continuous action ensures that moisture is consistently removed from the crankcase regardless of engine state, preventing accumulation even during frequent start-stop cycles.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If scavenging is performed during engine shutdown using motor-driven forced induction, then crankcase scavenging capability is improved, but power consumption increases

Engineering Contradiction:

Improvescavenging capability during shutdownVSAvoidmotor power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous motor operation, the system uses periodic scavenging cycles during engine shutdown. The controller activates the motor for specific durations to perform scavenging, then stops the motor, repeating this cycle as needed. This periodic action achieves effective crankcase clearing while minimizing overall power consumption compared to continuous operation.

Inventive Principle:

Principle #19Periodic action

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

Effectively scavenges the crankcase to prevent condensation and moisture accumulation, reducing power consumption and discomfort from noise by optimizing scavenging operations based on engine temperature and pressure conditions.

Implementation Method 1

a forced-induction device that drives the compressor wheel using the motor

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

By utilizing the pressure within the intake passage generated during engine operation, blow-by gas within the crankcase is drawn into the intake passage for scavenging

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS12460590B2Controller for internal combustion engine

Publication Date: 2025.11.04 TOYOTA JIDOSHA KK

AI summary

A controller is configured to control an internal combustion engine. The internal combustion engine includes an intake passage, a motor, a forced-induction device, a flow rate adjusting valve, a crankcase, and first and second passages connected to the crankcase. The forced-induction device uses the motor to drive a compressor wheel provided in the intake passage. The flow rate adjusting valve is provided downstream of the compressor wheel in the intake passage. The controller includes processing circuitry configured to execute scavenging control that drives the motor with the flow rate adjusting valve closed in a case where engine shutdown is performed.