Four-Wheel-Drive Yaw Control via Independent Rear Coupling Torque

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Solution Overview

Problem

Conventional control apparatuses for four-wheel-drive vehicles generate operating sounds and discomfort due to solenoid valve operations during braking, causing vibrations in the brake pedal and ineffective yaw movement suppression.

Innovation Solution

A control apparatus that independently adjusts coupling torques between rear wheels using coupling devices, generating a yaw moment to counteract vehicle yaw without controlling solenoid valves, thereby suppressing yaw movement and reducing brake pedal vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solenoid valve control is used for yaw movement suppression during braking, then yaw movement can be suppressed, but operating sounds and brake pedal vibrations are generated causing driver discomfort

Engineering Contradiction:

Improveyaw movement suppression effectivenessVSAvoiddriver discomfort from operating sounds and vibrations

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and eliminates the solenoid valve control mechanism from the braking system. Instead of using solenoid valves to control braking pressure for yaw suppression, the patent uses the existing friction characteristics of the brake pads and discs to generate the necessary yaw moment, thereby removing the source of operating sounds and vibrations while maintaining yaw suppression effectiveness

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the electromagnetic control system (solenoid valves) with a passive mechanical system that utilizes the natural friction characteristics of the brake components. By adjusting the brake pad material properties and contact surfaces, the system achieves yaw suppression through mechanical friction rather than active electromagnetic valve control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If solenoid valve opening and closing is performed during braking control, then braking force can be adjusted, but hydraulic pressure changes cause brake pedal vibrations

Engineering Contradiction:

Improvebraking force control capabilityVSAvoidbrake pedal vibrations

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention removes the solenoid valve control mechanism that causes hydraulic pressure fluctuations and subsequent brake pedal vibrations. By relying on the inherent friction characteristics of the brake system, continuous and smooth braking force adjustment is achieved without the need for rapid valve opening and closing operations

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of actively controlling braking force through solenoid valve operations that cause pressure changes, the invention inverts the approach by utilizing the passive friction characteristics of the brake components. The system allows the friction interface to naturally regulate braking force, eliminating the vibration-causing active control mechanism

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If conventional braking control is used for yaw suppression, then yaw moment can be generated, but solenoid valve operations produce operating sounds

Engineering Contradiction:

Improveyaw moment generation capabilityVSAvoidoperating sounds from solenoid valve

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention extracts the solenoid valve component from the yaw suppression mechanism. By using the friction characteristics of the brake pads and discs, the system generates the necessary yaw moment without any moving valves or electromagnetic actuators, thereby eliminating operating sounds completely

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The brake system performs yaw suppression using its own inherent friction characteristics without requiring external control components. The friction interface between brake pads and discs naturally generates the yaw moment needed for vehicle stability, making the system self-sufficient and free from solenoid valve operations

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10562513B2Control apparatus for four-wheel-drive vehicle

Publication Date: 2020.02.18 TOYOTA JIDOSHA KK

AI summary

A control apparatus for a four-wheel-drive vehicle is configured to determine whether or not a degree of a yaw movement for deflecting the vehicle to a left or right side is larger than a predetermined first degree. When the degree of the yaw movement is larger than the first degree, the control apparatus increases a coupling torque of a coupling device corresponding to a rear wheel at the same side as a direction of the yaw movement to a predetermined first torque value, and maintains at zero a coupling torque of a coupling device corresponding to a rear wheel at an opposite side to the direction of the yaw movement.