Straddled Vehicle Hill Start Brake Pressure Control

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Solution Overview

Problem

Conventional hill start assist brake devices for straddled vehicles often fail to provide a smooth start, leading to nonsmoothness and instability when starting on slopes, as they do not accurately follow the driver's intention and are affected by variations in braking capacity due to environmental and state-dependent factors.

Innovation Solution

A control device that actuates the brake device without driver input, controlling brake pressure to decrease in sync with the braking force, ensuring a stable and smooth start by managing the difference between braking capacity and force, and includes features like pre-stop brake pressure setting and adaptive brake pressure control to enhance stability and reduce nonsmoothness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the brake device is actuated without driver input to maintain braking force for hill start, then the vehicle stability on slopes is improved, but the start smoothness deteriorates due to sudden brake pressure changes

Engineering Contradiction:
Improvevehicle stability on slopeVSAvoidstart smoothness
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The brake pressure control unit dynamically adjusts brake pressure based on driving force changes. When driving force increases during start, the system automatically decreases brake pressure proportionally, creating a smooth transition that maintains vehicle stability while avoiding sudden pressure changes that would cause nonsmoothness.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system continuously monitors driving force and uses this feedback to adjust brake pressure in real-time. The brake pressure control unit receives driving force information and automatically modulates brake pressure to follow the decrease in braking force, ensuring smooth start characteristics while maintaining hill start assist functionality.

Inventive Principle:
Principle #23Feedback

2Reliability

If brake pressure is maintained high to ensure braking capacity, then the ability to prevent rollback is improved, but the driver feels nonsmoothness during start

Engineering Contradiction:
Improverollback prevention capabilityVSAvoidnonsmoothness sensation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically balances braking capacity and smoothness by making brake pressure variable rather than fixed. As driving force increases during start, brake pressure automatically decreases to follow the braking force reduction, maintaining sufficient braking capacity to prevent rollback while eliminating the harmful nonsmoothness sensation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system changes the brake pressure parameter in response to driving force changes. By adjusting brake pressure to match the decrease in braking force, the system maintains the physical parameter (braking capacity) needed for rollback prevention while changing another parameter (actual brake pressure applied) to eliminate nonsmoothness.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3321142B1Control device for straddled vehicle, and straddled vehicle
Publication Date: 2020.03.25 YAMAHA MOTOR CO LTD
  • EP3321142B1 patent drawingFigure 1
  • EP3321142B1 patent drawingFigure 2(A)~2(C)
  • EP3321142B1 patent drawingFigure 3

AI summary

An object of the present teaching is to provide a control device for straddled vehicle that aids in stability of the straddled vehicle at a time of starting on a slope, etc., and that enables a smooth start with suppression of nonsmoothness felt by a driver. The present teaching provides a control device for straddled vehicle, the control device including: a brake control unit configured to actuate a brake device of the straddled vehicle when a driver's brake operation is deactivated and the brake operation is not performed while the straddled vehicle is stopped; and a brake pressure control unit configured to control a brake pressure of the brake device such that the brake pressure of the brake device decreases while following a decrease in a braking force of the brake device in the course of the braking force becoming zero from a state where the brake device is actuated without the brake operation performed at a time of starting the straddled vehicle.