Motorcycle Gearshift Torque Synchronization to Prevent Shift Shock

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Solution Overview

Problem

Current gear shifting methods in two-wheelers, such as motorcycles with manual transmissions, result in speed drops towards idle speed when the clutch is disengaged, requiring double-clutching, which prolongs shifting processes, causes switching shocks, and affects driving safety and comfort.

Innovation Solution

A gearshift assistant that uses a sensor unit to detect gear changes and vehicle speed, allowing the engine control to pre-control torque loss and synchronize clutch input and output speeds, enabling gear changes without clutch engagement, thereby reducing wear and improving shifting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the clutch is disengaged during gear shifting, then the gear change can be executed, but the engine speed drops towards idle speed causing shifting delays and switching shocks

Engineering Contradiction:
Improvegear shifting operationVSAvoidshifting time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The system performs preliminary actions by detecting the gear change event before the speed drop occurs, calculating the target engine speed based on the new gear ratio and vehicle speed, and preparing the torque adjustment in advance. This allows the engine speed to be rapidly adjusted back to the appropriate level without waiting for the natural speed drop to complete, thereby reducing overall shifting time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors engine speed, vehicle speed, and gear position, and uses this feedback to dynamically adjust the torque output. When a gear change is detected, the control unit calculates the speed discrepancy and applies corrective torque adjustments to bring the engine speed back to the target value, preventing both excessive speed drops and overshooting, thus reducing shifting time and eliminating shocks.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the clutch is disengaged during gear shifting, then the gear change can be executed, but switching shocks occur affecting driving comfort

Engineering Contradiction:
Improvegear shifting operationVSAvoidswitching shocks
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The control system continuously monitors engine speed and compares it against the target speed calculated from vehicle speed and gear ratio. When a gear change is detected, the system applies torque adjustments based on the speed discrepancy, dynamically correcting the engine speed to match the drivetrain speed. This feedback control prevents sudden speed mismatches that cause switching shocks, ensuring smooth transitions and improving driving comfort.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If the clutch is frequently operated for gear changes, then gear shifting can be achieved, but clutch wear increases

Engineering Contradiction:
Improvegear shifting operationVSAvoidclutch wear
Core Design Contradiction:
Ease of operationVSLoss of substance

Solution Approach 1:

The system uses the engine's own torque output and control capabilities to manage the gear transition process. By detecting gear changes and automatically adjusting torque to synchronize speeds, the system enables smooth gear shifts without requiring clutch engagement. The engine essentially services its own speed synchronization needs, eliminating the need for clutch operation and preventing wear.

Inventive Principle:
Principle #25Self-service

4Device complexity

If the engine speed is not controlled during gear changes, then the shifting process is simpler, but shifting jolts occur reducing riding safety and comfort

Engineering Contradiction:
Improvecontrol system complexityVSAvoidriding safety
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control system monitors engine speed, vehicle speed, and gear position in real-time, and uses this feedback to calculate and apply appropriate torque adjustments. When a gear change is detected, the system dynamically adjusts the engine torque to ensure the engine speed matches the drivetrain speed, preventing jolts and maintaining riding safety. The feedback loop continuously refines the torque control to achieve smooth transitions.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4251897B1Method for shift change for a two-wheeled vehicle
Publication Date: 2024.08.28 ROBERT BOSCH GMBH
  • EP4251897B1 patent drawingFigure 1
  • EP4251897B1 patent drawingFigure 2a~2b

AI summary

The present invention relates to a method for shift change for a two-wheeled vehicle, comprising at least the following steps: actuating a clutch of a two-wheeled vehicle, in particular a motorcycle, pre-controlling a loss torque of an internal combustion engine when opening the clutch, detecting a gear change by means of a sensor unit, transmitting a sensor signal to a motor controller, detecting a longitudinal speed of the vehicle, calculating the rotational speed at the clutch output as a function of the longitudinal speed of the vehicle and the drive train transmission ratio appropriate to the gear.