Vehicle Power Unit Shift Drum Cogging Torque Positioning
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Solution Overview
Problem
Existing vehicle power units have a large size and complex structure due to the need for multiple parts and mechanisms, such as speed reduction gear mechanisms and stopper mechanisms, which increase costs and hinder quick and smooth gear changes with electric motors.
Innovation Solution
A vehicle power unit with a direct current electric motor producing pulsating cogging torque and a speed reduction gear train with multiple stages, allowing for effective braking and positioning of the shift drum without an intermittent feed mechanism, reducing the number of parts and complexity, and enabling quicker and smoother gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If speed reduction gear mechanism and stopper mechanism are added to enable effective braking and positioning of the shift drum, then gear positioning precision is improved, but device complexity increases and transmission apparatus size enlarges
Solution Approach 1:
The shift drum utilizes its own cogging torque to achieve braking and positioning functions. The uneven cam surface on the shift drum creates positional detents that automatically hold the drum at specific angular positions without requiring external stopper mechanisms. This self-service approach eliminates complex braking and positioning systems while maintaining precise gear positioning.
Solution Approach 2:
The invention extracts and eliminates unnecessary components from the transmission actuating mechanism. By removing the speed reduction gear mechanism and stopper mechanism, the system achieves gear positioning using only the shift drum, shift motor, and master arm. This extraction of unnecessary parts reduces device complexity while maintaining functionality.
2Measurement precision
If intermittent feed mechanism and stopper mechanism are disposed on the right end of the shift spindle while speed reduction gear mechanism is on the left end, then gear positioning is achieved, but transmission apparatus size enlarges in leftward and rightward directions
Solution Approach 1:
The invention merges the positioning and braking functions into the shift drum itself through the uneven cam surface design. This consolidation eliminates the need for separate speed reduction gear mechanisms and stopper mechanisms at both ends of the shift spindle, thereby reducing the transverse size of the transmission apparatus while maintaining precise gear positioning capability.
3Productivity
If multiple mechanisms are used to ensure quick and smooth gear changes with electric motor, then gear changing speed is improved, but manufacturing cost increases
Solution Approach 1:
The shift drum's uneven cam surface provides automatic positioning at each gear position, eliminating the need for complex control mechanisms. The cogging torque naturally decelerates and positions the drum at desired positions, reducing manufacturing cost while maintaining quick and smooth gear changing performance.
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 results in a smaller, less costly transmission apparatus that can perform quick and smooth gear changes without noise, eliminating the need for a soundproof structure and reducing the vehicle's size and weight, while maintaining effective gear positioning.
Implementation Method 1
a direct current motor that produces a pulsating cogging torque having a maximum value ranging from 0.04 to 0.07 Nm
Data Source
AI summary
A vehicle power unit has a transmission apparatus including a transmission, and a transmission actuating mechanism including a speed reduction gear train having multiple speed reduction stages for transmitting power from a drive gear on a drive shaft of a shift motor to a driven gear on a drum turning shaft of a shift drum. The speed reduction gear train has a speed reduction ratio ranging from 23 to 45, and the shift motor is a DC electric motor that produces a pulsating cogging torque having a maximum value ranging from 0.04 to 0.07 Nm. The vehicle power unit enables the transmission actuating mechanism to be made up of a reduced number of parts and to be simple in structure, making the transmission apparatus small in size, and ensures quicker and smoother gear changes with an electric motor.