Automatic Downshift Control for Motorcycle Manual Transmissions
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Solution Overview
Problem
Conventional vehicles with manual transmissions struggle to perform smooth deceleration shifts without operating the main clutch, especially when the transmission gear ratio difference varies among gear positions, leading to difficulties in quickly adjusting engine power.
Innovation Solution
A vehicle with an automatic downshift function that includes an engine, throttle device, ignition device, engine speed sensor, shift operation member, manual transmission, and a controller that adjusts intake-air amount and ignition timing based on detected signals to control engine power during deceleration shifts, allowing for high responsiveness and fine adjustments regardless of gear position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If intake-air amount control is used to increase engine power during deceleration shift, then the target power can be reached, but the power responsivity is low and fine adjustment is difficult
Solution Approach 1:
The patent segments the engine power control into two independent components: intake-air amount control for achieving target power and ignition timing control for fine adjustment and quick responsivity. This segmentation allows each control mechanism to optimize its function without interfering with the other, resolving the contradiction between reaching target power and achieving fast responsivity.
Solution Approach 2:
The patent merges intake-air amount control and ignition timing control into a coordinated dual-control system. The intake-air amount is adjusted to reach the target power level, while ignition timing is simultaneously adjusted to provide fine-tuned power adjustment and rapid responsivity. This combination allows the system to achieve both high power responsivity and accurate target power attainment.
2Ease of operation
If the main clutch is disengaged to perform speed change, then the transmission gear position can be changed, but the shift operation becomes complex and time-consuming
Solution Approach 1:
The patent extracts the clutch disengagement operation from the deceleration shift process. By eliminating the requirement to disengage the main clutch, the system removes a complex and time-consuming step from the shift operation. The dog clutch type transmission can perform gear changes directly without preliminary clutch disengagement, significantly simplifying the operation and reducing shift time.
Solution Approach 2:
The transmission system performs the gear change operation autonomously without requiring manual clutch lever operation. The control system automatically manages the power transmission and gear engagement, allowing the rider to simply operate the shift pedal while the system handles the complex coordination of power cutoff and gear engagement, making the shift operation easier and faster.
3Device complexity
If the dog clutch type transmission is used, then the structure is simple, but the deceleration shift cannot be performed smoothly without main clutch operation in certain gear positions
Solution Approach 1:
The patent introduces dynamic control of engine power during the deceleration shift process. By dynamically adjusting the intake-air amount and ignition timing in response to shift operations, the system adapts the power delivery to facilitate smooth gear engagement. This dynamic power control enables the simple dog clutch transmission to perform smooth deceleration shifts across all gear positions, enhancing adaptability without increasing structural complexity.
Solution Approach 2:
The patent changes the engine operating parameters (intake-air amount and ignition timing) to enable smooth deceleration shift operation. By modifying these parameters during the shift transient, the system compensates for the limitations of the dog clutch transmission in certain gear positions, allowing smooth shifts without requiring structural modifications to the transmission itself.
Data Source
AI summary
A vehicle with an automatic downshift function, comprises an engine including a throttle device and an ignition device; an engine speed sensor which detects an engine speed; a shift operation member which is operated by a rider; a manual transmission connected to the engine, a shift operation sensor which detects the operation of the shift operation member; and a controller which controls the engine based on a detection signal of the engine speed sensor and a detection signal of the shift operation sensor. In a case where the controller determines that a deceleration shift operation has been initiated based on the detection signal of the shift operation sensor, the controller performs an automatic downshift control so that the controller controls the throttle device to increase an intake-air amount and controls the ignition device to change an ignition timing, based on the engine speed detected by the engine speed sensor.