CVT Control Device for Straddle-Type Vehicle Engine Start
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Solution Overview
Problem
In straddle-type vehicles equipped with V-belt type continuously variable transmissions, the inconsistency between rider operation and vehicle acceleration when starting the engine after coasting down a slope can cause an unpleasant sensation due to sudden clutch engagement, as the speed change ratio mechanism adjusts based on pre-programmed vehicle speed and engine speed.
Innovation Solution
A control device is implemented that sets multiple driving modes, allowing it to switch to a predetermined driving mode before engine start, limits mode switching when the engine is not started, and ensures consistent mode engagement at engine start, thereby maintaining constant drivability and reducing unpleasant sensations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a mechanism that changes the speed change ratio in response to vehicle speed is used, then automatic speed adjustment is achieved, but sudden clutch engagement occurs when the engine is started after coasting down a slope, causing inconsistency between rider operation and vehicle acceleration
Solution Approach 1:
The control device determines in advance that when the vehicle is coasting down a slope (detected by engine braking state), the engine should be started in a specific driving mode (e.g., second driving mode with higher speed change ratio) to prevent sudden clutch engagement. This preliminary determination ensures smooth acceleration from the start state.
Solution Approach 2:
The control device continuously monitors vehicle state (engine braking detection, vehicle speed, clutch engagement state) and adjusts the driving mode selection based on this feedback. When engine start is detected during coasting, the control device selects an appropriate driving mode to maintain consistent drivability.
2Adaptability or versatility
If multiple driving modes are available for selection, then rider preference and different driving conditions can be accommodated, but mode switching may cause inconsistency when the engine is started after coasting
Solution Approach 1:
The control device determines in advance the appropriate driving mode for engine start based on current vehicle state. When coasting down a slope is detected, the control device pre-selects a specific driving mode (e.g., second driving mode) to be active at engine start, preventing mode switching inconsistencies.
Solution Approach 2:
Instead of allowing the rider-selected driving mode to remain active at engine start, the control device inverts the logic by automatically selecting a predetermined driving mode when specific conditions (coasting down slope) are detected, overriding the normal mode selection process.
Data Source
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Figure 3(a)~3(c)
AI summary
A straddle-type vehicle (100) includes a control device (10) that controls a continuously variable transmission (30). A plurality of driving modes ("A" and "B") are set in the control device (10) . The control device (10) performs: a first control that switches the driving mode to a determined driving mode ("A") among the plurality of driving modes before start of the engine; a second control that switches between the plurality of driving modes ("A") and ("B)" in response to operation of a mode switching operation member; and a third control that limits the second control and inhibits switching from the determined driving mode ("A") to the other driving mode ("B"), when the control device detects that the engine has not been started.