Vehicle Transmission Backlash Control for Shock-Free State Switching
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Solution Overview
Problem
Vehicles with transmission members having backlash experience shocks during changes in the drive source state due to speed differences between dog elements, leading to inefficient acceleration and deceleration responses.
Innovation Solution
A control device is implemented to manage power reduction and increase processes by controlling the timing of these processes relative to the switching of transmission states, ensuring the power reduction starts prior to and ends after the state change, thereby minimizing torque transmission and reducing shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If backlash is provided between dog elements to allow smooth gear shifting, then gear engagement smoothness is improved, but shock occurs during transmission state switching due to speed differences
Solution Approach 1:
The control device performs preliminary action by reducing power output before the transmission state switching occurs. The control device determines that transmission state switching is occurring or has occurred, and then reduces power output from the drive source. This preliminary power reduction minimizes the speed difference between dog elements during engagement, thereby suppressing shock while maintaining backlash for smooth shifting.
2Object-affected harmful factors
If power output is reduced to suppress shock during transmission switching, then vehicle shock is minimized, but acceleration response becomes slower
Solution Approach 1:
The control device dynamically adjusts power output based on the transmission state. Power output is reduced only during the brief period when transmission state switching is detected, and then restored to normal levels afterward. This dynamic control suppresses shock during switching while maintaining fast acceleration response during steady-state operation.
3Reliability
If backlash size is increased to ensure smooth dog element engagement, then engagement reliability is improved, but torque transmission instability increases during state transitions
Solution Approach 1:
The control device uses feedback by detecting transmission state switching and using this information to control power output. The control device determines when transmission state switching occurs and adjusts power output accordingly, providing stable torque transmission during state transitions while maintaining the backlash necessary for reliable engagement.
Data Source
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Figure 3A~3C
AI summary
The present teaching provides a vehicle including first and second transmission members having backlash therebetween and being rotatable relative to each other, the vehicle being capable of suppressing a shock caused by change in state of a drive source, and having improved acceleration or deceleration response. The vehicle includes the drive source, a driven member, and a control device. The control device executes at least one of a power reduction process reducing transmission torque transmitted between the first and second transmission members at switching from non-transmission state to acceleration transmission state or a power reduction process reducing the transmission torque at switching from non-transmission state to acceleration transmission state. The control device sets a time to start at least one of these processes at a time equal to or prior to the switching time, and sets a time to end the at least one of these processes later than a switching time from non-transmission state to acceleration or deceleration transmission state.