Vehicle Shift Control Device Torque Capacity Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In vehicles with internal combustion engines and multi-speed transmissions, downshift control can cause shocks due to internal inertia during torque-up control in a neutral state, leading to drivability issues.
Innovation Solution
A shift control device that adjusts the torque capacity and hydraulic pressure of engagement devices before torque-up control, setting the engagement-side engagement device's torque capacity to a value greater than zero and increasing the instruction pressure for large internal inertia shift patterns, and adjusting release-side engagement device pressures to prevent rotation speed drops and drive force loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If torque-up control is performed in a neutral state during downshift, then input shaft rotation speed can be synchronized with post-shift rotation speed, but shock occurs due to internal inertia transmitting drive force to the output side
Solution Approach 1:
The engagement-side engagement device is preliminarily engaged before torque-up control starts, establishing initial torque capacity to prevent internal inertia from transmitting drive force to the output side during subsequent torque-up operation
Solution Approach 2:
The engagement-side engagement device applies preliminary counter-torque to offset the harmful effect of internal inertia before torque-up control begins, preventing the shock that would otherwise occur during rotation speed synchronization
2Device complexity
If engagement-side engagement device torque capacity is set to zero before torque-up control, then control simplicity is maintained, but rotation speed synchronization performance deteriorates
Solution Approach 1:
The torque capacity parameter of the engagement-side engagement device is changed from zero to a predetermined value before torque-up control starts, optimizing the balance between control simplicity and rotation speed synchronization performance
Data Source
AI summary
A shift control device of a vehicle including an internal combustion engine and a multi-speed transmission in series, the shift control device comprises: a control portion providing a downshift control in which an input shaft rotation speed of the multi-speed transmission is increased through a torque-up of the internal combustion engine toward a post-shift input shaft rotation speed in a neutral state where a release-side engagement device to be released during a downshift of the multi-speed transmission is released, so as to engage an engagement-side engagement device to be engaged after the shift. In the case of a shift pattern having a large internal inertia of the multi-speed transmission, the control portion controls a torque capacity of the engagement-side engagement device to a value greater than zero before starting a torque-up control of the internal combustion engine.