Vehicle Power Transmission Control Device Regenerative Torque Reduction
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Solution Overview
Problem
The existing control devices for vehicle power transmission systems struggle to provide proper oil pressure learning control during clutch-to-clutch shifts associated with regeneration, especially during coast down shifts, due to difficulties in distinguishing between undershoots caused by oil pressure timing and regenerative torque changes, leading to increased shift shock and reduced drivability.
Innovation Solution
A control device that executes regenerative torque reduction control before the torque phase begins during coast down shifts, stabilizing the regenerative torque and allowing for effective oil pressure learning control, thereby reducing shift shock and improving drivability by attributing torque changes solely to hydraulic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If regenerative torque reduction control is performed during the torque phase to compensate transmission output torque drop-off, then transmission output torque stability is improved, but it becomes difficult to distinguish between torque changes caused by oil pressure timing and those caused by regenerative torque changes, deteriorating oil pressure learning control precision
Solution Approach 1:
The regenerative torque reduction control is executed before the torque phase begins (during the inertia phase), rather than during the torque phase. This preliminary timing allows the regenerative torque to be stabilized before the engagement-side engagement device starts transmitting torque, thereby maintaining transmission output torque stability while enabling accurate detection of oil pressure timing effects during the torque phase without interference from regenerative torque changes.
2Power
If equal power shift is performed by varying regenerative torque according to electric motor rotation change, then regenerative power is maintained constant, but a drop-off in transmission output torque occurs during the torque phase and inertia phase, increasing shift shock
Solution Approach 1:
The regenerative torque reduction is performed in advance during the inertia phase before the torque phase begins. This preliminary action prevents the transmission output torque drop-off that would occur if equal power shift were maintained during the torque phase, thereby reducing shift shock while still allowing regenerative power to be approximately maintained during the inertia phase.
Solution Approach 2:
The regenerative torque is reduced in advance to counteract the anticipated torque drop-off that would occur during the torque phase. By performing this anti-action beforehand, the system prevents the harmful effect (shift shock) before it can occur during the critical torque phase when the engagement-side engagement device becomes active.
3Object-affected harmful factors
If oil pressure learning control is performed during clutch-to-clutch shift with regenerative torque changes, then shift shock suppression is improved, but the learning control accuracy deteriorates due to inability to distinguish undershoot causes
Solution Approach 1:
The regenerative torque reduction is completed before the torque phase begins, creating a clear separation between the inertia phase (where regenerative torque changes) and the torque phase (where oil pressure learning occurs). This timing arrangement allows oil pressure learning control to accurately detect undershoot causes during the torque phase without interference from regenerative torque changes, thereby maintaining both shift shock suppression and learning control accuracy.
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 regenerative torque reduction control ensures stable and constant torque output during the torque phase, reducing shift shock and enhancing drivability by isolating torque changes to hydraulic control, thus improving the responsiveness and smoothness of clutch-to-clutch shifts.
Implementation Method 1
performing regeneration through an electric motor coupled to an input shaft of the automatic transmission in a power transmittable manner
Implementation Method 2
an automatic transmission shifted by engagement and release of hydraulic friction engagement devices
Data Source
AI summary
It is provided a control device of a vehicle power transmission device having an automatic transmission shifted by engagement and release of hydraulic friction engagement devices to selectively establish a plurality of gear stages and an electric motor coupled to an input shaft of the automatic transmission in a power transmittable manner, the control device executing a clutch-to-clutch shift while performing regeneration through the electric motor at the time of a coast down shift of the automatic transmission, the control device completing regenerative torque reduction control to reduce a regenerative torque of the electric motor in a torque phase of the coast down shift before start of the torque phase in accordance with a drop-off of an output torque of the vehicle power transmission device.