Automatic Transmission Control Device for HEV Mode Switching
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Solution Overview
Problem
During mode switching from HEV to EV in automatic transmissions, the load variation of the motor/generator is erroneously determined as the engagement start of the frictional engagement element, leading to incorrect determination of engagement start.
Innovation Solution
A control apparatus for automatic transmission that includes a frictional engagement element and determination inhibit means, which inhibits the engagement start determination when switching from HEV to EV mode, ensuring accurate load variation assessment by maintaining the engagement start determination only when the frictional engagement element is engaged and the load is increased by a predetermined quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the engagement start determination is performed based on motor load variation during revolution number control, then the engagement start of the frictional engagement element can be detected, but during mode switching from HEV to EV mode, the load variation of the motor is erroneously determined as the engagement start
Solution Approach 1:
The control device performs preliminary identification of mode switching events before they occur. When the control device detects that the vehicle is in HEV mode and the clutch is engaged, it proactively identifies that an upcoming mode switch to EV mode will cause false load variations. This preliminary identification allows the system to prepare for and prevent erroneous engagement start determinations before they happen.
Solution Approach 2:
The control device introduces an intermediary mechanism (the identification unit) that mediates between the motor load variation signal and the engagement start determination logic. This intermediary layer filters out load variations caused by mode switching while allowing genuine engagement-related load variations to pass through, thereby resolving the contradiction between detecting real engagement events and avoiding false positives during mode transitions.
2Speed
If the motor load is monitored continuously to detect engagement start, then real-time detection is achieved, but mode switching causes false load variations that lead to erroneous determination
Solution Approach 1:
The control device performs preliminary identification of mode switching events before they occur. When the control device detects that the vehicle is in HEV mode and the clutch is engaged, it proactively identifies that an upcoming mode switch to EV mode will cause false load variations. This preliminary identification allows the system to prepare for and prevent erroneous engagement start determinations before they happen.
Solution Approach 2:
The control device introduces an intermediary mechanism (the identification unit) that mediates between the motor load variation signal and the engagement start determination logic. This intermediary layer filters out load variations caused by mode switching while allowing genuine engagement-related load variations to pass through, thereby resolving the contradiction between detecting real engagement events and avoiding false positives during mode transitions.
Data Source
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AI summary
There is provided a control apparatus for an automatic transmission AT into which driving forces from driving sources including an engine Eng and a motor/generator MG are inputted. The control apparatus includes: a second brake B2 engaged in a D range; engagement start determining means (steps S2 → S3 → S4); and determination inhibit means (steps S2 → S5 → S6). The engagement start determining means determines that second brake B2 has started the engagement in a case where a load of the motor/generator MG is increased by a predetermined quantity during the revolution number control and when the D range is selected and second brake B2 in the release state is engaged. The determination inhibit means inhibits the engagement start determination in a case where a switching from an HEV mode to an EV mode occurs in order to prevent an erroneous determination that the variation of the load which occurs due to the switching from HEV mode to the EV mode to the engagement start of the frictional engagement element.