Hybrid Vehicle Torque Control During Upshifts
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Solution Overview
Problem
Hybrid vehicles with engines and motors as drive power sources face challenges in efficiently managing torque during gear shifts, which can lead to gear shift shock and potentially degrade the performance and durability of exhaust gas control catalysts due to inconsistent temperature management.
Innovation Solution
A control device and method that dynamically adjust torque input to the transmission by determining the operable state of the engine during gear shifts, using a combination of engine torque reduction and motor-assisted torque control to manage the input shaft rotation speed, thereby preventing excessive catalyst overheating and maintaining catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ignition timing is retarded to decrease engine torque during upshift, then gear shift shock is suppressed, but exhaust gas control catalyst temperature becomes excessively high causing degraded catalyst activity and durability
Solution Approach 1:
The motor acts as an intermediary device to control input shaft torque during upshift. Instead of relying solely on ignition timing retardation, the motor provides precise torque control to suppress gear shift shock while allowing the exhaust gas control catalyst to maintain appropriate temperature for its function and durability.
2Ease of operation
If ignition timing is constantly retarded during upshift to suppress gear shift shock, then gear shift smoothness is improved, but exhaust gas control catalyst temperature becomes excessively high
Solution Approach 1:
The control system dynamically adjusts ignition timing based on the operational phase of upshift. During the initial phase, ignition timing is retarded to suppress gear shift shock. As the upshift progresses and the input shaft rotation speed approaches the target speed, ignition timing is returned to normal to prevent excessive catalyst temperature.
Solution Approach 2:
The ignition timing control is applied periodically and temporarily only during the specific phase when gear shift shock occurs, rather than being constantly applied. This periodic control suppresses shock while minimizing the duration of high-temperature exhaust gas exposure to the catalyst.
3Device complexity
If motor torque control is used evenly throughout upshift, then input shaft rotation speed control is simplified, but fuel efficiency and catalyst warming-up characteristics are not optimized
Solution Approach 1:
The control system dynamically adjusts motor torque output based on the upshift phase and catalyst temperature conditions. When catalyst warming is needed, the system prioritizes maintaining catalyst temperature over minimal motor intervention. When warming is sufficient, the system uses motor torque control to optimize fuel efficiency during upshift.
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
This approach effectively reduces gear shift shock and maintains catalyst performance by appropriately managing torque during upshifts, ensuring efficient fuel use and prolonged catalyst durability.
Implementation Method 1
a first motor configured to have an electric power generation function of increasing or decreasing torque input from the engine to the automatic transmission
Implementation Method 2
an exhaust gas control catalyst configured to remove combustion exhaust gas discharged from the engine
Data Source
AI summary
It is provided a control device for a hybrid vehicle including a controller configured to control an engine, a first motor, and an automatic transmission and a control method of the hybrid vehicle. The controller is configured to determine whether or not an operation state of the engine is changeable, when an upshift of the hybrid vehicle is performed, decrease torque of an input shaft of the automatic transmission by outputting negative torque acting to decrease the torque of the input shaft of the automatic transmission from the first motor when a prohibition condition that the operation state of the engine is not changeable is established, and decrease engine torque output from the engine to decrease the torque of the input shaft of the automatic transmission to be decreased accompanied by the upshift when the prohibition condition is not established and the operation state of the engine is changeable.