Hybrid Vehicle Engine Control During Series Mode Gear Shifts
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Solution Overview
Problem
In series hybrid vehicles, engine efficiency is reduced during gear shifts due to temporary changes in engine power command, leading to prolonged gear shift durations and inefficient operation when the traction motor output is reduced to zero.
Innovation Solution
A method that maintains engine operating conditions by redirecting electric power from the traction motor to a battery during gear shifts, reducing engine load and optimizing power distribution to minimize engine power changes, thereby improving efficiency and reducing gear shift time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the traction motor output is reduced to zero during gear shift, then the gear shift can be initiated, but the engine efficiency is reduced and gear shift duration is prolonged
Solution Approach 1:
The patent introduces the battery as an intermediary energy storage device between the engine and traction motor. During gear shift, the battery acts as a mediator by absorbing or supplying electrical power, allowing the engine to maintain its operating conditions while the traction motor output is temporarily reduced. This intermediary component resolves the contradiction by decoupling the engine operation from the temporary power demand changes during gear shift.
Solution Approach 2:
The patent dynamically changes the power distribution parameters by redirecting electrical power flow between the engine, traction motor, and battery based on the gear shift state. When gear shift is detected, the system changes the electrical load parameters on the engine by adjusting the charging/discharging rate of the battery, thereby maintaining engine operating conditions while enabling the traction motor to reduce output for smooth gear transition.
2Ease of operation
If the engine power command is temporarily changed to reduce input torque to transmission, then gear shift can be executed, but the gear shift duration is prolonged due to slower engine response
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the electrical power distribution to the battery before the actual gear shift occurs. The control system detects the gear shift intent and提前 redirects the electrical load from the traction motor to the battery, allowing the engine to maintain its power command without needing to respond to temporary power reductions. This preliminary power redistribution eliminates the delay associated with engine response time.
Solution Approach 2:
The battery serves as an intermediary that can rapidly absorb or supply electrical power without the mechanical inertia constraints of the engine. During gear shift, the battery mediates the power transition by quickly adjusting its charge/discharge state, enabling the traction motor output to be reduced to zero for gear engagement while the engine maintains steady operation, thereby shortening the overall gear shift duration.
3Ease of operation
If the traction motor power is reduced for gear shift, then transmission input torque is reduced, but engine operating conditions must be adjusted which reduces efficiency
Solution Approach 1:
The battery acts as an intermediary electrical energy buffer between the engine and traction motor. When the traction motor power is reduced for gear shift, the battery mediates by absorbing the displaced electrical power through charging, allowing the engine to maintain its original operating conditions without adjustment. This eliminates energy loss while still achieving the necessary torque control for smooth gear shifting.
Solution Approach 2:
The patent changes the electrical power distribution parameters by dynamically adjusting the battery charge/discharge rate based on the gear shift state. When gear shift is detected, the system increases the electrical load on the battery, thereby maintaining constant engine operating parameters while achieving the required reduction in transmission input torque through battery-mediated power redistribution.
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 enhances engine efficiency and reduces gear shift duration by minimizing engine power fluctuations, improving overall vehicle performance and customer satisfaction.
Implementation Method 1
the engine and the ISG may supply electric power to the traction motor while the vehicle is operating in a series mode of operation
Implementation Method 2
A first power source of a hybrid vehicle may be an engine powered via fuel, and a second power source may be an electric motor/generator powered via electrical energy
Data Source
AI summary
Methods and systems are provided for controlling engine operation in response to a request to shift a transmission gear. In one example, a method may include maintaining operating conditions of an engine and redirecting electric power generated via the engine from a traction motor to a battery in response to a request to shift a transmission while the driveline is operating in a series mode. In this way engine efficiency may be improved and a time frame for shifting a transmission gear may be reduced responsive to a gear shift request while the powertrain is operating in series mode.