Hybrid Vehicle Engine Speed Control for Acceleration
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Solution Overview
Problem
Existing hybrid vehicle systems lack sufficient acceleration responsiveness when the required driving force increases during deceleration traveling, as the target engine speed is not adjusted based on vehicle speed, leading to inadequate acceleration performance.
Innovation Solution
A hybrid vehicle system that includes a control mechanism to adjust the internal combustion engine's revolution based on traveling speed, using both rotating electric machines to manage driving force, with the control portion holding the engine's revolution at a predetermined value higher with increasing speed when the required driving force is 0 or less, and allowing the second rotating electric machine to generate power to support the first electric machine during acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target engine speed is set regardless of vehicle speed changes, then the control system is simple, but acceleration responsiveness is insufficient when the accelerator pedal is depressed
Solution Approach 1:
The patent applies dynamics by making the target engine speed variable based on vehicle speed. The control unit adjusts the target engine speed dynamically according to the detected vehicle speed, ensuring that the engine can respond appropriately to acceleration requests at different speed ranges. This resolves the contradiction by introducing adaptability without requiring complete system redesign.
Solution Approach 2:
The patent changes the parameter of target engine speed from a fixed value to a variable value that depends on vehicle speed. By establishing a relationship where target engine speed is adjusted based on detected vehicle speed, the system achieves better acceleration responsiveness across different operating conditions while maintaining a relatively simple control structure.
2Speed
If the internal combustion engine revolution is held at a higher predetermined value during deceleration, then acceleration responsiveness improves, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the target engine speed based on detected vehicle speed, holding it at a higher predetermined value during deceleration phases when acceleration responsiveness is needed, and allowing it to decrease when vehicle speed is low. This dynamic adjustment optimizes the balance between responsiveness and energy consumption.
Solution Approach 2:
The control unit performs preliminary action by holding the engine at a higher revolution during deceleration before acceleration is actually requested. This prepares the engine in advance so that when the accelerator pedal is depressed, the engine can respond immediately with sufficient power, avoiding the energy waste of having to rapidly increase revolutions from a lower state.
3Reliability
If the second electric machine motors the internal combustion engine to prevent stopping, then engine stability is maintained, but acceleration performance is reduced
Solution Approach 1:
The system dynamically determines the target engine speed based on vehicle speed and operational conditions. During deceleration, it holds the engine at a higher predetermined speed to maintain stability and prevent stopping, while during acceleration phases, it adjusts the target speed to enable sufficient acceleration performance, thus balancing reliability and speed requirements.
Solution Approach 2:
The control unit changes the target engine speed parameter according to the operational phase - maintaining a higher value during deceleration for stability and preventing engine stop, then adjusting to appropriate values during acceleration to ensure performance. This parameter adaptation resolves the contradiction between stability and acceleration performance.
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 acceleration responsiveness by ensuring the internal combustion engine can quickly reach the necessary revolution for increased output, regardless of traveling speed, improving acceleration performance without discomfort to the driver and protecting energy storage devices.
Implementation Method 1
a first rotating electric machine connected to an output shaft
Implementation Method 2
a second rotating electric machine connected to the internal combustion engine
Data Source
AI summary
A hybrid vehicle includes: a first rotating electric machine connected to an output shaft; an internal combustion engine; a second rotating electric machine connected to the internal combustion engine; a deriving portion configured to derive a required driving force based on an opening degree of an accelerator pedal operated by a driver of the hybrid vehicle; and a control portion configured to control the internal combustion engine, the first rotating electric machine, and the second rotating electric machine according to the required driving force. The control portion is configured to hold a revolution of the internal combustion engine at a predetermined value variable based on a travelling speed of the hybrid vehicle when the required driving force is 0 or less during travelling of the hybrid vehicle by power of the first rotating electric machine. The predetermined value is greater as the travelling speed is higher.