Hybrid Powertrain Engine Speed Control for Acoustic Feedback
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Solution Overview
Problem
Serial-parallel hybrid powertrains in motor vehicles experience reduced customer acceptance due to unfamiliar and negative acoustic feedback during acceleration from low speeds, characterized by the 'rubber band effect', where the internal combustion engine noise dominates and is perceived as unnatural.
Innovation Solution
A method for operating a serial-parallel hybrid powertrain that involves mechanically decoupling the internal combustion engine from the wheels, allowing the second electric machine to accelerate the vehicle while increasing the internal combustion engine's speed in a predefined ratio, simulating a conventional driving experience by correlating engine noise and vibrations with acceleration, and using the hybrid energy store to compensate for power deficits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the internal combustion engine operates at high speed to generate sufficient electrical energy during acceleration from low speed, then the power demand is met, but driving noise dominates and creates an unfamiliar acoustic state perceived negatively by drivers
Solution Approach 1:
The patent changes the rotational speed parameter of the internal combustion engine during acceleration. Instead of operating at constant high speed to maximize power generation, the engine speed is dynamically adjusted to follow a predefined characteristic curve that correlates with vehicle acceleration, reducing noise while maintaining sufficient power output through coordinated control of the first and second electric machines
2Speed
If the internal combustion engine is mechanically decoupled from the wheels in serial mode, then acceleration from low speeds is achieved using only the second electric machine, but the acoustic feedback becomes unfamiliar and negative due to the dominant engine noise
Solution Approach 1:
The patent implements a feedback mechanism where the rotational speed of the internal combustion engine is continuously adjusted based on the vehicle's acceleration state. The control system monitors acceleration and modifies engine speed accordingly, creating a closed-loop system that optimizes both performance and acoustic characteristics
Solution Approach 2:
The patent introduces dynamic control of the internal combustion engine's rotational speed during acceleration operations. The engine operates according to a predefined speed characteristic that changes with acceleration demand, transforming the static high-speed operation into a dynamic, adaptive process that improves acoustic feedback
3Ease of manufacture
If a naturally aspirated engine is used designed to deliver maximum power at one rotational speed point close to maximum speed, then the engine design is simplified, but the acoustic state during acceleration becomes unfamiliar and negative
Solution Approach 1:
The patent replaces the traditional mechanical coupling between engine speed and vehicle acceleration with an electrical control system. The first electric machine acts as a decoupling element, allowing the internal combustion engine to operate independently according to optimized speed characteristics rather than being directly tied to wheel speed through mechanical transmission
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 method enhances customer acceptance by providing a more familiar and realistic driving experience, reducing the perception of direct rotational speed and acceleration relationship, and improving overall vehicle efficiency.
Implementation Method 1
The internal combustion engine drives the first electric machine, so that the latter generates electrical current and feeds it into the battery or provides it directly to the second electric machine
Implementation Method 2
The drive torque is then provided solely by the second electric machine
Implementation Method 3
a battery that is designed for receiving electrical energy from the first electric machine and the second electric machine, and for delivering electrical energy to the first electric machine and the second electric machine
Data Source
AI summary
A method for operating a serial-parallel hybrid powertrain of a motor vehicle has the steps of mechanically decoupling the internal combustion engine from the wheels of the motor vehicle, accelerating the motor vehicle from a first speed to a second speed by means of the second electric machine, and increasing the speed n of the internal combustion engine from a first rotational speed to a second rotational speed. Increasing the speed of the internal combustion engine from the first rotational speed to the second rotational speed always takes place as a function of the increase in the speed of the motor vehicle from the first speed to the second speed. A motor vehicle may have such a serial-parallel hybrid powertrain.