Hybrid Powertrain Control for Smooth Start and Reduced Clutch Wear
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Solution Overview
Problem
Hybrid powertrains face challenges in reducing fuel consumption, clutch wear, and improving ride comfort due to the combustion engine's limited torque at low speeds, requiring multiple gear shifts and torque interruptions during start-up.
Innovation Solution
A method controlling a hybrid powertrain by disconnecting the combustion engine, engaging a higher starting gear, using the electric machine to generate torque, and connecting the combustion engine when rotational speeds match, allowing for a smoother start and reduced gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the vehicle is started with the combustion engine in low gear to overcome limited torque at low speeds, then the vehicle can be brought into motion, but multiple gear shifts are required which increases fuel consumption and causes torque interruptions
Solution Approach 1:
The patent combines the combustion engine and electric machine into a hybrid powertrain system where both power sources can work together. The electric machine provides immediate torque assistance during start-up, allowing the combustion engine to operate more efficiently while reducing the need for multiple gear shifts, thereby lowering overall fuel consumption.
Solution Approach 2:
The electric machine is activated before the combustion engine reaches optimal operating speed to provide preliminary torque assistance during start-up. This preliminary action from the electric machine enables smoother acceleration and reduces the number of gear shifts required, improving fuel efficiency from the outset.
2Speed
If multiple gear shifts are performed during start-up to achieve target speed, then the vehicle can reach desired speed, but ride comfort deteriorates due to torque interruptions
Solution Approach 1:
The electric machine provides continuous torque during start-up and acceleration, bridging the gaps that would otherwise occur during gear shifts. This continuous torque delivery from the electric machine ensures smooth operation and maintains ride comfort while the vehicle reaches target speed.
Solution Approach 2:
The electric machine acts as an intermediary between the combustion engine and the drivetrain during transient operations. It compensates for torque interruptions during gear shifts, providing smooth power delivery that enhances ride comfort while enabling the vehicle to reach desired speeds.
3Force
If the combustion engine operates at higher speeds during start-up to deliver sufficient torque, then torque availability improves, but fuel consumption increases
Solution Approach 1:
The electric machine provides partial torque during start-up, allowing the combustion engine to operate at lower, more efficient speeds than would be required if it had to provide all the torque alone. This partial assistance from the electric machine enables the combustion engine to stay in its optimal efficiency range while still delivering sufficient total torque.
Solution Approach 2:
The system dynamically changes the operating parameters of the combustion engine by using the electric machine to supplement torque during transient conditions. This allows the combustion engine to operate at lower speeds with better fuel efficiency while the electric machine makes up the difference in torque requirements.
4Stability of the object's composition
If the vehicle is brought into motion with frequent gear shifts, then the combustion engine can operate in its optimal speed range, but clutch wear increases
Solution Approach 1:
The electric machine performs preliminary acceleration during start-up, reducing the number of gear shifts the clutch must handle. By providing torque assistance before the combustion engine is fully engaged, the electric machine lessens the clutch's workload and extends its service life.
Solution Approach 2:
The patent converts the electric machine's capability into a benefit that protects the clutch from excessive wear. The electric machine absorbs the stress of frequent gear shifts and start-up torque requirements, thereby preserving the clutch and extending its durability.
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 reduces fuel consumption, minimizes clutch wear, and enhances ride comfort by enabling a full electric start with higher gears, reducing the number of gear shifts and maintaining torque availability during the start process.
Implementation Method 1
generating a torque in the input shaft with the electric machine, accelerating the electric machine
Data Source
AI summary
The present invention relates to a method to control a hybrid powertrain, comprising a combustion engine, an electric machine, a gearbox with input shaft and output shaft, wherein the combustion engine and the electric machine are connected to the input shaft. The method comprises the following steps: a) disconnecting the combustion engine from the input shaft with a coupling device, b) engaging a starting gear in the gearbox, which starting gear is higher than the gear at which the combustion engine's torque at idling speed is able to operate the input shaft, c) generating a torque in the input shaft with the electric machine, d) accelerating the electric machine, and e) connecting the combustion engine to the input shaft with the coupling device when the electric machine has reached substantially the same rotational speed as the combustion engine. The invention also relates to a hybrid powertrain and a vehicle.