Hybrid Drive Train Engine Starting via Electric Machine
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Solution Overview
Problem
Hybrid drive trains for motor vehicles often require a separate starter to start the internal combustion engine when it cannot reach ignition speed, especially at low speeds or when stationary, which adds complexity and weight to the powertrain.
Innovation Solution
The method involves disengaging the gear and closing the friction clutch to accelerate the internal combustion engine to ignition speed using the electric machine, allowing the engine to be started without a separate starter, and then transitioning to either pure combustion or hybrid driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate starter is provided to start the internal combustion engine at low speeds or when stationary, then the engine can be reliably started, but the device complexity and weight increase
Solution Approach 1:
The patent combines the starting function with the existing electric machine that is already coupled to the power transmission path. The electric machine serves dual purposes: propelling the vehicle during electric driving and starting the internal combustion engine when needed, eliminating the need for a separate starter motor and reducing overall system complexity
Solution Approach 2:
The electric machine is designed to perform multiple functions: it acts as a propulsion motor during electric driving operation and simultaneously serves as a starter for the internal combustion engine. This multi-functionality reduces the number of components needed in the powertrain system
2Device complexity
If the electric machine accelerates the internal combustion engine to ignition speed during electric driving, then the engine can be started without a separate starter, but there is a loss of traction and interruption in power transmission
Solution Approach 1:
The patent applies preliminary action by first disengaging the gear from the transmission unit before accelerating the internal combustion engine. This sequence prevents the engine acceleration process from interfering with power transmission to the wheels, minimizing traction interruption. The gear is re-engaged only after the engine reaches ignition speed and is ready to take over power delivery
Solution Approach 2:
The system dynamically adjusts the engagement state of the friction clutch and gear configuration during the engine starting process. The friction clutch is closed to connect the electric machine to the internal combustion engine for acceleration, while the gear is disengaged from the transmission unit to prevent load interference. These dynamic adjustments optimize the starting process while minimizing impact on traction
3Power
If the gear is disengaged to accelerate the internal combustion engine, then the engine can reach ignition speed without load, but the time for gear re-engagement increases the starting duration
Solution Approach 1:
The friction clutch is closed in a preparatory step before the gear is disengaged from the transmission unit. This preliminary action establishes the power connection between the electric machine and internal combustion engine early in the sequence, allowing immediate acceleration once the gear is disengaged, and enables faster re-engagement without delay
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 eliminates the need for a separate starter, reduces the time and traction interruption during engine starting, and allows for lightweight powertrain design while enabling smooth transitions between electric and combustion engine operation.
Implementation Method 1
a friction clutch (16, 18) which can be closed or opened at will... closing the friction clutch... with the friction clutch being set in a preparatory step before the gear is disengaged in order to accelerate the internal combustion engine
Data Source
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AI summary
The method involves coupling gear assembly (14) with a power transmission path to an internal combustion engine (12). The power transmission path comprises a friction clutch (16) and a gear unit (20). The gear ratio and closing of the friction clutch is laid out and the internal combustion engine is accelerated to a firing speed and the engine is started. An independent claim is included for a method for controlling unit for operating a hybrid drive train.