Hybrid Powertrain Engine Disconnect Clutch Torque Control
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Solution Overview
Problem
Hybrid drive powertrains face challenges in efficiently managing torque distribution between internal combustion engines and electric motors, particularly during engine start-up and shut-down scenarios, which affects fuel efficiency and drivability.
Innovation Solution
A powertrain configuration with a first electric motor connected to the engine via a ratio changing device and a second motor selectively coupled through an engine disconnect clutch, allowing for monitoring and control of propelling torque and speed to select appropriate control modes for the motors and clutch, enabling efficient torque management and engine start strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is shut down to save fuel, then fuel efficiency is improved, but the powertrain must supply torque to turn the shut down engine overcoming friction and pumping forces
Solution Approach 1:
The engine disconnect clutch extracts the engine from the powertrain system when shutdown occurs, physically separating the engine crankshaft from the transmission input shaft. This prevents the powertrain from needing to supply torque to overcome engine friction and pumping forces, resolving the contradiction between fuel savings and torque requirements.
Solution Approach 2:
The engine disconnect clutch acts as an intermediary device between the engine and powertrain. When the clutch is disengaged, it mediates the interaction by allowing the engine to remain stationary while the powertrain operates independently, eliminating the torque conflict without requiring the engine to be physically removed.
2Ease of operation
If a clutch device is used to disconnect the engine from the powertrain, then the engine can remain shut down while the powertrain functions, but device complexity increases
Solution Approach 1:
The engine disconnect clutch serves multiple functions: it disconnects the engine during shutdown to eliminate torque conflicts, connects the engine during startup to allow motor-assisted cranking, and manages power flow between the engine and powertrain. This multi-functionality reduces the need for additional specialized components, offsetting the complexity increase.
3Reliability
If torque is supplied to start the engine during cold cranking, then the engine can be started, but the motor operates in a less efficient region
Solution Approach 1:
The system performs preliminary actions by pre-charging the energy storage device (battery) during periods when the engine is running and the motor is not needed for starting. This stored energy is then available during cold cranking events, allowing the motor to operate more efficiently rather than drawing excessive power during the start event itself.
Solution Approach 2:
The system merges the starting function with the powertrain operation by using the same motor that provides propulsion also to perform engine cranking. The control system coordinates the motor's dual role, optimizing the transition between propulsion mode and starting mode to minimize efficiency losses.
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 configuration enhances fuel efficiency by optimizing torque distribution, enabling smooth engine start-ups and shut-downs, and maintains drivability by synchronizing motor operations to minimize torque disturbances and preserve vehicle performance.
Implementation Method 1
a first electric motor coupled to an internal combustion engine with a ratio changing device
Implementation Method 2
a second motor selectively coupled to the engine through an engine disconnect clutch, the second motor further coupled to an input shaft of a transmission
Implementation Method 3
a first electric motor coupled to an internal combustion engine with a ratio changing device
Data Source
AI summary
A powertrain includes a first electric motor coupled to an internal combustion engine with a ratio changing device and a second motor selectively coupled to the engine through an engine disconnect clutch, the second motor further coupled to an input shaft of a transmission. A method to control the powertrain includes monitoring a propelling torque provided by the second motor, monitoring a speed of the second motor, determining a condition of the second motor based upon the propelling torque and the speed of the second motor, selecting a control mode for the first motor based upon the condition of the second motor and controlling the first motor, the second motor, and the engine disconnect clutch based upon the control mode.