Hybrid Drivetrain Creep Control via Slip-Managed Starting Element
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Solution Overview
Problem
Existing methods for operating parallel hybrid drive trains in motor vehicles face challenges in achieving fuel-saving, comfortable, and low-loss crawling, particularly in managing the interaction between the internal combustion engine and electric machine during creeping modes.
Innovation Solution
The method involves disengaging the clutch between the internal combustion engine and electric machine, actuating the brake pedal, and releasing it to bring the transmission-external or -internal starting element to filling pressure, allowing the electric machine to operate in speed-controlled mode with a defined slip speed, then closing the starting element to build a creeping torque while maintaining speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clutch is engaged to transmit torque during crawling, then the vehicle can move forward, but power loss and noise increase
Solution Approach 1:
The patent replaces the mechanical clutch engagement with an electromagnetic starting element (electrically actuated clutch) that can engage and disengage without continuous mechanical contact. This allows torque transmission during crawling while minimizing mechanical friction losses and noise, as the electromagnetic actuator can maintain engagement without the sliding friction inherent in traditional mechanical clutches.
Solution Approach 2:
The patent changes the operational parameters of the starting element by controlling its engagement state dynamically. During crawling, the starting element is kept in a partially engaged state with optimized friction characteristics, allowing sufficient torque transmission at low speeds while minimizing power loss. The system adjusts the engagement pressure and slip characteristics to optimize the balance between torque transmission and energy efficiency.
2Force
If the starting element is fully engaged to transmit torque, then crawling torque is sufficient, but vibrations and discomfort increase
Solution Approach 1:
The patent applies partial engagement of the starting element during crawling operations. Instead of full engagement, the system uses a controlled partial engagement that provides sufficient torque for crawling while avoiding the excessive friction and vibrations associated with complete engagement. This partial action principle allows the system to achieve the minimum necessary torque without the harmful effects of full mechanical contact.
Solution Approach 2:
The patent introduces a hydraulic or electromagnetic intermediary mechanism between the engine and transmission that mediates the torque transmission during crawling. This intermediary allows smooth torque transfer without direct mechanical contact, reducing vibrations and improving comfort while maintaining sufficient crawling torque. The intermediary actuator can modulate the engagement characteristics to optimize both torque transmission and vibration reduction.
3Speed
If the electric machine accelerates during crawling, then speed control is achieved, but electrical energy consumption increases
Solution Approach 1:
The patent employs periodic or pulsed acceleration of the electric machine during crawling rather than continuous high-speed operation. The electric machine accelerates in controlled intervals to maintain minimum crawling speed, then operates at lower speeds when full power is not needed. This periodic action reduces overall electrical energy consumption while still achieving the necessary speed control for comfortable crawling operation.
Solution Approach 2:
The patent enables the hybrid drive system to self-regulate its energy consumption during crawling by automatically optimizing the division of labor between the internal combustion engine and electric machine. The control system monitors vehicle speed, torque requirements, and energy state to determine the most energy-efficient operating mode, allowing the system to service itself by minimizing electrical energy consumption while maintaining required 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 enables fuel-efficient, comfortable, and low-loss crawling by minimizing power loss and noise, with the electric machine only accelerating when the brake pedal is released, thus conserving electrical energy and reducing vibrations.
Implementation Method 1
the starting element, which is operated in a torque setting mode, a creeping torque for creeping up at the output is built
Implementation Method 2
the electric machine of the hybrid drive, which is operated in a speed-controlled mode, is brought up to a speed
Implementation Method 3
the clutch connected between the internal combustion engine and the electric machine of the hybrid drive
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for operating a drivetrain comprising at least one hybrid drive system having an internal combustion engine (2) and an electric motor (3), a clutch (4) connected between the internal combustion engine and the electric motor, a transmission (5), a starting element (7, 9), and a brake pedal (11), wherein the procedure for electrically creeping from an initial state in which the clutch (4) is opened and the brake pedal (11) is actuated and the internal combustion engine is preferably switched off consists of first bringing the starting element (7, 9) to filling pressure or holding said element at filling pressure upon releasing or after releasing the brake pedal, bringing the speed-controlled electric motor (3) to a rotational speed immediately thereafter, so that the rotational speed thereof is greater than a transmission speed by a defined slip speed , and building up a creep torque by further closing the starting element (7, 9) at the output upon reaching said slip, wherein the electric motor (3) is thereby further speed controlled in order to maintain the slip.