Hybrid Gear Shifting via Electric Machine Torque Control
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Solution Overview
Problem
Existing vehicle control methods for hybrid vehicles with combustion engines and electric machines are inefficient during gear shifting, particularly when dealing with torque deviations and energy management, often requiring exhaust gas braking and lacking robustness.
Innovation Solution
Incorporating a second electric machine into the power assembly configuration, allowing for controlled energy transfer and torque distribution between the combustion engine and electric machines, enabling energy-efficient gear shifting by disconnecting the combustion engine from the planetary gearing and utilizing braking energy to store electric energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional clutch mechanism is used for gear shifting in hybrid vehicles, then the structure is simpler, but the energy efficiency deteriorates and torque deviations cannot be handled robustly
Solution Approach 1:
The patent merges the combustion engine with two electric machines through a planetary gearing system, creating an integrated power assembly where mechanical and electrical systems work together. The planetary gearing connects the combustion engine output shaft, the first electric machine rotor, and the gearbox input shaft, allowing seamless power transfer and energy recovery during gear shifting operations.
Solution Approach 2:
The first electric machine serves multiple functions: it acts as a motor to assist propulsion, as a generator to recover braking energy, and as a decoupling mechanism during gear shifts. The second electric machine provides additional braking capability and energy recovery, replacing the need for exhaust gas brakes while maintaining engine control during transitions.
2Loss of energy
If exhaust gas braking is used to brake the combustion engine during gear shifting, then the rotation speed can be controlled, but energy is wasted and emissions increase
Solution Approach 1:
The patent converts the harmful exhaust gas braking process into a beneficial energy recovery process. Instead of wasting braking energy through exhaust gases, the system uses the first and second electric machines as generators to convert the combustion engine's kinetic energy into electrical energy, which is then stored in the energy storage means. This eliminates emissions while recovering energy that would otherwise be lost.
Solution Approach 2:
The patent replaces the mechanical exhaust gas braking system with an electrical braking system using the first and second electric machines. The electric machines function as generators during braking, providing electromagnetic resistance to control engine speed while converting mechanical energy into electrical energy for storage, thereby eliminating the need for exhaust gas intervention.
3Reliability
If the combustion engine remains connected to the planetary gearing during gear shifting, then the connection is maintained, but torque deviations affect shifting robustness and time increases
Solution Approach 1:
The first electric machine acts as an intermediary between the combustion engine and the planetary gearing during gear shifting. By engaging the first locking means, the system decouples the combustion engine from the planetary gearing, allowing the engine to be controlled independently by the second electric machine while the gear shift proceeds without torque interference. This mediator role enables smooth transitions and maintains shifting robustness.
4Ease of operation
If a single electric machine is used in the hybrid power assembly, then the device complexity is reduced, but the ability to manage energy and torque during gear shifting is insufficient
Solution Approach 1:
The patent segments the electric machine function into two separate machines: the first electric machine is connected to the planetary gearing and handles power transfer and initial decoupling, while the second electric machine is directly connected to the combustion engine and handles engine braking and speed control. This segmentation allows each machine to specialize in specific tasks, improving overall energy and torque control during gear shifting operations.
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 allows for energy and time-saving gear shifting, reduces the need for exhaust gas braking, and maintains steady operation conditions, resulting in improved responsiveness and reduced emissions.
Implementation Method 1
When braking the vehicle the electric machine generates electric energy which may be stored
Implementation Method 2
By using a planetary gearing to interconnect the output shaft of the combustion engine, the rotor of the electric machine and the input shaft of the gearbox
Data Source
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AI summary
A method for obtaining gear shifting of a vehicle having a planetary gearing in the drive train, a combustion engine (2) with an output shaft (35) connected to a rotor of a second electric machine (30) and to a first component (10) of the planetary gearing, a first elec- tric machine (9) with a rotor connected to a third component (11) of the planetary gearing and an input shaft (3a) of a gearbox (3) connected to a second component (12) of the planetary gearing. The gear shifting procedure is started with the components of the planetary gearing interlocked by a locking means (34), in which they are released during the gear shifting and interlocked again after the gear shifting has been carried out.