Hybrid Driveline Engine Start Using Dual E-Machine Torque Control
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Solution Overview
Problem
In hybrid powertrains, the conventional clutch mechanism is heavy, costly, and inefficient, limiting torque transfer and increasing fuel consumption, while also requiring a large space and contributing to wear and reliability issues, especially in heavy vehicles where regenerative braking and multiple gear steps are necessary.
Innovation Solution
A method that disconnects the combustion engine from the gearbox using a coupling device, allowing the electrical machines to control torque and rotational speed to efficiently start the combustion engine, reducing the need for a conventional clutch and enabling compact, reliable, and efficient torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional clutch mechanism is used to connect the combustion engine to the gearbox, then torque transfer can be controlled, but the system becomes heavy, costly, and occupies large space
Solution Approach 1:
The patent replaces the conventional mechanical clutch mechanism with an electrical machine (motor/generator) that is electrically connected to the combustion engine and gearbox. The electrical machine controls torque transfer through electrical signals and electromagnetic fields, eliminating the need for heavy mechanical clutch discs and actuation mechanisms, thereby reducing weight while maintaining torque control capability
Solution Approach 2:
The electrical machine serves multiple functions: it acts as a motor to assist the combustion engine during vehicle acceleration, as a generator during regenerative braking to recover energy, and as a clutch substitute to control torque transfer during gear shifts. This multi-functionality eliminates the need for separate clutch mechanism, reducing overall system weight and component count
2Force
If a conventional clutch mechanism is used, then torque transfer can be controlled, but fuel consumption increases and wear occurs
Solution Approach 1:
The electrical machine replaces the mechanical clutch, eliminating friction-based torque control. The electrical machine uses electromagnetic fields to control torque transfer, which is more efficient and generates less energy loss. During regenerative braking, the electrical machine recovers kinetic energy that would otherwise be lost, directly reducing fuel consumption requirements
Solution Approach 2:
The control system dynamically adjusts the electrical machine's operating parameters (torque, speed, power factor) to optimize efficiency across different operating conditions. This allows for smooth, slip-free torque transfer during gear shifts, eliminating the energy-wasting friction and heat generation associated with conventional clutch operation
3Force
If a conventional clutch mechanism is used, then torque transfer can be controlled, but the device complexity and cost increase
Solution Approach 1:
The complex mechanical clutch system with multiple friction discs, pressure plates, springs, and actuation mechanisms is replaced by a relatively simple electrical machine with electromagnetic windings and a control unit. This substitution dramatically reduces mechanical complexity while adding controllable electronic torque management
Solution Approach 2:
The electrical machine performs multiple functions (motor, generator, clutch substitute) that would otherwise require separate mechanical components. This consolidation reduces the overall number of parts, simplifies the drivetrain architecture, and lowers both manufacturing and maintenance costs
4Force
If a conventional clutch mechanism is used, then torque transfer can be controlled, but the space required increases
Solution Approach 1:
The bulky mechanical clutch assembly with thick friction discs, pressure plates, and actuation linkages is replaced by a compact electrical machine. The electrical machine's electromagnetic components occupy significantly less space while providing equivalent or superior torque control, allowing for more compact vehicle packaging
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 a compact, lightweight, and cost-effective drive system with improved reliability and fuel efficiency by using electrical machines to manage torque and rotational speed, enabling quick engine start-ups and reducing wear on components.
Implementation Method 1
an electrical machine (16), which is connected to the second planetary gear (12)
Implementation Method 2
a first planetary gear (10), which is connected to the input shaft (8), a second planetary gear (12), which is connected to the first planetary gear (10)
Data Source
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AI summary
The invention relates to a method to start a combustion engine (4) in a hybrid powertrain (3), comprising a gearbox (2) with an input shaft (8) and an output shaft (20); a first planetary gear (10), connected to the input shaft (8) and a first main shaft (34); a second planetary gear (12), connected to the first planetary gear (10) and a second main shaft (36); a first electrical machine (14), connected to the first planetary gear (10); a second electrical machine (16), connected to the second planetary gear (12); at least one gear pair (Gl, 60, 72), connected with the first main shaft (34), and therefore with the first planetary gear (10) and the output shaft (20); and at least one gear pair (G2, 66, 78), connected with the second main shaft (36), and therefore with the second planetary gear (12) and the output shaft (20), wherein the input shaft (8) is connected with a first planetary wheel carrier (50), arranged in the first planetary gear (10), and wherein the second main shaft (36) is connected with a planetary wheel carrier (51), arranged in the second planetary gear (12). The method comprises the steps of: a) connecting an output shaft (97) of the combustion engine (4) with the input shaft (8) of the gearbox (2), via a coupling device (106), arranged between the output shaft (97) and the input shaft (8); and b) controlling the first and the second electrical machine (14, 16) in such a way that the combustion engine (4) is started. The invention also relates to a computer program (P) to start a combustion engine (4) and a computer program product comprising program code for an electronic control device (48) or another computer (53) to implement the method according to the invention.