Hybrid Powertrain Control for Seamless Gear Shifts
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Solution Overview
Problem
Existing hybrid powertrain systems face challenges in achieving seamless gear shifts without torque interruption and optimizing fuel consumption and exhaust treatment in combustion engines, often requiring complex and heavy clutch mechanisms that increase weight, cost, and reduce reliability.
Innovation Solution
A method for controlling a hybrid powertrain using a gearbox with two planetary gears and two electrical machines, where the moveable parts are disconnected to achieve a predetermined engine speed, allowing the electrical machines to control torque balance and desired torque in the output shaft, thereby optimizing fuel consumption and reducing the need for conventional clutches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clutch mechanisms are used to achieve seamless gear shifts, then torque interruption is avoided, but device complexity, weight, and cost increase while reliability decreases
Solution Approach 1:
The patent removes the conventional clutch mechanism from the powertrain system entirely. Instead of using a clutch to manage torque during gear shifts, the invention uses a planetary gear set with fixed and movable elements that can be selectively engaged or disengaged through braking forces applied to specific planetary gear components, thereby eliminating the need for complex clutch mechanisms while maintaining seamless gear shift capability
Solution Approach 2:
The patent replaces the mechanical clutch system with a hybrid system combining planetary gear mechanics and electrical machine control. The planetary gear set's movable elements are controlled through braking forces applied to planetary gears, substituting the traditional friction-based clutch mechanism with a more reliable mechanical-braking hybrid approach that reduces complexity and improves reliability
2Power
If the combustion engine is operated at high speeds to deliver maximum torque, then power output is improved, but fuel consumption increases and exhaust aftertreatment system is excessively cooled
Solution Approach 1:
The patent dynamically adjusts the combustion engine's operating speed based on real-time power demands. The control system monitors required torque and power output, adjusting the engine speed to operate within an optimized range rather than maintaining constant high speed. This dynamic control allows the engine to deliver required power while minimizing fuel consumption and preventing excessive cooling of the exhaust aftertreatment system
Solution Approach 2:
The patent changes the operating parameters of the combustion engine by controlling it to operate within a specific speed range determined by power and torque requirements. Instead of fixed high-speed operation, the engine speed is variable and adjusted according to actual demand, thereby optimizing the balance between power output and fuel efficiency while maintaining exhaust aftertreatment system temperature
3Use of energy by moving object
If electrical machines are used to control torque balance in planetary gears, then fuel consumption is optimized, but device complexity increases
Solution Approach 1:
The patent makes the electrical machines multi-functional by having them serve both as propulsion motors and as control devices for the planetary gear system. The same electrical machines that drive the vehicle also apply braking forces to the planetary gears to control torque balance during gear shifts, eliminating the need for separate control mechanisms and reducing overall system complexity while optimizing fuel consumption
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 efficient and reliable fuel optimization, reduces friction losses, and prevents excessive cooling of the exhaust aftertreatment system, resulting in a compact, lightweight, and cost-effective powertrain with improved reliability and reduced fuel consumption.
Implementation Method 1
The planetary gearbox usually comprises three components, which are rotatably arranged in relation to each other, namely a sun wheel, a planetary wheel carrier and an internal ring gear
Implementation Method 2
When the vehicle is braked, the electrical machine generates electric power, which is stored in the energy storage device. This is usually referred to as regenerative braking
Implementation Method 3
The electrical machine may thus alternately operate as a motor and as a generator, depending on the vehicle's operating mode
Data Source
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AI summary
The present invention relates to a method to start a hybrid powertrain (3) to optimise fuel consumption, wherein such hybrid powertrain (3) comprises a combustion engine (4); 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 combustion engine (4) is connected with a first planetary wheel carrier (50), arranged in the first planetary gear (10) via the input shaft (8) of the gearbox (2), 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: a) ensuring that the moveable parts (22, 26, 50) of the first planetary gear (10) are disconnected from each other, and that the moveable parts (28, 32, 51) of the second planetary gear (12) are disconnected from each other; b) bringing the combustion engine (4) to a predetermined engine speed (nice); and c) controlling the first and the second electrical machine (14; 16) in such a way that a desired torque (TDrv) is achieved in the output shaft (20). The invention also relates to a computer program (P) to control a hybrid powertrain (3) 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.