Hybrid Powertrain Torque Balancing for Standstill Acceleration
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Solution Overview
Problem
Hybrid powertrains face limitations in efficiently moving off from a standstill and extending the life of energy storage devices due to torque limitations from electrical machines and the need for compact, reliable drive arrangements, especially in heavy vehicles, where conventional clutches and energy storage devices contribute to increased costs, weight, and reduced reliability.
Innovation Solution
The method involves disconnecting planetary gear components during vehicle startup, using torque balancing to eliminate power transfer through energy storage devices, and employing coupling devices and locking mechanisms to enable synchronous rotational speeds between sun wheels and planetary wheel carriers, allowing the electrical machines to generate torques independently without energy storage device involvement, thus reducing wear and increasing device lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electrical machine is used to provide torque during vehicle acceleration, then the vehicle can achieve faster acceleration response, but the maximum torque is limited by the electrical machine's strength and gearing
Solution Approach 1:
The patent combines the combustion engine and electrical machine into a hybrid powertrain system where both power sources can operate simultaneously. The planetary gear set merges their torque outputs, allowing the system to achieve both the fast response of the electrical machine and the high torque of the combustion engine without being limited by either component alone.
Solution Approach 2:
The electrical machine is designed to serve multiple functions: it can operate as a motor during acceleration, as a generator during regenerative braking, and its torque contribution can be modulated to balance the total system torque. This multi-functionality allows the system to optimize acceleration response while managing the electrical machine's torque limitations.
2Ease of operation
If a conventional clutch mechanism is used to disconnect the combustion engine during shifting, then gear changes can be achieved, but the clutch mechanism increases weight, cost, and occupies space
Solution Approach 1:
The patent extracts the clutch mechanism from the hybrid powertrain by using the planetary gear set and control system to manage torque distribution between the combustion engine and electrical machine. This eliminates the need for a conventional clutch while maintaining gear shifting capability through electronic control of the electrical machine's torque contribution.
Solution Approach 2:
The mechanical clutch system is replaced with an electronically controlled torque management system. The electrical machine's torque can be rapidly adjusted via electronic control to achieve the same disconnection effect as a clutch, eliminating mechanical wear and reducing the weight and complexity of the shifting mechanism.
3Force
If the electrical machine operates at high torque during acceleration, then the vehicle achieves better performance, but the energy storage device must handle increased power cycling which reduces its life
Solution Approach 1:
The patent applies partial action by having the electrical machine provide only the necessary portion of torque during acceleration, rather than operating at maximum capacity. The combustion engine supplements the torque output, allowing the electrical machine to operate at moderate torque levels that extend energy storage device life while still achieving the desired acceleration performance through combined power output.
4Device complexity
If the planetary gear components are kept connected during startup, then the structure remains simple, but the electrical machine cannot generate sufficient torque due to torque limitations
Solution Approach 1:
The patent introduces dynamic control of the planetary gear connections during startup. The connections are temporarily modified or controlled to allow the electrical machine to operate independently and generate sufficient torque without being constrained by the torque limitations that would exist if all planetary gear components remained permanently connected in the standard configuration.
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 vehicle acceleration from standstill without energy storage device usage, prolongs the life of energy storage devices by reducing power cycling, and achieves a compact, lightweight, and cost-effective drive arrangement with enhanced reliability and dependability.
Implementation Method 1
activating the first electrical machine (14) and the second electrical machine (16), so that the first electrical machine (14) rotates in the opposite direction to the second electrical machine (16), whereat a torque is generated in the output shaft (20)
Data Source
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AI summary
Method for moving off of a vehicle with a hybrid powertrain (3), comprising a combustion engine (4); a gearbox (2) with an input shaft (8) and an output shaft (20); a first planetary gear (10), which is connected to the input shaft (8) and a first main shaft (34); a second planetary gear (12), which is connected to the first planetary gear (10) and a second main shaft (36); a first electrical machine (14), which is connected to the first planetary gear (10); a second electrical machine (16), which is connected to the second planetary gear (12), wherein the electrical machines (14, 16) may operate each other; at least one gear pair (G1, 60, 72), connected with the first planetary gear (10) and the output shaft (20); and at least one gear pair (G2, 66, 78), connected with the second planetary gear (12) and the output shaft (20), wherein the combustion engine, via the input shaft (8), is connected with a first planetary wheel carrier (50), arranged in the first planetary gear (10), wherein the second main shaft (36) is connected with a second planetary wheel carrier (51), arranged in the second planetary gear (12). The method comprises the steps of, while the combustion engine (4) is in operation: a) ensuring that the rotatable components (26, 50) of the first planetary gear (10) are disconnected from each other, and ensuring that the rotatable components (32, 51) of the second planetary gear (12) are disconnected from each other, b) ensuring that at least one gear is engaged, corresponding to the at least one gear pair (G1, 60, 72), which is connected with the first planetary gear (10), and/or the least one gear pair (G2, 66, 78), which is connected with the second planetary gear (12), and c) activating the first electrical machine (14) and the second electrical machine (16), so that the total power output from the first and second electrical machines (14, 16) is zero, and so that a torque is generated in the output shaft (20). The invention also relates to a vehicle (1), which is moved off according to the method according to the invention. The invention also relates to a computer program (P) to move off a vehicle with 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.