Hybrid Powertrain Gear Shift via Planetary Coupling
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Solution Overview
Problem
Conventional hybrid powertrains face challenges in achieving gear shifts without torque interruption and optimal brake regeneration, while also requiring a large torque and a large number of gear steps, which is not efficiently addressed by existing technologies.
Innovation Solution
The method involves a hybrid powertrain configuration with two planetary gears, electrical machines, and a range gearbox, utilizing coupling devices and synchronizing mechanisms to enable seamless gear shifts and torque transfer without interruption, allowing for a compact, efficient, and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional clutch mechanism is used to disconnect the gearbox input shaft from the internal combustion engine during shifting processes, then gear shifts can be achieved, but torque interruption occurs, clutch discs heat up and wear increases, fuel consumption increases, and the mechanism becomes heavy and occupies large space
Solution Approach 1:
The planetary gear mechanism acts as an intermediary between the internal combustion engine and the gearbox input shaft. During gear shifts, the planetary gear allows temporary disconnection of torque transmission paths while maintaining mechanical coupling, enabling smooth gear changes without complete torque interruption. The multiple gear pairs and coupling devices work together to redistribute torque flow through alternative paths.
Solution Approach 2:
The transmission system is divided into multiple independent gear pairs (first gear pair connected to first planetary gear, second gear pair connected to second planetary gear, third gear pair connected to range gearbox) that can be engaged and disengaged separately. This segmentation allows one gear pair to be shifted while others continue to transmit torque, maintaining overall torque continuity to the output shaft.
2Force
If both the internal combustion engine and the electrical machine are connected with the planetary gear to deliver increased torque during acceleration, then torque delivery capability is improved, but the maximum torque is limited by the electrical machine's strength and gear ratio
Solution Approach 1:
The system adds a second planetary gear and range gearbox dimension to the traditional single planetary gear arrangement. This creates multiple torque multiplication paths with different gear ratios. The first planetary gear provides one torque multiplication path, the second planetary gear provides another path, and the range gearbox provides additional gear ratio options, allowing the system to overcome the torque limits of individual components by distributing torque through multiple dimensional paths.
Solution Approach 2:
The system merges the torque output from two separate planetary gears and a range gearbox to deliver combined torque to the output shaft. The first planetary gear, second planetary gear, and range gearbox all contribute torque through their respective gear pairs, combining their capabilities to exceed the torque limit of any single component.
3Adaptability or versatility
If a large number of gear steps are required for heavy vehicles, then the gearbox can provide adequate gear ratios, but the number of components increases, resulting in increased size and weight
Solution Approach 1:
The range gearbox is nested within the existing planetary gear structure, with the input shaft of the range gearbox connected to the first planetary gear and the output shaft connected to the output shaft. This nested arrangement allows the range gearbox to add gear ratio options without requiring completely separate transmission systems, reducing overall size and weight while providing additional gear steps.
Data Source
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AI summary
The present invention relates to a method to control a hybrid powertrain to achieve a shift operation from a low range position to a high range position, wherein the hybrid powertrain (3) comprises an internal combustion engine (4); a gearbox (2) with an input shaft (8) and an output shaft (20); a range gearbox (11) connected to the output shaft (20); a first planetary gear (10), connected to the input shaft (8); a second planetary gear (12), connected to the first planetary gear (10); 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 (60, 72), connected with the first planetary gear (10) and the output shaft (20); and at least one gear pair (66, 78), connected with the second planetary gear (12) and the output shaft (20), wherein the internal combustion engine (4) is connected with the first planetary gear (10) via the input shaft (8). The method comprises the steps: a) engaging a gear by connecting two rotatable components (22, 26, 50) in the first planetary gear (10); b) connecting the second or the fourth gear pair (G2; 66; 78); c) connecting a sixth gear pair (G5, 125), arranged between a countershaft (18) and the range gearbox (11), to the countershaft (18), so that the countershaft (18) is connected with the output shaft (20) via the range gearbox (11); d) synchronising the rotational speed between two rotatable components (118, 114) in the range gearbox (11) with the assistance of a synchronising device (130); e) connecting the rotatable components (118, 114) with a shiftable third clutch device (128) and f) engaging a gear by way of connecting two rotatable components (28, 32, 51) in the second planetary gear (12).