Hybrid Gear Unit Tractive Force Interruption-Free Shifting
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Solution Overview
Problem
Existing automatic shift gear units for hybrid vehicles face challenges in load-shiftable operation during range changes, leading to tractive force interruptions and inefficiencies in torque distribution between combustion and electric engines.
Innovation Solution
A gear unit design featuring two parallel partial gears with a countershaft and two planetary gears, including a range group connected to the main gear, allows for seamless shifting between fast and slow ranges through a fifth shifting element that couples the ring gear with the output shaft or locks it, enabling tractive force support and reducing drag losses by adjusting the countershaft speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional automatic shift gear unit is used for hybrid vehicles, then the gear shifting function is provided, but tractive force interruptions occur during range changes
Solution Approach 1:
The gear unit is divided into two parallel partial gears (first and second partial gears) with separate gear input shafts, allowing independent operation of combustion engine and electric drive. This segmentation enables one partial gear to maintain tractive force while the other undergoes range changing, thus preventing tractive force interruptions.
Solution Approach 2:
The countershaft acts as an intermediary element that receives torque from both partial gears and transmits it to the output shaft. During range changes, the countershaft allows torque redistribution between the partial gears, enabling seamless transition without interrupting the tractive force delivered to the output shaft.
2Speed
If the fifth shifting element couples the ring gear with the output shaft, then fast range is achieved, but drag losses increase due to countershaft speed
Solution Approach 1:
The system dynamically adjusts the operational state of the fifth shifting element based on driving conditions. When transitioning from fast range to slow range, the fifth shifting element is brought into engagement to couple the ring gear with the output shaft, enabling the countershaft to rotate at higher speeds appropriate for the fast range, thereby optimizing power transmission while managing drag losses through controlled engagement.
3Speed
If the fifth shifting element locks the ring gear in a housing-fixed manner, then slow range is achieved, but tractive force distribution between engines becomes inefficient
Solution Approach 1:
The fifth shifting element periodically engages and disengages to switch between slow and fast ranges. During range changes, it temporarily locks the ring gear in a housing-fixed manner to establish the slow range configuration, then disengages to allow the ring gear to rotate freely, enabling efficient torque distribution between combustion engine and electric drive for optimized productivity.
Data Source
AI summary
A method for tractive force interruption-free shifting of a hybrid drive comprising combustion engine (21), electric engine (2), main gear (HG) comprising two parallel connected partial gears, output shaft (3), and first and second planetary gears (PG1, PG2). Each partial gear having either first hollow gear input shaft (4) or second solid gear input shaft (5). The first planetary gear (PG1) is connected to the main gear (HG) as the range group, with main gear (HG) comprising at least five gear planes (R1-R5) and at least four shifting elements (S1-S4). The electric engine (2) is connected to carrier (ST1) of the range group (PG1) and the output shaft (3) so that the electric engine (2) supports tractive force while the range group (PG1) is shifted, and the fifth gear plane (R5) is connected to carrier (ST1) of range group (PG1) and thus can be shifted under load.