Power-Split Transmission Layout for Faster Tractor Gear Shifts
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Solution Overview
Problem
Existing mechanical hydraulic power split continuously variable gearboxes in tractors face large swinging angle adjustments of hydraulic pumps during gear shifting, leading to prolonged shift times.
Innovation Solution
A power split transmission system incorporating a hydrostatic transmission mechanism, multiple planetary gear trains, and clutches to reduce the swinging angle range of the hydraulic pump, allowing for efficient gear shifting with reduced shift times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-plate clutch is used as the first coupling device and a multi-plate friction brake is used as the second coupling device, then the transmission system can achieve continuous and stepless power split ratio adjustment, but the structure becomes complex and the number of components increases
Solution Approach 1:
The patent combines the first coupling device (multi-plate clutch) and second coupling device (multi-plate friction brake) into a single integrated coupling mechanism. The control unit simultaneously controls both coupling devices to achieve continuous power split ratio adjustment without requiring separate independent control systems, thereby reducing overall system complexity while maintaining adaptability.
Solution Approach 2:
The integrated coupling mechanism serves multiple functions: it acts as both a clutch (first coupling device) and a brake (second coupling device) within a single structural framework. This multi-functionality allows the system to achieve continuous power split adjustment across different operating conditions without requiring multiple specialized components.
2Adaptability or versatility
If the first and second coupling devices are controlled independently, then the power split ratio can be adjusted continuously, but the control system complexity increases
Solution Approach 1:
The control unit merges the control functions of both coupling devices into a single integrated control system. By receiving a single operation signal and simultaneously controlling both the multi-plate clutch and multi-plate friction brake, the system achieves continuous power split ratio adjustment without requiring two independent control systems, thereby reducing control complexity.
3Device complexity
If conventional transmission systems are used for electric hybrid vehicles, then the structure is simple, but the system cannot meet the diverse power combination requirements of electric hybrid drive cycles
Solution Approach 1:
The patent implements a dynamic power split transmission system where the power split ratio can be continuously adjusted based on real-time operating conditions. The first and second coupling devices are dynamically controlled to achieve different power combination modes (series-parallel, parallel, series) according to the electric hybrid drive cycle requirements, transforming a static conventional transmission into a dynamic adaptive system.
Solution Approach 2:
The system changes the power split ratio parameter continuously to adapt to different power combination requirements. By varying the engagement states and torque transmission characteristics of the multi-plate clutch and multi-plate friction brake, the system can achieve different operational modes (series-parallel hybrid, parallel hybrid, series hybrid) to meet diverse electric hybrid drive cycle demands.
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
The system achieves faster gear shifts by minimizing the hydraulic pump's swinging angle range, improving overall performance and reducing dependence on the hydrostatic transmission mechanism, while maintaining a wide speed adjustment range.
Implementation Method 1
a mechanical hydraulic power split transmission mode is adopted, which can ensure that an engine changes a vehicle speed at a constant rotational speed by adjusting the output rotational speed of a hydrostatic transmission mechanism
Implementation Method 2
The planetary carrier of the first planetary gear train is coaxially fixed to the planetary carrier of the second planetary gear train. The planetary carrier of the first planetary gear train is coaxially fixed to the sun gear of the third planetary gear train.
Data Source
Figure 1
AI summary
Provided are a power split transmission system and a vehicle. A hydrostatic transmission mechanism (12, 13) of the power split transmission system is in driving connection to the sun gear of the first planetary gear train (2) and the sun gear of the second planetary gear train (3). The planetary carrier of the first planetary gear train (2) is connected to the planetary carrier of the second planetary gear train (3). The planetary carrier of the first planetary gear train (2) is connected to the sun gear of a third planetary gear train (4). The planetary carrier of the third planetary gear train (4) is in transmission connection to an input main shaft (1). A first clutch (5) can make the input main shaft (1) connected to the gear ring of the second planetary gear train (3) in a forward rotation manner. A second clutch (6) can make the input main shaft (1) connected to the gear ring of the second planetary gear train (3) in a reverse rotation manner. A brake (7) can lock the gear ring of the first planetary gear train (2). The driving plate of a third clutch (10) is in transmission connection to the gear ring of the third planetary gear train (4). The driving plate of a fourth clutch (11) is in transmission connection to the sun gear of the third planetary gear train (4). Each of the driven plate of the third clutch (10) and the driven plate of the fourth clutch (11) is connected to an output main shaft (9). The transmission system implements a large speed adjustment range, reduces the transmission dependence of hydrostatic transmission, and reduces gear shift time.