Power Split Transmission With Reversing Gear And Shifting Mechanism
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Solution Overview
Problem
Power split transmissions in working machines, such as wheel loaders, face challenges in providing multiple operating ranges without complex control mechanisms and ensuring continuous tractive force during gear shifting.
Innovation Solution
A power split transmission design featuring a reversing gear upstream of the summation gear, with hydrostatic and mechanical branches, and a gear shifting mechanism that allows for two operating ranges in each direction by adjusting hydrostatic units via a common component, enabling seamless gear shifting without interrupting tractive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a power split transmission provides multiple operating ranges without complex control mechanisms, then the device complexity is reduced, but the ability to provide multiple operating ranges in both forward and reverse directions is limited
Solution Approach 1:
The transmission is divided into distinct operating ranges (first and second operating ranges in both forward and reverse directions) with specific clutch engagement patterns for each range, allowing multiple operating modes without requiring complex continuous control mechanisms
Solution Approach 2:
The same hydrostatic unit and clutch arrangements are used to achieve multiple operating ranges in both forward and reverse directions, allowing a single transmission system to perform multiple functions without requiring separate control mechanisms for each direction
2Productivity
If gear shifting is performed in a standard transmission, then the gear ratio changes, but the tractive force is interrupted during the shifting process
Solution Approach 1:
During gear shifting from first to second operating range, the hydrostatic unit maintains continuous engagement and provides continuous tractive force while the clutch transitions between engagement states, eliminating interruptions in the useful action of driving the vehicle
Solution Approach 2:
The hydrostatic unit acts as an intermediary between the engine and the mechanical transmission during gear shifting, absorbing torque fluctuations and maintaining continuous power transmission while the mechanical clutches engage and disengage
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
Enables simple control of the hydrostatic power branch and allows for smooth shifting between operating ranges without interrupting tractive force, optimizing power transfer and reducing mechanical stress.
Implementation Method 1
The first and second hydrostatic units have a common component, by means of which the displacements of the first and of second hydrostatic units can be adjusted simultaneously
Data Source
AI summary
A power split transmission for a working machine, such as a wheel loader, for example, has a hydrostatic and a mechanical power branch which are summed with one another via a summation gear (12). A reversing gear (7) is connected downstream of the summation gear (12) and a gear shifting mechanism (20) is connected downstream of the summation gear (12).