Hydrostatic Manual Transmission Neutral Position Latching
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Solution Overview
Problem
Existing transmission arrangements for travel drives, such as those in mobile construction and agricultural machines, face high wear and maintenance costs due to friction-based synchronization of shaft speeds in manual transmissions.
Innovation Solution
A transmission arrangement with a hydrostatic transmission and a manual transmission in series, featuring a hydraulically actuated coupling device that can be fixed in a neutral position, eliminating the need for friction elements by synchronizing shaft speeds through hydraulic adjustments, and incorporating a latching mechanism for mechanical fixing and hydraulic actuation via a piston and cylinder system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If friction elements are used for synchronizing shaft speeds in manual transmission, then speed synchronization is achieved, but wear and maintenance costs increase
Solution Approach 1:
The patent replaces the mechanical friction-based synchronization system with a hydrostatic transmission system. The hydrostatic transmission uses fluid pressure to synchronize shaft speeds without direct mechanical contact between synchronization components, thereby eliminating wear from friction elements while maintaining effective speed matching between input and output shafts.
Solution Approach 2:
The patent employs a hydrostatic transmission circuit that uses hydraulic fluid under pressure to control the synchronization of shaft speeds. The hydraulic system transmits force and motion through the fluid, enabling speed matching without the need for friction-based mechanical synchronizers, thus eliminating wear and maintenance issues associated with friction elements.
2Adaptability or versatility
If a coupling device is provided for changing gear stages, then gear shifting is enabled, but the device complexity increases
Solution Approach 1:
The patent combines the coupling device functionality with the hydrostatic transmission system. The same hydraulic circuit that provides power transmission also controls the coupling device for gear stage changes. This merging of functions reduces the number of separate control systems and simplifies the overall device structure while maintaining the ability to change gear stages.
Solution Approach 2:
The hydrostatic transmission system serves multiple functions: it provides power transmission, controls shaft speed synchronization, and actuates the coupling device for gear stage changes. This multi-functionality reduces the need for separate dedicated systems for each function, thereby reducing overall device complexity while maintaining adaptability for gear stage changing.
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 solution reduces wear and maintenance costs by eliminating friction elements, allowing for efficient speed synchronization and torque control, thereby enhancing the efficiency and reliability of the transmission system.
Implementation Method 1
a hydrostatic transmission (4) with two hydraulic machines (8, 14) in a hydraulic circuit (10, 12)
Implementation Method 2
its friction surface or friction element comes into contact with a friction surface or a friction element of the loose wheel of the gear to be engaged is acted upon. The rotational speed of the transmission input shaft is adapted (synchronized) to the rotational speed of the driving situation (transmission output shaft) via the transmitted frictional forces
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A transmission arrangement is disclosed comprising a hydrostatic transmission and a series-coupled manual transmission with two interchangeable gear stages, via which an input shaft of the manual transmission can be brought into a geared rotary connection with its output shaft, wherein a hydraulically actuated coupling device is provided for changing the gear stages, wherein the transmission arrangement (3) is designed such that the coupling device (38) can be fixed in a neutral position (N) in which the geared rotary connection is released.