Hydrostatic Planetary Transmission for Seamless Range Shifting
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Solution Overview
Problem
Existing speed change transmission apparatuses experience momentary power transmission interruptions and unstable speed changes, particularly during range skipping operations between speed ranges, due to misaligned clutch switchovers and varying drive loads, leading to inefficiencies and performance issues.
Innovation Solution
A speed change transmission apparatus utilizing a pair of planetary transmission mechanisms and strategically operated clutches to achieve seamless speed changes across multiple ranges, with a simplified construction that minimizes clutch switchovers and stabilizes power transmission by ensuring appropriate clutch engagement and disengagement, thereby maintaining consistent output across varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple clutches are used to achieve multiple speed ranges, then speed range versatility is improved, but clutch switchover complexity and power transmission stability deteriorate
Solution Approach 1:
The transmission system is segmented into multiple independent planetary transmission mechanisms (first, second, and third), each capable of providing different speed ranges. This segmentation allows the system to achieve versatility through modular combinations rather than relying on complex clutch switching, thereby maintaining power transmission stability.
Solution Approach 2:
Each planetary transmission mechanism is designed with multi-functionality, capable of operating in different engagement states to provide various speed ranges. The mechanisms can function independently or in combination, reducing the need for multiple clutches while maintaining versatility across different operating conditions.
2Adaptability or versatility
If multiple planetary transmission mechanisms are combined to achieve multiple speed ranges, then speed range versatility is improved, but device complexity increases
Solution Approach 1:
The planetary transmission mechanisms are arranged in a nested configuration where the second planetary transmission mechanism is positioned within the structure of the first, and the third is integrated with the second. This nesting reduces overall structural complexity while maintaining the ability to provide multiple speed ranges through coordinated operation.
Solution Approach 2:
Multiple planetary transmission mechanisms are merged into a single integrated transmission system sharing common components such as the input shaft and housing. This combining approach achieves speed range versatility without proportionally increasing device complexity, as the mechanisms work together as a unified system rather than separate units.
3Speed
If clutch switchovers are performed during range skipping operations, then speed range transitions are achieved, but momentary power transmission interruptions occur
Solution Approach 1:
The planetary transmission mechanisms are pre-configured with overlapping speed range capabilities, allowing the system to transition between ranges by smoothly adjusting the engagement state of mechanisms rather than through discrete clutch switchovers. This preliminary configuration ensures continuous power transmission during transitions.
Solution Approach 2:
The transmission system maintains continuous useful action during speed range transitions by ensuring that at least one planetary transmission mechanism remains engaged throughout the transition process. This continuous engagement eliminates momentary power transmission interruptions that would otherwise occur during clutch switchovers.
4Speed
If clutch operations are performed to change speed ranges, then speed control is achieved, but unstable speed changes occur due to varying drive loads
Solution Approach 1:
The transmission system employs dynamic engagement states of the planetary transmission mechanisms rather than fixed clutch operations. The mechanisms can continuously adjust their engagement levels in response to varying drive loads, maintaining stable speed changes even under changing operating conditions.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor drive load conditions and automatically adjust the engagement state of the planetary transmission mechanisms accordingly. This feedback control ensures stable speed changes by compensating for variations in drive loads in real-time, eliminating the instability caused by fixed clutch operations.
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 solution enables smooth, stepless speed changes in multiple ranges with reduced power interruptions and improved performance, even under changing drive loads, by optimizing clutch operations and using a compact, efficient planetary transmission design.
Implementation Method 1
a first planetary transmission mechanism (PF) and a second planetary transmission mechanism (PR)
Data Source
Figure 1
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AI summary
The apparatus includes a hydrostatic stepless speed change section (20) that has a hydraulic pump (23) and a hydraulic motor (24) and receives an output of an engine (1), a planetary transmission section (3a) having first and second planetary transmission mechanisms (P1, P2) and first and second output members (41, 42), and configured to combine a drive force outputted from the hydrostatic stepless speed change section (20) and an engine drive force that has not been subjected to any speed change action by the hydrostatic stepless speed change section (20), and a speed change output section (3b) having an output shaft 70, the speed change output section being configured to output combined drives force outputted from the output members (41, 42) in a plurality of different speed ranges from the output shaft 70. The output members are respectively coupled to the second sun gear and to either the second carrier or the second ring gear of the second planetary transmission mechanism. A power takeoff shaft is operatively coupled to the pump shaft.