Hydromechanical Transmission Synchronizing Assemblies
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Solution Overview
Problem
Existing hydromechanical transmissions face challenges with multi-disc clutches being costly, complex, and generating losses when not engaged, while dog clutches are sensitive to shift conditions and require perfect synchronization.
Innovation Solution
A hydromechanical transmission system incorporating a planetary arrangement with synchronizing assemblies and engaging means that allows for smooth and uninterrupted power flow by selectively engaging and disengaging clutches to achieve a broader speed range, using a method that synchronizes speed and connects the combined output with output members to alternate clutches for gear ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multi-disc clutches are used for range shifting, then flexible engagement strategies and smooth shifting are achieved, but cost, complexity, and losses increase
Solution Approach 1:
The transmission system is divided into two independent ranges: a hydrostatic range using a variable displacement motor for continuous speed variation, and a mechanical range using fixed gear ratios. This segmentation allows each subsystem to be optimized independently, reducing overall complexity while maintaining smooth operation capabilities in the hydrostatic portion.
Solution Approach 2:
The complex multi-disc clutch system is replaced by extracting only the essential function of range shifting. A simple dog clutch is used solely for discrete range changes, while continuous speed control is achieved through the hydrostatic motor, eliminating the need for complex clutch assemblies.
2Device complexity
If dog clutches are used for range shifting, then cost and complexity are reduced, but sensitivity to shift conditions and synchronization requirements increase
Solution Approach 1:
The transmission operates in segmented modes: hydrostatic mode for continuous speed control where synchronization is not required, and mechanical mode for discrete range changes. This segmentation allows the dog clutch to be used only when appropriate, reducing sensitivity issues.
Solution Approach 2:
The dog clutch is designed with preliminary engagement features including synchronization gears and interlocking teeth that engage only when speed differential is minimal. This preliminary action ensures reliable engagement without requiring perfect synchronization conditions.
3Productivity
If multiple clutches are used for range changes, then continuous variable transmission is maintained, but losses increase when clutches are not engaged
Solution Approach 1:
The transmission separates continuous speed control (hydrostatic range) from discrete range changes (mechanical range). The hydrostatic motor provides continuous variable transmission without clutches, eliminating clutch losses during normal operation. Clutches are engaged only briefly during range transitions.
Solution Approach 2:
The hydrostatic motor maintains continuous useful action for speed control without interruption by clutch operations. The mechanical range provides continuous action for torque multiplication, ensuring that at least one transmission path is always active and loss-free.
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 provides synchronous range shifting with low losses and low complexity, enabling smooth power flow from rest to maximum speed, maintaining engine efficiency across varying transmission speeds.
Implementation Method 1
a hydrostatic transmission coupled to the input member
Implementation Method 2
first, second, and third synchronizing assemblies rotatably connected to the first and second output members, and the planetary output shaft, respectively
Data Source
AI summary
A hydromechanical transmission having an input member, a hydrostatic transmission, and a mechanical transmission. The mechanical transmission includes first and second synchronizing assemblies for synchronizing at least one of a first or second output member with a combined output speed from the input member and the hydrostatic transmission. First and second clutch assemblies alternately engage to transfer power from the synchronized output member to a final drive.