Hydrostatic Transmission Assembly With Internal Expansion Bladder
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Solution Overview
Problem
Hydrostatic transmissions for vehicles and equipment face challenges in fluid expansion and orientation versatility, requiring reliable fluid filling and air purging, especially when installed in orientations that make complete filling impractical.
Innovation Solution
The transmission assembly incorporates an internal expansion bladder that allows fluid expansion without venting to atmosphere, enabling orientation flexibility and eliminating the need for external expansion tanks, with a design that includes a sealing interface and rib structures to ensure proper sealing and controlled collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission uses an internal expansion bladder design, then orientation versatility is improved and external expansion tanks are eliminated, but the sealing interface complexity increases
Solution Approach 1:
The expansion bladder is nested within the transmission housing, creating a compact internal structure that eliminates the need for external expansion tanks while maintaining fluid expansion capability in any orientation
Solution Approach 2:
The expansion bladder utilizes a flexible membrane structure that can expand and contract internally without rigid connections, enabling orientation versatility while managing sealing requirements through the flexible material properties
2Reliability
If the transmission assembly is designed for complete fluid filling, then air purging reliability is improved, but manufacturing complexity increases when accommodating various orientations
Solution Approach 1:
The transmission is pre-filled with fluid at the manufacturing stage before sealing, ensuring complete filling and air purging is performed beforehand, which simplifies the manufacturing process while maintaining reliability across all orientations
Solution Approach 2:
The sealed internal design with expansion bladder allows the transmission to self-manage fluid expansion and contraction without requiring external filling or venting operations, maintaining reliability while simplifying manufacturing
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 allows for reliable operation in any orientation without the need for external venting or fluid filling, ensuring efficient fluid management and reducing manufacturing complexity, while maintaining the versatility of the transmission assembly.
Implementation Method 1
an internal expansion bladder that allows fluid expansion without venting to atmosphere
Data Source
AI summary
A drive device includes a housing forming a sump. A pump and motor are mounted on a center section having a porting system and a pair of ports with check plugs disposed therein. A bypass arm is engaged to one end of a bypass shaft external to the housing and rotates the bypass shaft to selectively cause engagement fingers to move each check plug to an open position. A housing projection is contacted by the bypass arm to selectively limit rotation thereof. The axes of rotation of a swash plate trunnion shaft, a pump input shaft and a motor output shaft may all be disposed in a single plane. The input shaft is supported by a housing bearing and an opening in the center section and is restrained from axial movement by the bearing and a thrust surface on the center section.