Hydrostatic Transaxle Housing Segmentation for Cost Reduction
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Solution Overview
Problem
Conventional hydrostatic transaxles (IHTs) face challenges in economizing the housing structure and compactness, as both housing members must support the hydrostatic transmission and deceleration drive train, leading to material inefficiency and complexity in the center section design.
Innovation Solution
The design separates the housing members such that only the first housing member supports the hydrostatic transmission and deceleration drive train, allowing the second housing member to be made of inexpensive materials like plastic or synthetic resin, and optimizes the center section by compactly arranging the pump control arm and motor gear to reduce interference and simplify fluid passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If both housing members support the HST and deceleration drive train, then structural strength is ensured, but material cost increases and housing economy is reduced
Solution Approach 1:
The housing is segmented into two functional zones: the first housing member supports the HST and deceleration drive train, while the second housing member serves as a protective cover without bearing structural loads. This segmentation allows the second housing member to be made from inexpensive materials like plastic or synthetic resin, while the first housing member uses stronger materials only where needed for support.
2Volume of moving object
If the center section is narrowed to improve compactness, then space efficiency increases, but the arrangement of pump control arm and motor gear becomes more difficult
Solution Approach 1:
The pump control arm and motor gear are arranged in different spatial dimensions and orientations within the center section. The pump control arm is positioned and oriented such that it does not interfere with the motor gear, even in the narrowed center section. This dimensional arrangement allows compact packaging while maintaining functional independence of components.
3Volume of moving object
If the pump control arm is positioned adjacent to the motor gear, then space is utilized efficiently, but interference between components occurs
Solution Approach 1:
The pump control arm and motor gear are positioned asymmetrically within the center section. The pump control arm is offset and oriented at an angle relative to the motor gear, creating non-interfering spatial relationships. This asymmetric arrangement maximizes space utilization while preventing mechanical interference between the control arm and gear components.
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 approach reduces material costs by utilizing less expensive materials for the second housing member and achieves a more compact and efficient design by minimizing the load on the second housing member and simplifying the machining process for fluid passages.
Implementation Method 1
a hydrostatic transmission (HST), an axle, a deceleration drive train, wherein the HST includes a hydraulic pump and a hydraulic motor fluidly connected to the hydraulic pump
Data Source
AI summary
A hydrostatic transaxle (IHT) comprises a hydrostatic transmission (HST), an axle, a deceleration drive train, a first housing member, and a second housing member. The HST includes first and second hydraulic displacement units fluidly connected to each other. The first hydraulic displacement unit has a pump shaft for receiving power from a prime mover. The second hydraulic displacement has a motor shaft. The deceleration drive train is interposed between the motor shaft and the axle. The first housing member supports the HST and the deceleration drive train, and has an opening through which the HST and the deceleration drive train are installed into the first housing member. The second housing member is joined to the first housing member so as to serve as a lid for covering the opening of the first housing member after the HST and the deceleration drive train are installed in the first housing member so as to be supported by the first housing member.