Hydrostatic Transaxle Charge Pump Nesting
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Solution Overview
Problem
Current hydrostatic transaxles face challenges in efficiently managing hydraulic fluid pressure and volume, particularly in neutral positions, leading to inefficiencies in drive apparatus performance.
Innovation Solution
A hydrostatic transaxle design incorporating a gerotor charge pump within a center section assembly, featuring a charge pump cover with a relief assembly that extends into the void volume of a ring gear, ensuring fluid circulation and pressure management through a closed loop system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional hydrostatic transaxle design is used, then the structure is simpler, but fluid pressure management is inefficient leading to performance loss
Solution Approach 1:
The charge pump is nested within the pocket of the center section housing, utilizing the existing void space. The relief assembly is integrated into the charge pump cover, creating a compact nested structure that manages fluid pressure without adding external components, thereby reducing energy loss while maintaining structural simplicity
Solution Approach 2:
The charge pump and relief assembly are merged into a single integrated unit within the center section. The charge pump cover assembly combines the pump housing with the relief valve mechanism, creating a unified component that improves fluid pressure management while minimizing the number of separate parts
2Volume of moving object
If the charge pump is placed outside the center section, then installation is easier, but the device occupies more space reducing compactness
Solution Approach 1:
The charge pump is nested within the pocket of the center section housing, utilizing the existing void space. This nesting approach minimizes the overall volume occupied by the charge pump while keeping it accessible for manufacturing and assembly operations
Solution Approach 2:
The charge pump is positioned in a pocket on one side of the center section, utilizing the lateral dimension rather than occupying additional axial or radial space. This dimensional arrangement maintains compactness while preserving ease of manufacture and assembly
3Productivity
If the relief assembly is positioned away from the void volume, then assembly is simpler, but fluid circulation efficiency is reduced
Solution Approach 1:
The relief assembly is extracted and positioned to extend directly into the void volume of the ring gear, separating the fluid circulation function from the charge pump body. This extraction allows the relief assembly to directly manage fluid pressure in the void volume, improving circulation efficiency while keeping the charge pump structure relatively simple
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 design enhances fluid circulation and pressure management, optimizing drive apparatus performance by maintaining hydraulic fluid flow and pressure balance, even in neutral positions, thereby improving efficiency and compactness.
Implementation Method 1
A gerotor charge pump is contained within a pocket on an opposing side of the center section
Implementation Method 2
A charge pump cover assembly secures the gerotor charge pump in the pocket and has a charge relief assembly that extends into a void volume defined by a ring gear of the gear reduction set
Data Source
AI summary
A transaxle for use as a drive apparatus of a vehicle is provided. The transaxle includes a main housing joined to a gear housing to enclose a transmission and a reduction gear set. The transmission includes a pump assembly and a motor assembly arranged in a parallel configuration on one side of a center section. A charge pump is contained within a pocket on an opposing side of the center section. A charge pump cover assembly secures the charge pump in the pocket and has a charge relief assembly that extends into a void volume defined by a ring gear of the gear reduction set. The gear reduction set drives an axle extending from the gear housing.