Dual Piston Accumulator with Variable Wall Thickness
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Solution Overview
Problem
Conventional dual piston accumulators used in hydrostatic hybrid drive systems are not compact enough and have excessive structural weight, failing to meet the requirements of modern automotive engineering for reduced size and weight.
Innovation Solution
A dual piston accumulator design with a one-piece accumulator housing that has varying wall thickness adapted to pressure levels, featuring a continuous inner cylinder without a shoulder, where both pistons have the same diameter and an intermediate piece is securely fastened to the thicker section, allowing for reduced weight and compactness through deep drawing or stamping processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional dual piston accumulator design is used, then structural strength is sufficient, but weight is excessive and compactness is poor
Solution Approach 1:
The housing wall thickness is varied locally according to pressure requirements: thicker walls in the high-pressure chamber region and thinner walls in the low-pressure chamber region. This local differentiation reduces overall weight while maintaining structural strength where needed.
Solution Approach 2:
The housing is designed as a one-piece deep-drawn component with continuous cylindrical inner surface, eliminating shoulders and steps. This dimensional optimization allows material to be distributed more efficiently, reducing weight while maintaining integrity.
2Volume of moving object
If conventional dual piston accumulator design is used, then functional separation is achieved, but compactness is poor
Solution Approach 1:
The high-pressure and low-pressure chambers are merged into a single one-piece housing structure without shoulders or steps. The continuous cylindrical inner surface eliminates the need for separate housing sections, reducing overall volume and simplifying the structure.
Solution Approach 2:
While the housing is unified, the functional segmentation is achieved through the intermediate piece that separates the high-pressure and low-pressure chambers. This allows functional separation without structural complexity.
3Loss of substance
If uniform wall thickness is used, then manufacturing is simple, but material usage is not optimal
Solution Approach 1:
The wall thickness is optimized locally: thicker in the high-pressure region to withstand higher stresses, and thinner in the low-pressure region where less material is needed. This local quality differentiation improves material efficiency.
Solution Approach 2:
The wall thickness parameter is changed along the length of the housing to match the pressure distribution. This parameter optimization reduces material usage while maintaining structural integrity under varying pressure conditions.
Data Source
AI summary
A dual piston accumulator, in particular for a hydrostatic hybrid drive system for vehicles, replaces a high pressure hydro accumulator and a low pressure hydro accumulator. Inside a single accumulator housing (2) extending in the axial direction in a single piece over a high pressure part (4) and a low pressure part (6), an accumulator piston (8, 10) defines a high pressure-sided fluid chamber (16) and a low pressure-sided fluid chamber (18). Both chambers border an intermediate piece (12) separating the high pressure side (4) from the low pressure side (6). A common piston rod (14) extends through the intermediate piece for both accumulator pistons (8, 10). The wall width of the housing (2) corresponding to the high pressure part (4) is greater than the opposite reduced wall width corresponding to the low pressure part (6).