Hydraulic Pump Piston-Shoe Assembly Without Crimped Weak Points
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Solution Overview
Problem
Existing methods for assembling and disassembling pistons and shoes in hydraulic pumps require deformation of the shoe, such as crimping, which can lead to weakness and failure, reducing durability and increasing assembly costs.
Innovation Solution
A method and assembly design that secures the piston to the shoe without crimping by inserting the piston shaft through the shoe aperture, using a plug to hold the piston head in place, and optionally adding a piston sleeve, allowing for different materials and sizes to enhance strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoe is crimped about the piston sphere to secure it in place, then the piston is secured to the shoe, but the crimped portions become points of weakness that can fail in use
Solution Approach 1:
The invention extracts the problematic crimping operation from the assembly process. Instead of crimping the shoe about the piston sphere, the design uses a through-bore aperture that allows the piston shaft to pass freely through the shoe, eliminating the crimped portions that become weak points while maintaining secure connection through the aperture design.
Solution Approach 2:
Instead of deforming the shoe material to secure the piston (crimping), the invention inverts the approach by creating an opening (aperture) through the shoe that accommodates the piston shaft. This reverses the traditional method of securing by deformation to securing by geometric constraint through the aperture design.
2Ease of manufacture
If the shoe is deformed to secure the piston, then the piston is retained in the shoe, but the assembly process becomes more complex and costly
Solution Approach 1:
The invention removes the complex shoe deformation process from the manufacturing sequence. By designing a through-bore aperture into the shoe, the assembly process is simplified to merely inserting the piston shaft through the aperture, eliminating the need for costly and complex crimping operations.
Solution Approach 2:
The aperture is pre-formed in the shoe during shoe manufacturing, allowing the piston shaft to be simply inserted during assembly. This preliminary preparation of the aperture eliminates the need for complex deformation operations during the assembly process itself.
3Ease of operation
If a through-bore aperture is used instead of crimping, then assembly is simplified, but the piston head must be retained by another mechanism
Solution Approach 1:
The invention uses a nested structure where the piston head is retained within the shoe by the geometric relationship between the piston head dimensions and the aperture dimensions. The piston head fits within the aperture opening, creating a retained assembly without requiring separate retention components.
Solution Approach 2:
The aperture is designed with asymmetric dimensions relative to the piston components - large enough to allow the piston shaft to pass through freely, but constrained such that the piston head cannot pass through. This asymmetric dimensional design provides automatic retention of the piston head while maintaining ease of assembly.
Data Source
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AI summary
A method of assembling a piston (200) and shoe (400) of a hydraulic pump, the method comprising: inserting a shaft (220) of the piston through an aperture (410) of the shoe (400) such that it extends through to the other side until a piston head (240) of the piston is seated in the shoe (400). A piston and shoe assembly (110) for a hydraulic pump, the assembly comprising: a piston (200) comprising a piston shaft (220) and a piston head (240); and a shoe (400) comprising an aperture (410), wherein the piston shaft (220) is sized such that it can pass through the shoe aperture (410) and the piston head (240) is sized such that it cannot pass through the shoe aperture (410).