Single-Piece Tappet for Radial Piston Pump High-Pressure Reliability
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Solution Overview
Problem
Radial piston pumps in accumulator injection systems for internal combustion engines face challenges in withstanding high pressures and maintaining precise operation due to mechanical loads, requiring a design that minimizes friction and deformation while being cost-effective.
Innovation Solution
A plunger arrangement with a circular-cylindrical ram and a single-piece tappet design that integrates a roller mount and safety device, eliminating the need for separate components and allowing for precise, low-friction movement and secure axial positioning of the roller, thereby reducing production costs and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-part tappet design is used with separate roller shoes and plunger parts, then the structural complexity increases and production costs rise, but the reliability and precision of operation under high pressure are compromised due to potential deformation and chip formation at connection points
Solution Approach 1:
The patent merges the roller shoe and plunger body into a single integral tappet component. The roller is directly mounted on the tappet body without separate connection parts, eliminating the interface between roller shoe and plunger. This single-piece construction prevents deformation and chip formation at connection points, ensuring reliable operation under high pressures while simplifying the overall structure.
2Ease of manufacture
If multiple separate components are used for the tappet assembly, then the ease of manufacture decreases due to additional assembly steps and precision requirements, but the productivity is reduced due to increased assembly time and potential quality issues
Solution Approach 1:
The tappet is manufactured as a single piece through forging or casting, followed by direct mounting of the roller. This eliminates multiple assembly steps involving separate plunger parts and roller shoes, reducing assembly time and potential quality issues while maintaining manufacturing simplicity through standardized processes.
Solution Approach 2:
The roller is pre-mounted directly onto the tappet body during the initial manufacturing process rather than being assembled separately later. This preliminary action ensures precise positioning and secure fixation from the outset, eliminating the need for subsequent assembly operations and quality checks on connection interfaces.
3Reliability
If separate press-in parts are used to connect the roller to the tappet, then the device complexity increases, but harmful effects such as deformation and chip formation occur at the connection interfaces
Solution Approach 1:
The roller and tappet body are designed as an integrated unit where the roller is directly mounted on the tappet without separate press-in parts. This eliminates the connection interface that would otherwise be prone to deformation and chip formation, ensuring reliable force transmission from the roller to the tappet under high-pressure conditions.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A pushrod arrangement for a radial piston pump for conveying a fluid is designed for at least indirect support of a pump plunger on a drive shaft designed to drive the radial piston pump and has: a circular cylindrical pushrod (101) with a pushrod longitudinal axis (L); a roller (102), which is rotatably mounted in the pushrod (101) and can be coupled to the drive shaft; a clip (103) formed separately from the pushrod (101) and capable of being mechanically coupled to said pushrod (101), which clip is arranged and designed such that a movement of the roller (102) relative to the pushrod (101) in the direction of a roller longitudinal axis (R) is prevented, wherein the pushrod (101) is designed as a single piece and has an external face (104) which runs parallel to the pushrod longitudinal axis (L) to support said pushrod (101) in a housing of the radial piston pump; a holder (105) for the roller (102).