Lightweight Roller Tappet for High-Pressure Fuel Pump
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Solution Overview
Problem
Existing multi-part roller tappets for high-pressure fuel pumps face challenges in maintaining external geometry and dimensions when securing a cup-shaped sleeve, requiring costly modifications and increased mass due to thick wall thickness, which affects adaptability and thermal deformation resilience.
Innovation Solution
A multi-part roller tappet design featuring a guide cylinder with a cylindrical constriction groove and a radially outward-facing radial ring, allowing for adjustable length and secure axial positioning of the cup-shaped sleeve, with a lightweight guide cylinder and precise inner surface machining for accurate fit and reduced tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the guide cylinder has a large wall thickness to avoid deformation when pressing the cup-shaped sleeve, then the structural integrity is improved, but the roller tappet mass increases which is disadvantageous
Solution Approach 1:
The guide cylinder is designed with non-uniform wall thickness: thicker walls at the constricted region to prevent deformation during sleeve pressing, and thinner walls in other regions to reduce overall mass. This local differentiation of wall thickness optimizes both structural integrity and weight reduction.
2Manufacturing precision
If the cup-shaped sleeve is secured in the guide cylinder, then the axial positioning accuracy is improved, but the external geometry and dimensions of the guide cylinder change which is disadvantageous
Solution Approach 1:
A constricted region is created locally in the guide cylinder wall where the cup-shaped sleeve is pressed in. This localized modification provides precise axial positioning of the sleeve while the rest of the guide cylinder maintains its original external geometry and dimensions, avoiding unwanted changes to the overall shape.
3Manufacturing precision
If the roller tappet is designed as an integral unit for a specific high-pressure fuel pump, then the manufacturing precision is improved, but the adaptability to various overall lengths and distances decreases and modifications are costly
Solution Approach 1:
The roller tappet is divided into separate components: the guide cylinder and the cup-shaped sleeve. This segmentation allows the cup-shaped sleeve to be pressed into the guide cylinder at different axial positions, enabling adaptation to various overall lengths and distances between camshaft and pump element while maintaining manufacturing precision through standardized pressing operations.
Solution Approach 2:
The design enables dynamic adjustment of the cup-shaped sleeve's axial position within the guide cylinder. By pressing the sleeve to different positions, the roller tappet can be adapted to different engine configurations and distances, providing versatility without requiring completely different integral designs for each application.
Data Source
AI summary
This disclosure relates to a roller tappet, in particular for a high-pressure fuel pump. The roller tappet is guided in a direction of a longitudinal axis thereof in a housing receptacle and is driven in the longitudinal direction by cams of a camshaft. The roller tappet has a tappet body. The tappet body has a tappet skirt, a pump piston contact seat, and a rotatably mounted roller, by means of which the roller tappet is supported on the camshaft. The tappet body has a guide cylinder, which is mounted in the housing receptacle and on which the roller is mounted, and a cup-shaped sleeve having the pump piston contact point, which cup-shaped sleeve is supported axially and radially in the guide cylinder.