High Pressure Pump Tappet Assembly Centering Guide
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Solution Overview
Problem
High-pressure pumps for fuel injection devices in internal combustion engines face issues with oblique press-in of the roller shoe into the tappet body due to manufacturing tolerances, leading to incorrect press-in or holding forces in the interference fit.
Innovation Solution
A centering guide is provided in the receptacle of the ram body to ensure accurate and robust press fitting of the roller shoe, preventing oblique pressing and enhancing the interference fit by automatically centering the roller shoe during press-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the roller shoe is pressed into the tappet body with high manufacturing tolerances, then the assembly process is easier, but the press-in forces become incorrect and the interference fit is compromised
Solution Approach 1:
The centering guide is provided in advance on the tappet body to establish a precise reference position before the roller shoe is pressed in. This preliminary centering feature ensures that the roller shoe is correctly positioned during the pressing operation, eliminating the need for extremely tight manufacturing tolerances while maintaining accurate press-in forces and a robust interference fit.
2Manufacturing precision
If very low manufacturing tolerances are used for the ram assembly components, then the interference fit is improved, but the assembly process becomes more difficult and costly
Solution Approach 1:
The centering guide enables the roller shoe to self-center during the pressing operation. The guide geometry automatically aligns the roller shoe with the tappet body bore, allowing the components to find their correct relative position without requiring extremely tight pre-manufactured tolerances. This self-centering mechanism simplifies the manufacturing process while ensuring accurate interference fit.
3Productivity
If the roller shoe is pressed in obliquely due to tolerance accumulation, then the assembly is faster, but the press-in forces are falsified and the interference fit is compromised
Solution Approach 1:
The centering guide acts as an intermediary element between the roller shoe and the tappet body bore. It mediates the pressing operation by providing a guiding surface that ensures axial alignment during insertion. This intermediary feature prevents oblique pressing while maintaining assembly speed, ensuring that the full press-in force is applied correctly to create a reliable interference fit without compromising the roller shoe or tappet body.
Data Source
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AI summary
The invention relates to a high pressure pump for a fuel injection device of an internal combustion engine, comprising at least one pump element having a pump piston delimiting a pump working chamber, wherein between the pump piston and a rotationally driven drive shaft of the high pressure pump, a tappet assembly having a tappet body and a roller shoe pressed into a receptacle of the tappet body is provided, wherein the tappet body comprises a centering guide for pressing in the roller shoe. The invention further relates to a tappet assembly for a high pressure pump for a fuel injection device of an internal combustion engine comprising a tappet body and a roller shoe pressed into a receptacle of the tappet body, wherein the tappet body comprises a centering guide for pressing in the roller shoe.