Segmented Cam Follower Tappet for Fuel Injection Pumps

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Solution Overview

Problem

Conventional cam follower roller devices have high inertia due to solid tappets, leading to energy losses, and deformation during spindle mounting can disrupt manufacturing tolerances, affecting sliding performance.

Innovation Solution

The cam follower roller device is designed with a tappet composed of two separate parts: a roller support body and a guide sleeve, where the shaft is fixed to the support body to reduce weight and prevent deformation, allowing for easier machining and assembly, and the guide sleeve is designed to allow lubricant passage for reduced friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the tappet is made as a solid single piece by cold forging, then the tappet has high strength and structural integrity, but the tappet has relatively high inertia leading to energy losses

Engineering Contradiction:

Improvetappet structural integrityVSAvoidenergy losses due to high inertia

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The tappet is divided into two separate parts: a support body and a guide sleeve. The support body contains the roller mounting features while the guide sleeve provides the sliding surface. This segmentation reduces the overall mass and inertia of the tappet assembly while maintaining the necessary structural strength and guidance functions separately.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the roller is mounted on the tappet by upsetting or crimping the spindle, then the roller is securely fixed, but the tappet becomes deformed and manufacturing tolerances are no longer met

Engineering Contradiction:

Improveroller mounting securityVSAvoidtappet dimensional tolerances

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By separating the tappet into a support body and guide sleeve, the deformation caused by spindle mounting is confined to the support body only. The guide sleeve remains undeformed and maintains its manufacturing tolerances for the sliding surface, ensuring precise operation despite the deformation in the support body.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the tappet is made as a solid single piece, then the manufacturing process is relatively simple, but the overall weight of the tappet is high

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidtappet weight

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The tappet is segmented into a support body and guide sleeve that can be manufactured separately using optimized processes for each component, then assembled together. This allows weight reduction through selective material usage and thinner wall sections in the guide sleeve, while maintaining manufacturing feasibility through standard machining and assembly operations.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9032863B2Cam follower roller device, notably for a fuel injection pump

Publication Date: 2015.05.19 AB SKF SKF PATENT DEPARTMENT

AI summary

Cam follower roller device, notably for an internal combustion engine fuel injection pump, comprising a tappet (12) and a roller (14) mounted to rotate on the tappet and intended to press against a cam. The tappet (12) comprises a roller support body (16), a shaft (26) for mounting the roller on the said body, and a guide sleeve (18) attached to the support body and at least partially surrounding the said body. The ends of the shaft are fixed in through-holes in the support body.