Fuel Pump Stopper Member Prevents Cam Lift-Off
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Solution Overview
Problem
High pressure fuel pumps experience loss of roller/cam contact around Top Dead Centre (TDC), leading to damage of the cam track and roller surfaces, exacerbated by increased pressure, speed, or pumping volume.
Innovation Solution
A fuel pump design incorporating a stopper member with resilient properties, made of composite plastic or deformable gas-filled cartridge, engaged around the piston to provide additional biasing force to the follower assembly at TDC, while remaining passive at Bottom Dead Centre (BDC), ensuring consistent contact with the cam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If regular increase in pressure, increase in rotational speed, or increase in pumping volume is implemented, then productivity and power are improved, but the risk of roller/cam lift-off increases causing surface damage
Solution Approach 1:
The stopper member is pre-positioned around the piston to provide preliminary support to the follower assembly. Before the cam can cause lift-off at high speeds, the stopper member is already in place to prevent separation, acting in advance to secure reliable contact between roller and cam surface during high-productivity operation
Solution Approach 2:
The stopper member acts as an intermediary element between the piston and the follower assembly. It mediates the interaction by providing additional biasing force when needed, allowing the system to maintain roller/cam contact stability even when operating at increased pressure, speed, or pumping volume
2Reliability
If spring biasing force is increased to maintain roller/cam contact, then contact stability is improved, but device complexity and space requirements increase
Solution Approach 1:
The stopper member serves multiple functions: it acts as a structural support element around the piston, provides conditional additional biasing force when the follower assembly approaches lift-off, and maintains a compact form factor. This multi-functionality improves contact stability without significantly increasing device complexity
Solution Approach 2:
The stopper member is designed as a thin-walled tubular structure that is resilient but not overly rigid. This flexible shell structure provides the necessary support function while maintaining a compact design that does not substantially increase the overall size or complexity of the follower assembly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents loss of contact between the roller and cam, reducing wear and enhancing the pump's operational reliability under increased pressure and speed conditions.
Implementation Method 1
a stopper member having resilient properties and being arranged to generate additional biasing force onto the follower assembly when around TDC
Implementation Method 2
a spring compressed between the pump head member and the follower assembly in order to permanently bias the follower assembly against the cam
Data Source
Figure 1~2
AI summary
A fuel pump (10) having a head member (12) provided with a blind bore (14) in which a piston (26) is adapted to perform a pumping cycle by reciprocating along the main axis (X1) of the bore (14) between a top dead center (TDC) position and a bottom dead center (BDC) position. The piston (26) reciprocates under the influence of a rotating cam (36) cooperating with a follower assembly (34), a spring (46) compressed between the head member (12) and the follower assembly (34biasing the follower assembly (34) toward the cam (36). The pump (10) further comprises a stopper member (48) having resilient properties and being arranged to generate additional biasing force onto the follower assembly (34) when around TDC.