Fuel Pump Lobe Design for Constant Velocity
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Solution Overview
Problem
High pressure fuel pumps in direct injection engines face challenges due to non-constant velocity profiles of the lobe-driven reciprocating members, which can affect the efficiency and consistency of fuel delivery.
Innovation Solution
A fuel pump drive system with a lobed drive shaft that includes a first lobe with a profile providing constant velocity for a portion of the compression stroke, ensuring consistent linear displacement of the reciprocating member and improved fuel pump operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional lobe profile is used to drive the fuel pump, then the fuel pump can be driven through the compression stroke, but the reciprocating member moves at non-constant velocity which reduces fuel delivery efficiency
Solution Approach 1:
The lobe profile parameters are specifically changed to create a constant velocity section. The lobe is designed with a constant radius section that corresponds to the desired constant velocity portion of the compression stroke, directly changing the geometric parameters to achieve the desired motion characteristic and improve fuel delivery efficiency
Solution Approach 2:
The lobe profile incorporates curved surfaces with specific radius variations. The constant radius section of the lobe creates a specific curvature pattern that translates rotational motion into constant linear velocity of the reciprocating member, while the varying radius sections provide acceleration and deceleration phases
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
The constant velocity profile enhances the efficiency and consistency of fuel delivery by maintaining a stable displacement and velocity during the compression stroke, improving the overall performance of the high pressure fuel pump.
Implementation Method 1
The lobe member may include a first lobe having a first opening flank driving a first compression stroke of the fuel pump through engagement with the reciprocating member
Implementation Method 2
The first lobe may have a profile providing a constant velocity for the linear displacement of the reciprocating member for a portion of the first compression stroke
Data Source
AI summary
A fuel system may include a fuel pump and a drive shaft. The fuel pump may include a reciprocating member and the drive shaft may include a lobe member engaged with the reciprocating member. The lobe member may linearly displace the reciprocating member and drive the fuel pump. The lobe member may include a first lobe having a first opening flank driving a first compression stroke of the fuel pump through engagement with the reciprocating member. The first lobe may have a profile providing a constant velocity for the linear displacement of the reciprocating member for a portion of the first compression stroke.