Fuel Pump Translating Cam Arrangement for Slip-Free Displacement Control
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Solution Overview
Problem
Existing fuel pumps experience uncommanded changes in displacement due to slippage between the cam sleeve and spacer ring, which complicates the determination of pump displacement and disrupts fluid flow timing.
Innovation Solution
A cam arrangement interfacing with a spacer ring through an involute gear set prevents slippage, ensuring precise determination of displacement by maintaining a fixed position of the cam arrangement relative to the spacer ring, even under high pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flat cam rolling surface with an anti-rotation pin is used to allow the cam sleeve to slide, then variable displacement capability is achieved, but slippage occurs during full stroke movement resulting in uncommanded displacement changes
Solution Approach 1:
The patent replaces the flat cam rolling surface with a curved cam surface. The cam sleeve follows a predetermined curved path relative to the rotor, which eliminates slippage during full stroke movement while maintaining variable displacement capability. The curvature of the cam surface ensures continuous rolling contact without the sliding that causes uncommanded displacement changes.
2Stability of the object's composition
If the cam ring is rigidly fixed to the pump housing, then structural stability is improved, but the pump loses variable displacement capability
Solution Approach 1:
The patent makes the cam ring dynamic by allowing it to rotate relative to the pump housing while maintaining structural stability through the curved cam surface geometry. The cam ring's position is controlled by the curved cam profile, enabling variable displacement adjustment while the overall structure remains stable. This dynamic configuration allows the pump to change displacement while maintaining structural integrity.
3Productivity
If the cam sleeve is allowed to slide freely towards full stroke, then maximum displacement is achieved, but slippage occurs causing uncommanded displacement changes
Solution Approach 1:
The curved cam surface guides the cam sleeve along a predetermined path that eliminates slippage even at full stroke positions. The geometry of the curved surface ensures that the cam sleeve achieves maximum displacement while maintaining precise, slip-free contact throughout the entire range of motion, enabling accurate displacement determination at all positions.
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 involute gear set ensures accurate control of pump displacement and fluid flow timing by preventing slippage, allowing the pump controller to determine displacement accurately and maintain consistent fluid flow.
Implementation Method 1
the cam arrangement interfaces with a spacer ring at an involute gear set that prevents slippage therebetween
Implementation Method 2
the involute gear set includes a rack and pinion gear set
Data Source
Figure 1
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Figure 3~5
AI summary
A fuel pump includes a cam arrangement surrounding a rotor and disposed within a spacer ring. The cam arrangement is configured to deterministically translate relative to the spacer ring and the rotor during stroking of the pump. An involute gear set provides an interface between the cam arrangement and the spacer ring. In some cases, the involute gear set is configured to provide a linear translation of the cam arrangement along a timing line. In other cases, the involute gear set is configured to provide a linear translation of the cam arrangement at an angle relative to the timing line.