Variable Oil Pump Guide Pin Line Contact for Smooth Displacement
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Solution Overview
Problem
The existing variable oil pump's responsiveness in changing oil discharge is deteriorated due to the initial sticking of the guide pin's outer surface to the guide hole's inner surface, causing the adjustment ring to not start displacing smoothly.
Innovation Solution
A variable oil pump design featuring a guide portion with a groove and pin that come into line contact at the initial position, forming a small air gap to prevent sticking and allowing instantaneous separation, ensuring smooth rotation of the adjustment member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the arcuate inner surface of the guide hole comes into circumferential surface contact with the outer surface of the guide pin at the initial position, then the adjustment ring is securely held at the initial position, but the outer surface of the guide pin sticks to the inner surface of the guide hole due to oil in the guide hole, causing the adjustment ring to not start displacing smoothly
Solution Approach 1:
The patent applies local quality by changing the contact geometry from circumferential surface contact to line contact at specific locations. The guide hole is designed with a flat-bottomed groove structure where the guide pin contacts the groove at specific line contact points rather than along the entire circumferential surface. This localized contact approach maintains holding stability at the initial position while preventing oil film formation across the entire contact surface, thereby enabling smooth displacement when actuation force is applied.
2Ease of operation
If the inner surface of the groove and outer surface of the pin come into line contact at the initial position, then a small air gap is formed preventing sticking, but the adjustment member must be securely held at the initial position before displacement
Solution Approach 1:
The flat-bottomed groove structure creates localized line contact regions where the guide pin contacts the groove at specific points. The flat bottom portion of the groove provides a stable reference surface that ensures consistent line contact geometry, maintaining initial position stability while allowing the air gap to prevent oil film sticking. This localized contact approach resolves the contradiction between holding stability and displacement responsiveness.
3Device complexity
If circumferential surface contact is used between guide pin and guide hole, then structural simplicity is maintained, but responsiveness in changing oil discharge amount is deteriorated
Solution Approach 1:
The patent modifies the guide hole structure to include a flat-bottomed groove with specific geometric features that create line contact regions. While this increases structural complexity compared to a simple circular guide hole, it dramatically improves responsiveness by preventing oil film sticking. The added complexity is localized to the guide structure geometry, while the overall pump system remains relatively simple. This resolves the contradiction by accepting minimal structural complexity increase for significant productivity improvement.
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
This design improves the responsiveness of oil discharge amount changes by securely holding the adjustment member at the initial position and preventing rattling, enabling smooth displacement and rotation.
Implementation Method 1
a small air gap is formed between the inner surface of the groove and the outer surface of the pin such that it is possible to prevent the outer surface of the pin from sticking to the inner surface of the groove due to oil (the surface tension of a very thin oil film) in the groove
Implementation Method 2
prevent the outer surface of the pin from sticking to the inner surface of the groove due to oil (the surface tension of a very thin oil film) in the groove
Data Source
AI summary
A variable oil pump includes a pump housing, an oil pump rotor housed in the pump housing and rotationally driven, an adjustment member housed in the pump housing and adjusting an oil discharge amount from the oil pump rotor by being displaced due to a drive force while rotatably holding the oil pump rotor from an outer peripheral side, and a guide portion including a groove provided in the adjustment member and a pin provided on the pump housing and engaging with the groove. The guide portion guides relative displacement of the adjustment member with respect to the pump housing by engaging the groove and the pin with each other, and an inner surface of the groove and an outer surface of the pin come into line contact with each other along a direction in which the pin extends at an initial position where the adjustment member starts its displacement.