Variable Displacement Oil Pump Guide Pin Thermal Deformation
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Solution Overview
Problem
Variable displacement oil pumps near heat sources experience thermal deformation of guide pins, leading to misalignment and reduced controllability of oil discharge due to contact with guide surfaces, causing the adjustable member to shift less in response to pressure changes.
Innovation Solution
The guide pin is fixed to either the housing or cover, with the long hole having a wider section farther from the fixed end, preventing contact with guide surfaces and allowing smooth shifting of the adjustable member, even when thermally deformed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guide pin is fixed to the housing with a uniform width long hole, then the guide pin provides stable guidance, but thermal deformation causes the guide pin to contact the guide surface and push the adjustable member, degrading controllability
Solution Approach 1:
The long hole is designed with different widths at different positions: a first width at the fixed end and a second width at the free end. This local variation in geometry allows the hole to accommodate thermal deformation of the guide pin while preventing contact with the guide surface, thus maintaining both guidance stability and adjustable member controllability under thermal conditions.
Solution Approach 2:
The width parameter of the long hole is changed along its length, creating a tapered or stepped structure. This parameter change enables the hole to compensate for thermal expansion of the guide pin, allowing the pin to deform without contacting the guide surface, thereby preventing unwanted pushing of the adjustable member.
2Temperature
If the guide pin is loosely fitted in the cover member, then thermal deformation can occur, but the guide pin may still contact the guide surface and cause misalignment
Solution Approach 1:
The long hole has a varying width profile with a larger second width at the free end compared to the first width at the fixed end. This local geometric variation provides clearance space for thermal deformation at the free end while maintaining precise alignment through the narrower fixed end, preventing contact with the guide surface.
Solution Approach 2:
The guide pin is nested within the long hole, which acts as a protective enclosure. The varying width of the long hole creates a clearance space that accommodates the guide pin's thermal expansion while preventing it from contacting the guide surface, thus maintaining alignment precision.
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 configuration maintains the controllability of oil discharge by preventing the guide pin from contacting the guide surfaces, ensuring the adjustable member can shift effectively in the extension direction, thus preventing degradation of oil discharge control.
Implementation Method 1
the guide pin may thermally deform as the variable displacement oil pump receives heat generated by the heat source and heat of oil suctioned through a suction port
Implementation Method 2
When the pressure inside the control oil chamber is changed through operation of the oil control valve, the adjustable member shifts in an extension direction of the long holes
Data Source
AI summary
A variable displacement oil pump includes an adjustable member that is configured to shift according to changes in pressure inside a control oil chamber. The adjustable member has a long hole. A guide pin is disposed inside the long hole. The guide pin is fixed to either a housing or a cover of the variable displacement oil pump. The width of the long hole is larger at a part of the long hole farther away from a fixed end of the guide pin in its lengthwise direction than at a part thereof closer to the fixed end.