Variable Displacement Oil Pump Cam Ring Control for Aeration Pressure Loss
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Solution Overview
Problem
Variable displacement oil pumps face issues with maintaining adequate operation pressure and achieving higher fluid pressure in internal combustion engines due to the generation of air voids (aeration) at high speeds, leading to decreased internal pressures in pumping chambers and inadequate cam ring movement.
Innovation Solution
The design incorporates a first control oil chamber to decrease pumping volume variation and a second control oil chamber to increase it, with a control mechanism that adjusts fluid discharge pressure to maintain higher operation fluid pressure in the cam ring, especially in high-pressure regions, ensuring the cam ring operates effectively despite aeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the variable displacement oil pump operates in high-speed region with conventional control mechanism, then the pumping volume variation increases, but the internal pressure of pumping chambers decreases due to aeration causing inadequate cam ring movement
Solution Approach 1:
The patent introduces a control mechanism that acts as an intermediary between the discharge pressure and the cam ring control system. This control mechanism includes a control piston that receives discharge pressure and transmits it to control the cam ring position, ensuring stable operation even when aeration occurs in the pumping chambers. The control mechanism mediates the pressure control function to prevent aeration-induced pressure loss from affecting cam ring movement.
2Adaptability or versatility
If the cam ring is allowed to move freely based on control oil chamber pressures, then the pumping volume can be adjusted, but the operation pressure becomes insufficient when aeration occurs in high-speed region
Solution Approach 1:
The patent applies local quality by creating distinct functional zones: the pumping chambers where aeration may occur, and the control mechanism that maintains stable pressure control. The control piston and control spring are positioned to provide localized pressure support independent of the pumping chamber conditions. This allows the cam ring to adjust pumping volume while the control mechanism ensures adequate operation pressure is maintained despite aeration in the pumping zones.
3Reliability
If the discharge pressure is increased to compensate for aeration, then the operation pressure can be maintained, but the control mechanism complexity increases
Solution Approach 1:
The control mechanism is designed with multi-functionality: the control piston serves both to transmit discharge pressure and to control cam ring position; the control spring provides both biasing force and pressure compensation; the control mechanism itself functions as both a pressure regulator and a displacement controller. By making these components multi-functional, the patent maintains adequate operation pressure without requiring additional separate control systems, thus limiting the increase in overall device complexity.
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 solution maintains adequate operation pressure and achieves higher fluid pressure in internal combustion engines, even in high-speed regions with aeration, by setting the operation fluid pressure higher than the control mechanism's pressure, thus ensuring the cam ring operates within the required pressure levels.
Implementation Method 1
a first control oil chamber to receive an operating fluid discharged from a discharge portion and thereby to produce an urging force to urge a movable member in a direction to decrease a pumping volume variation quantity of pumping chambers
Implementation Method 2
a second control oil chamber to receive the fluid discharged from the discharge portion and thereby to produce an urging force to urge the movable member in a direction to increase the pumping volume variation quantity
Implementation Method 3
a control mechanism operated before the pumping volume variation quantity becomes smallest, and arranged to discharge the fluid from the second control oil chamber or to supply the fluid to the second control oil chamber with increase in a discharge pressure
Data Source
AI summary
A variable displacement oil pump for an internal combustion engine includes a pump element to vary inside volumes of pumping chambers to suck and discharge an oil, a varying mechanism to vary a pumping volume variation quantity of the pumping chambers, with movement of a movable member such as a cam ring, an urging mechanism to urge the movable member in a direction to increase the pumping volume variation quantity, first and second control oil chambers to urge the movable member to vary the pumping volume variation quantity, and a control mechanism, such as a pilot valve, to control the supply/drainage of the oil to or from the second control oil chamber. An operation oil pressure of the movable member is set higher than an operation oil pressure of the control mechanism in a higher pressure region.