Valve Timing Control Apparatus Managing Hydraulic Shear
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Solution Overview
Problem
Existing valve timing control apparatuses face challenges in ensuring engine startability, particularly at low temperatures, due to increased hydraulic fluid viscosity, which hinders the movement of limiting members into recesses, leading to potential interference and tilting issues, and manufacturing tolerances causing misalignment and shearing resistance.
Innovation Solution
A valve timing control apparatus with a primary and secondary limiting member, resilient members, and strategically designed slide gaps to facilitate timely and accurate movement of the primary limiting member into recesses, ensuring engine startability by managing hydraulic fluid pressure and reducing shearing resistance through relative slide gaps and resilient forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic fluid is supplied into the working chamber to move the limiting member into the recess, then the limiting member can be moved into the recess, but the high viscosity of the hydraulic fluid at low temperatures increases shearing resistance and prevents timely movement
Solution Approach 1:
The patent divides the single limiting member into two separate limiting members (first and second), each capable of independently limiting rotational phase. This segmentation allows the system to function reliably even if one limiting member fails to move timely due to high fluid viscosity, as the other can still perform the limiting function to ensure engine startability.
Solution Approach 2:
The patent introduces hydraulic fluid pressure into the working chamber before the engine start period begins, performing the action of moving the limiting members into the recess in advance. This preliminary action ensures that the limiting members are already in position when the engine needs to start, eliminating the problem of delayed movement due to high viscosity during the critical start period.
2Reliability
If the limiting member is moved into the recess during engine start period, then the rotational phase can be limited to ensure startability, but the remaining hydraulic fluid in the working chamber creates resistance against the limiting member movement
Solution Approach 1:
By segmenting the limiting function into two separate limiting members, the patent reduces the force required to move each individual member. Each member experiences less resistance and can be moved more easily into the recess, overcoming the shearing resistance caused by remaining hydraulic fluid during the engine start period.
Solution Approach 2:
The patent applies hydraulic fluid pressure excessively (above normal operating pressure) to move the limiting members into the recess during the engine start period. This excessive action overcomes the resistance from remaining hydraulic fluid by applying sufficient force to push the limiting members into position despite the high shearing resistance.
3Ease of manufacture
If manufacturing tolerances are present in the limiting member and recess, then production is easier and cost-effective, but misalignment occurs causing interference and tilting issues
Solution Approach 1:
The patent uses two separate limiting members instead of one, which compensates for manufacturing tolerances and misalignment. If one limiting member is slightly misaligned or tilted due to tolerance variations, the other limiting member can still function properly to ensure reliable rotational phase limiting and engine startability.
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 apparatus ensures reliable engine startability across varying temperatures by effectively managing hydraulic fluid pressure and reducing interference, allowing for quick and precise movement of limiting members, thus maintaining optimal valve timing.
Implementation Method 1
a primary resilient member and a secondary resilient member... The primary resilient member urges the primary limiting member in the inserting direction... The secondary resilient member urges the secondary limiting member in the inserting direction
Implementation Method 2
when the engine is instantaneously stopped due to an abnormality... the pressure, which is introduced into the working chamber, is reduced... the secondary limiting member... is urged by the corresponding secondary resilient member and is thereby moved into the recess
Data Source
AI summary
A primary resilient member urges a primary limiting member into a recess in an inserting direction in a state where a rotational phase is a limited phase in a limited phase range. A relative slide gap is radially provided between the primary limiting member and a secondary limiting member at a location adjacent to a working chamber. First and second primary slide gaps are radially provided between the primary limiting member and radially opposed wall surface sections of the receiving hole. A secondary slide gap is radially provided between the secondary limiting member and a radially opposed wall surface section of the receiving hole. The relative slide gap is larger than the first and second primary slide gaps and the secondary slide gap.