Variable Valve Device Rocker Arm Inclination Control
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Solution Overview
Problem
Existing variable valve devices suffer from uneven wear of the high cam nose and sliding surface due to biased contact, leading to inclination of the sliding surface of the high speed rocker arm, which affects the performance and longevity of the valve mechanism.
Innovation Solution
A variable valve device design that includes a low speed rocker arm with a through hole parallel to the rocker shaft, a connecting pin, and a high speed rocker arm with an engagement portion, where the center of contact between the connecting pin and engagement portion matches or is closer to the camshaft center than the high speed cam contact, preventing inclination of the high speed rocker arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clearance is provided between the through hole and engaging member to allow sliding and tolerate working dimensions, then the engaging member can slide freely, but the sliding surface of the high speed rocker arm becomes inclined and biased contact occurs
Solution Approach 1:
The patent applies preliminary anti-action by positioning the contact point between the connecting pin and engagement portion at a specific location (matching or closer to camshaft center than high speed cam contact) to preemptively counteract the inclination tendency of the sliding surface. This preliminary positioning prevents the biased contact from occurring in the first place, rather than attempting to correct it after the fact.
Solution Approach 2:
The patent changes the positional parameter of the contact point between the connecting pin and engagement portion. By locating this contact point at a specific position (matching or closer to camshaft center than the high speed cam contact point), the geometric parameters of the mechanism are altered to eliminate the inclination of the sliding surface while maintaining the necessary clearance for sliding motion.
2Manufacturing precision
If the diameter of the through hole is made slightly larger than the diameter of the engaging member, then working tolerances are allowed, but the high cam nose and sliding surface experience unequal wear
Solution Approach 1:
The patent changes the positional parameter of the contact point to compensate for the clearance between the through hole and engaging member. By positioning the contact point between the connecting pin and engagement portion at a specific location, the adverse effects of the clearance on wear distribution are counteracted, allowing tolerance accommodation without sacrificing component longevity.
Solution Approach 2:
The specific positioning of the contact point serves as a preliminary countermeasure against the unequal wear that would result from the clearance. This design choice preemptively addresses the wear issue by ensuring that the high speed cam and sliding surface maintain proper alignment despite the necessary clearance for assembly tolerances.
3Adaptability or versatility
If the connecting pin is allowed to incline within the clearance range, then sliding is enabled, but the high speed rocker arm sliding surface becomes non-linearly contacted
Solution Approach 1:
The patent changes the positional parameter of the contact point between the connecting pin and engagement portion to a specific location (matching or closer to camshaft center). This parameter change ensures that even when the connecting pin inclines within the clearance range to enable sliding, the contact alignment between the high speed cam and sliding surface is maintained, preserving manufacturing 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 design reduces the likelihood of inclination of the high speed rocker arm, ensuring equal wear and improved performance by maintaining a line contact state between the high speed cam and sliding surface, thus enhancing the durability and efficiency of the valve mechanism.
Implementation Method 1
The cylinder hole is in communication with the hydraulic pump through an oil passage. The actuator includes a cylinder hole (hydraulic cylinder) formed at the cylinder head and a piston (hydraulic piston) slidably inserted into the cylinder hole.
Implementation Method 2
A clearance is always provided between the through hole and the engaging member in order to allow the engaging member to slide
Implementation Method 3
A coil-shaped rocker arm spring (lost-motion spring) is provided around a pivotal shaft of the rocker arm and the spring urges the second rocker arm so that the second rocker arm and the high cam nose are engaged with each other
Data Source
AI summary
A variable valve device is constructed to prevent inclination of a sliding surface of a high speed rocker arm. In an engagement surface where a connecting pin and the engagement portion of a high speed rocker arm are in contact, the center of the width of the surface in the direction of the cam shaft is provided closer to the high speed rocker arm than the center of the width in the direction of the camshaft of a cam contact surface where the high speed cam and the sliding surface of the high speed rocker arm are in contact. The low speed rocker arm includes a cam receiver and a connecting portion. The width of the connecting portion is larger than that of the cam receiver. The side surface of the connecting portion projects beyond the side surface of the cam receiver. The high speed rocker arm includes a cam receiver and a connecting portion. The side surface of the connecting portion and the side surface of the connecting portion are provided in the cam contact surface and within the width of the surface in the direction of the camshaft.