Variable Valve Gear Connecting Pin Guide Surface Alignment
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Solution Overview
Problem
Conventional variable valve apparatuses face issues with low certainty of connection between rocker arms for low speed and high speed, leading to inconsistent operating states due to potential collisions and misalignment, which affects the accurate engagement of cam profiles and valve lift profiles.
Innovation Solution
The apparatus includes a guide surface with an arc shorter than a semicircle on the rocker arm for high speed, a cylindrical engaging hole, and strategically positioned through-holes to improve alignment and connection rigidity, ensuring the connecting pin can advance even when not precisely aligned, and reducing deflection and interference with spring seats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a taper-like chamfer is formed on the opening edge of the pinhole to facilitate advancement of the switching pin, then the switching pin can advance to the pinhole easily, but the rocker arm for high speed can be pushed by the cam for high speed to flip the forward end of the switching pin at the time when the forward end of the switching pin contacts the tapered surface, resulting in low certainty of connection between rocker arms
Solution Approach 1:
The invention replaces the taper-like chamfer with a curved guide surface having a radius of curvature of 5 to 15 mm. This curved surface guides the forward end of the switching pin smoothly into the engaging hole of the rocker arm for high speed, preventing the pin from flipping while maintaining ease of advancement. The curvature provides a controlled path that eliminates the harmful flipping effect caused by the tapered surface.
2Adaptability or versatility
If the forward end of the switching pin is advanced by the hydraulic piston, then the rocker arm for high speed and the rocker arm for low speed are interlocked, but the connection certainty is low due to potential flipping and misalignment
Solution Approach 1:
The invention introduces a guide surface as an intermediary element between the switching pin and the engaging hole. This guide surface mediates the connection process by guiding the pin into proper alignment with the engaging hole, ensuring reliable interlocking between the rocker arms for high speed and low speed without flipping or misalignment issues.
Solution Approach 2:
The guide surface performs preliminary alignment action before the switching pin fully engages with the engaging hole. By pre-positioning the pin correctly as it approaches the hole, the system ensures proper alignment and prevents flipping, thereby improving the certainty of connection before the final interlocking occurs.
3Device complexity
If conventional pinhole design is used, then the structure is simple, but the switching pin may collide with the opening edge and fail to perform connecting operation normally
Solution Approach 1:
The invention modifies the pinhole opening edge by providing a guide surface with a curved profile instead of a sharp edge or simple chamfer. This curved surface has a radius of curvature of 5 to 15 mm, which allows the switching pin to advance smoothly without collision while maintaining relatively simple overall structure. The curvature eliminates the collision problem while adding minimal structural 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 design enhances the certainty of connection between rocker arms, improves manufacturing accuracy, and allows for increased design freedom by ensuring a desired operating state with reduced deflection and improved rigidity, aligning cam and valve profiles effectively.
Implementation Method 1
the switching pin withdrawn by the spring force of a coil spring
Implementation Method 2
the switching pin advanced by the hydraulic piston
Data Source
Figure 1
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AI summary
In a variable valve apparatus, a second connector has a fifth side surface located below a fourth side surface and further away from a second side surface than is the fourth side surface, so that a width in a direction along a rocker shaft is narrower in a lower portion adjacent to an inlet valve than in an upper portion adjacent a slipper surface. A guide surface is provided in a lower portion of the fourth side surface and includes an arc that is shorter than a semicircle, and coaxial and equal in radius with an engaging hole. Thus, even when a connecting pin is advanced in a state of a through-hole and the engaging hole not being in precise alignment, the forward end of the connecting pin is guided through the guide surface into the engaging hole. An extended period can therefore be secured for advancing the connecting pin, to improve the certainty of connection.