Variable Valve-Operating Device Axial Width Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable valve-operating devices for internal combustion engines are bulky due to the large axial width required for lead grooves, which hinders miniaturization.
Innovation Solution
A cam carrier design with adjacent speed increasing and decreasing side lead grooves that overlap in the axial direction, allowing for a reduced axial width by using switching pins that engage and disengage from specific portions of the grooves, enabling smooth shifting and rotation without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lead grooves are formed in the cam carrier to enable axial shifting, then the cam carrier can be moved between low speed and high speed positions, but the axial width of the cam carrier increases
Solution Approach 1:
The patent applies dimensional change by forming lead grooves that extend in the circumferential direction rather than purely in the axial direction. The grooves wrap around the cam carrier circumference, allowing axial positioning to be achieved through circumferential groove design. This transforms the problem from requiring axial space to using circumferential space, thereby reducing the axial width while maintaining the switching functionality between low speed and high speed cam lobes.
Solution Approach 2:
The patent implements nesting by placing the low speed side lead groove and high speed side lead groove in an overlapping axial arrangement. The grooves are nested within each other's axial space, with each groove containing entry, switching, and steady position portions that are axially stacked. This nested configuration allows both grooves to share the same axial region, significantly reducing the total axial width required compared to having separate, non-overlapping grooves.
2Ease of operation
If separate lead grooves are formed for speed increasing and speed decreasing operations, then directional control is achieved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing each lead groove to serve multiple purposes within its structure. Each groove contains an entry lead groove portion for initial engagement, a switching lead groove portion for directional transition, and a steady position lead groove portion for maintaining position. This multi-functional design within each groove reduces the need for separate specialized grooves, simplifying the overall structure while maintaining precise directional control for both speed increasing and speed decreasing operations.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A variable valve-operating device for an internal combustion engine has a cam carrier (3) with cam lobes (3L, 3H) formed therearound to act on an engine valve and with a speed increasing side lead groove (4) and a speed decreasing side lead groove (5) formed therearound to be engaged with a speed increasing side switching pin (8p) and a speed decreasing side switching pin (9p), respectively, to axially shift the cam carrier (3), to selectively make one of the cam lobes (3L, 3H) to be operative. A speed increasing side entry lead groove portion (4a) of the speed increasing side lead groove (4) is formed in a position axially overlapping a low speed steady position lead groove portion (5c) of the speed decreasing side lead groove (5). A speed decreasing side entry lead groove portion (5a) of the speed decreasing side entry lead groove (5) is formed in a position axially overlapping a high speed steady position lead groove portion (4c) of the speed increasing side lead groove (4). The variable valve-operating device can thus be miniaturized by reducing the axial width of the cam carrier.