Camshaft Axial Thrust Compensation via Cam Follower Sorting
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Solution Overview
Problem
Tolerances in the production of mounts for cam followers in internal combustion engine valve trains lead to axial displacement of the camshaft, resulting in increased friction, wear, and noise due to axial thrust, which is costly to avoid without compromising production quality.
Innovation Solution
Cam followers are pre-sorted into two main groups with offset mounts to compensate for axial thrust, with each group further divided into sub-groups for precise alignment, minimizing axial displacement and friction in the camshaft's axial bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard production tolerances are used for mounts in cam followers, then manufacturing costs are reduced and production efficiency is improved, but axial thrust causes camshaft displacement leading to increased friction, wear, and noise
Solution Approach 1:
Cam followers are pre-sorted into two groups based on the direction of their mount offsets (clockwise or counterclockwise deviation from perpendicular). This preliminary classification allows for strategic assembly where the directional offsets are deliberately arranged to counterbalance axial thrust forces on the camshaft, preventing bearing contact and reducing friction and wear while maintaining standard production tolerances
Solution Approach 2:
The mount offsets in cam followers are designed to create counterbalancing forces. By sorting cam followers into groups with opposite offset directions and strategically positioning them, the transverse forces generated by one group counteract the axial thrust from the other group, effectively neutralizing the harmful axial load on the camshaft bearing
2Object-affected harmful factors
If mount offsets are minimized to eliminate axial thrust, then friction and wear are reduced, but manufacturing precision requirements and costs increase significantly
Solution Approach 1:
Instead of requiring symmetric, perfectly perpendicular mount alignment, the invention deliberately introduces asymmetric offsets in controlled directions (clockwise or counterclockwise). These asymmetric mounts are sorted into groups and assembled to create overall balance, reducing the need for high-precision manufacturing while achieving the goal of minimizing axial thrust through strategic imbalance compensation
3Object-affected harmful factors
If cam followers are pre-sorted into groups with opposite offset directions, then axial thrust is compensated and bearing wear is reduced, but assembly complexity increases
Solution Approach 1:
The sorting of cam followers into two groups based on offset direction is performed during or after manufacturing, before final assembly. This preliminary action simplifies the final assembly process, as workers only need to place pre-sorted components into corresponding positions rather than performing complex measurements and calculations during assembly
Solution Approach 2:
The sorting process acts as an intermediary step between manufacturing and final assembly. By introducing this intermediate classification stage, the system transforms a potentially complex assembly task into a simpler process where pre-categorized components are systematically positioned to achieve force balance
Data Source
AI summary
A method for mounting a valve train (1) of an internal combustion engine, having, parallel to a row of cam followers (2), a camshaft (13) which has a cam (15) per cam follower (2), which cam (15) acts on the roller (10) of said cam follower (2), which camshaft (13) is supported with respect to the cylinder head (3) via an axial bearing (14), wherein a) the cam followers (2) are provided presorted into two main groups (A, B); b) the two mounts (11) of each cam follower (2) of the first main group (A) run with offset in relation to the longitudinal extent of the cam follower (2) in the side surfaces (12) with respect to one another in such a way that an axial line of the pin (9) differs in the clockwise direction from perpendicular; c) the offset of the second main group (B) differs in the counterclockwise direction from perpendicular, and d) a partial quantity of the first and second main group (A, B) are selected and mounted for each row of cam followers (2) in order to minimize/compensate for an axial thrust of the camshaft (13).