Camshaft Torque Transmission via Partial Surface Roughening
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Solution Overview
Problem
The existing camshaft joining processes are limited by friction between the cam and shaft surfaces, leading to restricted torque transmission and increased manufacturing costs due to the need for extensive surface roughening.
Innovation Solution
Partial roughening of the cam and shaft joining surfaces, specifically in load-critical areas, using methods like laser ablation, blasting, or chemical treatment to enhance torque transmission while reducing manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire joining surface is roughened to increase torque transmission, then the torque capacity is improved, but the manufacturing time and costs increase
Solution Approach 1:
The patent applies roughening treatment only to specific load-critical areas (cam elevation area and opposite base circle) rather than the entire joining surface. This localized approach concentrates the roughness where highest pressures and torques occur, maintaining torque transmission capacity while significantly reducing the area requiring treatment and thus manufacturing time
Solution Approach 2:
The patent uses partial roughening action instead of complete surface roughening. By treating only the necessary portions (areas with circumferential angles of approx. 20-140° in load-critical zones) with roughness values of 2-25 Rz, the process achieves sufficient torque transmission without the excessive time and cost of treating the entire surface
2Reliability
If the entire joining surface is roughened to ensure reliable connection, then the connection reliability is improved, but the manufacturing complexity and costs increase
Solution Approach 1:
The patent identifies and treats only the load-critical areas (cam elevation and opposite base circle) with roughening, leaving other areas untouched. This selective approach maintains connection reliability in the most stressed zones while simplifying the overall manufacturing process by reducing the treated area and associated complexity
3Productivity
If partial roughening is applied only in load-critical areas, then the manufacturing time is reduced, but the torque transmission capacity may be compromised
Solution Approach 1:
The patent strategically places roughness in the load-critical areas (cam elevation area and opposite base circle) where the highest pressures and torques are transmitted. By concentrating roughness in these specific zones with circumferential angles of approx. 20-140°, the treatment maintains torque transmission capacity while minimizing the treated area to accelerate production
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 approach allows for efficient torque transmission with reduced cycle times and lower manufacturing costs by focusing roughening on high-stress areas, resulting in improved camshaft assembly efficiency and increased torque capacity.
Implementation Method 1
the inner surfaces of the cam openings and/or the outer surface of the idler shaft having a rough pattern produced by laser ablation in the sections surrounded by the cam openings in the inserted state exhibit
Implementation Method 2
Thermal joining processes are generally used to join the shaft and the cams
Implementation Method 3
Bringing about a temperature equalization between the idler shaft and the cams, so that the idler shaft and the cams are firmly connected
Implementation Method 4
Supercooling an idler shaft with a round outer profile relative to the cams, the outer diameter of the supercooled idler shaft being smaller
Data Source
Figure 1~3
Figure 4~6
Figure 7~10
AI summary
The invention relates to a camshaft (1) for an internal combustion engine, comprising a shaft (2) and at least one component (3) that is joined to said shaft, in a thermal manner in particular. The component is connected to a joint surface (6) of the shaft via a joint surface (5) of the component. It is essential to the invention that the joint surface (5) of the component and/or the joint surface (6) of the shaft has/have a defined roughness (7) only partially on regions that are load-critical. The invention further relates to a cam (4) for such a camshaft (1) and to a method for producing such a camshaft (1) or such a cam (4).