Inner Lever Punch-Bending for Valve Train Manufacturing
Solution Overview
Problem
The existing inner lever of a switchable finger lever in a valve train of an internal combustion engine has a complex and solid construction, making it expensive and difficult to produce in mass quantities due to the need for boring and reaming of openings for the shaft and roller pin.
Innovation Solution
The inner lever is fabricated using punch-bending techniques from steel sheet metal with thin-walled lateral walls and transverse bars, featuring crimped arms that taper into longitudinal bars, eliminating the need for boring and allowing for economic production through punch-bending processes, and optionally connected by welding or other methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner lever is constructed with solid material and traditional machining methods, then the structural strength and reliability are improved, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent applies thin-walled sheet metal construction for the inner lever, replacing traditional solid material. The lateral walls, transverse bar, and longitudinal bars are all formed as thin-walled structures through punch-bending processes, eliminating the need for complex machining while maintaining sufficient structural strength for the valve train application.
Solution Approach 2:
The patent changes the manufacturing parameters from traditional machining (boring, reaming) to punch-bending processes. This parameter change allows the inner lever to be formed directly from sheet metal with the required geometries, including the crimped arms and longitudinal bars, without needing complex machining operations.
2Manufacturing precision
If traditional machining methods (boring, reaming) are used to create openings for shaft and roller pin, then the manufacturing precision is improved, but the production time and cost increase
Solution Approach 1:
The openings for the shaft and roller pin are created during the punch-bending process itself, rather than as a subsequent machining step. The punch-bending operation simultaneously forms the longitudinal bars and creates the openings, eliminating the need for separate boring and reaming operations.
Solution Approach 2:
The patent merges multiple manufacturing operations into a single punch-bending process. The formation of longitudinal bars, creation of openings for shaft and roller pin, and shaping of crimped arms are all accomplished in one integrated operation, significantly improving production efficiency.
3Ease of manufacture
If the inner lever is made with thin-walled structures through punch-bending, then the manufacturing cost and complexity are reduced, but the structural rigidity may be compromised
Solution Approach 1:
The inner lever is segmented into multiple thin-walled components (lateral walls, transverse bar, longitudinal bars) that are formed separately through punch-bending and then assembled together. This segmentation allows each component to be optimized for manufacturability while the assembly provides the necessary overall structural rigidity.
Solution Approach 2:
The inner lever uses composite construction with thin-walled sheet metal structures assembled together. The lateral walls, transverse bar, and longitudinal bars are formed from sheet metal and connected through welding or other joining methods, creating a composite structure that achieves both manufacturing ease and sufficient structural strength.
Data Source
AI summary
An inner lever (1) for a switchable finger lever (2) of a valve train of an internal combustion engine is provided, having a box-like main part (5) with two lateral walls (6), which are connected at a first end (7) by a transverse bar (8), which intrinsically includes a driver surface (9) for a coupling slide that can be guided longitudinally by the outer lever (3), and opposite from the first end (7), the lateral walls (6) have two strongly crimped together, thin-walled arms (10), which each extend in the direction toward the second end (11) of the inner lever (1) to form a longitudinal bar (12). The arms contact each other with their inner sides (15), and between the lateral walls (6), a cam contact surface (16) can be provided. The inner lever (1) made from thin-walled steel sheet metal at least to a large extent using punch-bending techniques.