Crankshaft Recess and Bore Layout for Lightweight Forging
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Solution Overview
Problem
Current methods for manufacturing crankshafts are not effective in achieving a lightweight design with optimal flexural and torsional strength while minimizing the need for finishing and balancing, and are not cost-efficient or simple to execute.
Innovation Solution
A crankshaft design featuring recesses with planar bottom surfaces in the crank discs and crankpins, allowing for easier drilling of bores and reduced weight, combined with a forging method using specialized tools to form these recesses, which facilitates the manufacturing process and maintains strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If recesses and bores are added to crankpins to reduce weight, then the weight of the crankshaft is reduced, but the manufacturing complexity and difficulty increase
Solution Approach 1:
The recesses with planar bottom surfaces are formed in the crank discs during the forging process before the actual boring operation. This preliminary action prepares the workpiece by creating ready-to-drill surfaces, making the subsequent boring operation simpler and more precise while maintaining the weight reduction benefit
2Weight of moving object
If complex forging and stamping processes are used to create recesses and bores, then weight reduction is achieved, but manufacturing time and cost increase
Solution Approach 1:
The formation of recesses and the boring operation are merged into a single integrated manufacturing step. The forging tool simultaneously creates the recess with the planar bottom surface and positions the bore, eliminating separate stamping and boring operations. This combines multiple processes into one, reducing manufacturing time and cost while achieving the same weight reduction
3Ease of manufacture
If traditional forging methods are used without planar bottom surfaces, then manufacturing is simpler, but drilling precision and accuracy decrease
Solution Approach 1:
Instead of making the entire crank disc surface planar, only the specific area where the bore needs to be drilled is made planar through the recess. This localized planar surface provides the necessary precision for accurate bore drilling while keeping the rest of the crank disc structure simple and easy to manufacture
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
The design and manufacturing method result in a lightweight crankshaft with improved strength and reduced need for balancing and finishing, leading to weight reduction in vehicles and lower fuel consumption.
Implementation Method 1
a forging tool is formed with a protrusion that, upon forging, forms a recess with a planar bottom surface
Data Source
AI summary
A crankshaft (4) with a first central axis (A), has at least two main bearing journals (12), through which the first central axis (A) extends. At least one crankshaft web (10) is arranged between the main bearing journals (12), wherein the at least one crankshaft web (10) comprises two crank discs (14) connected with each other via a crankpin (16) with a second central axis (B). At least one crank disc (14) has a recess (26) with a planar bottom surface (28), wherein the recess (26) is adapted in the at least one crank disc (14) in such a way that the second central axis (B) of the crankpin (16) cuts the planar bottom surface (28). That planar bottom surface (28) is oriented at a right angle in relation to the direction of the second central axis (B) of the crankpin (16). A bore (30) with a third central axis (C) extend through the planar bottom surface (28) of the recess (26), through the at least one crank disc (14), and into the at least one crankpin (16). Also, a combustion engine (2), a vehicle (1) and a method for manufacture of a crankshaft (4) are disclosed.