Steel Piston Cooling Duct Shoulder Connection
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Solution Overview
Problem
Existing piston designs for internal combustion engines with cooling channels face issues such as foreign body contamination, increased manufacturing complexity and cost due to screw connections, and reduced rigidity due to unsuitable attachment methods, leading to potential tilting and reduced usability.
Innovation Solution
The design features an upper and lower web with a larger diameter protruding radially around the circumference, with a shoulder-shaped contact area to guide and support the ring element, allowing for a form-fitting and material-fitting connection that enhances strength and simplifies assembly, while reducing wall thickness and manufacturing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw connection is used to attach the ring element to the piston base body, then the connection strength is improved, but the manufacturing complexity and cost increase due to threading operations
Solution Approach 1:
The attachment structure is segmented into distinct functional elements: the ring element with its attachment portion, the piston base body with receiving structure, and the integrated shoulder feature. This segmentation allows each part to be optimized independently while simplifying the overall attachment mechanism by eliminating the need for threading operations.
Solution Approach 2:
Instead of creating threads in the piston base body to receive the ring element, the invention inverts the approach by providing a shoulder structure on the piston base body that the ring element attaches to. This reverses the conventional threading approach and eliminates the need for complex threading operations on the forged piston body.
2Strength
If a screw connection is used to attach the ring element to the piston base body, then the connection strength is improved, but the manufacturing time increases due to subsequent threading operations
Solution Approach 1:
The shoulder structure for attachment is built into the piston base body during the initial forging process, before any subsequent assembly operations. This preliminary action eliminates the need for time-consuming threading operations after the piston body is manufactured, significantly reducing total manufacturing time.
3Strength
If the ring element is screwed onto the piston body, then the connection is secure, but tilting can occur quickly leading to reduced usability
Solution Approach 1:
The shoulder structure provides self-aligning and self-supporting functionality during assembly and operation. The ring element naturally seats against the shoulder, which provides both vertical support and angular alignment, eliminating the need for additional alignment features or adjustment mechanisms that would be required with screw connections.
4Shape
If a lost core method is used to produce cooling channels, then the cooling channel shape can be achieved, but foreign bodies must be completely removed to prevent contamination
Solution Approach 1:
The lost core material is completely extracted from the piston body after the cooling channels are formed. This extraction process removes all foreign body contaminants that would otherwise remain in the engine oil circuit, while still allowing the cooling channel shape to be precisely defined by the core geometry during the casting process.
5Reliability
If a circumferential depression is introduced from below to close the accessible area, then the area can be sealed, but the piston becomes quite tall
Solution Approach 1:
Instead of creating the sealing structure by moving vertically (adding height through circumferential depression from below), the invention uses the radial dimension by providing a shoulder structure that extends radially outward from the piston base body. This dimensional shift allows sealing without increasing piston height.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a piston (1) which comprises a piston upper part (2) and a piston lower part (3), wherein there are an annular field which is formed by an annular element (9) and has annular grooves (4), a cooling duct (5) which runs behind the latter coaxially and radially and, in particular, a combustion-chamber recess (6) in the region of the piston upper part (2), and the piston lower part (3) has at least one piston skirt (7) and a corresponding pin hole (8), wherein there is provision according to the invention for the contact regions of the annular element (9) on the piston basic body to be designed with at least one shoulder shape and for the annular element (9) to be joined to the piston basic body non-releasably.