Camshaft Radial Displacement Prevention Using End Securing Device
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing camshafts with adjustable cam elements face issues of radial displacement between the inner and outer shafts during assembly and transport, affecting their coaxial arrangement and functionality.
Innovation Solution
A camshaft design featuring a securing device at the axial end of the inner shaft, which is directly supported against the step-free interior surface of the outer shaft, ensuring radial security and lubrication through an annular space filled with oil, preventing displacement and maintaining coaxial alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner shaft is mounted by pressing fastening pins through wall openings, then the cam elements can be connected between shafts, but radial displacement occurs during assembly and transport
Solution Approach 1:
The securing device is pre-installed on the inner shaft before assembly, creating a preliminary securing structure that prevents radial displacement during the subsequent pin insertion and transport processes. The securing device with securing element and bearing surface is prepared in advance to ensure precise coaxial alignment.
Solution Approach 2:
The securing device acts as an intermediary element between the inner shaft and outer shaft. The securing element on the inner shaft interacts with the bearing surface in the outer shaft to prevent radial displacement, serving as a mediator that ensures precise positioning without requiring direct pin-to-shaft contact.
2Strength
If the inner shaft is secured with multiple fastening pins, then the connection strength increases, but the friction and complexity increase
Solution Approach 1:
The securing function is extracted from the fastening pin system and implemented through a dedicated securing device with a securing element and bearing surface. This separates the positioning function from the connection function, allowing the pins to focus solely on transmitting forces while the securing device maintains coaxial alignment.
Solution Approach 2:
The securing device performs multiple functions: it secures the inner shaft radially, provides a bearing surface for the outer shaft, and maintains coaxial alignment during assembly and transport. This multi-functional approach replaces what would otherwise require multiple separate components.
3Manufacturing precision
If the inner shaft is rigidly fixed to prevent displacement, then alignment is maintained, but the adjustment capability of cam elements is reduced
Solution Approach 1:
The securing device provides rigid constraint only in the radial direction where coaxial alignment is needed, while leaving the axial and circumferential directions free for cam element adjustment. The bearing surface contacts the securing element locally to prevent radial displacement without affecting other degrees of freedom.
Solution Approach 2:
The securing device creates a dynamic balance between constraint and freedom: it constrains the inner shaft radially to maintain alignment during assembly and transport, but allows the cam elements to be adjusted circumferentially for variable valve timing control once assembled.
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 solution effectively prevents radial displacement between the inner and outer shafts during assembly and transport, ensuring reliable operation and reducing manufacturing and assembly costs by providing a combined securing and sealing element.
Implementation Method 1
The at least one securing device arranged at one axial end of the inner shaft secures the inner shaft radially in the outer shaft
Implementation Method 2
an annular space is provided between an outer lateral surface of the inner shaft and an interior lateral surface of the outer shaft, and this annular space is filled with oil, for example, for lubrication of the inner shaft with respect to the outer shaft
Data Source
AI summary
The present invention relates to a camshaft (1) which comprises an inner shaft (5) which is arranged coaxially in the outer shaft (6). Here, the outer shaft (6) is formed as a round cylindrical tube with a constant inner diameter (d) throughout, that is to say with a stepless inner lateral surface (9). Here, it is essential to the invention that the inner shaft (5) is secured directly against the stepless inner lateral surface (9) of the outer shaft (6) by means of at least one securing device (10) which is arranged axially at the end side of the inner shaft (5).