Telescopic Mast With Distinct Force Intersection Points
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Solution Overview
Problem
Conventional telescopic masts for tower cranes face challenges in efficiently transmitting torsional moments while maintaining low friction coefficients, leading to increased wear and power consumption, due to the concurrence of primary and secondary resultant forces at a single point, which complicates the design and manufacturing process.
Innovation Solution
The telescopic mast design features a first and second mast section with polygonal cross-sections, where primary and secondary support members transmit forces such that their intersection points are distinct, allowing intrinsic torque absorption by normal forces, reducing tangential components and enabling more efficient force transmission and reduced dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the directions of primary and secondary resultant forces concur at the same single point of intersection, then the structure is simpler, but the torsional moment is mainly taken up by friction which increases wear and power consumption
Solution Approach 1:
The patent divides the force transmission system into two separate functional groups: primary support members with their own point of intersection, and secondary support members with a different point of intersection. This segmentation allows each group to handle specific force components independently, with the primary supports handling normal forces and the secondary supports handling tangential forces, thereby reducing friction-based energy loss while maintaining structural integrity.
Solution Approach 2:
The patent transitions from a single-point force intersection to a two-point intersection system in the cross-sectional plane. By distributing the force intersections to two distinct points rather than one, the system creates a moment arm that enables intrinsic torque absorption through normal forces, effectively adding a dimensional aspect to force transmission that reduces reliance on friction.
2Reliability
If conventional solutions increase the number of contact zones and reduce play between sections, then torque transmission improves, but the design and manufacture becomes complex
Solution Approach 1:
The patent makes the support members multi-functional by designing them to simultaneously provide guidance during telescoping and force transmission during operation. The primary and secondary support members each serve dual purposes: guiding the relative movement of mast sections and transmitting specific force components, thereby eliminating the need for separate torque transmission mechanisms and reducing overall design complexity.
Solution Approach 2:
The patent changes the geometric parameters of the mast sections by using non-circular cross-sections (such as rectangular or polygonal shapes) with specifically oriented support members. This parameter change allows the normal forces at the support members to inherently resist torque, transforming the force transmission mechanism without adding complexity to the design or manufacturing process.
3Loss of energy
If the polygonal shape configuration creates distant primary and secondary intersection points, then torque is intrinsically taken up by normal forces reducing tangential components, but the cross-section design becomes more complex
Solution Approach 1:
The patent employs asymmetric cross-sectional shapes (such as rectangular or polygonal sections) rather than symmetric circular sections. This asymmetry is strategically designed so that the primary and secondary support members are positioned at specific locations that create distant points of intersection, enabling the normal forces to effectively resist torque while minimizing tangential force components.
Solution Approach 2:
The patent applies local quality by concentrating the force transmission function at specific localized regions (the primary and secondary support members) rather than distributing it uniformly. The polygonal cross-section is designed with specific faces and edges that provide optimal contact points for these support members, creating localized zones of high force transmission efficiency while maintaining overall structural integrity.
Data Source
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AI summary
This telescopic mast comprises a first mast section (10) and a second mast section (20) that slide. The first and second mast sections have polygonal cross-sections with at least eight faces. The first and second mast sections comprise at least two primary support members and at least two secondary support members located respectively in two regions separated by a neutral fiber plane (P31). The primary and secondary support members transmit torsional forces. The polygonal shapes of the cross-sections of the first and second mast sections are configured such that: the two primary support members transmit two primary forces (F11) resulting from bending and converging at a primary intersection point (P11), and the two secondary support members transmit two secondary forces (F21) resulting from bending and converging at a secondary intersection point (P21) distant from the primary intersection point (P11).