Elastic Crawler Engaging Portions Asymmetric Envelope Geometry
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Solution Overview
Problem
The existing elastic crawler design experiences significant interference between pin members and engaging portions due to their isosceles triangular shape, leading to reduced durability.
Innovation Solution
The elastic crawler features pressure receiving surfaces and flanks with specific outline shapes defined by envelopes drawn by pin members, with rolling diameters calculated using formulas D1=D0×a and D2=D0×b, where 0.9≤a<1 and 1≤b≤1.1, respectively, to minimize interference and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engaging portions have an isosceles triangular shape with inclined surfaces, then the pin members can be engaged with the engaging portions, but the interference between the pin members and the engaging portions is large, reducing durability
Solution Approach 1:
The patent changes the symmetric isosceles triangular shape to an asymmetric shape where the pressure receiving surface has a specific outline formed by an envelope drawn by the outer end of pin members. This asymmetric design allows the pressure receiving surface to better accommodate the pin member geometry, reducing interference while maintaining engagement functionality.
Solution Approach 2:
The patent defines specific geometric parameters for the pressure receiving surface using the envelope formula where the outline is determined by the rolling diameter D1=D0×a (0.9≤a<1). By optimizing these parameters, the design achieves reduced interference between pin members and engaging portions while maintaining effective engagement.
2Object-affected harmful factors
If the pressure receiving surface uses a smaller rolling diameter (D1=D0×a, 0.9≤a<1), then the interference between pin members and engaging portions is suppressed, but the engagement geometry becomes more complex
Solution Approach 1:
The pressure receiving surface geometry is defined by the envelope drawn by the outer end of the pin members themselves during the rolling motion. The pin members effectively generate their own optimal engagement surface geometry through their motion trajectory, eliminating the need for separate complex tooling or multi-step manufacturing processes.
Solution Approach 2:
The envelope formation process inherently creates a curved, adaptive surface that follows the rolling motion trajectory. This curvature allows the pressure receiving surface to smoothly accommodate the pin members during engagement, reducing interference while maintaining a manufacturable geometry through a single forming operation.
3Reliability
If the flank is designed with a larger rolling diameter (D2=D0×b, 1≤b≤1.1), then the durability is improved and volume is increased, but the interference may increase during breaking or downhill operations
Solution Approach 1:
The patent applies different rolling diameter parameters to different regions of the engaging portions: the pressure receiving surface uses D1=D0×a (0.9≤a<1) for reduced interference during normal engagement, while the flank uses D2=D0×b (1≤b≤1.1) for increased durability and volume. This localized differentiation optimizes each region for its specific function.
Solution Approach 2:
The flank design with larger rolling diameter provides additional clearance and volume that accommodates dynamic conditions during breaking or downhill operations where reverse forces may occur. The increased volume and adjusted geometry allow the engaging portions to better handle variable loading conditions without excessive interference.
Data Source
AI summary
An elastic crawler and an elastic crawler drive mechanism collectively suppress the interference between the pin members and the engaging portions, and improve the durability of the engaging portions. The elastic crawler includes on an inner circumferential side thereof a plurality of engaging portions (14) respectively engageable with a plurality of pin members (22) arranged at a spacing in a circumferential direction of a sprocket, wherein: the engaging portions (14) have a pressure receiving surface (14a) which receives the pin members (22), an outline shape in side view of the pressure receiving surface (14a) being formed by an envelope L1 drawn by an outer end of the pin members (22) when the sprocket rolls coaxially with a central axis of a virtual rotor with a rolling diameter D1 defined by D1=(pitch of the engaging portions)×(number of pin members)/(π)×a, and 0.9≤a≤1, together with the virtual rotor on a plane.