Plate Spring Unit for Railcar Bogie Reducing Thickness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing railcar bogie designs face issues with weight and cost due to heavy steel frames, and while omitting side sills reduces weight, they struggle to maintain functionality and space efficiency when plate springs are damaged, making it difficult to achieve a low floor carbody.
Innovation Solution
A plate spring unit with multiple plate springs arranged perpendicular to the thickness direction, including a softer interposed member between them, which allows for elastic deformation and division along the longitudinal direction to ensure functionality even if one spring is damaged, reducing occupied space and maintaining support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple plate springs are stacked in the upper-lower direction to ensure adequate supporting function when damaged, then the reliability is improved, but the occupied space in the thickness direction becomes large
Solution Approach 1:
The patent transitions from stacking plate springs in the thickness direction (vertical dimension) to arranging them side by side in the width direction (horizontal dimension). This dimensional change allows multiple springs to be configured for redundancy without increasing the vertical space occupation, thus resolving the contradiction between reliability and volume.
Solution Approach 2:
The patent divides the suspension system into multiple independent plate springs arranged laterally rather than stacked vertically. Each plate spring functions as an independent load-bearing element, and their lateral arrangement provides both functional redundancy and space efficiency, addressing the contradiction between reliability and occupied space.
2Weight of stationary object
If side sills are omitted from the bogie frame to reduce weight, then the weight is reduced, but the structural complexity increases
Solution Approach 1:
The plate springs serve multiple functions: they act as both the suspension element and the structural member that would traditionally be performed by side sills. By making the plate springs multi-functional, the patent eliminates the need for separate side sills, reducing weight while managing structural complexity through functional integration.
Solution Approach 2:
The patent extracts and removes the side sills from the bogie frame structure, relying instead on the plate springs to provide both suspension and structural support. This extraction simplifies the overall structure by eliminating redundant components, thereby reducing weight while the plate spring configuration manages the necessary structural complexity.
3Device complexity
If a single plate spring is used to support the cross beam to reduce device complexity, then the device complexity is reduced, but the reliability decreases when damaged
Solution Approach 1:
The patent segments the suspension system into multiple independent plate springs arranged laterally instead of using a single spring or vertically stacked springs. This segmentation provides functional redundancy - if one spring is damaged, others continue to support the load - while keeping the overall device complexity manageable through a simple lateral arrangement.
Solution Approach 2:
The patent uses multiple plate springs providing more supporting capacity than a single spring would offer. This excessive action ensures that even if one or more springs are damaged, adequate supporting function remains, thus improving reliability while the simple lateral arrangement keeps device complexity low.
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
This configuration reduces the occupied space in the thickness direction, ensures the plate spring unit's functionality even if damaged, and allows for the realization of a low floor carbody by preventing excessive space usage.
Implementation Method 1
each of the plurality of plate springs elastically deform in a thickness direction that is an upper-lower direction
Implementation Method 2
the interposed member is lower in hardness than the first and the second plate springs
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A railcar bogie (1) includes: a cross beam (4) configured to support a carbody (11) of a railcar; a pair of front and rear axles (5) between which the cross beam is located and which are respectively arranged in front of and behind the cross beam (4) in a railcar longitudinal direction so as to extend in a railcar width direction; bearings (7) respectively provided at both railcar width direction sides of each of the axles (5) and configured to rotatably support the axles (5); axle boxes (8) configured to respectively accommodate the bearings (7); and a plate spring unit (30) configured to extend in the railcar longitudinal direction so as to support one of both railcar width direction end portions (4a) of the cross beam (4) and including both longitudinal direction end portions (30c) respectively supported by the axle boxes (8). The plate spring unit (30) includes a plurality of plate springs (41 and 42) configured to elastically deform in a thickness direction that is an upper-lower direction. The plurality of plate springs (41 and 42) are arranged so as to be lined up in a width direction perpendicular to the longitudinal direction and the thickness direction.