Resin Step Unit with Integrated Drive Device Recess
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional step units with drive devices fixed to the upper surface of the step member protrude upward, hindering low-floor designs and complicating waterproofing, and the configuration limits space for accommodating the drive device.
Innovation Solution
A step unit with a resin-molded step member featuring an accommodation portion below the upper surface, reducing upward protrusion of the drive device, and a peripheral wall to prevent water ingress, along with integrally molded non-annular shaft support and regulation portions for pulley attachment and belt guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive device is fixed to the upper surface of the step member, then the drive device is easily accessible and simple to install, but the drive device protrudes upward significantly, hampering low-floor design
Solution Approach 1:
The invention transitions the drive device from a horizontal mounting arrangement (on the upper surface) to a vertical mounting arrangement (in the lower surface accommodation portion). This dimensional change allows the drive device to be positioned below the step member's upper surface, eliminating upward protrusion while maintaining accessibility through the opening in the lower surface.
Solution Approach 2:
The drive device is nested within the accommodation portion formed in the lower surface of the step member. The housing of the drive device fits into this recessed space, with the peripheral wall enclosing it, creating a nested structure that hides the drive device from the upper surface view while maintaining functional accessibility.
2Shape
If the drive device is fixed to the lower surface of the step member, then upward protrusion is reduced, but the space below the step member is limited and waterproof design becomes complicated
Solution Approach 1:
The invention merges the waterproofing function into the structural design by forming an integrated peripheral wall that encloses the accommodation portion. This peripheral wall creates a natural waterproof barrier that prevents water from reaching the drive device, eliminating the need for separate waterproofing components or complex sealing systems.
Solution Approach 2:
The peripheral wall acts as a protective shell that encloses the drive device in the accommodation portion. This shell structure provides inherent waterproof protection by forming a continuous barrier between the drive device and the external environment, particularly preventing water ingress from above the step member.
3Ease of manufacture
If sheet-metal processing is used for the step member, then manufacturing is conventional and simple, but the step member cannot accommodate complex shapes like deep recesses for the drive device
Solution Approach 1:
The invention changes the material parameter from sheet metal to resin, which fundamentally enables new geometric possibilities. Resin molding allows the creation of complex three-dimensional shapes including deep accommodation portions, integrated peripheral walls, and varied surface geometries that cannot be achieved through conventional sheet-metal processing.
Solution Approach 2:
The step member is formed as a resin-based composite structure that integrates multiple functional elements (accommodation portion, peripheral wall, fastening features, belt guidance) into a single molded component. This resin composite approach combines structural support with complex geometric features that would require multiple separate metal components and assembly steps.
4Reliability
If additional components like brackets are used for pulley attachment, then the pulley can be securely attached, but the device complexity increases and assembly becomes more difficult
Solution Approach 1:
The invention merges the pulley attachment function directly into the step member structure through integrally formed shaft support portions and belt guidance features. These molded-in structures eliminate the need for separate brackets or attachment components, reducing part count while maintaining secure pulley attachment and proper belt alignment.
Data Source
Figure 1
Figure 2
Figure 3~4B
AI summary
A step unit (1) comprises: a step member (3) which is provided on the vehicle body side so as to be adjacent to a slide door of the vehicle and has a flat plate section (4) on which an occupant's foot is placed; and a drive device (2) which is affixed to the step member (3) and drives the slide door to open and close the slide door. The step member (3) is molded using a resin material and has a accommodation portion (5) which is provided with a bottom (5a) formed below the upper surface (4a) of the flat plate section (4). The drive device (2) is affixed while at least a part thereof is accommodated within the accommodation portion (5).