Belt Tension Roller Mounting to Prevent Torque-Induced Shift
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Solution Overview
Problem
Existing drive transmission mechanisms, such as those described in Japanese Patent Laid-Open No. 2013-40667, face limitations in adjusting belt tension due to the restricted range of screw hole sizes, which can lead to inadequate tension adjustment and potential movement of retaining members during screw fastening.
Innovation Solution
A drive transmission device with a chassis, a driving roller, a belt member, a support member that is rotatably and swingably mounted, and a retaining member that is engaged with the chassis, allowing the support member to be fixed between the retaining member and the chassis, enabling the adjustment of belt tension through a screw mechanism without being affected by torque-induced movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the screw inserting hole is formed larger than the screw diameter to facilitate assembly, then the ease of manufacture is improved, but the retaining member moves during screw fastening due to applied torque
Solution Approach 1:
The patent introduces a recess portion as an intermediary structure between the screw and the retaining member. This recess receives the screw head and provides a counterbore that prevents the screw from applying torque directly to the retaining member, thereby eliminating the movement issue while maintaining ease of assembly
Solution Approach 2:
The patent adds a dimensional feature (the recess portion extending in the screw insertion direction) to the retaining member. This creates a stepped structure where the screw head sits in a counterbore, separating the torque application zone from the retaining member body, thus preventing rotation while maintaining assembly ease
2Stability of the object's composition
If the screw inserting hole is formed smaller than the screw head in the tension adjustment direction to prevent movement, then the position stability is improved, but the range of tension adjustment is limited
Solution Approach 1:
The patent segments the screw inserting hole into two distinct portions: a first portion (counterbore) that is smaller than the screw head to prevent torque-induced movement, and a second portion that extends in the screw insertion direction to provide adequate clearance for tension adjustment. This segmentation allows both requirements to be satisfied simultaneously
Solution Approach 2:
The patent applies different dimensional characteristics to different portions of the screw inserting hole. The first portion (counterbore) has a smaller diameter to prevent rotation, while the second portion has sufficient length to enable tension adjustment, creating local quality variations that satisfy both stability and adjustability requirements
3Stability of the object's composition
If the screw inserting hole is formed in a cross shape to suppress torque-induced movement, then the position stability is improved, but the manufacturing complexity increases
Solution Approach 1:
Instead of making the screw inserting hole complex (cross-shaped) to prevent movement, the patent inverts the approach by creating a simple stepped cylindrical structure (counterbore) that achieves the same effect. The recess portion provides torque resistance through its geometry rather than through a complex cross pattern
Data Source
AI summary
A drive transmission device includes a chassis fixed to an apparatus main body and a driving roller that is driven by a driving source. A belt member transmits rotational force of the driving roller. A tension roller contacts the belt member to apply tension to the belt member. A support member supports the tension roller rotatably and is swingable about a rotational shaft of the chassis. A screw fixes the support member to the chassis at a predetermined position. A retaining member is able to be engaged with the chassis, in which the support member is arranged and fixed between a part of the retaining member and the chassis in an insertion direction of the screw.