Valve Timing Adjustment Device Axial Deformation Control
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Solution Overview
Problem
Existing electric valve timing adjustment devices for internal combustion engines face issues with slidability deterioration between rotatable bodies due to axial force-induced deformation when fixed to drive and driven shafts, leading to reduced performance and reliability.
Innovation Solution
The valve timing adjustment device includes a fastening portion with a through-hole for bolt fixation, a slide portion with a cross-axial slide surface, and a bearing portion that limits deformation influence, ensuring the driven-side rotatable body's fastening, slide, and bearing components maintain slidability and wear resistance by projecting the fastening portion on the drive shaft side, thereby minimizing deformation and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the valve timing adjustment device is fixed to the drive shaft or driven shaft with a bolt, then the device can be securely mounted and transmit rotational motion, but axial force-induced deformation occurs at the fastening portion, deteriorating slidability between rotatable bodies
Solution Approach 1:
The rotatable body is divided into distinct functional portions: a fastening portion for bolt fixation, a slide portion for maintaining slidability, and a bearing portion for rotational support. This segmentation isolates the deformation effect to the fastening portion while protecting the slide and bearing portions from deformation, thereby resolving the contradiction between secure fastening and maintained slidability
Solution Approach 2:
The bearing portion acts as an intermediary element between the fastening portion and the slide portion. It transmits the rotational motion while supporting the slide portion, preventing deformation from the fastening portion from directly affecting the slidability-critical surfaces. This intermediary structure allows strong fastening without compromising sliding performance
2Reliability
If the fastening portion is positioned to ensure secure mounting, then mounting reliability is improved, but deformation from axial forces affects the slide surface, increasing friction and wear
Solution Approach 1:
By segmenting the rotatable body into fastening, slide, and bearing portions with distinct functions, the design isolates the harmful deformation effects to the fastening portion. The slide portion maintains its geometric integrity, preventing increased friction and wear while the fastening portion provides secure mounting
Solution Approach 2:
Different portions of the rotatable body are given different structural characteristics optimized for their specific functions. The fastening portion is designed to withstand axial forces, the slide portion maintains smooth surfaces for low friction, and the bearing portion provides rotational support. This local optimization ensures mounting reliability without compromising against friction and wear
Data Source
AI summary
A valve timing adjustment device includes: a first rotatable body that is rotated about a rotational axis synchronously with one of a drive shaft and a driven shaft of an engine; and a second rotatable body that is rotated about the rotational axis synchronously with the other one of the drive shaft and the driven shaft. The first rotatable body includes: a fastening portion, a slide portion and a bearing portion. The fastening portion is fastened to the one of the drive shaft and the driven shaft. The bearing portion includes an outer peripheral surface that is opposed to an inner peripheral surface of the second rotatable body, and the bearing portion rotatably supports the second rotatable body. The fastening portion projects on one axial side of the slide portion and the bearing portion in an axial direction toward the one of the drive shaft and the driven shaft.