Rotary Joint Device Reducing Rotational Resistance
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Solution Overview
Problem
Rotary joint devices with multiple seal members for fluid communication between a rotating shaft and an outer cylinder face high rotational resistance, leading to increased load on driving devices, which necessitates large and costly motors due to the need for high output power to counteract friction and maintain fluid pressure.
Innovation Solution
A rotary joint device design featuring an outer cylinder composed of cylindrical blocks with precision-machined attachment grooves and positioning blocks to ensure accurate reassembly, reducing the number of seal members and minimizing diametrical clearance between the outer cylinder and rotating shaft, thereby reducing rotational resistance and maintaining fluid pressure without increasing motor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple seal members are provided for each port to prevent fluid leakage, then fluid pressure is maintained, but rotational resistance increases and load on driving device increases
Solution Approach 1:
The patent removes seal members from the connection between the outer cylinder and rotating shaft. Instead of using multiple seal members as in conventional technology, this invention relies on the precision-machined diametrical clearance (0.005mm or less) to prevent fluid leakage without requiring seal members, thereby eliminating the rotational resistance caused by seal friction.
Solution Approach 2:
The patent changes the critical parameter from seal member configuration to diametrical clearance dimension. By precisely controlling the clearance between the outer cylinder inner peripheral surface and rotating shaft outer peripheral surface to be 0.005mm or less, the system achieves fluid sealing without mechanical seals, resolving the contradiction between reliability and rotational resistance.
2Power
If high output power motor is used to counteract rotational resistance, then driving capability is improved, but device size and manufacturing cost increase
Solution Approach 1:
The patent converts the potential harm of tight clearance (which could cause friction and wear) into a benefit by using the precise 0.005mm clearance to eliminate seal members entirely. This conversion reduces rotational resistance to minimal levels, allowing the use of smaller motors and reducing overall device complexity while maintaining driving capability.
3Reliability
If diametrical clearance is reduced to maintain fluid pressure, then fluid leakage is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes a specific parameter threshold (0.005mm diametrical clearance) that balances fluid sealing effectiveness with manufacturing feasibility. This precise parameter control replaces the need for complex seal member assemblies, achieving reliable fluid leakage prevention while maintaining reasonable manufacturing precision requirements.
4Force
If seal members are reduced or eliminated to reduce rotational resistance, then load on driving device is reduced, but fluid pressure maintenance becomes difficult
Solution Approach 1:
The patent uses precise parameter control (0.005mm diametrical clearance) to replace seal members entirely. This parameter optimization achieves both goals: eliminating seal-related rotational resistance while maintaining fluid pressure through the precision clearance itself, which prevents fluid leakage without requiring mechanical seals.
Data Source
AI summary
A rotary joint device includes attachment grooves formed at positions in an outer peripheral surface of an outer cylinder, each attachment groove being formed so as to straddle a pair of adjacent cylindrical blocks and so as to be exposed from the outer peripheral surface of the outer cylinder, each attachment groove having a bottom surface that is machined to form a flat surface in a state in which the cylindrical blocks are combined, and positioning blocks corresponding to the attachment grooves on a one-to-one basis and each having an attachment phase that is uniquely set to a corresponding one of the attachment grooves in the axial direction and in a circumferential direction of the outer cylinder, each positioning block having an attachment surface corresponding to the bottom surface of a corresponding one of the attachment grooves, the attachment surface being machined so as to form a flat surface.