Pulley End Cap Ventilation Path for Pressure Balance
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Solution Overview
Problem
The existing pulley structures in auxiliary machine driving units are prone to corrosion and premature failure due to the infiltration of aqueous media, such as muddy water, which leads to grease leakage and reduced lifespan, as the end cap's sealing properties are inadequate, causing pressure differences that result in bearing grease leakage.
Innovation Solution
A pulley structure design featuring a cylindrical first rotating body with a torsion coil spring and a second rotating body, where a ventilation path is formed in the end cap to prevent aqueous media infiltration, ensuring communication between the spring accommodation space and the outside only through this path, maintaining pressure balance and preventing grease leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end cap blocks the opening portion completely to prevent aqueous media infiltration, then sealing performance is improved, but pressure balance is disrupted causing bearing grease leakage
Solution Approach 1:
The end cap is designed with differentiated local properties: most of the opening portion is blocked to prevent aqueous media infiltration, but a specific local region contains a through-hole to maintain pressure balance. This allows the end cap to simultaneously achieve sealing performance and pressure equilibrium, preventing bearing grease leakage while blocking corrosive substances.
2Duration of action of stationary object
If the end cap is made fully sealed to prevent corrosion, then component lifespan is extended, but pressure difference causes grease to leak out
Solution Approach 1:
The end cap employs local quality by being selectively sealed: the majority surface blocks aqueous media to prevent corrosion and extend component lifespan, while a localized through-hole maintains pressure balance to prevent grease leakage. This differentiated sealing approach resolves the contradiction between corrosion prevention and grease retention.
3Device complexity
If the ventilation path is positioned at the center, then structural symmetry is maintained, but aqueous media can easily infiltrate through the path
Solution Approach 1:
The ventilation path is deliberately positioned asymmetrically at an outer region of the end cap rather than at the center. This asymmetric placement maintains structural simplicity while effectively preventing aqueous media infiltration, as the path is positioned where corrosive substances are less likely to reach during operation.
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
The design effectively prevents aqueous media from entering the spring accommodation space, reduces the risk of corrosion and foreign substance jamming, and extends the lifespan of the pulley structure by maintaining pressure balance and ensuring reliable sealing.
Implementation Method 1
a torsion coil spring which is accommodated in a spring accommodation space formed between the first rotating body and the second rotating body
Implementation Method 2
a contact seal member disposed on both sides of the plurality of balls. The contact seal member is formed of a rubber-like elastic body and sheet metal. An outer circumferential edge of the contact seal member is fixed to the outer wheel, and a lip portion formed at an inner circumferential edge of the contact seal member comes into contact with a sealing surface of the inner wheel
Implementation Method 3
a rolling bearing provided to be interposed between the first rotating body and the second rotating body on the other side in the rotating axis direction
Data Source
Figure 1
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Figure 3
AI summary
This pulley structure (1) has an air passage (10) which is formed at a position offset radially from the rotation axis of a first rotating body (2) and which connects a spring accommodation space (8) and the outside, the spring accommodating space (8) being formed between the first rotating body (2) and a second rotating body (3). At least a part of the air passage (10) is formed in an end cap (5) for closing an opening (21) of the first rotating body (2), the opening (21) being located on one side of the first rotating body (2) in the rotation axis direction. The end cap (5) closes the opening (21) of the first rotating body (2) so that the spring accommodation space (8) is not in communication with the outside toward the one side in the rotation axis direction except through the air passage (10).