Composite Seal for Hydraulic Hammer Dust Migration
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Solution Overview
Problem
Existing hydraulic hammers face challenges with dust and debris migration due to the central location of seals, which complicates maintenance and increases the risk of seal damage from debris, leading to premature failure and high maintenance costs.
Innovation Solution
A composite seal system is introduced, featuring a rigid exterior cover made of mineral-filled nylon and a flexible interior seal of polyurethane, positioned near the distal end of the housing, with a design that includes a bushing with an inner guide surface and a sealing arm to engage the tool, allowing for easier access and reduced debris impact on the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal is positioned centrally within the housing near internal components, then sealing effectiveness is improved, but maintenance complexity and time increase significantly
Solution Approach 1:
The seal assembly is divided into separate components: a stationary seal portion attached to the housing and a movable seal portion attached to the tool. This segmentation allows the movable seal portion to be accessed and replaced independently by removing only the tool, while the stationary seal portion remains in place, resolving the contradiction between central positioning for sealing effectiveness and accessibility for maintenance.
2Ease of repair
If the seal is located closer to the distal end of the housing, then maintenance access is improved, but the seal becomes more susceptible to damage from debris
Solution Approach 1:
The seal is segmented into stationary and movable portions positioned at different locations. The movable seal portion is located near the distal end for easy access, while the stationary seal portion remains centrally located for protection. This segmentation allows each portion to fulfill its function optimally without the trade-off present in unified seal designs.
Solution Approach 2:
The tool acts as an intermediary element that separates the seal assembly from direct debris exposure. The movable seal portion attached to the tool is protected by the tool's position, while still allowing maintenance access by simply removing the tool. This intermediary positioning resolves the contradiction between accessibility and debris protection.
3Reliability
If a soft flexible seal material is used to improve sealing engagement, then sealing effectiveness increases, but susceptibility to tearing and ripping from debris impacts increases
Solution Approach 1:
Different portions of the seal have different material properties: the stationary seal portion uses a harder, more debris-resistant material for protection, while the movable seal portion uses a softer, more flexible material for effective sealing engagement with the tool. This local differentiation of material quality resolves the contradiction between sealing effectiveness and debris damage resistance.
Solution Approach 2:
The seal assembly uses composite construction with different materials for different functions. The stationary portion employs harder materials like hardened steel or ceramic for debris resistance, while the movable portion uses flexible materials like rubber or polymer for sealing. This composite approach allows each material to optimize its properties for its specific function, resolving the contradiction between softness for sealing and hardness for durability.
Data Source
AI summary
A hydraulic hammer (14) may include a housing (30) having a distal end defining an opening (38), a bushing (54) positioned adjacent the housing distal end, the bushing (54) having an inner guide surface (58) and a distal end (56), and a tool (22) having a proximal section (60) slidably disposed in the bushing inner guide surface (58) and a distal section (62) projecting from the housing (30) through the opening (38). The hydraulic hammer (14) may further include a composite seal (70) having an exterior cover (72) with a proximal end (76) releasably coupled to the bushing (54) and a distal end (77) projecting from the distal end (56) of the bushing (54), the exterior cover distal end (77) defining a recess (90) opening toward the tool (22), and an interior seal (74) having a base (92) disposed in the exterior cover recess (90) and a sealing arm (94) projecting inwardly from the base (92), the sealing arm (94) being configured to sealingly engage the tool (22).