Hydraulic Piston Centering to Prevent Percussion Apparatus Seizing
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Solution Overview
Problem
Percussion apparatuses with high mass striking pistons experience seizing issues due to intense friction between the piston and guide surfaces, especially when not used in a vertical position, leading to blockages or damage, and existing hydraulic flow arrangements fail to ensure proper centering.
Innovation Solution
A percussion apparatus with a centering device featuring centering chambers connected to a high pressure fluid supply and discharge grooves connected to a low pressure circuit, which creates a hydraulic clearance to prevent direct contact between the piston and guide surfaces, ensuring effective recentering and preventing seizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high mass striking piston is used, then the striking force is improved, but the risk of seizing due to intense friction increases
Solution Approach 1:
The patent applies hydraulic principles by introducing a hydraulic film between the striking piston and guide surfaces through controlled fluid flow. High pressure fluid is supplied to create this hydraulic film that separates the piston from the guide surfaces, eliminating direct metal-to-metal contact and preventing seizing while allowing the use of high mass pistons for increased striking force.
Solution Approach 2:
The hydraulic film acts as an intermediary substance between the striking piston and guide surfaces. This fluid medium prevents direct contact between the piston and guide surfaces, reducing friction and preventing seizing. The fluid serves as a mediator that allows the high mass piston to operate smoothly without direct mechanical contact.
2Reliability
If hydraulic flow is created by pressure differential at axial ends of guide surfaces, then friction is reduced, but proper centering of the striking piston is not ensured
Solution Approach 1:
The patent applies local quality by creating different flow conditions in different regions of the guide surfaces. The circumferential grooves are strategically positioned to create localized hydraulic flow patterns that not only reduce friction but also generate hydrodynamic forces that actively center the piston. The grooves are located at specific positions to optimize both friction reduction and centering functions simultaneously.
Solution Approach 2:
The hydraulic flow system is designed to be dynamic, with the hydraulic film thickness and flow patterns automatically adjusting based on piston position and operating conditions. The circumferential grooves create a dynamic hydrodynamic effect that actively responds to piston displacement, generating restoring forces that continuously center the piston 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 solution effectively prevents seizing of the striking piston by maintaining hydraulic clearance and ensuring proper centering, even with high mass pistons, regardless of the apparatus's position, thereby preventing damage and ensuring smooth operation.
Implementation Method 1
a high pressure fluid supply circuit and a low pressure circuit, a centering device configured to center the striking piston in the piston cylinder, the centering device comprising: a plurality of centering chambers formed in the guide surface and distributed around the striking piston, each centering chamber being fluidly connected to the high pressure fluid supply circuit
Implementation Method 2
two discharge grooves formed in the guide surface, each discharge groove being located proximate to the centering chambers and being fluidly connected to the low pressure circuit, the two discharge grooves being annular and extending around the striking piston and respectively on either side of the centering chambers
Implementation Method 3
Such a configuration of the percussion apparatus, and in particular of the centering device, makes it possible to hydraulically and effectively recenter the striking piston and thus to prevent the latter from coming into direct contact with its guide surface
Data Source
AI summary
This percussion apparatus includes a striking piston mounted so as to be displaced inside a piston cylinder and arranged to strike a tool; and a guide bearing comprising a guide surface configured to guide the striking piston during the displacements of the striking piston in the piston cylinder. The guide bearing includes a centering device configured to center the striking piston in the piston cylinder, the centering device comprising centering chambers formed in the guide surface and distributed around the striking piston, each centering chamber being fluidly connected to a high pressure fluid supply circuit; and at least one discharge groove formed in the guide surface of the guide bearing and located proximate to at least one of the centering chambers, the at least one discharge groove being fluidly connected to a low pressure circuit.