Hydraulic DTH Hammer Piston Valve Nesting
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Solution Overview
Problem
Conventional hydraulic down-the-hole hammers suffer from pressure wave generation, pressure losses, inefficient accumulator operation, and complex design due to long flow channels and valve positioning, while water-powered hammers face issues with inefficient piston cross-sectional area and impractical length.
Innovation Solution
A hydraulic down-the-hole hammer design with a control valve within the piston, minimizing fluid travel distance, reducing pressure losses, and eliminating pressure waves, combined with a disposable piston that forms part of the load-bearing element, allowing efficient drilling and installation of subsea piles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the control valve is positioned at the rear end of the piston, then the hammer structure is conventional and easier to manufacture, but the flow channel length increases causing pressure waves, pressure losses, and inefficient accumulator operation
Solution Approach 1:
The control valve is relocated from the rear end of the piston to the central bore of the piston, changing the spatial dimension of valve positioning. This dimensional shift reduces the flow channel length from the valve to the drive chambers, eliminating pressure waves and reducing pressure losses while maintaining manufacturing feasibility.
Solution Approach 2:
The control valve is nested within the central bore of the piston, placing the valve inside the piston structure rather than at its external rear end. This nesting arrangement minimizes the distance between the valve and the drive chambers, reducing fluid travel distance and associated energy losses.
2Ease of manufacture
If the accumulators are positioned upstream of the control valve, then the accumulator placement is conventional, but the communication delay between accumulators and piston is substantial due to long flow channels
Solution Approach 1:
The accumulators are repositioned from upstream of the control valve to downstream of the valve, changing their spatial arrangement relative to the valve. This dimensional reconfiguration shortens the flow channel between the accumulators and the piston, reducing communication delay and improving response time.
Solution Approach 2:
The accumulators are positioned downstream of the control valve so that they can more directly and quickly supply pressurized fluid to the drive chambers when needed. This preliminary positioning reduces the delay in fluid communication, allowing the accumulators to respond more rapidly to piston requirements.
3Adaptability or versatility
If the piston cross-sectional area is reduced to minimize non-driving area, then water-powered operation becomes feasible, but the piston becomes too lightweight for effective drilling requiring increased length
Solution Approach 1:
The piston is segmented into distinct functional zones: a driving end with sufficient cross-sectional area for effective water-powered operation, and a extended rear portion providing additional weight. This segmentation allows the piston to achieve the necessary weight for drilling while maintaining an optimized driving area for water-powered operation.
Solution Approach 2:
Different portions of the piston have different cross-sectional areas optimized for different functions. The forward driving end has a smaller cross-sectional area suitable for water-powered operation, while the rear portion has increased cross-sectional area to provide sufficient weight. This local variation in quality allows the piston to satisfy both operational requirements.
4Loss of energy
If a central bore is provided through the piston for fluid communication, then pressure losses are reduced, but the piston requires larger bore size which further reduces effective cross-sectional area and increases length requirements
Solution Approach 1:
The fluid communication function is extracted from the piston bore and relocated to the control valve positioned in the central bore. By taking out the fluid communication pathway from the main piston structure and positioning it at the valve, the system reduces pressure losses without requiring a large central bore that would compromise piston cross-sectional area and increase length.
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 new design reduces pressure losses, eliminates harmful pressure waves, and enables faster, cost-effective installation of subsea piles in various seabed conditions, including rocky terrain, using disposable hammers that form part of the load-bearing element.
Implementation Method 1
A hydraulic down-the-hole hammer comprises an elongate shaft; a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit
Implementation Method 2
an impact piston to impart percussion energy to a drill bit or tool located at a forward end of the hammer
Data Source
Figure 1~2
Figure 3~4
Figure 5~6a
AI summary
The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongate shaft and a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit. Forward and rear drive chambers for the piston are disposed between the piston and the shaft and the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore. The hammer also comprises a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston. The hammer may be a disposable water hammer in which the piston is an outermost component of the hammer. The invention also relates to a method and system for installing a load-bearing element in a seabed, a method and system for installing a subsea anchor on a seabed, a subsea pile and a subsea anchor.