Multi-Accumulator Hydraulic Percussion Mechanism
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Solution Overview
Problem
Hydraulic down-the-hole hammers face limitations in accumulator performance due to limited storage capacity, response time, and reliability, which restrict the maximum speed and blow energy of percussion mechanisms, especially at high frequencies, and are exacerbated by the constrained size and shape of the drill tool.
Innovation Solution
A hydraulically powered percussion mechanism featuring a plurality of accumulator elements in a common housing, arranged equidistant from the piston, with each element's primary direction of movement parallel to the mechanism's longitudinal axis, and positioned proximate to the shuttle valve to minimize fluid path length and reduce 'fluid hammer' effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single accumulator is used in down-the-hole hammers, then the device complexity is reduced, but the storage capacity and reliability are limited
Solution Approach 1:
The accumulator assembly is segmented into multiple accumulator elements (first accumulator element, second accumulator element, third accumulator element, fourth accumulator element) arranged in a common housing. Each element has its own piston and chamber, allowing independent operation. This segmentation increases total storage capacity while maintaining manageable complexity through modular design.
2Speed
If the accumulator is placed remote from the shuttle valve, then the fluid volume in motion is reduced, but the response time decreases and fluid hammer effects increase
Solution Approach 1:
The accumulator elements are arranged radially around the central piston axis in a multi-dimensional configuration. This spatial arrangement minimizes the radial distance fluid must travel between the shuttle valve and accumulator elements, reducing response time and minimizing pressure fluctuations while maintaining compact dimensions suitable for down-the-hole hammer constraints.
3Productivity
If the accumulator pre-charge pressure is increased to improve fluid delivery speed, then the maximum piston speed increases, but the risk of damaging pressure fluctuations increases
Solution Approach 1:
The accumulator elements are pre-charged with gas at controlled pressures to create a cushioning effect. This pre-charge pressure is optimized to enable rapid fluid delivery to maintain high piston speeds and impact frequency, while the gas cushion absorbs and dampens pressure fluctuations, preventing damaging fluid hammer effects during rapid deceleration and direction changes.
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
This configuration enhances storage capacity, reliability, and response time, allowing for increased blow energy and impact frequency, while minimizing the risk of damaging pressure fluctuations and optimizing performance within the constraints of the down-the-hole drill tool.
Implementation Method 1
An accumulator to take in, store, and deliver back pressurised hydraulic fluid to accommodate the varying instantaneous flow requirements created by the reciprocation of the piston
Implementation Method 2
The fluid is fed to the shuttle valve and the accumulator in parallel. Depending on the position of the piston in the cycle, the hydraulic fluid can either pass through the shuttle valve to move the impact piston, or can fill the accumulator
Data Source
AI summary
The present invention relates to a hydraulically powered percussion mechanism (12), comprising a piston (6) to impact a percussion bit (8). The percussion mechanism also includes a first accumulator assembly (3a) for hydraulic fluid. The first accumulator assembly comprises a plurality of first accumulator elements (27). In a first aspect, the plurality of first accumulator elements are arranged in a common housing (14). In a second aspect, each of the first accumulator elements is arranged at the same proximity to the piston. In a third aspect, each of the first accumulator elements comprises an accumulator membrane (32) or piston, and wherein the primary direction of movement of the membrane or piston in contact with the hydraulic fluid is substantially parallel to a longitudinal axis of the mechanism.