Closed-Loop Hydraulic DTH Hammer With Flushing-Assisted Piston Drive
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Solution Overview
Problem
Existing hydraulic down-the-hole hammers face inefficiencies due to energy loss in flushing fluid and the need for a secure arrangement of the control valve within the shaft.
Innovation Solution
A closed-loop hydraulic down-the-hole hammer design incorporating a supplementary rear drive chamber for flushing fluid to assist piston propulsion, and a control valve housing retained by a taper lock mechanism using an annular flange and tapered surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a separate flow of flushing fluid is provided to flush cuttings from the hole, then cuttings are effectively removed, but much of the energy used to deliver the flushing fluid is lost
Solution Approach 1:
The patent combines the flushing fluid delivery system with the hydraulic drive system by integrating the flushing fluid supply into the rear drive chamber. The flushing fluid flows through the rear drive chamber to assist in driving the piston during the upward stroke, merging the previously separate flushing function with the driving function. This eliminates the energy loss associated with separate flushing fluid delivery while maintaining effective cuttings removal.
Solution Approach 2:
The patent converts the previously wasted energy in the flushing fluid into a useful driving force. By routing the flushing fluid through the rear drive chamber, the energy that would have been lost is now harnessed to assist in driving the piston upward, transforming a harmful energy loss into a beneficial contribution to the drilling process.
2Ease of operation
If the control valve is arranged within a central bore of a shaft, then the valve can be inserted and controlled, but an opening at one end of the shaft is required which compromises structural integrity
Solution Approach 1:
The patent nests the control valve within the central bore of the piston, which itself is nested within the shaft assembly. The control valve housing is positioned within the central bore, creating a nested arrangement that allows the valve to be installed and operated without compromising the shaft's structural integrity. The piston acts as an intermediate container that houses the valve while maintaining the shaft's strength.
Solution Approach 2:
The patent introduces the piston as an intermediary element between the shaft and the control valve. The piston's central bore provides the necessary passage for the control valve, while the piston itself maintains the structural integrity of the assembly. This intermediary structure allows the control valve to be installed without creating weak points in the shaft.
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
Enhances efficiency by utilizing flushing fluid energy for piston driving and securely retains the control valve during operation, reducing energy loss and ensuring operational stability.
Implementation Method 1
a supplementary rear drive chamber arranged to receive a separate flow of fluid to that supplied to the forward and rear drive chambers
Implementation Method 2
a control valve housing having a tapered outer surface at a forward portion thereof; an annular flange or bushing connected to the shaft and having a tapered inner surface, corresponding in shape to and engageable with the tapered outer surface of the control valve housing
Data Source
AI summary
The present invention relates to a closed-loop 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, wherein forward and rear drive chambers for the piston are disposed between the piston and the shaft and wherein 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 further comprises an outer wear sleeve, wherein the piston is housed within the outer wear sleeve. A supplementary rear drive chamber is disposed internally of the outer wear sleeve. According to another aspect of the invention, the hammer comprises a control valve housing, disposed at least partially within the central bore of the shaft at a forward end of the shaft and arranged to receive the control valve, the control valve housing having a tapered outer surface at a forward portion thereof and an annular flange connected to the shaft and having a tapered inner surface, corresponding in shape to and engageable with the tapered outer surface of the control valve housing, whereby the control valve housing is retained in the shaft by the annular flange. The hammer further comprises engagement means on the control valve housing slidably engageable with complementary engagement means on the shaft to prevent relative rotation therebetween.