Flow Diversion Sub for Down-the-Hole Drill Hammer
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Solution Overview
Problem
In down-the-hole drilling, the circulation process causes unnecessary wear to the drill bit due to uncontrolled rotation of the drill hammer and bit when not actively drilling, as the motor continues to rotate and direct airflow through the system even when not engaged with the rock surface.
Innovation Solution
A flow diversion sub that redirects up to 100% of the motor and hammer flow away from the motor and hammer during circulation, acting as a three-way valve to prevent airflow through the drill bit during non-drilling modes, thereby stopping the motor and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor continues to rotate during circulation to clean spoils and cuttings, then the circulation process is effective, but the drill bit suffers unnecessary wear and damage due to uncontrolled rotation
Solution Approach 1:
A flow diversion sub is introduced as an intermediary device between the motor and the drill bit. This sub includes a housing with a flow passage and a diverting member that can redirect flow away from the motor-hammer assembly. The diverting member acts as a mediator that controls whether flow reaches the motor, thereby preventing unwanted rotation during circulation while maintaining circulation effectiveness.
Solution Approach 2:
The flow diversion sub employs a movable diverting member that can dynamically switch between two positions: one where flow passes through the motor to enable rotation during drilling, and another where flow is redirected away from the motor to prevent rotation during circulation. This dynamic adjustment allows the system to adapt its behavior based on the operational mode.
2Reliability
If the drill bit is protected from uncontrolled rotation during circulation, then wear is minimized, but the system requires additional complexity to control flow direction
Solution Approach 1:
The flow diversion sub utilizes the existing circulation flow itself to actuate the diverting member. When circulation flow is present, it automatically pushes the diverting member to the position that blocks flow to the motor, preventing rotation. During drilling, the operator can manually position the diverting member to allow flow through. This self-service mechanism reduces the need for additional complex control systems.
Solution Approach 2:
The flow diversion sub extracts the flow control function from the main motor-hammer assembly and places it in a separate, dedicated component. This modular approach isolates the complexity into a discrete unit that can be easily controlled and maintained, rather than integrating complex control mechanisms into the motor itself.
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
Prevents detrimental wear to the drill bit by stopping the motor and redirecting airflow during circulation, ensuring the drill bit remains protected and operational when not actively drilling, while allowing controlled flow when necessary.
Implementation Method 1
One of the housing assembly and drive shaft moves between a first position and a second position relative to the other of the housing assembly and drive shaft. In the first position the upper central blind hole is in fluid communication with the lower central blind hole, and in the second position the upper central blind hole is at least partially blocked from being in fluid communication with the lower central blind hole.
Data Source
AI summary
A flow diversion sub for a down-the-hole drill comprising a housing assembly that includes a housing body, a cap extending from the housing body, and a drive shaft having an upper central blind hole and a lower central blind hole spaced from the upper central blind hole, wherein the drive shaft is received within the housing assembly. In operation, one of the housing assembly and drive shaft moves between a first position and a second position relative to the other of the housing assembly and drive shaft. In the first position the upper central blind hole is in fluid communication with the lower central blind hole, and in the second position the upper central blind hole is blocked from being in fluid communication with the lower central blind hole.