Auxiliary Valve for Percussive Device Stroke Frequency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fluid-operated percussive devices are limited in their maximum achievable stroke frequency due to geometrical constraints and spool switching time, which restricts the minimization of stroke length and maximization of frequency.
Innovation Solution
Incorporating an auxiliary valve that controls fluid contact between an auxiliary channel and the main valve, allowing the switching signal to be transmitted earlier, thereby reducing stroke length and increasing frequency, with the auxiliary valve actuated by pressure in the rear drive chamber to facilitate higher striking frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spool switching time is minimized and the signal point distance from striking position is reduced, then the stroke frequency is maximized, but the geometrical constraints and spool switching time limitations prevent further increase in frequency
Solution Approach 1:
The valve control system is segmented into a main valve and an auxiliary valve. The auxiliary valve handles the early switching signal transmission, while the main valve handles the primary fluid control. This segmentation allows the spool switching to occur earlier in the stroke cycle without increasing the complexity of the main valve system, thereby increasing stroke frequency.
Solution Approach 2:
The auxiliary valve performs preliminary action by transmitting the switching signal before the percussive piston reaches the end region. This preliminary signal transmission allows the main valve to be prepared in advance for the switching event, reducing the effective spool switching time and enabling higher stroke frequencies.
2Productivity
If the stroke length is reduced to increase frequency, then the striking frequency increases, but the minimal signal point distance and spool switching time create a lower bound on achievable stroke length
Solution Approach 1:
The auxiliary valve transmits the switching signal in advance, before the percussive piston reaches the end region. This preliminary action allows the stroke length to be reduced further than previously possible, as the valve switching is triggered earlier in the stroke cycle, breaking the lower bound constraint on stroke length.
Solution Approach 2:
The auxiliary valve acts as an intermediary between the piston position and the main valve switching. It receives the early position signal and transmits the switching command to the main valve, allowing decoupling of the stroke length from the spool switching time constraint and enabling shorter strokes at higher frequencies.
3Productivity
If an auxiliary valve is added to transmit switching signals earlier, then the stroke frequency increases, but the device complexity increases
Solution Approach 1:
The control function is segmented between the auxiliary valve and main valve. The auxiliary valve is dedicated to early signal transmission, while the main valve maintains its primary control function. This segmentation allows the system to achieve higher frequencies without significantly increasing the complexity of the main control architecture.
Solution Approach 2:
The auxiliary valve, while adding a component, provides multi-functionality by handling both the early switching signal transmission and working in conjunction with the main valve for complete cycle control. This multi-functionality justifies the added complexity by delivering significant performance improvement in stroke frequency.
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 approach enables a significant increase in striking frequency, potentially by up to 50% or more, while allowing for a lighter percussive piston design, as the switching signal is transmitted closer to the rear end position, enabling shorter stroke lengths and higher operational frequencies.
Implementation Method 1
the auxiliary valve is actuated by pressure in the rear drive chamber to facilitate higher striking frequencies
Implementation Method 2
the spool of the main valve starts to switch and move to the right, driven by a permanent, high pressure on the left driving surface of the valve spool
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for controlling a fluid operated percussive device, which inside an axially extending cylinder room (3) of a housing (2) of the percussive device includes a to and fro moveable percussive piston (1), which is adapted for performing strikes in a striking direction (A) and which includes a signal portion (4) for controlling a main valve (5), which is adapted to intermittently transmit pressure fluid to at least one driving chamber (7) for the percussive piston. An auxiliary valve (9) is controlled for transmitting fluid contact between at least one auxiliary channel means (13,14) with a channel opening in the cylinder room (3), and the main valve (5) over the signal portion (4), for switching the main valve (5) before the percussive piston, in operation, has reached at least one of said regions. The invention also concerns a percussive device and a rock drilling machine.