Tool driving or impacting – Drive controlled by relative axial movement of tool – Drive motor controlled
Patent
1995-02-17
1996-06-18
Smith, Scott A.
Tool driving or impacting
Drive controlled by relative axial movement of tool
Drive motor controlled
173207, E02D 710
Patent
active
055268854
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to construction machines, and, particularly, to a hydraulic device for driving piles.
DESCRIPTION OF THE ART
Known in the art is a hydraulic device for driving piles, comprising a housing, accommodating a striker mounted with a possibility of reciprocating therein and interacting with an anvil block mounted coaxially therewith in the housing (DE, A,2 900221). Mounted on the housing coaxially to the striker is a hydraulic power cylinder whose rod is connected to the striker with its one end, whereas the other end thereof is connected to the piston which divides the hydraulic power cylinder into a rod end and a head end. The rod end is in constant communication with a pressure flow line. The head end through a spool-type hydraulic directional control valve alternatively communicates with a pressure flow line and a return flow line.
The control unit of the hydraulic directional control valve comprises a pilot cylinder defined by the internal surface of the spool space which communicates through a pressure relief valve with the return flow line, and a plunger mounted in this space and adapted for reciprocating therein, one end of the plunger interacting with the rod of the power cylinder.
The known hydraulic device for pile driving is highly reliable and durable. However, in the structure disclosed the instant of reversal in the lower position with respect to the instant of collision of the striker and the anvil block cannot be exactly registered and adjusted, which makes the instant of switching with respect to the stroke position unstable, and consequently, reduces the efficient use of the kinetic energy of the striker, and the effect of pile driving.
Moreover, the adjustment of the impact energy performed using additional means, for instance, electromagnetic device for changing the stroke length of the accumulating cylinder piston, and therefore, volume of the accumulating cylinder. This is done on command of the operator, that is, manually; this cannot provide an optimum energy impact for an adequate operation of the device, which reduces its efficiency.
As is known, the spool-type systems require precision machining of rather large surfaces of the members to be joined and are not adapted for use of low-viscosity liquids as a working fluid, such as, for example, water, so as to avoid an inadmissible increase in leaks.
Moreover, the use of the spool-type directional control valve causes "short-circuiting" of power cylinders, that is, with the spool in a definite position, the head end and the rod end of the power cylinder appear in communication with each other, which causes loss of the working fluid and reduces the efficiency of the hydraulic drive by 20-25%.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hydraulic device for driving piles having such a structure of the directional control selector that considerably increases the efficiency of the pile driving operation and renders it possible to use, as a working fluid, low-viscosity liquids, preferably water, while enhancing the efficiency of the device.
The object of the invention is accomplished in a hydraulic device for driving piles, comprising a housing accommodating, with a possibility of reciprocating, a striker interacting with an anvil block coaxially arranged in the housing, and a hydraulic power cylinder installed on the housing coaxially with the striker. The rod of the power cylinder is connected with one its end to the striker, and with the other end, to the piston which divides the hydraulic power cylinder interior into a rod end which is in constant communication with a pressure line, and a head end which is in alternating communication with the rod end and a return flow line through a hydraulic directional control selector. The control selector has a control unit which comprises a pilot cylinder having its interior in communication with the return flow line through a pressure relief valve, and a plunger installed in the interior of the pilot cylinder for
REFERENCES:
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patent: 3207043 (1965-09-01), Kay
patent: 3608650 (1971-09-01), Matsusaka
patent: 4052107 (1977-10-01), Hay
patent: 4429751 (1984-02-01), Jackson et al.
patent: 5117921 (1992-06-01), Bartels et al.
patent: 5152352 (1992-10-01), Mandanis
Ermolaev Vladimir M.
Goldobin Vyacheslav A.
Kuvshinov Viktor A.
Rusin Sergei V.
Aktsionernoe obschestvo zakrytogo tipa "Rossiiskaya Patentovanna
Smith Scott A.
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