Note: Descriptions are shown in the official language in which they were submitted.
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"AN HYDRAULIC XAM~ER~
INTRODUCTION TO THE_INVENTION
This invention relates to an hydraulic hammer assembly
used in jack hammers and drilling machines,
particularly but not exclusively, down-the-hole
drilling machines. ~-~
BACRG~OUND Ol~ THE INVENTION
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Conventional hydraulic hammers utilise a high pressure
pump and~ reservoir with fluid from the pump passed
through a pressure operated valve which directs ~low to
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one or other side of a piston in a piston and cylinder
assembly. The piston forms t~e hammer for striking the
drill bit.
There must be means for connecting the pump to the
hammer and to return the hydraulic fluid, usually oil,
back to the reservoir. This is usually a high pressure
flexible hydraulic hose. A hose of this type cannot be
used in down-the hole hammer assemblies.
It is an object oP the present invention to provide an
hydraulic hammer which does not require an internal
valve to control flow direction of the fluid passid the
piston.
SUMMARY OF THE INVENTION
According to this invention there is provided an
hydraulic hammer assembly comprising a piston and
cylinder assembly with means for applying intermittent
hydr~ulic pressure to one side of the piston and
compressible means for constantly applying pressure to
the opposite side of the piston.
JThe invention
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The invention al30 provide~ the compressible means tobe mechanically supplied by mean~ of a spring or the
like or alternatively through a compressible fluid.
The intermittent hydrauli~ pressure can be supplied
through an intermittently operated valve controlling a
supply o~ fluid under substantially constant pressure.
Further features of this invention provide for the
valve to be a rotary valve or a sliding valve and for
there to be included means for rotating the hammer
anvil.
Still further features of this invention provide for
the hammer assembly to be part of a down-the-hole drill
with the pressures applied to the piston provided by
fluid transported through separate passages in the
drill rods, for the intermittent pressure fluid to be
used for flushing the drill bit or ~or the intermittent
pressure to be supplied through two different fluids.
In the latter ~ase a second piston slidably operating
in a sleeve will be provided.
~The invention
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The invention also provides for th~ constant pressure
supply fluid to be used for flushing the drill bit in
an assembly as defined above.
BRIEF D~8CRIPTION_O~ THE DRAWING~3
These and other features of this invention will become
apparent from the following descripkion of some
examples of the invention wherein reference will be
made to the accompanying drawings in which
Fig 1 is a longitudinal section through a
down-the-hole drill assembly;
Figs 2 and 3 show modifications to the assembly of
Figure l;
Figs 4 and 5 show alternative valve assemblies for
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the intermittent fluid pressure supply and
Fig 6 shows one form of drill rod suitable for use
with the down-the-hole drill described.
/DETAILED DESCRIPTION
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~ETATLED ~E8CRIPTI~Ie_pY_~ W~
As illustrated in Figure 1 the hammer assembly 1 has a
bit 2 at the free end and a backhead 3 secured to a
drill rod 4. A casing 5 extends between the backhead 3
and the bit 2 which has a passage 6 for flushing fluid
to pass through.
The casing 5 houses an inner sleeve 7 and a hammer in
the form o~ a piston 8. The backhead end of the piston
8 extends as a stem 9 from the remainder of the piston
and engages in the backhead 3 to form a sliding seal
therewith.
The bore 10 through the backhead 3 is co-axial with a
pressure fluid passage 11 in the drill rod 4.
The drawing al50 shows passages formed in the hammer
assembly for flushing fluid which can conveniently be
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compressed air. The passages extend as shown at 12
through the backhead 3, and as shown at 13 between the
casing 5 and inner sleeve 7 extending between the
backhead 3 and bit 2. Apertures 14 are provided through
the bit end of the inner slePve 7 and the outer end of
~ /passage 12
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passage 12 communicates with a passage 15 in the drill
rod 4 for the supply of compressed air.
The compressed air can be supplied at constant pressure
throu~h the passages and apertures above described to
act on the bit striking surface 16 of the piston 8 to
constantly tend to raise the piston 8 from and to the
~it 2.
When the piston 8 is raised from the bit 2 khe
compressed air can also act as a flushing fluid through
the passage 6.
A chamber 17 is formed in the inner sleeve 7 around the
stem 9 of the piston 8. The chamber 17 communicates
through a passage 18 in the backhead 3 to ambient
atmosphere.-
A pressure fluid 19 acts through the bore of the drillrod 4 and backhead 3 as described below to enable the
hammer assembly to operate.
The passage 18 to atmosphere is provided to prevent a
build up of pressure in the chamber 17 which could
/occur if
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occur i~ there is leakage either from the compressed
air path through the assembly or of the pressure fluid
passed the stem 9 of piston 8.
Figure 2 illustrates the inclusion of a second piston
s.eparating the pressure ~lu:id 19 column into two
sections thus enabling two different types of ~luid to
be used.
Figure 3 illustrates a further modification wherein a
gas accumulator is formed by a stem 21 on the striking
end of piston 8 in sliding engagement with a sealing
bush 22 providing an oil filled chamber 23 which is in
communication with the passages 13 between inner sleeve
7 and casing 5. These passages are sealed at the
backhead end.
With gas under pressure introduced into passage 13
movement of the piston will enable the gas to expand or
compress and always provide a pressure on the piston 8
tending to lift the piston 8 from the bit 2.
Flushing medlum in this construction can be provided by
the pressure fluid l9 passing through an axial bore 24
/through the
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throuqh the piston 8 ~nd prefer~bly a restriction 25 in
the form of a suitable plug is provided in the bore 24
to limit the flow o~ pressure fluid 19 to the bit.
To enable the pressure fluid 19 to act intermittently
on the piston 8 with a greater force than that provided
by the compressed gas in passage 13 a pressura pump
~not shown) and valve assembly are provided at the
drill head.
Suitable valves are illustrated in Figures 4 and 5 of
the drawings.
Referring firstly to Figure 4 the valve assembly 26
consists of a valve body 27 which has a passage 28
closed at one end 29 which is connected to a motor 30
for rotation. The open end of the valve is in alignment
with the fluid passage 11 in the drill rod 4.
The body 27 rotates in a valve housing 31 which has a
high pressure inlet port 32 from the pressure pump and
~ an outlet port 33 connected to the reservoir for fluid
for the pump.
~ /The body
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The body 27 hai3 a radial port 34 through the wall
thereof and rotation of body 27 by the motor 30 in the
housing 31 will bring port 34 alternately into
alignment with ports 3~ and 33. This has the result, in
operation, of pressure of.the pressure fluid down the
drill rods intermittently varying from maximum pump
pressure to exhaust pressure. Each time maximum
pressure is exerted down the column of pressure fluid
19 the constant gas pressure acting in the oppositP
direction on piston 8 is overcome and piston 8 is
caused to strike the inner end of the bit 2. When the
pump pressure on the pressure fluid is released the gas
pressure will cause a return stroke of the piston.
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Figure 4 also illustrates a stepped piston 35 in the
pressure fluid column to separate the fluid used
through the pump from that in the drill rods 4. This
will enable the former to be a suitable oil while the
latter is watPr. If the bore through tbe backhead 3 and
end of the piston 8 are chromium plated or otherwise
rendered rust resistant water can be used directly in
the hammer assembly 1. This will avoid the necessity
for the second piston 20 illustrated in Figure 2. ~-
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In Fiyura 5 a suitable slidillg valve assembly 36 is
shown. The assembly con~ists of a sliding stepped valve
member 37 movable in a valve casing 38 which is in
communication with the column of pressure ~luid 19.
Inlet and exhaust ports 39 andl 40 are provided for
connection to the delivery of the pressure pump and the
reservoir for pump fluid respectively.
Reciprocation of valve member 37 will enable pump
delivery pressure to be alternately applied to and
relieved from the pressure fluid 19. This in turn will
cause operation of the hammer assembly as described
above.
With this type of valve a relief valve should also be
used when the inlet port is closed. To overcome
unnecessary energy loss an accummulator can be included
in the system. It will be appreciated however that
alternative porting arrangements can be used to avoid
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the necessity for the relief valve.
~ I~ will be understood that the methods of applying thP
intermittent pressure supplied through the pressure
fluid 19 to the piston 8 need not be effected
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hydraulically as set forth in the above example. I may
be applied by mechanic~lly reciprocating a piston to
cause pressure and release of pressure in the fluid 19.
This arrangement could readily be set up by those
skilled in the art and would also preferably include
the relief valve and accumulator re~erred to above.
Also the examples given above describe the use of a
compressible fluid to provide a constant pressure on
the piston to raise it from the bit. Mechanically
resilient means such as compression springs or blocks
of suitable resilient material recessed to extend and
contract into the piston or drill bit may also be used.
Fiyure 6 shows a form of drill rod 4 which can
conveniently be used with this invention.
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The drill rod 4 has an inner pipe 41 which is used as
tha drive rod and provides the passage for the pressure
fluid 19. An outer pipe 42 is welded at 44 to the inner
pipe 41 and this welding can conveniently take place at
the position on the drill rod where flat~ 43 are formed
to enable the rods to be manipulated with spanners.
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/This will
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This will readily be understood by those who make such
drill rods.
It is to be understood that the invention above
described can be widely varied from the specific
examples described and illustrated without departing
from the scope of the invention. The drill rod assembly
and pressure fluid valving can be varied as can the
shape and configuration of the hammer assembly
components. What is essential is that there be
different pressures applied to each side of the hammer
piston.
/CLAIM~:
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