Note: Descriptions are shown in the official language in which they were submitted.
PNæUMATIC P~RCUSSI~B DEVICE
The present inventiDn relates tD the mining tecbnDlDgy,
and more specificall~, it deals with a pneumatic percus-
9 ive dev iC9 .
The present invention may be most advanta~3Dusly used
in pneumatic percussive tD~ls such as pnsumatic mDles de-
si~ned for for~in, bDrehDles in sDil and rDcksc
KnDwn in the art are pneu~atic percussive devices
having valve a~d spDol ~ir distribution arrangements and
pneumatic devices in which air distributiDn is effected
bg the hammer pistDn. All such devices ~re characterized
by the provisiDn of a system Df passages made either in
tbe casin, walls Dr in the bammer pistDn, which are naces-
sary for cDntrDlling DperatiDn D~ the spDDl or valve and
also for supplying cD[npressed air tD wDrking chambers of
the device and for discharging exhaust air from these
chambers. The prDvisiDn of such passages results, on the
Dne hand, in a decrease in the net area of the ha~mer
piston which, in turn, lowers the specific impact power
and, on the Dther hand, complicates the hammer piston
and thus bringing abDut sup~rfluDs stress cDncent-
rators so as to substantially reduce service life of these
parts. This is true to the largest exte~t fDr undergrDund
tools such as pneumatic mDles in which diameter D~ the
casing, h~nce of tha hammer piston, is limited by th0
diameter of the hole, and the impact loads are taken up
nDt only by the hammer piston, but als~ by the casing
~ihich functions as a ,vorking member as well
q.~
Known in the art is a pnsuMatic percussivs device
(D~, C, 1132067) cDmprising a pile hammer lowered intD
a borehole and an independent air distribution ar~an~e-
ment i~stalled Dn the ground level. The pile hammer i5 in
the fDrm Df a trivial impact ~lDrk CDnsisting D~ a tubular
casing clDsed at bDtl ends snd a hammer pistDn mDunted
therein for axial movement. The ham~er piston d~vides the
interior space of the tubular casing into t~lo chambers cDm-
municati~ with each other ~ither thrDugh a throttling pas-
~a~e, or through a passage having a check valve, Dr by
means o~ both. At least Dne of these chambers, which i9
referred to as the cDntrol chamber, communicates thrDu~h
a hose with tbe air distribution arran6emcnt prDvided
Dn the grDund level.
~ he air distribution arrangement is generally in the
fDrm o~ an oscillating system consistin~ Df a spool valve
box and an actuatDr provided tharein and mada in the fDrm
of a spDol Dr a ~lve adapted tD perform Dscillations either
autDmatically or positively under the action Df a drive
mechanism, e.g. a cam drive. ~he self-Dscillating spoDl is
connected by means o~ levers and pivot joints to a pendulum
having an adjustable weighb~
FDr putting the pile hammer in ~peratiDn, the actuator
of the air distributiDn arrangement is autDmatically Dr posi-
tively driven to pe~form Dscillations. During ~scillations
o~ the spoDl the hose connecting the controlled chamber Df
tbe pile hammer tD the air di9tributiDn arr-ngement alter-
nately communicates wlith a coinpr~ssed air source and ~ith
~ 31~
the environment depending Dn pDsition D~ th~ SPDD1~ I,vh~reby
the con~rolled chamber of the pile haramer also alternately
CQmmunicates with the compre~sed air so~ ce and wi.th the
envirDnment. CD nsaquently, pulsating pressure is built up
in the contr~lled chamber. As bDth chambers of the pile
hammer cDmmunicate ~ith each other throu~. the thrDttling
passage Dr through the passaQe incorporati~ a check valve7
rather than thrDu,h a free passaQ~e, pressure in ~hese
chambers is always different. Under the action o~ the pres-
sure difference in the chambers, the harnmer pistDn per-
~orms reciprocations durin~ which it imparts blows either
tD a workin~ implement or to the casin~-in the oppDsite di~
rection. The desired directiDn Df blDWS iS ensured by a pre-
set combination of parameters of the air distributi~n ar-
rangement chosen by way Df eXPerir.1entS.
In certain embodiments of tbe pile hammer tbere are no
passages in the hammer L~)iston and casin, ?ltogether. This
makes the abovedescribed device advantageDus over priDr art
pneumatic percussive devices having a spool or valve air
distributiDn arrangements that cannot be ~mpelemented
without a system of passages which are required fDr control-
linæ the spoDl Dr valve and fDr discharging wasta air from
the chambers and admittinQ compressed air to the chambers.
~ he provision Df a hose connecting the contrDlled
chamber tD the air distribution arrangement which is located
at a substantial distance from the pile hammer reslllts in
an increase in the "dead volume" Df this chamber by th~
amDunt o~ tha volume of the interiDr sp~ce Df the ho,se.
At the s~me bime, an increase in the "dsad volume" of
the chamber is known to result in an 2ddi~ional unproduc-
tive cDnsumption of compxessed air, hence in a lo~er e~-
~iciency9 In addition~ a subistarltial ],engtb of the h~se
limits the rate of pressure pulses ef~ectively transmitted
tD the chamb3r, i.~c limits impact pDwer of tbe pil~ hammer.
In an ideal case~ the rate of pressure pulses ~f~ectively
transmitted through the hose per unit of ti-i~e is deter-
mined by the formula
herein ~3 is the rate o~ pulses:
is the hose length;
~ is the velocity Df sound in the air.
In real life devices, the rate Df effectively trans-
mitted pulses is still lower.
Known in the art is a pneumatic percussive device
(SU~ A, 2613~9), comprisin,, a casin~ and a hammer piston
mDunted in the casing fDr movementr ~he hammer pistDn divi
das the interior space Df the casing into tWD chambers.
A working implement is incorpDrated in the ~rDnt
end part o~ the casing~ A massive balancin~ pistDn is pro-
vided in the rear end part of the casin~ w~~ich is in the
form of a spDol adapted to per~orm sel~- ~scillatDry
movement when compressed air is supplied to th~ device.
A longitudinal passage provideed in the spool permanently
communicates with a controlled chamb~r on Dne side and is
cDmmunicable with e~ther a 90U~C~ of compressed air or
~ 31 ~
the environment on the Dther side dep~nding on position
Df the spoDl. Owing to the fact that the indepandent air
distribution arran~ement is inc3rporated i~ the casing
of the percussive device, there is no need tD use a hose
fDr con~unicatiDn Df the controlled chamber with the air
distributiDn arrangement as was the case in the priDr art
pneumatic percus 9 ive device Df DE,C, 1132067.
When cDmpressed air is supplied tD this device, the
spool providad in the rear end part Df the casinO~ per-
forms self-oscillations v~ith respect to the casingO Depen-
ding Dn pDsition D~ the spDDl during its Dscillatory move-
ment, the controlled chamber alternately cDmmunicates thrDugh
tbe longitudi~al passage Df the spDol with the comprassed
air`source and with the environment~ Therefore7 bhe balan-
cing pistDn which is made in the form of the spool functions
not Dnl~ as a balancing inertia member but also as an in
dependent air distribution device establishin~ communica-
ti~n alternately between the controlled chamber of the de-
vice and the cDmpressed air source and the environment,
Under the acti~n of pulsating prassure in the control-
led chamber and air pressure in the ~ther chamber, the
hammer piston performs raciprocations during which it imparts
blDws tD ~he wDrking implement.
HDwevar, as the balancing pistDn functiDns as a balan-
cing member as wall~ it has suhstantial dimensiDns and mass
as well as the amplitude of DscillatiDns 3D that the size
and mass o~ the device as a whole alsD increasH without
bringing about any increase in bhe impact pDver. Consequently,
ths speci~ic impact power of the device is lo;erGd. ht~
tsmpts mads t-o reduce mass and size oi this ~rior art ds-
vice bv way o~ rGtional choice of dimensiDns, rla~s and
swing Df DSCill~tions Df ths bala~cin$ i~istDn and by lo-
~sring a~plirude Df DSCil1atiOnS D~ the balancing .vistDn
by means OL limitin, abutments failed. ~hus reducin~ r~ ss
of the balancin~ pistDn tD lov7er Iriass Df the device as a
wbole inevitably result in an increase in amplitude Df
its oscil' tio~s so that length D~ bh~ casinæ increasas
and the reduction ~f mass o~ the device as a whDle is nDt
achieved because Df an increase in masS of the casin;;. Re-
ducinæ amplitude D~ D5Ci11atiOnS 0~ the balancin~ pistDn
by r,leans D~ the limitin:; abutlments as is the case in InDwn
pneumatic psrcussive àsvices ~lith valve air distribution
arrangements in which the valve rdmain3 statiD.lar~! alter-
natel~ in one and Dther pDsition is also impossible ~or tWD
reasDns. ~irstly, the balancing pisGDn cannot bs stopped i~
~ne w~ants it to per~Drm its lunctiDn. ~ecDndly, this
pistDn being a sel~-oscillatinO member, it cannot remain
stationary a~ter its engaga~ant ~,iththe abutment since the
very principle DL? its selL?-DscillatiDn mDvement involves
the development Df a rebound ~orce under the action D~ which
tha balancing piston is instantly reversed after its st~p-
pa~e. As a result, ~requency o~ oscillatory mDvement o~ the
balancing piston is only determined b~ a very short tims
o~ its shift between the tWD abutments and it will become
tDo high SD as to rule out normal DperatiDn o~ the device.
~4~
--7--
It is an object of` the invention to sub3tantially
reduce mass and size of the device as a wbole while re-
taining advantages of pneumatic percussive devices havin~
a sirlgle controlled chamber and cDmparatively high impact
power.
~ hes~ and Dther ob~cts ar3 accomplished by that in
a pneu~atic percussive device having a casing accDmmodating
a movable hammer piston dividing the interiDr space Df
the casing into tWD chambers, the first chamber bein~ de-
fined by th~ casing walls and the hammer piston and the
second chamber being defined by the hammer pist~n an~ an
air distribution arrangement accDmmodated in the casi ~
and having a movable actuator member dividing the interior
space o~ the air distributiDn arran~eLIent into at least
two cavities, the pressure in the first cavity ensuring
mDvement of tha actuator member to ons of its limit posi-
tions, the second cavity permanently communicating with the
secDnd chamber and alternately communicatin~ with a cD~npres
sed air source and the environment, accDrding to the in-
ventiDn, the first cavity of the air distribution arrange-
ment communicates with the second chamber via a throttling
passage.
The provision of the throttling passage establishing
communicatiDn between said secDnd chamber and first cavity
prevents an instantaneous develo~ment of a forcs that
cbanges direction of movement o~ the actuator member a~ter
its stoppage in Dne of its limit positions~ Durin~ its
self-oscillatDry movement between the two abutm~nts, the
3(,~ 3
-'-
3ctuatDr member can thus stop in each Df its limit p~8i-
tiDn3, the stDppaJ,e time in Dne pDsitiDn bein~ equal to the
time fDr filling said first cavity D~ the air distributiDn
arrangement with air through the throttlin, pas~age and
the stDppage time in tbe other positiDn being equ~l tD
the ti~lla for discharging cDmpressed air thr~ugh this pas-
sage frDm said first cavity. ~he law of oscilla~Dry mDve-
ment of the actuator member in this case is determined by
parameters Df the thrDttling passage and said ~irst cavity
Df the air distribution arrangement, but it dDes nDt sub-
stantially depend Dn its inertia properties. As a result,
an actuatDr member may be used the size and amplitude Df
Dscillations Df which can be reduced to the values suffi-
cient not only fDr enabling ~ree admissiDn and discharge
Df air. In comparison with the davice disclDsed in SU, A,
261319, size and mass of this device ~re reduced as a
whDle withDut a reduction in its impact p~wer SD that the
specific impact power, i.eO the impact pDwer-tD-~mass Dr
volume ratiD Df the device increases.
It is preferred that tha first cavity ~f the air dist-
ribution arrangement and the second chamber o~ the casing
cDmmunicate with each Dther through at least Dne au~iliary
thrDttling passage, the Dutlet opening Df which Dn the
side Df the first cavity Df the air distribution arrange-
ment is provided with a check valve secured to a wall of
the air distribùti~n arrangement.
This facility allows a~ Dptimum time for admis~i~n Df
cDmpressed air to said 3econd chamber to be chDsen wibh
--9~
a preset tim~ for exhaust of w~ste air thare~rDm,
~ o prDvlde ~Dr the pDssibility o~ choice of an optim~m
ti~a fDr dischax~e Df compre~3ed air ~ro~ sa1d second cham~
ber with a prese~ tim~ for air ~dmis~ion the~stD~ it i~
pre~srred that the interior space o~ the air distribution
arrangement and the ~econd cha~ber o:e the casin~; communica-
te with e~ch other ~hrcu~h at le~st Dne 3~xiliary thrDttling
passage haviog ~n outlet Dpeni~g therso~ on the side o~ th~
second chambar o~ the casin~ provided with a check valv0
sacured tD a wall Df the air distribution arra~gement.
~ o prevent uncontrDlled air over~lDws ~r~m the ~ir
line i~to tha ~irsb cavi~y D~ the air distribubion arrange-
ment, it i5 pre~erred, D~ the cDntrary, that ~ di~phra~m
be prD~ided on the surface o~ the actuatDr member acted
upo~ by cDmpr~ssed air pressure in said ~irst cavity, bhe
diaphragm being secured to the periphery o~ the air distri~
bution casing.
The invention will nDw be described with r~erence to
a specific embod$ment illustrated i~ the accompan~ing dra-
wings, in which:
Figure 1 is a ganeral view o~ a pneumatic percussive
device according tD the invention;
~ igure 2 i~ an embodiment of an air distributio~ ar-
rangeme~ having its actuator member which is in a position
allowing compressed air t~ be admitted tc o~e o~ chambers D~
~he device;
Figura 3 i~ ditto of Figure 2 showing a positiou o~ the
3~
~10-
actuator me~ber allswing waste air tD be exhausted from
said chsmber o~ the device;
~ i~ure 4 ie an embodiment o~ an air distribubion ar-
rangement U5i~g a spring, shown in a position allowin~
~ompressed air to be admitted to one of chamber~ of the
device;
Figure 5 is ditto of Figure 4, but shDwing the actuatDr
member in a position allowing waste air to be e~hausted
from said chamber D~ the device;
Figure 6 is an embodiment of an air distributiDn ar-
rangement having two throttling passages allowin~ compres-
sed air to be admitted to one chamber D~ the ~evice only;
Fiæure 7 is an embodiment Df an air distribution ar-
ran~ement having tWD thrDttling passag~s allowing cDmp-
ressed air to be admitted only to the interiDr space of
the air distribution arrangement;
Figure 8 is an embodiment of an air distributiDn ar-
ran~ement usin~ a diaphragm.
A pneumatic percussive device comprises a casing 1
(Figure 1), e.g. of a tubular shape.
A working implement 2 is abtached to Dne end face
of the casing, and an air distribution arrangement 3 vvith an
air supply hose 4 is provided at the other end of the ca-
sing. A hammer piston 5 is mounted for axial movement in
the casing 1. ~he hammer piston 5 dividea the i~ erior
space of the casing into two chambers 6, 7. The first
chamber 6 i5 defined by the walls o~ the casing 1, the
hammer piston 5 and the workin~ implement 2. ~he second
chamber 7 is defined by the ~115 of the c~5ing 1~ hammor
~3~
pistDn 5 and th~ air distribution ar~angament 3~ The f'irst
and second chambers 69 7 communicate with sach otber bg
any apprDpriate known means (not s~own), limiting overf~Dws
of air f`rom the second chamber 7 tD the first cbamber 6.
A known means Li~iting overf'lDws of air betwec~ the first
and secDnd cha~bers 6 and 7 may be in the form of a t~.rot-
tling passa~e v~hich ma~ be in the ~orm Df an annular space
between the hammer pist~n 5 a~d the casing 1 or in the
form o-f a passage incDrporating a check valve, or bDth~
~ he air distribution arrangerrlent 3 has a movable ac-
tuator me~b~r 8 (Figu~e 2) dividing the interiDr space o*
a casing 9 of the air distribution arrangement 3 intD at
least two cavities~ and in this particular case, intD three
cavities 10, 11, 12 since the actuator member 8 i9 made
in the form o~ a stepped spDol mDunted coaxially with the
hammer piston 5 (f'iOure 1) in the casing 9 (Fi~ure 2) of
the air distribution arrangement 3 f'or r~cipr DC ati D ns bet-
ween abutments.13 and 14 provided in the casing 9 of the
air distribution.arrangement 3. ~he f`irst cavity 10 i~
de~ined by the walls of the casing 9 of the air distribu-
tion arrangement 3 and an end f'ace 15 of' the actuator mem-
ber 8. Pressure in the first cavity 10 ensures a shift of
the actuator me~ber 8 t~ one of its limit positions~ ~he
secDnd cavity 11 is d0fined by the walls of the casing 9
and annular end ~aces 16 and 17. ~he second cavity 11
permanently communicates thrDugh communicating radial
and lDngitudinal passages 18 and 19, respectively, with
the second chamber 7 of the device. The acbuatDr member 8
ha~ a cavity 20 i~ the form of a ~leevc having a bottom 21.
3~L
-12-
The cavity cDrnmunicatos, via a passage 22, with ~ha
air supply hose 4 and, via a radial passa~e 239 with
the seeDnd eavity 11, and the seeond cavity 11~ d0pending
Dn pDsition of the aCtUatDr member 8 alt~rnatel~ c~mmu-
nicates witb tbe air sup,)ly line when in Dne positiDn, via
the radial passage 23, and, via th0 radial passage 14, with
the envirDnment when the actuator memb3r ~ is in the other
p~sition (Fi~ure 3). The third cavit~ 12 defined by an end
faee 25 and the walls of th~ easing 9 Df the air distribu-
tion deviee permanently eDmmunicates with the enVirDnment
via a radial passa~e 26 (Fi~ure 2)~ ~be first cavity 10
permanently communicates with the seeond chambar ? via 3
throttling passage 27 and functions as a reeeiver.
Fi~ures 4, 5 show an emb~diment ~f a casin~ 28 Df
the air distribution arrangemsnt 3 and an actuatDr membsr 29
of anDther type in which th3re is nD cavitg in ths form Df
a slseve inside the acbuator member 29, In this case a
first cavity 30defined by the ;ialls of the casin~, 2~ and
an end faee 31 Df the actuator membsr 29, direetly com-
munieates, via a thrDttling passage 229 with the seeDnd
ehamber 7 of the device and funetions as a reeeive~0 A
seeond cavity 33 defined by a wall ~ the easing 2~ and
annular end faees 34 and 35 permanentl~ comr.unicates with
tbe seeond ehamber 7 through CDmmUniCatin~ radial and
lDn~itudinal passa~0s ,~ and ,7, respeetively. Dependin~
Dn pDsitiDn Df ~he aetuator member 29, tbe seeond eavity 33
may eDmmunicate eithsr with the snvirDnrnent tbrough a radial
--13-
passage 38 ~n tbe pDsitiD~ shDwn in ~igurs 4) Dr with the
interior of the air suppl.y hose 4 thrDu~h pas.ia~es 39 and
22 (in the position of ~he actua~or m~mbe~ 29 shown
in Figure 5). ~ third cavity 40 defined b~ the ~alls
Df the casing 28 and an end face 41 of the aC~UatDr mem-
ber 29 permarently CDmmunicates~ via the pas~a~3 22, with
the air supply hose 4. A spring 42 is prDvided in the
first cavity 30 batween the wall Df the casing 28 a~d
tha end face 31 of the actuator member 29, the force of
the spring placing the actuatDr member 29 in the pDsitiDn
shown in ~igure 4 in which the second chamber 7 cDmmu-
nicates with the environment.
To allow fDr a choice Df an optimum ~ime for e~;haust
Df co~pressed alr from the second chamber 7 with a preset
time for air admission theretD, the first cavity 1 ~Figure 6)
cDmmunicates with khe secDnd chamber 7 through an auxiliary
thrDttling passage 43. '~he outlek opening ol the throttlin~
passage Dn the`side of the secDnd chambar incDrporates
a check valve 44 secured tD the wall Df the casing 9 of
the air distribution arrangement 3 fDr allowin~ air to pass
t D the secDnd chamber 7 only.
If it is desired tD make choice of an Dptimum time fDr
cDmpressed air admission tD the sacDnd chamber 7 with a
preset time for e~baust Df waste air therefrom.9 the outlet
Dpening of the auxiliary tbrottling passage 43 incDrporates
Dn the side Df the first cavity 1 a check valve 45 secured
tD ~he wall D~ the casin~ 9 of tho ai.r distributiDn ar~
rangement 3 which allDws compressed air to be Dnly admitted
tD the fir~t cavity 10.
J~
_ '1 L~~
Fi~ure 8 shDws an embDdiment D~ the air dlsbributiDn
arrang~ment 3 similar to that described with re~erenc~
tD F~gure 19 but having a diffsrent structural form D~ an
actuator member 460 This actuator member 46 has an en~
~ace defining a first cavity 47 in the fDrm o~ a ~le~ible
diaphragm 48 secured to the periphery vf the casing 9 Df
ths air distributiDn arrangement 30
~ he pneumatic percussive d0vice accDrding tD the in-
ventiDn functions in the ~ollowing manner.
When compressed air is ~ed to the device accordi~g
tD the inventiDn through the air supply hDse 4 (~igure 2)
from a compressed air source (not shDwn), the actuator mem-
ber 8 in the fDrm Df a stepped spoDl moves under the ac-
tion of cDmpressed air pressure upon tbe bDttom 21 of th3
sleeve 24 until it e~gages ~Jith the abutment 13, i.e. until
it is in a positiDn in which compressed air sup~lied through
the hose 4 ~ills the secDnd chamber 7 of bhe casin~ 1
thrDugh the,passage 22, the caviby 20, the radial passage 23
of the acbuatDr member 8, the second cavit~ 11, the radial
and longitudinal passages 1~ and 19 of the casing 9 D~ the
air distribubion arran~emant 3. Whe~ compressed air is ad-
mitted tD the second chamber 7, an additiDnal force applied
Dn the part of the secDnd csvity 11 to the end face 16
acts upon the actuator member 8 to press ti'e ~ctuator mem-
bsr 8 against the abutment 13.
At the same time, prsssure in the first cavity 10
increases gradually si~ce its chargin~ with compressed air
3~
-15-
DCCU~S thrD ugh tbe tbr~tling passa~;~ 27 cDnn~ctin~ this
~irst cavity ~unctioning as a receiv~r to the sacond
chamber 7. Admis~iDn of cDmpressed air to the secDnd
chamber 7 lasts until air pressure in the ~irst cavity 10
reaches duri~g its filling a value which is su~Picient to
shi~t the actuator membar 8 to the Dth~r pDsitiDn9 iOe.
until its en~a~ement witb the abutme~t 14 as shown in
Figure 3.
In the ~ew positio~ o~ the actu~tor member 8~ admis-
~iDn D~ c~mp~esse~ air tD the second chamber 7 is stopped
as the radial passage 23 is shut-off, and wsste air i~
exhau~ted , i.e. in this position o~ the actuat~r member 8
the secDnd chamber 7 cD~municates with the envirDn~ent via
the lo~itudinal and radial passages 19 and 18 Df tha
casing 9 o~ the air distribution arran6ement 3, it9 sec~nd
cavit~ 11 and radial pass~ge 24. During air exhaust~ air
pressure in the second chambar 7 abrupbly decre~ses, but
pressure in bhe ~irst cavit~ 10 decre~ses gradually since
its dischar~e OCCUr9 through the thrDttLing passa~e 27.
~he acbuator membsr 8 remains in this position until pres-
sure in the ~irst cavity 10 decreases tD a value ~t whicb the
force o~ pressurs acting upon the end ~ace 15 D~ the ac-
tuator member 8 becDmes lDwer tha~ tha force D~ the ~ir
line pressure in the cavity Z0 actin~ upDn the botbom 21.
Then the abDvedescribsd process Df the sclf-~scillati
moveme~t of ~he actuator membar 8 with stoppages at bwD
limit positio~9 is regularly repeated.
-16-
Dependin~ on position ln which the actuator mem~
ber 8 is lDcated, tbe second cbamber 7 cDmm~nicate.s either
witb ~ ~surce 9~ c~mpressed a ~ and i9 ineul~tad ~r~m the
environment3 sr with t~ envirDn~ent and is insulat~d ~rom
the sDurc~ Df cDmpr~ssed air. ~hsrefora, puls~ting pres-
surs devalDps in the secDnd chamber 7 of the device when
compresssd air is supplied thrDugh the air supply hDse 4~
As the first chamber 6 (Figure 1) and the 3econd chamber 7
commun~cate through any appr~priate kaown maans (nDt shown)
restricting air passage from one chamber 7 (6) tD ansther
rather than through an unobstructed passage, pressure
in the ~irst and second chambers 6, 7 is differ~nt~ Under
the action o~ the pressure dif~erence between the chambers
6, 7 Df the device, the hammer piston 5 per~Drms reciproca-
tiDns in the casing 1. One can chD~se such a c~mbinatiDn
Df parameters of the air distributiDn arrangement 3 by w~y
D~ expsriments that the ha~mer piston 5 will impart blows tD
the workinO implemenb 2 during reciprocations in bhe ca-
sing 1 every cycle o~ operatiDn of tha air di~tributi~n
arrangement 3.
OperatiDn ~f the air distributiDn arrangement 3 bhe
amb~diment Df which i3 sh~wn in Figures 4, 5 is identical
to ~peratiDn of the air distributiDn arrangement 3 shown in
Fi~ures 2, 3 as regards functions.
When cDmpressed air i9 admitted tD the device, thrDugh
the air supply hDse 4 ~Fi~ure 4), the actuator member 29
is moved under the actiDn o~ air pr0ssure up~n tha end
face 41 thereof in a positio~ (Figur~ 5) in which bbe
secDnd chamber 7 of the ca9ing 1 communicates, via the pas-
~t~ ~ 3l4
-17-
sages 37, 36, 39 and 22, with a cDmpre:ised air sDurce SD
that ccmpre~sed air is admitted to the second chamber 7.
During admissiDn of compressed air, an additiDnal ~orce
eDunteracting the force o~ the spring 42 and caused by
pressure acting upon the end face 34 acts upon the act~atDr
member 29. ~he admission lasts until pres~ure i~ the first
eavity 30 during its filling with compressed ~ir through
the throttling passa~e 32 reaches a value which is suflicient
for shifting the actuator member 29 to a positiDn in which
the secDnd chambsr 7 (Figure 4) communicates, via the pas-
sagas 37, 36 and 38, with the environment. In tbis positiDn
of the actuator member 29 waste air is exhausted frcm the
seeond chamb~r 7. Simulatneously with the exhaust, bhe first
cavity 30 functioning as a receiver is discharg~3d through
the throttling pessage 32 so that the actuator member 29
is again shifted to a position allowing cDrl~)ressed air
tD be admitted tD the second chambar 7~ ~he abovedescribed
process is then repeated~ Operation of the device as a
whole is 9imilar to Dperation of the ~evice with the air
disbribution arrangement described 1;/ith reference to Fi-
gures 2, 3.
Oparation of bbe device accordin~ to the invention
using the air distributivn arranrement 3 having an au~iliary
throttling passage 43 (Figure 7 ) .1lith an Dutlet opening
thereof incorporating bhe check valve 45 differs from that
described above only in the fact that ch~rging o~ the ~irst
cavity 10 is effeet~d through th~ throtbling passage 27 and
~8~ ~ ~
-18-
the auxiliary throttlin~ pas,sa~,e 43 and discharg~ is
e~fected thrDu~h the throttling passage 27 Dnly.
If the outlet openin~ of tha au~iliary throttli~
passag3 43 is prDvided with the check valve 44 (Figure 6),
the first cavity 10 is discharged through the throttlinO
passage 27 and tha auxiliary throttling passage 43.
OperatiDn of the device using the air distribution
arrangement 3 with the diap~ragm 48 (Figure 8) is similar
to operatiDn D~ the devica described with re~erence tD
~igures 2, 3. The di.fferenc~ rasid~s in that the diaphragm
~8 functions aa ~he end face de-~ining the first cavity 47
comr.1unicating with the secDnd chamber 7 thrDugh the thrott-
ling passage 47.
~ he number Df embodiments of the actuator member 8
and air distributiDn arrangement 3 is nDt li.~ited to the
two er.bodiments shDwn in Figures 2, 3 and -~75.~ir distri-
bution arran-.,ements havinO different designs o~ the actuator
member can ba used~ ~cwever, with any embodim~nt thareDf,
it is necessar~ that there shall be at least one throttling
passa~3 e_tablis,.ing cDmmunication between a chamber D~
the casing alternately communicatinO with a cDm~pressad
air source and the environment with a cavit~ Df the air
distributiDn arr'angement the pressure in which ensures move-
ment o~ the actuator member to one of its limit positionsO
In comparison with the prior ~,rt, the pneumatic per-
cussive device accordin~ to the invention has an air distri-
bution arrangement D~ minimum mass and si~e. ~his makes
it possible tD lower size and mas~ ~f the device as a whole
WithDUt cDmpr~misin~ its ir~pac~ po-i~er ~/hila r~taininb
all advantag~s D~ pneumatie percussiv~ devices havin~ a
single eontrDlled ehamb3r~ A~ a r~sult, th~ spscifie
ir.ipaet pDwer, i.e~ the power-tD-mass Dr volume ratiD Df
the deviee increases. On the other hand, if mass and size
Df the d~vie~ according tD t'ne inventiDn remain the same
as befDrs, absDluta i:..pact power Df th~ devics inereases
b~ virtue Df an increase in its specific pow~r which,
in ths snd Df the day, results in an increase in prDduc-
tivity in applicatiDns cf this devieeO
1'1
