Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1 33112 ~ ~
An arrangement for operating hydraulic actuating means
in a rock drilling boom and the like boom construction
The invention relates to an arrang~ment for
operating hydraulic actuating means provided with
overcenter valves in a rock drilling boom and the like
boom construction, the overcenter valves being con-
nected to pressure fluid conduits of the actuating
means and to control conduits for the valves in such a
manner that the valves stop the flow of the pressure
fluid in the conduits in a direction away from the ac-
tuating means when no pressure fluid is supplied to
the actuating means, and when pressure fluid is
supplied to one of the conduits, the overcenter valve
connected to the other conduit opens when the pressure
of the supplied pressure fluid acts on its control
conduit, allowing the flow of the pressure fluid
therethrough away from the actuating means, the
arrangement further comprising hoses for pressure
fluid extending from the carrier of a rock drilling
apparatus in the longitudinal direction of the boom
for supplying pressure fluLd to the actuating means in
the boom and for removing it therefrom, and regulating
valves for controlling each one of the actuating means
Hydraulic actuating means, ~uch as cylinders
and hydraulic motors, are used widely in a rock drill~
ing equipment. Prior art actuating means are operated
by means of two robust hoses for pressure fluid. The
pressure fluid is introduced into the different cham-
bers of each one of the actuating means by means of
control or regulating valves placed in front of the
operator. As a result, as the boom of a rock drilling
machine may comprise eight or even more cylinders or
actuating means, the number of requisite hoses is
usually two times that of the actuating means. With
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high-pressure hydraulics, such a large bunch of hoses
is very heavy. The hoses extend from the carrier to
the boom and are liable to damage during operation.
The construction of the equipment cannot be optimized
due to the fact that the space requirement of the
bunch of hoses always has to be taken into account as
well as the movements and weight of the hoses.
Another problem presented by the long hoses and
the control of the actuating means with valves placed
next to the operator is that the cylinders as well as
other actuating means usually comprise a so called
overcenter valve the function of which is to prevent
the boom, e.g., from falling down in case of hose dam-
age or when the pressure of khe pressure fluid drops
abruptly for some other reason. In order that the
overcenter valve could operate properly, its control
conduits have to be depressurized, which takes place
through a long hose and a regulating valve into a
pressure fluid tank. This makes the operation of the
valve slow and le~s effective. The overcenter valve
also often performs a load limiting function which
suffers from the long hose and is inoperative in known
solutions when pressure fluid is being introduced into
the actuating means.
The object of the invention is to provide an
arrangement for operating hydraulic actuating means in
a rock drilling boom, which avoids the above drawbacks
and is simple and easy to realize both in existing and
new apparatuse~. This is achieved according to the in~
vention is such a manner that the arrangement com-
prises for the supply of pressure fluid to the actuat-
ing means a supply hose common to at least two actu-
ating means and extending longitudinally of the boom,
and a common return hose for removing pressure fluid
from the actuating means, respectively, both hoses
.
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being branched at suitable points for connection to
each one of the actuating mean3; that at the most two
remote-controlled, cartridge-type valves connected to
each one of the actuating means are used as regulating
valves in each one of the actuating means connected to
the same pressure fluid supply hose; that the regulat-
ing valves in each one of the actuating means are con-
nected between the pressure fluid conduits of the ac-
tuating means and the pressure fluid supply hose; that
the overcenter valves are connected between the press-
ure fluid conduits of the actuating means and the
pressure fluid return hose; and that the control con-
duit of both overcenter valves is arranged to obtain
control pressure when the regulating valve connected
to the same pressure fluid conduit of the actuating
means as the other overcenter valve passes pressure
fluid into said conduit.
The basic idea of the invention is that the
regulating valve(s) of each one of the actuating means
i~(are) remote-controlled cartridge-type valves mount-
ed fixedly in the actuating means or in a block inte-
gral with the actuating means. The regulating valves
are connected between the pres6ure fluid supply hose
and the pressure fluid conduits of the actuating mean~i
while the overcenter valves are connected between the
pressure fluid conduits of the actuating means and the
pressure fluid return hose. By controlling the regu-
lating valves, e.g., electrically, by means of high-
pressure or low-pressure pressure fluid, pressurized
air or in some other way, the actuating mean~ can be
operated in a desired direction by applying pressure
fluid into the desired pressure fluid conduit of the
actuating means, while a required amount of pressure
fluid is discharged from another pressure fluid con-
duit of the actuating means by the respective over-
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~.;. s~
center valve in response to the pressure of the pres-
sure fluid applied through the regulating valves. In
the arrangement according to the invention, all hy-
draulically operated actuating means required in the
boom, for instance, can be operated by means of a
single pressure fluid supply hose for introducing
pressure fluid into the boom, and a single return hose
for returning the pressure fluid into the pressure
fluid tank. A distributor ic provided at the upper end
of the boom, whereby a short pressure hose and return
hose can be branched from the distributor for each one
of the actuating means. The control of the actuating
means does not additionally require but a light bunch
of electric conductors, for instance, which is easy to
pass along the boom in such a manner that it is not
liable to damage and without any special construction
of the boom.
The invention will be described in more detail
in the attached drawings, wherein
Figure 1 is a schematical view of one embodi~
ment of the invention;
Figure 2 is a schematical view of another embo-
diment of the invention; and
Figure 3 is a schematical cross-sectional view
of a valve assembly suitable for the realization of
the arrangement according to the invention.
Figure 1 shows a hydraulic cylinder 1 acting as
an actuating means. A piston 2 disposed within the
hydraulic cylinder divides the inner space of the cyl-
inder into two separate chamber~ 3 and 4 for pressure
fluid. A conduit 5 for pressure fluid is connected to
the chamber 3, and a conduit 6 for pressure fluid to
the chamber 4, respectively. A pressure-controlled
overcenter and overload valve 7 is connected to the
pressure fluid conduit 5, and a similar valve 8 is
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connected to the conduit 6. At the other side, the
valves 7 and 8 are connected to a return hose 9 for
returning pressure fluid into a tank 10. Non-return
valves 11 and 12 are connected in parallel with the
valves 7 and 8. The operation of the non-return valves
will be described more closely below. The figure
further shows a pressure fluid supply hoæe 13 which is
connected to controllable valves 14 and 15. ~he valve
14, in turn, is connected through a non-return valve
16 to the conduit 5, and the valve 15 is at the other
~ide connected to the conduit 6 through a non-return
valve 17. A control conduit 18 for the valve 7 con-
nected to the conduit 5 is connected to that side of
the valve 15 which faces the conduit 6, and a control
conduit 19 for the valve 8 correspondingly to that
side of the valve 14 which faces the conduit 5. The
valve 7 further comprises an overload control conduit
20 extending from it to the conduit 5, and the valve 8
comprises an overload control conduit 21 extending
from it to the conduit 6. Control signal lines 22 and
23 are connected to the controllable valves 14 and 15,
respectively. The broken line 24 indicates schema-
tically that the entire assembly of Figure 1 is fitted
substantially integrally with the body of the cylinder
1 so that only the pressure fluid hose 13 and the re- ~ 1.7
turn hose 9 and the control signal lines 22 and 23 are
attached to the cylinder.
With the connection of Figure 1 and in the
position of the control valves 14 and 15, the fluid
pressures are equal in the chambers 3 and 4, whereby -~
the piston 2 has assumed a determined positioned with
respect to the cylinder 1. Under normal conditions,
the fluid contained in the chambers 3 and 4 is not
able to escape through the conduits 5 and 6, because
the pressure-controlled valves 7 and 8 on one hand
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and the non-return valves 11, 12, 16, 17 on the other
hand prevent the flow of the fluid, and the cylinder
i8 thereby locked in position. Correspondingly, when
the valves 14 and 15 are in the position shown in the
figure, the pressure in the pressure fluid supply hose
13 is not able to advance due to the non-return valves
disposed internally in the valves, and the pressure of
the fluid is not able to act on either one of the val-
ves 7 or 8. Nor is the fluid able to flow into the
conduits 5 and 6 in the downstream direction of the
non-return valves 16 and 17. When the valve 14 is con-
trolled by means of a control signal applied through
the signal cable 22 80 that it i~ displaced to a
position in which the pressure fluid from the pressure
fluid hose 13 is able to flow straight therethrough,
the pressure fluid enters the conduit 5 through the
non-return valve 16 and passes further into the cham-
ber 3 while the pressure prevailing in the control
conduit l9 opens the pressure-controlled valve 8, al-
lowing the flow of pressure fluid from the chamber 4
through the conduit 6 via the valve 8 into the return
hose 9. When the control signal to the valve 14 is cut
off, the valve returns to the position shown in the
figure, and the control pressure in the control con-
duit 19 i8 released through small leakages of the
valves, whereby the valve 8 is closed and the piston 2
is again locked in position. The operation is fully
identical in cases where the valve 15 is controlled
similarly as the valve 14 except that the piston 2
moves in the opposite direction. An overload situ-
ation, e.g., when an excessive pressure prevails in
the chamber 3, causes the valve 7 to be opened
through the conduit 5 and the overload conduit 20 so
that pressure fluid enters through the valve 7 into
the return hose. When the piston is displaced, fluid
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from the return hose enters the conduit 6 through the
non-return valve 12 and passes further into the cham-
ber 4 of the cylinder 1, thus allowing the piston to
move until the overload is compensated for. If the
pressure in the conduits 18 and 19 cannot drop due to
the fact that the valves 7, 8, 14 and 15 do not allow
any leakages, the pressure from the conduits 18 and 19
has to be led into the return hose through a separate
passage e.g. through a conduit provided with a
throttle. The pressure drop can be similarly effected
in such a manner that the valve~ 14 and 15 are e.g.
three-way valves which at the re~t state connect the
auxiliary conduits attached to the conduits 18 and 19
to the return hose 9.
The operation and structure of the valves 7 and
8 and the valves 11 and 12 are generally known, and
the valves are standard fittings in hydraulic cyl-
inders, being usually of the cartridge type and formed
either in the body of the cylinder or fastened as a
separate valve assembly at the end of the cylinder.
According to the invention, the control valves pre-
viously positioned at the end of long pressure hoses
beside the operator are replaced with the cartridge
type control valves 14 and 15 mounted fixedly to the
cylinder in the form of and integral assembly and with
the non-return valves 16 and 17 likewise forming an
integral assembly therewith. The entire valve assembly
is thereby mounted as an integral part of the cylinder
or the like actuating means, and the actuating means
can be controlled simply by means of an electric sig-
nal or other similar control signal applied to the
valves 14 and 15. A single pressure fluid hose and a
sir,gle return hose are required for the operation of
all the actuating means and cylinders positioned at
the end of the boom of the rock drilling machine, for
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instance. The hoses are branched from one actuating
means to another at the end of the boom. In this way,
no large bunches of hoses are formed because the
valves required for the control of the entire actu~
ating means are attached to each particular actuating
means and the control is effected by means of thin
electric conductors, a thin pneumatic hose or the
like.
The solution shown in Figure 2 corresponds to
that of Figure 1 except that a ~o called proportional
valve 25 is used in the case of Figure 2 in place of
the two separate ON/OFF type valves of Figure 1. In
the proportional valve, the flow amount of the press-
ure fluid can be adjusted continuously in such a man-
ner that the fluid flows to either conduit or to
neither one of them. The valve 25 is controlled by
means of a control signal 26. When no control signal
is applied, the valve is in the position of Figure 2,
whereby the flow of the pressure fluid into the cyl-
inder is completely prevented. When the control signal
is connected, it displaces the spindle of the valve to
the left in Figure 2 so that each one of the conduits
still does not allow the flow of the pressure fluid.
By ad~usting the intensity of the control signal, the
spindle of the valve 25 is di~placed farther to the
left or back to the right, whereby pressure fluid is
able to enter either one of the conduits, respective-
ly.
Figure 3 is a schematical cross-sectional view
of a valve assembly with two cartridge-type valves
suitable for realizing the invention. It comprises
cartridge-type overcenter valves 7 and 8 mounted in
borings formed in the body of the actuating means 1.
The overcenter valves comprise non-return valves 11
and 12, respectively, connected in parallel therewith.
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The structure and manufacture of such overcenter
valves as well as the mounting of then in the body of
the actuating means and the formation of the requisite
conduits are known per se and quite obvious to one
skilled in the art, wherefore they are not described
more precisely herein. Cartridge-type regulating
valves 14 and 15 are further mounted in the borings
formed in the body of the actuating means 1, which
valves are provided with solenoids 28 and 29, respec~
tively, for electric control. The overcenter valves 7
and 8 are connected by means of conduits not shown to
the pressure fluid conduits of the actuating means 1
and to the return hose 9 for the pressure fluid. The
regulating valves 14 and 15, in turn, are connected by
means of conduits not shown to the pressure fluid con-
duits 5 and 6 of the actuating means 1 and to the
supply hose 9 of the pressure fluid, respectively.
Conduits 18 and 19 extend from the overcenter valves 7
and 8 to the regulating valves 15 and 14 and non-re-
turn valves 17 and 16 are provided between the con-
duits 18 and 19 and 6 and 5, respectively. The struc-
ture of the valves and the connection and manufacture
of the conduits are known per se and will not be de-
scribed more closely herein.
The invention has been described above only
schematically, and only a few practical embodiments
have been presented. However, the invention can be
realized in various ways and with various connections,
depending on the requirements in each particular case
and the desired mode of operation. In place of the
ON/OFF type valves 14 and 15 of Figure 1, for in-
stance, it is possible to use two individual propor-
tionally operating valves. In the embodiment of the
invention, it is essential that the valves required
for the control of the entire cylinder or actuating
: ::-'~,--:
lo 1 3 3 1 1 2 6
. . ,
means are cartridge-type valves mounted in valve hous~
ings formed fixedly in the body of the cylinder or the
actuating means, or in a separate valve block mounted
integrally with the body of the actuating means or ~he
cylinder. The apparatus is thereby controlled electri-
cally or in some other remote-controlled manner, and
pressure fluid can be supplied to several actuating
means through a single primary supply hose and re-
turned to the tank through a single primary return
hose. In certain cases, it is possible to use a
pressure-controlled non-return valve in place of the
overcenter valve.
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