PRESSURE ACCUMULATOR

ACCUMULATEUR HYDRAULIQUE

English Abstract

A multifunction pressure accumulator (21) comprised of a pressure-proof
reservoir having at least two pressure connections (4, 10)
and at least two leak-proof partition walls (2, 5) moving or flexing due to
pressures conveyed to the reservoir and a pressure chamber
formed by means of said partition walls and filled with gas. For filling of
pressure chamber (13) the gas filling channel (14) is taken to the
pressure chamber side at least through one partition wall.

French Abstract

L'invention concerne un accumulateur hydraulique multifonctionnel (21), comprenant un réservoir résistant à la pression pourvu d'au moins deux connexions à pression (4, 10), et d'au moins deux cloisons de séparation étanches (2, 5), ces cloisons pouvant bouger ou fléchir sous la pression transmise audit réservoir. L'accumulateur comprend également une chambre de pression remplie de gaz, formée par lesdites cloisons de séparation. Pour remplir cette chambre de pression (13), un canal à chargement de gaz (14) est amené jusqu'à un côté de ladite chambre de pression, par au moins une des cloisons de séparation.

Claims

6
CLAIMS
1. A multifunction pressure accumulator (21)
comprising: a pressure-proof reservoir having pressure
connections (4,10) at opposite ends thereof; at least two
leak-proof partition walls (2,5) movable along the
reservoir in response to pressures conveyed to the
reservoir; a pressure chamber (13) between said partition
walls for receiving a gas; and a gas filling channel (14)
extending through one of the partition walls (2,5) for
filling of the pressure chamber (13); the gas filling
channel (14) being equipped with a valve, and the
reservoir body being provided with a access hole (16) for
servicing of the accumulator.
2. An accumulator according to claim 1 characterized in
that the reservoir has an end part (7) which includes
separately the access hole (16) and a pressure hole (17).
3. An accumulator according to claim 1 and 2
characterized in that the reservoir includes a reservoir
body (15) and an end part (7) which is detachable from
the reservoir body (15).

Description

CA 02281786 2005-09-08
VVO 98/:'6174 PCT/FI98100140
PRESSURE ACCUMULATOR
The invention relates to a hydraulic accumulator f or hydraulic
systems.
In hydraulic systems used in vehicles, forest machines, sawing
equipment and in a number of other mechanical devices, pres-
sure shocks apperar, due to which components, structures and
pipeworks in the system are subjected to hard stress. Mainly,
these pressure schocks are caused by stroke-like impacts on
hydraulic-driven mechanisms. Since the compression ratio of
hydraulic oils is quite small and neither are there any other
elasticities in the other system, it is advantageous to use a
hydraulic accumulator in the pressure system which, properly
dimensioned, takes all pressure peaks and, functioning this
way, does not allow the pressure to rise too high in the
system, and even the mechnical stress is smaller, so that the
hydraulic systems themselves as well as mechanisms needing a
hydraulic system can be made lighter in using a pressure
accumulator in the hydraulic system.
The major disadvantage in present pressure accumulators is
that several accumulators are needed in the hydraulic system,
whereat the price of the system tends to become too high.
Especially, on using double-acting cylinders and hydraulic
turning gears two accumulators are needed, one for each
direction of motion. The development of double-acting pressure
accumulators has been obstructed by technical problems by
filling the pressure chamber. Especially, the use of mass-
produced ready-machined tubes has been problematic, since in
order to get overpressure gas into place, needed between the
pistons of a double-acting pressure accumulator, it has been a
must to machine and weld the cylinder mantle in spite of the
risk of deformation and, accordingly, problems of tightness.

CA 02281786 2005-09-08
1a
According to the present invention there is a provided a
multifunction pressure accumulator comprising a pressure-
proof reservoir having pressure connections at opposite
ends thereof and at least two leak-proof partition walls
movable along the reservoir in response to pressures
conveyed to the reservoir. A pressure chamber between the
partition walls is filled with a gas and one of the
partition walls has a gas filling channel for refilling of
the pressure chamber, the gas filling channel being
provided with a valve. The reservoir body is provided with
an access hole for servicing of the accumulator.

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WO 98/36174 PCT/FI98/OOI40
2
It can be considered the most important advantage of this
invention that on using an accumulator as per this invention
for a double-acting working cylinder and turning gears only
one instead of two accumulators is needed. Due to this fact t
the system can be purchased at a lower price than before and
less space is needed for one accumulator only, the size of
space it takes is only a half of the previous volume . There
are also less service spots in the system. Further, the weight
of the system is smaller, which is of great importance
especially for the hydraulic systems of lumber trucks thanks
to saved weight and increased load capacity. An advantage of
special significance is that in a pressure accumulator as per
this invention a favourable ready-machined factory-made cylin-
der tube can be used that meets the highest demands and whose
mantle must neither be machined nor welded, whereat the risk
of tube deformation by machining or welding is avoided as well
as the risk of leaks in the pressure accumulator.
In the following the invention is disclosed with reference to
the enclosed drawing.
Fig. 1 is a schematic representation of a double-acting
hydraulic cylinder 20 combined with pressure accumulator 21.
Fig. 2 is pressure accumulator 21 in resting position.
Fig. 3 is pressure accumulator 21 opened for gas fill.
Fig. 4 is pressure accumulator 21 in operating position so
that from the left side of the accumulator illustrated in the
figure working pressure is directed towards the accumulator.
Fig. 5 is pressure accumulator 21 in operating position so
that from the right side of the accumulator illustrated in
the figure working pressure is directed towards the accumu-
lator.
Fig. 6 is pressure accumulator 21 in operating position so
that from both sides of the accumulator illustrated in the
figure working pressure is directed towards the accumulator.

CA 02281786 1999-08-16
WO 98/36174 PCT/FI98/00140
3
Fig. 7 is a pressure accumulator in the end of which there is
a combination of a service and pressure connection.
Fig. 8 is a pressure accumulator in the end of which the
service connection and the pressure connection are separated.
Figure 1 shows a double-acting hydraulic cylinder 20 the
pressure connections 22 and 23 corresponding to its working
motions in two directions. Accordingly, to these connections
the pressure connections 4 and 10 of the double-acting pres-
sure accumulator 21 are connected. When working pressure
enters either of the hydraulic cylinder 20 pressure connect-
ions 22 or 23, the same pressure is directected towards
pressure connections 4 or 10 in the pressure accumulator and
further to pressure chamber 11 or 12 in the pressure accu-
mulator. When there are pressure shocks on either side of the
hydraulic cylinder, the pressure accumulator 21 will take the
shocks absorbing them by yielding due to the spring effect of
the accumulator. The spring effect of the accumulator is
produced in filling the pressure chamber 13 with pressurized
gas.
Figure 2 shows schematically the pressure accumulator 21,
where it has two separate end chambers 11 and 12. The pressure
of the hydraulic system is conveyed to these end chambers from
two different spots in the system. Pressure chamber 13
contains high-pressure gas. Pressure chamber 13 is separated
from end chambers 11 and 12 by pistons 2 and 5 which are
fitted with pressure packings 3 and 6. Piston 5 has a hole 14
running throuhg the piston and joining pressure chamber 13 and
pressure chamber 12 together. Into hole 14 the gas filling
tube 9 and valve 8 are fitted, through which pressure chamber
13 is filled with pressure gas. End part 7 of pressure
accumulator 21 is detachable for filling.
Figure 3 shows schematically the pressure accumulator 21,
where the end part, illustrated in figure 2, has been detached
for refill of pressure chamber 13 with pressurized gas. For
gas refill the gas hose of the filling equipment is connected

CA 02281786 1999-08-16
WO 98/36174 PCT/FI98/00140
4
to filling tube 9. Valve 8 is then opened and a proper
quantity of gas is let in into chamber 13 and then valve 8 is
closed and the end part 7 as per fig. 2 reassembled.
Figure 4 shows schematically the pressure accumulator 21 so
that in a hydraulic system furnished with pressure accumulator
21, pressure prevails in that part of the system which is
connected to end chamber 12 of pressure accumulator 21. Due to
pressure piston 5 has moved towards pressure chamber 13 making
the gas in the pressure chamber to compress and the pressure
to rise further. Due to the spring effect of compressed gas in
pressure chamber 13 the hydraulic fluid pressure variations
will be received in a favourable way so that the impacts of
the shocks get effectively softened and absorbed.
Figure 5 shows schematically the pressure accumulator 21 so
that in a hydraulic system furnished with pressure accumulator
21, pressure prevails in that part of the system which is
connected to the end chamber 11 of pressure accumulator 21.
Due to pressure the piston 2 has moved towards pressure
chamber 13 making the gas in the pressure chamber to compress
and the pressure to rise further. Due to the spring effect of
compressed gas in pressure chamber 13 the hydraulic fluid
pressure variations will be received in a favourable way so
that the impacts of the shocks get effectively softened and
absorbed.
Figure 6 shows schematically the pressure accumulator 21 so
that in any hydraulic system furnished with pressure
accumulator 21, pressure prevails in both the system parts
whhich are connected to end chamber 11, and 12 of pressure
accumulator 21. Due to the pressure piston 2 and piston 5 have
moved towarda pressure chamber 13 making the gas in the
pressure chamber to compress and the pressure to rise further.
Due to the spring effect of compressed gas in pressure chamber
13 the hydraulic fluid pressure variations will be received in
a favourable way so that the impacts of the shocks get
effectively softened and absorbed.

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S
In figure 7 the end part 7 of the illustrated pressure accu-
mulator 21 is furnished with a closing, leak-proof acces hole
16, through which service of the accumulator can be carried
out, its function checked and pressure chamber 13 refilled
without detaching end part 7 and the pressure pipes. End part
7 is fixed to the end of a tubular pressure connection 10 and
the real pressure joint 17 arranged in the side face of this
pressure connection 10.
In figure 8 the closing access hole 16 and the pressure
connection are fixed separately from each other in the end
part 7 of the illustrated pressure accumulator 21.
Especially, it is worth noting that a pressure accumulator
according to this invention can be accomplished as a piston
accumulator as well as a membran accumulator. Instead of the
double-acting accumulator presented in the introductory
chapter, the accumulator can be a multifunction unit. Anyhow,
it is worth noting that the above presentetation of the
invention is made with reference to only one of its
advantageous embodiments. It is by no means meant to confine
the invention to this design only but several modifications
are possible within the inventional concept determined in the
following patent claims.

Representative Drawing