Note: Descriptions are shown in the official language in which they were submitted.
I
HYDRAULIC DAMPING SYSTEM AND ARTICULATED VEHICLE HAVING SUCH
A DAMPING SYSTEM
The invention relates to a hydraulic damping system for damping pivoting
movements
of two vehicle parts connected to each other at least indirectly via a pivot
joint, with at
least one damper configured as a double-acting hydraulic cylinder, the
pressure and
suction pressure chambers of which are connected to each other via a
proportional
pressure relief valve.
Furthermore, the invention relates to an articulated vehicle, in which two
vehicle parts
are pivotally connected to each other at least indirectly via a pivot joint
and are
brought together by means of at least one double-acting hydraulic cylinder of
a
damping system, wherein a proportional pressure relief valve is arranged in a
damping line connecting pressure and suction pressure chambers of the at least
one
hydraulic cylinder.
Articulated vehicles are motor vehicles, which are preferably configured as
low-floor
articulated buses, wherein these have a front vehicle part and a rear vehicle
part as
seen in the direction of travel. A turntable-like hinge arrangement is
provided
between these, the arrangement allowing the reduction of the turning radius of
the
corresponding motor vehicle articulation angle between the two vehicle parts
and
thereby having a substantially vertical joint axle. In addition, in the
context of the
coupling of the two vehicle parts, horizontally running joint axles may be
provided,
around which these can execute movements that pitch with respect to each
other.
A drive axle is usually provided for the drive of such articulated vehicles,
the drive
axle being arranged as the last axle within the rear vehicle part and thus
pushing the
entire articulated vehicle, including the front vehicle part, via the pivot
joint. Without a
damping device arranged between the two vehicle parts, and which dampens their
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movements with respect to each other, quickly executed jack-knife movements of
the
articulated vehicle could lead to its breaking loose. For this reason, a
damping
system is arranged between the articulated parts of the hinge arrangement that
are
brought together, the system having at least one double-acting hydraulic
cylinder
serving as a shock absorber. The flow of oil between the pressure chambers of
this
hydraulic cylinder is throttled to achieve a damping effect.
A hydraulic damping system, which is intended for an articulated vehicle, is
known
from EP 1 010 608 B1. In this case, a pivot joint with a damping system
assigned
thereto is provided for the damping of the rotational movement of a pivot
joint
between two vehicle parts of an articulated vehicle, for example, an
articulated bus.
The pivot joint has two joint members which are pivotally connected to each
other by
a joint axle. The one joint member may in this case be hinged directly on the
one
vehicle part, whereas the other joint member can be pivotally connected
directly to
the other vehicle part around a horizontally running axle to compensate for
pitching
movements. The hydraulic system is controllable, whereby an improved damping
effect can be achieved when driving curves and driving straight ahead.
A parallel-connected mechanical pressure relief valve is to be provided
between the
suction and the pressure side of the damping arrangement in addition to a
proportional pressure relief valve. These two pressure relief valves are
selectively
controlled via a multi-way valve configured as a 2/2-way valve in normal
operation of
the damping arrangement, the multi-way valve is located in its flow-through
position,
in which the proportional pressure relief valve is pressurized. In case of
failure of the
control or the function of the proportional pressure relief valve, i.e., in
emergency
operation, the electromagnetically activated multi-way valve is to be moved
into a
blocking position, so that the mechanical pressure relief valve arranged in a
line
branching before it is pressurized with pressure medium from one of the
pressure
chambers.
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It is an object of the present invention to design a hydraulic damping system
of the
aforementioned type such that its function is improved and that it can be
produced
with cost-effective means.
.. Advantageous embodiments are given in the claims dependent on the claims 1
and
9, each of which taken alone or in combination with each other can represent
an
aspect of the invention.
Accordingly, a hydraulic damping system is provided for damping pivoting
.. movements of two vehicle parts connected to each other at least indirectly
via a pivot
joint, with at least one damper configured as a double-acting hydraulic
cylinder. In
this case, a double-acting can have a piston provided with two piston rods,
wherein
the respective ends of the piston rods facing away from the piston are at
least
indirectly connected to the vehicle parts. In the context of the hinge
arrangement, a
gear wheel acting together with a gear rack may also be provided, the gear
wheel
being non-rotatably connected to the rotatable joint part. The gear rack
receives the
piston of the double-acting hydraulic cylinder.
Alternatively, however, two double-acting hydraulic cylinders, each having a
piston
.. rod, may be provided, wherein the respective cylinder is connected to the
one vehicle
part and the piston rod is connected to a joint part of the other vehicle
part. In this
case, each piston-side pressure chamber of a hydraulic cylinder is connected
to a
piston rod-side pressure chamber of the other hydraulic cylinder.
.. The corresponding pressure and suction pressure chambers are connected to
each
other in both designs and arrangements of the hydraulic cylinder(s) or via a
proportional pressure relief valve. This provides for a pressure build-up in
the
pressure chamber, displaced from the pressure medium, and for a damped
pressure
drop in the corresponding damper line with a pressure-dependent opening, so
that
the movement of the piston(s) is/are damped.
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In this case, the proportional pressure relief valve is configured as an
electrically
pilot-controlled inverse proportional pressure relief valve with which a
nominal
pressure is adjustable in the de-energized state of a proportional solenoid or
in case
.. of failure of the electromagnetic actuation in the damping system. This
inverse
proportional pressure relief valve thus has a function according to which the
pressure
decreases with rising electrical input signal, while this increases with
decreasing input
signal. For example, in case of failure of the input signal or a defect of the
electromagnetic actuation, the nominal pressure can increase to the nominal
lo .. pressure as a fail-safe function, which ensures safe emergency operation
of the
articulated vehicle. A sufficient damping behavior of the damping system is
thus
obtained in such defects, so that the articulated vehicle can continue its
journey to a
workshop.
In contrast, the damping system according to EP 1 010 608 B1 has a multi-way
valve
configured as a 2/2-way valve or 3/2-way valve, which in normal operation
connects
the respective pressure chamber, the volume of which decreases, exclusively to
an
electromagnetically actuated proportional pressure relief valve. In its second
switching position, which corresponds to an emergency operation, the inflow to
the
.. electromagnetically actuated proportional pressure relief valve is blocked
and an
exclusive connection of the respective pressure chamber to a mechanically
operated
pressure relief valve arranged parallel or in series to the aforementioned
proportional
pressure relief valve is made. The latter is set to a certain minimum
pressure, which
should be in effect in emergency operation. This control of the damping system
requires a total of three valves, which increases the construction effort. In
addition, if
the control of the damping system fails, unstable driving conditions of the
vehicle, for
example, rocking, can occur, despite emergency damping characteristics of the
hydraulic system.
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In a further embodiment of the invention, it is provided that a proportional
pressure
relief valve is connected in series with the inverse proportional pressure
relief valve,
and that in an emergency operation of the damping system, a hydraulic pressure
in
the respective pressure chamber can be achieved only via the inverse
proportional
pressure relief valve. The emergency damping pressure must be able to be
lowered
to a pressure level in case of failure of the electric control to ensure the
steerability of
the articulated vehicle. A reduced damping of the movements of the pivot joint
is to
be made possible in this operation of the vehicle.
For this reason, according to the invention, a proportional pressure relief
valve, which
is preferably actuated electromagnetically, is to be connected in series to
the inverse
proportional pressure relief valve. Both proportional pressure relief valves
work
logically in an "AND" combination, so that the respective set pressures are
added
together. This thus ensures that the required hydraulic pressure is achieved
both in
the event of failure of the on-board voltage as well as in the case of
specification-
based electrical control. The electrically controlled proportional pressure
relief valve
is in this case preferably pilot-controlled, depending on driving speed.
The inverse proportional pressure relief valve is also energized in normal
driving
operation, in such a way that it assumes an inverse control function based on
the
proportional pressure relief valve. Thus, when the control current is high,
the normal
proportional pressure relief valve is set to a high pressure and the inverse
proportional pressure relief valve is set to a low pressure. At a low control
current, the
reverse pressure conditions are present. On the inlet side of the arrangement
of the
two proportional pressure relief valves, a pressure level is to be set by an
addition of
both pressures, which corresponds to the damping pressure required for the
damping, which acts in the hydraulic cylinder in each of the two movement
directions
of the piston. But if the electrical control fails, then the normal
proportional pressure
relief valve enters a position in which only a very low pressure or no
pressure is built
up, while the likewise de-energized inverse proportional pressure relief valve
sets an
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emergency damping pressure. In this case, the inverse proportional pressure
relief
valve may be connected upstream of the proportional pressure relief valve.
It is also provided that the inverse proportional pressure relief valve has a
pilot stage,
which is adjusted at a reduction or a failure of the control current in a
blocking or
throttling position and builds up a control pressure on a main piston of the
inverse
proportional pressure relief valve.
In a further embodiment of the invention, a pressure relief valve may be
connected in
parallel to the inverse proportional pressure relief valve to limit the
pressure in the
pressure chambers and the forces acting on piston rods of the at least one
hydraulic
cylinder. In this case, this pressure relief valve serving as a safety valve
should be
set to a maximum allowable pressure of the damping system, which is specified
by
the buckling safety of the piston rods. Preferably, a factor of 3 buckling
safety can be
considered in this case. For example, the electromagnetically controlled
proportional
pressure relief valve can have a range of the respective limiting pressure of
0-350
bar, wherein a maximum damping pressure of less than 200 bar results from the
addition of these pressures to the respective pressures built up by the
inverse
proportional pressure relief valve. Preferably, the parallel-connected
pressure relief
valve is set to an opening pressure of 200 bar.
Furthermore, a tank line receiving a counterbalance valve connected to a tank
can be
connected on the outlet side of a damping line receiving the inverse
proportional
pressure relief valve and the proportional pressure relief valve therefrom.
The
counterbalance valve establishes in the line sections, which are respectively
connected to the increasing pressure chamber, a preload pressure, which leads
to
the pressure chamber being forcibly filled. This prevents cavitation, which
could occur
during rapid movements of the piston arranged in the hydraulic cylinder.
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In addition, a subsequent feeding of pressure fluid in at least one of the
pressure
chambers can be achieved in that at least one of the pressure chambers is
connected to an oil reservoir of a tank via at least one double check valve.
In this
case, the at least one double check valve can be actuated via a control line
connected to one of the pressure chambers in its open position. In pressure
chambers which are configured cylindrical at a face side of the piston and
hollow
cylindrical at the other in the piston rod area, the control line can come out
of the
hollow cylindrical control chamber. The pressure generated by the proportional
pressure relief valve is supplied to the double check valve, for example, via
the
hollow cylindrical control chamber and the control line, so that this
establishes a
connection between the tank serving as equalizing tank and the cylindrical
pressure
chamber and an oil volume flow arrives in the pressure chamber.
Furthermore, the object also is achieved in a hydraulic damping system for
damping
pivoting movements of two vehicle parts connected to each other at least
indirectly
via a pivot joint, with at least one damper configured as a double-acting
hydraulic
cylinder, the pressure and suction pressure chambers of which are connected to
each other via a proportional pressure relief valve, so that at least one of
the
pressure chambers is connected to an oil reservoir of a tank via at least one
double
check valve. A corresponding possibility for a feeding of pressure medium from
an oil
reservoir should therefore also be provided if an electromagnetically pilot-
controlled
proportional pressure relief valve is only arranged in the damper line. Also,
in this
case, a return line receiving a counterbalance valve connected to the tank can
be
connected on the outlet side of the proportional pressure relief valve. Also,
cavitation
.. is prevented in the damping system by means of this counterbalance valve.
Finally, in an articulated vehicle in which two vehicle parts are at least
indirectly
pivotally connected to each other via a pivot joint and brought together by at
least
one double-acting hydraulic cylinder of a damping system, a proportional
pressure
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relief valve is to be arranged in a damping line connecting pressure and
suction
pressure chambers of the at least one hydraulic cylinder.
For further explanation of the invention, reference is made to the drawing, in
which
embodiments are shown in simplified form. They show:
Figure 1 shows a hydraulic circuit diagram of a damping system
configured
according to the invention having a double-acting hydraulic cylinder, a
damper line receiving an inverse proportional pressure relief valve and
an electromagnetically actuated proportional pressure relief valve and a
pressure relief valve connected parallel to the damper line,
Figure 2 shows a second embodiment of a damping system in which the
parallel-
connected pressure relief valve is omitted and the double-acting
hydraulic cylinder has two piston rods,
Figure 3 shows a third embodiment of a damping system in which it has
two
double-acting hydraulic cylinders,
Figure 4 shows a fourth embodiment of a damping system in which only one
electromagnetically actuated proportional pressure relief valve is
arranged in the damper line, wherein the damping system is
connectable to an oil reservoir via a counterbalance valve and double
check valves,
Figure 5 shows a fifth embodiment of a damping system which essentially
corresponds to Figure 4, wherein but in accordance with the solution
according to Figure 1, an inverse proportional pressure relief valve and
an electromagnetically actuated proportional pressure relief valve are
arranged in the damper line,
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Figure 6 shows a pivot joint arranged between two vehicle parts as a
schematic
representation, and
Figure 7 shows an inverse proportional pressure relief valve as a schematic
representation in longitudinal section.
In Figures 1, 2, 4 and 5, 1 designates a double-acting hydraulic cylinder
which has a
piston 3 provided with a piston rod 2. The piston 3 is longitudinally
displaceably
guided in a cylinder 4 and limited in this a cylindrical pressure chamber 5
and a
hollow cylindrical pressure chamber 6. Pressure lines 7 and 8 lead from the
pressure
chambers 5 and 6 to a damping circuit 9, in which the targeted conducting and
blocking of the pressure medium flow check valves 10, 11, 12 and 13 are
arranged.
Furthermore, according to Figure 1, the damping circuit 9 is bridged by a
damper line
14 which receives an inverse proportional pressure relief valve 15 and a
proportional
pressure relief valve 16 connected downstream of it. Both proportional
pressure relief
valves 15 and 16 are pilot-controlled via an electrical control current,
wherein the
corresponding control and control lines are not shown in detail. The
proportional
pressure relief valve 16 provides for a pressure change in the respective
pressure
line 7 or 8, from which it is streamed, wherein this pressurization is changed
proportionally to the electric current with which it is controlled. This
electrical current
in this case is preferably changed depending on the driving speed of an
articulated
vehicle.
The inverse proportional pressure relief valve 15 is also energized in driving
and thus
influences the pressure in the pressure lines 7 and 8 together with the
proportional
pressure relief valve 16 downstream of this. These pressure changes by means
of
the two proportional pressure relief valves 15 and 16 will be discussed in
more detail
below.
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Via the check valves 11 and 12, the pressure lines 7 and 8 are connected to
the
damping circuit 9 such that a pressure medium displaced from these pressure
chambers 5 or 6 enters the damper line 14. In contrast, the check valves 10
and 13
block a flow of the pressure medium in the damping circuit 9 in a direction
away from
the damper line 14. The pressure medium respectively displaced from one of the
pressure chambers 5 or 6 is thus selectively fed to the damper line 14.
Furthermore,
a connecting line 17, which receives a pressure relief valve 18 serving as a
safety
valve, runs parallel to the damper line 14. In addition, a tank line 19 comes
out of the
damping circuit 9, the outlet side of the damper line 14, in which a
counterbalance
valve 20, which is also configured as a pressure relief valve, is arranged.
This tank
line 19 opens into an oil reservoir 21.
As can further be seen from Figure 1, the cylindrical pressure chamber 5 is in
connection with the oil reservoir 21 via a feeding line 22, wherein a check
valve unit
23 is located within the feeding line 22. This check valve unit 23 consists of
two
double check valves 24 and 25 which can be actuated via a control line 26
connected
to the hollow cylindrical pressure chamber 6 in its open position. In
addition, a
pressure sensor designated with 27 is connected to the damping circuit 9 for
monitoring the damping system.
The function of the damping system is the following:
During straight-ahead driving or curve driving of an articulated vehicle
provided with a
hinge arrangement, for example, according to Figure 6, pressure forces act on
the
piston rod 2 and thus on the piston 3, so that the pressure of the pressure
fluid
located in the pressure chambers 5 and 6 increases in a corresponding manner.
If
this pressure increase occurs, for example, in the pressure chamber 5, it is
transmitted via the respective check valve 11 or 12 into the damping circuit 9
and is
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thus initially applied to the inverse proportional pressure relief valve 15
via the
damper line 14 and leads to its actuation depending on the amount of
pressure. The pressure medium emerging from the inverse proportional pressure
relief valve 15 passes in a second stage to the proportional pressure relief
valve 16
downstream of this, which may be adjustable, for example, to a limiting
pressure of 0-
350 bar.
The term "proportional pressure relief valve" is generally understood as
pressure
valves that convert a variable input signal continuously into a hydraulic
output signal.
The pressure medium streaming out of the damper line 14 is thus finally led
via the
proportional pressure relief valve 16 under pressure drop into the other line
section of
the damping circuit, where it passes through the check valve 10 in the hollow
cylindrical pressure chamber 6. In this case, the check valve 11 blocks this
line
section opposite of the line section of the damping circuit 9 under pressure.
A portion
of the pressure medium can flow via the counterbalance valve 20 into the oil
reservoir
21, which is required, among other things, since the volumes of the pressure
chambers 5 and 6 differ from each other due to different cross-sectional
areas.
If, on the other hand, the piston 3 moves in the direction of the hollow
cylindrical
pressure chamber 6, then in this, i.e., thus on the side of the piston rod 2,
a volume
flow is generated which passes completely via the check valve 11 into the
damper
line 14. With a corresponding pressure increase to an electrically set
limiting
pressure, this volume flow first flows through the energized inverse
proportional
pressure relief valve 15 and then the proportional pressure relief valve 16
upon
reaching the corresponding set limiting pressure, in order to then flow
through the
open check valve 13 and the pressure line 8 into the pressure chamber 5.
The pressure thereby generated by the proportional pressure relief valve 16 in
the
pressure chamber 6 is transmitted via the control line 26 to the double check
valve
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unit 23. This establishes a connection between the oil reservoir 21 and the
pressure
chamber 5, so that a missing oil volume can be compensated. So that
this amount of oil can be fed from the oil reservoir 21, this is provided with
a
ventilation having a ventilation filter 28, via which a corresponding amount
of air flows
into the oil reservoir 21 or exits again from this.
The positive effect of this type of feeding is that the flow of oil into the
pressure
chamber 5 does not have to overcome the pressure difference of a spring-loaded
check valve, but that it flows through the forced open check valves 24 and 25.
Feeding would have to be otherwise overcome, i.e., when using a simple check
valve
which has no external actuation, the pressure difference in the check valve,
which is
proportionately added among others from the flow resistance and the preload
pressure of the check valve spring. The flow resistance depends on the amount
of
the flowing oil volume flow and the viscosity of the hydraulic medium.
With increasing travel speed of the piston 3 and increasing viscosity, i.e.,
thus in
particular with decreasing oil temperature, the pressure difference increases.
When
the pressure difference is higher than the atmospheric pressure in the oil
reservoir,
cavitation occurs. This can thus be effectively prevented by the invention. A
corresponding feeding in the pressure chamber 6 via a controlled valve unit is
not
required, since this is always forcibly filled with the pressure set at the
counterbalance valve 20.
The inverse proportional pressure relief valve 15 is configured such that it
can set a
nominal pressure in the de-energized state of a proportional solenoid provided
in its
pilot control unit or, in case of failure of the electromagnetic actuation, in
the damping
system. It has a function according to which the pressure generated in the
respective
pressure line 7 or 8 drops with an increasing electrical input signal,
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whereas this increases with a decreasing input signal. Thus, the effect of the
inverse
proportional pressure relief valve 15 is opposite the proportional pressure
relief valve
16 following this in the damper line 14.
__ According to the invention, it is now provided that these two proportional
pressure
relief valves 15 and 16 are coordinated with each other with respect to their
pressure
profiles so that a specific damping pressure can be set via this unit as a
function of
the respective driving conditions of the articulated vehicle. As is apparent
from Figure
1, for example, the proportional pressure relief valve 16 should have a
controllable
limiting pressure of 0-350 bar. In contrast, the inverse proportional pressure
relief
valve 15 will have a lowest value of the limiting pressure, which is
predetermined in
order to safely drive the articulated vehicle to the next workshop in the
emergency
operation of the damping system.
In normal operation of the damping device, however, as already explained, the
respective limiting pressures of both proportional pressure relief valves 15
and 16 are
to be added, so that in each case a predetermined amount of the limiting
pressure is
reached. Moreover, it is also possible to ensure both normal operation and
emergency operation only by means of the inverse proportional pressure relief
valve
__ 15, thus without the additional proportional pressure relief valve 16, when
the inverse
proportional pressure relief valve 15 can be set to a very low pressure in
normal
operation, but in emergency mode, i.e., when it reaches a de-energized state
through
a defect, sets the nominal pressure to a higher nominal pressure as a fail-
safe
function.
In contrast to Figure 1, Figure 2 shows the double-acting hydraulic cylinder 1
in a
design in which it has a further piston rod 2'. In addition, in this case, the
damping
system consists only of the damping circuit 9 and the damper line 14 with the
inverse
proportional pressure relief valve 15 and the proportional pressure relief
valve 16. In
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this case, therefore, both a connecting line having a further pressure relief
valve and
an oil reservoir having a tank line, a counterbalance valve and a
device for feeding the pressure medium has been dispensed with. The double-
acting
hydraulic cylinder 1 has two pressure chambers 6 and 6', which are both
configured
as a hollow cylinder.
As far as the damping circuit 9, the damper line 14 and the proportional
pressure
relief valves 15 and 16 are concerned, the arrangement according to Figure 3
essentially corresponds to the arrangement according to Figure 2, wherein in
this
case, however, two double-acting hydraulic cylinders 1 and 1' are used. In
this case,
the pressure line 7 is connected to the cylindrical pressure chamber 5' of the
hydraulic cylinder 1' and to the hollow cylindrical pressure chamber 6 of the
hydraulic
cylinder 1. Furthermore, the pressure chambers 6' and 5 are brought together
and
connected to the pressure line 8.
According to Figures 4 and 5, in accordance with Figure 1, a feeding device is
associated with the pressure chamber 5, which contains the already explained
oil
reservoir, the check valve unit 23 and the control line 26. In addition, the
tank line
with the counterbalance valve 20 arranged therein comes out of the damper
circuit 9.
In the embodiment according to Figure 4, only the electrically pilot-
controlled
proportional pressure relief valve 16 is arranged in the damper line 14.
According to
Figure 5, both the inverse proportional pressure relief valve 15 and the
electrically
pilot-controlled proportional pressure relief valve 16 are arranged in the
damper line
14. In both cases, the connecting line having the pressure relief valve was
dispensed
with.
Figure 6 shows a hinge arrangement 29 for an articulated vehicle (not shown in
greater detail), which should preferably be configured as an articulated bus.
This
consists of a front vehicle part 30 and a rear vehicle part 31, which are
connected to
each other via a pivot joint 32. Preferably, the articulated vehicle is driven
by a drive
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axle not shown, which is located in the rear vehicle part. The vehicle parts
30 and 31
are brought together via the double-acting hydraulic cylinders 1 and 1' of the
above-
described damping system such that they are stabilized during a straight-ahead
driving or curve driving, i.e., can not break loose.
A possible embodiment of the inverse proportional pressure relief valve 15 is
shown
as a schematic representation of Figure 7. Accordingly, the proportional
pressure
relief valve 15 has a housing 33 in which a main valve 34 and a pilot stage 35
are
arranged. The pilot stage 35 has an armature 36 and coils 37, wherein the
armature
36 has a poppet valve body 38 which works with a valve seat 39 provided in the
housing 33. The main valve 34 consists of a control piston 41 displaceably
guided in
the housing 33 and supported via a valve spring 40 in this. The control piston
41 is
pressurized via a first connection 42 of the housing 33 with the pressure from
one of
the pressure chambers (see Figure 1; pressure chambers 5 or 6) and displaced
against the force of the valve spring 40 until the
pressure medium passes over in a second connection 43, which should be
connected to the damper line 14. Via the poppet valve body 38, on the back of
which
a hydraulic control pressure acts via a control line 44, the pressure to be
limited can
be adjusted continuously.
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Reference numerals
1 double-acting hydraulic cylinder
1' double-acting hydraulic cylinder
2 piston rod
2' piston rod
3 piston
3 piston
4 cylinder
4 cylinder
5 cylindrical pressure chamber
5 cylindrical pressure chamber
6 hollow cylindrical pressure chamber
6 cylindrical pressure chamber
7 pressure line
8 pressure line
9 damping circuit
10 check valve
11 check valve
12 check valve
13 check valve
14 damper line
15 inverse proportional pressure relief valve
16 proportional pressure relief valve
17 connection line
18 pressure relief valve
19 tank line
20 counterbalance valve
21 oil reservoir
22 feeding line
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23 check valve unit
24 double check valve
25 double check valve
26 control line
27 pressure sensor
28 ventilation filter
29 hinge arrangement
30 front vehicle part
31 rear vehicle part
32 pivot joint
33 housing of 15
34 main valve of 15
35 pilot stage of 15
36 armature of 35
37 coils of 35
38 poppet valve body of 35
39 valve seat
40 valve spring of 34
41 control piston of 34
42 first connection of 15
43 second connection of 15
44 control line
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