Note: Descriptions are shown in the official language in which they were submitted.
~253a8~33
Gas Suspension for Vehicles, specifically
for Railway Vehicles
This invention relates to a gafi-suspension system in
accordance with he generic definition in ~laim 1
hereof.
Conventionally, gas springs such as in the form of spring bellows
or ~pring.~ags, are proyided between the running gear and
the vehicle body of ral~ay vehicles. Generally, the
spring bags in these systems are arranged in pairs or
in pai.red groups transversely opposite to the longitudinal
centre-line of the vehicle or travelling direction,
i.e. so that for each. spr~ng bag on one side of the
rail~ay ~ehicle there is a spring bag on the other
side.
For valve b~g ~ystems of the conventional type, valve
devices have been disclosed (German Patent Specification
1.088 086~ by means of which sta~ilizing of the vehicle
against xolling of the body about its longitudinal centre-
line is achieved. Such valve devices are formed as double-
acting adjustable relief va~ves which., starting from a
pre~et pressure difference between the gas sprinys or
gas spxing groups, interconnect these. A sudden re-
duction of the pressure in one of ~he:spring bags ~ill
cause the pressure in the P spring ~ag to be reduced,
too~ b~ e~ecting pressur~ equalization ~et~een the spring
~,6
_ 3 ~ 3~
bags. An inherent feature of the relief valves used is
that they operate w~th a certain pressure d~f~exential
since th.ey are equipped w;th a comprcssion spring of
a pre-determined spring force acting i~ the closing
direction. If one of the spring hags or one of the
spring bag groups bursts, problems of unsufficient sta-
~ilization of the'vehicle hody are liable to arise due
to t~e differential pressure behaviour, i.e. due to
the existence of a residual pressure in one of the
spring bags. 5hould the pressure in one of the spring
hags decrease to zero in...consequence of the bag bursting,
then it i~ undesirable 'if such a residual pressure re-
mains in the other spring bag which ~s liable to con-
tribute to an unstahle-position of the vehicle body.
Similar di.sadvantages will naturally exist under condi-
ti,ons ~here no bursting of the spring bags occurs, but
a sudden decrease to a very- low minim~Lm pressure level.
Starting on these premises, it is the object of the
invention to de~elop a gas ~suspension of the generic
kind referred to so that the pressure characteristi~ of
conventional valves causing the'stabilizing problems
can hè'avoided. It is intended with.the aid of simple
design means to enable the't~o spring ~ags to ~e
adjusted for a certain pressure:without any remaining
pressure'differential or to deflate'them co,mpletely if
a preset minimum press~re is reached or oIle of the
spring bags has hurst.
Th~s ob.ject:is achieved by means of the featur~s defined
in the'characterizing par-t of Cla~m l.hereof.
The valve'device:interconnecting the'two ,spring bags
which may-he'referred to as a reIief val~e'between the
spring bags is provided with'a physIcall~ simple'feature
~hlch.eIiminates the. resi.dual pxe5sure'hehaviour hecause
the force.of a spring ~ecomes efectiv~:at a level belo~
an arbitrarily pre-determinable'pres~u~e,' i.eO on reaching
9~2~i3E3~3~
_ 4
a switching level, said spring disa~ling the compression
spring of the check valve which is respQn~ihle ~or the
residual pressure ~ehaviour. If either of the spring bags
bursts or if its pressure drops to an extremely low
minimum level, th~n one of the check valves is disabled
in a manner t~at the valve is maintained in its open
position and a connection established between the two
spring bags. At the moment one of the spring ~ags bursts,
the o-ther intact spring bags will as a result be
instantly deflated through the ~urst spring bag.
T~e spring deuice coming into action by a switching
pressur~, i.e. on the pressure in one of the spring bags
dropping, may also ~e ~sed for a val~e arrangement
comprising two pressure-~alanced stop valves, i.e. two
valve arrangements with ~alanced valve elements which
will not open ~f different pressures exist on the two
sides of the ~alve eIement, i.e. under a differential
pressure. In addition to th reIief valve formed by the
two stop valves with the spring auxiliary device, a
conventional relief valve'may be provided, i.e. a
reIief valve with two check valves.
~eference is made to the patent claims ~or advantageous
embodiments and further developments.
T~e'invention is expla~ned on the strength of typical
embodiments ~ith reference to the accompanying drawing.
Fig. 1 is a sch~matic diagram of a gas suspension
with a reIief ~alve'device according to the
invention;
Fig. 2 is a diagram comparahle'~ith Fig. 1 where
a xeIief valve'is used with,'two pxessure~
~a~anced stop valves.
Fig. 1 of t~e dra~ing sho~s a reIie~ ~al~e'1 which is
located ~n the'connection ~etween t~o ,~chematically re-
pxesented spring bags 3 and 5. The spr~ng ~ags 3 and 5
i3~38~3
- are disposed in a manner known per se transverse to
the veh~cle centre-line opposite each ~thex, acting
between t~e vehicle superstructure, e,g. in the form o~
a car body, and the running gear of a railway vehicle.
The two spring ~ags are connected via lines 7 and 9 to
the relief valve 1; the lines 7 and 9 may be formed also
in a conventional manner by a frame mem~er of the rail-
way vehicle~
The xelief valve 1 is provided with two check valves 11
and 13. The check valve 1t shown on the left hand side
in Fig. 1 of the drawing acts ~etween two pressure spaces
15 and 17 of w~ich the pressure space 15 is connected
with.the Iine 7, whereas the pressure space 17 communicates
with the line 90 The check valve 13 shown on the right
hand side acts ~etween two pressure spaces 19 and 21 of
which the pressure space 19 communicates with the line
7 and, consequehtly, with the pressure space 15, whereas
the pre.ssure space 21 communicates with.the line 9 and,
consequently, also with the pressure space 17. The check
valve 11 as weIl as the check valve 13 may be constructed
in the simplest form, i.e. the check valve 11 comprises
a compressi.on spring 23 which. is capable of pressing a
valve disc on~o a valve seat, whereas the check valve
-13 is also provided with a compre~sion spring 25 which
forces a ~alve disc onto a valve seat. The two check
valves 11 and 13'operat~e according to the
principle of differenti.al pressure valves which is known per se.
If~f~r -ihstance~ there is a pressure differential of 5 bar bet-
ween the'pressure space:17 and the pressure space 15 such
that the'pressure'in the'pressure'space'17 is, say, 5
bar higher than the'pressure in the pressure. space 15,
then the check ~alves 11 will open ayainst the force of
the compress'ion spring ?3 and pressure equalization will
take place ~etween the pressure'spaces~7 and 15 and,
consequently, between the spring ~ags. 5 and 3.' The same
applie.s to the chec~ valve 13. nithDut the's~stem
accordin~ to th invention descri~ed ~n the following, a
so-called residual pressure'~ehaYi~ux ~ould occur with
~2~i388~
the two check valves, i~e. th.e ch ck.~al~e 1~ would
normally close at a pressure differential of, say, 1.5
~ar, i.e. under conditions when the pressure in the
pressure-;space 17 i5` 1.5 bar higher than the pressure in
the pressure space 15 because the valve element of the
check valve 11 is pressed with a pre-determined force
of the compression spring 23 onto its valve seat.
According to the invent~on, a system is provided which
i.s capakle of effecting complete pressure equalization
~etween the spring ~ags 3 and 5 below a pre-determined
adjustable pressure'level, i.e, if one of the spring bags
3 and 5 should burst, then the other opposite spring hag
~ill be completely deflated through the burst spring bag.
As shown in the illustration, the ~alve disc 29 acting
relative to the valve seat 27 of the check valve 11 can
~e actuated by a piston shank 3~ connected to a piston
33~ In the same fashion, a piston shank 39 connected to
a p~ston 41 can actuate the valve disc 37 which cooperates
with the ~alve seat 35.of the check.valve 13. In the
exa~ple`illustrated, a common spring 43'acts on the two
pistons 33 and 4~, ~he piston 33 ~eing movable between
two stops 4S and 47 whereas the piston 41 is movable
~etween two stops 49 and 51. The force of the spring 43
is greater than that of the compression spring 23:
similarl~, the'force of the spring 43 is greater th~n that
of the compresfiion spring 25. Consequently, the two check
Yalves 11 a~d 13 feature a similar layout and similar co-
action.
The operation of the reIief valve according to the in-
vention is as ollows:
The'reli.ef valve operates up to an adjustable pressure of,
sa~, 1 b~r ~n the normal manner, i.e.' up to an ad~ustahle
pressure Qf 1 bar in one of the:lines 7 and 9, the check
val~es 11 and 13'operate'without the:additional functions
of the pistons 33 and 41. If the pressure in one of the
pressure'spaces 17 or ~g drops to a ~alue of below 1.har,
-~ ~ 7 ~ ~ ~5388~
then the force of the spring 40 is capable of over-
coming the counterforce produced hy the pressure, i.e.
in this case, thR piston 33 is displaced to the left
h~nd side as shown or, respecti~ely, the piston 41 is
displaced towards the right hand side as shown. Upwards
of the pressure o~ ; ~ar, the two pistons will consequent-
ly ~e kept in contact with the inner stops 47 or 49
respectively so that the end of t~e respective piston
shank 31 or 39 respectively ~s at a distance from the
valve disc of the check valve facing it. In this re-
lative position, the check valves operate in the normal
manner as explained in the foregoing.
s
Let is be assumed that- the pressure in the two spring
bags 3 and 5 is, say, 5 bar and that the spring bag 3
bursts suddenly. Due to the bursting of the bag, the
pressure inside the pressure chamber 19 drops to a
level ~elow 1 bar ~ithin a short period of time; when
a level of ~elow 1 bar, the so-called switching pressure
is reached, the force of the spring 43 i5 able to dis- -
place the piston 41 to the right hand side as shown.
The piston sh~nk 39 connected to the piston 41 now
moves against the valv~ disc 37 and lifts it off its
valve seat 35. In this manner, an open connection is
esta~lished between the burst sprLng bag 3 and the
spring bag 5 so that complete deflation of the spring
bag 5 is effected within a very short period of time
through the pressure space 21, the pressure space 19,
t~e line 7 and the burst spring bag 3. Deflation is
complete, that is without ~the residual pressure behaviour
characteristic of check val~es, because the force of
the spring 43 e~lminates the counterforce of the
co~pression spring 25 and, as a result, the valve disc
37 is m~intained open.
The orce to be overcome:additionally ~y the spring 43
as the Yalve disc 37 is lifted off the.valve seat 35
which force is exerted by the compres.~ion spring 25
and t~e pressure in the`pres~ure:space 21 has been
B
- 8 _ ~ ~538~
assumed in the foregoing to be negligihle, i.e. it has
been as~umed that the connection via the check valve
13 is esta~l~shed immediateIy when the pressure inside
the pressure space 19 drops to the so-called switching
pressure. Under certain pressure conditions and physical
configurations, it is of course also possible for pressure
equalization to take place initially in the check valve
11 in the conventional manner ~efore the valve seat 37
is pushed open in the manner desci~ed above by the now
prevailing force o~ the spring 43.
~hen the piston 41 has lifted off the valve disc 37 with
its piston shank 3~, then a comparable condition will
occur in the region of the check valve'~1. If the pressure
inside the pressure space 17 has dropped to a level below
1 bar due to the rapid deflation described a~ove, i.e.
the switching pressure, then the piston 33 will become
active in a comparable manner, i.e. the spring 43~will
be capable of displacing the piston 33'towards the left
hand side asdshDwn so that the pistonshank 31 lifts the
valve disc 29 off its valve seat and establishes a
constantly open connection between the pressure space 17
and the pressure space 15 in a comparable manner. Complete
deflation of the spring bag 5 can now take place via both
check valves ~1 and 13 in the direction of the burst spring
bag 3. Since the pressures in the t~o spring bags are
completely equalized within a minimum of t~me, the un-
desirable 'hazard of tilting of the vehicle body, i.e.
the'ha7ard of instability of the complete rail vehicle,
is excluded.
The invention is not limited to the construction
illustrated of the pistons 33'and 41 with the common spring
43'although such a p~ysical integration may be desirea~le.
Thus, it is also possibIe for the reIief valve to con-
sist of t~o physical separated check valves each'having
allied to it separately a cas~ng ~th an individual
spring to load the pistons 33 and 4~ respectiveIy. Tn the
~ _ 9 ~ 3~
s.ame manner, it is of cours.e also possihle to make the
switching pressure which initiates the open connection
between the two spring ~ags varia~le in such a manner
that the function of the pistons 33 and 41 respectively
can take place already at a pressure higher than 1 bar.
In principle, the connection of the two spring bags is
effected that only wh n one of the spring bags bursts,
~ut also at a preset minimum pressure where the hazard
o~ tiltin~ of the car body is to ~e eliminated.
The relief valve 53 illustrated in Fig~ 2 of the drawing
according to another embodiment of the invention is
e~uipped with two balanced stop valves 55 and 57. The
t~o stop valves are pressure-balanced, i.e. the valve
element 59 or 61 respectively has equal pressures
acting on its two sides. Due to the hole inside the
valve element 59, the pressure of the pressure space 63
also exists in pressure space 65; Since the same pressure
acts on the same areas, the stoPvalve 55 cannot act as
a pressure differential valve'if a pressure difference
should exi~t inside the lines 67 and 69 leading to the
spring ~ag~ 3 and 5. The valve element 59 is forced on-
to its valve se.at solely by the force of the spring 71
and, in the process, interrupts th.e connection between
the pressure fipace 63 and the pre~sure space 73. The
configuration and method of operation of the stop valve
57 are analo~ous. .~
5imi.1ar to the embodiment illustrated in Fig. 1, the
stopvalves 55 and 57 have a device allied to them
comprising pistons 33 and 41 respectively and piston
shanks 31 and 39 respectively~ Likewise., a spring 43
is provided analogous to the embodiment described
above ~hich îs capable of prefising both ~istons 33 and
41 respectively in the direction of their allied valve'
element. Onl.y ~ith.the aid of thi.s device is it possible
for eIther of the t~o stop valves 55 or 57 or both ~top
valv~s to open~ 'Shsuld, in the'case'of the'arrangement
~5i38B9
- 10
illus.trated in Pig~ 2, a ~witching press.ure havz been
selected helow ~ ~ar, then the force of the spring 43
is a~le to oye.rcome the pneumatic ~orce acting on the
opposi.te side of the piston 33 and 41 respectively when
same decreases to below 1 bar so t~at in th~s case the
piston shank 31 or 39 becomes effective ~n respect of
the contiguous valve ~lement 59 or 61 respecti~ely to
displace it against the force of the spring 71 or 75
respectively. Again it is necessary in this case for the
spring 43 to have a greater spring force than the spring
71 or 75 respectively. Thus, i~ the spring bag 3
communicating with the line 67 should burst, the action
described ~ith reference to Fig. 1 would again take
place. Since the pressure inside the pressure space 77
(which also prevails in pressure space 73~ quickly de-
creases below the value of 1 bar, the spring 43 will
force the piston 41 with its piston shank 39 directed to
th.e right hand side against the valve element 61 to lift
the latter against the force of the spring 75 off its
valve seat. As a result, the connecti.on between the spring
bag 5 and the burst spring bag 3 will be opened with a
large cross-sectional area, i.e. the spring bag 5 will
have its pres~use reduced through the burst spring bag
3 when the pressure in the pressure space 77 falls below
1 bar. The condi.tions in the case of spring bag 5 bursting
are analogous.
In contrast to the embodi~ent illustrated in Fig. 1, the
reIief valve 53 will be effecti~ only if a switching
. .. . .
pre~sure'beIow 1 ~ar is re~hed in one of the lines 67
or 69 respectivel~. Above this switching pre.ssure, the
reIief valve remain~ inactive in the absence of pressure
differential behaviour, in other words, i~t will remain
inactive even if a relatively high.pressure di~erential
should exist bet~een the lines 67'and 69 and, respectively,
the spring bags 3'and 5~
~i38~
-- 1l
It is within the scope of the concept of the present
invention to provide a relief ~alve 79 acting in a m~nner
known per se in addition to the relie~ valve 53,
i.e. connected in parallel with it (Fig. 2). In this
case, the relief valve 79 serves to effect pressure
equalization between the spring bags if there should
be a pressure differential of more than, say, 1.5 bar.
Below a pressure of, say, 1 har, preferably in the case
of one the spring hags bursting, the relief valve 53
would serve to interconnect the two spring bags 3 and
5 to bring ahout complete pressure equalization~
- 12 _ ~2538
51 Stop
53 ReIief valve
Stop valve
57 Stop valve
59 Valve element
61 Valve element
63 Press.ure space
Pressure space
67 Line
6q Line
71 Sprin~
73 Pressure space
Spring
77 Pressure ~pace
7q Relief ~alYe
