Note: Descriptions are shown in the official language in which they were submitted.
1)137
The present invention relates to a valve having valve
member biassed against a valve seat by a spring and which rests,
in the open position, against a detent, and to the use of said
valve.
Valves of this type are known, as fo~ example, in a
device for equalizing and controlling the pressure in at least
two pressure chambers, particularly in pneumatic tires of a vehicle
according to the German Offenlegungsschrift No. 2,822,514. In
this type of valve, the valve member is to open at a specific
higher pressure and to close at a specific lower pressure.
However, it is disadvantageous that at low pressures and at
small pressure differences of the opening and closing pressure,
the valve member has inaccuracies and its ability to respond
scatters to some extent.
German Paten-t No. 1,048,452 disc]oses a check valve
or excess-pressure valve in which a permanent magnet is used
instead of a biassing spring in order to attain the restoring
force. This valve functions practically only in a vertical
position at rest, otherwise the magnet can move out of the
effective field of the housing and is rendered ineffective.
Furthermore, this valve is extremely sensitive to vibrations,
which can cause undesired closure. This valve is absolutely
unsuitable for contro]ling pneumatic tires of a vehicle.
The present invention improves the accuracy of response
of the valve mentioned at the outset, particularly also in cases
of low pressures and small differences of both the opening pressure
and the closing pressure.
According to the present invention there is provided
in a valve having valve member biassed against a valve seat by
a spring and which rests, in the open position, against a detent,
the improvement in which the valve member or a housing for the
valve member is provided with a magnet which interacts with a
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ferromagnetic deten-t on the housing or the valve member such that
when the valve member is closed, the magnet at least approximate-
ly abuts the ferromagnetic detent and when the valve member is
open said magnet is spaced therefrom by a distance at which
the biassing force of the magnet is smaller than that of the
spring.
As soon as the valve member begins to respond, i~e.,
to close, when the pressure drops the attraction between the
magnet and the ferromagnetic detent increases. As soon as the
decrease in the biassing force of the spring caused by the
closing motion of the valve member is compensated for or
exceeded bv the increase in the biassina force of the magnet
the valve member suddenly closes. Precise closing can thus be
attained even at low pressures and small pressure differences.
The biassing force of the spring which is increased when the
valve is open and the practically absent effect of the rnagnet
assure that the valve is reliably kept open in any position
of the valve and even at extreme vibrations, as for example,
when using the valve for controlling pneumatic tires of vehicles.
In one embodiment of the present invention the space
bet~een the ferromagnetic detent and the magnet is adjustable.
This design of the valve permits the adjustment of the sensitivity
to respond and/or of the level of the pressure of response.
Suitably the fermagnetic detent is adjustable. Alternatively the
magnet is adjustable. Yet aqain the detent of the valve may be
adjustable.
The magnet may be an electromagnet, a permanent magnet
being preferred. In the latter case it is particularly advantageous
that the magnet is a pot-shaped magnet disposed on a rod of the
valve member and said pot-shaped magnet interacts with a ferro-
magnetic detent in the housing.
Particularly when the valve is exposed to frequent changes
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of position and vibration the rod is provided on the side of the
maqnet, with a lonaitudinal quide is favourable.
The valve is suitable for the most varied purposes.
Mowever, its use is particularly favourable in a device
for controlling the pressure in at least one pressure chamber
the valve memker closing a pressure chamber so as to render it
impervious to the medium, said pressure chamber beinq provided
with a lockable supply pipe, the connecting duct of -the pressure
chamber opening into the valve seat and being closable by means of
the valve member and the cross-sectional area of the orifice of
the connecting duct being smaller than the free area of the valve
member turned towards the pressure chamber. Specifically
the valve is useful such a device for the additional equalization
of the pressure in at ]east two pressure chambers, all connecting
ducts of the pressure chambers opening into the valve seat and
being closable by means of the valve member and the sum of the
cross-sectional areas of all orifices of the connecting ducts
being smaller than the free area of the valve member facinc3 the
pressure chamber. Suitably the pressure chamber is a set of
pneumatic tires of a vehicle such a device is described, for
example, in the German Offenlegungsschrift No. 2,822,514.
A practical example of the valve according to the
present invention is a device for equalizinq and controlling the
pressure in at least two pressure chambers, particularly in
pneumatic tires of a vehicle is described in greater detail
hereafter with reference to the accompanying drawings in which:
Figure 1 is a longitudinal section of a valve in the
device;
~igure 2 is a plan view of the device of Figure l; and
Figure 3 is a detail of the device of Figure 1 on an
enlarged scale.
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Tlle device for equ~lizing and controlling the pressure
in at least two pressure chambers is provided with a valve. Said
device is suitable particularly for pneumatic tires of vehicles.
The device has a pressure chamber 1 whose one wall is formed
by a valve member 2, which is biassed against a valve seat 4 by
means of a biassing spring 3. A supply pipe 5, which can he
closed by means of a check valve 6, opens into the pressure chamber
1. Connecting ducts 7 and 8 serve for junction with the pressure
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iiL~t~0~37
chamher (not shown) and are for example, pneumatic tires ofvehicles. soth the connecting duct 7 and the connecting duct 8
open into the valve seat ~. The free area of the valve member
which faces the pressure chamber is substantially larger than the
sum of the cross-sectional areas of the orifices 9 and 10 of the
connecting ducts 7 and 8.
Referring particularly to Figure 3 the orifices9 and 10
are provided with sealing lips 11, which face the valve member 2.
Said valve member 2 is provided with a gasket 12 facing the sealing
lips 11. The gasket 12 consists of an elastic material which can
be displaced bv the sealing lips 11 so that a reliable seal
hetween the valve member and the orifices is assured.
The valve member 2 is formed by a piston 13, which is
secured to a rod ~and is taper bore mounted. The piston 13
is disposed in a cylindrical housing 15 whose bottom is divided
into two regions, a first bottom region forming the valve seat
4 and a second bottom region Eorming a wall portion of the pressure
chamber 1. A corrugated tube sleeve 17 serves for sealinq the
piston 13 against the cy]inder wall. Said corrugated tube s]eeve
17 is disposed on the piston 13 on the one hand and via an internal
ring 18 on the cylinder wall on the other so as to render it
impervious to the medium. The biassing spring 3 serves for
biassing the piston 13 aqainst the valve seat 4. The biassinq
force of the biassing spring may be adjusted by means of a setscrew
19 screwed into the housinq 15. The opening motion of the piston
13 and thus of the valve member is limited by a detent 20, which
is adiustable when re~uired.
A pot-shaped permanent magnet 21 is secured to the end
of the rod 14 which it faces away from the valve member 2. Said
permanent magnet 21 interacts with a ferromagnetic detent 22,
which is screwed, in the form of a ring, into the housing 15.
Depending on the screwed-in depth the space X between the
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permanent magnet 21 and the ferromagnetlc detent 22 can be
adjusted when the valve rnember 2 is open. A screw cap 23 is
screwed to the end of the housing 15 and completely seals off the
device.
The screw cap 23 can be provided with a pin 24, which
engages a borehole 25 of the rod 14 and serves for guiding said
rod. The screw cap may consist of a transparent material so that
the position of the permanent magnet 21 and thus the control state
of the valve can be seen.
To adjust the space X the ferromagnetic detent 22 can
a]so be fixed when required and the permanent magnet 21 can be
such that it is screwable on the rod in the axial direction. It
is also possible to so design the detent 20 that it is adjustable
in order to vary the space X.
To equalize and contro] the pressure in -the pneumatic
tires of a vehicle the device may be designed, for example, as
follows:- If the nominal pressure in a tire is to be, for
examp]e 8 bars, the valve member 2 opens when a pressure of at
least 9 bars is applied at the supply pipe 5. The valve member 2
closes as soon as the pressure in the pressure chamber 1 drops to
below 7.5 bars. When the pneumatic tires are inflated -to the
nominal pressure of 8 bars via the supply pipe 5, the pressure
chamber 1 and the connecting ducts 7 and 8, then the valve
member 2 thus remains open. When the pressure in one of the
pneumatic tires drops then the valve member 2 remains open and
the pressure can be equlized from one connecting duct via the
pressure chamber into the other connecting duct. Only when the
total pressure drops to a value lower than the nominal pressure,
i.e., to lower than 8 bars in the present example, does the valve
member 2 begin to close. In the first phase only the biassing
force of the biassing spring 3 acts and the rod 14 with the valve
member 2 is moved towards the valve seat 4. After a spring
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137
elongation of approximately 1 mm the influence of both the per~
manent magnet 21 and the detent 22 becomes effective in a second
phase and the valve closes with a jolt. In the first phase the
space X is so large that the permanent magnet 21 is ineffective.-
Thus, there exisis no danger that, without pressure loss in the
pressure chamber 1, the valve closes automatically upon a
possible impact and does so independently of the position of the
valve.
When the valve member 2 is closed and the pressure
in one of the pneumatic tires rises again, for example, due to
excessive heating, then this pressure rise cannot open the valve
member 2 since the pressure applied to the valve member 2 through
the cross section of the orifice acts only on an area of the valve
member which corresponds to the cross section of the orifice.
Even if this pressure is substantially higher than the nominal
pressure of the tire, it is high enough to open the valve member.
This thus ensures that once a valve member 2 is closed it cannot
be opened by an excess pressure in the connected pressure
chambers. It can be opened only by renewed supply of pressure
medium via the supply pipe 5.
In case of a sudden pressure drop in one of the pressure
chambers the valve member 2 closes immediately even at excess
pressure.
The device is also suitable for pressures of e.g.,
2 to 5 bars.
The valve member may also be a diaphragm inserted bet-
ween the walls of a pressure chamber.
