U.S. patent application number 09/804215 was filed with the patent office on 2001-09-27 for pneumatic spring with oscillation damper adjusted as a function of the support pressure.
This patent application is currently assigned to Mannesmann Sachs AG. Invention is credited to Pradel, Robert.
Application Number | 20010024004 09/804215 |
Document ID | / |
Family ID | 7636073 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024004 |
Kind Code |
A1 |
Pradel, Robert |
September 27, 2001 |
Pneumatic spring with oscillation damper adjusted as a function of
the support pressure
Abstract
Spring strut with a pneumatic spring and an oscillation damper
which can be adjusted as a function of the support pressure. The
pneumatic spring has a spring space bounded by a U-type bellows,
which spring space is pneumatically connected to a damping device
which can be adjusted as a function of a support pressure. A
component which having a duct connects the spring space and the
damping device is embodied without a hose and is integrated in the
spring strut in such a way that it does not form any essential
surface change in an unrolling piston associated with the U-type
bellows and the unrolling piston forms at least a part of this
duct.
Inventors: |
Pradel, Robert; (Heidenfeld,
DE) |
Correspondence
Address: |
Thomas C. Pontani, Esq.
Cohen, Pontani, Lieberman & Pavane
Suite 1210
551 Fifth Avenue
New York
NY
10176
US
|
Assignee: |
Mannesmann Sachs AG
|
Family ID: |
7636073 |
Appl. No.: |
09/804215 |
Filed: |
March 12, 2001 |
Current U.S.
Class: |
267/64.27 ;
267/122 |
Current CPC
Class: |
B60G 2206/424 20130101;
F16F 9/05 20130101; B60G 2500/204 20130101; B60G 2400/518 20130101;
B60G 17/044 20130101; B60G 2400/51 20130101; B60G 17/0485 20130101;
B60G 2202/314 20130101; B60G 2204/1262 20130101; F16F 9/512
20130101; B60G 2202/152 20130101 |
Class at
Publication: |
267/64.27 ;
267/122 |
International
Class: |
F16F 009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2000 |
DE |
100 14 467.5 |
Claims
I claim:
1. A spring strut comprising an oscillation damper having a
container and a damping device which can be modified as a function
of pressure, an unrolling piston fitted to the container, a U-type
bellows bounding a spring space, said bellows riding on the
unrolling piston and being connected to one of the container and
the unrolling piston, and a duct which pneumatically connects the
spring space and the damping device, said duct being configured
without a hose and being integrated into the spring strut, said
duct having a section which is formed by the unrolling piston.
2. A spring strut as claimed in claim 1 wherein the unrolling
piston comprises support ribs which are received against the
container, said section of duct being arranged between two of said
support ribs.
3. A spring strut as claimed in claim 1 wherein the unrolling
piston comprises an extension which can be connected to the damping
device.
4. A spring strut as claimed in claim 3 wherein said extension
comprises a connecting part provided with a section of the
duct.
5. A spring strut as claimed in claim 4 wherein the unrolling
piston has a connection hole and the connecting part has a
connection mouthpiece which accommodates a seals, said connection
mouthpiece engaging said connection hole in said unrolling
piston.
6. A spring strut as claimed in claim 5 wherein said mouthpiece
comprises spring tongues which are received in the connection hole,
each said spring tongue having a protrusion which engages behind
the hole in a snap connection.
7. A spring strut as claim din claim 4 wherein the unrolling piston
has an outer contour interrupted by a recess which receives the
connecting part, and the connecting part has an outer surface which
conforms to the outer contour of the unrolling piston.
8. A spring strut as claimed in claim 4 wherein the connecting part
comprises a connection having a seal which seals the connection to
the damping device.
9. A spring strut as claimed in claim 9 wherein the damping device
comprises a housing cap having a hole, the connection being
configured as a spigot which forms a plug-in connection with the
hole in the housing cap.
10. A spring strut as claimed in claim 9 wherein the spigot and the
hole in the housing cap have a common centerline which is parallel
to a centerline of the spring strut.
11. A spring strut as claimed in claim 9 wherein the spigot and the
hole in the housing cap have a common centerline which is
perpendicular to a centerline of the spring strut.
12. A spring strut as claimed in claim 1 wherein said container
comprises a protrusion and said unrolling piston comprises a recess
which engages said protrusion when said unrolling piston is fitted
to said container.
13. A spring strut as claimed in claim 12 wherein said damping
device comprises a housing which forms said protrusion.
14. A spring strut as claimed in claim 13 further comprising axial
fixing means for axially fixing said unrolling piston on said
housing, said axial fixing means comprising said housing of said
damping device.
15. A spring strut as claimed in claim 14 further comprising a
connecting part arrange between the unrolling piston and the
damping device, said connecting part being provided with a
connection configured as a spigot extending parallel to a
centerline of the spring strut, said housing having a housing cap
with a hole which is engaged by said spigot in a snap connection,
said connecting part having at least one fastening arm which
engages the housing cap in a snap connection.
16. A spring strut as claimed in claim 14 wherein said unrolling
piston comprises an axial extension having a recess which
accommodates said housing, said axial extension extending
underneath said housing, said spring strut further comprising a
clamp which fixes said axial extension to said container underneath
said housing.
17. A spring strut as claimed in claim 14 wherein said unrolling
piston has a pair of connecting arms which encompass the housing
and are connected together by a lock screw.
18. A spring strut as claimed in claim 4 wherein the damping device
comprises a housing fixed to said container, the connecting part
having an integral housing cap which is sealed to the housing.
19. A spring strut as claimed in claim 4 wherein the damping device
comprises a housing having a housing cap with an annular recess
accommodating a seal, said connecting part having a recess which
accommodates the housing cap, said recess having an annular groove
which also accommodates said seal.
20. A spring strut as claimed in claim 19 wherein the connecting
part is seated on the unrolling piston by a push connection.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a spring strut, which has a
pneumatic spring with a spring space bounded by a U-type bellows
and an oscillation damper with a damping device which can be
modified as a function of the support pressure, the bellows riding
on an unrolling piston filled to a container of the oscillation
damper. In order to modify the damping effect as a function of the
support pressure, the spring space is pneumatically connected to
the damping device.
[0003] 2. Description of the Related Art
[0004] U.S. Pat. No. 3,399,882 and DE 44 03 196, to which U.S. Pat.
No. 5,509,512 corresponds, disclose spring struts in which the
U-type bellows is fastened on the container or the cylinder of the
oscillation damper and the U-type bellows unrolls on these
components. In these designs, the pressure in the spring space acts
on a diaphragm, which modifies the valve device or a passage cross
section by means of complicated transmission and adjustment
elements. Such spring struts are exclusively designed for
predetermined damping force variation; once determined,
modification or adjustment to the damping force can no longer be
undertaken without partial dismantling. A different damping force
characteristic demands a modification to components which are not
accessible after assembly, so that a subsequent adjustment is very
problematic and expensive.
[0005] It is also known to arrange easily accessible and variable
damping valves externally on the container of the oscillation
damper, These valves are easily accessible after removal of the
valve housing cap. Such embodiments have a hose conduit between the
spring space and the valve device, which hose conduit must be
connected both to the spring space by means of a screw connection
and to the valve device by means of a further screw connection.
These connections are not therefore only expensive to manufacture
and assemble, but are also susceptible to external damage.
SUMMARY OF THE INVENTION
[0006] The object of the present invention is to create a spring
strut with adjustment, as a function of the support pressure, of a
damping device of the oscillation damper, which spring strut has a
simple construction, can be assembled without problem, consists of
components which can be manufactured at favorable cost and
possesses a high level of operational reliability.
[0007] According to the invention, the spring space is
pneumatically connected to the damping device by a duct configured
without a hose. The duct is integrated into the spring strut and is
formed at least in part by the unrolling piston.
[0008] The invention provides a simple construction, a connection
between the spring space of the pneumatic spring and the damping
device which is protected against damage and accessible from the
outside, as well as easy and problem free assembly. The duct
section integrated in the unrolling piston is formed, for example,
by two adjacent support ribs and/or a connection hole, which open
into a further duct section. A simple connection between the spring
space and the damping device is obtained by providing the unrolling
piston with an extension exhibiting the further duct section, which
extension can be directly connected to the damping device of the
oscillation damper. The extension is preferably embodied as a
connecting part, which has a connection mouthpiece, which
accommodates a seal and which, by means of the mouthpiece, engages
in a connection hole of the unrolling piston. This creates a
connection between the spring space and the damping device which is
simple, is of favorable cost, can be assembled without problems and
is operationally extremely reliable A snap connection, between the
connection mouthpiece of the connecting part and the connection
hole of the unrolling piston, may be provided by sprung tongues
each of which has a protrusion at the end of the connection
mouthpiece and by this means engages behind the connection hole.
This creates a reliable connection by simply pressing the
connection mouthpiece into the connection hole. Such a snap
connection can be manufactured and assembled at favorable cost and
is not released by the internal pressure present in the spring
space.
[0009] A very compact design of the spring strut is created by
arranging the connecting part in a corresponding recess of the
unrolling piston and, at least in the region of the unrolling
piston, by providing the connecting part with an external surface
which is matched to the external contour of the unrolling piston,
so that the connecting part is included in the rolling surface for
the U-type bellows. By this means, a rolling surface which does not
have any interfering edges is created for the U-type bellows.
[0010] For simple connection to the damping device, the connecting
part is provided with a connection which interacts with a seal.
This connection is, for example, embodied as a spigot which forms a
plug-in connection with a corresponding hole in the housing cap. If
the center line of the spigot and the center line of the hole
extend parallel to the center line of the spring strut, it is then
also possible to produce the plug-in connection with the damping
device at the same time as the unrolling piston, which is provided
with the connecting part, is pushed onto the container of the
oscillation damper. According to a further embodiment, the spigot
forming the connection and the hole in the housing cap have a
common center line which extends at right angles to the center line
of the spring strut. In this arrangement, the connecting part can
be pushed on after the unrolling piston has been pushed onto the
container of the oscillation damper, it being also possible to
embody the trunnion pushed into the hole of the housing cap with
elastic tongues for a snap-in connection.
[0011] The accurate positioning of the unrolling piston on the
container of the oscillation damper takes place by means of one or
more radially outwardly directed protrusions on the container,
which interact with corresponding recesses in the unrolling piston.
A very simple and cost-saving embodiment is obtained if, for
accurate positioning, the housing of the damping device forms the
protrusion and the unrolling piston is in contact with this housing
by means of a correspondingly matched recess. The unrolling piston
is pressed axially downward against the housing by the pressure in
the spring space. In order to prevent any possibility of the
unrolling piston moving axially on the housing, which can occur
during transport, during installation or during operation due to
objects lying on the track, axial fixing of the unrolling piston on
the container is provided simply and at favorable cost if the
housing of the damping device is part of this axial fixing
arrangement.
[0012] Very simple axial fixing of the unrolling piston on the
container, which is produced automatically during the assembly of
the unrolling piston on the container of the oscillation damper, is
provided by a snap-in connection between these two components. This
snap-in connection is formed by at least one snap arm which engages
in a corresponding depression or recess in the housing of the
damping device, the connection feature of the connecting part being
a spigot, which extends parallel to the center line of the spring
strut and which engages in a corresponding hole in the housing
cap.
[0013] Further embodiments, which have simple and easily
manufactured fixing arrangements for the unrolling piston on the
container are created by the unrolling piston having an axial
extension, which is provided with a recess matched to the housing,
The fixing takes place by means of a clamp, which is seated on the
extension and is arranged below the housing. In a further
advantageous embodiment, the unrolling piston has two connecting
arms encompassing a cylindrical region of the housing, which
connecting arms are connected together by means of a locking screw
or a locking pin in contact with the lower edge of the housing.
[0014] A design which is simple in construction and can be
assembled without problems is obtained if the connecting part is
configured in one piece with the housing cap and is permanently
connected to the housing of the damping device. In this way, axial
fixing of the unrolling piston on the container is also
additionally created by means of the connecting part so that,
furthermore, a nicely shaped embodiment of the spring strut is
obtained.
[0015] In addition, an advantageous design is created by means of a
connecting part if this connecting part is first connected to the
housing cap of the damping device and the connection with the
unrolling piston is produced when it is pushed onto the container.
A particularly favorable embodiment is obtained if a push
connection is arranged between the connecting part and the
acceptance feature formed by the unrolling piston. Connecting parts
configured in this way can also be matched without problems to the
external contour of the unrolling piston.
[0016] The various features of novelty which characterize the
invention are pointed out with particularity in the claims annexed
to and forming a part of the disclosure. For a better understanding
of the invention, its operating advantages, and specific objects
attained by its use, reference should be had to the drawing and
descriptive matter in which there are illustrated and described
preferred embodiments of the invention.
[0017] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows a sketch, in longitudinal section, of a spring
strut according to the invention;
[0019] FIG. 2 shows an excerpt, in longitudinal section, of a
spring strut design in the region of the unrolling piston;
[0020] FIG. 3 shows a connecting part between the spring space and
the damping device, as the latter is constructed in FIG. 2;
[0021] FIG. 4 shows a further embodiment of a connection between
the spring space and the damping device;
[0022] FIG. 5 shows a further spring strut design, in which the
unrolling piston is axially fixed on the container of the
oscillation damper by means of a clamp;
[0023] FIG. 6 shows a further embodiment of the fixing of the
unrolling piston on the container of the oscillation damper;
[0024] FIG. 7 shows, in longitudinal section, an embodiment form in
which the connecting part comprises the housing cap of the damping
device;
[0025] FIG. 8 shows a view of the connecting part shown in FIG.
7;
[0026] FIG. 9 shows a view of the fixing arrangement for the
unrolling piston on the container from FIG. 6 and a connecting part
corresponding to FIG. 7.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0027] The spring strut shown in FIG. 1 includes a pneumatic spring
1 and an oscillation damper 3, a U-type bellows 5 bounding, to the
outside, a spring space 7 which is under pressure. The U-type
bellows 5 has a sealed connection on the upper end of the unrolling
piston 11 by means of a U-type bellows clamp 9. The unrolling
piston 11 is pushed onto a container 13 of the oscillation damper
3, is supported on the outer surface of the container 13 by support
ribs 21, and is sealed toward the outside by sealing rings 51. A
damping device 15 of the oscillation damper 3, which damping device
15 can be modified as a function of pressure, is arranged in a
housing 17 which is permanently connected to the container 13. The
center line of the housing 17 extends approximately at right angles
to the center line of the spring strut and acts as a stop for the
unrolling piston 11.
[0028] The pressure in the spring space 7 corresponds to the
support forces which are present between the vehicle superstructure
and the vehicle wheel and are accepted by the spring strut. In
order to achieve a modification in the damping effect of the
oscillation damper 3, which depends on the support pressure, a
pneumatic connection between the spring space 7 and a damping
device 15 is necessary. For this purpose, a connecting part 27 is
provided with a duct 25 having a connection mouthpiece 29 which
engages a corresponding connection hole of the unrolling piston 11
and a connection 33 which is inserted into a housing cap 19 of the
damping device 15. A seal 31 is used for sealing the connecting
part 27 relative to the unrolling piston 11 and a seal 35 is used
for sealing on the housing cap 19.
[0029] FIGS. 2 and 3 show details of the pneumatic connection,
sketched above, between the spring space 5 and the damping device
15. The connecting part 27 is arranged in a recess of the unrolling
piston 11. The connecting part 27 is pressed into the connection
hole 23 of the unrolling piston 11 by means of the connection
mouthpiece 29, onto which is placed a seal 31, the two components
being preferably manufactured from a suitable plastic. A snap
connection between the connection mouthpiece 29 and the connection
hole 23 is provided by spring tongues arranged at the end of the
connection mouthpiece 29. The external contour of the connecting
part 27, which is provided with the duct 25, corresponds to the
external contour of the unrolling piston 11, so that there is no
unevenness for the U-type bellows on the rolling surface. The
unrolling piston 11 provided with the connecting part 27 is now
pushed onto the container 13 of the oscillation damper 3 and is
sealed toward the outside by the seals 51. For correct positional
arrangement of the unrolling piston 11 on the container 13, the
unrolling piston 11 has an recess matched to the outer surface of
the housing 17. While the oscillation damper 3 is being pushed onto
the container 13, the connection 33, which is configured as a
spigot and carries a seal 35. The connection 33 is pushed into a
corresponding hole in the housing cap 19 and sealed, so that the
duct 25 of the spring space 5 connects to the damping device and
pressure changes occurring in the spring space 5 act on the damping
device 15.
[0030] The embodiment of FIG. 4 differs from that previously
described essentially in that the extension of the connecting part
27 overlapping the housing cap 19 is configured as a fastening arm
37. At its lower end, this fastening arm 37 carries at least one
snap hook 53 with a joint surface extending downward and a
retention surface extending at right angles to the spring strut
center line. After the unrolling piston 11 has been completely
pushed onto the container 13, this retention surface engages in the
lower edge 39 of the housing cap 19. This creates a degree of
security against unintentionally pushing the unrolling piston 11
too far up on the container 13, for example during assembly.
[0031] An additional security measure is desirable, particularly in
the case of cross-country vehicles, to prevent the unrolling piston
11 being pushed up on the container 13 by the action of objects
lying on the track such as branches or the like. FIG. 5 shows such
an additional security measure, in which the unrolling piston 11 is
provided with a downwardly directed axial extension 41 surrounding
the container 13, this axial extension 41 having a recess 43
matched to the housing 17. The extension 41 is loaded against the
container 13 by means of a clamp 45 arranged on the lower end of
the extension in a corresponding depression, it being possible for
the clamp 45 to be arranged in such a way that it is in contact
with the lower edge of the housing 17.
[0032] A further security measure to prevent the unrolling piston
11 from being pushed up on the container 13 is shown in FIG. 6. For
this purpose, the unrolling piston 11 is provided with two axially
extending connecting arms 47 on both sides of the housing 17. A
locking screw or a locking pin 49 is effective between the
connecting arms 47 and is preferably in contact with the lower edge
of the housing 17. This prevents the unrolling piston 11 being
forcefully pushed up, on the container 13, and therefore prevents
an associated loosening of the connecting part 27 from the housing
cap 19, which would also lead to a failure of the pneumatic
spring.
[0033] In a further advantageous embodiment shown in FIG. 7, the
connecting part 27 is provided with an extension, which surrounds
the essentially cylindrical outer surface of the housing cap 19 and
forms, for example, a snap-in connection with the outer surface.
The seal 35 is accommodated in an annular groove of the connecting
part 27 and is pressed against the end surface of the housing cap
19. When the unrolling piston 11 is subsequently pushed onto the
container 13, the connecting part 27 with the duct 25 is pushed
like a slide into a guide (not shown) of the unrolling piston 11.
It is possible to arrange jointing aids between the guide and the
connecting part 27, which ensure that--toward the end of the
insertion movement--the seal 31, which is placed in an annular
groove, is pressed against the sealing surface arranged in the
region of the connection hole 23. The end of the insertion movement
is reached when the unrolling piston 11 is in contact with a
contact surface on the housing 17. It is advantageous for the
connecting part 27 to be subsequently connected to the unrolling
piston 11 by means of fastening screws; this creates a security
measure against the unrolling piston 11 being pushed up.
[0034] FIG. 8 shows the connecting part 27, which is shown in
section in FIG. 7, in end view. The fastening of the connecting
part 27 on the unrolling piston 11 by means of the fastening screws
55 is likewise shown. For further axial fixing of the unrolling
piston 11 on the container 13, a retention part 57 is provided
which, after the unrolling piston 11 has been pushed on, is
fastened on the piston-rod outlet end of the container 13 and acts
on the support ribs 21.
[0035] In a further embodiment shown in FIG. 9, the unrolling
piston 11 is provided with two connecting arms 47, which surround
the housing 17 and, after the unrolling piston 11 has been pushed
onto the container 13. These arms 47 are connected by means of a
locking screw or a locking pin 49, which is in contact with the
lower edge of the housing, thus creating satisfactory fixing of the
unrolling piston 11 on the container 13.
[0036] Further embodiments, which have simple, operationally
reliable, easily assembled and low-cost connecting parts are, for
example, obtained if both the spigot introduced into the connection
hole and the connection leading to the damping device are arranged
so that they extend at right angles to the center line of the
spring strut. By this means, it is possible to ensure that the
connecting part can only take place after the assembly of the
unrolling piston on the container. The connecting part can likewise
be embodied in one part with the housing cap and be connected to
the housing by means of a screw connection.
[0037] The invention is not limited by the embodiments described
above which are presented as examples only but can be modified in
various ways within the scope of protection defied by the appended
patent claims.
[0038] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements and/or method steps which perform
substantially the same function in substantially the same way to
achieve the same results are within the scope of the invention.
Moreover, it should be recognized that structures and/or elements
and/or method steps shown and/or described in connection with any
disclosed form or embodiment of the invention may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *