U.S. patent application number 10/821999 was filed with the patent office on 2004-10-14 for air spring strut.
Invention is credited to Behmenburg, Christof, Oldenettel, Holger.
Application Number | 20040201146 10/821999 |
Document ID | / |
Family ID | 32864447 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040201146 |
Kind Code |
A1 |
Behmenburg, Christof ; et
al. |
October 14, 2004 |
Air spring strut
Abstract
An air spring strut is mounted between a chassis of a motor
vehicle and a wheel support of a wheel suspension and takes up
wheel transverse forces. The air spring strut includes: an air
spring including an outer hollow cylinder (8) and an inner hollow
cylinder (9). A piston is arranged within the inner hollow cylinder
(9) and is connected to the outer hollow cylinder (8). A first
rolling-lobe resilient member (10) is arranged between the outer
hollow cylinder (8) and the inner hollow cylinder (9) so as to seal
off an outer air chamber. A second rolling-lobe resilient member
(11) is arranged between the inner hollow cylinder (9) and the
piston (2) so as to seal off an inner air chamber (7). The inner
hollow cylinder (9) is articulately connected to the wheel support
(3). The inner hollow cylinder (9) and the outer hollow cylinder
(8) are arranged eccentrically to each other.
Inventors: |
Behmenburg, Christof;
(Lauenau, DE) ; Oldenettel, Holger; (Wedemark,
DE) |
Correspondence
Address: |
Walter Ottesen
Patent Attorney
P.O. Box 4026
Gaithersburg
MD
20885-4026
US
|
Family ID: |
32864447 |
Appl. No.: |
10/821999 |
Filed: |
April 12, 2004 |
Current U.S.
Class: |
267/64.11 |
Current CPC
Class: |
F16F 9/0472 20130101;
B60G 17/0521 20130101; F16F 9/049 20130101; B60G 2206/424 20130101;
B60G 17/0416 20130101; B60G 17/0485 20130101; B60G 2202/412
20130101; F16F 9/055 20130101; B60G 15/12 20130101; B60G 2500/2041
20130101 |
Class at
Publication: |
267/064.11 |
International
Class: |
F01B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2003 |
DE |
103 16 761.7 |
Claims
What is claimed is:
1. An air spring strut for mounting between a chassis of a motor
vehicle and a wheel support of a wheel suspension, the air spring
strut comprising: an air spring supported on said chassis and
including an outer hollow cylinder and an inner hollow cylinder
disposed at least partially within said outer hollow cylinder; a
piston arranged within said inner hollow cylinder and connected to
said outer hollow cylinder; a first rolling-lobe resilient member
arranged between said outer hollow cylinder and said inner hollow
cylinder so as to seal off an outer air chamber; a second
rolling-lobe resilient member arranged between said inner hollow
cylinder and said piston so as to seal off an inner air chamber;
said inner hollow cylinder being articulately connected to said
wheel support; and, said inner air chamber and said outer air
chamber being arranged eccentrically to each other.
2. The air spring strut of claim 1, said outer hollow cylinder
having a lower section and said lower section having a plurality of
openings formed therein; and, said inner hollow cylinder having a
plurality of struts projecting through corresponding ones of said
openings so as to be axially moveable.
3. The air spring strut of claim 2, said piston being connected to
said lower section of said outer hollow cylinder in a region of
said lower section disposed between said openings viewed in a
radial direction.
4. The air spring strut of claim 3, wherein said air spring has a
longitudinal extension and said openings are axially parallel to
the longitudinal extension of said air spring.
5. The air spring strut of claim 1, said inner and outer air
chambers conjointly defining an interface; and, passage means
disposed at said interface for permitting an air flow between said
air chambers.
6. The air spring strut of claim 5, wherein said passage means
comprises valve means mounted at said interface.
7. The air spring strut of claim 5, wherein said passage means
comprises at least one bore formed at said interface through which
said air chambers communicate with each other to permit said air
flow therebetween.
8. The air spring strut of claim 1, wherein said piston is
configured as a shock absorber.
9. The air spring strut of claim 1, further comprising spring means
for taking up impact loads including a maximum load when the air
spring strut bottoms; and, said spring means being disposed at
least at one of the following locations: said chassis; the upper
end of said outer hollow cylinder; and, at the outer end of said
piston.
10. The air spring strut of claim 9, wherein said spring means is
made of a spring elastic material.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority of German patent
application no. 103 16 761.7, filed Apr. 10, 2003, the entire
content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Air spring struts for motor vehicles have been known for
some time in various embodiments. These air spring struts
essentially include a piston element which is articulately
connected at one end to an inner wheel support of the wheel
suspension of the motor vehicle and is supported at the other end
on the chassis of the motor vehicle via an air spring.
[0003] The air spring itself can be formed by a one-chamber system
or a multi-chamber system. So-called rolling-lobe resilient members
of the air spring are supported on the outer contour (wall) of a
roll-off piston.
[0004] One-chamber systems are, for example, disclosed in German
patent publications 3,624,296 and 4,213,676. During operation, a
roll-off piston moves within the rolling-lobe resilient member of
the air spring. This rolling-lobe resilient member folds over upon
itself and forms the rolling lobe which, in turn, rolls off over
the outer contour of the roll-off piston.
[0005] Multi-chamber systems have been proven for obtaining a
highest possible spring action or damping. A two-chamber system is
known from German patent publication 2,406,835 wherein the air
space, which is available, is formed by two separate air chambers
which, however, are connected via throttle elements such as
valves.
[0006] U.S. Pat. No. 5,180,145 discloses a multi-chamber system
which includes an outer rolling-lobe resilient member and an inner
rolling-lobe resilient member. The rolling-lobe resilient members
are either directed in the same direction or are directed toward
each other and roll off on roll-off pistons.
[0007] The above solutions relate to multi-chamber systems of air
springs and are complex in their construction and with respect to
their manufacture. In addition, these multi-chamber systems are
relatively large which has been shown to be disadvantageous because
of the tight conditions in the region of the wheel axles.
[0008] Furthermore, wheel contact transverse forces, which act on
air spring struts, have been shown in practice to be especially
disadvantageous for the support of the air spring strut as well as
for the air springs thereof and these transverse forces are
countered especially by the more compact configuration of the air
spring struts.
[0009] A one-chamber system is suggested in German patent
publication 3,624,296 for compensating the wheel contact transverse
forces. In this system, the transverse forces, which counter the
above-mentioned wheel contact transverse forces, are generated in
such a manner that the rolling-lobe resilient member is supported
on a shield. With this measure, an expansion of the rolling-lobe
resilient member is countered in the direction of the transverse
forces which are disadvantageous. The shield encloses the
rolling-lobe flexible member in its peripheral region up to
180.degree., preferably, however, 90.degree..
[0010] This solution can bring satisfactory results for one-chamber
systems. With respect to multi-chamber systems, these are built
longer in comparison whereby considerably higher forces act on the
air spring or its support. It is from this point that the invention
proceeds.
SUMMARY OF THE INVENTION
[0011] It is an object of the invention to provide an improved air
spring strut having an air spring which is of the two-chamber
system type and which is easy and cost effective to manufacture. It
is a further object of the invention to provide such an improved
air spring strut which has a lesser structural height than
conventional air spring struts. In addition, the air spring strut
of the invention exhibits a high transverse stiffness and
effectively counters the disadvantageous wheel contact transverse
forces.
[0012] The air spring strut of the invention is for mounting
between a chassis of a motor vehicle and a wheel support of a wheel
suspension. The air spring strut includes: an air spring supported
on the chassis and including an outer hollow cylinder and an inner
hollow cylinder disposed at least partially within the outer hollow
cylinder; a piston arranged within the inner hollow cylinder and
connected to the outer hollow cylinder; a first rolling-lobe
resilient member arranged between the outer hollow cylinder and the
inner hollow cylinder so as to seal off an outer air chamber; a
second rolling-lobe resilient member arranged between the inner
hollow cylinder and the piston so as to seal off an inner air
chamber; the inner hollow cylinder being articulately connected to
the wheel support; and, the inner air chamber and the outer air
chamber being arranged eccentrically to each other.
[0013] With the above solution, an air spring strut is provided
which, in an especially advantageous manner, combines a good spring
action and/or damping from the multi-chamber system with an
effective transverse stiffness. With the eccentric arrangement of
the two air springs to each other, disturbing wheel contact
transverse forces can be countered in a defined manner whereby an
improved driving performance and a longer service life results for
an air spring strut configured in this manner.
[0014] A further advantage is that the air spring strut is built
relatively short because of the guidance of the two hollow
cylinders within each other and, accordingly, less structural space
is needed than would be needed for conventional air spring struts
having multi-chamber systems.
[0015] In a preferred embodiment of the air spring, the outer
hollow cylinder has a lower section having openings through which
struts of the inner hollow cylinder project so as to be axially
moveable. In addition, it is advantageous when the piston element
is connected to the lower section of the outer hollow cylinder in a
region which is located between the above-mentioned openings viewed
radially. With this configuration, the air spring is configured to
be especially compact.
[0016] Although the openings in the lower section of the outer
hollow cylinder can be virtually aligned as desired, it is
preferable when these openings are arranged axially parallel to the
longitudinal extension of the air spring.
[0017] In one embodiment of the invention, the two air chambers are
connected to each other via bores and/or valves to permit flow
therebetween in order to realize a ventilation of the air volume
between the two air chambers.
[0018] Furthermore, at least one spring element is arranged on the
chassis of the motor vehicle and/or on the upper end of the outer
hollow cylinder and/or on the upper end of the piston element to
take up impact forces or to take up the maximum force when the air
spring strut bottoms. It is practical that these spring elements
are made of spring-elastic material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention will now be described with reference to the
drawings wherein:
[0020] FIG. 1 shows the wheel suspension of a motor vehicle having
an air spring strut according to the invention; and,
[0021] FIG. 2 shows a section view of the air spring strut taken
along line I-I of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0022] FIG. 1 shows a wheel 15 which is supported on the chassis 5
of a motor vehicle by a wheel support 3 and an air spring strut
having an air spring 1. In addition, a control link 4 is
articulately connected to the wheel support 3.
[0023] The air spring 1 is configured as a two-chamber air spring
wherein two hollow cylinders (8, 9) are arranged so as to be
axially displaceable one into the other. The outer one of the two
air spring chambers (6, 7) is defined by the inner wall of the
outer hollow cylinder 8 and the outer wall of the inner hollow
cylinder 9. These inner and outer walls are axially displaceably
connected to each other and sealed via an elastic rolling-lobe
resilient member 10.
[0024] Furthermore, the outer hollow cylinder 8 has a lower section
16 having openings 17 through which struts 18 of the inner hollow
cylinder 9 are guided so as to be displaceable in the longitudinal
direction. The lower section 16 is, in addition, connected to a
piston element 2 which projects into the upper section of the inner
hollow cylinder 9. The outer wall of this piston element 2 together
with the inner wall of the upper section of the inner hollow
cylinder 9 define a second, inner air chamber 7. The piston element
2 and the inner hollow cylinder 9 are connected to each other so as
to be axially displaceable with respect to each other by a
rolling-lobe resilient member 11 which seals the above-mentioned
walls.
[0025] To ensure a ventilation of the air volumes between the outer
and inner air chambers (6, 7), these chambers (6, 7) are connected
to each other via bores and/or valves 12 so as to permit the flow
of air therebetween.
[0026] As shown in FIG. 1, the inner hollow cylinder 9 is so
arranged axially displaceable in the outer hollow cylinder 8 that
the inner hollow cylinder 9 extends into the rolling-lobe flexible
member 10 of the outer hollow cylinder 8 when the air spring 1
deflects. In this way, a rolling-lobe is configured with which the
rolling-lobe resilient member rolls off between the wall of the
outer hollow cylinder 8 and the wall of the inner hollow cylinder
9.
[0027] In the same manner, the piston element 2 extends into the
rolling-lobe resilient member 11 of the inner hollow cylinder 9
whereby a rolling lobe is likewise formed with which the
rolling-lobe flexible member 11 rolls off between the wall of the
inner hollow cylinder 9 and the wall of the piston element 2.
[0028] The diameter d.sub.2 of the inner hollow cylinder 9 is
selected to be less than the diameter d.sub.1 of the outer hollow
cylinder 8 in such a manner that, on the one hand, the inner hollow
cylinder 9 can be axially moveable in the outer hollow cylinder 8
and, on the other hand, an unhindered roll off of the rolling lobe
is ensured with a correspondingly high support thereof between the
two walls. The same is true between the inner hollow cylinder 9 and
the piston element 2 and, for an eccentric arrangement of the two
hollow cylinders (8, 9), it is important that they can move
relative to each other.
[0029] A high transverse stiffness of the entire system is ensured
already because of the radial support of both rolling-lobe
resilient members (10, 11) in all directions. This support is
significantly improved in that the two air chambers (6, 7) or the
hollow cylinders (8, 9) are not arranged coaxially but are instead
arranged eccentrically to each other as shown in FIG. 2.
[0030] With this measure, and as shown above, disturbing
wheel-contact transverse forces can be advantageously countered in
that a suitable transverse force, which counters the wheel-contact
transverse force, is generated on the piston element 2.
[0031] The countering transverse force can be adjusted within
defined limits by the selection of the eccentricity E shown in FIG.
2, that is, with the selection of the offset of the longitudinal
axes of the two hollow cylinders (8, 9) to each other.
[0032] The piston element 2 is shown as a solid piston. However, in
lieu of a solid piston, a known shock absorber can be used whereby
a so-called spring damping unit is formed which, in turn, exhibits
an especially favorable spring and damping characteristics.
[0033] As shown in FIG. 1, a spring element 13 is mounted on the
motor vehicle chassis 5 and a spring element 14 is mounted on the
piston element 2. These spring elements (13, 14) are preferably
made of a spring-elastic material. Maximal impact forces or maximal
forces which occur when the air spring strut bottoms can be taken
up by the spring elements (13, 14).
[0034] It is understood that the foregoing description is that of
the preferred embodiments of the invention and that various changes
and modifications may be made thereto without departing from the
spirit and scope of the invention as defined in the appended
claims.
* * * * *