U.S. patent application number 10/685716 was filed with the patent office on 2004-07-01 for muffler for air compressor.
Invention is credited to Broser, Dietmar, Woltmann, Fritz.
Application Number | 20040126247 10/685716 |
Document ID | / |
Family ID | 32038719 |
Filed Date | 2004-07-01 |
United States Patent
Application |
20040126247 |
Kind Code |
A1 |
Broser, Dietmar ; et
al. |
July 1, 2004 |
Muffler for air compressor
Abstract
For the combined intake section of a compressed-air generating
system comprising an air compressor and an air dryer, the use of an
additional muffler is proposed for an air-spring system that is
employed mainly in passenger vehicles. This muffler is installed
directly in a rubber hose leading to the atmosphere. Both air for
the air compressor is sucked in and air for regeneration of the air
dryer is discharged to the atmosphere through this muffler. The
muffler has a simple construction, because of the fact that a
damping insert, composed of a roll of noise-reducing knitted
fabric, is pushed into the rubber hose, and throttling of the air
stream is additionally provided at the point of the port to the
atmosphere.
Inventors: |
Broser, Dietmar; (Hannover,
DE) ; Woltmann, Fritz; (Lehrte, DE) |
Correspondence
Address: |
Kramer Levin Naftalis & Frankel LLP
919 Third Avenue
New York
NY
10022
US
|
Family ID: |
32038719 |
Appl. No.: |
10/685716 |
Filed: |
October 15, 2003 |
Current U.S.
Class: |
417/312 |
Current CPC
Class: |
F04B 39/0055 20130101;
F04B 41/00 20130101; F04B 39/005 20130101; B60G 2500/2012
20130101 |
Class at
Publication: |
417/312 |
International
Class: |
F04B 039/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 16, 2002 |
DE |
102 48 183.0 |
Claims
What is claimed is:
1. In an air-consuming system, said air-consuming system having a
compressed-air generating device including an air compressor, an
electric motor for powering said air compressor and an air dryer, a
pressure port for at least one of pressurizing and venting said
air-consuming system, an air inlet for sucking air from the
atmosphere, said air inlet in communication with said air
compressor and an intake device, an air outlet for discharge of
air-dryer regeneration air to atmosphere, said air outlet in
communication with said air dryer and a venting device, said intake
device including a first air line in communication with an outlet
of an air filter, a third air line extending from an inlet of said
air filter to atmosphere for passing air sucked from atmosphere
through said air filter to said outlet of said air-filter and to
said air inlet of said air compressor, said venting device
including a second air line leading from said outlet associated
with said air dryer to said outlet of said air filter and said
third air line, and a pneumatic coupling device disposed proximate
to said outlet of said air filter pneumatically connecting said
intake device and said venting device, a muffler formed as said
third air line constructed and arranged to damp sound emissions
from said compressed-air generating device.
2. The muffler of claim 1, wherein said muffler is a compact
preassembled unit, and is coupled to said air-consuming system by
at least one of slip-on joints and clamp joints.
3. The muffler of claim 1, wherein at least one of said first
air-line, said second air-line, and said third air-line is formed
by mandrel-sleeve-joint technique with a different one of said
first air-line, said second air-line, and said third air-line.
4. The muffler of claim 1, wherein said third air-line is an
elastic hose connection including an air-permeable, sound-absorbing
insulating material.
5. The muffler of claim 4, wherein said third air line includes a
throttle device adapted to narrow said third air-line in the region
between said sound-absorbing insulating material and outlet to
atmosphere.
6. The muffler of claim 4, wherein said sound-absorbing insulating
material is formed from a meshed fabric of interconnected
thermoplastic threads.
7. The muffler of claim 6, wherein said sound-absorbing insulating
material is shaped as a knitted-fabric roll.
8. In an air-consuming system, said air-consuming system having a
compressed-air generating device including an air compressor, an
electric motor for powering said air compressor and an air dryer, a
pressure port for at least one of pressurizing and venting said
air-consuming system, an air inlet for sucking air from the
atmosphere, said air inlet in communication with said air
compressor and an intake device, an air outlet for discharge of
air-dryer regeneration air to atmosphere, said air outlet in
communication with said air dryer and a venting device, said intake
device including a first air line in communication with an outlet
of an air filter, a third air line extending from an inlet of said
air filter to atmosphere for passing air sucked from atmosphere
through said air filter to said outlet of said air-filter and to
said air inlet of said air compressor, said venting device
including a second air line leading from said outlet associated
with said air dryer to said outlet of said air filter and said
third air line, and a pneumatic coupling device disposed proximate
to said outlet of said air filter pneumatically connecting said
intake device and said venting device, a multi-functional muffling
unit including said air filter and a muffler constructed and
arranged to damp sound emissions from said compressed-air
generating device.
9. The multi-functional muffling unit of claim 8, wherein said
multi-functional muffling unit is a compact preassembled unit, and
is coupled to said air-consuming system by at least one of slip-on
joints and clamp joints.
10. The multi-functional muffling unit of claim 8, wherein at least
one said first air-line, said second air-line, and said third
air-line is formed by mandrel-sleeve-joint technique with a
different one of said first air-line, said second air-line, and
said third air-line.
11. The multi-functional muffling unit of claim 8, wherein said
third air line includes a throttle device adapted to narrow said
third air-line in the region between said multi-functional unit and
outlet to atmosphere.
12. The multi-functional muffling unit of claim 8, wherein said air
filter includes an air-permeable paper filter element and said
muffler includes an air-permeable, sound-absorbing insulating
material.
13. The multi-functional muffling unit of claim 12, wherein said
sound-absorbing insulating material is formed from a meshed fabric
of interconnected thermoplastic threads.
14. The multi-functional muffling unit of claim 13, wherein said
sound-absorbing insulating material is shaped as a knitted-fabric
roll.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to a muffler and, in
particular, to a muffler for an air-spring system of the type used
in passenger vehicles.
[0002] Mufflers are used to reduce the noise output from air
compressors. FIG. 2 shows a conventional muffler, designed for a
passenger car, for the intake section (1) of a combined functional
unit comprising air compressor (15) and air dryer (16), together
with an air inlet (2) on the air compressor and an air outlet (3)
that leads to the air dryer, while functional units that form the
air-inlet path are disposed on the air inlet and functional units
that form the air-outlet path are disposed on the air outlet.
[0003] The functional units of the air-inlet and air-outlet paths
form intake section (1), which is designed as a combined intake
section as air-inlet path units are also used for the air-outlet
path.
[0004] Besides the air inlet and the air outlet, the combination of
air compressor and air dryer is provided with a pressure port (26),
by which an air-spring system installed in the passenger car is
supplied with air.
[0005] In the combined intake section (1) according to FIG. 2,
there is provided on air inlet (2) a first tubular air line (4),
which is connected to an air-line tee (10), which on the outlet
side is connected to the outlet (9) of an air filter (7), whose
inlet (8) is connected to a third tubular air line (6), which
ultimately provides the connection to the atmosphere (11); these
functional units represent the air-inlet path.
[0006] Air outlet (3) is connected via a second tubular air line
(5) to the branch of the air-line tee (10), so that air discharged
by the air outlet flows through air filter (7) and third tubular
air line (6) to the atmosphere (11). Together these functional
units form the air-outlet path.
[0007] Air filter (7) is composed of a pleated unit of
air-permeable paper filter elements, which have the ability to
retain dirt particles from the air flowing from the atmosphere (11)
to air inlet (2), thus effecting air cleaning.
[0008] In a combination of this known type comprising air
compressor (15) and air dryer (16), both intake of air at the air
inlet (2) by the air compressor (15) and discharge of air at the
air outlet (3) by the air dryer (16) take place at different times;
thus air from the air outlet (3) and air sucked in at the air inlet
(2) pass through the air filter in different directions, with the
effect of self-cleaning of the air filter. The dirt particles
retained during air-inlet flow in the air filter are discharged to
the atmosphere once again by the air-outlet air.
[0009] In addition to this function as a self-cleaning filter, the
air filter also muffles the air noises.
[0010] Air noises, which are produced during intake and especially
during venting (venting blast), are very disturbing to the
occupants of the passenger car and greatly impair their
comfort.
[0011] In the prior art, noise damping by about 3 dB(A) has been
achieved in the described manner, but this degree of reduction
cannot be regarded as entirely satisfactory. Especially in
higher-priced passenger cars, in which air-spring systems are
preferably used and which are also equipped, for example, with a
high-performance audio system, every possibility of suppressing
additional disturbing noises created by the
compressed-air-generating combination of air compressor and air
dryer must be exploited in order to improve the comfort of the
occupants.
[0012] Accordingly, it is desired to improve the muffling of a
combined intake section of an air compressor/air dryer to further
reduce noise emission.
SUMMARY OF THE INVENTION
[0013] Generally speaking, in accordance with the present
invention, a muffler is provided for reducing the noise emission of
a combined intake section of an air compressor/air dryer that
improves over prior art mufflers.
[0014] In one preferred embodiment of the present invention, a
muffler is provided for use in an air-consuming system comprising a
compressed-air generating device including an air compressor, an
electric motor for powering the air compressor and an air dryer, a
pressure port for pressurizing and venting the air consuming
system, an air inlet for sucking air from the atmosphere and an air
outlet for discharging air-dryer regenerating air to the
atmosphere. An air line connects the air filter to the atmosphere.
The muffler is constructed from an air-permeable, sound-absorbing,
meshed fabric of thermoplastic threads and is formed as the air
line.
[0015] In another embodiment of the present invention, a
multi-functional muffling unit is provided for use in the above
described air-consuming system. The multi-functional muffling unit
includes an air filtering element and a muffling element.
[0016] In yet another embodiment of the present invention, the
muffler or multi-functional muffling unit is a compact preassembled
unit that is easily coupled to the air-consuming system by use of
slip-on joints and clamp joints.
[0017] In yet another preferred embodiment of the present
invention, the air-lines of one of the previously described
air-consuming systems are formed by mandrel-sleeve-joint
technique.
[0018] Accordingly, it is an object of the present invention to
provide improved noise emission reduction in vehicles employing an
air compressor/air dryer with a combined intake section.
[0019] Another object of the present invention is to provide a
muffler that can be manufactured for very low cost while achieving
good noise-damping properties.
[0020] A further object of the present invention is to provide a
complete intake section that is constructed as a preassembled,
compact component, which can be easily connected to the unit
comprising an air compressor and an air dryer by simple slip-on and
clamp joints.
[0021] Another object of the present invention is to provide a
muffler wherein the major part of the air lines between the
elements of the intake section can be manufactured with
mandrel-sleeve joints, which are particularly cost-effective.
[0022] Still other objects and advantages of the invention will in
part be obvious and will in part be apparent from the
specification.
[0023] The present invention accordingly comprises the features of
construction, combination of elements, and arrangement of parts
which will be exemplified in the constructions hereinafter set
forth, and the scope of the invention will be indicated in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] For a fuller understanding of the invention, reference is
had to the following description taken in connection with the
accompanying drawings in which:
[0025] FIG. 1 is a schematic diagram of the combined intake section
together with the compressed-air generating system comprising an
air compressor and an air dryer according to the present
invention;
[0026] FIG. 2 is a schematic diagram of a combined intake section
according to the prior art;
[0027] FIG. 3 is a perspective view of the inventive combined
intake section;
[0028] FIGS. 4a-c depict various views of the inventive muffler
with a noise-damping insert disposed in a connecting hose;
[0029] FIGS. 5a-c illustrate how the noise-damping insert is
prepared for use; and
[0030] FIGS. 6a-b show an embodiment of the invention in which the
noise-damping insert is disposed directly in the air filter
itself.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Reference is made to the drawing figures where like
reference numerals are used for corresponding parts.
[0032] As shown in FIG. 1, compressed-air generating system (23)
comprises an air compressor (15) powered by an electric motor (14)
and operated together with an air dryer (16), such as type 899 381
29 2 of WABCO GmbH & Co. OHG, assignee of the present
application. The system (23) is intended for use in pneumatic
systems, especially for an air-spring system, for example in a
passenger car.
[0033] To inflate the air-spring bellows of the air-spring system
for the purpose of raising the vehicle chassis above the vehicle
axles, electric motor (14) is made to rotate via an electric or
electronic control unit (not illustrated), and air compressor (15)
delivers air from air inlet (2) via the dryer (16) and first check
valve (24) to pressure port (26) for the "consumer" of the
air-spring system, which strictly speaking does not consume air but
injects it into the air-spring bellows in the manner required by
the nature of the closed air-spring system.
[0034] In this process, the compressed air generated during this
air-compressor delivery phase is dried in the cartridge of air
dryer (16), in order to avoid icing of valves that may be needed in
connection with the air-spring system. During such drying in the
delivery phase, the granules of the air-dryer cartridge absorb the
moisture contained in the delivered air.
[0035] To lower the level of the vehicle chassis, the quantity of
air in the air-spring bellows is reduced, and this quantity of air
is simultaneously used for drying the cartridge granules. For this
purpose, venting solenoid valve (27) is operated by the control
unit, whereupon pressure builds up at the pneumatic switching inlet
of venting relay valve (28), thus overcoming the force of the
restoring spring and switching the valve to passing condition.
[0036] Venting from pressure port (26) takes place via the drying
path, opened venting solenoid valve (27), throttle (29), second
check valve (25), which is opened counter to its closing direction,
air dryer (16) and venting relay valve (28), which is switched to
passing condition, to air-dryer air outlet (3). Because of the
effect of throttle (29), the drying air stream through air dryer
(16) is greatly reduced, thus ensuring that regeneration of the
air-dryer cartridge takes place efficiently, while the large air
cross section of opened venting relay valve (28) ensures that the
regeneration air is passed to air outlet (3) without buildup of
dynamic pressure.
[0037] In addition, the operating point of venting relay valve (28)
can be set to various values via the indicated variable restoring
setting of the spring. Below this operating point, venting relay
valve (28) returns to its blocking state, thus preventing the
air-spring bellows from being completely vented and destroyed by
wrinkling; in this way a residual-pressure holding function is
achieved. Furthermore, a safety-valve function is obtained via the
pneumatic pilot device, which is shown as a broken line extending
from air dryer (16). This ensures that venting relay valve (28)
will open and thus prevent damage to the system if an air-pressure
safety threshold, for example of 16 bar, is exceeded during
delivery of air to air dryer (16).
[0038] All of the compressed air delivered via pressure port (26)
into the air-spring system by reinjection via pressure port (26) is
reused for regeneration of air dryer (16); in this way it is
ensured that sufficiently dried air will be ready at the
appropriate time for the air-spring system. In contrast, air-spring
systems that lower the level by releasing air from the air-spring
bellows via valves directly into the atmosphere, without passing
this air via air dryer (16), do not offer sufficient safety for
adequate air drying, making use of a compressed-air generating
system (23) of the type explained hereinabove.
[0039] A combined intake section (1) is connected to air inlet (2)
and air outlet (3) of compressed-air generating system (23). The
term "combined" means that a first air line (4) leading to air
inlet (2) is connected via trunk bore (30) and branch bore (31) of
an air-line tee (10) to a second air line (5) leading to air outlet
(3). Trunk bore (30) of the air-line tee (10) leads further to
outlet (9) of air filter (7). Thus, both the intake air to air
inlet (2) and the venting air discharged by air outlet (3) flow
through the air filter, thus cleaning the air compressed in air
compressor (15) and ensuring that the micropores of air filter (7)
are not permanently fouled by the dirt particles from the intake
air.
[0040] At inlet (8) of air filter (7) there is provided a third air
line (6), which connects air-filter inlet (8) to the atmosphere
(11).
[0041] As explained, combined intake section (1) is therefore
connected to compressed-air supply system (23), and it connects the
system to the atmosphere (11); this coupling, however, also results
in acoustic coupling between the atmosphere and surroundings and
thus between the occupants of the vehicle and compressed-air supply
system (23).
[0042] Compressed-air supply system (23) produces two kinds of
noises: air-compressor running noises and air-dryer air noises. The
running noises of the air compressor occur mainly during air
delivery, in the form of running noises in the motor bearing, in
the connecting-rod bearing and in the region of the piston ring of
the air-compressor delivery piston; a particularly important
contribution to these noises results from the point of intake from
the atmosphere (11) being directly connected acoustically to the
crankcase of air compressor (15).
[0043] The air noises caused during air drying include a whistling
sound, which occurs during air-dryer regeneration as the air,
throttled via throttle (29), escapes from the air-spring bellows to
the atmosphere (11). The main problem in addition to these
whistling noises is a very disturbing venting blast, which occurs
at the beginning of air-dryer regeneration.
[0044] During the air-compressor delivery phase, the delivery
pressure of air compressor (15) is present directly at the inlet of
air dryer (16). This can have a value of 16 bar, for example, and
so the volume of the air-dryer cartridge is filled with 16-bar air.
Because of the well-sealed effect of the overall system, this high
air pressure persists even in the time following delivery by the
air compressor. In many cases, the air-dryer cartridge volume is
still under relatively high pressure even at the beginning of
changeover of relay valve (28) for initiation of the air-dryer
regeneration process.
[0045] When venting relay valve (28) opens, the air-dryer
cartridge, which is under high pressure, is therefore suddenly
depressurized via the large free cross section of opened venting
relay valve (28), air outlet (3) and combined intake section (1)
leading to the atmosphere (11), thus producing the aforesaid highly
audible venting blast. The noise-damping measures described
hereinafter are intended in particular to damp these highly audible
regeneration venting blasts appropriately, as well as the running
noises and venting whistles described hereinabove.
[0046] According to the present invention, the third air line (6)
is itself designed as an acoustic damping device or muffler, by the
fact that a sound-absorbing insulating material (12) is installed
in this line itself; this is indicated in FIG. 1 with the
circuit-diagram symbol for a muffler.
[0047] Whereas air lines (4, 5, 10) in the combined intake section
between air filter (7) and ports (2, 3) have a single diameter (or,
in other words, nominal width, which can be 4 mm, for example, but
is matched to the air capacity of compressed-air generating system
(23)), third air line (6) preferably has a larger diameter such as,
for example, 10 mm. Whereas air lines (4, 5, 10) can also be
designed as tubular lines, for example made of plastic, third air
line (6) is intentionally designed as a flexible rubber hose; this,
in its own right, already contributes to noise reduction, because
the air molecules in the air stream are not reflected at, for
example, the surface of a plastic tube, which can be even and hard,
but impinge on the uneven and elastically compliant inside surface
of the hose, losing their energy by interaction. In FIG. 3, the
manner in which sound-absorbing insulating material (12) is
installed in third air line (6) is illustrated by means of a
partial section through third air line (6); it has the form of a
roll of knitted fabric, as shown in FIG. 5.
[0048] FIGS. 5a-c illustrate how this knitted-fabric roll (12) is
prepared. The basic material is, desirably, a hose-like gauze
produced on a circular knitting machine for thermoplastic
materials. In other words, it is desirably a knitted fabric
comprising thermoplastic threads looped together with one another.
The threads have a rectangular cross section of, for example,
0.02.times.0.08 mm, and the looping process produces meshes in a
density of, for example, 30 meshes per 100 mm of length. As
illustrated in FIG. 5a, this knitted-fabric hose is trimmed to a
length such as 90 mm in a first working step, to produce a hose
portion (17).
[0049] In a second working step, hose portion (17) is heat-sealed
along its cut surfaces (heat-sealed seams (32)), thus forming a
rectangular knitted-fabric insert (18) with a thickness of 2 to 2.5
mm (FIG. 5b).
[0050] Knitted-fabric insert (18) is then rolled up around one of
its long edges to form a knitted-fabric roll (12) (FIG. 5c). This
knitted-fabric roll (12) is finally pushed into third air line (6).
FIGS. 4a-c show pushed-in roll (12) in longitudinal section (A-A)
and cross section (C-C). The pushing-in process is simplified by
the elastic nature of the third air line (6); the connecting hose
is expanded by a suitable spreading tool, and knitted-fabric roll
(12) is then inserted into expanded third air line (6) by means of
a further tool.
[0051] By analogy to conventional mufflers containing perforated
plates, in which cross-sectional changes have a noise-damping
effect, knitted-fabric roll (12) installed in third air line (6)
achieves noise damping in the invention by the fact that the air
continuously experiences cross-sectional changes while flowing
through line (6), whereby friction effects leading to noise damping
are produced.
[0052] Besides the insertion of knitted-fabric roll (12) into third
air line (6), yet another noise-reducing measure is provided: As
best shown in FIG. 4b, third air line (6) is narrowed (e.g., to a
cross section of 6 mm) at its outlet point to the atmosphere (11),
and so a throttle (13) is formed there. This throttle causes
development of a slight dynamic pressure, thus reducing the flow
velocity in third air line (6) and in this way having an additional
noise-reducing effect.
[0053] The following table provides a representative summary of the
acoustic effect of all of the explained noise-damping measures, as
determined on a model of the inventive combined intake section (1)
in combination with the compressed-air generating system (23):
1 Individual measure Relates to Improvement Combined intake
section, lines assembled 0 dB(A) without further measures 1.
Integration of air filter (7) Prior art 3 dB(A) 2. Knitted-fabric
roll (12) in third air line (6) 13 dB(A) 3. Throttle (13) in third
air line (6) 3 dB(A) 4. Total of all measures 19 dB(A)
[0054] Compared with a combined intake section without any
noise-damping measure, connection of air filter (7), as in prior
art arrangements, achieves noise damping of about 3 dB (A).
Compared with this prior art, knitted-fabric roll (12) in third air
line (6) adds further noise damping of 13 dB (A), and throttle (13)
then reduces the noise level by a further 3 dB (A). Compared with
the prior art, therefore, noise damping totaling 16 dB (A) is
achieved with the invention, while all damping measures together
result in total noise damping of 19 dB (A).
[0055] It is noted that the explained mesh size of knitted-fabric
roll (12) is very large compared with the pore size of paper
ultra-fine filter (7); thereby the self-cleaning--explained
hereinabove--of air filter (7) by the dryer regeneration air
discharged at air outlet (3) is not impaired.
[0056] FIG. 3 shows that the combined intake section (1) can be
constructed as a compact functional unit, equipped with slip-on
pneumatic fittings, a fitting (19), coupled with first air line
(4), for insertion into port (2) of the air inlet, and a fitting
(20), coupled with the second air line (5), for insertion into port
(3) of the air outlet. These insertion processes at the
corresponding ports are indicated by dashed arrows (33 and 34) in
FIG. 3.
[0057] In third air line (6), in the region of the outlet to the
atmosphere, there is molded on a rubber double bead (35), which can
be inserted very simply into a groove-like recess in order to
fasten third air line (6). With these features, or in other words
fittings (19) and (20) as well as rubber double bead (35), a
completely preassembled intake section can be installed by being
slipped onto or clamped onto compressed-air generating system (23),
which is also preassembled.
[0058] FIG. 3 also shows a particularly cost-effective assembly of
the lines and elements of inventive combined intake section (1).
Fitting (19) is connected to first air line (4), which in turn is
connected to branch (31) of tee (10) in the form of a pneumatic
sleeve joint; in the same way, air filter (7) is connected via its
outlet (9) to trunk port (30) of tee (10), this trunk port is
connected to second air line (5), and this line is connected to
fitting (20).
[0059] In the mandrel-sleeve-joint technique, a tubular air line is
simultaneously used as a fastening means, by the fact that it is
pushed with a tool over the element to be coupled, thus forming a
pressure-tight joint. To characterize the mandrel-sleeve-joint
technique, the respective enveloping parts of a joint are shown as
"corrugated" elements (36) in FIG. 3. The mandrel-sleeve-joint
technique represents a very inexpensive connection method and it is
desirable to use the technique whenever possible, for example at
the coupling of fitting (19) with first air line (4). It should be
understood that the coupling to third air line (6) is not amenable
to this technique. Desirably, a hose clamp (37) is used instead to
secure the enveloping part of third air line (6).
[0060] Another configuration of the invention is illustrated in
FIGS. 6a,b. The sound-absorbing insulating material (12) is
repositioned from third air line (6) to air filter (7), so that
this is formed as a combined functional unit (21) comprising a
filter and a muffler. Air filter (7) is illustrated in FIG. 6a, and
functional unit (21) comprising a filter and a muffler is
illustrated in FIG. 6b.
[0061] Air filter (7) has the form of a cylindrical hollow body
provided with inlet (8) and outlet (9), (explained hereinabove)
which are molded onto a lower housing part (38) and upper housing
part (39), which were initially separate parts (38, 39). For air
filtering there is provided a first insert cartridge (40), which is
made of air-permeable paper filter elements. For installation of
air filter (7), first insert cartridge (40) of the air filter is
placed in the cavity of one of the housing parts (for example,
(38)), after which the respective other housing part ((39) in the
example) is slipped on over installed first insert cartridge (40)
and the two housing parts (38, 39) are heat-sealed to one another
by an airtight seam (49).
[0062] In functional unit (21) comprising a filter and a muffler as
shown in FIG. 6b, one of the two housing parts (38, 39), which can
have the same construction, has sufficiently enlarged overall
length--in the example of FIG. 6b, this is upper housing part
(39)--that a second cartridge (41), made of the explained
air-permeable and sound-absorbing insulating material (12), can be
provided in the cylindrical interior space of functional unit (21),
in addition to cartridge (40) which, as the first cartridge, is
disposed directly at outlet (9) of functional unit (21). The
sound-absorbing insulating material (12) of second cartridge (41)
is again desirably made of a meshed fabric of thermoplastic threads
connected to one another, and is shaped in the form of a
knitted-fabric roll; this knitted-fabric roll (12) is no longer an
elongated cylindrical body with small diameter, but instead is a
short cylindrical body with large diameter. Installation takes
place by inserting first and second cartridges (40, 41) into empty
housing parts (38, 39) and joining two housing parts (38, 39) by an
airtight heat seal (49). In this embodiment also, the
sound-absorbing insulating material (12) is disposed between first
cartridge (40) and the connection to the atmosphere (11) of third
air line (6), which is connected in the manner explained
hereinabove to inlet (8) of functional unit (21).
[0063] In the configuration of inventive combined intake section
(1) using a filter unit (21) comprising a filter and a muffler as
illustrated in FIG. 6b, third air line (6) is empty. Nevertheless,
for the reasons explained hereinabove, it is provided with throttle
(13) at the connection to atmosphere (11) in this configuration
also. The basic construction of combined intake section (1)
therefore continues to be similar to the configuration illustrated
in FIG. 3.
[0064] As an example, first cartridge (40), which is inserted in
the air filter, has a diameter of 40 mm and a length of 60 mm,
whereas second cartridge (41), which is inserted in the muffler,
has the same diameter but a length, for example, of 30 mm. By
virtue of these dimensions--which are larger than in the embodiment
according to FIG. 4--for second cartridge (41) of damping material,
second cartridge (41) can be made somewhat more simply. In
addition, insertion of this second cartridge (41) into housing (38,
39) is simplified as compared with the process of pushing elongated
knitted-fabric roll (12) into third air line (6), which is expanded
by a tool. Thus the manufacturing costs for this embodiment are
lower than that for the embodiment according to FIG. 3. A further
advantage is that more room for sound-absorbing insulating material
(12) is available in housing (38, 39) of functional unit (21) as
such than is the case in third air line (6) for sound-absorbing
insulating material (12) according to FIGS. 4a-c. Thus it may be
possible to achieve a further improvement of noise damping by
increasing the mass of damping material.
[0065] Accordingly, the present invention provides a muffler that
can be manufactured at a low cost while achieving improved noise
emission reduction over prior art mufflers. Embodiments of the
present invention may be constructed as a preassembled compact
component, which can be easily connected to an air spring
system.
[0066] It will thus be seen that the objects set forth above, among
those made apparent from the preceding description, are efficiently
attained, and since certain changes may be made in the above
constructions without departing from the spirit and scope of the
invention, it is intended that all matter contained in the above
description or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
[0067] It is also to be understood that the following claims are
intended to cover all of the generic and specific features of the
invention herein described and all statements of the scope of the
invention which, as a matter of language, might be said to fall
therebetween.
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