U.S. patent application number 09/764917 was filed with the patent office on 2001-07-26 for device for producing an overtone-rich sporty exhaust sound.
This patent application is currently assigned to Heinrich Gillet GmbH & Co. KG. Invention is credited to Bielert, Friedrich, Fuhrmann, Bernd.
Application Number | 20010009208 09/764917 |
Document ID | / |
Family ID | 7628094 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009208 |
Kind Code |
A1 |
Fuhrmann, Bernd ; et
al. |
July 26, 2001 |
Device for producing an overtone-rich sporty exhaust sound
Abstract
The device for producing an overtone-rich, sporty exhaust sound
of the exhaust system of a four-cylinder engine includes exhaust
pipes with four manifold pipes, at least one front pipe and a tail
pipe. The length and/or cross-section of at least one exhaust pipe
differ from the length and/or cross-section of the other exhaust
pipes. At least some of the exhaust pipes lead into a first, second
and/or third collecting point.
Inventors: |
Fuhrmann, Bernd; (Edenkoben,
DE) ; Bielert, Friedrich; (Gottingen, DE) |
Correspondence
Address: |
Friedrich Kueffner
Suite 1921
342 Madison Avenue
New York
NY
10173
US
|
Assignee: |
Heinrich Gillet GmbH & Co.
KG
|
Family ID: |
7628094 |
Appl. No.: |
09/764917 |
Filed: |
January 18, 2001 |
Current U.S.
Class: |
181/227 ;
181/228 |
Current CPC
Class: |
F01N 13/10 20130101;
F01N 13/08 20130101; F02B 27/04 20130101 |
Class at
Publication: |
181/227 ;
181/228 |
International
Class: |
F01N 007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2000 |
DE |
100 02 240.5 |
Claims
We claim:
1. A device for producing an overtone-rich, sporty sounding exhaust
sound in four-cylinder engines, the device comprising exhaust
gas-conducting pipes with at least four manifold pipes, at least
one front pipe and a tail pipe, wherein at least one of the exhaust
gas-conducting pipes has a length and/or cross-section different
from a length and/or cross-section of all other exhaust
gas-conducting pipes, and wherein at least some of the exhaust
gas-conducting pipes meet in a first collecting point, a second
collecting point and/or a third collecting point.
2. The device according to claim 1, wherein the length and/or
cross-section of at least one manifold pipe differs from the length
and/or cross-section of the other manifold pipes.
3. The device according to claim 1, comprising at least two front
pipes, wherein the length and/or cross-section of one front pipe is
different from the length and/or cross-section of the other front
pipe.
4. The device according to claim 3, wherein at least two manifold
pipes meet in the first or second collecting points, and wherein a
front pipe begins at the first or second collecting points.
5. The device according to claim 4, comprising two front pipes,
wherein the front pipes meet in the third collecting point, and
wherein the length and/or cross-section of one of the front pipes
differ from the length and/or cross-section of the other front
pipe.
6. The device according to claim 1, comprising a resonator space
coupled to at least one manifold pipe and/or a front pipe.
7. The device according to claim 1, comprising a screen mounted in
at least one manifold pipe and/or a front pipe.
8. The device according to claim 1, comprising a nozzle mounted in
at least one manifold pipe and/or a front pipe.
9. The device according to claim 1, comprising a valve mounted in
at least one manifold pipe and/or a front pipe.
10. The device according to claim 1, comprising a flow-active body
mounted in at least one manifold pipe and/or a front pipe.
11. The device according to claim 10, wherein the flow-active body
is a catalyst body.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a device for producing an
overtone-rich, sporty exhaust sound in four-cylinder engines.
[0003] 2. Description of the Related Art
[0004] It is known in the art that motor vehicles equipped with
six-cylinder, eight-cylinder or twelve-cylinder engines produce an
exhaust sound which is considered particularly sporty by the
customer. It is also known that motor vehicles equipped with
four-cylinder engines do not produce such a sporty exhaust sound.
Since it is not possible for reasons of cost and other reasons that
each motor vehicle is equipped with a six-cylinder, eight-cylinder
or twelve-cylinder engine, many attempts have been made to change
the exhaust system of motor vehicles with four-cylinder engines in
such a way that they produce a sportier sound. However, most of
these measures only increase the amplitude of the sound at the
outlet opening of the exhaust system at small rates of rotation and
particularly during idle operation by acoustically switching off
portions of the exhaust muffler. The exhaust sound becomes louder
as a result of these measures, however, the known and popular
exhaust sound of six-cylinder, eight-cylinder and twelve-cylinder
engines is still not achieved.
[0005] When the exhaust sound of four-cylinder engines is analyzed,
it is found that it contains the second, fourth, sixth, eighth,
etc., harmonic of the basic frequency determined by the rate of
rotation of the engine. When analyzing the exhaust sound of
six-cylinder, eight-cylinder and twelve-cylinder engines in a
similar manner, it can be found that it also contains the first,
third, fifth, seventh, etc. harmonic and, depending on the type of
engine, also the 1.5th, 2.5th, 3.5th, etc., harmonic of the basic
frequency. These harmonics produced by the higher number of
cylinders are completely lacking in the four-cylinder engine.
SUMMARY OF THE INVENTION
[0006] Therefore, it is the primary object of the present invention
to provide a device which makes it possible also in four-cylinder
engines to produce an overtone-rich, so-called sporty exhaust sound
without increasing the amplitude of the exhaust sound.
[0007] In accordance with the present invention, in an exhaust
system of a four-cylinder engine essentially composed of exhaust
gas-conducting pipes with at least four manifold pipes, at least
one front pipe and a tail pipe, the above object is met by
selecting the length and/or cross-section of at least one of the
exhaust pipes different from the length and/or cross-section of the
other exhaust pipes, wherein at least some of the exhaust pipes
lead into a first, second and/or third collecting point.
[0008] The present invention is based on the principle of delaying
the sound events produced in the four cylinders of the engine at
different times by providing different lengths and cross-sections
of the exhaust gas-conducting pipes, so that superpositions occur
at the collecting points of the pipes which correspond to a pulse
pattern as it is known from six-cylinder, eight-cylinder or
twelve-cylinder engines and, therefore, also contain the first,
third, fifth, seventh, etc. harmonic and possibly the 1.5th, 2.5th,
3.5th, etc., harmonic of the basic frequency. It has been found in
this connection that the exhaust sound subjectively even becomes
quieter because the sound energy previously only contained in the
second, fourth, sixth, etc., harmonic is transferred into the newly
produced harmonics. In addition, the transformation is achieved
equally well in the entire frequency range, as compared to previous
solutions in which it was attempted to couple the lacking harmonics
into the exhaust system by means of loudspeakers.
[0009] In accordance with a first embodiment of the invention, the
length and/or cross-section of at least one manifold pipe deviate
from the length and/or cross-section of the other manifold pipes.
This makes it possible to produce the 1.5th, 2.5th, 3.5th, etc.,
harmonics.
[0010] In accordance with another embodiment of the invention, two
front pipes are provided wherein the length and/or cross-section of
one front pipe differ from the length and/or cross-section of the
other front pipe. This makes it possible to produce the third,
fifth, seventh, etc., harmonics of the basic frequency.
[0011] In accordance with a modification of the invention, at least
two manifold pipes lead into the first collecting point where a
front pipe begins. The two other manifold pipes can be combined at
a second collecting point, as is the case in conventional
four-cylinder engines.
[0012] However, it is also possible to combine three manifold pipes
in a collecting point, wherein the front pipe following this
collecting point is combined downstream with the fourth manifold
pipe in a second collecting point.
[0013] In accordance with another embodiment of the invention, two
collecting pipes are provided which lead into the third collecting
pipe, wherein the length and/or cross-section of one of the
collecting pipes deviate from the length and/or cross-section of
the other collecting pipe.
[0014] Other possible measures for producing overtones are to
couple a resonator space to at least one manifold pipe and/or
collecting pipe, or to mount a screen, a nozzle, a valve and/or a
catalyst body into at least one manifold pipe and/or collecting
pipe.
[0015] 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, 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.
BRIEF DESCRIPTION OF THE DRAWING
[0016] In the drawing:
[0017] FIG. 1 is a schematic view of a four-cylinder engine with an
exhaust system according to the prior art;
[0018] FIG. 2 is a simplified pulse diagram of the first collecting
point II in FIG. 1;
[0019] FIG. 3 is the simplified pulse diagram at the second
collecting point III in FIG. 1;
[0020] FIG. 4 is the simplified pulse diagram at the third
collecting point IV in FIG. 1;
[0021] FIG. 5 shows the frequency spectrum corresponding to the
pulse diagram of FIG. 4;
[0022] FIG. 6 is a schematic illustration of a four-cylinder engine
with an exhaust system according to the present invention;
[0023] FIG. 7 is the pulse diagram at the first collecting point
VII of FIG. 6;
[0024] FIG. 8 is the pulse diagram at the second collecting point
VIII of FIG. 6;
[0025] FIG. 9 is the pulse diagram at the third collecting point IX
of FIG. 6; and
[0026] FIG. 10 is the frequency spectrum corresponding to the pulse
diagram of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] FIG. 1 of the drawing shows a four-cylinder internal
combustion engine 1 and an exhaust system according to the prior
art connected to the engine. The exhaust system includes four
manifold pipes 2, 3, 4, 5 which meet in pairs in the first
collecting points II and III, respectively. Two front pipes 6 lead
from these collecting points to a third collecting point IV.
Connected downstream of the collecting point IV are an exhaust
muffler 7 and a tail pipe 8.
[0028] FIG. 2 shows the simplified pulse diagram at the collecting
point II. Blotted in the diagram is the amplitude A of the pulses
produced in the cylinders 2 and 3 over the crank shaft angle
.alpha..
[0029] FIG. 3 shows in a similar diagram the pulses produced by the
cylinders 1 and 4 at the collecting point III.
[0030] FIG. 4 shows the pulse diagram at the collecting point IV at
the end of the two front pipes 6 resulting from the pulse diagrams
of FIGS. 2 and 3.
[0031] FIG. 5 shows the frequency spectrum corresponding to the
pulse diagram of FIG. 4. Shown are the second, fourth, sixth,
eighth, etc., harmonic H2, H4, H6, H8 belonging to the basic
frequency predetermined by the engine speed, wherein the amplitude
of the harmonics H2, H4, H4, H8 decreases continuously. Since the
third, fifth, seventh, etc., harmonics as well as the 1.5th, 2.5th,
3.5th, etc., harmonics are missing, the "unsporty" exhaust noise
typical for four-cylinder engines is produced at the tailpipe 8 of
the exhaust system of FIG. 1.
[0032] FIG. 6 shows the same four-cylinder engine 1, except that it
is provided with an exhaust system changed in accordance with the
present invention. In the illustrated embodiment, the four manifold
pipes 2, 3, 4, 5 are the same and also meet in collecting points II
and III, respectively. However, the front pipes 9, 10 connected
downstream of these connecting points differ from each other with
respect to length as well as cross-section. Consequently, the
pulses produced by the cylinders 2, 3 and 1, 4 travel with
different speeds through the front pipes 9, 10; this results in a
completely different pulse diagram at the collecting point IX.
[0033] FIG. 7 shows the pulse diagram at the location VII in front
of the collecting point IX. This pulse diagram corresponds to the
pulse diagram of FIG. 2, but with a time delay.
[0034] FIG. 8 shows the pulse diagram at the location VIII in front
of the collecting point IX. It can be seen that the pulses of FIG.
8 are time-delayed as compared to the pulses of FIG. 3.
[0035] FIG. 9 shows the pulse diagram resulting at the collecting
point IX. This pulse diagram differs significantly from that of
FIG. 4.
[0036] FIG. 10 shows the frequency spectrum corresponding to the
pulse diagram of FIG. 9. It can be seen that now also the first
harmonic H1, the third harmonic H3, etc., are present. It can
further be seen that the amplitude of the second harmonic H2, the
fourth harmonic H4, etc., is significantly lower because the sound
energy contained therein has been transferred into the newly formed
harmonics.
[0037] As mentioned above, it is also possible to produce the
1.5th, 2.5th, 3.5th, etc., harmonics if the length and/or
cross-section of the manifold pipes 2, 3, 4, 5 are further
varied.
[0038] While specific embodiments of the invention have been shown
and described in detail to illustrate the inventive principles, it
will be understood that the invention may be embodied otherwise
without departing from such principles.
* * * * *