DE2116888A1 - silencer - Google Patents

Description

Or. Ing. H. g

DJpL Ing.H. Houck Dipt Fhys. W. Schmitz Mt23

Tel. 538ßS8S

Michael W. Freeman

401 David Whitney Building 3 April 1971

Detroit, Michigan 48226, USA Attorney File M-I546

silencer

The invention relates to a sound and resonance damper for systems in which gases under fluctuating temperature, pressure and speed conditions must be dissipated.

Silencers, for example mufflers for exhaust systems from. Power machines and the like are, for example, in IJS-PSs 3,354,986, »8,629, 3,306,393, 3,315,761, 3,329,237 and 2,274,599 or in the" Handbook of Noise Control "by CMHarris, paragraphs I8-7 ,. 18-8 and 31-16 to 20. Although the measures described in these and other publications are generally able to dampen or eliminate the formation of noise to a certain extent, they are not able to control the formation of resonances with changing frequencies or to improve the useful performance of the engine or the like. _;

According to the invention, a device for monitoring the generation of noise and in particular a muffler for internal combustion engines

1098A3 / 1298

- S'3sSGhatfen iserden ,. aera can influence the noise and acoustic emissions in sifrdeSsastellender tit and achieve improved useful - laistöngen. In particular, the inventive. A moderate silencer should be able to largely attenuate resonance signals at certain frequencies and to keep noise generation and exhaust resistance extremely small =

The control device according to the invention is capable of the explosion of oasis mixtures of high speed and increased temperature ψ and arfeöfiten pressure, for example different from exhaust gases !? Power machines, such as internal combustion engines, tubular industrial equipment, firearms or the like, to dampen or switch off. If the gas is fed to the concave end of a coiled insert of the silencer according to the invention. The insert is a cast part or consists of a strip coiled into several coiled cones; The angle of inclination of the lateral surfaces of the helical cone lies along the axis of the helical insert and the distance between

k see the base and the apex of each cone within prior t

bener limits ^ and the respective truncated cone, which xtfird * is formed by a spatially designed, coiled cone, has dimensions within a given size range

Ifeit-ere advantages and characteristics of the. Invention emerge from the claim and the following., For example !! Bescteaibuiig in ¥ © r-Miidmis with. the drawings. Is shows ι

109843 / 12-98

I shows a partially sectioned side view of a silencer designed according to the invention,

1a shows a section of a further exemplary embodiment according to the invention with spiral shaped cones, and

Fig. 2 is a schematic representation of a spirally rolled Sheet metal insert.

Due to the special design of the noise control device, for example the muffler for internal combustion engines, the generation of noise can be reduced considerably, the formation of resonances can be eliminated and the performance of the engine can be improved by reducing the back pressure to an optimally low value and using the exhaust gases to improve the operating behavior of the engine These advantageous effects are achieved together by regulating the direction of flow of the exhaust gases that flow from the engine or a similar device at elevated temperature and pressure at high speed through the silencer according to the invention, in which a number of helical cones in the silencer housing is arranged, which are formed by a wound or cast insert with a helical or spiral cone shape, and the outer surfaces of the cones inclined within predetermined angular ranges are employed as well as the distances Each K @ gelstumpfes or any geometric * spatially formed conical insert piece, the diameter üer base of each cone, and the ratio of the distance of the cone formed

-4-10S843 / 129S

blunt to the diameter of the base of the cone each lie within specific limits so that the advantages of the invention are err@ie.ht = In the silencer according to the invention, as shown in Fig. d _Q the

of the silencer, d ^ the envelope diameter of the outlet opening. "of the Keg @ is, ρ the distance between the spirals ^: and 0 that between the spirals and the center line of the silencer;

ddd - £ > _ £ »■ _J 1 d, ρ

are the dimensions of the silencer ο, ο, ο and ^:

0 within the following size rangesί

should be between 0.015 "and 0.7, · should be between ao and 2j

__o should be between 5 and 0.5j and P.

0 should be between 90 and 20 °.

However, these parameters do not mean that the values d ^, ρ and 0 are constant; rather, they can be variable within a considered silencer. Therefore, if the volume of the gas to be damped increases, the above parameters are influenced by considering the laminar flow.

yes yes -

meters ^ _- O and __o approach the lower values given above

¹ A

_J2 approaches the upper value and 0 decreases. this

does not mean, however, that the values of p, 0 and cL cannot fluctuate within one and the same silencer. The angle 0 is preferably between approximately 20 and 65 ° with respect to the axis of the coiled insert and that indicated by "1 ^M in the figures

1-098-43 / 1 296

-V- ~ 21T6W8

distance shown between each converted cone (truncated cone); between about 15 to over 120 cm. Table 1 shows under chi ed -j borrowed values of the ratios given above?

Table 1 "

^ά ο

1 2 8th 12th 12th 12th 0.083 0.166 0.666 1 2 8th 24 24 24 0.0415 0.083 0.333 * 1 2 8th 36 36 36 0.0278 0.0555 0.222 1 2 8th 48 48 48 0.0208 O, o4l5 0.1666 1 2 8th 60 60 60 0.0166 0.0333 0.1333 1 2 8th 72 72 72 0.01385 * 0.0278 0.111

ο can even be smaller than "0" of casein » The largest d. can ΐ

^d i!

greater than half of d _Q until equal to 2. Thus, j

I these limit values fluctuate within a wide range. i

* The lower value can be so low that d _Q equals 0.01385, |

and the upper value can be so high that ο equals 0.666 or j

■ ■ '~ T!

0.7 is.

In general, the distance ρ can be along the silencer change so that the exhaust gases optimally flow through the muffler. and by eliminating noise a maximum under the formation of resonance is suppressed. Sine more, in the

. ■ ■ ■ -6-

1Q9843 / 12S6

Fijpj? Sa §t? G> r aight shown effective © 'measure © is the inöe ^ usig ü @ s lustrlttsöiirefeisessers individual fluted cones or Kegslgroup © n in the same silencer, whereby a further noise reduction is achieved and a disturbing noise generation is suppressed becomes "" whereby such a change in the outlet diameter d. in the cones allows a further reduction in the exhaust resistance or back pressure to be achieved.

To prevent the Resonansbildung or to provide for Geräuseiibsseitigong and keep the back pressure as low as possible, should also following Abwandlungsraöglichkelten werdenι considered the first change of the cone opening angle 0 in FIG. 1/2 = 'Sn <?. @ Tion of Äustrifetsdurchmessers d . also enables the reduction of the Ssgendrucksi 3. Change of the Äbstanäes pi 4 »indexing of the truncated cone diameter to the distance ρ and to the length ratio of the main damper d _o / i; 5. Perforation or schallscbluckea- 'ß®F formation of some of the coiled cones towards the end of the sound = - towards.

lig- I ₃ the one according to the invention designed muffler ge contains the muffler a housing 10 with frontal Yersöhlußplatten 11 and 12. As indicated by the arrow, is oils ferschlußplatte.12 at the inlet end of the Sehall-

e! iüspf © Fs and is provided with an inlet 1J> through which the "Abg & s ust @ F Bridge ™ and speed conditions into the interior öas GehSu s © s 10 g @ Iang @ nj- the inlet IJ is surrounded by a plan view 1.4 ^ to be connected to the exhaust pipe of an engine

109 8 43/1296. "'

* 5 it

from a suitable Bieclistanzfeeii or as a cast part. The F3.ä'2lien of the spiraled © ** cones can also be covered with sines »MaterialschiGiiö, in the chemically active® materials © of the Eats lysato ^ sn are housed * the oils change gases during installation.

The Vs ^ sole plate 11 is also surrounded by a flange 16 with an outlet opening of the oil, which is required . if necessary, can be connected to an exhaust port. öemäS the figures, the sintering and AuslaBöffnungen are indeed centered mm GahÜus®,

angecrdr »et-. _t can also be arranged, if desired, axssntiisch ^Jeöoch:

A substantially helical guide plate 1? Is located in the housing. Bite baffle plate is produced by using a strip of a suitable material * for example a metal fcfelfgsi? is rotated in an essentially helical path, so that the quartz surface of the strip runs at a predetermined angle 0 between 20 and 6.5 ° to the axis of the helical sine law and the "truncated cone" of each screw thread or cone has a limited distance ρ.

The exposed inner edge of the guide plate can be folded over * "Doubling up or being otherwise reinforced. I

Is the inclination of the transverse surfaces of the strip upstream I gugswelse so large that it with the axis of gewenäeltea insert an angle of between 20 ° tool- and process monitoring 65> 5ilö.en _s as indicated by the angle?; * 0 in Fig. 1 is inclined.

-8-108843 / 1298

.! ■; "■■■" ■ "■" ■■ "■ .." "■■" - 8 - ■■. ■■■ 2116889

The distance between adjacent spirals or helical threads ρ should be chosen with regard to the inclination of the transverse surfaces 0 such that adjacent spiral or helically coiled surfaces overlap in planes which are perpendicular to the axis of the coiled installation, as clearly from Fig »1 can be seen. The diameter of the cone d _Q and the ratio 0: p should also be within specified dimensional limits in order to obtain noise and resonance control. .

While the special design of the coiled guide plate from ^! the particular pressure and speed conditions depend to the '■ _ regulating gas, the tendency of adjacent coils preferably changes from one to the other end of the guide plate ;. When high pressures occur, the coiled guide plate receives a; steeper starting angle 0 and the slope decreases gradually or in stages. Thus, the first coil should be arranged so that its transverse surface is at a greater angle to the axis of the coiled insert than the subsequent coils. At low pressure conditions, the coiled surfaces initially have a less steep angle of inclination 0, with the subsequent coils running at even smaller angles. The device can follow a helix stepwise or precisely, and silencers constructed in this way have shown excellent results when tested under operating conditions. The angle of inclination, opening or rise angle can be changed if desired, but such changes can be dispensed with in the silencer according to the invention.

109843/1286

- 9 - 2T168W

The silencer according to the invention can be made of any suitable Material and by any suitable means by which inside the housing of the muffler of the helical or spiral-like conical installation is achieved within the dimensional limits described above - the helical-cone shape can basically correspond to the shape of an empirically established logarithmic spiral, which is mathematically divided by the Formula can be represented:

(I)

where χ is an integer between 1 and 12, preferably between 5 and 7i A and & - a unit of measurement and a constant, $ * is the vector and e is the base of the natural logarithm.

A muffler for an engine was used to test the invention manufactured whose internals were formed by endless helical cones within the construction limits given above- i those that corresponded to the course of an empirically determined logarithmic spiral, as represented by the above formula (I) is. The internal fittings of the sound absorber were replaced by end + loose cones formed of spiral shape. Around these cones with un-

To produce different angles of inclination, opening or rise and heights, strips were made from a metal sheet of the size 2k j or 26 in accordance with the shape of the empirical logarithmic, mixed spiral of the mathematical formula (I). In the case of one silencer, χ = 5, in the case of another equal to 5 * 5 »Del, another equal to 6 and in the case of another equal to 6.5.

, -ιο

ί 09843/120 6

2116880

θ was -between '0 and 900 °. The unit of measurement for C * · became inches (2 * 5 ^ ο ©) selected. In the formula, A and OC were chosen to be constant, and e was the base of the natural logarithm. ^ represents the .Vector. Figure 2 shows the correspondingly formed metal

Ifcleehteil IS.

Each strip of metal was rolled, making it a multilayered one continuous truncated cone manufactured. In some cases, the Cone rolled from the inside, i.e. with% = 0, in others Cases the cone was from the point where Q = 900 ° is rolled. In each case the successive cones had different slopes. In the first case there were cones, which were shorter at the beginning of the series of consecutive cones and had a steeper slope. The corresponding silencer offered more resistance to the exhaust gases and created one slightly larger counter pressure. In the second case, there were cones in which the series of consecutive cones with cones larger Altitude and lesser inclination began, the inclination fluctuating between 15 and 35 degrees. In this case the size of the unthrottled middle outlet opening about 1/64 to 1/3 of the total diameter of the guide plate «The correspondingly designed silencer offered the exhaust gases a lower flow resistance and had a very low back pressure, for example at 90 km / h

ο P

about 0.035 kg / cm and at 120 kmh about 0.12 kg / cm, which is a considerable improvement compared to conventional silencers ^! tes result is. A spoke hub suitable for the silencer i

Each made from a metal strip of about 0.8 to 1.2 cm * can be put into the prefabricated cylinders of about 12.5cm

I ■ .. "■" ■ -ri-

1098437129 6

or-be inserted directly into the ikuslaßleiturg * The. 3Ce gal "blunt can be bent apart so that you can see loose cone-shaped sections * They are designed in such a way that the base is a cone within the base and the following cone and the" truncated cone "lies within each Kegel's ito-ariiaito - # or - »- given dimensional limits is kept at a distance. This sails can be inserted into the spoke hub, and each icosus can be welded, screwed, crimped or the like to the sides of the spoke hub.

The finished spoke hub with the cones welded to it can then be inserted into the corresponding cylindrical housing. The sidewalls of the spoke hub of each assembly can be welded to the sides of the corresponding cylinder »

The corresponding cylinders can be sealed at both ends, for example by viewing the_Versehlußpäatten, where ' at each end connection pipes with a diameter of 5 cm at the Inside of the outlet end and a diameter of 4.5 cm to be attached to the inside of the inlet end.

These silencers, which are located in the manner described above in differentiate between the selection of different values of χ in the formula, were installed one after the other and their operating behavior became is monitored for a period of time under actual operating conditions. Under the present Yersuehfos conditions it was shown that the Exhaust where χ = 5 * 5 had the best operating behavior *

■ -12-

108 843/1296

■ "--.. --- ..- ■ _ ₁₂ _; -: ■ -2ΤΊ6Ϋ88

however, all of the mufflers worked satisfactorily and were far superior to the conventional mufflers. This
The value of χ was the most favorable for the engine under consideration and is of course only a numerical example. Power machines differ considerably in terms of their structure and their operating,

wisely, and in any case, "therefore the exhaust is preferably shown in FIG Designed in accordance with the operating conditions that occur .;

The design changing for different operating conditions j conditions refers not only to the design of ^Blechstanz-: partly, as described above, but also on the relevant Building [Liehe training of the muffler, gung including its interpretation · example in terms of Inclination of the guide plate, des
The distance between the coils and the relative size of the openings at the vertices of the cones, if such openings are present. Probably not achieved ob \ a single exhaust in all cases the best i results, to exhaust the invention are suitable but for a wider operating range than the herkömmli chen silencer. Also, the value of χ and the constants A and QC can have widely varying positive values, and accordingly attempts have been made with χ between 1 and 12.

The effectiveness of the device according to the invention as a silencer depends on the change in dimensions, so that the
Frequency spectrum of the sound suppression the optimal range
is approximated. By changing the outer diameter of the changed cone of a considered silencer, that is, through
Formation of the silencer housing as a truncated cone and not
ale cylinder, can be combined with the distance between the coils. ■

^: " - ■■ - ■ - ■;" 15. - - """2,888

an uninterrupted continuous sequence of acoustic chambers in the exhaust create different dimensions and volumes, so that each chamber is tuned so that they make noises a given sequence section is suppressed and overall the on; most disturbing noises are muffled. The dimensions of the acoustic chambers are determined empirically and can be adapted to the particular assigned engine or the operating state of the;

i power machine to be tuned. j

Resonance formation at an appropriate frequency usually occurs with silencers, and with the device according to the invention such a resonance formation can be switched off in various ways. First of all, the section of the muffler, from which the resonance emanates, easily through listening devices, e.g.

wisely with the help of an ordinary stethoscope. The |

The source of resonance can optionally also be determined by attaching a rod to ^: the exhaust pipe, shifting the rod along the exhaust pipe and determining the point at which. the resonance

kung can be heard the loudest. ]

The suppression of the resonance formation can be achieved! that the flow pattern of the exhaust gas flow at or near the point of origin of the resonance is broken. A simple measure is to cut the exhaust pipe at the point of origin of the resonance and then to turn one section of the exhaust over with respect to the other and to close the two sections together ·; associate. Another measure to suppress the formation of resonance is to arrange ^ partition walls in the silencer!

10984 3/1296

■ 9

• to arrange permeable sieves at the lesonanz exit point * the deform conical coiled guide plate by making them uneven is rotated> openings at the resonance point, for example Holes in the cylindrical wall under the housing

; to train or facilities to prevent vibration and for the acoustic absorption of the guide plate

* "watch" - '.

' The silencer according to the invention does work by itself in challenging the exhaust gases. The work performance corresponds in some respects to the Bernoulli theory, apart from the fact that in this pail the pressure and the velocity of the exhaust gases provide the energy for this work. Since this variable can be optimized, the back pressure and the resonance can be regulated by given building regulations.

According to the invention designed visual silencers have been carefully tested in terms of their working and operation, and it has been found that they are superior to conventional silencers *, both in terms of the sound attenuation of the exhaust system of the engine and in terms of the overall efficiency of the engine. The back pressure of the silencer according to the invention is relatively smaller. In addition, silencers according to the invention can be manufactured in an endless construction at relatively low costs. Their installation in motor vehicles is extremely easy, as they can be installed in the same way as conventional Kusl & Bvohre or inserted into the exhaust pipe. The silencers can be designed to be flexible and dera-

to that required for installation in the vehicle

Fona be bent.

109843/1296

Claims (1)

PatontanwäKo Dr. Ing. H. Neg & ndank DIpI. Ing-H. Haudc Dlpl.Phys.W.Schmifc SM * nehait15, Mox «rttfr.23 Michael W. Freeman 2 Π 68BB David Whitney Building April 3rd 1971 Detrdfc, Michigan 48226, USA Attorney File M-1546 Claims Silencer with an elongated tubular housing »through ■ - j the exhaust gases flow from a housing inlet to a housing outlet at high speed at increased temperature and increased bridge, characterized in that a coiled, conical installation (17) with an opening angle (0) between 2o and 9o is arranged in the housing is, the one ^; Spiral flow path for the exhaust gases forms that the distances between the respective coiled cone in a predetermined
Size range, and that the ratio (^ ₀ /!) Of the cone diameter to the length of the silencer in the range between 0.015 and 0.7 * the ratio (d ^ d.) Of the cone diameter ⁰ ^ ^x and
to the outlet opening between infinity / 2 and the ratio (d / p) of the cone diameter to the distance between the coils is between ₍ 5 and 0.5. " 2. silencer he according to claim 1, characterized by its use ■ dung as an exhaust pot, where the ratio of the cone diameter rej ■ ', ■■■■' \ to the distance between the coils is between 2 and 0.5 and resonance ¹ 109843/1296. « phenomena are prevented and work is done by the exhaust gases will.. j5. Silencer according to claim 2, characterized in that the muffler is assigned to an internal combustion engine and several _v : 'spiraled' cone, whose • respective opening angle from Housing inlet (IJ) to outlet. (15) increases steadily., A. Silencer according to claim 2, characterized in that the ■ Muffler is assigned to an internal combustion engine, and several ' has coiled cones, the respective opening angle of the! Housing inlet (13) to outlet (I5) steadily decreases. 5. Silencer according to claim 3 or 4j, characterized in that. ^: that the coiled installation (17) is perforated. . 6. Silencer according to one. Claims 3 to 5 * thereby marked / shows that the coiled cones are shifted to one another. , 7v silencer according to one of the preceding claims, marked ; characterized by the arrangement of curved deflection plates. OS843 / 129 6