COMBINED EXHAUST GAS SILENCER

Abstract

A combined exhaust gas noise silencer consisting of a system of hollow elements with a mutual housing comprising a front face of the silencer connected to the supply pipe of exhaust gases, and a rear face of the silencer with an outlet from the rear face of the silencer, where the originalinlet exhaust gas (?.sub.p) carrying a noise wave is divided into at least two flowsan exhaust gas flow (?.sub.z) carrying a shifted noise wave with delayed wave length, and an exhaust gas flow (?.sub.n) carrying a non-shifted noise wave, which are subsequently combined into a common exhaust gas flow (?.sub.s).

Claims

1. Combined exhaust gas noise silencer consisting of a system of hollow elements with a mutual housing (1) comprising a front face (3) of the silencer connected to the exhaust gas supply pipe (2) a rear face (17) of the silencer with an outlet (18) from the rear face of the silencer and chambers divided by transverse partitions, where the original inlet exhaust gas (?.sub.p) carrying a noise wave is divided into at least two flows: an exhaust gas flow (?.sub.z) carrying a shifted noise wave with delayed wave length, and an exhaust gas flow (?.sub.n) carrying a non-shifted noise wave, which are subsequently combined into a common exhaust gas flow (?.sub.s), where the system of hollow elements contains an inlet expansion chamber (5), connected to located between the front face (3) of the silencer and the inlet transverse partition (6), and the common outlet expansion and mixing chamber (16) located between the outlet transverse partition (15) and the rear face (17) of the silencer, wherein between the inlet transverse partition (6) and the outlet transverse partition (15) one or more inner expansion chambers (8) of the non-delayed flow are arranged in the direction of the noise wave passage, having an inlet opening (7) of the inner chamber in the inlet transverse partitions (6) and having inlet openings (19) of the common outlet expansion and mixing chamber (16) in the outlet transverse partition (15), and in parallel to that inner expansion chamber/s (8) of non-delayed flow 4n+2, inner expansion chambers (12, 14) of the delayed flow are arranged sequentially in the direction of the noise wave passage, with the inlet openings (7) of the inner chambers (12, 14) of the delayed flow in the transverse partitions (6, 13) on their inlet, where n is 0 or positive integer number, and where each of the inner expansion chamber (12, 14) of the delayed flow comprises a resonator tube (11), provided that the ratio of the length of each resonator tube (11) of the resonators (10(R1), 10(R2)) to the length of corresponding inner expansion chamber (12, 14) of the delayed flow lies in the interval of 0.3 to 0.8, and the ratio of the cross-section surface of each resonator tube (11) to the cross-section surface of the inner exhaust gas supply pipe (2) lies in the interval of 0.3 to 0.8, and the surface size of the inlet openings (7) of the inner chambers (12, 14, 8) in the transverse partitions (7, 13) is the same ?10% as the surface size of the cross-section of the resonator tube (11), and wherein the sum of the lengths of all sequentially arranged inner expansion chambers of the non-delayed exhaust gas flow is the same ?10% as the sum of all lengths of all sequentially arranged inner expansion chambers of delayed flows.

2. Combined exhaust gas noise silencer according to the claim 1, wherein the inner expansion chambers (8) of the non-delayed flow and the inner expansion chambers (12, 14) of the delayed flow are separated by means of at least one elongated partition (9), longitudinal to the silencer axis.

3. Combined exhaust gas noise silencer according to the claim 1, wherein the number of sequentially arranged inner expansion chambers (12, 14) of the delayed flow is two.

4. Combined exhaust gas noise silencer according to claim 1, wherein each of the inner expansion chamber (12, 14) of the delayed flow is provided with the same resonator tube (11), provided that the ratio of the length of each tube (11) of the resonator ((10(R1), 10(R2)) to the length of the corresponding inner expansion chamber (12, 14) of the delayed flow is 0.5?0.1.

5. Combined exhaust gas noise silencer according to claim 1, wherein the ratio of the cross-section surface of each tube (11) of the resonator ((10(R1), 10(R2)) to the cross-section of the inlet exhaust gas supply pipe (2) is 0.5?0.1.

6. Combined exhaust gas noise silencer according to claim 1, wherein the size of the surface of the inlet openings (7) of the inner chambers in the transverse partitions (6, 13) is the same ?1% as the size the cross-section surface of the resonator tube (11).

7. Combined exhaust gas noise silencer according to claim 1, wherein the sum of all lengths of the sequentially arranged inner expansion chambers (8) of the non-delayed exhaust gas flow is the same ?1% as the sum of the lengths of all sequentially arranged inner expansion chambers (12, 14) of the delayed flows.

8. Combined exhaust gas noise silencer according to claim 1, wherein the inner cross-section of the resonator tube (11) of the resonator ((10(R1), 10(R2)) has the shape of one of the following: circular, oval, rectangular, trapezoidal, square, diamond, rhomboidal, polygonal, cascade.

9. Combined exhaust gas noise silencer according to claim 1, wherein the outlet end of the resonator tube (11) of the resonator ((10(R1), 10(R2)) has a rounded, convex or concave, shape.

10. Combined exhaust gas noise silencer according to claim 1, wherein the outlet (18) of the rear face of the silencer is a perforated partition or an ordinary piping.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0035] The invention will be further described using figures, in which the FIG. 1 illustrates a combined noise silencer, and the FIG. 2 illustrates a combined noise silencer with the indicated exhaust gas flows (?.sub.n ?.sub.z, ?.sub.p, ?.sub.v)

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0036] A combined exhaust gas noise silencer according to the FIGS. 1 and 2 consists of a system of hollow elements with a mutual housing 1 connected with an exhaust gas supply pipe 2 on one side and with an outlet part of the exhaust apparatus on the other side. The original inlet exhaust gas flow (?.sub.p) carrying a noise wave is divided into at least two flowsa delayed exhaust gas flow (?.sub.z) carrying a shifted noise wave with delayed wave length and non-delayed exhaust gas flow (?.sub.n) carrying a non-shifted noise wave with a non-delayed wave length. The exhaust gas flows are subsequently combined into a common exhaust gas flow (?.sub.s) carrying a noise wave with a phase shift, from which a resulting exhaust gas flow (?.sub.v) is formed after discharging the noise wave on the outlet. The system of hollow elements with the common housing 1 comprises on its inlet an inlet expansion chamber 5 and on the outlet an outlet expansion and mixing chamber 16. Between the inlet expansion chamber 5 and the common outlet expansion and mixing chamber 16, inner expansion chambers are arranged. The exemplary embodiment features one inner expansion chamber 8 of the non-delayed exhaust gas flow (?.sub.n) and preferably two inner expansion chambers: the first inner expansion chamber 12 of the delayed exhaust gas flow (?.sub.z) with the first resonator 10(R1) and the second inner expansion chamber 14 of the delayed exhaust gas flow (?.sub.z) with the second resonator 10(R2). Ratio of the length of each resonator tube 11 to the length of a corresponding inner expansion chamber 12, 14 of the delayed exhaust gas flow (?.sub.z) is preferably, and in this exemplary embodiment, 0.5. Ratio of the cross-section surface of the tube 11 of the first resonator 10(R1) to the cross-section surface of the inlet exhaust gas supply pipe 2 is preferably, and in this exemplary embodiment, 0.5. Ratio of the cross-section surface of the tube 11 of the second resonator 10(R2) to the cross-section surface of the inlet exhaust gas supply pipe 2 is preferably, and in this exemplary embodiment, 0.5. Ratio of the surface of the inner chamber inlet openings 7 in the partitions on the inlet and on the outlet of the inner expansion chamber 8 of the non-delayed flow (and on the outlet of the second inner expansion chamber 14 of the delayed flow to the cross-section surface of the inlet exhaust gas supply pipe 2) is preferably, and in this exemplary embodiment, 0.5. During passage of the delayed exhaust gas flow (?.sub.z) through the inner expansion chambers 12, 14 with the mentioned parameters, the wave length of the noise wave is in this case delayed by a whole ? and the noise wave is shifted by ? of its wave length ?, by means of which a mirror wave is formed in the combined exhaust gas flow (?.sub.s), and discharging of the noise waves or eventually of the whole noise spectrum occurs. In this exemplary embodiment, one inner expansion chamber 8 of the non-delayed exhaust gas flow (?.sub.n) is separated from the inner expansion chambers 12, 14 of the delayed exhaust gas flow (?.sub.z) by means of at least one elongated partition 9, longitudinal with the silencer axis, separating the non-delayed and the delayed exhaust gas flow after passing the inner expansion chamber 5, before entering the common outlet expansion and mixing chamber 16. The first inner expansion chamber 12 of the delayed exhaust gas flow (?.sub.z) with the first resonator 10(R1) continues with the second expansion chamber 14 of the delayed exhaust gas flow (?.sub.z) with the second resonator 10(R2). The inner expansion chambers 12, 14 of the delayed exhaust gas flow (?.sub.z) are arranged sequentially one after another without any other inserted elements, provided that the ratio of the length of each resonator tube 11 to the length of the corresponding inner expansion chamber 12, 14 of the delayed exhaust gas flow (?.sub.z) is preferably, and in this exemplary embodiment, 0.5, and the ratio of the cross-section surface of each resonator tube 11 to the cross-section surface of the inlet exhaust gas supply pipe 2 is preferably, and in this exemplary embodiment 0.5. The inner cross-section of the resonator tube 11 has preferably shape of a circle, rectangle, trapezoid, triangle, square, rhombus, parallelogram polygon or a cascade shape. In the preferred embodiment, the end of the resonator tube 11 has a rounded shape, convex or concave.

[0037] A combined noise silencer according to the present invention, according to the exemplary embodiment, consists of a common housing 1 of the system of hollow elements consisting of resonator and interference chambers, into which the inlet exhaust gas supply pipe 2 exits at the rear face 3 of the silencer via the opening 4 in the rear face of the silencer.

[0038] All parts of the silencer are rigid and immobile. All transverse, construction partitions 6, 13, 15 in the silencer system are, thanks to the inlet openings 7 of the inner chambers or the inlet openings 19 common with the outlet expansion and mixing chamber, permeable for the exhaust gas flows carrying a noise wave.

[0039] Tandem (sequential) tube resonators, i.e. the first resonator 10(R1) and the second resonator 10(R2), are connected together without any other inserted elementsmembers.

[0040] The first sub-system consists of the inlet expansion chamber 5, which is in this exemplary embodiment separated by means of a transverse 6 partition from the flow sub-system of the second branch carrying a shifted noise wave, consisting of the first inner expansion chamber 12 of the delayed flow with the first resonator 10(R1) and the second inner expansion chamber 14 of the delayed flow with the second resonator 10(R2), and at the same time it is separated by means of the transverse partition 6 from the flow sub-system of the left chamber carrying a non-shifted noise wave consisting of the inner expansion chamber 8 of the non-delayed flow.

[0041] The inner expansion chamber 5 is separated from the first inner expansion chamber 12 of the delayed flow with the first resonator by means of the transverse partition 6 with the opening 7 of the inner chamber, for the inlet into the tube 11 of the first resonator 10(R1), and from the inner expansion chamber 8 of the non-delayed flow by means of the transverse partition 6 with the inner opening 7 of the expansion chamber. The first inner expansion chamber 12 of the delayed flow with the first resonator is connected, by means of the transverse partition 13 with the inlet opening 7 of the inner chamber for an inlet into the tube 11 of the second resonator, with the second inner expansion chamber 14 of the delayed flow with the second resonator, wherein a common outlet expansion and mixing chamber 16 is connected therein by means of a transverse partition 15 with the inlet opening 19 of the common outlet and mixing chamber.

[0042] In this exemplary embodiment, in the left branch of the flow, a common outlet expansion and mixing chamber 16 is connected to the inner expansion chamber 8 of the non-delayed flow via a transverse partition 15 with the inlet opening 19 of the common outlet expansion and mixing chamber.

[0043] The first inner expansion chamber 12 of the delayed flow with the first resonator and the second inner expansion chamber 14 of the delayed flow with the second resonator are separated from the inner expansion chamber 8 of the non-delayed flow by means of an elongated partition 9.

[0044] A common outlet expansion and mixing chamber 16 in this exemplary embodiment is terminated with a perforated rear face 17 of the silencer with the openings on the outlet 18 from the rear face of the silencer into atmosphere. In another exemplary embodiment, an ordinary outlet piping exiting into atmosphere is arranged on the outlet instead of the perforated openings.

[0045] In a not illustrated case, the inner expansion chamber 8 of the non-delayed flow may be provided with another transverse partition 13 with the inlet opening 7 of the inner chamber.

[0046] In another exemplary embodiment, the whole system of inner chambers may be arranged so that the left and right sides are interchanged, or eventually the arrangement may be carried out using a tube in a tube method, i.e. using one chamber, for example the chamber with delayed flow may be surrounded by the second chamber with the non-delayed flow, and the other way around.

[0047] In another exemplary embodiment, the exhaust gas supply pipe 2 may be oriented towards the inlet expansion chamber 5 on the side of this chamber, as well as the openings 18 or the outlet pipe from the common outlet expansion and mixing chamber 16 on the side of this chamber.

[0048] The combined exhaust gas noise silencer is arranged in the axis of the exhaust gas supply pipe 2 on the side of the engine. Exhaust gases are supplied by means of the exhaust gas supply pipe 2 into the said noise silencer through the front face 3 of the silencer and through the opening 4 in the front face of the silencer. Exhaust gases are also the carrying medium of the noise wave, and thus the noise wave is affected in the similar manner as well. Exhaust gas flow enters the inlet expansion chamber 5 through the opening 4 in the front face of the silencer, where it is in this particular case divided into two branches, the right and the left branch. It enters the left branch through the inlet inner chamber opening 7 in the transverse partition 6, which at the same time separates the inlet expansion chamber 5 from the first inner expansion chamber 12 of the delayed flow with the first resonator.

[0049] The exhaust gas flow carrying a noise wave enters the right branch through the inlet inner chamber opening 7 for the tube 11 of the first resonator 10(R1) formed in the transverse partition 6. While the noise wave remains non-shifted in the left branch of the inner expansion chamber 8 of the non-delayed flow, the main noise wave in the right branch of the first inner expansion chamber 12 of the delayed flor with the first resonator, upon passage through the tube 11 of the first resonator 10(R1), settles in the axis of the resonator tube 11 as a quasi-half-wave, and its related waves are settled around, and the wave length in this case is delayed by ?/2 and thus the noise wave is shifted by ? of its wave length. After exiting the first inner expansion chamber 12 of delayed flow with the first resonator, the exhaust gas flows carrying a noise wave are moved to the second inner expansion chamber 14 of the delayed flow with the second resonator through the opening in the transverse partition 13 with the inlet opening 7 for the tube 11 of the second resonator. While the noise wave remains non-delayed in the left branch after passing the inner expansion chamber 8 of the non-delayed flow, the main noise wave in the right branch of the second inner expansion chamber 14 of the delayed flow with the second resonator, after passing the tube 11 of the second resonator 10(R2), is settled in the axis of the resonator tube 11 as a quasi-half-wave, and its related waves are settled around, and the wave length in this case is delayed by ?/2 and thus the noise wave is shifted only by ? of its wave length ?. In this case, the tubes 11 of the resonators 10(R1) and 10(R2) create the overall delay effect of the wave length by a whole ? and the shift of the noise wave by ? of its wave length ?. This is a positive shifta real mirror wave is formed.

[0050] The left branch carrying a non-shifted noise wave as well as the right branch carrying a noise wave shifted by ? of its wave length flow through the inlet openings 19 of the common expansion and mixing chamber in the transverse partition 15 with the openings into the common outlet expansion and mixing chamber 16 at the same time. Upon the impact on the rear face 17 of the silencer, the noise wave is automatically changed into the opposite phase, which is the most important for the function of the noise wave. The noise waves in this chamber interfere and their discharging occurs.

[0051] In one exemplary embodiment, the common outlet expansion and mixing chamber 16 is terminated with the perforated rear face 17 of the silencer, with the openings on the outlet 18 of the rear face of the silencer into the atmosphere. The function of this common outlet expansion and mixing chamber 16 with the rear face 17 of the silencer differs from the other embodiments in that the noise wave shifted by ? of its wave length meets with the phase opposite to the original wave. In this exemplary embodiment, the perforated openings on the outlet 18 of the rear face of the silencer silence the high-frequency noise components.

[0052] Within the examination, the tests with the following results were performed: [0053] a) influence of the ratio of the resonator length l.sub.1 to the inner expansion chamber length l.sub.2 on the value of the exhaust gas noise silencing, in the embodiment according to the FIG. 1 (with S.sub.1/S.sub.2=0.5 and the initial exhaust gas noise level of 79.2 dB)

TABLE-US-00001 s.n. l.sub.1/l.sub.2 silencing/dB 1 0.1 0.3 2 0.2 0.8 3 0.3 1.7 4 0.4 2.9 5 0.5 4.9 6 0.6 4.1 7 0.7 3.8 8 0.8 2.6 9 0.9 1.1 [0054] b) influence of the ratio of the resonator cross-section S.sub.1 (surface) to the cross-section S.sub.2 (surface) of the exhaust gas supply pipe on the noise silencing value, in the embodiment of the noise silencer according to the FIG. 1 (with l.sub.1/l.sub.2=0.5 and the initial exhaust gas noise level of 79.2 dB)

TABLE-US-00002 s.n. S.sub.1/S.sub.2 silencing/dB 1 0.1 0.6 2 0.2 1.2 3 0.3 1.7 4 0.4 3.6 5 0.5 4.9 6 0.6 4.0 7 0.7 3.2 8 0.8 2.4 9 0.9 1.8 10 1.0 1.2 11 1.1 1.0 12 1.2 0.7 [0055] c) influence of the combination of ratios of the resonator length l.sub.1 to the length l.sub.2 of the inner expansion chamber and the ratio of the resonator cross-section (surface) S.sub.1 to the cross-section (surface) S.sub.2 of the exhaust gas supply pipe on the value of the noise silencing in the noise silencer embodiment according to the FIG. 1

TABLE-US-00003 s.n. l.sub.1/l.sub.2 S.sub.1/S.sub.2 silencing/dB 1 0.1 1.0 0.3 2 0.9 0.1 0.3 3 0.9 1.2 0.4 4 0.3 0.3 0.8 5 0.3 0.4 1.1 6 0.3 0.5 1.7 7 0.3 0.6 1.8 8 0.3 0.7 2.0 9 0.4 0.3 0.8 10 0.4 0.4 2.6 11 0.4 0.5 2.9 12 0.4 0.6 2.6 13 0.4 0.7 2.2 14 0.5 0.4 3.6 15 0.5 0.5 4.9 16 0.5 0.6 4.0 17 0.5 0.7 3.2 18 0.6 0.4 3.5 19 0.6 0.5 4.1 20 0.6 0.6 3.8 21 0.6 0.7 3.4 22 0.7 0.4 1.9 23 0.7 0.5 3.8 24 0.7 0.6 3.9 25 0.7 0.7 4.0 26 0.7 0.8 3.9 27 0.7 0.9 2.8 28 0.8 0.5 2.6 29 0.8 0.6 2.8 30 0.8 0.7 2.9 31 0.8 0.8 3.2 32 0.8 0.9 3.0 33 0.1 0.1 0.4 34 0.1 0.7 0.6 35 0.1 0.9 0.3

[0056] Note: Noise level measurements were performed using a motor mower HECHT IP64FA with a combined exhaust gas noise silencer according to the FIG. 1 in the distance of 3 m from the source of noise (measurement was performed according to known recommendations for measurement of combustion engine noise). The given values are the statistical mean of 20 measurements.

[0057] The measured values and measurement results prove the optimum ratio of the lengths of the resonator tubes 11 to the length of the inner expansion chamber as well as the optimum ratio of the cross-section (surface) of the resonator tube 11 to the surface of the exhaust gas supply pipe 2.

INDUSTRIAL APPLICABILITY

[0058] The invention relates to a combined silencer of the exhaust gas noise, namely intended for automotive industry, forestry, agricultural and gardening equipment, but also applicable in the other fields of road transport, shipping and railway transport, forestry, agricultural and gardening equipment, further also in aviation and armament industry, and the like.

[0059] A combined silencer of the exhaust gas noise of the present invention may be preferably used in combustion engines, especially motor vehicles, and gardening equipment with a requirement for a high level of noise silencing.

LIST OF REFERENCE SIGNS AND THEIR DESCRIPTION

[0060]

TABLE-US-00004 Reference sign FIG. 1, FIG. 2 1 Mutual housing 2 Exhaust gas supply pipe 3 Front face of the silencer 4 Opening in the front face of the silencer 5 Inlet expansion chamber 6 Inlet transverse partition 7 Inlet opening of the inner chamber 8 Inner expansion chamber of the non-delayed flow 9 Elongated partition 10(R1) First resonator 10(R2) Second resonator 11 Resonator tube 12 First inner expansion chamber of the delayed flow 13 Transverse partition with an opening for the second resonator pipe 14 Second inner expansion chamber of the delayed flow 15 Outlet transverse partition 16 Common outlet expansion and mixing chamber 17 Rear face of the silencer 18 Outlet of the rear face of the silencer 19 Inlet opening of the common outlet expansion and mixing chamber

LegendDescription and Clarification of the Exhaust Gas Flows

[0061]

TABLE-US-00005 Reference sign Description i.sub.p Original inlet exhaust gas flow carrying a noise wave i.sub.z Exhaust gas flow carrying a shifted noise wave i.sub.n Exhaust gas flow carrying a non-shifted noise wave i.sub.s Unified exhaust gas flow carrying a noise wave with a phase shift i.sub.v Resulting exhaust gas flow after discharging the noise wave