RU2231652C2 - Muffler - Google Patents

Abstract

FIELD: mechanical engineering; power plants with internal combustion engines.

SUBSTANCE: proposed muffler has housing with intake and exhaust branch pipes divided into slot channels by longitudinal partitions made of stepped strips. Said slot channels are formed by successively alternating narrowing and widening sections in which length f narrowing section between widening sections is 0.8-1.2 of geometric mean of lengths of preceding and following widening sections along slot channel with alternation of section of narrowing and widening of adjacent slot channels over length of housing. Widening sections are provided with two longitudinal perforated partitions with summary areas of perforation F_n, F_n+1 in partitions of nth and nth+1 widening sections in direction of slot channel related as lengths l_n, l_n+2 of said sections.

EFFECT: improved noise suppression.

3 dwg

Description

The invention relates to the field of engineering, in particular power engineering, and in particular to silencers, mainly power plants, such as internal combustion engines, and is an improvement of the known device described in the copyright certificate 1590611 [1].

Known silencer [1] contains a housing with inlet and outlet pipes, separated by longitudinal partitions into slotted channels. The channels are formed by successively alternating sections of narrowing and expansion. The length of the narrowing section between the expansion sections is 0.8-1.2 of the geometric mean lengths of the preceding and following the channel of the expansion sections. The longitudinal partitions are made of strips of stepped form. The areas of narrowing and expansion of adjacent slotted channels are placed alternating along the length of the housing.

In the known silencer, sound reflectors are slotted expansion chambers formed by narrowing and expanding portions. The sequential smooth change of the lengths of the expansion sections in the channels ensures the maximum efficiency of the cameras at closely spaced frequencies and determines the required even wideband noise reduction by the device. However, with a limited length of the muffler and a normalized range of noise attenuation of 63-8000 Hz, there is a need for a non-smooth change in the lengths of the expansion sections in the channels. The step of change can be up to two times, which ensures maximum efficiency of slotted chambers in the narrow range of each of 8 octaves. For frequencies 1/3 octave apart from the frequencies of maximum efficiency, the damping value is reduced to 4-5 dB. This determines the low noise attenuation efficiency of the known device, since in the case of the required equal broadband noise reduction, the noise attenuation efficiency depends on the amount of minimum attenuation.

The technical result of the invention is to increase the efficiency of sound attenuation.

The technical result is achieved in that in a noise suppressor comprising a housing with inlet and outlet nozzles, separated by longitudinal partitions made of step-shaped strips, into slotted channels formed by successively alternating narrowing and expansion sections, for which the length of the narrowing section between the expansion sections is 0 , 8-1.2 geometric mean lengths of the preceding and following expansion slots along the slotted channel, with alternating narrowing and widening sections of adjacent slotted channels along the length of the housing, the expansion sections are provided with two longitudinal perforated partitions, and

F _n / F _{n + 1} = l _n / l _{n + 1} ,

where F _n , F _{n + 1} - the total area of perforation in the partitions of the n-th and n + 1-th along the slot channel of the expansion areas, m ² ;

l _n , l _{n + 1} - the lengths of the n-th and n + 1-th along the slot channel of the expansion sections, m

We experimentally established that the use of perforated partitions with the indicated ratios of the perforation areas and the lengths of the expansion sections in the channels allows to increase the damping at the transmission frequencies of slotted expansion chambers, without compromising performance at the frequencies of their maximum damping. This provides a rise in the characteristics of the minimum silencing, graphically obtained by connecting the smallest values on the characteristic of the silencer, over the entire normalized frequency range and, as a result, increase the efficiency of sound attenuation.

Figure 1 shows a silencer, longitudinal section; figure 2 is a section aa in figure 1; figure 3 - characteristics of the minimum silencing.

The noise suppressor comprises a housing 1 with inlet 2 and exhaust 3 nozzles, separated by longitudinal partitions 4 into slotted channels 5. The slotted channels 5 are formed by successively alternating sections of narrowing 6 and expansion 7, and the expansion sections 7 are provided with two longitudinal perforated partitions 8. Total area perforations F _n , F _{n + 1} in the longitudinal perforated partitions 8 of the nth and n + 1th along the slot channel 5 of the expansion sections 7 are related in the same way as the lengths l _n , l _{n + 1 of} these expansion sections 7.

Silencer works as follows.

The gas stream with sound waves propagating in it through the inlet pipe 2 enters the cavity of the housing 1, where it is distributed through the slotted channels 5, passes through them and is discharged through the outlet pipe 3 into the environment or an adjacent gas duct element. Due to the difference between the volumes of the expansion sections 7 and the volumes formed between the perforated partitions 8 in the expansion sections 7, when the gas moves, part of the sound waves is resonantly reflected, which determines the partial attenuation of sound. Performing the perforation of the partitions 8 in the expansion areas 7 with the ratio F _n / F _{n + 1} = l _n / l _{n + 1} , where F _n and F _{n + 1} are the total perforation areas, m ² , al _n and l _{n + 1} - lengths, m of the n-th and n + 1 along the slot channel 5 of the expansion sections 7, provides broadband jamming.

The supply of the expansion sections 7 with two longitudinal perforated partitions 8 causes the appearance of the minimum silencing 9 of the proposed muffler in comparison with the characteristic of the minimal silencing 10 of the prototype, a resonant additive, which increases the noise suppression efficiency.

Sources of information

1. SU, copyright certificate 1590611, cl. F 02 M 35/12, F 01 N 1/00, 1990.

Claims (1)

A noise suppressor comprising a housing with inlet and outlet nozzles, separated by longitudinal partitions made of stripe-shaped strips, into slotted channels formed by successively alternating narrowing and expansion sections, for which the length of the narrowing section between the expansion sections is 0.8-1.2 geometric mean the lengths of the preceding and following it along the slit channel expansion sections, with alternating sections of narrowing and expansion of adjacent slotted channels along the length of the housing, characterized in that expansion kits are provided with two longitudinal perforated partitions, moreover F _n / F _{n + 1} = l _n / l _{n + 1} , where F _n , F _{n + 1} - the total area of perforation in the partitions of the n-th and n + 1-th along the slot channel of the expansion areas, m ² ; l _n , l _{n + 1} - the lengths of the n-th and n + 1-th along the slot channel of the expansion sections, m

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