RU200755U1 - PASSIVE SILENCER FOR AIR-CONDITIONING AND VENTILATION FOR PASSENGER CARS OF RAILWAY TRANSPORT - Google Patents

Abstract

The useful model of a passive muffler refers to technical solutions for noise reduction of air conditioning and ventilation systems in passenger cars of railway transport. The technical result of the claimed utility model is to simplify the design of the muffler, and, as a result, to reduce labor costs while maintaining the efficiency of noise suppression. The specified technical result is achieved by creating a passive muffler for the air conditioning and ventilation system of passenger cars of railway transport, consisting of a body in which a channel for air passage with a width smaller than the width of the inlet section of the ventilation duct is made, while one of the walls of the air passage channel is formed arched a perforated partition that creates a cavity filled with sound-absorbing material, and the second is formed by attaching a sheet of sound-absorbing material to the inner wall of the muffler body. In this case, the sound-absorbing material of the first and second walls is covered with a protective fabric, and the arcuate perforated partition can be made in one piece or consisting of several parts connected to each other.

Description

The proposed useful model of a passive muffler refers to technical solutions for noise reduction of air conditioning and ventilation systems for railway passenger cars.

Modern passenger cars are equipped with air conditioning and ventilation systems with high air flow rates up to 4800 m ³ / hour. To ensure such a flow rate, powerful fans are used in the air conditioning and ventilation system, the acoustic noise of which can negatively affect the comfort of passengers. The noise spreads through the air duct of the air conditioning and ventilation system and enters the passenger compartment through the ventilation holes. Due to multiple reflections from the walls of the duct, acoustic energy accumulates in the duct, which leads to an increase in the noise level in the duct, and, consequently, in the passenger compartment. One of the ways to reduce the noise generated by the fan of the air conditioning and ventilation system is to use a muffler, the principle of which is to absorb a part of the acoustic energy by the sound-absorbing material and convert it into heat. At the same time, the design feature of the air conditioning and ventilation system of railway cars is that the noise muffler can be placed inside the air duct at its inlet and at the same time the possibility of placing additional external sound insulating materials is excluded and the sound insulation effect is achieved only by the design features of the noise muffler.

Various designs of silencers are known in the art.

A noise muffler is known, which contains a housing in a cavity of which sound-absorbing elements are placed, adjacent in pairs to each other at the inlet, forming a tapering shape of channels for the passage of air, and having convex fairings at the points of abutment to each other, as well as a mechanism for their rotation, consisting of levers and rods-rods rigidly fixed at the ends of the sound-absorbing elements by means of washers and cotter pins, designed to reduce aerodynamic noise in the air ducts of mechanical ventilation and air conditioning systems (patent RU 2338964 C1, published on November 20, 2008).

Known honeycomb silencer containing a housing with inlet and outlet openings, located in the housing a package of perforated elements, forming parallel channels in the form of honeycomb, and placed in the honeycomb staggered sound-absorbing material, characterized in that the honeycomb is formed of flat perforated plate elements with slots and flat perforated plate elements without slots connected to each other (RU 23923, publication date 07.20.2002).

A noise muffler is known, which contains a rectangular body, inside which an air channel is located, formed from a pair of identical oppositely located arcuate elements forming an outlet section, connected to an inlet section formed from a pair of flat oppositely located perforated surfaces, while cavities formed by arcuate elements in the connection with flat perforated surfaces and a muffler body are filled with sound-absorbing material such as inorganic mineral wool (US patent 3511336 A, publication date 05/12/1970). The disadvantage of the known muffler, taken as a prototype, is the complexity of the design, as well as increased labor costs for its manufacture, associated with the need to install two flat perforated surfaces with arcuate elements.

The technical problem solved by the claimed utility model is to simplify the design of the silencer for the air conditioning and ventilation system of passenger cars of railway transport, while maintaining the level of absorption of sound energy entering the air duct of the air conditioning and ventilation system from the fan, and, consequently, the efficiency of noise suppression.

The technical result of the claimed utility model is to simplify the design of the muffler, and, as a consequence, reduce labor costs for manufacturing, while maintaining the effectiveness of noise suppression.

The specified technical result is achieved by creating a passive muffler for the air conditioning and ventilation system of passenger cars of railway transport, consisting of a body in which a channel for air passage is made with a width smaller than the width of the inlet section of the ventilation duct, while one of the walls of the air passage channel is formed arched a perforated partition that creates a cavity filled with sound-absorbing material, and the second is formed by attaching a sheet of sound-absorbing material to the inner wall of the muffler body.

The declared utility model is presented on:

- fig. 1 - a sketch of a passive noise muffler for the air conditioning and ventilation system of railway passenger cars;

- fig. 2 - a fragment of a sound-absorbing material with a protective fabric, in section.

Positions in the drawings:

1 - muffler body;

2, 3 - wall of the muffler body;

4 - channel for air passage;

5 - arcuate perforated partition;

6 - sound-absorbing material;

7 - a sheet of sound-absorbing material;

8 - protective fabric.

The proposed design of the utility model consists of a muffler body 1, a channel 4 for air passage into the air duct of the car's ventilation and air conditioning system. One of the walls of the duct for the passage of air 4 is formed by attaching an arcuate perforated partition 5 to the wall 3 of the muffler housing, and the cavity between the arcuate perforated partition 5 and the wall 3 of the muffler housing 1 is filled with sound-absorbing material 6, which is covered with a protective fabric 8. The second wall of the duct for the passage air 4 is formed by attaching a sheet of sound-absorbing material 7 to the wall 2 of the housing of the muffler, the thickness of which is less than the thickness of the wall of the channel 4, consisting of an arcuate perforated partition 5 filled with sound-absorbing material 6. In this case, the sheet of sound-absorbing material 7 is also covered with a protective fabric 8.

The arcuate perforated partition 5 of the passive muffler is made of a material with a thickness of 0.25≤δ≤3 mm, with a perforation coefficient of 0.25≤k≤0.80, and, due to perforation, provides access of sound waves to the sound-absorbing material 6. Material for manufacturing arcuate perforated partitions 5, as well as the housing of the muffler 1, can be steel, aluminum alloys or heat-resistant polymers.

The arcuate perforated partition can be made either in one piece or in several parts connected to each other. When making an arcuate perforated partition from several parts, beforehand, before installing the partition, its component parts are interconnected by any known method (for example, a weld seam, or a mechanical connection method is used using bolts, screws or rivets). At the same time, if the arcuate perforated partition is integral, the assembly of the partition is excluded, which leads to an additional enhancement of the specified technical result, which consists in simplifying the design of the muffler, as a result, reducing labor costs for manufacturing, while maintaining the efficiency of noise suppression.

As a sound-absorbing material for a passive muffler with a density of 10≤ρ≤600 kg / m3, the following can be used: mineral wool, glass wool, silica fibers, basalt fibers.

The sound-absorbing material of the first and second walls is covered with a protective fabric. The protective fabric 8 can be used, for example, glass fabric.

The sound-absorbing materials and protective fabric used must have fire-resistant and non-hygroscopic properties, as well as comply with the sanitary and hygienic norms and rules adopted in railway transport.

Fastening the sheet of sound-absorbing material 7 to the muffler body is carried out using mechanical fasteners (for example, bolts, screws, rivets, etc.), in addition, in addition to the mechanical method of joining, you can use adhesive joints or adhesive tapes (double-sided tape) with high degree of adhesion.

The passive silencer works as follows.

The air flow generated by the fan of the ventilation and air conditioning system of the passenger car of railway transport enters the air passage channel 4 of the passive muffler. Due to the fact that the passage section of the channel for the passage of air 4 of the passive muffler 1 is made 1.2-1.6 times less than the passage section of the ventilation channel of the passenger car, there is a concentration of sound power and its effective absorption by the sound-absorbing material 6 located inside the cavity formed by the arcuate perforated partition 7 and wall 3, as well as a sheet of sound-absorbing material 7, fixed to the wall 2. At the same time, due to the smooth rounding of the arcuate perforated partition 7 at the inlet, and especially at the outlet of the passive muffler air passage 4, the aerodynamic resistance in the ventilation duct of the passenger car the car is reduced, which contributes to maintaining the required level of noise suppression.

A passive noise muffler is located at the inlet of the car's ventilation duct and creates an obstacle to sound propagation in the passenger carriage. Such an arrangement of a passive noise damper makes it possible to reduce as much as possible the noise directly at its source and to exclude the use of additional sound-absorbing materials along the entire length of the ventilation duct of a passenger car, and the noise absorption effect is achieved only by the design features of the noise damper.

The retention of the efficiency of noise damping of the claimed design of the passive muffler is confirmed by the research results obtained during the testing of the experimental sample, which are presented in Fig. 3, and show the difference in 1/3-octave noise spectra generated by the fan in the air conditioning and ventilation channel, 9 - without a passive silencer, 10 - with a passive silencer installed in it.

The effect of noise reduction in the frequency range of 500-5000 Hz was at least 10 dBA, while the specified frequency range corresponds to the frequency distribution of the actual noise generated by the fan of the ventilation and air conditioning system of a railway passenger car.

Thus, in comparison with the prototype, the declared design of the passive muffler allows to exclude from the technological process the assembly and installation of one of the channel walls, consisting of an arcuate perforated partition and a sound-absorbing material, due to the channel wall made of a sheet of sound-absorbing material, while the efficiency of noise damping does not decrease. Consequently, the declared passive muffler provides a simplified design, a reduction in labor intensity and costs for its manufacture, as well as a decrease in the cost of the declared muffler, while maintaining the efficiency of noise reduction.

Claims (4)

1. A passive muffler of the air conditioning and ventilation system of passenger cars of railway transport, consisting of a body in which a channel for air passage with a width smaller than the width of the inlet section of the ventilation duct is made, characterized in that one of the walls of the channel for air passage is formed by an arcuate perforated partition, creating a cavity filled with sound-absorbing material, and the second is formed by attaching a sheet of sound-absorbing material to the inner wall of the muffler housing. 2. A passive muffler according to claim 1, characterized in that the sound-absorbing material of the first and second walls is covered with a protective fabric. 3. A passive muffler according to claim 1, characterized in that the arcuate perforated partition is made of one piece. 4. A passive muffler according to claim 1, characterized in that the arcuate perforated partition is made of several parts connected to each other.

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