GB2118245A

GB2118245A - Intake air silencer and cleaner for an IC engine

Info

Publication number: GB2118245A
Application number: GB08303754A
Authority: GB
Inventors: Mikhail Ilich Fesina; Rudolf Natanovich Starobinsky; Jury Petrovich Lazarev; Evgeny Vasilievich Lysenko; Petr Andreevich Pimakhin
Original assignee: VOLZH OB PROIZV; VOLZHSKOE OBIEDINENIE PO PROIZVODSTVU LEGKOVYKH AVTOMOBILEI
Current assignee: VOLZH OB PROIZV; VOLZHSKOE OBIEDINENIE PO PROIZVODSTVU LEGKOVYKH AVTOMOBILEI
Priority date: 1982-04-12
Filing date: 1983-02-10
Publication date: 1983-10-26
Also published as: SE8301985L; IT1193688B; IT8319787A0; SE8301985D0; FR2524815A1; DE3304858A1; GB2118245B; GB8303754D0; FR2524815B1

Abstract

A casing 1 in the form of a circular cylinder has an inlet port 5, a cover 2 and a bottom 3 having an outlet port 6. In the cover 2 and/or in the bottom 3 are holes 7, 7' arranged in the zone confined by two planes located at a distance of +/-0.1 R, where R is the radius of the casing 1, from the plane passing through an axis 9 to the casing 1 perpendicularly to the plane containing the casing axis 9 and the outlet port centre 10. The holes 7, 7' may be between 0.58 and 0.68R from the axis 9 and contain porous filter elements (8 Fig. 3). The presence of the holes 7, 7' reduces the noise emitted from the air cleaner. <IMAGE>

Description

SPECIFICATION Air cleaner for internal combustion engine The invention relates to the engine manufacturing industry and, more particularly, to air cleaners for internal combustion engines.

The invention may preferably be used in air cleaners for feed systems of all the trasport internal combustion engines: automobile, marine, locomotive, etc. and also stationary engines, for example, for driving generators, compressors, etc., especially in those cases when it is necessary to reduce the noise radiated into the environment.

The invention essentially resides in that in an air cleaner for an internal combustion engine, comprising a casing with holes, made in the form of a circular cylinder confined at the top with a cover and on the underside, with a bottom and accommodating internally a filter element disposed coaxially therewith, inlet and outlet ports being made in the casing and the bottom respectively, according to the invention the holes are made at least in the cover or in the bottom of the casing and are arranged in the zone confined by two planes located at a distance of + 0.1 R, where R is the radius of the casing, from the plane passing through the axis of the casing perpendicularly to the plane combining the axis of the casing and the centre of the outlet port.

The holes may advantageously be made both in the cover and in the bottom.

Such a design of the air cleaner makes it possible to effectively reduce the level of sound radiation caused by the forms of pressure fluctuations in the air cleaner chamber.

It is also desirable to arrange the holes at a distance of (0.58-0.68)R from the geometrical centre of the air cleaner casing, where R is the radius of the air cleaner casing, which corresponds to arrangement of the holes near the nodal line of a lower radial form of pressure fluctuations.

This allows the level of sound radiation caused by radial forms of the pressure fluctuations in the air cleaner chamber to be effectively reduced.

Thus, a reduction in the level of radiation caused by natural forms of the pressure fluctuations in the air cleaner chamber is achieved by way of arranging the holes in the nodes (on zero lines) of tangential and radial forms of fluctuations of the air volume in the air cleaner chamber.

Besides, the provision of the holes in the vibrating cover of the air cleaner reduces the radiation produced by the cover due to equalization of the pressure pulses arising at the opposite sides of the vibrating cover.

The holes in the cover and the bottom of the air cleaner may suitably be provided with porous elements.

This makes it possible to impart an active character to the conductance of holes and to increase the efficiency of suppressing the lowfrequency components of the intake noise.

In addition to reduction of the noise, the provision of holes in the cover and in the bottom of the air cleaner decreases the flow resistance of the intake system which allows the power and economic characteristics of an engine to be improved.

Due to the fact that the effects heretofore described are achieved by exclusively simple means, the design of the air cleaner is simplified and its compactness improved.

The invention will now be described in greater detail with reference to specific embodiments thereof, taken in conjunction with the accompanying drawings, in which: Figure 1 illustrates an air cleaner for an internal combustion engine; Figure 2 is a section taken on the line ll-ll of Fig. 1; Figure 3 is a section taken on the line Ill-Ill of Fig. 1 (drawn to an enlarged scale); Figure 4 illustrates a sound pressure profile in the air cleaner chamber, a tangential component; Figure 5 illustrates a sound pressure profile in the air cleaner chamber, a radial component; Figures 6 through 10 present comparative spectrograms of noise, clearly illustrating the achieved effect; Figure ii illustrates an external speed characteristic of the engine;; Figure 12 illustrates a spectrogram of noise radiated by the air cleaner cover.

An air cleaner for an internal combustion engine (Figs. 1, 2) comprises a casing 1 made in the form of a circular cylinder confined at the top with a cover 2 and on the underside, with a bottom 3 (Fig. 1) and accommodating internally a filter element 4 disposed coaxially therewith. An inlet port 5 is made in the casing 1 and an outlet port 6 (Fig. 2) is made in the bottom 3 (Fig. 1). Holes 7 and 7' are made respectively in the bottom 3 and in the cover 2 of the casing 1, and the holes 7 and 7' especially those arranged in the internal space of the filter element 4 may suitably be provided with porous elements 8 (Fig. 3) for protecting the engine intake system against ingress of dust and also for improving the acoustical characteristics of the air cleaner.

The holes 7 and 7' in the bottom 3 and in the cover 2 of the casing 1 are arranged in a zone A (Fig. 4) confined by two planes disposed at a distance of + 0.1 R (R is the radius of the casing 1) from the plane passing through an axis 9 (Fig. 1) of the casing 1 perpendicularly to the plane combining the axis 9 of the casing 1 and a centre 10 (Fig. 4) of the outlet port 6. The holes 7 and 7' may be made both in the cover 2 and in the bottom 3, and separately only in the cover 2 or only in the bottom 3 of the casing 1 depending on the design features of air cleaners. The holes 7 and 7' (Fig. 5) may suitably be arranged at a distance of (0.58-0.68)R from a geometric centre 11 of the casing 1, where R is the radius of the air cleaner casing 1.

The air cleaner operates in the following way.

At the basic frequency of the working process the air volume in an air intake branch pipe 1 2 (Fig. 4) fluctuates as a mass, while the air volume of the air cleaner casing 1 (Figs. 1 and 2) acts as a resilient spring. In this case, in addition to the fact that the air is drawn in through the air intake branch pipe 12 (Fig. 4), the air is also drawn in through the holes 7 and 7' in the bottom 3 and in the cover 2 (Fig. 1). This reduces the flow resistance of the air cleaner on the whole and increases the effective power of an engine. On the other hand, the provision of the holes 7 and 7' may be considered as the parallel connection of an oscillation damper to the air volume in the casing 1 as these holes cause additional losses of energy at suction of the air charge.At the same time the radiation of sound energy from the casing 1 into the environment is substantially reduced as the holes 7 and 7' are disposed on the nodal line of the tangential fluctuations of the air volume in the casing 1 (Fig. 4), that is in the zone A where the resonant pulsating component of the air volume fluctuations approaches or is equal to zero. The width of the zone A amounts to 0.2 R, i.e. 0.1 R on either side of the plane perpendicular to the plane combining the axis 9 (Fig. 1) and the centre of the outlet port 6 (Fig. 2). At greater distances from said plane the pressures in the tangential form B are no longer low and the transmission of sound through the holes 7 and 7' becomes perceptible (Fig. 4).

The holes 7 and 7' sharply reduce the Qfactor of the resonant system at the intake stroke of the engine and the resonant lowfrequency sound radiation due to the introduction of incremental active losses and do not produce an added radiation from the tangential form of the pressure fluctuations in the casing 1.

In addition, the provision of the holes 7' in the cover 2 reduces the radiation produced by the vibrating cover 2 owing to equalization of the pressure pulses occurring at the opposite sides of the cover 2.

It is also expedient to locate the holes 7 and 7' (Fig. 4) in the cover 2 (Fig. 1) and in the bottom 3 in a zone D (Fig. 5) at a distance of (0.58-0.68)R from the centre 11, i.e. in the zone of low sound pressures of the first radial form C of the pressure fluctuations in the casing 1. As a result, the transmission of the energy of fluctuations of the first radial form through the holes 7 and 7' is prevented.

Making the holes 7 (7') closer than 0.58R to the centre 11 and farther than O.fi8R from the centre does not produce the above-mentioned effect, as the pressures in the form of C fluctuations beyond the zone D are no longer sufficiently low.

An additional positive effect is achieved if the holes 7 and 7' (Fig. 1) are provided with the porous elements 8 (Fig. 3). The porous elements 8 may be made, for example, from the alloy of copper fluoride and cathode copper or from a porous polyethylene. As has been proved by the theoretical analysis and experiments, the best are the porous elements 8 possessing a specific conductance.

F, Vg=(0.5-2.0) (1) pa,1 where p is the density of gas (kg/m3); w is the angular frequency of the first harmonic at a maximum power speed (sec-'); I is the length (m) of the branch pipe 1 2 (Fig.

4); F, is the cross-section area (m2) of the branch pipe 12; Vg is the specific portion of the total conduct ance of the porous elements 8.

This makes it possible to impart an active character to the conductance of the holes with an optimal value determined by the formula (1) and to substantially increase the efficiency of suppressing the low-frequency components of the intake noise.

A similar effect for high speed engines is achieved by making the holes 7 (7') not provided with the porous elements 8 and having the total area (F2) determined by the formula F2 = F1(0.01 -0.08) - (2) wl c where c is the sound velocity (m/s).

Figs. 6 through 10 present the comparative spectrograms of noise, illustrating the achieved positive effect at different engine speeds. The solid curve a in these Figures illustrates the spectra of the noise produced by the intake system not provided with the holes 7 and 7', the dashed curve b illustrates the same for the intake system provided with the holes. A substantial reduction (up to 10 dB) of the noise ensured by the claimed air cleaner is seen from these spectrograms.

Fig. 11 presents the external speed characteristics of the engine having an air cleaner with and without holes, shown respectively by the dashed line dand the solid line c. Increase in the power at a high speed amounts to 3 hp.

Fig. 1 2 presents the spectrograms illustrat ing the reduction of noise radiated by the vibrating cover 2 (Fig. 1) of the air cleaner in which the cover is provided with the holes 7', shown by the dashed curve e. The solid curve x shows the spectrum radiated by the cover 2 without the holes 7'. Positive effects at separate frequencies amount to 4-7 dB.

Thus, the air cleaner for an internal combustion engine provides a substantial reduction of the intake noise.

Claims

1. An air cleaner for an internal combustion engine, comprising a casing with holes, made in the form of a circular cylinder; the casing is confined at the top with a cover and has an inlet port, and on the underside, with a bottom having an outlet port; said holes of the casing are made at least in the cover or in the bottom of the casing and are arranged in the zone confined by two planes located at a distance of + 0.1 R, where R is the radius of the casing, from the plane passing through the axis of the casing perpendicularly to the plane combining the axis of the casing and the centre of the outlet port; said casing accommodates internally a filter element disposed coaxially therewith.

2. An air cleaner for an internal combustion engine according to Claim 1, in which the holes are made both in the cover and in the bottom.

3. An air cleaner for an internal combustion engine according to Claims 1 and 2, in which the holes are arranged at a distance of (0.58-0.68)R from the geometrical centre of the air cleaner casing, where R is the radius of the casing.

4. An air cleaner for an internal combustion engine according to Claims 1 through 3, in which the holes are provided with porous elements.

5. An air cleaner for an internal combustion engine substantially as herein described with reference to and as illustrated in the accompanying drawings.