FR2524815A1 - AIR FILTER FOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

THE INVENTION RELATES TO THE CONSTRUCTION OF ENGINES. THE AIR FILTER WHICH IS THE OBJECT OF THE INVENTION IS OF THE TYPE INCLUDING A BODY 1 PROVIDED WITH ORIFICES 7, 7, MADE IN THE FORM OF AN ANNULAR CYLINDER BOUNDED AT ITS UPPER PART BY A CAP, AND IN ITS LOWER PART, BY A BOTTOM, AND WITHIN WHICH, COAXIALLY AUDIT BODY, IS AVAILABLE A FILTERING ELEMENT, AN INLET OPENING AND AN EXHAUST OPENING 6 BEING PRACTICED IN THIS BODY AND IN SUCH BODY, RESPECTIVELY, AND IS CHARACTERIZED IN THIS THAT HOLES 7 AND 7 ARE PRACTICAL AT LEAST IN THE CAP OR IN THE BOTTOM OF THE BODY 1 AND ARE ARRANGED IN ZONE A DELIMITED BY TWO PLANS ARRANGED AT A DISTANCE OF 0.1R, WHERE R IS THE RADIUS OF BODY 1, BY RELATION TO THE PLANE PASSING THROUGH THE BODY AXIS 1 PERPENDICULARLY TO THE PLANE CONNECTING THE BODY AXIS 1 AND THE CENTER 10 OF THE EXHAUST OPENING 6. THE INVENTION APPLIES IN PARTICULAR TO THE AIR FILTERS OF INTERNAL COMBUSTION ENGINES OF THE MEANS OF TRANSPORT SUCH AS: MOTOR VEHICLES, SHIPS, LOCOMOTIVES , ETC.

Description

The invention relates to the field of engine construction and to

especially for a

  internal combustion engine air filter.

  The invention can be applied, preferably, to the air filters of the supply systems of all the internal combustion engines of the means of transport such as: motor vehicles, ships, locomotives, etc., as well as fixed installations, for example example, generators, compressors, etc., especially in cases where there is a need to reduce the noise emitted in the surrounding environment. During engine operation, the main frequency of the working process is found

  in a range from 100 Hz (for single-phase motors

  sectional with rotary pistons (i.e. for four-stroke internal combustion two-cylinder engines) up to

  Hz for in-line, gasoline four-cylinder engines.

  To lower the sound pressure level in the mentioned frequency ranges, significant difficulties must be overcome. To lower it, for example, by means of an acoustic adjustment which is carried out by lengthening the air intake pipe for these low frequencies, we are obliged to significantly increase its length and to increase the quality of the metal necessary for its manufacture, to weigh down the construction and to complicate the organization of the engine compartment of the motor vehicle. important, specific to this measure, which is that the power of the engine and its engine torque are reduced The decrease in low frequency radiation at the air intake by a large increase in the volume of the filter chamber air or by connecting parallel volumes of air is

  Characterized by the drawbacks already described above.

  An air filter design is known (see, for example, the USSR author's certificate NI 293 135, cl F 02 M 35/14 published on January 15, 1971), which comprises a body with two walls in which are provided semi-annular air channels These channels are of identical length and their inlet ports are arranged on the

  diametrically opposite sides of the body This embodiment

  tion increases the noise reduction efficiency

  and somewhat reduce the hydraulic resistances.

  However, this design is quite complicated and requires a significant amount of metal for its manufacture. Another source of intense emission of the sound emitted by the air filter is its cap in the case where it is made of thin, slightly rigid sheet metal,

  thus being the element most susceptible to bending.

  In order to reduce the emission of sound resulting from structural vibrations due to the bending of the caps of the air filters, use is made either of higher quality insulation against vibrations of the cap along the perimeter of its attachment to the body and at the places where it is tightened by fastening elements, or to methods of raising the impedance of the cap by applying to its surface a developed skeleton of fins All this

  leads to a complication of the design, to an increase

  tion of the amount of metal consumed, a complication

of the whole organization.

  We know of an air filter design which makes little noise (see, for example, French patent NO 2 307 975, cl F 02 M 35/14, published on December 17, 1976) intended for internal combustion engines. known air comprises a cover intended for protection against vibrations and inside which is housed a filter element The cover assembled with the filter element is usually mounted in the body of the air filter The protective cover is executed either in the form of '' a separate part or in one piece with the filter body

air.

  The disadvantage of this filter is that it is complicated in the first place, that it is necessary to increase the quantity of parts, of their fixings and to determine an optimal organization for a concrete design of the filter. In addition, this contributes an increase in the quantity of metal consumed and the manpower for its manufacture. An air filter design is known (see, for example, the Japanese review "Dzidosia guidziutsu", 1966, volume 20, NO 9, pages 861 to 865), in which, in order to reduce the hydraulic resistances, to raise the economic performances and those of the engine power, we made holes in the chamber By depositing the calibrated holes in any place of the chamber we managed to reach the goal, because during the "compression-expansion" of the volume of air, in the chamber an additional portion of air is sucked through these orifices, which does not enter the air intake pipe However, as it is said in said Japanese review: "consequently, the sound propagates without entering the suction pipe ", which increases

  radiation from noise emitted by the intake system.

  It has therefore been proposed to develop a simpler and more compact design of the air filter for an internal combustion engine, which would ensure a reduction in the sound pressure level of the low and medium frequency components of the system noise. intake, as well as an increase in economic performance and engine power thanks to the

  modification of the design of the air filter body.

  The problem thus posed is resolved using an air filter for an internal combustion engine, comprising a body with orifices produced in the form of a circular cylinder delimited at the top by a cap and at the bottom by a bottom, at the interior of which is housed a filter element coaxial with said body, an inlet opening and an exhaust opening being formed in the body and in the bottom, respectively, characterized, according to the invention, in that the orifices are made at least in the cap or in the bottom of the body and are arranged in the area delimited by two planes which are at a distance equal to the value + 0.1 R, where R is the radius of the body from the plane passing through the axis of the body perpendicular to the plane connecting the axis of the

  body and center of the exhaust opening.

  It is advantageous to practice the orifices

  simultaneously in the hat and in the bottom.

  This design of the air filter makes it possible to effectively lower the level of the radiation of sound due to the forms of pressure oscillations in the chamber.

of the air filter.

  It is also advantageous to have the

  orifices at a distance of 0.58 to 0.63 R from the geometrical center

  size of the air filter body, where R is the radius of the air filter body, which corresponds to the case of the arrangement of the orifices in the vicinity of the line of the nodes of the

  lower radial shape of vibrations.

  This effectively lowers the level of sound radiation from the radial shapes of

  pressure oscillations in the air filter chamber.

  Thus, the drop in the level of radiation due to the shapes of the pressure oscillations in the air filter chamber is obtained by means of the orifices arranged

  in the nodes (reference line) tangent forms

  radial and air volume of the chamber

air filter.

  In addition, the holes in the vibrating cap of the air filter reduce the radiation of sound produced by the cap thanks to the equalization of the pressure pulses generated on the opposite sides of the cap.

during its vibrations.

  Cap holes can be closed

  and those at the bottom of the air filter by porous elements.

  This gives the conductivity of the orifices an active character and increases the efficiency of the suppression

  low frequency components of intake noise.

  In addition to noise reduction, the holes in the bonnet and in the bottom of the air filter reduce the hydraulic resistance of the intake system, which improves economic performance and

those of engine power.

  Thanks to the fact that all of the above mentioned effects are obtained exclusively by simple means,

  the device obtained is simpler and more collected.

  The invention will be better understood and other objects, details and advantages thereof will appear better on

  light of the explanatory description which follows

  various embodiments given only by way of nonlimiting examples with reference to the appended drawings in which: FIG. 1 represents an air filter for an internal combustion engine: FIG. 2 is a section along line II-II of the figure 1; Figure 3 is a section along line III-III of Figure 1 (on an enlarged scale); FIG. 4 shows a diagram of the distribution of the acoustic pressures in the air filter chamber (tangential component); FIG. 5 shows a sketch of the distribution of the acoustic pressures in the air filter chamber (radial component);

  Figures 6 to 10 show the spectro-

  comparative noise grams clearly illustrating the effect obtained;

  figure 11 shows the external characteristic

  engine speed; FIG. 12 represents a spectrogram of the

  noise emitted by the air filter cap.

  The air filter for internal combustion engine (Figures 1, 2), according to the invention, comprises a body 1 executed in the form of an annular cylinder delimited at the top by a cap 2 and at the bottom by a bottom 3 (Figure 1) and inside which, coaxially with said cap, is housed a filter element 4 An intake opening 5

  is practiced in the body 1 and an escape opening

  ment 6 (figure 1) is made in the bottom 4 (figure 2).

  Ports 7 and 7 'are made in the bottom 3 and in the cap 2 of the body 1, respectively. It should be noted that to protect the engine intake system

  against dust, as well as to improve the characteristics

  acoustic characteristics of the air filter, it is desirable to close the orifices 7 and 7 ', especially the orifices arranged in the enclosure of the filter element 4 The orifices 7 and 7' of the bottom 3 and of the cap 2 of the body 1 are arranged in zone A (figure 4) delimited by two planes arranged at a distance + 0.1 R (where R is the radius of body 1) from the plane passing through axis 9 (figure 1) of body 1 perpendicular to the plane connecting axis 9 of

  body and center 10 (Figure 4) of the exhaust opening

  ment 6 The orifices 7 and 7 'can be made either in the cap 2 and the bottom 3, or only in the cap 2, or only in the bottom 3 of the body 1, depending on the characteristics of the filter design It is desirable that the orifices 7 and 7 '(Figure 5) are located at a distance of 0.58 R to 0.68 R from the geometric center 11 of the body 1 (where R is the radius of the body 1

of the air filter).

  The claimed air filter operates from the

next way.

  While the engine is running at main speed, the volume of air in the air intake manifold 12 (Figure 4) vibrates as a mass, while the volume of air in body 1 (Figures 1 and 2) air filter acts as an elastic spring In this case, in addition to the air intake through the air intake pipe 12 (FIG. 4), the air is also sucked through the openings 7 and 7 ' of the bottom 3 and of the cap 2 (FIG. 1) This reduces the hydraulic resistances of the air filter assembly and increases the effective power of the engine. On the other hand, the introduction of the orifices 7 and 7 'amounts in a way to introduce a vibration damper connected in parallel with the volume of air in the body 1, because they create additional losses of energy at the suction of the air charge At the same time, the radiation of the acoustic energy of the body 1 in the surrounding medium decreases because the orifices 7 and 7 'are arranged on the line of vibration knots t of the air volume of the body 1 (FIG. 4), that is to say in the zone A where the pulsed resonant component of the vibrations of the air volume approaches zero or is equal to zero The width of the zone A is 0.2 R, 0.1 R on each side of the perpendicular plane

  to the plane connecting the axis (Figure 1) and the center of the opening

  exhaust ture 6 (Figure 2) At greater distances from said plane, the pressures in the tangential form B are not already low and the transmission of sound through the orifices 7 and 7 'becomes

sensitive (Figure 4).

  The orifices 7 and 7 ′ substantially reduce the quality factor of the resonance system at the time of admission of the engine and the low frequency resonant acoustic radiation, as a result of the introduction of additional active losses and produce no additional radiation of the form. tangential of the oscillations

pressure in the body 1.

  In addition, the orifices 7 'made in the

  cap 2 decrease the radiation produced by the cover

  key 2 during its vibrations, thanks to the equalization of the pressure pulses generated on the opposite sides

hat 2.

  It is also advantageous to arrange the orifices 7 and 7 ′ (FIG. 4) of the cover 2 (FIG. 1) and of the bottom 3 in the zone D (FIG. 5), at a distance of 0.58 R to 0.68 R from the center 11, in the zone of low acoustic pressures of the first radial form C of the variations of the pressure in the body 1 One thus prevents the transmission of the energy of the oscillations of the first radial form When the orifices 7, 7 'are practiced at a distance less than 0.58 R from the center 11 and greater than 0.68 R from the latter, the effect mentioned is not obtained, because outside of zone D the pressures in the form C oscillations are already

insufficiently weak.

  An additional positive effect is obtained if the orifices 7 and 7 ′ are closed off (por 1) by porous elements 8 (fig 3) The porous elements 8 can be made, for example, of a copper alloy

  phosphorous and cathodic or porous polyethylene.

  As appears from the theoretical analysis and from the tests carried out, the porous elements 8 of which the conductivity

  active conforms to the following relationship are the best

  their: FF Yg = (0.5 to 2.0) 1 (1) o: is the density of the gas, kg / m 3 Ad is the circular frequency of the first harmonic at the speed of rotation of the maximum power (81 ); is the length in meters of the tubing 12 (Figure 4); F is the surface in m 2 of the section of the tubing 12; Yg is the active part of the conductivity

total of porous elements 8.

  This makes it possible to give the conductivity of the orifices an active character with an optimal value determined by formula (1) and to substantially increase the effectiveness of the attenuation of the bass components.

intake noise frequencies.

  A similar effect is obtained for fast motors if the orifices 7 (7 ′) are produced without closing them with the porous elements 8 and with a total surface (F 2) determined using the following formula:

F 2 = F 1 (0.01 to 0.08) (2)

vs

where c is the speed of sound, m / s.

  Figures 6 to 10 represent comparative spectrograms illustrating the positive effect obtained at the different engine rotation speeds. The continuous curves (a) represent in these figures the spectra of the noise produced by an intake system without orifices 7 and 7. '(Figure 1), and the dashed lines (b),

  those of a system with orifices We see the dimi-

  sensitive noise reduction up to 10 d B, obtained using

of the claimed air filter.

  Figure 11 gives the external speed characteristic of the engine fitted with an air filter without orifices, shown in solid line (c), and that of a engine provided with an air filter with orifices, represented in dashed lines. (d) At high rotational speeds, an increase in power of 2.2 kW is obtained.

  Figure 12 shows the spectrograms illus-

  trating the reduction in the noise emitted by the vibrating cap 2 (FIG. 1) of the air filter in which the holes 7 ′ are made (dashed line curve e) The curve in solid line x represents the spectrum of the radiation of the cap 2 without holes 7 'The positive effect obtained at certain frequencies is from 4 to 7 d B. It follows that the air filter which is the subject of the invention ensures a considerable reduction in the

noise on admission.

Claims (4)

R E V E N D I C A T I O N S   1. Air filter for internal combustion engine, comprising a body (1) provided with orifices (7 and 7 '), produced in the form of an annular cylinder delimited at its upper part by a cap (2), and at its lower part, by a bottom (3) tet inside of which, coaxially with said body, is disposed a filter element (4), an intake opening (5) and an exhaust opening (6) being formed in said body (1) and in said bottom (3), respectively, characterized in that the orifices (7 and 7 ') are made at least in the cap (2) or in the bottom (3) of the body (1) and are arranged in the zone (A) delimited by two planes arranged at a distance of + 0.1 R, where R is the radius of the body (1), relative to the plane passing through the axis (9) of the body (1) perpendicular to the plane connecting said axis (9) of   body (1) and the center (10) of the exhaust opening (6).   2. Air filter for internal combustion engine, according to claim 1, characterized in that the orifices (7 and 7 ') are made both in the cap (2) and at the bottom (3).   3. Air filter for internal combustion engine,   according to one of claims 1 and 2, characterized in that   that the orifices (7 and 7 ') are arranged at a distance of 0.58 R at 0.68 R from the geometric center (11) of the body (1) of the air filter, where R is the radius of the body (1) of the air filter.   4. Air filter for internal combustion engine,   according to one of claims 1 to 3, characterized in that   the orifices (7 and 7 ') are closed by elements porous (8).