The invention relates to an air filter system for a reciprocating piston internal combustion engine with an air filter disposed in a filter housing connected to a clean air line extending to the engine air intake system and means for damping the air intake noise.
DE 23 42 154 A1 discloses a noise damping air filter element for reducing the air intake noise, in particular for compressors and air induction machines in which a two-component housing forms an ellipse in a longitudinal section, and in which two housing halves are each filled with open-pore PUR foam beyond the focal point of the ellipse and connected in a seal-forming fashion.
The total noise of a motor vehicle is mainly made up of the noise sources of the intake system, engine, exhaust system, power transmission system, chassis, fans and tires. In addition to the attention being paid both to reducing the noise emissions from the various noise sources of a motor vehicle attention is increasingly given to the damping of the noise generated by the air filter system at the air intake side. The noises generated in the internal combustion engines result essentially from engine vibrations, internal pressure pulsations and the combustion process. The intake noises, such as, for example, internal pressure pulsations which travel out of the engine and to the air filter through the air intake manifold, hot film air mass flow rate meter (HFM) and air lines, are usually damped by resonators and by a corresponding air filter volume. However, this damping is not sufficient and the wall of the air filter nevertheless emits noise which travels into the passenger compartment. So-called large-area voluminous mats of damping material are frequently used in the air filters in order to reduce or eliminate this kind of noise emissions. However, these have the disadvantage that they have to cover a relatively large area and are relatively expensive and space-consuming.
It is therefore an object of the present invention to provide an air filter system in which intake noises are damped within a relatively small space and which can be manufactured at comparatively little expenditures.
In an air filter system for an internal combustion engine comprising a fresh air line with an air inlet, a filter housing with an upper housing half and lower housing half, a filter element disposed in the filter housing, a clean air outlet opening with an adjoining clean air line opening into the intake system of the internal combustion engine, and means for damping intake noise, the means for damping the intake noise is configured and arranged in such a way that, on the other hand, the intake noise is absorbed by joint patch damping and, on the other hand, the intake noise is damped by a change in impedance, in particular by a jump in impedance.
In a particular embodiment of the air filter system, the means for damping or reducing noise is arranged on the side of the upper filter housing half disposed opposite the clean air outlet opening.
In an alternative embodiment, the geometric shape of the means for damping or reducing noise is adapted to the geometric shape of the upper filter housing half.
Preferably, the means for damping or reducing noise is composed of metal.
In one advantageous embodiment of the invention, the means for damping or reducing noise comprises a plate with a thickness of less than 1 mm.
Preferably, the surface of the plate is greater than, or at least approximately equal to, the surface of the clean air outlet opening.
Advantageously, the plate can be clamped against the wall of the upper filter housing half by means of a flow straightener.
Further features and advantageous embodiments of the invention will become apparent from the following description of the invention on the basis of the accompanying drawings:
a shows schematically a cross-section through an air filter which is not subjected to stress, and
b shows schematically a cross-section through an air filter which is subjected to stress (deformation).
Furthermore, the sandwich-like arrangement of material which reflects sound well and material which reflects sound poorly, i.e. the damping element 13 and filter wall 12 or flow straightener 15 at which a change in impedance ΔI, in particular a jump in impedance, occurs, also advantageously leads to a reduction in the noise level arising during operation of the engine due, for example, to pressure pulsations. Such an arrangement also exhibits high sound-reducing properties.
The principle of the damping of sound by an impedance jump ΔI is illustrated in
Both physical effects in conjunction with the shape and weight of the damping element 13 thus advantageously lead to a high, optimum sound-damping effect at the noise levels caused by intake noises, in particular by pressure pulsations. In addition to a low additional weight and to the small space required for installation, the metal plate 13 which is used for a damping element also advantageously incurs only low costs for procurement and installation in the air filter housing.
Number | Date | Country | Kind |
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10 2004 005 176.3 | Feb 2004 | DE | national |
10 2004 015 331.0 | Mar 2004 | DE | national |
This is a Continuation-In-Part Application of International Application PCT/EP2005/000854 filed Jan. 28, 2005 and claiming the priorities of German applications 10 2004 005 176.3 filed Feb. 2, 2004 and 102 004 015 331.0 filed Mar. 30, 2004.
Number | Date | Country | |
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Parent | PCT/EP05/00854 | Jan 2005 | US |
Child | 11496957 | Aug 2006 | US |