Air intake silencer

[0002] 1. Field of the Invention

[0003] The present invention relates to devices intended to reduce unwanted sounds created by internal combustion engines, and more specifically, to structure for decreasing the amount and intensity of sound produced by the air intake of such engines.

[0004] 2. Description of Related Art

[0005] Throughout the world, governments concerned with the spread of noise pollution have enacted or are considering enacting legislation and/or regulations aimed at lessening the amount and effect(s) of that pollution. Those efforts are, in part, directed at limiting sound energy emissions provided by internal combustion engines utilized in both small and large scale vehicles, including emissions produced by grounds-care equipment. To address the restraints imposed by this legislation on permitted emissions levels, industry has sought to reduce the level of noise associated with both the exhaust and air induction systems of these engines.

[0006] With regard to the air induction system of internal combustion engines, devices known as air intake silencers have often been used to muffle, and therefore reduce, the noticeability of sound energy caused by these engines. With air as the medium through which sound travels, silencers of this type assist in reducing sound energy created when air is introduced into the engine from the atmosphere. This is in opposition to exhaust systems whereby sound is produced as air exits the engine. This energy often takes the form of noise, the loudness of that noise corresponding to the chosen engine speed upon entry of air into the silencer.

[0007] The design of intake silencers has included structure composed of several components requiring connection by welding or other means. For example, one construction includes an open dampening shell having covers welded thereon at its ends. Thereafter, inlet and outlet piping is then attached, by additional welds, to the periphery of apertures provided in the covers for accommodating the flow of air through the shell. Although designs of this type have been capable of performing a silencing function, materials and construction costs remain as areas in which improvement can be viewed as advantageous.

[0008] Thus, in order to obtain an economically advantageous construction, there is provided a silencer formed as a one-piece structure. This structure is formed according to the principles of rotational molding thereby reducing the expense of fabrication. Preferably, the mold will be constructed of plastic in the form of cross-linked polyethelene. Alternatively, composite materials could be substituted.

[0009] To permit air flow into an engine of vehicle, the silencer is constructed of a main body equipped with an inlet to which suitably fitting tubing can be attached to direct air into the inlet. Paralleling the inlet on an opposing side of the silencer is an outlet through which air is delivered to the engine. Those of ordinary skill in the art will recognize that designation of the inlet and outlet may be interchanged.

[0010] Forming the above inlet and outlet are two pipe-like formations molded as part of the overall silencer body. These formations are laterally spaced apart from one another and are substantially similar in the preferred embodiment. Formation of each of the inlet and outlet pipes in this manner enables the main body to be formed from a single mold while also creating an air flow path through the main body. Optimum silencing effect may be achieved by tailoring the dimensions and thus, the volume, of the main body to the engine with which the silencer is to be used. Such tailoring will permit an adequate and appropriately sized flow path so that as air is introduced into the engine during operation, the engine is not starved of air, thereby avoiding engine stall. It is contemplated that the silencer of the instant invention may be used with an engine equipped with either a carburetor or injector fuel delivery system.

[0011] Further delivery of air to the engine is accomplished by travel through additional tubing connected to the outlet and to an attached air filter flowing to the engine.

[0012] Thus, there is provided a simple and economical air intake silencer allowing for the introduction of air into a vehicle engine while silencing the effect of that entry.

[0013] FIG. 1 is a front perspective view of the silencer of the present invention connected with an air filter.

[0014] FIG. 2 is an exploded view corresponding to the illustration of FIG. 1.

[0015] FIG. 3 is a top perspective view of the silencer according to the present invention and illustrating the inlet of the silencer.

[0016] FIG. 4 is a cross-sectional view taken along lines 4—4 of FIG. 3 illustrating an outline of the silencer.

[0017] Looking at FIGS. 1-2, there is illustrated the silencer 10 of the instant invention which may be arranged within and connected with an internal combustion engine (not shown). Further, it can be seen that air is to be directed into the silencer body 10 through a length of tubing 12 having, preferably, a tapered end 14 and a rounded end 16. Connected with the rounded end 16 is an inlet pipe 18 of silencer 10 set within a pocket 20 extending downwardly from a top surface 22, as best seen in FIG. 3. Spaced from inlet 18 is a first concave surface 24 formed within top surface 22. This concave 24 provides structural rigidity to silencer 10. On a bottom surface 26 is formed a pocket 28, and an outlet pipe 30, formed within the pocket 28 which is similar to pocket 20, through which air travels toward the engine. With like appearance as to top surface 22, a second concave surface 32, shown in FIG. 4, is formed across from outlet 30 on bottom surface 26.

[0018] Returning to FIGS. 1-2, it will be seen that silencer 10 is connected to an air filter 34 by a tubular elbow 36 at outlet 30. As air travels through filter 36, it is then directed toward engine 12 by an intake pipe 38.

[0019] Shown in FIG. 4 is a cutaway view of silencer 10 taken along lines 4—4 of FIG. 3. This view illustrates the interior flow path and silencer structure relative to a generally cylindrical side surface 40. As can be seen, the inlet 18 and outlet 30 take the form of generally cylindrical tubes having therein respective end portions within the silencer overlapping one another. Accordingly, an interior end portion 42 of inlet 18 is located close to bottom surface 26 while an end portion 44 of outlet 30 is located closer to top surface 22. Together with pockets 20 and 28, parallel extension of inlet 18 and outlet 30 relative to each other in this manner serves to define an air path depicted by the directional arrows A provided in FIG. 4.

[0020] Flow of air through the silencer 10 is as follows. Air is first introduced into the engine (not shown) during its operation through tubing 12 wherein it then flows into silencer 10 via inlet 18. Upon movement beyond inlet 18, the stream of air is then smoothed upon encountering convex surfaces or deflectors 46, 48 which are opposite concave surfaces 32 and 24, respectively, on an interior of the silencer 10. After impacting deflector 46, the stream is then caused to flow through a channel 50 for delivery into outlet 30, where it then exits the silencer 10 and proceeds toward the engine.

[0021] Reduction of sound energy, in the form of noise resulting from the engine's operation, is attributable to at least two factors. First, silencer 10 is a reactive type silencer wherein a portion of sound produced by the engine enters the silencer 10 and is then reflected back towards the engine. This reflection back is caused, significantly, by the structural mold of the interior of the silencer 10. Accordingly, a large portion of sound does not radiate outwardly away from the engine toward the atmosphere. Secondly, sound traveling through the interior of the silencer 10, and outwardly toward the atmosphere, as shown by the directional arrows B in FIG. 4, is dampened in terms of its acoustic intensity. This dampening, as well as the reflection back mentioned above, is caused by the indirect path created by the convergence of inlet 18 and outlet 30 at channel 50 and shown by the arrows B in FIG. 4, in which sound must travel as it leaves the silencer 10. Travel along this path B provides an opportunity for a dampening of sound energy which is not reflected back toward the engine. As this dampening occurs, the level and intensity of sound emitted from the silencer 10 is decreased, thereby resulting in a less noticeable and more tolerable degree of noise emitted into the environment.

[0022] While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.