Internal combustion engine having a sound-muffling casing

Abstract

An internal combustion engine having a casing surrounding said engine for muffling the sound generated therefrom. The casing is composed of a plurality of sound muffling plates which are adjusted in their shape to the shape of the engine housing. Each of the plates is releasably connected to one another to facilitate ready access to the engine. A support plate is provided on the engine to which the remaining sound muffling plates are releasably secured.

Description

FIELD OF THE INVENTION

The invention relates to an internal combustion engine having a casing which functions as a sound-muffling device and fully encloses the engine housing.

BACKGROUND OF THE INVENTION

The purpose of the present invention is to produce a casing which can be manufactured economically, which can be easily adapted to the type and size of an engine and can be removed quickly for maintenance purposes. This purpose is achieved according to the invention in such a manner that the casing consists of several sound muffling or dampening plates having a shape which is adjusted to the shape of the engine housing, which plates are releasably connected with one another, and that between two adjacent parts of the engine housing a support plate is clamped tightly, on which support plate the adjacent sound muffling or dampening plates are releasably secured.

In the preferred embodiment of the invention, the arrangement is such that between the support plate and the soundmuffling or dampening plates at least one intermediate bar of sound-muffling material, preferably rubber is provided, and that for securing the muffling plates on the support plate, releasable locks, preferably snap locks, are used.

According to a different inventive characteristic, it is advantageous to arrange the support plate between the cylinder head and the valve cover which sits on same for the rocker arms and through this structure, the inside of the casing is divided into two separate chambers. This arrangement permits a division which is particularly useful for maintenance purposes in that an air filter is provided in the space above the support plate and said space has an air inlet.

According to a further characteristic of the invention, several openings are provided in the muffling or dampening plate facing the bottom of the engine, through which openings project the feet secured on the engine housing, and that the openings are closed off against the inside of the casing by means of intermediate rings of sound-muffling material, preferably rubber.

A simplification and space saving of a special type results according to a different inventive characteristic by having one of the sound-muffling or dampening plates carry the structure defining a fuel tank or at least partially form same.

BRIEF DESCRIPTION OF THE DRAWINGS

One exemplary embodiment of the invention will be described more in detail in the following description with reference being made to the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional view of the internal combustion engine with its casing,

FIG. 2 is a cross-sectional view taken along the line II--II of FIG. 1,

FIG. 3 is a top view of the support plate secured on the engine, and

FIGS. 4 and 5 illustrate some details of the casing.

DETAILED DESCRIPTION

The exemplary embodiment illustrates a one-cylinder, air-cooled fuel-injection internal combustion engine of a known type which is composed of a crankcase 10, a vertical cylinder 12 and a cylinder head 14. In a bearing cover 16 there are positioned the not illustrated rocker arms and are closed off by a cap 18. The cylinder head 14 and the cylinder 12 are clamped tightly, by means of screws 20 which engage threaded holes in the crankcase 10, with said crankcase 10. The valve cover assembly 16 with the cap 18 is anchored on the cylinder head 14 by means of screws 22.

A square support plate 24 is placed on the flat head surface of the housing part 14, the thickness of which support plate is several millimeters and which support plate assures the required stability. The plate 24 will be made of thin metal plate having exact dimensions so that both height and plane parallelism of the support surfaces are assured. It is therefore possible without influencing the true measurement to permit the valve cover assembly 16, 18 to sit on the support plate 24. The screws 20, 22 take thereby care of the connection of the support plate 14 with the engine housing.

The plate 24 is used as a carrier of a casing which fully surrounds the engine body for the purpose of muffling the created noises. An intermediate bar 26 of rubber is mounted, for example, glued, on the periphery of the support plate 24 and forms a sound-muffling support for four approximately vertically positioned sound-muffling plates 30, 32, 34, 36 which are shaped to the shape of the engine and one inverted cup-shaped sound-muffling shell 38 which is mounted as a lid over the entire structure. A plurality of snap locks 40 are secured to the vertically positioned muffling plates and engage behind a flanged peripheral edge of the inverted muffling plate 38 to connect in a secure manner all muffling plates with the support plate 24. Thus the casing can be easily mounted on the engine and can quickly be removed for maintenance purposes. The plates may be connected additionally, if desired, at some points by screws 42 (FiG. 4) if this should be required for example in the case of larger engines to secure the compactness of the casing.

The casing is closed off against the bottom 44 by a sound-muffling plate 28 which is also connected by a plurality of screws 42 to the vertical plates. In order that the weight of the engine not be transmitted through the plate 28, a plurality of openings 28a (FIG. 5) are provided therein. A foot 46 entends through each opening 28a, which foot is on one side screwed to the underside of the crankcase and on the other side bears on the bottom 44. An annular, sound-muffling intermediate layer 48 of rubber is fixedly connected to two annular plates 48a, 48b, for example, by means of welding. The plate 48b is during installation secured to the foot 46 on the crankcase 10, while the muffling plate 28 is anchored, for example riveted, to the plate 48a.

The muffling plate 34 is at the same time constructed as a carrier of a fuel tank 50, the back portion 50b of which is mounted on the plate 34, for example by riveting, An opening 50a functions as a neck into which the fuel is placed, while a line which is not further illustrated within the casing leads to the injection nozzle 52 positioned in the cylinder head 14.

It is also mentioned that at least in some muffling plates openings must be provided through which the operating elements, such as the accelerator connections, electrical connections, exhaust ports and the like of the internal combustion engine extend to the outside in a manner as is for example discussed in detail in the Offenlegungsschrift No. 2,159,158. The extension of an operating shaft 54 and its associated opening is, for example, indicated in FIG. 2. Furthermore, it is pointed out that the space within the lid 38 must be equipped in a suitable manner with an air inlet to permit the admission of air to an air filter mechanism 56 which is arranged in this space and is positioned adjacent the intake port 58 of the engine. The port extends through an opening 24a in the support plate 24 upwardly into the space beneath the lid 38. Also the injection nozzle 52 extends through an opening 24b in the support plate into said space. The exhaust manifold 60 is for example guided outwardly through an outlet in the muffling plate 36.

In engine constructions having a cooling air blower, it is possible, differing from the aforementioned supply of the engine with combustion air, to make the arrangement also in such a manner that, for example from the not illustrated blower, fresh cooling air is conveyed through an inlet opening 34a in the plate 34 into the inside of the casing. A portion of this amount of air reaches the filter 56 through the openings 24a and 24b in the support plate 24 and is used as combustion air. (One opening in the lid 38 is cancelled in this case). The other portion of the amount of air is guided within the casing over the cooling ribs on the periphery of the cylinder 12, through cooling channels in the cylinder head 14 and around the crankcase 10, as this is indicated by the arrows illustrated in FIG. 1. This cooling air cools sufficiently the housing parts 10, 12, 14 of the internal combustion engine and exits to the outside as warm discharge air for example through an outlet port 30a in the plate 30. It is also mentioned that the outlet port 30 a is constructed as a so-called sound dampening stretch, namely that it is lined on the inside for the purpose of absorbing sound with sound-muffling layers.

In view of the fact that the absorbing plates are not exposed to any excessive stress, they are for example manufactured of plastic. Of course a different material, for example steel plate, can be used for the same purpose. The shape of the support plate 24 can easily be adjusted to the engine construction. For example in the case of a multi-cylinder in-line engine, one single support plate is used over the entire blank of cylinders. The same adjustment can also be achieved with the elements of the casing.

Although a particular preferred embodiment of the invention has been disclosed for illustrative purposes, it will be understood that variations or modifications thereof which lie within the scope of the claims are fully contemplated.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination with an internal combustion engine having at least two mating part and fastening means for fastening said two parts together, a sound-absorbing casing completely enclosing said engine, comprising:

a support plate positioned and secured between said two parts when said two parts are fastened together by said fastening means, said support plate extending laterally outwardly from the walls of said internal combustion engine;

a plurality of sound-muffling plates releasably connected together to define a casing having an open side thereon, said internal combustion engine being received in said casing;

releasable securing means for releasably securing said casing adjacent the edges of said open side to said support plate; and

vibration damping material located between said support plate and said sound-muffling plates and encircling the periphery of said open side, said casing being supported solely by said support plate through said releasable securing means and said vibration damping material.

2. A sound-absorbing casing according to claim 1, wherein said two parts are two adjacent parts of a housing defining said engine; and

wherein said support plate is clamped in its position between said two parts by the same clamping means that clamps said two adjacent parts of a housing defining said engine together.

3. A sound-absorbing casing according to claim 1, including a cover also releasably secured to said support plate over said open side by said fastening means;

wherein said two parts are a cylinder head and a valve cover for said internal combustion engine, whereby said support plate divides the interior of said sound-absorbing casing and said cover into two separate chambers.

4. A sound-absorbing casing according to claim 3, wherein in the chamber defined by said cover and said support plate encloses an air filter attached on an air suction pipe of the engine, said pipe passing through an opening in said support plate, and said chamber defined by said casing and said support plate having at least one air inlet port and at least one outlet port.

5. A sound-absorbing casing according to claim 1, wherein in said sound-muffling plates facing a bottom surface of said engine, several openings are provided through which project the feet which are secured on the engine housing, and that the openings are closed off against the interior of said sound-absorbing casing by means of intermediate rings of sound-muffling material.

6. A sound-absorbing casing according to claim 1, wherein one of said sound-muffling plates has means defining a fuel tank thereon.

7. A sound-absorbing casing according to claim 1, wherein one of said sound-muffling plates define at least a portion of a fuel tank.