US3762497A

US3762497A - Air cooled internal combustion engine with noise reducing means

Info

Publication number: US3762497A
Application number: US00243164A
Authority: US
Inventors: E Hatz; J Schmuck
Original assignee: Motorenfabrik Hatz GmbH and Co KG
Current assignee: Motorenfabrik Hatz GmbH and Co KG
Priority date: 1971-04-22
Filing date: 1972-04-12
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

An air-cooled internal combustion engine is provided with noise reducing means without increasing space requirements. A blower is provided to direct cooling air to at least one engine wall, for example a cylinder wall, and an engine accessory such as a fuel tank, which is needed in any event, forms a conduit to convey cooling air away from the engine wall. The cooling air path is lined with noise absorbing material, such as rock wool, held in position by a foraminous sheet. Where the blower impeller is rotatably mounted on a fixed shaft, similar noise reducing means can be provided on the shaft on the downstream side, the upstream side, or both, of the impeller.

Description

1 r Unite States atent 1 1 m1 3,762,497 Hatz et a1. 1 Oct. 2, 1973 AIR COOLED INTERNAL COMBUSTION 3,601,101 8/1971 Thien et .11 181/33 K x NG WITH NOISE REDUCING MEANS 3,684,053 8/1972 Thicn ct a1 i 181/33 [75] Inventors: Ernst Hatz, Ruhstorf; Johann FOREIGN PATENTS OR APPLICATIONS Schmuck, Feilnbach, both of 761,751

Germany Assignee: Motorenfabrik llatz KG, Ruhstort,

Germany Filed: Apr. 12, 1972 Appl. No.: 243,164

6/1967 Canada 181/33 K Primary ExaminerRichard B. Wilkinson Assistant Examiner-John F. Gonzales Attorney-Roberts B. Larson et a1.

[57] ABSTRACT An air-cooled internal combustion engine is provided with noise reducing means without increasing space requirements. A blower is provided to direct cooling air to at least one engine wall, for example a cylinder wall, and an engine accessory such as a fuel tank, which is needed in any event, forms a conduit to convey cooling air away from the engine wall. The cooling air path is lined with noise absorbing material, such as rock wool, held in position by a foraminous sheet. Where the blower impeller is rotatably mounted on a fixed shaft, similar noise reducing means can be provided on the shaft on the downstream side, the upstream side, or both, of the impeller.

8 Claims, 4 Drawing Figures AlllR COOLEID INTERNAL COMBUSTION ENGTNE WlITH NOISE REDUCING MEANS BACKGROUND OF THE INVENTION The invention relates to an internal combustion engine with a cool air blower and with an arrangement for damping the noises occurring.

It has been known to damp noises radiating from the engine elements by coating, encasing, etc. The walls in the cool air inlet and outlet however limit the openings that cannot be closed, so that here the damping or sliencing means can be housed only in a cumbersome and expensive manner.

It is an object of the present invention to avoid the foregoing disadvantages and to provide an arrangement for noise reduction which requires only a small space and at the same time can be constructed of very simple, economically producible elements.

BRIEF SUMMARY OF THE INVENTION The foregoing and other objects which will be apparent to those of ordinary skill in the art are achieved according to the present invention by disposing the noise absorbing means both between the blower and the wall of the engine facing it, for example a cylinder wall, as well as on the other side of the engine wall. An engine accessory available per se, such as a fuel tank, is used to form a housing for the noise reducing means on the side of the cylinder remote from the blower. The damping or sliencing means preferably comprises a layer made of a soundproofing raw material, for example rock wool, surrounding the stream of cooling air, and this layer is held on the side of the stream of cooling air in a sieve-like mounting including a foraminous sheet.

In the case of blower having a locally fixed bearing shaft for the impeller of the blower and with a cylindrical housing surrounding it, according to another embodiment of the invention the sieve-like mounting with the soundproofing layer is attached on the shaft between the impeller and the engine wall facing it. In order to enlarge the damping path, an additional similar sieve-like mounting with a soundproofing layer may be additionally attached on the shaft in front of the impeller.

Another increase of the damping effect will result according to another characteristic of the invention through the fact that a sieve-like mounting with a soundproofing layer also is mounted on the inside wall of the blower housing. in this case the blower housing together with the sieve-like mounting can be supported either by the engine housing or by a sieve-like mounting on the shaft.

In a particularly favorable embodiment of the invention the engine part utilized to convey cooling air away from the engine wall facing away is developed as a fuel tank with a passage for the cooling air. The inside wall of the passage likewise is provided with a soundproofing layer in a sieve-like mounting.

DETAIILED DESCRIPTION There follows a detailed description of a preferred embodiment of the invention, together with accompanying drawings. However, it is to be understood that the detailed description and accompanying drawings are provided solely for the purpose of illustrating a preferred embodiment and that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

FIG. 1 is a longitudinal schematic section view through an internal combustion engine and showing noise reducing means in the stream of cooling air;

FIG. 2 is a cross section view through the fuel tank following line II-II of FIG. ll;

FIG. 3 is a view like FIG. 1 showing another embodiment of the noise reducing means on the blower; and

FIG. 4 is a view like FIG. 2 showing a different arrangement of noise reducing means in the fuel tank.

FIG. 1 shows a one-cyliner, air cooled internal combustion engine of a known construction with an engine crank housing 10, a perpendicular cylinder 12 with cooling ribs 12a attached to the periphery as well as a cylinder head 14 with horizontal air cooling channels 14a. The cool air blower includes an impeller ll6 with blades 116a attached to the periphery, and a bearing shaft 18 fixed in cylinder head 14 serves for the mounting of impeller 16. Blades are surrounded by a cylindrical housing 20, which is attached to crank housing It) by means of a few screws 22. The drive of impeller 16 is accomplished via belt 24 from the crank shaft which is not shown.

On the side of the internal combustion engine opposite the blower, a fuel tank 26 has been attached close to cylinder 12, whereby it is held on a flange 10a of crank housing 10 by means of screws, which are not shown. Tank 26 has a passage 26a (FIG. 2) for the cooling air which is U-shaped in its cross section. In this manner the cooling air, sucked in by the blower mechanism on the front side of housing 20 and passing the areas of cylinder head 14 as well as cylinder 12 that are to be cooled, can emerge again through opening 26a within tank 26, as the arrows in FIG. ll indicate.

An annular mounting 28 made of sheetmetal is attached to the shaft 18 between impeller 16 and cylinder head 14, for example by being forced on the axle. The connection of the parts of the mountings among one another-is accomplished in a suitably known manner, for example, by flanges. Inside mounting 28, a layer 30 of rock wool has been placed as a silencing agent, and the sieve-like surrounding wall 28a makes possible the access to the sound damping agent inside the mounting 28. A similar annular mounting 311, 310 with rock wool filling 33 is also attached in front of impeller 16 on shaft 18. Finally, a filling 34 made of rock wool is also provided inside blower housing 20 and is held by means of a sieve-like mounting 36.

The exit opening 26a on the opposite side of the cylinder is provided in the same manner with a layer 38 of rock wool which layer is held in position by means of a sieve mounting an of a rectangular cross section (FIG. 2) relative to the stream of cooling air. At the same time, this arrangement is made in such a way that the sound absorbing material 38, 4'11) inside tank 26 is invisible from the outside.

It is obvious that as a result of the silencing layer 30 inserted between impeller 16 and cylinder head M and the silencing layer 38 inside fuel tank 26 and likewise extending up to cylinder 12, the damping path is considerably enlarged both on the inlet and on the outlet side of the stream of cooling air without there being any requirement for additional space for the damping agents in the engine. The spaces for accessory, which exist in the engine anyway, thus are used in a particularly advantageous manner for the housing of the damping means, which results in a considerable increase of the damping effect with a simultaneous unchanging space requirement of the engine. The damping layers consequently can be inserted not only in the case of new engines but they also can be inserted in existing internal combustion engines or they can be created by replacing the fuel tank.

Since the sieve mountings with rock wool filling do not rotate, the layering of the damping agent is not disturbed by the centrifugal force. Therefore no unbalancing can occur in the damping agent. Moreover, no crumbling and gradual loss of the mass occurs under any circumstances in the fixed damping agent. Finally, the damping layers assure a sufficient annular gap in the blower and therefore in no way affect the stream of cooling air. The sieve-like mountings therefore can be moved close to adjacent parts (drive belt, impeller) without impeding the degree of effectiveness of the blower by these damping agents or undesirable noise developing because of the flow impediment. In the drawing the perforations in the sieve-like mountings have been indicated only roughly for reasons of clarity. In reality these mountings however have a large number of perforations, which result in a finely meshed mounting sicvc and thus in easy access to the damping agents.

The arrangement of the silencing agent on the blower also can be made according to FIG. 3 in a modified manner. In this case the blower housing 20f is not attached to engine housing but it is carried directly by the front mounting 31 by way of a few radial ribs 42. The

parts

31, and 42 thus are developed in one piece. The wall in this case thus serves merely as a support surface for housing 20' carried by shaft 18.

Let it also be mentioned that the outlet opening 26a inside fuel tank 26 could be subdivided in case of need by one or more separating walls in mounting 40 with the same rock wool filling and thus an additional increase in silencing could be achieved. In the case of a sufficient width of exit opening 26a, naturally the sievelike mounting 40' can be kept open on one side, as FIG. 4 shows.

It will be clear that the engine accessory, such as fuel tank 26, which is used to form a conduit for conveying cooling air away from the engine is one which is essential to operation of the engine for some other purpose. Thus, the engine part has an essential function other than for conveying cooling air and for providing a location for the noise reducing material positioned downstream of the engine.

What is claimed is:

1. In an air-cooled internal combustion engine having blower means for moving an air stream for cooling at least one engine wall and having means for reducing the noises caused by moving engine elements, the improvement wherein: an engine accessory is utilized to form a coolant air exit conduit for conveying cooling air away from said engine wall; said blower comprises an impeller mounted on a fixed shaft extending between said blower and said engine wall; a layer of noise absorbing material is positioned on said fixed shaft between said impeller and said engine wall and surrounding said shaft; and a noise absorbing material is positioned adjacent the cooling air path on the inside of the exit conduit formed by said engine accessory.

2. An improved air cooled internal combustion engine according to claim 1 wherein said noise absorbing material is in the form of a layer surrounding the cooling air path.

3. An improved air cooled internal combustion engine according to claim 1 wherein said noise absorbing material comprises rock wool.

4. An improved air cooled internal combustion engine according to claim 1 wherein said noise absorbing material is held in position by mounting means comprising a foraminous member.

5. An improved air cooled internal combustion engine according to claim 1 wherein a further layer of noise absorbing material is positioned at the air intake side of said blower on and surrounding said shaft.

6. An improved air cooled internal combustion engine according to claim 5 wherein said layer and further layer of noise absorbing material are held in posi tion by mounting means comprising a foraminous member.

7. An improved air cooled internal combustion engine according to claim 1 wherein said blower includes an impeller rotatably mounted within a housing, wherein said engine includes an engine housing, and wherein said blower housing is secured to said engine housing.

8. An improved air cooled internal combustion engine according to claim 1 wherein said engine accessory comprises a fuel tank.

Claims

6. An improved air cooled internal combustion engine according to claim 5 wherein said layer and further layer of noise absorbing material are held in position by mounting means comprising a foraminous member.