US3841278A - Engine cooling system - Google Patents

Abstract

1. IN AN AIR-COOLED ENGINE OF THE MULTICYCLE INTERNAL COMBUSTION TYPE HAVING A CYLINDER AND A COMBUSTION CHAMBER, AND INCLUDING AN INTAKE AND EXHAUST VALVE ARRANGED ONE BEHIND THE OTHER RELATIVE TO A STREAM OF COOLING AIR, THE IMPROVEMENT COMPRISING MEANS FORMING AN INTAKE CHANNEL IN THE HEAD OF SAID CYLINDER AND AN EXHAUST CHANNEL, SAID CHANNELS BEING SEPARATED, ONE FROM THE OTHER, AND FORMING AN AIR PASSAGEWAY THEREBETWEEN AND AT ONE SIDE OF SAID REARMOST VALVE, AND MEANS FOR DIRECTING COOLING AIR AROUND BOTH THE INTAKE AND EXHAUST VALVES, ALONG A LINE GENERALLY PARALLEL TO THE LINE OF SAID INTAKE AND EXHAUST CHANNELS, AND MEANS FOR DIVIDING THE STREAM OF COOLING AIR AROUND THE REARMOST VALVE TO PROVIDE AIR FLOW THROUGH SAID PASSAGEWAY AROUND SAID ONE SIDE OF SAID REARMOST VALVE AND AROUND THE OTHER SIDE OF SAID REARMOST VALVE, SAID DIVIDER ELEMENT BEING POSITIONED TO PROVIDE A SUBSTANTIALLY EQUAL FLOW OF AIR AROUND EACH SIDE OF THE REARMOST VALVE, SAID INTAKE CHANNEL TERMINATING WITH A CHARGE RECEIVING PORT, SAID PORT FACING IN A DIRECTION GENERALLY PERPENDICULAR TO SAID LINE OF COOLING AIR FLOW.

Description

United States Patent [191 Frehe V 111 3,841,278 45] Oct. 15, 1974 ENGINE COOLING SYSTEM [76] Inventor: Dieter Frehe, Avenue Edouard Herriot, Macon, Seine-et-Loire, France [22] Filed: July 14, 1971 [21] Appl. No.: 162,717

Related US. Application Data [63] Continuation-in-part of Ser. No. 842,886, July 18,

1969, abandoned.

[30] Foreign Application Priority Data July 22, 1968 Germany ..l75l747 [52] US. Cl. 123/4l.61, 123/4169 [51] Int. Cl. F021 l/32 [58] Field of Search 123/4l.6, 41.61, 41.69

[56] References Cited UNITED STATES PATENTS 3,650,250 3/1972 Lohr 134/4169 2,070,565 2/1937 Dintilhac 123/4l.61 2,140,397 12/1938 Alfaro 123/416 2,270,990 l/l942 Bachle 123/41.69 2,887,994 5/1959 Morris l23/41.69

FOREIGN PATENTS OR APPLICATIONS 1,930,148 6/1969 Germany ..123/4l.61 1,149,572 10/1960 Germany ..123/41.69

Primary Examiner-Charles J. Myhre Assistant Examiner-Barry Grossman Attorney, Agent, or Firm l-larrness, Dickey & Pierce H [57] ABSTRACT An air-cooled engine having an air flow directing system for guiding equal portions of cooling air around the intake and exhaust valves by means of the configuration of integrally cast portions of the cylinder head relative to the flow of cooling air.

The purpose of the foregoing abstract is to enable the Patent Office and the public generally, and especially the scientists, engineers 0r practitioners in the art who are not familiar with patent or legal terms ,or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by claims, nor is it intended to be limiting as to the scope of the invention in any way.

7 Claims, 2 Drawing Figures ENGINE COOLING SYSTEM This application is a continuation of U. S. Ser. No. 842,886, filed July 18, 1969, now abandoned.

BACKGROUND AND SUMMARY OF THE DISCLOSURE This invention relates generally to an air cooling system for internal combustion engines, and more particularly to a cooling system for an internal combustion engine having a combustion chamber provided laterally of the cylinder and wherein the exhaust valve is located behind the intake valve relative to the stream of cooling air flowing across the cylinder head. The cylinder head has been provided with integrally cast structural portions which are utilized to direct at least an equal portion of cooling air across the exhaust valve relative to the intake valve.

As is readily apparent in the case of air-cooled combustion engines, a critical factor in the operation, maintenance and production of engines of this type requires adequate and uniform cooling of the entire cylinder and cylinder head in the case of a single cylinder engine, or the plurality of cylinders and cylinder heads in the case of multicylinder engines. Not only does the heat gradient differ in individual regions of the cylinder and of the cylinder head, but additionally, the cooling influence of the surroundings and the stream of cooling air have different effects on the structural parts due to a variety of factors. Particularly, the exhaust valve region of the cylinder and cylinder head is under a substantially greater heat load, because of the hot exhaust gases, than the intake valve side due, in part, to the periodic cooling effect of the relatively cold fuel charge being introduced to the intake valve.

As a further consideration, the exhaust valve, in certain types of engines, is positioned downstream relative to the cooling fluid flow, from the intake valve section. Under these circumstances, the disadvantage exists that the intake portion of the cylinder and the cylinder head are cooled directly by a flow of cooling air which is heated by the intake before reaching the exhaust region. This is due, generally, to the fact that the cooling air is directed toward only one side of the cylinder and cylinder head, theair flow being caused in normal circumstances, by the velocity of travel of the driven vehicle or through the production of air flow by a cooling blower. These local differences in temperature cause great stresses in the cylinder and cylinder head and may, in certain circumstances, lead to cracking of the exposed structural parts. Thus, the efficiency of operation, and the useful life of the engine are decreased while increasing the cost of maintenance of the engine.

This situation has been cured, at least in part, through special design of cooling fins to obtain an increased cooling effect which are structurally complex and are expensive to manufacture. Particular problems occur from the standpoint of cooling technology in the situation of cylinders having an offset combustion chamber, the channels being necessarily disposed one behind the other. Thus, the engine further develops high hot spots at one side. In engines of this type, it is necessary to arrange the intake valve in front of the exhaust valve, relative to the stream of cooling air. Thus, the heat problem at the exhaust valve is greatly amplified.

With the system of the present invention, a simple and inexpensive method of uniformly cooling the exhaust and intake valve is provided while maintaining the structural features of the offset combustion chamber type of engine. The problem is particularly solved by the arrangement and formation of the region of the exhaust valve and its surrounding structure with respect to the cooling air such that the stream of cooling air flowing at the sides of the intake and exhaust valves, and around the cylinder, becomes relatively equally divided. Particularly, a first stream of cooling air is directed around the outside of the cylinder and also along the inner side of the exhaust channel and thus the exhaust valve, a second stream of cooling air flowing between the intake valve structure and the exhaust valve structure, and a third flow of air around the outer side of the exhaust structure.

In carrying out the features of the present invention, the region of the exhaust valve is turned toward the stream of cooling air valve side and includes an air catching and guiding nose, which engages and divides the stream of cooling air. The guiding nose generally projects toward the intake channel of the cylinder. This air catching and air guiding nose is constructed as a centrally disposed extension of the cylinder side wall at the exhaust channel and directed toward the stream of cooling air at the valve side and also extends substantially rearwardly relative to the stream of cooling air.

In evolving the configuration of the projection, the structure affects a dividing stream of cooling air at the valve sides in such a way that two streams of cooling air are generated which are generally equal in quantity, thus providing a substantially equal cooling effect for the two valve areas. It is possible that the structure may be so evolved as to direct a greater quantity of cooling air to the area of the exhaust valve, the exhaust valve generating a greater quantity of heat in that area.

With the system of the present invention, there is obtained a favorable direct cooling of the intake and exhaust valves, the system being inexpensive and simple to manufacture due to its being integrally cast with the cylinder head structure. Also the space required to achieve the structure of the present invention is relatively small. Further, it is possible for the intake and exhaust valves to be positioned very close to the cylinder wall due to the extremely efficient cooling of these areas. In this way, the chamber need not be made detrimentally long or flat and can more closely approximate an ideal spherical configuration. Thus, the more compact spherical configuration may be retained.

Accordingly, it is one object of the present invention to provide an improved air-cooled engine.

It is another object of the present invention to improve the cooling system for air-cooled engines.

It is another object of the present invention to provide an improved coolingsystem for an air-cooled engine wherein the exhaust valve area is cooled with a greater efficiency than heretofore known.

It is still another object of the present invention to provide an improved system for directing cooling air flow about the heat generating parts of an air-cooled engine.

It is still a further object of the present invention to provide an improved system for cooling the exhaust valve in air-cooled engines.

It is still a further object of the present invention to provide an improved cast structure for an air-cooled engine which enhances the cooling capabilities of the engine.

It is still a further object of the present invention to provide an improved cooling system for an air-cooled engine which is simple and inexpensive to manufacture.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims and the accompanying drawing in which:

FIG. 1 is a cross sectional view of a four-cycle, aircooled internal combustion engine incorporating certain features of the present invention, the section being taken through the intake and exhaust channels and valves and through the cylinder; and

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

For purposes of illustration of the invention, the aircooled internal combustion engine shown in the drawing is indicated as having a combustion chamber which is positioned laterally offset from the upper end of the cylinder. In this case, the valves, including the intake and exhaust valves are arranged alongside the projection of the cylinder wall and are utilized to control the flow of fluid between an intake and exhaust channel. However, it is to be understood that other types of engines may be utilized in connection with the features of the present invention.

Referring to the drawing, there is illustrated an aircooled engine 12 which includes, only a portion of the engine being illustrated, a cylinder wall 1 and a head assembly 13. It is to be understood that the remainder of the cylinder walls and piston are not illustrated in FIG. 1, and the entirety of the cylinder walls and piston are omitted from FIG. 2. The engine of FIGS. 1 and 2 includes a combustion chamber which is offset laterally from the upper end of the cylinder 1. Specifically, the combustion chamber is positioned directly below an intake valve 2, which valve seats on a charge receiving port, and an exhaust valve 3, which valves are arranged to be positionedto one side of the extension of the cylinder wall 1. The valves 2 and 3 are arranged to control the flow of fluid, particularly an air-fuel mixture, through an intake valve channel member 4, which is integrally formed with the head of the engine 12.

Similarly, the exhaust valve 3 is utilized to control the flow of exhaust gases within an exhaust channel 5, the exhaust channel 5 also being an integrally cast portion of the engine head 13. The engine is cooled by means of a centrifugal blower assembly 6, the blower includ ing a plurality of blade elements 14 which force the air from the exterior of the engine through the various portions of the engine for cooling. In order to enhance the cooling capabilities of the blower, a plurality of integrally cast fins 16 are formed in the head member to facilitate the removal of heat from said portions of the engine. It is to be understood that the cooling air flow could result from the movement of the engine in a driven vehicle.

The blower 6 propels a flow of cooling air across the various heat radiating portions of the internal combustion engine 12, and particularly, a stream is directed in a flow path 7 around the side of the cylinder which is away from the valves 2 and 3. Further, a flow path 8 of air is directed toward the intake and exhaust valves 2, 3 to cool the area adjacent the intake valve 2, intake valve channel 4, the exhaust valve 3 and the exhaust valve channel 5. The exhaust channel 5 is devised such that the stream of air 8 is divided into a stream 8a flowing between the cylinder wall 1, and the exhaust valve channel 5. A second stream 8b of air is directed between the intake valve channel 4 and the exhaust valve channel 5 and a third stream of air is directed around the outside portion of the exhaust valve channel 4, this latter stream being designated 80.

In the region of the outlet channel 5 which is turned toward the incoming cooling air, there is provided an air catching and guiding nose portion 9, which nose 9 is integrally molded with the head portion of the engine 12. The nose 9 engages the stream 8 of cooling air to valve channel 5, the nose dividing the stream 8 into the stream 8a and the stream 8b. The nose 9 is formed as an extension of the cylinder side wall 5a of the exhaust channel 5 and the nose 9 extends rearwardly relative to the blower 6. The nose 9 is devised such that an equal stream of air is caused to flow around the valve channels 4 and 5 so that the cooling effect of the air cools the valve channels 4 and 5 to an equal temperature, thus eliminating hot spots.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In an air-cooled engine of the multicycle internal combustion type having a cylinder and a combustion chamber, and including an intake and exhaust valve arranged one behind the other relative to a stream of cooling air, the improvement comprising means forming an intake channel in the head of said cylinder and an exhaust channel, said channels being separated, one from the other, and forming an air passageway therebe' tween and at one side of said rearmost valve, and means for directing cooling air around both the intake and exhaust valves, along a line generally parallel to the line of said intake and exhaust channels, and means for dividing the stream of cooling air around the rearmost valve to provide air flow through said passageway around said one side of said rearmost valve and around the other side of said rearmost valve, said divider element being positioned to provide a substantially equal flow of air around each side of the rearmost valve, said intake channel terminating with a charge receiving port, said port facing in a direction generally perpendicular to said line of cooling air flow.

2. The improvement of claim 1 wherein the exhaust valve is behind the intake valve and is raised to a higher temperature due to the exhaust gases, the improvement further comprising forming the cylinder to direct a larger quantity of air around the exhaust valve relative to the intake valve.

3. The improvement of claim 2 wherein the stream of cooling air around the exhaust valve is divided into two streams, the first stream flowing in said passageway between the intake and exhaust valve and the second stream flowing between the exhaust valve and the cylinder.

4. The improvement of claim 1 wherein the cooling air dividing means is formed as an air catching and air guiding nose projecting toward the incoming stream of cool air.

streams of air are directed around the exhaust valve and along the skirt elements.

7. The improvement of claim 6 wherein the skirt elements are formed integrally with the exhaust valve seat and form a heat radiator in the equal streams of air.

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