US3139870A

US3139870A - Internal combustion engines with four valves

Info

Publication number: US3139870A
Application number: US164102A
Authority: US
Inventors: Sampietro Achille Carlo
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-01-03
Filing date: 1962-01-03
Publication date: 1964-07-07
Anticipated expiration: 1981-07-07
Also published as: GB960396A

Description

y 7, 1954 A. c. SAMPIETRO INTERNAL COMBUSTION ENGINES WITH FOUR VALVES Filed Jan. 3, 1962 4 Sheets-Sheet 1 ATTORNEY y 7, 1964 A. c. SAMPIETRO 3,139,870

INTERNAL COMBUSTION ENGINES WITH F OUR VALVES Filed Jan. 5, 1962 4 Sheets-Sheet 2 A TTORA/E Y u y 1964 A. c. SAMPIETRO 3,139,870

INTERNAL COMBUSTION ENGINES WITH FOUR VALVES Filed Jan. 5, 1962 4 Sheets-Sheet 3 A TTOR/VE Y y 7, 1964 A. c. SAMPIETRO 3,139,870

INTERNAL 'CQMBUSTION ENGINES WITH FOUR VALVES Filed Jan. 3, 1962 4 SheetsSheet 4 A TTORA/E Y United States Patent F 3,139,870 INTERNAL COMBUSTION ENGINES WITH FOUR VALVES Achille Carlo Sampietro, 60 Martell Drive, Bloomfield Hills, Mich. Filed Jan. 3, 1962, Ser. No. 164,102 8 Claims. (Cl. 123-32) The present invention relates to internal combustion engines and provides improved cylinder head arrangements for such engines.

An object of the invention is to provide improved valve rocker arm mountings and improved cam arrangements which permit favourable location of the valves and injectors or spark plugs.

A further object is to provide an internal combustion engine with valves so disposed as to permit favourable location of the injectors or spark plugs from the point of view of obtaining good combustion efiiciency.

Further objects and advantages of the invention will become apparent from the following description of preferred embodiments of the invention given by way of example only, and to be read in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a plan of a cylinder head unit according to one embodiment of the invention;

FIG. 2 is a section on the line II-II of FIG. 1;

FIG. 3 is a section, partly cut away, on the line IIIIII of FIG. 1;

FIGS. 4 and 5 are views of alternative supports for the valve rocker arms of the unit shown in FIGS. 1 and 2;

FIG. 6 is a diagrammatic plan of an alternative cylinder head unit according to the invention, some parts being omitted for greater clarity;

FIG. 7 is a section, partly cut away, on the line VII-VII of FIG. 6;

FIG. 8 is a section on the line VIIIVIII of FIG. 6; and

FIG. 9 is a plan of an alternative form of rocker arm for the unit shown in FIG. 6.

The drawings show cylinder head units for compression ignition engines, but the invention may be applied equally to spark ignition engines the spark plug being placed in the same position as the injector.

In the drawings, the invention is shown as applied to only one cylinder head unit, but the invention may be applied to engines with more than one cylinder.

Referring to FIGS. 1, 2 and 3 of the drawings, a cylinder head 1 formed with a combustion chamber 10 having a fiat upper surface is provided with two identical circular inlet ports 2 and two smaller identical circular exhaust ports 3. The inlet ports 2 are symmetrically located with respect to the cylinder head 1 on opposite sides of a central plane of the cylinder head extending transversely of the longitudinal axis of the engine. The centres of the inlet ports 2 are on the same side of a central plane of the cylinder head which is normal to the above-mentioned transverse plane and extends longitudinally of the engine. The present engine has a number of cylinders (only one of which is shown) located in line along its central longitudinal plane.

The exhaust ports 3 are also located on opposite sides of said transverse plane in symmetrical positions with respect to the cylinder head 1. The centres of the exhaust ports 3 are on the opposite side of said longitudinal plane from the centres of the inlet ports 2.

An injector 6 is located between the four

ports

2, 2 and 3, 3 near the central axis of the cylinder head 1 and combustion chamber. The injector 6 may be in some cases offset slightly towards the smaller exhaust ports so that no excessively narrow and therefore weak neck of 3,139,870 Patented July 7, 1964 metal is formed in the cylinder head. By arranging the injector between four valves, a position is achieved for it which is beneficial from the point of view of achieving proper mixing of the fuel and the air to achieve combustion efliciency and fuel economy.

In the case of a spark ignition engine, the spark plug is located at the same position as the injector 6 in the present engine with similar beneficial results in achieving combustion efliciency.

The valve stems of inlet and

exhaust valves

14 and 15 respectively of the present engine are disposed parallel to one another and to the central axis of the cylinder head 1.

For operating the valves and the injector 6 of the present engine a camshaft 8 is provided and is journalled in bearings mounted in lugs such as that shown at 7 in F IG. 1. A single camshaft 8 extends across all the cylinder head units of the engine and operates all the valves and injectors. The present invention thus enables important savings to be made in the number of parts required for the engine while at the same time providing the advantages of an overhead camshaft with a simpler construction than those employing two camshafts.

The camshaft 8 extends in the longitudinal direction of the engine, i.e. parallel to the line of cylinders, and is provided with three

cams

11, 12 and 13 to operate the valves and the injector respectively.

The camshaft 8 is also provided with similar cams to operate the valves and injectors of each of the other cylinders.

The

cams

11 and 13 are identical in shape and have the same angular position on the camshaft 8 and each is arranged to operate one of the exhaust valves 14 and one of the inlet valves 15.

A separate rocker 16 is provided for operating each exhaust valve 14. In this embodiment the rockers 16 are made of channel-shaped metal but alternative shapes may be used. The rockers 16 are supported for rocking movement on a rod 17 extending parallel to the camshaft 8 and mounted in the lugs 7 which support the camshaft.

One end of each rocker 16 is provided with an abutment 22 which engages the top of the corresponding valve stem 23. At the other end, each rocker 16 is provided with a roller 24 to engage the

cam

11 or 13.

Each exhaust valve stem 23 is urged upwardly by a coil spring 25 located on the valve stem and engaged under a disc 26 secured on the valve stem. The lower end of the spring 25 is engaged against the cylinder head 1.

Since the abutment 22 on the rocker 16 is urged upwardly, the end of the rocker carrying the roller 24 is urged downwardly and the roller 24 is thus urged into contact with the

corresponding cam

11 or 13. As the camshaft 8 rotates and the raised portions of the cams come under the rollers 24, the rollers will be forced upwardly and the abutments 22 will be forced downwardly thus opening the valves 14.

A separate rocker 31 is provided for operating each inlet valve 15 and is also made of channel-shaped metal. Each rocker 31 is formed near one end with an inwardly projecting, i.e. re-entrant, part-spherical seat 32 the outer, i.e. concave, surface of which is engaged on a part-spherical end portion 33 of an elongated member constituted by a stud 34. The stud 34 is screwed into a socket in the cylinder head 1 and secured with a lock nut 39. At the end remote from the seat 32, each rocker 31 is formed with an abutment 35 which engages the top of the valve stem 36 of the corresponding valve 15. Each valve 15 is urged upwardly by a spring 37 engaged under a disc 38 secured on the valve stem 36.

Each rocker 31 carries a roller 41 at a position intermediate its ends. The roller 41 engages with the

corresponding cam

11 or 13 and is forced downwardly to open the valve 15 when the raised part of the cam comes in contact with the roller.

The injector 6 is operated by a channel-shaped metal rocker 42 one end 43 of which is secured to the stem 44 of the injector. At the other end, the rocker 42 is provided with a roller 45 which is in engagement with the cam 12. The rocker 42 is mounted for rocking movement on the rod 17 between the two rockers 16.

In a spark ignition engine, the rocker 42 and the cam 16 would be omitted.

Referring to FIGS. 4 and 5, there are shown alternative mountings for the two rockers 16 and for the rocker 42. The rockers 31 are mounted in the same way in the two constructions, but the rockers 31 shown in FIG. 5 are a slightly different shape from those shown in FIGS. 1 and 2.

Each rocker 16 in the alternative construction is mounted for rocking movement on a part-spherical end portion 4 of an obliquely downwardly projecting elongated member constituted by a rod 5. The rod 5 is fixedly secured to a part (not shown) rigid with and above the cylinder head I.

The end portion 4 is engaged in a part-spherical seat 9 formed in the bottom of the channel-shaped rocker 16.

One advantage of this form of mounting for the rockers 16 is that the rods 5 are subjected substantially to only longitudinal stresses and are thus better able to resist deflections than the rods 17 in the mounting shown in FIGS. 1 and 2.

In order to enable a similar alternative mounting to be adopted for the rocker 42, which is located between the two rockers 16, and at the same time to ensure that no part of the rocker 42 or its support will foul the inlet valves, the construction shown in FIG. 4 is adopted. In this construction, the rocker 42 is formed with a partspherical re-entrant portion 46 and the rocker is supported for rocking movement by engagement of the re-entrant, i.e. convex, face of the portion 46 with a part spherical re-entrant end of an obliquely downwardly projecting rod 47.

The rocker 42 is formed at one end with an abutment 43 to engage the top of the stem 44 of the injector and is provided at the other end with a roller 45 to engage the cam 12.

The embodiment shown in FIGS. 6 to 8, again has a number of cylinders and on each cylinder head valve rockers 50 are arranged to radiate from the central axis of the combustion chamber and the valves are operated by earns 51 and 52 on an overhead camshaft 53 extending across the cylinder head with its axis in a central longitudinal plane CLP of the engine.

This arrangement is made possible by forming the earns 51 and 52 so that they are conical in shape, i.e. have a basic shape which is constituted by the frustum of a cone on which is superimposed the raised portion of the cam. The generating lines of the base portion of the cam and of the raised portion lie on the surfaces of a family of cones all of which subtend the same angle at the vertex. The vertices of the cones are on the same axis but at different positions along the axis. See for example FIG. 6 where the vertices of the highest and lowest portions of the cams are shown.

Contact between the follower and the cam is along a generating line of the conical surfaces. The lifting profile of the cam is determined in the usual way and will differ slightly according to the follower mechanism used.

In this embodiment the rockers are pivotally mounted on downwardly projecting elongated supports shown generally at 54 in FIG. 7. Each support 54 comprises a rod 55 in which a longitudinally extending oil duct 56 is provided. The rods 55 are fixedly mounted in a part (not shown) which is rigid with the cylinder head.

Over the lower end of each rod 55 is fitted a generally cylindrical sleeve 57 having a part-spherical end 58 which is engaged in a correspondingly shaped socket formed in the rocker 50. The sleeve 57 is urged downwardly by a tapered helical spring 59 located between the end 58 of the sleeve 57 and a washer 62 in contact with the end of the rod 55. The spring 59 also urges the Washer 62 against the lower end of the rod 55. The washer 62 is provided with an aperture or apertures 63 through which oil can pass only when the washer 62 is forced away from the lower end of the rod 55 by the pressure of the oil in the duct 56. The oil thus admitted to the space enclosing the spring 59 pushes the rocker 50 downwards against the valve stem and the cam. When the cam starts to lift the rocker, sleeve 57 is pushed upwards compressing the oil in the space and forcing the washer 62 against its seat. Oil cannot escape from the space except for a small leakage between the sleeve 57 and the rod 55, and the upward movement is therefore quickly arrested. It amounts to approximately 0.003 in. in a typical case and the movement is taken account of in the cam design. The Washer 62 acts as a one-way valve in allowing oil to enter the space enclosing the spring 59 to take up the clearance and in sealing up the return route. This mounting for the rocker 56 provides for automatic adjustment to accommodate wear.

Each rocker 50 is provided at one end with an abutment 65 which, in this case, FIG. 7, is in engagement with the cam 52. At the other end, each rocker 50 is provided with an abutment 66 which is in engagement with the top of the stem 67 of a valve 68. The valve stem 67 is slidably located in a guide-way 69 in the cylinder head and the valve 68 is urged upwardly against its seat 72 by a spring 73 engaged between the cylinder head and a disc 74 secured on the valve stem 67. The valve 68 closes an exhaust port 75, one of two exhaust ports 75 and 76 located in symmetrical positions in the cylinder head with respect to the transverse axis VIII-VIII of FIG. 6. Two

inlet ports

77 and 78 are also provided, the two inlet ports and the two exhaust ports being located on opposite sides of a central longitudinal plane CLP through the engine.

The exhaust port 75 and the inlet port 77 are located on the opposite side of a central transverse plane (VIII-VIII of FIG. 6) through the cylinder head and combustion chamber from the inlet port 78 and the exhaust port 76.

As shown in FIG. 8, the present valve operating mechanism enables a truly part-spherical combustion chamber to be achieved and the injector 81 is located at the central point of the wall of the chamber symmetrically located between the four

ports

75, 76, 77, 73. This location for the injector 81 is especially advantageous from the point of view of obtaining etlicient combustion of the fuel.

The injector is operated by a cam 82 on the camshaft 53 through the agency of a rocker 84 which engages the operating plunger 85 of the projector at a point approximately mid-way between the ends of the rocker. A roller 86 is mounted on one end of the rocker 84- and is engaged against the cam 82. At the other end, the rocker 84 is formed with a part-spherical socket 37 which is engaged on a part-spherical support 88 formed on the end of a stud $9 screwed into a socket 90 in the cylinder head and secured against inadvertent loosening by a lock nut 21.

An alternative form of rocker 94 for operating the valves is shown in FIG. 9. In place of the abutment 65, the rocker 94 is provided with a conical roller 95 which engages one of the conical rollers, in this case 52 on the shaft 53. The roller 95 is arranged to rotate about an axis not at right-angles to the rocker 94 in order to bring the roller and the cam 52 into proper contact.

I claim:

1. An internal combustion engine having a cylinder head with at least one combustion chamber, two inlet ports opening into said chamber on one side of a central longitudinal plane through the chamber, and two exhaust ports opening into said chamber on the opposite side of said plane, spring-loaded inlet and exhaust poppet valves controlling flow of gas through said inlet and exhaust ports respectively, a single camshaft extending above said cylinder head parallel to said longitudinal plane, two cams provided on said camshaft to operate said inlet valves and said exhaust valves, means interposed between each of said cams and a corresponding inlet valve, said means consisting of a separate unitary rigid rocker, means interposed between each cam and a corresponding exhaust valve, said means consisting of a separate unitary, rigid rocker, whereby upon timed rotation of said cam shaft, each of said cams operates in sequence, respective ones of said inlet and exhaust valves.

2. An internal combustion engine having a cylinder head with at least one part-spherical combustion chamber, two radial exhaust ports opening into said chamber on one side of a central longitudinal plane through said chamber, two radial inlet ports opening into said chamber on the opposite side of said plane, spring-loaded inlet and exhaust poppet valves controlling flow of gas through said ports and disposed radially of said part-spherical combustion chamber, a single timed cam-shaft extending above said cylinder head and located in said central longitudinal plane, two conical cams provided on said camshaft, each of said cams being arranged to operate in sequence one inlet valve and one exhaust valve, said cams comprising a basic portion constituted by a frustum of a cone the axis of which is coincident with the axis of the cam shaft, and a raised portion superimposed on said basic portion, the basic portion and the raised portion having generating lines which lie on the surfaces of a family of cones all of which subtend the same angle at the vertex, and the vertices of Which lie at dilferent positions along the axis of the camshaft, a separate unitary rigid rocker being interposed between each cam and the corresponding inlet valve and a separate unitary rigid rocker being interposed between each cam and the corresponding exhaust valve, each rocker having a surface shaped for line engagement with the corresponding conical cam.

3. An internal combustion engine according to claim 1, wherein the camshaft is disposed to one side of the four valves and the rockers for the pair of valves nearer the camshaft are each supported at corresponding ends for rocking movement, the other ends of the rockers engaging the valve stems and the cams engaging these rockers at positions intermediate the ends of the rockers; and the rockers for the pair of valves further from the camshaft are each supported at corresponding positions intermediate their ends for rocking movement, corresponding ends of the rockers engaging the valve stems and the cams en gaging the other ends of these rockers.

4. An internal combustion engine according to claim 3, and including a fuel injector located centrally of the combustion chamber between the four valves, a further cam on said camshaft and located between said two cams, a further rocker for operating the injector interposed between said further cam and the injector, and a downwardly projecting support rigid with the cylinder head supporting said rocker for rocking movement, said support having a part-spherical concave surface formed on its lower end and engaged with a corresponding part-spherical convex surface formed on the further rocker.

5. An internal combustion engine according to claim 2, wherein the rockers radiate from the central vertical axis of the combustion chamber.

6. An internal combustion engine according to claim 5, and including a separate conical roller provided on each rocker for engagement with the corresponding conical cam.

7. An internal combustion engine according to claim 5, including a separate support for each rocker, each support being formed with a part-spherical end surface and each rocker being formed with a part-spherical seat engaged with said end.

8. An internal combustion engine according to claim 7, wherein each of said supports comprises a cylinder formed with a longitudinally extending duct for oil, a cylindrical sleeve having a hemispherical end portion fitted over said cylinder, a washer having at least one aperture located against the end of said cylinder with said sleeve, a spring arranged to urge said washer against said end and seal said aperture whereby oil under pressure in said duct will push said washer away from said end and pass through said aperture to urge the rocker away from said cylinder whereas light upward movement of the rocker will cause said washer to seal against said end preventing egress of oil from the hemispherical end portion and providing a fixed fulcrum for the rocker.

References Cited in the file of this patent UNITED STATES PATENTS 1,609,149 Wilkinson Nov. 30, 1926 2,054,928 Church Sept. 22, 1936 3,046,961 Dolza July 31, 1962 FOREIGN PATENTS 85,857 Austria Dec. 15, 1920 431,098 Great Britain July 1, 1935 456,688 Great Britain Nov. *13, 1936 504,467 Italy Dec. 11, 1954 674,180 Great Britain June 18, 1952 681,827 France Feb. 4, 1930