US2243820A

US2243820A - Internal combustion engine

Info

Publication number: US2243820A
Application number: US358240A
Authority: US
Inventors: Karl L Herrmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-09-25
Filing date: 1940-09-25
Publication date: 1941-05-27
Anticipated expiration: 1958-05-27

Description

y 1941. K. L. HERRMANN 2,243,820

- INTERNAL COMBUSTION ENGINE Filed Sept. 25, 1940 2 Sheets-Sheet l r INVENTOR- j-Z 1, Herr/yarn;

' May 27, 1941. K. L. HERRMANN 2,243,820

INTERNAL COMBUSTION ENGINE Filed Sept. 25, 1940 2 Sheets-Sheet 2 Patented May 27, 1941 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Karl L. Herrmann, South Bend, Ind. Application September 25,1940, Serial No. 358,240

7 Claims.

This invention relates 'to internal combustion engines and particularly to those of the barrel type, the principal object being the provision of a new and novel form of connection between the pistons and the cam which will reduce the amount of wear heretofore occurring at this point,

The invention relates to what is commonly known as a barrel type of engine, that is an engine in which the cylinders are arranged with their axes parallel to the shaft and equally angularly arranged about the shaft and with such axes lying in acylindrical surface concentric with the axis of the shaft. The cylinders are arranged in two groups, one group at each end of the engine and each cylinder of each group is in opposed relation to a corresponding cylinder of the other group and with a double ended piston associated with each opposed pair of cylinders, the shaft being provided with an axial cam received by the central portion of the pistons and rollers being interposed between the opposite faces of the cam and the pistons to transmit the thrust between the pistons and the cam.

Objects of the invention include, in an engine of the type described, a roller construction which will take care of any mis-alignment between the rollers and the cam faces and yet will distribute the wear between the rollers and the cam over a desired width of face of the cam; the provision, in an engine of the type described, of a roller construction which will have substantially point contact with the cam but in which the line of contact between some rollers and the cam will be in a circle having a diiferent radius from the line of contact of other rollers with the cam; theproof the crown on certain of the rollers occurring 40 than the high points of the crown on other rollers;

at a different distance radially ,of the engine shaft and the provision of an engine of. the type described in which the various rollers interposed between the cam and the pistons are crowned with the high points of the crowns of the various rollers arranged at various positions axially of the rollers whereby the points of contact of certain of the rollers with the cam occurs at a different radial distance from the center of the engine shaft than the point of contact of other of the rollers with the cam.

The above being among the objects of the present invention, the same consists in certain novel features of construction and combinations of Parts to be hereinafter described with reference to the accompanying drawings, and then claimed, having the above and other objects in view.

I In the accompanying drawings which illustrate a suitable embodiment of the present invention and in which like numerals refer to like parts Fig. 3 is a transverse sectional view of the piston taken on the line 3'-3 of Fig. 2;

Fig. 4 is a fragmentary transverse sectional view taken on the line 4-4 of Fig. 1 and illustrating the arrangement of the cylinders; and,

Figs. 5, 6 and 7 are enlarged fragmentary, sectional views taken on the lines 5-5, 6-6 and 1-4, respectively, of Fig. 4 and illustrating the construction and arrangement of the rollers interposed between the pistons and the cam.

The present invention relates to a barrel type engine. As is well understood in the art these engines comprise a rotating shaft about which is grouped a plurality of equally angularly spaced cylinders arranged with their axes lying in the surface of a cylinder concentric with the shaft. The cylinders in the present case, and as is usual, are arranged in two groups, one at each end of the engine with their open ends opposed to each other and each cylinder of one group in alignment with one cylinder of the opposite group.

' Each opposed pair of cylinders receives therein a double ended piston, and a cam fixed to the rotating shaft is received within or by the central portion of each piston. Usually, and as in the case of the present invention, the pistons support rollers which engage the opposite faces of the cam so as to reduce the friction between the piston and the cam when the thrust of the pistons under explosions in the cylinders is exerted upon the cam to induce a rotational effect thereon.

While the present invention is applicable to any satisfactory type of barrel type engine, it is particularly applicable to the engine construction shown, described and claimed in my co-pending application for Letters Patent of the United States for improvements in Internal combustion engine, filed May 14, 1937' and serially numbered 142,653. Also, while the rollers may be supported in the pistons in any suitable manner in accordance with the present invention, the preferred method of supporting them is that shown and described in my co-pending applications for Letters Patent of the United States for improvements in Internal combustion engine, filed October 29, 1938, and serially numbered 237,625 and filed May 6, 1940, and serially numbered 333,519, respectively Early experiments with this type of engine illustrated the difficulty of so accurately machining the various parts that all of the rollers between the pistons and the cams, when provided with cylindrical peripheral surfaces, will bear against the cam with true line contact, the surfaces of the complished the results sought to be obtained, that is eliminating the disadvantages formerly occurring because of a cooked condition between the rollers and the cam. Further experiments have indicated, however, that with this crowned construction above described, because all of the rollers are made identical, the wear between the rollers and the cam is concentrated upon a substantially narrow circular path upon the face of the cam and, due to the high pressures existing between the rollers and the cams at full engine operation, premature wearing and breaking down of the cam surface sometimes results, and it is the principal object of the present invention to eliminate this further disadvantage.

This disadvantage is overcome in accordance with the present invention by employing crowned rollers, but crowning certain of the rollers differently from certain other of the rollers. Briefly stated, this is accomplished by arranging the high point of the crown on one or more of the rollers in a diiferent plane axially of the roller than the high point of the crown of one or more of the.

other rollers. Theoretically at least all of .the rollers on one side of the cam may be arranged with the high point of its crown at a different axial position on the roller than the high point of all other rollers on the same side of the cam, but ordinarily it will not be necessary to go to such extremes inasmuch as it has been found that if the rollers on one side of the cam are provided in two or three groups each havingits crown high point at a different axial position than the high point of the crown of the rollers of the other group or groups, the life of the cam is increased sufficiently for all practical purposes. As will be appreciated by employing such construction the wear on the cam is cutdown, as compared to a similar construction having all'rollers crowned identically and identically arranged, by the number of groups of dissimilarly crowned rollers em-- ployed inasmuch as the wear, due to this new construction, is distributed over the face of the cam in as many wear circles as there are groups of cams.

cations above referred to and reference to which may be made for greater detail of the construction of such engine if desired, As far as the present invention is concerned it is sufficient to understand that the engine is provided with a central shaft l0 suitably mounted for rotation within a pair of cylinder blocks indicated generally at l2 which are arranged with their ends in axially abutting relationship and securedtogether by means of bolts I4. The axially outer ends of the cylinder blocks l2 are each closed by a suitable cylinder head indicated generally at 16 which supports. suitable inlet and/or exhaust valves such as l8 controlling the admission of combustible mixture to and the exhaust of burnt gases from the various cylinders of the corresponding block. Suitable valve actuating mechanism is driven from the shaft ID at each end of the engine and each is normally enclosed by a housing indicated generally at 20 carried by the corresponding cylinder head Hi. In the particular construction shown by way of illustration each cylinder block I2 is internally formed to provide six cylinders 22 arranged with their axes in the surface of a cylinder concentric with the axis of the shaft I0 and equally angularly spaced with respect to each other about the axis of such shaft. The cylinders 22 of one cylinder block l2 are arranged in axial alignment with the corresponding cylinders of the other cylinder block and in each opposed pair of the cylinders 22' a double ended piston indicated generally at 24 is reciprocably received.

A: piston 24 employed in the particular engine shown and which is preferable, but not necessary to the practices of the present invention, is shown in greater detail in Figs. 2 and 3 from which it will be noted that it includes opposite end portions 26 integrally connected together by means of a ,central strut 28 substantially wholly disposed on one side of a diametrical plane passing through the axis of, the piston. This strut 2-8 is centrally slotted as at 30, the central axis of the slot lying in a plane including the axis of the piston 24 and the opposite ends of the slot 3|] comprising semi-cylindrical surfaces arranged with their axes perpendicular to the axis of the piston. A corresponding semi-cylindrical surface 32 is formed on the opposite side of the piston in alignment with the semi-cylindrical surfaces first described and the corresponding piston portions 25 are centrally cut-away as at 34 between each aligned pair of semi-cylindrical surfaces. These semi-cylindrical surfaces form bearing surfaces for the trunnions of the rollers which themselves are received in corresponding pockets 34 and project outwardly toward one another therefrom.

A cam member 38 is fixed to the shaft lil on line with the joint between the cylinder blocks I2. The cam member 38 is formed with a rim 40 which is circular in axial, view but the axial faces 42 of which curve axially of the shaft In in a simple harmonic curve to provide a cam surface on each side thereof having two diametrically opposed .axial high points thereon. The width ofthe rim MI is such as to be closely received between the rollers received in the opposed pockets 3! of. each piston 24, thus constraining each piston to reciprocate in its corresponding cylindersas the rim l0 passes between its corresponding roller-sand such rollers acting upon the corresponding faces 42 of the rim 40, under the force of an explosion'in one of the corresponding cylinders, to impart a rotatlonal effect to the cam member 38 and consequently the shaft l0. .By employing two axial high points on the cam member 38, it will be appreciated that each piston completes four strokes for each revolution of the power shaft Hi.

In the broader aspects of the present invention it makes no difference whether the rollers are formed integrally with their trunnions or not, whether the rollers turn with their trunnions, or whether the trunnions are fixed in the pistons and the rollers turn on the trunnions. Where the semi-cylindrical bearing surfaces for the trunnions are employed as described and shown, the rollers are preferably formed integrally with the trunnions and one trunnion 50 thus projects from each side of each roller when the latter is received in the corresponding pocket 34, the one trunnion being received by V the corresponding semi-cylindrical bearing surface 32 and the opposite trunnion being received by the corresponding semi-cylindrical bearing surface formed at the corresponding end of the slot 30.

As previously stated, in my second and third co-pending applications above referred to,- the rollers were formed with crowned peripheries which, technically at least, therefore, contacted the corresponding cam surfaces 42 in point engagement, and inasmuch as all of the rollers were identical and the high point 'of the crown occurred at substantially the identical axial position on each roller, all of the rollers on each side of the cam member contacted the corresponding face of the cam along a single line on such face. While from a practical standpoint despite the fact that theoretically point contact occurs between each of the roller and the cam, there is suflicient resiliency in the metal of the rollers and the cam to effect a small surface contact between these parts, but nevertheless'the width of this area of contact between the rollers and the cam surfaces is so limited that when all of the rollers on one side of the cam contact the cam over such limited width it has been found that the surface of the cam, while standing up sufficiently long to render the construction entirely practical, does not stand up for a length of time commensurate with the length of time which other parts of the engine stand up in service.

In order to obviate this premature breaking down of the cam surfaces it is the object of the present invention to provide a roller construction which will distribute wear between the rollers and the cam surfaces over an increased width of the cam surfaces. In accomplishing this result the same general type of crowned rollers as extent as it has been found that the wear on the cam will be reduced 'sumciently for all practical purposes if two or three different lines of contact between the rollers and their corresponding cam faces is provided instead of the single line provided by the former construction, and the labor and time initially involved in. setting up machinery to produce such a great variety of contact lines is largely eliminated and the requirements for carrying a relatively large number of different parts in stock for service is materially reduced.

In the broader aspects of the invention the desired result may be obtained in two difierent ways. The first of these is to .make all of the rollers identical but to mount them in their pistons at sufliciently different distances from the axis of the power shaft to obtain the desired result. vSuch a construction, however, requires the pockets 34 in the pistons 24, in'the particular piston construction shown by way of illustration, to be varied in position transversely of the piston to conform to the different positions of the rollers desired, and a corresponding change in any 0 other piston design. This would require as many different types of pistons in an engine as there are different lines of contact between the rollers and each cam surface, and, therefore, is not desirable to use for that reason. The second and most desirable way to achieve the desired result is to make all of the pistons identical: and vary the position of the high point of the crown on the rollers to provide the desired number of lines of contact between the rollersand the cam faces.-

In other words. the pistons are all identical, and the rollers are all identical except for the position axially of the rollers at which the high point of the crowned surface occurs. This last described construction being preferred, it is illustrated in the drawings.

In the particular construction shown in the drawings the rollers are so crowned as to arrange for three different lines ofcontact between the rollers and each face of the cam. This, in view previously employed is employed, the difference being that the rollers are so constructed and/or ent axial position on the cam than the high point of the crown on other rollers. As will be appreciated, by such a construction one roller will contact the cam surface along a line that is at a greater or lesser distance from the axis of the power shaft of the engine than the line of contact between the cam and another roller. It is, of course, possible to so arrangethe construction that each roller on each side of the cam contacts the corresponding face of the cam along a line on the face of the cam different from the line of contact of allother rollers with the face of the cam, and in such case each roller would have a separate line ofcontact between it and the face of the cam. From a practical standpoint, however, it is not necessary to go to this I arranged that the high point'of the crown of at least certain of the rollers is located at a differ- I 0 struction.

of the fact that the particular engine shown employs six cylinders in each of the cylinder blocks, provides a construction whereby not more than two rollers engage a cam surface along the same line of contact instead of six as in the older con- It is also noted that while it will usually be desirable that both rollers in the same piston be similarly crowned and similarly arranged so that their respective lines of contact with their corresponding cam surfaces will be at the same distance from the axis of the power shaft of the engine, this is not necessary as even though the rollers in the same piston are crowned at different axial positions no detrimental effect will result.

In the construction shown in the drawings it is assumed that the rollers on every third piston in each block will be crowned the same and similarly arranged, and the construction and arrangement illustrated in Figs. 5, 6 and 7 is illustrative of a preferred arrangement. In other words, in the construction illustrated in Fig. 5 the rollers are illustrated at 60a; in Fig. 6 at b,

and in Fig. '7 at 60c. It will be understood that it is assumed in the particular construction shown. that all of these rollers are integral with their corresponding trunnions 60, and that the rollers are of an axial thickness substantially equal to the thickness of the various pockets 34 in the piston 24 so as to be maintained against substantial axial movement transversely with respect to its corresponding piston. It will also be understood that all of the rollers are of circular conformation in any section taken perpendicularly to the axis thereof, and each are of such maximum diameter that when in normal position with respect to each of the corresponding pistons the rim 40 of the cam member 38 will be received between them with a desired minimum amount of play.

The rollers 60a are each so formed that the high point of its crowned surface, that isthe point in the axial length of the roller which is of greatest diameter, is midway between the opposite ends thereof. In other words the high point of the crown is centrally disposed between the opposite ends of the rollers andfwhere the rollers are aligned with the cam surfaces 42 as illustrated, the rollers 68 will contact this corresponding surface 42 centrally of the width there-' of. On the other hand, the high points of the crowns on the rollers 60b are dlsposed nearest that side of the rollers 60b which is closest to the axis of the shaft I0 and, therefore, contact the corresponding cam surfaces 42 along a circular line concentric -to but radially inwardly ofiset from the line of contact of the rollers 60a with the cam surfaces 42. The rollers 600 in turn are arranged with the high points of their crowns adjacent that end of the rollers more remote from the axis of the power shaft l0, and consequently these rollers contact the corresponding cam surfaces .42 along a line concentric with the line of contact between the rollers 60a and the cam surfaces 42 but radially outwardly ofiset therefromh Thus the rollers 60a, 60b and 600 contact the corresponding cam surfaces 42 along circular lines of different radiion the cam faces 42, thus providing three lines of contact between the rollers and their corresponding cam surface on the same side of the cam member and serving to reduce the wear on the cam surface because of contact of the rollers therewith by one-third as compared to the older construction. By this relatively simple modification of the older construction the useful life of the cam member may be increased to an extent to render its life commensurate with the life of other operating parts of the engine.

It might be noted that in'the construction illustrated in Figs. 5, 6 and '7 and as above described it is only necessary, when the rollers and pistons are suitably designed, to actually produce only two different types of rollers as in such case the rollers 60b and 600 may be identical with each other and simply reversed end-for-end from one another when assembled in their respective pistons.

It will, of course, be appreciated that for the purpose of illustration the amount of crowning of the rollers as shown in the drawings has been greatly exaggerated, and that in actual practice the amount of crowning will ordinarily be no greater than required to realize the purposes of the invention as described.

Formal changes may be made in the specific embodiment of the invention described without departing from the spirit or substance of the broad invention, the scope of which is commensurate with the appended claims.

What I claim is:

1'. In an engine of the class wherein a group of cylinders are arranged about each end of a cably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers having crowned peripheries, at least one of said rollers contacting its corresponding cam surface at a different radial distance from the axis of said power shaft than the point of contact of another of said rollers with the same cam face.

2. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement. with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers having crowned peripheries, and at least one of said rollers being formed with the high point of the crown thereof at a different axial location thereon with respect to the axis of said power shaft from the high point of the crown of another of said rollers on the same axial side of said cam.

3. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by. each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers being of circular section in a plane perpendicular to the axis thereof and the diameters of said sections varying from one end of each said roller to the other end thereof with the section of maximum diameter intermediate the ends of the rollers, the section of maximum diameter of at least one roller being located at a distance from one end of said roller different fromvthe distance which the section of maximum diameter of another roller on the same side of said cam is located with respect to the corre-' sponding end of such other roller.

4. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft andeach cylinder of each group is aligned with and opposed to a cylinder of the other group,'a double ended piston is recip rocably received by each opposed pair of cylinders, and an axial cam is fixed to the powershaft and is provided with curved cam faces on' axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers having crowned peripheries, and the high point of the crown of one of said rollers being located at a greater distance from the axis of said power shaft than the high point of another of said rollers on the same side of said earn.

5. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is recipro cably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers hav ing crowned peripheries, and the rollers on each side of said cam being arranged in groups, the rollers of one of said groups engaging the corresponding of said cam faces along a line disposed at a greater distance from the axis of said power shaft than the line of contact between the rollers of another group and the same cam face.

6. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding, cam face of said cam, said rollers having crowned peripheries, said rollers being so constructed and arranged in their respective pistons that the line of contact between a roller for one piston and its corresponding cam face is disposed at a different radial distance, measured from the axis of said power shaft, than the lines of contact between the corresponding rollers carried by the said pistons next adjacent to said one piston and on angularly opposite sides thereof, with said cam face.

7r In'an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially oparranged in groups on each side of said cam member, a roller of one group being so constructed and arranged to contact the corresponding cam face at a radial distance from the axis of said power shaft different from the distance between the point of contact between the corre-- sponding roller carried by the'next adjacent plstons angularly on either side of said piston, with said cam face.

KARL L.