US 2237621 A
Description (OCR text may contain errors)
April 1941- K. 1.. HE RRMANN 2.237.621
INTERNAL COMBUSTION ENGINE Original Filed May l 4, 193"! 2 Sheets-sheaf, 1
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April 1941' K. L. HERRMANN 2.237.621
INTERNAL COIBUSTION ENGINE Original Filed llay14. 193"! 2 Sheets-Sheet 2 INVENTOR.
447% 4. fll'Zf/fllY/V A TTORNEYS.
Patented Apr. 8, 1941 2,237,621 INTERNAL COMBUSTION ENGINE Karl L. Herrmann, South Bend, Ind.
Original application May 14, 1937, Serial No.
Divided and this application October 29, 1938, Serial No. 237,625
This invention relates to internal combustion engines, and more particularly to combustion engines of the barrel type.
The present application is a division of my copendlng application, Serial No. 142,653, filed May 14, 1937.
The engine to which the present invention relates is of the type having its cylinders parallel to the axis of the engine, and the invention may he used with such inventions employing either a four stroke cycle, a two stroke cycle or a lliesel system. It is adaptable to engines for use in motor vehicles, aeroplanes, or in marine, railway or stationary engines.
One object of the present invention is .to provide such an engine withpower applying means that will run without vibration and which is smooth and quiet in operation, compact in size, light in weight, and more economical in the use of fuel, lubricant, and cost of maintenance perhorse power developed than the conventional type of engines now in use.
One of the main features of the present invention is the provision of a double ended piston for this type of engine, which has a sufficiently flexihle skirt so that the forces which result in sldewise pressure against the cylinder wall will be well distributed over the entire available hearing surface.
Another feature of the present invention is the provision of a bearing assembly which may be carried in the connecting portion of the double ended piston for transferring the piston thrust to the engine shaft as torque through the medium of a cam.
A further object is to provide a, double ended piston that is light in weight, is rigid with its connecting member, and is designed to eliminate localized sidewise pressure aganst the cylinder wall and is so constructed as to have substantially uniform heat dissipation.
Still another feature of the present invention is the elimination of anti-friction bearings in the double ended piston for the roller members which impart the thrust of the piston to the cam to convert it into torque on the engine shaft.
Still another feature of the present invention is the provision of a piston construction in which the connecting portion between the two ends of the piston is so designed as to afford uniform pressure distribution to the cylinder wall, adequate lubrication of the bearing surfaces between the cam following rollers and the journals or bearing supports in the piston, and also provides adequate bearing support on the cam.
Still another advantage attained by the present invention is the provision of a double ended piston so constructed as to have sufficient strength to resist the lateral stresses to which it may be subjected, and yet which has a sufficiently flemible skirt portion so as to provide the proper sealing of the piston heads in the opposed cylinders with the central portion being of sufficient strength and rigidity to maintain the piston against distortion and absorb all lateral and tangential stresses while providing for proper transmission of thrust from the piston head to the cam carried by the engine shaft through which the torque is transmitted.
Another feature of the present invention lies in the provision of a crowned contact suface on the cam engaging roller, to prevent cramping which might occur due to flexure of parts or manufacturing tolerances or clearances.
Other objects and advantages of the present invention will appear more fully from the following detailed description, which, taken in conjunction with the accompanying drawings, will disclose to those skilled in the art the particular construction and operation of the preferred form of the present. invention.
In the drawings:
Fle l is an elevatlonal view partly in section of a barrel type engine embodying the present invention;
Figure 2 is an elevational view partly in section of a piston such as may be employed for the engine shown in Figure 1;
Figure 3 is a plan view of a modified form of piston;
Figure l is an elevational view, partly in sechole, of the piston shown in Figurefl;
Figure 5 is a sectional view taken substantially on line 5-5 of Figure 4:
Figure 6 is a sectional view taken substantially on line 6-5 of Figure 4;
Figure '1 is a sectional view taken on line '|--'I of Figure 4;
Figure 815 a sectional view taken substantially on line 8-8 of Figure 4;
Figure 9 is a view showing in detail one of the cam followers in position in the piston; and
Figure 10 is an elevational view of the cam follower.
Considering now in detail the drawings. there is disclosed an lntemal combustion engine, indicated generally at 5, of the barrel type having twelve cylinders in two groups of six each.- As shown in Figure l, the engine is composed of two similar halves 6 and I bolted together as indicated at 8 substantially centrally of the engine. The drive shaft it extends axially through both halves the engine with the cylinders being equally spaced in a circle about the shaft. The drive shaft has mounted on it or formed integral with it an enlarged portion M disposed approximately midway between the ends of the shaft, this portion being positioned by the thrust bearings 82 hearing against perpendicular thrust surfaces [13 formed on the enlarged portion it. Supported on and carried by the enlarged portion ii is a T section driving cam 84 through which the driveshaft is driven from the pistons.
The shaft l6 extends the entire length of engine and is provided with journal surfaces adjacent opp site ends thereof for holding the shaft in alignment. One end of the driveshait may be provided with an ignition distributor. (not shown) and the opposite end is arranged for coupling to desired transmisnion mechanism. The cylinder block is formed two sections 09 and. 2b secured together by the bolts 8. Adjacent the ends of the cylinder block sections 69 and 29 are cylinder heads it. Both the cylinder block sections and the cylinder heads are similar, and it is not believed'that a detailed description thereof is necessary in describing the present mvention.
On the head 24 there is secured a valve cover 23 and within the cover 25 are a plurality of valves such as indicated at 26, cooperating with valve openings 21 formed in the cylinder heads for communication with the respective cylinders disposed about the driveshaft. Each of the block halves l9 and 20 is provided with six cylinder bores, such as indicated at 23, and each cylinder bore has associated therewith a piston 29 of a double ended piston such as indicatedgenerally at 30.
The double ended piston as shown more in detail in Figure 2, comprises a pair of pistons 29 and 32 connected by a connecting portion 33. The connecting portion has formed therewith a i pair of journals 34 and 35 within which there are mounted roller bearings and cam followers such as 36 and 31, the cam followers contacting with the cam l4 and transforming the energy of the pistons into torque for rotating the shaft l9.
Each of the cylinders 28 is provided with a water jacket-40 surrounding the same for cooling the cylinders, and lubricant is supplied to the cylinders between the ends of the piston 30 by means of a series of spiral baflles l2 and 43 mounted on the drive shaft l and moving lubricant from a suitable reservoir axially in opposite directions along the shaft, 9. portion of this lubricant passing through the thrust bearings l2 and thence into the interior of the cylinder between the opposed pistons 29 and 32.
The design of the double ended pistons is a special feature of my invention, and one form of such design is clearly shown in Figure 2. The piston units comprise a pair of pistons 29 and 32 connected by a connecting portion 33. The connecting or center portion may be considered as a. beam for transferring the load caused by the reciprocating compression and explosive forces to the skirts 92 of the piston heads. The beam in addition to supporting the follower rolls 33 and 31, transfers the loads well up into the skirts of the pistons. There the beam is secured to a rib '93 arranged transversely of the body portion of the piston and to a second rib 94 extending longitudinally of the piston but at right angles to the beam 33. allows the 1 expansion of the rigid rib and connects the beam through the ribs 93 and it to the semi-flexible skirt portion 92 of the piston head. he may be seen at 95, the piston head is slotted to allow for flexing thereof. The beam is preferably reenforced, as at 95, to stifien the structure through the wear pads 99' hearing on the side of the cam id. The center portion of the beam 38 may be of U section,.and the outboard bearing or wear pads 99 serve to prevent rotation of the pistons with respect to the cylinder mres. Considering now the preferred form of piston shown in Figures 3 toil, inclusive, a piston structure be is shown having the opposed piston heads '53 and 53. The skirt portions 56 and 5b respectively of the two pistons are slotted as indicated at 56 to provide for a semi-fieidble connection between the heads and the skirt, portions.
The two skirt portions 5 3 and 56 are connected by a central beam portion 6? which is arcuate in shape, as indicated in Figure 5, and.
which is provided with a central longitudinally slotted portion 58 for a purpose to be hereinafter described. As shownclearly in Figure 5,
the beam portion 571 of the piston terminates in an angled, slightly curved surface 59 at opposite sides of the piston which form wear pads hearing on the cam follower it to prevent rotation of the piston relative to the cylinder bores.
In order to reduce the wear surface, the inner part of the beam at may be undercut to clear the cam follower ii, and thus to provide opposed wear surfaces 59. These surfaces prevent rotation of the piston in the cylinder, while the arcuate portion of the beam El transmits lateral thrusts directly to the cylinder wall, allowing reducing of the rib sections in the piston.
To provide rigidity of connection between the beam portion 5! and the piston skirts 54 and 55,
the piston skirt is provided with a transverse re-enforced web portion 62 and with a longitudinally extending web portion 63 projecting 4-5 at right angles to the web 62. This provides for a rigid positive-connection between the beam portion and the opposed piston skirts with the slotted portions 56 providing the flexibility required for proper sealing of the piston heads in the cylinders. If desired to increase the strength and rigidity of the connecting beam 51, the cam follower rollers may be placed below the center of the piston, thus increasing the cross-section of the beam and also the lateral arcuate bearing surface between pads 59. 1
Below the slot 58 there is provided semicylindrical journal surfaces 54 which are in alignment with the opposite ends of the slot 53 and between which and the beam portion 51 of 50 the piston there is a cut-back portion 35 adapted to receive .the roller portions 66 of the cam followers, indicated generally at 61 in Figures 9 and 10. The cam follower 91 comprises a journal pin portion having the integrally formed cylindrical roller 81, the pin 68 having opposite trunnion or journal ends 69 and 10 adapted to be received in the ends 12 of the slot 58 and the semi-cylindrical journal portions 64 at the lower ends of the webs 62. It will be seen that with 70 such a construction the rollers 66 which engage the cam follower H are free to rotate within the cut-back portions 65 of the opposed piston skirts, while the pin 61 is journalled so that the opposed trunnion ends 69 and II thereof rotate in the semi-cylindrical journal portions 12 and 64 disthe cylinder and eliminates the necessity of roller bearings or the like such as are required in the piston construction shown in Figure 2, This also eliminates the necessity of lock rings and retainers for holding needle bearings in position, as required in the construction shown in Figure 2, and greatly facilitates the assembly of the cam followers in the pistons. The roller portions 65 may have spherical cam contact surfaces, if so desired, to prevent cramping due to fiexure or manufacturing tolerances.
It will be apparent froman inspection of Figure 1 that the lubricant directed by the spiral baille 42 along the shaft Ill and through the thrust hearing I! and into that portion of the cylinder intermediate the pistons 29 and 32 or 52 and 53 will be thrown backwardly and forwardly upon reciprocation of the double-ended piston, and will be splashed against the lateral surfaces of the journal portions 59 and III of the pin 58 as well as on the cam surfaces of the cam I4, Inasmuch as the rollers 66 are pressed onto the pins 63 and must necessarily rotate as the cam H passes therethrough, it is obvious that this film of lubricant will be passed onto the surfaces 64 and it to insure adequate lubrication thereof without the necessity of using anti-friction bearlugs to journal the pins 58. Also, it will be noted that the cut-back portions 65 in the piston skirts are slightly greater than the diameters of the rollers at, thus providing suflicient clearance to insure free movement of these rollers and also accommodating slight wear of the bearing surfaces M and it before the roller 65 will engage the surface of the cut-back portion $5.
I have found in experimentation that sufficient lubrication is provided on the journal surfaces tit and "ill to prevent any appreciable Wear thereof during a period substantially equivalent to the life of such an engine. If desired, bearing metal inserts, such as bronze or babbitt, might be provided for these surfaces or the metal might be hardened at these points if so desired. it is therefore believed apparent that I have provided a novel type of double-ended piston which is very simple in design and assembly, which requires no complicated anti-friction bearing assembly, and which can be readily inspectcd and maintained in properly lubricated condition at all times.
The inventive features of the above described piston structures as an active part of an engine assembly forms the subject-matter of my copending application for Letters Patent of the "United States for improvements in Internal combustion engine filed May 6, 1940, and serially numbered 333,519, the same being a division of the present application.
lit is to be understood that the above-described embodiments of the invention are for the pur poses of illustration only, and various changes may be made therein without departing from the scope and spirit of the invention.
I claim: l. A double-ended piston having a longitudinally extending connecting beam portion, a longitudinal slot therein intermediate the p stons,
a pair of semi-cylindrical bearings on the adjacent ends of the piston in line with the ends of the slot and forming spaced bearings with said slot ends.
2'. The combination with the piston of claim 1 of ,trunnioned cam followers journalled directly in said spaced bearings.
3. A double-ended piston having a longitudinal connecting beam portion, a longitudinal slot therein defining at opposite ends semi-cylindrical bearing surfaces, transversely spaced bosses on the adjacent ends of the pistons having semicylindrical bearing surfaces allned with said slot surfaces, cam followers having trunnion ends journalled in each set of bearing surfaces, said trunnion ends being laterally exposed to receive lubricant therein from intermediate the pistons,
4. A double ended piston structure including end piston portions and an interconnecting strut portion, said strut portion having a slot therethrough extending longitudinally of said piston, the ends of said slots being formed to provide semi-cylindrical bearing surfaces, an additional semi-cylindrical bearing surface in axially aligned and axially spaced relation with respect to each of the first mentioned semi-cylindrical bearing surfaces, a roller received between the semi-cylindrical bearing surfaces at each end of saidpiston and trunnions for each said rollers journaled in the corresponding pair of said semi-cylindrical bearing surfaces at the corresponding end of said piston.
5. A piston comprising opposed piston-like end portions axially spaced from one another and an interconnecting portion integral with both said end portions, a pair of rollers each arranged with its axis approximately diametrically disposed with respect to said piston and spaced from each other axially thereof, each of said rollers having trunnions integral therewith and projecting anially from opposite sides thereof, and said piston having bearing surfaces open to reception of said trunnions during bodily movement of said rollers and trunnions axially of said piston.
6. A double ended piston comprising, in combination, a pair of axially spaced opposed end portions forming pistons and an interconnecting strut formed integrally with said end portion, said strut having an elongated slot therein provided with semi-cylindrical end surfaces the arses of which are arranged diametrically of said piston and which surfaces form bearing surfaces, and an additional pair of semi-cylindrical bearing surfaces carried by said piston each arranged in axial alignment with one of said semi-cylindrical surfaces at the ends of said slot and being spaced therefrom diametrically of said piston.
'i". A double ended piston comprising, in combination, a pair of axially spaced opposed end portions forming pistons and an interconnecting strut formed integrally with said end portion, said strut having an elongated slot therein provided with semi-cylindrical end surfaces the axes of which are arranged diametrically of said piston and which surfaces form bearing surfaces, an additional pair of semi-cylindrical bearing surfaces carried by said piston each arranged in axial alignment with one of said semi-cylindrical surfaces at the ends of said slot and being spaced therefrom diametrically of said piston, a roller interposed between and substantially bridging the space between each pair of said bearing surfaces at the corresponding end of said piston, and trunnions integral with said rollers and received by said bearing surfaces.
, 8. In combination, a double ended piston formed to provide both laterally and longitudinally spaced semi-cylindrical bearing surfaces between the ends thereof, a cam having a rim portion interposed between the longitudinally snecesi bearing surfaces, and snti irictiozi ineni hers internoseei between ssiol cam and sexiness, esch anti-friction memher items received between at ooh oi seio ieteroliy s oes-oi snrisces and having cylindricei tnions received therehy snti maintained in substantial contact with said surfaces by the interposition oi ssioi com between said members, said members being tree to move in a direction senerslly longitudinally of soicl piston towers esch other when said cam is not interposed between them.
t. In combination, s piston structure comprising 2. pair oi sxislly aligned cylindrical enol portions and a. central portion rigidly interconnecting said end portions, said end portions being oi the same diameter and said connecting por= tion lying substantially completely within an imaginary axial extension of the peripheral surfaces 01 said end portions, halt journal hearings carried by said piston structure and arranged in pairs spaced longitudinally 01' said piston structure from one another, the rv oi each pair; being spaced from one another transversely oi soonest solo piston stsnctme, and the hearings of one peir heins stres es. with their open shies'stn emits iecins the open sioos oi oi the other pair, integral. roller one pin mounted in said holt journal hearings, and com means interposed between acid pairs of hearings and engaged between, said rollers whereby to msintein the pins thereof in wor ensssement with their corresponding halt joumel erings.
is. In combination, a, com, a, pair of rollers" adopted to roll on the respective opposite faces of sold com, trunnions fixed to each of said rollers and projecting axially from the respective opposit/e ends thereof, a piston structure, and spaced hearings for the trunnions of each oi said rollers carried by said piston structure and receiving said trunnions therein, said bearings being so formed that said trunnions are held in said bearings and said rollers are held in operative relation with respect to said cam only by the intervention of seicl cam between wici rollers.