US1825691A - Internal combustion engine - Google Patents

Description

ct. 6, 1931. E. 5 HALL INTERNAL COMBUSTION ENGINE Filed Sept. 8. 1927 2 Sheets-Sheet 1 Inventor 7 54; F W

Get. 6, 1931. s, HALL 1,825,691

INTERNAL COMBUSTION ENGINE Filed Sept. 8, 1927 2 Sheets-Sheet 2 g F" N g4 v v Fig, 6

= Inventor Patented Oct. 6; 1931 UNITED STATES PATENT OFFICE EDWIN SYDNEY HALL, OF NEW HAVEN, CONNECTICUT INTERNAL COMBUSTION ENGINE Application filed September 8, 1927. Serial No. 218,223.

' m for any purpose, the construction disclosed herein being peculiarly advantageous when applied'to those engines used for such variable load service as that required of an automobile or a locomotive power plant. 5 I More specifically, the chief objects ofmy invention are to provide in an internal combustion engine, the following novel features: Means for governing the power output, not only by throttling, but by controlling the length of piston stroke in a manner making it possible to change readily to any len th of stroke between and including zero an a suitable maximum; means whereby the compression ratio may be kept constant irrespective of the length of piston stroke, or

Varied as a suitable function of stroke length, whichever may be most desirable;-

and means whereby the compression ratio may be easily adjusted to any value between 33 desirablelimits, while the engine is running.

To one who is familiar with the theory' and practice of internal combustion engines,

numerous advantages of an engine incorporating my invention will be apparent from the foregoing objects, as noted in the following description, accompanying drawings,

and appended claims. In the drawings:

4b Figure 1 is a longitudinal section.

a study of the practical accomplishment of to in the following discussion concerning the manner in which the compression ratio is controlled.

Figure 6 is a diagrammatic view of the swash plate and conoidal cam, in perspec-" tive, the position being that corresponding to zero piston stroke.

Figure 7 is a longitudinal section of apistonand yoke assembly of somewhat different detail from that shown in Figure 1. i

In the following description, referring to the particular embodiment of my invention shown'in the drawings, the following notation is used: I

Reference numerals 1 to 9, inclusive, refer to reciprocating parts;

Reference numerals 10 to 19, inclusive, refer to stationary parts; and a Reference numerals 20 to 33, inclusive refer to rotating parts, some of which also have some axial movement.

Referring to the drawings, cylinders 11 in cylinder block 12 are disposed about the main shaft 20 with their axe equidistant and parallel thereto. Each vpiston 1 is adapted to reciprocate in its respective cylinder 11 and is operably connected to the rim of swash plate 23 by means of connect-. ing rod 3 (which may be integral with piston 1), yoke 4 and 'adjoined parts, as follows: v

Yoke 4 is constrained to move only in linear motion parallel to the axis of cylinder 1'1, being shdably mounted on two guide studs 10 which may also help to hold the cylinder block 12 and crankcase 13 together. The two branches of yoke 4 are disposed one on either side of the rim of swash plate 23, and each branch bears one of a pair of thrust shoes 5 having plane faces I separated from the swashplate rim only by. a film of oil. J

The backs of thrust shoes 5 are formed as portions of the surface of the same sphere, and are mounted in spherical sockets 6 and 7, so that thrust shoes 5 may be self aligning with respect to the swash plate rim; In Figure ,3 several thrust shoes 5 are showri in plan View. swash plate 23- moves, with respect to thrust shoes 5, in the direction in- 106.

dicated by the arrow. This is the well known Kingsbury thrust bearing construction which provides a wedge of oil on which the shoe ma ride. Each thrust shoe 5 may have a ten ency to turn out of line; this tendency is checked by the interlocking character of the tongue and slotted extensions on thrust shoes 5, as shown.

Referring again to Figure 1, socket 6 is fitted into a cylindrical seat of fixed depth in yoke 4; socket 7 is set in a cylindrical hole in the opposite branch of yoke 4 and abuts directly against the flanged end of connecting rod 3, the surfaces of the connecting rod flange being also spherical and con centric with the spherical surfaces of thrust shoes 5. I

The outer spherical surface of the flange of connecting rod 3 is constrained by the corresponding surface of nut 8, (split to permit assembling), which screws into yoke and is locked in place by binding bolt 9.

This construction serves two useful purposes, namely: wear in the entire connecting rod assembly may readily be taken up by' loosening bolt 9, screwing nut 8 into yoke 4 a sufficient distance, and then relocking with bolt 9; the flexibility of the manner of connectmg yoke 4 to connecting rod 3 helps to revent the piston from cramping in the cylinder, which might otherwise occur if the guide studs 10 should become worn or sli htly out of alignment.

igure 7 shows a simpler construction of the yoke assembly lacking this latter feature. Here the connecting rod 3 is screwed directly into yoke 4, and rigidly locked by Bolt 9. This would be a cheaper construcion.

Swash-plate 23 is pivoted on a pair of pins, com rising essentially a transverse or cross sha t 22, whose axis is perpendicular to the axis of the main shaft 20. The pins comprising cross shaft 22 are carried in bosses on sleeve 21 which is internally spllned to shaft 20 in a manner to permit axial but not rotative movement between sleeve 21 and shaft 20. Sleeve 21 can rotate in the journal bearing 15 and projects thru it into hydraulic cylinder 14. Sleeve 21 carries a hydraulic piston 24 ada ted to be operated in hydraulic cylinder 14 y differential oil pressure furnished thru ports 16 and 17 by suitable pumping equipment which may be located in the space 18.

The hydraulic piston 24 and cylinder 14 may thus be the means by which the axial position of the cross shaft 22 may be varied. Mechanical or other means instead of hydraulic, could be provided without de parting from the scope of my invention.

When axial movement of the cross shaft 22 occurs, the arm 33, which is a part of swash plate 23, rides along a contour of cam 30. In practice, the arm 33 is provided with a suitable bearing shoe, omitted here for the sake of clearness. The interaction of arm 33 and cam contour 30 gives to swash plate 23 a predetermined slant from the normal position, for every axial position of cross shaft 22 along main shaft 20.

Cam 30 is mounted in a bearing 19 adapted to take both radial and thrust loads, and in a manner providing some axial adjustment of cam 30 with respect to crankcase 13.

Main shaft 20 passes thru cam 30 and is connected thereto by a multiple thread in such a way that axial movement of the shaft 20, produced by an outside force operating as on the shift collar 25 may rotate cam 30 with respect to the shaft 20 an amount not necessarily more than one revolution, for the purpose of bringing various other cam contours into contiguity with arm 33 thus altering the angle of swash plate 23. Note that except while making thisadjustment, shaft 20, sleeve 21, cross shaft 22, plate 23, and cam 30, all rotate together at the same angular velocity.

Shaft 20 at its rearward end is also splined into the hollow transmission shaft 31, which is centered preferably not by shaft 20 but by the collar 32 which is, in effect, a part of cam 30.

Figure 5 shows a kinematic sketch of my invention, wherein the mechanism is shown with an even number of cylinders. Ordinarily in a four stroke cycle engine of this general type, an odd number of cylinders is used in order to get a satisfactory firing order. An even number is preferable, however, for the sake of dynamic balance, and a suitable firing order may be had by using twice an odd number of cylinders. Also for the purpose of explaining the kinematics of my invention, an even number of cylinders is preferable as shown in Figure 5, where 8=1ength of stroke, proportional to the piston displacement in one cylinder;

v=1ength of clearance volume, proportional to the clearance volume;

h=radius of the "cylinder circle" thru which pass all the axes of cylinders 11;

R=compresslon ratio;

a=a radius dependent on R, (a is the ordinate of the (ppipzti l which is fixed for-any constant value c and k are'constant lengths which locate the end of arm 33 with respect to swash plate 23.

The compression ratio, R 7

according to customary usage.

s a a b By similar triangles, T :Fh

Therefore, R ill d a h R 1 from which a hR 1.

a is thus a function of the compression ratio R.

For a constant value of R, a will be constant and the curve of the cam contour is given by the parametric equawhere is the anglie of tilt of the swash plate from its position normal to shaft 20.

Figure 6 shows diagrammatically the swash plate 23 in position normal to shaft 20 corresponding to zero piston stroke. This view shows also the conoidal shape of cam 30, which it assumes when it is shaped to tions,

yield a constant compression ratio for any given setting relative to shaft 20, and at the same time, a continuous adjustment of compression ratio between limits, by movement relative to shaft 20. In this case, each contour of cam 30, (a contour being defined as the' intersection of a plane thru the axis shaft 20, or in other words maintain a fixed angle of swash plate 23 relative to shaft 20, in which case, axial movement of the swash plate would change only the compression ratio,-leavin the piston stro'ke constant.

j Again, wit the variable stroke, one com p'ressiom ratio may be all that is desired. Then cam 30 would have but one contour, and it would, be unnecessary to provide means for rotatingor otherwise moving cam 30 on shaft 20. Or means might be easily provided for moving this one contour relative to shaft 20 to adjust the compression ratio, in case some ad ustment were desirable. Further several contours may be combined on a cam of shape similar to a polygonal pyramid, the various contours being brought into use one at a time b means similar to thdse described'herein. e ideal case indicated in Figure 6 results when the number of surfaces on such a polygonal cam is allowed to approach infinity.

The cam contours shown in Figures 5 and 6 are actually plotted for the ideal compression ratios noted, in a mechanism proportioned to the scale of the drawings. Simi-- larly, the upper contour in Figure 1 would yield a compression ratio of 3, and the lower, a compression ratio of 5. A cam of this sort, cooperating with axial movement of the swash plate, is obviously a very flexible melans of fitting this type of engine with an almost limitless assortment. of compression ratios.

V For ideal efiiciency, in operation, the pow; er output of an engine embodying my invention would be controlled by varying the piston stroke by changin the axial position of cross shaft 22, either by the hydraulic means'indicated, or by other suitable means, The throttle on the carburetor would normally be carried wide open, thus avoiding all throttling losses, but means should be provided to automatically close the throttle more or less while decreasing the length of piston stroke. I vIt may be preferable to use manual control on the throttle in the usual way, adjusting the piston displacement necessary to produce the required power, by a lever in lieu of the usual gear shift lever. If enough maximum piston displacement is provided, no transmission would be needed except for reversing, since the equivalent. of a continuously variable transmission is inherent in p the engine mechanism itself.

The ability to adjust the compression ratio, independently of piston stroke length,

while the engine is running, not'only is significant in regard to economy and the possibility it offers of using a supercharger for maximum torque while at the same time maintaining high efficiency at reduced load, but it is a valuable feature for ice also.

' While I have shown specific structures for the purpose of illustratlngmy invention, it is understood that I do not limit myself to them alone, but include also structures which are substantially. equivalent to those described herein.

I claim:

airplane serva} ios 1. In an internal combustion engine, a

rotatable shaft, cylinders disposed about said shaft and having their axes parallel thereto, a swash plate rotatable with said shaft and mounted thereon, pistons reciprocatory in said cylinders and operably connected to aid swash plate, and means for varying the length of stroke of said pistons while maintaining their compression ratio in said cylinders substantially constant. I

2. In an internal combustion engine, a rotatable shaft, cylinders disposed about said shaft and having their axes parallel thereto, a swash plate rotatable with said shaft and mounted thereon, pistons reciprocatory in said cylinders and operably connected to said swash plate, and means for varying the length of stroke of said pistons while maintaining their compression ratio in said cylinders substantially constant, said means comprising essentially: means for moving said swash plate axially with respect to said cylinders, projecting means on said swash plate,and a cam en'ga gedthereby and having a contour approximating that mathematically necessary for constant compression.

3. In an internal combustion engine, a rotatable shaft, cylinders disposed about said shaft'and having their axes arallel thereto, a swash plate mounted on said shaft, pistons reciprocatory in said cylinders and operably connected to said swash plate, a cam associated with said shaft, means for moving said swash plate axially with respect to said cylinders, means 011 said swash plate engaging said cam and cooperating with said axial movement to control the tilt of said swash plate, and means for adjusting said cam relative to said shaft.

4. In mechanism of the sort described, the combination with a swash plate having a variable angular tilt relative to its axis of rotation, of a reciprocatory member comprising a pair of sockets formed as portions of the same spherical surface, a pair of thrust shoes seated therein and engaging opposite sides of said swash plate, a piston, and connecting means between said pistonand said sockets.

5. In mechanism of the sort described, the combination with a swash plate, of a reciprocatory member operably connected thereto,

guide members'on which said reciprocatory member is slidable, a pair of sockets formed as portions of the same spherical surface and borne b said reciprocatory member one on either si e of said swash plate, and lubricated thrust shoes seated in said sockets and having substantially plane faces engaging opposite sides of said swash plate. V

6. In mechanism of thelsort described, a rotating swash plate, lubricated thrust shoes arranged in pairs on either side thereof and maintained in ali nment by tongue and slot\ extensions with tfie corresponding shoes of adjacent pairs.

7 In mechanism of the sort described, the combination with a swash'plate having a variable angular tilt relative to its axis of rotation, of a reciprocating member comprising a pair of soc ets formed as portions of the-same-spherical surface, a pair of thrust shoes seated therein and engaging opposite sides of said swash plate, a iston having a flanged piston rod, said flange having spherical surfaces concentric with said sockets, and adjustable means for connecting said flange to one of said sockets.

,8. The combination with a swash plate, of a reciprocating member associated therewith, including a'pair ofthrust shoes havingplane faces arranged in lubricated apposition on opposite sides of said swash plate and having back surfaces which are portions of substantially the same spherical surface, spherically shaped seats for said thrust shoes, a piston rod having a flange with spherical surfaces, an adjusting member arranged to adjustably connect said flange with one of said seats and adjustably maintain one of said seat members in relation to the other.

9. In mechanism of the sort described, the

combination with a swash plate of a reciprocating member comprising a pair of sockets formed as portions of t e same spherical surface, a and engagin op osite sides of said swash plate in lubricate apposition, a piston, connecting means between said piston and said sockets, and adjusting means wherewith to adjust the working clearances of said combination.

10. In, an internal combustion engine, a shaft, cylinders having their axes parallel tosaid shaft, pistons in said c linders a swash plate on said shaft an rotatable therewith, operative connections between said pistons and said swash plate, means for varying the compression ratio in said cylinders and means forvarying the stroke of the pistons while maintaining the compression ratio in the cylinders constant.

EDWIN SYDNEY HALL.

air of thrust shoes seated therein

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