US1370503A - Fakken - Google Patents

Description

W. W. MACFARREN AND T. W. GRAY.

GAS ENGINE.

APPLICAHON FILED MAR. 3, l9l9.

2 SHEETS-SHEET l.

FIE-2.1.

INVENTORS W. W. MACFARREN AND W. GRAY.

GAS ENGINE. APPLICATION FILED MAR. 3, I919- Patbntd Mar. 1, 1921.

2 SHEETS-SHEET 2.

INVENTORS UNITED STATES PATENT OFFICE.

WALTER W. MACFARREN, OF PITTSBURGH, AND'THOMAS W. GRAY, 0F HEIDLEBERG, PENNSYLVANIA, ASSIGNORS TO SAID WALTER W. MACFARREN, TRUSTEE.

GAS-ENGINE.

Specification of Letters Patent.

7 Application filed March 3, 1919. Serial No. 280,261.

To all whom it may concern Be it known that we, WVAL'rnR WV. MAO- FARREN and THOMAS W. GRAY, citizens of the United States, residing, respectively, at Pittsburgh and Heidleberg, in the county of Allegheny, State ottPennsylvania, have invented certain new and useful Improvements in Gas-Engines, of which the following is a specification.

Our invention relates to internal combusion engines and more especially to those working on the four stroke cycle. Our improved engine may be constructed with any desired number of cylinders but is herein shown with four cylinders.

The objects oi. our invention are:

let. To produce a 4 cycle engine in which each cylinder will fire at each revolution instead of once in every. two revolutions as usual, whereby the power output is approximately doubled.

2nd. To increase the piston speed without increasing the speed of the shaft, whereby the heat loss to thewater jacket is lessened and the efiiciency increased.

3rd. To reduce the weight of the reciproeating parts by eliminating the connecting rods. 1

4th. To eliminate the crank shaft and substitute therefor a straight shaft which may be conveniently mounted in antifriction bearings.

5th. To substitute vfor the cranks, cams which may be designed to obtain more efiicient control of the motion of the piston.

6th. To provide a direct contactingdevice between each piston and its cam by which power is transmitted from piston to shaft and vice versa.

7th. To provide a cushioning device to control the outer reversal of the piston.

8th. To v provide a differential piston stroke whereby the lengths of the power,

exhaust, inlet and compression strokes can be separately best adapted for their respective functions.

9th. To provide automatic means for maintaining the fluid pressure pistoncushion at maximum effectiveness.

10th. And to provide various detailed improvements in the design and construction of such engines whereby they may be made more satisfactory and efficient.

Referring to the dra'wing'sf Figure 1 is a sectional side elevation of our improved engmc. Fig. 2 is a transverse cross section of the same, and Fig. 3 is a view similar to Fig. 2, showing a modified form of engine.

The shaft 1 is mounted in a split crank case having an upper. part 2 and a lower part 3, and is provided with a cam 41 for each cylinder. The cylinders 5 have each an upper bore 6 and a lower bore? in which there works atwo diameter piston 8 with upper piston rings 9 engagingthe upper bore 6 and lower piston rings 10 engaging the lower bore 7.

A cylinder head 11 is provided with inlet valves 12 and exhaust valves 13 both of which may be of any desired construction and operated in any desired manner. An inlet manifold 14 supplies gas to the cylinders and the exhaust passes out through an exhaust manifold 15. The clearance vol ume 16 above the upper piston 8 is the space in which the explosion takes place. Power is transmitted from the piston 8 to the cam 4 through a roller 17 mounted on a pin 18 secured to the lower end of the piston 8. Asshown in Fig. 2 the engine is on the dead center and may be supposed to be just starting a power stroke in eitherv direction of rotation, it being understood of course that the cam 41 is carried around by the momentum of the connected moving parts.

.As soon as the high point 19 passes the center line of the engine the piston 8 moves downward under the force ofv the exploding gases and the roller 17 exerts pressure on the cam 41. toturn it until the low point20 is in contact with the roller 17, when the piston hasreached the bottom of its stroke. As the cam continues to revolve the part between 20 and 21 bearing against the roller 17 will force it upward,,thus giving the piston an up or exhaust stroke. 7

During the quarter turn from 21 to 22 the piston may travel downward again on its inlet stroke, and during the quarter turn from 22 to 19 the piston 8 will be forced upward by the cam 4 on its compression stroke.

In a vertical engine at slow speed the above described operation would take place by the force of gravity acting on thepiston 8, but at high speed it requires an additional limit of its travel on the exhaust stroke. It

Patented Mar. 1, 1921.

is also of advantage to have a positive check on the upper motion of the piston during the compression stroke as in case of a valve sticking there would no compression ob tained.

To obtain this necessary force we have provided a cushioning device acting on the upper side of the enlarged lower portion of the piston 8, and comprising a manifold 23 which forms a small reservoir for compressed gas or air. This manifold as shown in Fig. 2 is supplied with pressure from the exhaust manifold through a pipe 2i which leads through a reducing valve 25, to

a second ipe 26 connected with the manifold 23. he reducing valve can be setto maintain a constant pressure in the manitold 23 below that of the exhaust from the manifold 15. A port 27 leads into the upper end of the enlarged bore 7.

As there is at all times a constant pressure in the manifold 23 the upward mo vcment of the piston or pistons is resisted thereby. and it is a matter of designing skill to so an range the area of the lower annular piston. and the pressure carried in manifold 23 in such proportion to the speed of the ei'igine and the weight of the piston. to keep the roller 17 at all times in contact with the cam 4.

\Vhen the engine is built with only one cylinder the manifold is simply an air spring. the air passing in opposite directions through the port 27 as the piston moves up or down.

n the preferred construction a a nuilticylinder engine having four cylinders as shown, two of the pistons move down as the other two move up, and thus the air is displaced by the upward moving pistons to supply the downward moving pistons. In either case there will be a certain amount of leakage past the rings 10. and to take care of this some pressure producing device is necessary. .As the PI'ESSJIG of the exhaust is considerable this may in some cases be used as just described. and by the use of a reducing valve this pressure is made constant in the reservoir as soon as there is any drop in. pressure the valve admits more gas.

Tn Fig. i?- we have illustrated a similar arrangement in which the pressure is taken from the interior of the power cylinder itself instead of from the exhaust. By this means a much higher pressure can be obtained.

in passing it will be noted that by reason of the sealing efi'ect of the rings 10 at the lower part of the piston 9. copious splash lubrication may be used in the crank case. as no considerable quantity of oil can leak upward past these rings due to the existence of a constant pressure above them.

In Fig. 2 we have shown the cams 4 as symmetrical and of substantially elliptical form. It will be understood. however, that since each quadrant of the cam represents a stroke of the piston itcan be individually shaped to obtain the most advantageous acpelled by its movement n'actically all the products of combustion.

The following stroke will be an inlet stroke, during which the roller will travel on the cam 28 from point 3 to point 32. This stroke will be of equal length to the exhaust stroke and will draw in a charge which will practically fill the piston displacement plus the clearance volume.

As the cam continues to revolve the roller 30 will travel from point 32 to point 34 and the piston 33 will move upward on a coin- 'iression stroke. However, this stroke will be shorter than the exhaust and inlet strokes because the distance from the center of the shaft 2-9 to the point 341 of the cam is less than the corresponding distance to the point ill. On the following or power stroke the piston will travel downward and the roller will roll from point 34 to point 25. As shown the upper or longer half of the cam controls the inlet and exhaust strokes. and the lower or shorter half of the cam controls the compression and power strokes.

The advantages of this differential movement of the piston are well known, as the cylinder is completely scavenged of burned gases at each cycle, and draws in a full and unadulterated charge of fresh gas. The length of stroke required to give the proper clearance volume and compression, and the proper length of power stroke may be varied at will by changing the dimensions of the cam.

The cams 28 are also shown as being of substantial elliptical contour. but as before stated. each quarter of the cam may be made of any shape desired. It will be noted that the symmetrical cam shown at 4 is in perfect balance. whereas an unsymmetrical cam as shown at 28 is out of balance; this may be corrected however by forming an opening at 40 of such a size and at such a distance from the center as to make a running balance.

In the preferred construction of a four cvlin der engine the outer two cams are placed at right angles to the inner two cams as shown in Figs. 1 and 2; thus the movement of the outer pistons is exactly the same and is opposed to the movement of the inner pistons. As the pistonsmay be made of exactly equal weights, this produces a very efliclent running balance. If in addition the cams are symmetrical or balanced with each other, the whole engine will be well balanced. Further, since the cams are of considerable size and weight, the necessity for a fly wheel may be in many casesdispensed with. i i I In order to prevent the rotation of.the

pistons and keep the roller pins18 in proper possible with crank shafts at the ends only,

whereas with our construction a bearing may be put between each pair of cams if desired.

The. valve mechanism, drive therefor, ignition system, and carburetor have not been described in detail, as they form no part of this invention. 4 The outstanding difference between this engine and other four cycle engines is the fact that a complete cycle of four piston strokes is obtained for each revolution of the shaft. By this means the power at the same shaft speed is approximately doubled, and if the scavenging eflect illustrated in Fig. 3 is also used the power will be more than doubled. In addition to this, the efiiciency will be increased by reducing the heat loss to the water jacketor other cooling means, this loss being to a great extent dependent upon the speed of the piston, it being well known that high speed engines lose a less proportion to the jacket than low speed ones.

It will be obvious to those skilled in the art that our improved engine may be built as a. V type motor of eight cylinders by using two four cylinder blocks as illustrated and setting them at with each other to opcrate on a single shaft having four cams, each cam receiving power from two cylinders. Twelve or sixteen cylinder motors could be similarly built on a four cam shaft.

We claim as our invention:

1. In an internal combustion engine, a power cylinder, a power piston working therein, a shaft, a cam on said shaft, a contacting device carried by said piston and engaging said cam, and a pneumatic cushioning device comprising an enlarged cylinder below the power cylinder and concentric therewith, an annular flange formed at the lower end of the piston and working in therein, a shaft, a cam on said shaft, a contacting device carried by said piston and en gaging said cam,and a pneumatic cushioning device for cushioning the piston on its in stroke, including a reservoir, means for charging said reservoir with pressure generated in the power cylinder, and means for maintaining a substantially constant pressure in said reservoir. v

4. In an internal combustion engine, a

power cylinder, a power piston working therein, a shaft, a cam on said shaft, acontacting device carried by said piston and engagingsaid cam, and a pneumaticcushioning device including a reservoir, for cushioning the piston on its upstroke.

5. In an internal combustion engine, four parallel cylinders, a shaft, a power piston in each cylinder, an oval cam on the shaft for each cylinder, the two outer of said cams having their long diameters at a right angle to the long diameters of the two inner cams, and a contacting device for each piston en gaging its cam, in combination with an enlarged cushioning cylinder below each power cylinder, a flange at the bottom of each power piston working in said enlarged cylinder, an air reservoir, and a port connecting each of said cushioning cylinders with said reservoir.

6. In an internal combustion engine, a cylinder, a piston, a shaft, a cam thereon, a contacting device on said piston engaging said cam, a pneumatic spring cooperating with said contacting device to cushion the piston on its upstroke, a source of pressure, and a connection between the same and said spring device.

7. In an internal combustion engine having four cylinders, each of said cylinders having a smaller and a larger bore, stepped pistons working in said cylinders, a shaft, a cam on said shaft for each of said cylinders, and a contacting device on each of said pistons toengage one of said cams, a fluid pressure manifold, and a port leading from the larger bore of each of said cylinders to the said manifold, the whole arranged so that two of said pistons move oppositely to the other two whereby the workdone by the fluid pressure against two of said pistons is balanced by the work done against the fluid pressure by the other two pistons.

8. In an internal combustion engine, a

cylinder, {rs-piston, a shaft, a cam on said. shaft, a contacting device on said piston engaging said camwvhereby the movement of the piston is determined by the contour of the cam, a fluid pressure device for maintaining the engagement of the contacting device with the cam, and a pipe connecting the combustion space in the cylinder with the fluid pressure device to supply the same with fluid pressure.

' 9. In an internal combustion engine having a plurality of cylinders, a piston for each cylinder, a shaft, a cam on said shaft for each of said pistons, a contacting device on each piston engaging its co-acting cam, whereby the movement of each piston is determined by the contour of its cam, a fluid pressure device for each piston to maintain the engagement of its contacting device with its cam, a manifold connecting the pneumatic devices for all the pistons, and a pipe connecting the combustion space in one of the cylinders with said manifold to supply pressure thereto.

10. In an internal combustion engine, a cylinder, a piston, a shaft, a cam on said s aft, a contacting device on said piston engaging said cam to drive the same, and a pneumatic cushioning device in line with said cylinder and cooperating with said piston to maintain the engagement of said cam with the contacting device on the piston.

11. In an internal combustion engine, a cylinder, a piston, a shaft, a cam on said shaft, a contacting device on said piston engaging said cam to drive the same, and a pneumatic cushioning device concentric with said cylinder and cooperating to maintain the engagement of said contacting device and said cam.

12. In an internal combustion engine, a plurality of cylinders, a shaft, a cam on said shaft for each of said cylinders, a piston for each cylinder, a roller on each piston engag ing one of said cams, an individual pneumatic cushioning device for each of said pistons to maintain the engagement of said roller and said cam, and means for supplying pressure to said cushioning devices from a common source of supply.

In testimony whereof we hereunto afiix our signatures in the presence of a witness. f

W. W. MACFARREN. THOMAS W. GRAY.

Witness.

A. M. Goonwm.

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