US1954113A - Internal combustion engine - Google Patents

Description

April 10, 1934. L. M. WOOLSON 1,954,113

I INTERNAL COMBUSTION ENGINE I Filed Oct. 10, 1929 2 Sheets-Sheet. 1

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INTERNAL COMBUSTION ENGINE Filed Oct. 10, 1929 2 Sheets-Sheet. 2

Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE 1,954,113 INTERNAL CODIBUSTION ENGINE Application October .10, 1929, Serial No. 398,619

16 Claims.

This invention relates to internal combustion engines, and more particularly to engines of the type in which explosions occur through the heat of compression.

With the type of engine referredto, it is obvious and well-known that starting is difficult due to the temperature of the cylinders being much lower than that required to cause combustion of the fuel introduced therein. When such engines are used for aeronautical purposes, I have found that when a cylinder stops firing during flight, which occurs usually when gliding or when the fuel supply is reduced, then the air which is of a lower temperature than combustion temperature tends to chill such missing cylinder, and renewal of firing is difficult to accomplish. Both of these conditions are undesirable and become more pronounced as lower temperatures are encountered.

It is an object of this invention to utilize compression ratio changing mechanism for increasing the heat development in the cylinders so that there will be a higher compression ratio when the engine is under lighter loads and vice versa, such mechanism also serving to increase the volume of the airsupply conversely with elevation, within cruising limits when used as the power plant for airplanes.

' Another object of my invention is to provide an internal combustion engine of the type set forth in which the temperature within the cylinders is automatically regulated inversely to the quantity of fuel in the combustion charge.

A further object of my invention is to provide an internal combustion engine, of the compression ignition type in which fuel and air are introduced separately into the cylinders, having automatically actuated mechanism for maintaining a constant horse power in different elevations with a given quantity of injected fuel.

Still another object of my invention is to provide an aeronautical engine in which the compression ratio is automatically regulated by and inversely relative to the engine load, whereby the lowest ratio is present under the greatest load" and 'vice versa. 1 I

Another object of the invention is to provide an .internal combustion engine with a compression ratio changing device which will also absorb the explosion shocks ordinarily transmitted to and absorbed by the crank shaft.

Other objects of the invention will appear from the following description taken in connection with the drawings forming a part of this specification, in which:

Fig. 1 is a rear elevation of an engine, partially broken away andpartially in section, with which the invention is incorporated,

Fig. 2 is a section view of the same taken on line 2-2 of Fig. 1,

Fig. 3 is a perspective view of the eccentric and counterweight element of the compression ratio changing mechanism,

Fig. 4 is a fragmentary sectional view taken on line 4-4 of Fig. 2.

Referring to the drawings by characters of ref- .6! erence, 10 represents a barrel type of crank case for an internal combustion engine of the Diesel type, in which liquid fuel and air are introduced separately into the working chambers and ignited by the heat developed by compression in the cyl- 7C inders. Extending radially from the casing are a plurality of cylinders 11 which are secured rigidly to the casing, pistons 12 being arranged to ,reciprocate in the cylinders. .The casing is divided" into three aligned compartments 13, 14, and 15, 76 the forward compartment 13 providing a lubricating oil reservoir, the end compartment 15 providing a housing for mechanism actuating the cylinder valves and the fuel'pumps, while the central compartment,'which aligns with the cyl- 80 inders, is the crank case proper.

The central axial portion of the crank case is formed as a hub for the reception of a single throw counterbalanced crank shaft 16, suitable bearings 173 18, and 19, being arranged intermediate the hub and the crank shaft. Secured to the forward end of the crank shaft is an aeroplane propeller 20 which the engine illustrated is designed to rotate. The design of the propeller obviously is an important factor in determining the engine load, as the engine develops only the load which the propeller will absorb, and such loads vary with propeller design.

The cylinder heads are provided with a single port 21 through which air is drawn during the suction stroke, the engine illustrated being of the four-cycle type, and such ports are also utilized as the exhaust outlet, although separate valves for the inlet and exhaust can be employed equally as well A valve member 22 is arranged 1m to control the inner end of each port, such valves being unseated by rocker arms 23 actuated by rods 24 and normally closed by the springs 25. Suitable mechanism, intermittently operated from the shaft, is employed to unseat the valve rods in the desired sequence. A high pressure liquid fuel injection device is associated with each cylinder to spray fuel into the cylinders, each of such devices consisting of a pump portion 26 and a nozzle or atomizing portion 27, the pumps be- 11 ing intermittently actuated through rods 28 operated from the crank shaft by suitable mechanism in desired sequence, and adjustable to vary the quantity of fuel injected as desired. Air is first injected into the cylinders, and then during compression thereof, liquid fuel issprayed into the cylinders, combustion taking place through the heat of compression caused-by the operation of the pistons. The operation, and the details of the structure so far described, are fully set forth in my Patent No. 1,896,387, issued February '7, 1933. It will be understood that a high speed engine capable of running above 1500 R. P. M. is required for aeronautical purposes, and the engine illustrated will operate above such speed and is designed to sustain flight when running at approximately 1400 R. P. M.

.The pistons are connected to the crank pin 29 through a master rod 30 and connecting rods 31 pivotally mounted in circular relation around the hub of the master rodby pins 32, such connections being conventional with radial engines. Ordinarily, however, the master rod is mounted concentrically upon the crank pin and the com pression ratio is defined and unchangeable.

In order to assist starting or bringing in of cylinders which have ceased firing during flight or otherwise, I propose to associate mechanism with the master rod and crank shaft so that the compression ratio is automatically varied inversely with and by the load on the engine.

As a means for accomplishing such results, I provide an eccentric bushing or sleeve 33 intermediate the hub of the master rod and the crank pin, such sleeve being rotatable relative to both the master rod and crank pin and being arranged intermediate the crank cheeks. The crank end center of the master rod structure is shown at A, and as this point is eccentric to the axis B of the crank pin, an increase in load will actuate the master rod structure to move the eccentric sleeve 33 in a clockwise direction looking from the cockpit, asshown by the arrow on the crank pin in Fig. 1, thereby shifting the position of the master rod relative to the crank pin to decrease the compression ratio. Looking from the front of the aeroplane, the crank shaft rotates anti-clockwise while the eccentric rotates anti-olockwise to decrease the compression ratio and clockwise to increase the compression ratio; In the structure shown the compression ratio range is preferably 20 to 1 at the maximum and 10 to l at the minimum, the piston strokes being shorter with the lower ratio and longer with the higher ratio.

In order to prevent actuation of the eccentric until predetermined loads are present in the engine, and to resist the movement of the eccentric from a position providing a maximum high compression ratio, I provide mechanism which I have preferably associated with the crank shaft. To this end, the eccentric sleeve is provided with a flange 34 at one end having teeth 35 formed in the periphery thereof. The end of the crank shaft adjacent the sleeve flange is bored axially to accommodate mechanism for resisting movement of the sleeve to decrease the compression ratio, and for returning the sleeve to normal position as the load decreases. A rod 36 extends through the bore of the shaft and isforrned with a gear 37 exteriorly of the crank cheek and meshes with the teeth of the eccentric flange. A member 38, functioning as a retainer and bearing member for the rod, is screwed into the end of the bore in the crank cheek, and a carriage 39 having an interior worm groove is mounted to reciprocate in the shaft bore, the carriage having lugs 40 engaging in grooves 41 in the crank shaft to prevent rotation thereof. The rod is formed with a worm 42 engaging the carrier worm groove so that upon rotation of the rod, through its meshing relation with the eccentric sleeve flange, the carriage will be reciprocated. In order to oppose sleeve rotation in a direction reducing the compression ratio, a coil spring 43 is arranged in the crank shaft bore and encircling the rod.

A shaft extension 44 is screwed into the forward end of the crank shaft bore and carries internally a pair of bearing members 45 and 46 intermediate which packing 47 is arranged. The spring 43 extends between and bears against the carriage 39 and the bearing 45 and adjustment of the extension 44 determines the tension of the spring which can thus beregulated as desired. The rod extends through the shaft extension and a thrust bearing 52 and a retainer nut 53 and lock nut 54 are screwed upon the threaded end of the rod extending through the thrust bearing. The member 38 and the thrust bearing flx the rod longitudinally, but allow rotation thereof; a bearing member 55 retains the propeller on the shaft and is retained by a sleeve 56 which screws upon.

the shaft extension, such sleeve also serving as a starter clutch. When the shaft extension is adjusted so that it does not engage the end of the crank shaft, then retaining means therefor will, be required.

Adjustment of the sleeve 44 will regulate the spring compression, and in this instance a pressure of 2000 pounds is exerted by the spring in opposition to movement of the carriage. With aeronautical engines it is desirable that the spring be regulated so that the eccentric sleeve will not rotate until the R. P. M. is such that the engine will sustain flight, which in this instance is approximately 1400 R. P. M. Thus, it will be seen that the spring serves to automatically return the eccentric to high compression relation as the load falls off, and to act as a resistance which will permit movement of the eccentric to lower the compression ratio only as the load increases sufliciently to overcome the same. When the spring is fully compressed, the compression ratio is at its lowest point, and in this manner the lowest ratio of the range can be determined as desired for different engines and conditions. It will be seen, therefore, that the compression ratio will be automatically varied with the load, and that when idling, or with fuel injection charges of smaller quantities, the load will not overcome the spring thus maintaining a high compression ratio which causes the cylinders to become warmer than when the compression ratio is low, whereby such increased heat is transmitted to the fuel mixture therein which will promote combustion heat and consequently assist starting and bringing in of cold cylinders. The spring tension is overcome proportionately to the load the propeller imposes on the engine, thus allowing movement of the carriage and rotation of the rod and eccentric sleeve so that lower compression results thereby reducing pressure and temperature in the cylinders.

The spring 43 furthermore, serves as a vibration damper, as explosive shocks which ordinarily are transmitted to the crank shaft will be absorbed thereby.

As previously described, the master rod center A is eccentrically arranged relative to the center of the crank pin B during the entire range of the compression ratio device movement, and when the master rod center moves relative to the crank iii pin center, the centrifugal force of rotation will result in an unbalanced engine. In order to overcome such unbalanced condition, a weight 50 is mounted opposite the rod eccentric point of mounting to bring about equilibrium of the master rod relative to the crank pin so that there is no movement of the center of gravity of the compression ratio changing device in its range of movement relative to the crank shaft. The weight 50 is secured to the flanged end 3'4 of the eccentric sleeve by rivets 51, or other suitable securing means. The weight will act as a counterbalance, and I have found such a device to be an important adjunct to the practical use of compression ratio changing devices.

The term load appearing in the specification and' claims includes engine explosion forces which are qualified by torque, for example in an aeroplane engine the torque is determined by the propeller characteristics. 7

As the air density decreases with increased elevation, it is necessary with present engines to increase the fuel quantity in the charges. with increasing elevation in order to maintain a constant horse power. This invention automatically maintains the air compressed in the cylinder at a constant density, within cruising elevational limits, and consequently a constant horse power can be maintained with a uniform fuel charge regardless of elevation. With the horse power and fuel quantity of the charges thus maintained constant, the speed of the aeroplane propelled by an engine with this invention associated therewith will increase while elevating because the propeller load decreases.

The compression ratio structure above described is compactly associated with the engine, and has proven very useful for the purposes herein pointed out.

Various changes can be made in the structure herein illustrated and described without departing from the spirit of the invention and the scope of what is claimed.

What I claim is:

1. In an internal combustion engine, the combination with the engine cylinder, piston, crank shaft and crank, of an eccentric rotatably mounted on the crank, a connecting rod coupled to said piston and engagingsaid eccentric, the forces of explosion being transmitted to the cocentric through the rod in a direction tending to rotate the same, a member concentric with the crank shaft and connected to rotate with said eccentric, and means carried by the crank shaft including a coil spring resisting the rotation of the rotatable member relative to the crank shaft. I

2. In an explosive engine, a crank shaft, an eccentric rotatable on the crank shaft pin, a piston connecting rod engaging said eccentric, said eccentric being rotated relative to the crank shaft by explosion forces transmitted through the rod, and resilient means carried by the crank shaft and associated with said eccentric absorbing vibration caused by explosions.

3. The method of operating an internal combustion engine comprising introducing air charges into the cylinder, introducing fuel charges into the cylinder, and regulating the compression ratio through explosion forces inversely to the engine load.

4. In a Diesel engine having a crank shaft, a plurality of cylinders, a movable wall associated with each cylinder to define therewith the bustion engine combustion space, and means connecting the walls with the crank shaft and responsive to engine explosion forces to regulate the compression ratio inversely with the variance of the crank shaft load.

.5. The method of operating an internal comcomprising introducing air charges into the engine cylinders, introducing fuel charges into the air charges in the cylinders, and automatically varying the compression ratio by the explosion forces inversely to the engine load above a predetermined amount.

6. The method of operating an internal combustion engine comprising introducing air charges into the engine cylinders, introducing fuel charges into the air charges in the cylinders, and automatically varying the compression ratio by the engine explosion forces inversely with the engine load. 7

7. In an explosive engine, a crank shaft, a cylinder, a piston reciprocable in the cylinder, mechanism connecting the piston with the crank shaft including compression ratio changing mechanism, and means associated with the compression ratio changing mechanism for absorbing explosion forces;

8. In an internal combustion engine, a cylinder into which air and fuel are introduced, a movable wall, said cylinder and said wall forming a combustion chamber, movable means connected with the wall adapted to regulate the capacity of the combustion chamber during the introduction of air, and adjustable means associated with the regulating means to control its movement, said control means being automatically adjustable in response to explosion forces.

9. In an internal combustion engine, a cylinder into which air and fuel are introduced, a movable wall, said cylinder and said wall forming a combustion chamber,-movable means connected with the wall adapted to regulate the capacity of the combustion chamber during the introduction of air, adjustable means associated with the regulating means to control the movement thereof, said control means being automatically adjustable in response to the forces of explosions, and means associated with the adjustable means opposing the adjusting effect of ciated with the eccentric sleeve in a relation resisting the rotating effect of the explosion forces. 35

11. In a Diesel engine, a crank shaft, a plurality' of cylinders in which air charges are compressed and commingled with fuel charges, a movable wall associated with each cylinder and defining therewith the combustion chamber, and means connecting the walls with the crank shaft, said means being responsive to engine explosion forces to automatically regulate the compression ratio inversely to the torque of the crank shaft.

. 12. In an engine, a plurality of cylinders in which fuel mixtures are compressed, a crank pin, pistons in the cylinders, a hub carried by the crank pin, connecting rods between the hub and the pistons, and shiftable eccentric bearing means intermediate the hub and the crank pin, said bearing means being shifted on the crank pin in response to explosion forces to automatically change the hub relation angularly of the crank pin.

13. In an engine, a plurality of cylinders in which fuel mixtures are compressed,- a crank pin, pistons in the cylinders, a hub carried by the crank pin, connecting rods between the hub and the pistons, shiftable eccentric bearing means intermediate the hub and the crank pin, said hearing means being shifted on the crank pin in response to explosion forces to automatically change the hub relation angularly of the crank pin, and resilient means resisting movement of the bearin means from the explosion forces.

14. In an internal combustion engine, a cylinder into which air is introduced and compressed, a movable wall associated with the cylinder and forming therewith a combustion space, movable means connected with the wall and adapted to vary the capacity of the combustion chamber during the introduction of air, and adjustable mechanism including spring means associated with the movable means, said mechanism being adjustable in response to explosion forces.

15. In an aeronautical motor, cylinders having valve means through which air is introduced, a movable wall associated with each cylinder, the cylinders and their associated movable walls defining combustion spaces into which air and fuel charges are introduced, and means for automatically changing the relation of the walls relative to the cylinders below a predetermined elevation and without increasing the quantity of the fuel charges to vary the capacity of the combustion spaces in accordance with elevation during the admission of air.-

16. In an aeronautical motor, cylinders having valve means through which air is introduced, a movable wall associated with each cylinder, the cylinders and the walls defining combustion spaces into which air charges and fuel charges are'introduced, and means responsive, below a predetermined elevation and without increasing.

the quantity of the fuel charges, to applied torque for automatically changing the relation of the walls relative to the cylinders to vary the air capacity of the combustion spaces inversely with air density during the intake of air.

LIONEL M. WOOLSON.

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