US2150185A - Two-cycle engine - Google Patents

Description

March 14, 1939. J PHlLLlPs 2,150,185

TWO CYCLE ENGINE Original Filed June 13, 1934 I" as 15 a1 a0 n 2- 6; 70 x 7 55 B7 :l 34 E i Ii I: L

INVENTOR,

' JOHN PHILLIPS.

ATTORNEYS.

Patented Mar. 14,1939

UNITED STATES PATENT. OFFICE 'rwo-orom ENGINE John Phillips, Oakland, Calif. Original application June 13, 1934, Serial No.

Divided and this application December13, 1935, Serial No; 54,242;

' 8 Claims. (01. 12a-s5) 'My invention-relates to two-cycle engines, and more particularly to two-cycle engines of the self-firing or Diesel type.

This application is a divisionof my prior apconjunction with a positive fuel supply; to pro-' "vide a means and method for supplying a Diesel engine cylinder with a weak fuel mixture in bo's'uiliciently rich to fire on heat of compression; to provide 'a means and method for creating an explosion in said mixture; and to provide a simple and efficient two-cycle engine adapjzed to utilize low grade fuel, :5 My invention possesses numerous other objects and features of advantage, some-of which,

together with the foregoing, will be set forth in the following description of specific apparatus .embodying and utilizing my novel method. It is, therefore, to be understood that my method is applicable to, other apparatus, and that I do not limit myself, in any way, to the apparatus of the present application, as I may adopt various other apparatus embodiments, utilizing the method, within the scope of the appended claims. In myprior application above-referred to, I

have disclosed an engine operating on the twocycle principle, combined with "an air-starting system. The present application deals solely with o the power cycle of that engine and the'structure utilized to accomplish that cycle.

In the drawing, the figure is a schematic and diagrammatic representation of a single engine cylinder and appurtenances thereto, showing a 5 preferred arrangement for accomplishing tlie operation-and structure of my invention. j

-Before describing the operation of my-preferred engine, I desire to refer to the figure for a more detailed description of the structure involved, a crank case I supporting a conventional crank shaft 2 on bearings not shown, as is well known in the art.

Journaled on crank arm 3 is connecting rod 4 operating piston 5 through the medium of wrist pin 6, the piston reciprocating within a cylinder 1, the piston, of course, being provided with the usual rings 8.

I also prefer to provide the top of. the piston with an inclined surface '9 over a portion of its area, this surface being positioned to direct 5 exhaust gases through exhaust ports l0 adjacent the lowerend of the cylinder and located to be uncovered through the final 35 of the power stroke crank travel. The gases from these exhaust ports are collected 'by an'exhaust pipe ll having therein, preferably adjacent the engine,

. an exhaust "control valve l2 operated by an exhaust control arm l3 moving over a quadrant I l. The cylinder'head assembly is provided with a floating valve l5 supported by a valve spring l5 [6 operating against a valve sleeve II which in turn operates the Valve through an operatingwasher 18. The spring and sleeve are so arranged that the 'valve, when the, engine is not operated, remains cracked by a definite amount, this amount of course varying, but in a particular. engine I may prefer to allow the valve to open of aninch before spring influence occurs.

' For charging the engine with air or gaseous fuel, I prefer to utilize a positive pressure compressor comprising a compressor shell 20 where- I in there is rotated a vane web 2| having four slots 22 therein. This vane web is, as is usual in such compressors, positionedto one side of the center of the shell 20, and crossed vanes 23 are mounted'therein and freely movable in slots 22. The ends of the vanes are provided with a friction shoe 24 and a floating vane 25,

both shoe and floating vane cooperating to maintain a perfect seal at the-ends of the vanes during rotation of the compressor, thus provid ing positive pressure.

This compressor has been described in detail in my copending application, Serial No, 730,420,

filed June 13, 1934. In that prior application I have described resilient means for pressing the floating vane 25 against the inner w'allof the shell. While that method is perfectly satisfactory, I prefer in this particular instance toutilize-oil pressure to hold. the vanes against the wall, and I have therefore provided the central cavity 26 of the web 2|. with oil under pressure from line 2! leading from fuel oil tank 28. This oil passes to the backs of the vanes andpresses 5o thevanes against the wall.

Atmospheric air is taken into the-inlet' 29 of the pump through a screen 30, andthe compressed air and gas mixture is delivered to the cylinder above valve [5 through storageconduit Inasmuch as gases under pressure exist in this chamber, I prefer to take off a pressure pipe 32 therefrom and lead this to fuel oil tank 28 above the oil line, and seal the fuel oil tank,- thus providing pressure to force fuel oil into the central chamber 26 of web 2|; thence by the pump is either directly connected to or synchrocrossed vane bearings into the main compressor chamber 33 and alsoto the rear of the fly vanes 25 to force them against the shell wall. I prefer to drive this compressor at crank shaft speed, as indicated by brokengear lines 34.

On the side of the cylinder head opposite the storage conduit 3| I prefer to position a fuel in-' jection nozzle 35, supplied, as is customary in the art, from a fuel injection pump 36 receiving fuel oil through pipe 31- from fuel tank 28. While I have shown the fuel pump 36 apart from the engine, it is of course to be understood that this lined, certain relative values may be mentioned in order that the relationship of sizes and pressures may be more fully understood. For example, I have found it desirable that the free air capacity of the compressor be the same as the piston displacement of'the cylinder, and I have further found it desirable that the cubical content of the storage conduit 3| be also approximately the same as the piston displacement. Thus, there will always be a charge for the cylinder in storage chamber 3| while the next charge is making up within the compressor.

I also prefer to operate the compressor, in this specific example, to have an output pressure of fifteen pounds per square inch. With these figures and dimensions in mind, I will proceed to follow the complete cycle of operation of the device;

In the first place, and as it is customary to start engines such as-the one described above with compressed air, and as in a two-cycle engine running at full speed it is desirable to have exhaust ports of as large area as possible and uncovered before the piston reaches bottom center; it can readily be seen that these two actions are in some degree incompatible. It is therefore desirable to partially close the exhaust durin starting in order to obtain full benefit of the starting-air as it will then act on the final 35 of crank rotation. I therefore prefer, for starting purposes, to partially close valve l2 in the exhaust line, a convenient method of control being arm l3.

Airunder pressure from some suitable source is admitted to the engine through valve 31 reaching the top of the piston 8 through chamber 38. The piston will then start down, under the air influence, but at the same time the valve IE will close, due to the fact that the air pressure within the cylinder is greater than that the' storage conduit 3| As the piston 8 starts down, however, the compressor will be rotated,

raising the pressure within the storage conduit 3|, and storing therein air under pressure; this air, however, being in fact a weak fuel mixture because as pressure builds up in storage conduit 3|, fuel oil will be forced through pipe 21, past the vanes of the compressor into the compressor chamber 33, and is there mixed with the intaken air. I prefer to so adjust the leakage, eitherby construction of the [vanes themselves or by a valve, not shown, in fuel line 21, that the amount of fuel vapor in the charge stored in storage conv duit.3| is less than that which will enable the charge to be ignited by the heat of compression after it arrives in the cylinder.

As the piston reaches the downward end of its stroke and starts back up again, starting-air is of course discontinued by the proper commutating device utilized in the starter, and pressure within the cylinder is built up, due to the upward travel of the piston, thus keeping the valve l5 closed. At top dead center injection of fuel oil will take place through nozzle 35, and the cylinder will fire without utilizing any of the charge stored in storage conduit 3|. As the piston starts down, under the influence of this charge, the gases burn and pass out of the exhaust port when uncovered; and as the pressure drops, due to the exhaust of the gas in the cylinder, valve l5 will open under the influence of the pressure of the charge existing in storage conduit 3| and the charge therein sweeps into the cylinder, charging and scavenging. As the piston reverses direction and continues its upward travel, valve l5 will close as soon as the pressure inside the cylinder becomes greater than that within the storage When the charge now in the cylinder is fully compressed injection takes place, but it is only necessary now to inject just enough more fuel so that sufflcient may be added to that already present in the compressed charge to bring it up to the point where it will ignite under the heat of compression, whereupon firing occurs and the cycle is repeated. I Y

I have found, however, that certain definite pressure relationships take place during this cycle. For example, under normal operation both the cylinder and cylinder head, and at least a portion of the storage conduit 3|, are hot, due to conductionfrom thev engine; and I may desire to so design the engine that heat is readily conducted 'to the entire storage cond'uit 3| Under these conditions the stored charge is heated, and I have found that while,

the compressor-output pressure may be fifteen pounds, the pressure of the charge within the storage conduit 3| may rise at ornear the time of discharge into the cylinder; to as high as thirty pounds, the vanes of the compressor nearest the outlet then acting as valves to prevent this excess pressure from affecting the indi-,

vidual portions of the charge under compression between the vanes. Then, as the valve opens, the

charge surges'into the cylinder where it is still further heated, and the expansion of the gases. caused by the sudden accumulation of heat therein, and the exhaustion of conduit 3| by the of the valve is exceptionally snapPy-it opens quickly and closes quickly. Imay prefer, in order to prevent hammering, to utilize also a clo sure spring to ease the closing snap.

Thus, the charging of my cylinder is in reality a surge, and the surge is trapped within the ,cylinder because of the quick action of the floating valve; audit is possible, except for the desirability of the prevention of hammering of the valve with consequent tendency toward crystallization, to operate the valve without any springs whatsoever, it being controlled entirely by differential pressure. The springs are merely present to affect the degree of control and the rate of action. v

I have also found that even during the operation of the device, that the exhaust control throttle valve I2 is highly important in that it will control scavenging; in other words, partial closure of valve l2 will prevent all unburned gases from being exhausted. As the incoming charge enters the cylinder, it does not appear to mix readily with the exhaust gases but rather appears to ride on top of a layer of exhaust gas. I have 'found, therefore, that exhaust control is a convenient adjunct of throttling the engine; and I have also found that by, closing up the exhaust while running'at slow speed, the engine can be made to idle more perfectly and lug without mis flre at low speeds. It is of course entirely possible and quite practical to' tie up and interlink the exhaust valve H with either the injected fuel supply or the compressor, supply or both in order to obtain an extremely effective speed control. r

Several other features are'made available by the construction and method of operation: The,

yalve itself does not need a perfect'seat; the valve can be made nearly as large as the cylinder diameter, and therefore requires only a short opening; a long piston'stroke withits accompanying advantages may be used; no timing of.

the fact that in multicylinder engines pistons in adjacent cylinders may be placed at different crank angles, one storage conduit iii and one compressor may be'utilized to supply adjwent l cylinders; the supply of fuelgas is synchronized with the needs and use of the engine in direct proportion to the speed as the compressor rotates synchronously with the crank shaft.

In the discussion of the .mechanical parts i above, I have mentioned that'I prefer to leave Ian auxiliary chamber 38 extending laterally from the end of the injector nozzle 35. This I find is valuable in keeping the injector nozzle clean, as during the operation of the engine the mixture within this chamber will be insumciently charged to'ignite, but the gases in the chamber will be afiected by the variouspressure changes in the cylinder. Thus, there is a continual breathing of gas to and from this chamber past the outlet of the injector nozzle, thus tending to keep the nozzleclean, to completely remove all fuel, and to obviate. the possibility of fouling by carbon or other foreign materials.

In addition, the breathing action of the auxiliary chamber removes'fuel oil dribbling-:from

the injector after injection and propels it'into; the combustion chamber, thus helping to redeem any imperfection in the initial combustionf J I claim:

5 1. The method ofoperating 'an internal COIIif v bustion engine which comprises externally compressing a charge of weak fuel-air mixture, stor- I ing said charge and simultaneously heating said charge, releasing said heated charge into a heated engine cylinder to still further increase its pressure, compressing said charge, and adding sufficient liquid fuel to said charge to cause ignition by heat of compression.

2. The method of operating an internal combustion engine which comprises externally compressing a charge of weak fuel-air mixture having a volume at intake temperature having a desired ratio to piston displacement, storing said charge and simultaneously heating said charge, releasing said heated charge into a heated engine cylinder to still further increase its pressure, utilizing said increased pressure to trap said charge in said cylinder, compressing said charge and adding sufficient liquid fuel to said charge to cause ignition by heat of compression.

3. The method of operating an internal combustion engine which comprises externally compressing a charge of weak fuel-air mixture having a volume atintake temperature having a desired ratio to piston displacement, storing said charge and simultaneouslyheating said charge by .heat generated by engine operation to increase its pressure, releasing said heated charge into a heated engine cylinder to still further increase its pressure utilizing said increased pressure to trap said charge in said cylinder, compressing said charge and adding suflicient liquid fuel to said charge to cause ignition by heat of compression.

4. The method of operating an internal combustion engine which comprises externally compressing a charge of, weak fuel-air mixture storing said charge and simultaneously heating said charge by heat generated by engine operation to increase its pressure without ignition, releasing said heated charge into an engine cylinder in the form of a surge, compressing said chargein said engine cylinder and adding additional fuel thereto to cause ignition.

5. The method of operating an internal corn-- bustion engine which comprises externallycompressing a charge of weak fuel-air mixture, storing said charge and simultaneously heating said charge by heat generated by engine operation to increase its pressure, releasing saidv heated charge into an engine cylinder while exhaust ports are open, and controllingthe effective aperture of said exhaust ports during operation.

6. The method of'operating an internal com- I bustion engine which comprises externally com-,

pressing a charge of weak fuel-air mixture, having a volume at intake temperature substantially equal to piston displacement, storing said charge and-simultaneously heating said charge by heat generated by engine operation to increase its pressure releasing said heated charge into a heated engine cylinder to still further increase its pressure, utilizing said increased pressure to trap' said charge in said cylindericompressing said charge, adding sufficient liquid fuel to said charge to cause ignition by heat. of compression, externally c'ompressing and preheating another charge during the utilization period of the first charge and controlling the effective aperture of said exhaust ports during operation.

Y 7. An internal combustion engine comprising a cylinder and a piston, and an unrestrained inlet valve for said cylinder operable to open and close solely in accordance with the pressure balance on opposite sides thereof, means for storing a. charge of gas underpressure on the inlet side of said valve during the period when engine compression closes said valve, means for releasing exhaust gas pressure in the cylinder after combustion has taken place thereby causing the charge to surge into said cylinder, said charge being trapped by automatic closure of said valve, and means for adding sufiicient fuel to said gas to cause firing by heat of compression. v

8. In combination with an engine cylinder and 'mixture to the proportions causing combustion.

J OI-m PHILIPS.

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