US2119878A - Two-cycle engine - Google Patents

Description

June 7, 1938. EXEL 2,119,878

- Two-05mg@ ENGINE Filed `Ju1y 29, 193e 2 sheets-sheet 1 Y M1 v ATTORNEY'.

June 7, 1938. G. ExEL. 2,119,878

TWO-CYCLE ENGINE Filed July 29, 1936 2 Sl'zeets-Sheel 2 *In 1N VENTOR) Geo r9@ Exel 'ATTORNEY Patented June 7, 1938 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to two-cycle internalcombustion engines and it consists in certain improvements in such engines especially when of the type of that of my Patent No. V2,063,666 in which there is a xed piston and a cylindrical moving or power piston containing ,the iixed piston and contained in the cylinder of the engine, the construction being such in that case that each charge admitted to the primary compression chamber or space between the xed and power pistons is by-passed, upon compression therein and at the end of each stroke of the power piston toward the fixed piston, to the space between the power piston and cylinder head forming the explosion or secondary compression chamber.

It is found in practice that, due to the high vacuum developed in said primarycompression chamber when the power piston moves from the fixed piston, lubricating oil, nding its way from the crank-case up between the cylinder and power piston, is drawn into said chamber through the port in the power piston affording communication between such chamber and the intake of the cylinder, such oil not only tending to foul the engine but being Wasted at the exhaust in the absence of any expedient for recovering it. Accordingly, I provide herein for the prompt and certain removal of the oil from said chamber and for its recovery.

The invention also contemplates providing the power piston with means below the Iixed piston for preventing a surfeit of oil working up between them and accumulating above the xed piston.

The invention also contemplates a novel construction of that end of the power piston to which the piston-rod is connected designed to give said end the necessary strength and stability notwithstanding the power-piston skirt is intentionally formed as thin as possible.

The invention further contemplates so constructing the upper end of the power piston as to insure adequate lubrication thereof.

In the drawings,

Fig. 1 is a View, partly in elevation and partly in vertical section in the plane of the wrist-pin, of the improved engine;

Fig. 2 is a section on line 2-2, Fig. 1;

Fig. 3 is a fragmentary View of the cylinder, power piston and sleeve partly in section and partly in elevation;

Fig. 4 shows fragments of the cylinder, power piston and collar 30 in section in the said plane and a fragment of the wrist-pin in elevation;

Figs. 5 to 9 are diagrams showing the positions of the power piston and its ports respectively in V(not shown); the cylinder 2 bolted to said plate and closed at its upper end and having intake 3, exhaust port or opening 4 and passage 5 forrn-V ing a Icy-pass; the xed piston 6 supported on the plate by standards l; the body 8 of the cylindrical and reciprocatory power piston closed at its upper end and having its skirt depending between the xed piston and cylinder, its upper end being equipped with piston-rings 8a; the housing 9 whose reservoir c communicates with the interior of the cylinder through passage 5, such housing, with the cylinder, plate I, fixed 20 piston and standards, forming the fixed structure of the engine; and the wrist-pin IIJ and pistonrod II oscillatory on the wrist-pin and in a suitable opening in the plate and adapted to be connected to some rotary driven element, as a crank-shaft (not shown) journaled inthe crankcase, are or may be all substantially the same, except as will appear, as in my said patent. and b are, respectively the primary and secondary compression chambers.

Besides said body 8 the power piston includes a sleeve I2 which, intervening ybetween the skirt of such body and the cylinder and being elastic and having a normal inside diameter greater than the outside diameter of the skirt, tends to expand and so hugs the cylinder internally. Said body, just below the piston rings, has a circumferential groove 8b and from its head end to a shoulder 8c near its other end, which is expanded, it is of less diameter than the inside diameter of A4:0 the cylinder so as to accommodate. said sleeve, which abuts said shoulder on the one hand and on the other has an inturned portion I2a, here a circumferential flange,-engaged in the groove. To prevent the sleeve from turning relatively to ,45 the piston body and so bring its split coincident with the ports said body has a lug or lugs I3 engaged in holes in the sleeve.

The power piston has what I term a secondary inhalationl port I4 which, when said piston ad- 50 joins the closed end of the cylinder, communi- I cates with the cylinder intake 3; an exhalation port I5. which at this time communicates with the by-pass passage 5; and a primary inhalation port I6 which communicates with said passage 5 55 when the piston head approximates the fixed piston. The arrangement of the fixed piston and port 3 is such that when the power piston is completing its movement to the first position port I4 places chamber a in communication with intake port 3 before said chamber a communicates through port I5 and passage 5 with said reservoir, for a reason to appear; in other words, port I4 has a lead on port I5.

A plug I'I is screwed into the housing, preferably at the top thereof, and depending therefrom are numerous filaments I8, preferably of metal, on which oil carried into the reservoir from the primary compression chamber a. may condense. The housing, its said reservoir being otherwise normally closed, has in its depending nipple I9 an outlet 20 affording a seat for a valve 2I whose stem 22 depends from a float 23 within said reservoir and is cut away below the valve so that when the latter is unseated by rise thereof with the floatV oil accumulating in said reservoir may escape. The extent of rise of the iioat and hence of the valve is rendered variable by the nuts 24 screwed on the stem. Onto the nipple is screwed an element 25 which couples with the nozzle a tubular conductor 2B which may include a valve-casing 21 containing a spring-pressed check-valve 28 and which may lead to the crank-case of the engine or any other receptacle in which to recover the oil accumulating in the reservoir.

` In the position of the power piston shown a fresh fuel charge is admitted via ports 3--I4 to primary compression chamber a, and, the charge in secondary compression chamber b being fired (as by a spark-plug 29), said piston descends with compression of said fresh charge in chamber a and then, port I6 coming into communication with the by-pass passage 5, transfer of such charge to chamber b occurs as soon as the head of the piston begins to uncover said passage, followed by delivery of the fired charge at exhaust 4. On the ascent of the power piston (disregarding reservoir c for the meanwhile), as the transferred charge is being compressed in chamber b a vacuum is being formed in chamber a until port I4 coincides with intake 3, when a fresh charge is admitted to chamber a preparatory to the next cycle. Such is the usual operation of engines of this type. In View of the presence of reservoir c and associated parts and also of chamber a-communicating with intake 3 before said chamber communicates with reservoir c when the power piston ascends the operation is' as follows:

As the power piston rises from the position of Fig. 5 to that of Fig. 6 an increasing vacuum is forming in chamber a and also in reservoir c via inhalation port I6. When said piston assumes the position of Fig. 7, where such inhalation port has passed by-pass passage 5 and is hence closed, the vacuum continues to be increased in chamber a whereas the degree thereof so far attained in reservoir c from now on remains constant until as will appear. When the piston assumes the position of Fig. 8 (where inhalation port I4 is beginning to permit a fuel charge to enter chamber a. from intake 3, but exhalation port I5 is not yet positioned to permit flow from chamber a to reservoir c) the fuel begins to'enter chamber a.. Whenthe piston assumes the position of Fig. 9 exhalation port I5 opens and, the pressure in chamber a now being higher than in reservoir c, there is a iiow from the former to the latter through said port. In short, the Vacuum maintained in chamber c serves to draw fluid from chamber a to reservoir c when the pressure in the former is restored by intake 3 and chamber a being brought into communication with each other. Wherefore oil that has found its way up between the movable piston and cylinder and becomes lodged (through port I4) on the fixed piston, as well as some oil which is in suspension in the fresh fuel charge, is deposited in the reservoir. If the latter were put in communication with chamber a before intake of fresh fuel to chamber a, there would obviously be fluid flow from reservoir c to chamber a, to wit, to no purpose. If the reservoir were put in communication with chamber a simultaneously with the intake of fresh fuel to chamber a there might be some fluid flow from a. to c with corresponding deposit of oil in the latter, but to insure a one-direction flow, or an intensified liow from chamber a to the reservoir, and hence as complete as possible scavenging of chamber a of oil, the opening of exhalation port I5 is delayed until the intake and inhalation port I4 communicate.

Assuming that upon the passage 5 being closed by the power piston the pressure in reservoir c ls (however effected) lower than in chamber a, essentially then the invention involves ports as I4 and I5 which respectively being the intake and chamber a, and said chamber and the reservoir c in communication withv each other, with fluid flow to the reservoir. This I claim broadly as well as the fact that in the example the power piston is active in producing a pressure in the reservoir which is ultimately lower than that in chamber a.

The oil conveyed to the reservoir in part flows by gravity to the bottom thereof and in part condenses and accumulates on the filaments I8, then to fall to the bottom of the reservoir. Collecting here it from time to time raises the float valve' 2I--23 and escapes to the conductor 26 and thence to the crank-case or other recovery receptacle. The check-valve prevents its return as an incident of the vacuum formed when thepower piston ascends.

A collar 30 is screwed into the lower end of the skirt of the power-piston body and receives the ends of the wrist-pin and it may have a piston-ring 3I. The collar has an upstanding flange 30a receiving and preventing the expansion of the lower end of the skirt, preferably formed as thin as possible since it is known that the more the displacement of the fixed piston the greater is the efliciency of the engine. In the preferred form the collar is made to have a wedging action on the skirt end as by chamfering the latter, or bevelling the liange, or both, as shown.

To prevent a surfeit of oil attaining the inner surface of the power piston when down and so working up between the power piston and fixed Apiston I provide the former withA a baffle plate 3| closing off communication up through said power piston and arranged below the fixed piston, being penetrated by the standards 1. In the present example this is clamped between the collar 30 and the inside shoulder 8d of the skirt of the body of the power piston.

In engines of this class, as the piston descends andwhen its head passes the by-pass passage 5 to permit the fresh charge to flow from chamber ato chamber ll) there-is likely to be a displacement of oil by the pressure around and in a groove, as 32, existing between the lower piston-ring 8a and sleeve I2 and so out of the exhaust 4,-in other words a loss of lubricant in this way. Hence (Fig. 3) I form the groove with a seriesA of recesses 33 in which some of the oil will be pocketed and hence not responsive to the pressure acting as stated.

In engines of this class there is of course usually some space by which the by-passing is permitted, and lubricating oil may be carried into this space by the fuell charge. But so far as I am aware I am the rst to form this space well-shaped, as reservoir c, so that the oil received therein can collect and be retained against re-ow to the cylinder. Further, according to this invention oil does not enter this space only through a port, as I6, coactive with port 5 in effecting the by-passing, but also through a port, as I5, which permits the oil to enter said space actually when the power piston approaches the end of its intake stroke. Still further the well-shaped space, which may take any form whatever, has discharge means (here the passage of conductor 26) and means to prevent reverse ow through the discharge means (here the check-valve 28). Again, said wellshaped space has means, as the oat valve, to control the flow for discharge through the discharge means.

Having thus fully described my invention what I claim is:

l. In combination, fixed structure including a cylinder, a fixed piston therein and liquid-receiving means having a passage leading from the interior of the cylinder laterally thereof and at one side of the piston and said means being otherwise normally closed, said cylinder having at said side of the piston an intake, and a reciprocatory power piston having a head at said side of the xed piston and a cylindrical skirt fitting between the latter and cylinder, said power piston when moving head-end foremost being adapted rst to maintain said passage closed and having 'inhalation and exhalation ports respectively adapted then to coincide with said intake and passage, whereby, upon the pressure in the receiving means when said passage is so closed by the power piston being below that in the space in the power piston at said side of the fixed piston, there will be fluid flow from such space to said means when said ports so coincide with the intake and passage.

2. In combination, fixed structure including a cylinder, a fixed piston therein and liquid-receiving means having a passage leading from the interior of the cylinder laterally thereof and at one side of the piston and said means being otherwise normally closed, said cylinder having at said side of the piston an intake, and a reciprocatory power piston having a head at said side of the xed piston and a cylindrical skirt tting between the latter and cylinder, said power piston when moving head-end foremost being adapted rst to maintain said passage closed and having inhalation and exhalation ports respectively adapted then to coincide with said intake and passage, the former previously to the latter, whereby, upon the pressure in the receiving means when said passage is so closed by the power piston being below that in the space in the power piston at said side of the fixed piston, there will be iiuid iiow from such space to said means when said ports so coincide with the intake and passage.

3. The hereindescribed engine including, with fixed structure itself including a cylinder, a fixed piston therein and liquid-receiving means having a passage leading from the interior of the cylinder-laterally thereof andat one side of the piston and said means being otherwise normally closed, said cylinder having at said side of the pistonan intake, a reciprocatory power piston having a head at said side of the fixed piston and a cylindrical' skirt fitting between the latter and cylinder, said power piston when moving head-end foremost being adapted iirst to maintain said passage closed and vhaving inhalation and exhalation ports respectively adapted then to coincide with said intake and passage, and means in the first means to condense liquid admitted to the latter.

4. The hereindescribed engine including, with fixed structure itself including a cylinder, a fixed piston therein and a liquid reservoir having a discharge outlet andv also a passage leading from the interior of the cylinder laterally thereof and at one side of the piston and said means being otherwise closed, said cylinder having at said side of the piston an intake, a reciprocatory power piston having a head at said side of the Iixed piston and-a cylindrical skirt tting between the latter and cylinder, said power piston when moving head-end foremost being adapted rst to maintain closed said passage and having inhalation and exhalation ports respectively adapted then to coincide with said intake and passage, and a float valve in the reservoir controlling said outlet. 5.. The hereindescribed engine including, with fixed structure itself including a cylinder, a iixed piston therein and liquid discharge means having a passage leading from the interior of the cylinder laterally thereof and at, one side of the piston, said cylinder having at said side of the piston an intake, a reciprocatory power piston having a head at said side of the fixed piston and a cylindrical skirt tting between the latter and cylinder, said power piston when moving head-end foremost being adapted rst to maintain closed said passage and having inhalation and exhalatio-n ports respectively adapted then to coincide with said intake and passage, and a check-valve in said discharge means yieldingly held seated toward the cylinder.

6. The hereindescribed engine including, with fixed structure itself including a cylinder, a fixed piston therein and liquid discharge means having a passage leading from the interior of the cylinder laterally thereof and at one side of the piston, said cylinder having at said side of the piston an intake, a reciprocatory power piston having a head at said side of the fixed piston and a cylindrical skirt tting between the latter and cylinder, said power piston when moving headend foremost being adapted first to maintain closed said passage and having inhalation and exhalation ports respectively adapted then to coincide With said intake and passage, checkvalve means in the discharge means closable by atmospheric pressure, valve means in the discharge means between the first valve means and the cylinder, and a float in the discharge means having the second-named valve means movable therewith.

'7. The engine set forth in claim 8 characterized by the cylindrical portion of the power piston projecting, in any position of the latter to which it is reciprocated, beyond the fixed piston relatively to the cylinder head and having in the part thereof so projecting beyond the xed piston means forming a circumferential seal with the cylinder.

8. A two-cycle internal-combustion engine including, with fixed structure itself including a cylinder closed at one end and a piston therein, a cylindrical power piston reciprocatory lengthwise of and in the cylinder and having a head between said end and the rst piston and a skirt depending between the latter and cylinder, the cylinder having an exhaust opening arranged to be between said end and head when the latter adjoins the first piston and an intake between said open,- ing and first piston and said structure also including a normally closed liquid-receiving space and having a passage connecting such space with and open to the cylinder interior from approximately the first piston to beyond said head when the latter adjoins said first piston and opposed by the power piston skirt when said head adjoins said cylinder end, and said power piston having in its skirt primary and secondary inhalation ports so arranged that the former port will connect said passage and interior of the cylinder when said head adjoins the first piston and the latter port will connect said intake and cylinder interior when said head adjoins said cylinder end and an exhalation port arranged to connect said passage and cylinder interior when said head adjoins said cylinder end.

9. The combination set forth in claim 8 when characterized by the secondary inhalation port having a lead on the exhalation port when the piston head approaches said cylinder end.

10. An engine of the class described comprising, With xed structure including a base, a cylinder on the base having its lower end open, a fixed piston in the cylinder and standards on the base supporting the fixed piston, a power piston having a head above the fixed piston and a cylindrical skirt depending between the fixed piston and cylinder and below the former, power-transmitting means depending from the power piston, and a baffle plate extending across the skirt between the xed piston and said means and penetrated by said standards.

11. An engine of the class described comprising, with fixed structure including a base, a cylinder on the base having its lower end open, a xed position in the cylinder and standards on the base supporting the fixed piston, a power piston having a head above the xed piston and a cylindrical skirt depending between the xed piston and cylinder and below the former and having an inside downwardly facing shoulder near its lower end, power-transmitting means depending from the power piston and including a collar screwed into the lower end of said power piston below said shoulder, and a baffle plate clamped between said collar and shoulder and penetrated by the standards.

12. A power-piston for an engine of the class described comprising a hollow cylindrical body having a head and a circumferential groove in its head formed with pockets closed off from the interior of the piston and arranged in a series extending lengthwise of the groove.

GEORGE EXEL.

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