US2032578A - Rotary valve - Google Patents

Description

F. T. IRGENS ROTARY VALVE March 3, 1936 Original Filed March 17, 1930 3 Sheets-Sheet 1 INVENTOR 7 44/14 7 ATTORNEYS F. T. IRGENS -ROTARY VALVE 2 March 3, 1936.

Original Filed March 17, 1930 5 Sheets-Sheet 2 ATTORNEYS EL? E.

March 3, 1936. F. 1:. IRGENS 2,032,578

ROTARY VALVE Original Filed March 17, 1930 3 Sheets-Sheet 3 /5 INVENTOR M MM ATTORN EY5 Patented Mar. 3, 1936 ROTARY VALVE Finn T. Irgens, Milwaukee, Wis., assignor to 0ut-. board Motors Corporation, Milwaukee, Wis a corporation of Michigan Original application March 17, 1930, Serial No.

436,287, now Patent No. 1,936,841, dated November 28, 1933. Divided and this application August 12, 1931, Serial No. 556,518

4 Claims. (01. 123-73) This invention relates to improvements in rotary valves and has particular reference to a novel and improved rotary valve mechanism which controls the flow of mixture to the crank case of a two-cycle engine, and also in effect varies the volumetric capacity of the crank case at different points of the cycle.

This is a divisional application of my application, Serial No. 436,287, filed March 17, 1930, for Internal combustion engines upon which Patent 1,936,841 issued November 28, 1933.

'It is the primary object of the invention to improve the volumetric eff ciency of two-cycle engines While avoiding difficulties heretofore experienced in the way of imperfect mixtures which have resulted from previous attempts to increase crank case compression.

It has become standard practice in two-cycle engine construction to limit the crank case capacity as much as possible by'v filling the crank case almost completely with the cranks and associated parts. ciency has been improved due to the increased crank case compression, but there has been a corresponding decrease in the efficiency of combustion resulting from the high velocity at which the compressed gases have been transferred to the combustion chamber, which they must necessarily enter before the burning charge has been completely scavenged.

In the practice of the present invention I not only use a rotary valve for the purpose of prolonging and more adequately controlling communication between the crank case and the carburetor, but I further accomplish a very important result in designing my rotary valve to provide an expansion chamber which is made to communicate with the crank case and transfer port prior to and during transfer of gases from the crank case to the combustion chamber. The additional capacity thus provided receives a portion of the highly compressed gases in the subpiston space, and not only maintains such gases more immediately adjacent the point of delivery to the cylinder, but also reduces the sub-piston compression to an extent such that the flow of gases to the cylinder is slower and more uniform, thereby promoting better and cleaner scavenging with fewer eddy currents and a much better and. more highly combustible mixture remaining in the combustion chamber.

While I have referred to crank case compression, it will be observed that there is very little compression space in the crank case, and that actually compression occurs quite largely in the By this means volumetric effilower ends of the respective cylinders beneath the pistons operating therein; To avoid loss of pressure which would be occasioned by transferring gases between the respective cylinders, I prefer to provide each cylinder with its own separate carburetion and valve.

Another object of the invention relates to the provision of means whereby the rotary valve is permitted to operate at substantially uniform rates of rotation notwithstanding periodic or cyclic variations in rate of rotation of the crank shaft and associated parts.

In the drawings:

Figure 1 is a plan view of a two-cycle twocylinder opposed engine embodying this invention, one of the cylinders and associated valve mechanism being shown in axial section.

Figure 2 is a vertical axial section to the engine shown in Figure 1. 1

Fig. 3 is a rear elevation thereof.

Figure 4 is a fragmentary detail similar to a portbn of Figure 1, showing the piston at the end of its compression stroke.

Figure 5 is a view taken in section in the plane indicated at 55 in Figure 4.

Figure 6 is a view taken in section in the plane indicated at 66 in Figure 4.

Figure 7 is a detail view taken in section in the plane indicated at l'l in Figure 2.

Like parts are identified by the same reference characters throughout the several views.

The invention has been shown, by way of illustration, applied to a two-cycle, two-cylinder opposed engine of an outboard motor, but obviously it may be employed in connection with two-cycle engines having a different number of cylinders and organized for different purposes.

In this exemplification of the invention a sleeve or so-called shaft housing member In supports the crank case I I upon which are mounted the respective cylinders l2, In the top and bottom of the crank case H are bearings for the crank shaft l5, at the upper end of which is the usual fiy wheel Hi. It will be noted that the crank disks l8, pins l9, connecting rods 20, and

connecting rod bearings 21 are so designed as to leave a very small amount of gas capacity in the crank case, the object being to fill the crank case as nearly as possible.

The cylinders H are provided in the usual way with exhaust ports at 22 communicating with' manifolds 23 and muffler 24. Each cylinder has inder above and below the piston 26 therein. i

ploy the resilient pinion mounting illustrated.

The piston preferably comprises a hollow body open 'at 21 for intermittent communication with the exhaust port 22, and having an inclined lower face at 28 for guiding gases to and from the compression space below the piston.

Controlling the admission of mixture to the inlet 'and,transfer ports '25, is the rotary valve mechanism which comprises the particular su ject matter of the present invention.

. Each cylinder is provided with an integral for ward extension at 30, of which the cylindrical bore communicates with the cylinder through ports 25. These bores are capped at their-outer ends by closures 3|, each of which comprises a carburetor having a flaring air inlet mouth at 32, a float chamber at 33, a jet at 34, and a throttle valve at 35.

The valves mounted in the bores of the respective cylinder extensions 30 comprise sleeves 36, each of which is ported at 31 and 38, the latter port being placed in direct communication with the air inlet valve 32 by means of a pipe 39 which is cast integrally with sleeve 36, and is formed to provide an axially disposed inlet portion at 40, and a radially disposed discharge portion at 4|. The discharge portion 4| of pipe 39 is joined to the margin of the sleeve about the port 38 therein. I

Each such sleeve is closely fitted to rotate within its respective bore, and each is provided with a' shaft extension 43 upon which is mounted a bevel gear 44. The two bevel gears 44 in the present construction receive motion from a bevel pinion 45, flexibly keyed to a jack shaft 46. The jack shaft in turn is driven by a spur gear 41 from a complementary spur gear 48 on the crank shaft. The hub of this latter gear extends into the upper crank shaft bearing as shown in Figure 2. The jack shaft 46 may constitute a timer shaft provided with the interrupter mechanism shown at 43.

The flexible connection of the driving pinion 45 to the jack shaft or timer shaft 46, is best shown in Figure '7. Shaft 46 is provided with a slot at 50 in which the resiliently flexible spring key 5| is held by a cross pin 52. The free end of the resilient key 5| has arms 53 which project from the slot 50 into engagement with suitable grooves in the pinion 45, as shown in Figure 2.

The result is a construction which permits pinion 45 a limited degree of independent movement with respect to the shaft 46 upon which .it is mounted.

It will be understood that the two cylinders in this type of engine fire simultaneously, and the energy developed in the expansion stroke must be used in the subsequent compression stroke. As a result, there is an appreciable cyclic change in speed of crank shaft and fly wheel, and in order to avoid transmitting this varying rate of rotation through the pinion'45 and driven gears 44 to the rotary valves, I may, if I so desire, em-

In practice, the movement of the piston to the position in which it appears in Figure 4 not only compresses the combustible charge in the outer end of the cylinder, but draws a fresh charge through the carburetor and the rotary valve into the inner end of the cylinder next to the crank case. As above noted, the charge for each given cylinder is drawn directly into the base thereof, thus avoiding any necessity for the transfer of gases across the crank case, in which the space is purposely very limited.

It will be noted from an inspection of Figure 4 with cylinder port, 25.

that the capacity of the space beneath the piston is at a minimum during the stroke which sucks the fresh charge therein. The rotation of the valve sleeve 36 has brought pipe 39 through a position of registry with the inlet of transfer port 25 through. which the carbureted air orcombustible mixture has been entering the compression space. The remainder of sleeve 36 iscompletely cut off from communication with this space. Practically the complete displacement of the piston, therefore, is effective to draw combustible mixture into the inner end of the .cylinder in accordance with the most approved twocycle practice.

During the expansion stroke of the piston toward the position in which itis shown in Fig. 1, the valve sleeve 36 is caused to rotate to the position shown in Figure 1 whereby its pipe member 39 is wholly out off from communication The cylinder port 25 has now -been placed in communication, through sleeve port 31, with the receiver in the interior of the valve sleeve 36 into which a large portion of the combustible mixture has been forced by the descending piston 26. Thus, instead of holding under high compression the large quantity of gas drawn into the restricted sub-piston compression space, I have already caused such gas to start on its movement toward the cylinder, and I am holding it under reduced "compression in a space of very much larger capacity than,could have been provided in the cylinder and transfer port alone.

As a result of this construction the transfer of mixture to the cylinder, and the consequent scavenging of the exhaust gases from the cylinder, takes place more smoothly than has been possible in any two-cycle engine having a like efflciency of mixture intake. The power of the engine is greatly increased by this means of controlled variation of the capacity of the subpiston compression space and transfer port, whereby such space is at a minimum during the compression stroke, and is at a maximum during the expansion stroke and transfer.

As an example'of the timing of the rotary valve mechanism disclosed, I shall refer to a particular engine embodying the invention in which the transfer port 25 communicates almost continuously with one or the other of ports 31 and 36 of the valve. As soon as the piston 26 moves upwardly sufficiently to cut off communication betweenthe transfer port and the combustion chamber, port 38 moves into initial registry with transfer port 25 to admit carbureted air to the sub-piston compression space. Port 38 continues open until the piston has started downwardly on its expansion stroke to a position representing approximately'25 degrees of crank rotation past top dead center. At this point port 38 closes and port 31 moves into registration with transfer port 25, thereby allowing the mixture compressed below the piston to pass into the receiver within the valve sleeve 36 until the piston has completed its expansion stroke and moved upwardly to a point where the transfer of gas has ceased. I

The organization disclosed will be found useful in many internal combustion engine constructions using a means of compressing mixture in advance of delivery to the combustion chamber. It will, however, be found particularly valuable in the type of two-cycle engine disclosed.

I claim:

1. The method of charging a two stroke cycle includes the storage of gas preliminarily compressed beneath the piston, the decrease of pressure of the stored gas below that which would otherwise be produced by the piston and the delivery of the stored gas to the cylinder at such reduced compression.

2. The method of charging a two stroke cycle internal combustion engine in whichthe piston movement draws gases into the transfer port, compresses the gases therein and displaces the gases through the transfer port, subject to control of the piston, into the working cylinder, which method includes restricting the capacity of the transfer port during the admission of gases beneath the pistomwhereby to increase the pressure difierential produced by a given piston displacement, and subsequently increasing the capacity of the transfer port for storage of gases therein, and delivery of gases therefrom to the working cylinderat a pressure differential relatively reduced in pr portion to said piston displacement, whereby to maintain a relatively high volumetric efficiency while avoiding undue turbulence of discharge of the gases into the wor cylinder.

3. The method of charging a two stroke cycle internal combustion engine having crank case compression and transfer fromthe crank case to the combustion chamber, such method comprising the cyclic variation of the fluid capacity of the crank case from a relatively small capacity during the intake stroke to a relatively large capacity during transfer.

' 4. The method of charging a two stroke cycle internal combustion engine having sub-piston compression and alternate intake and transfer FINN '1'. means,

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