US 2399743 A
Description (OCR text may contain errors)
May 7, 1.946.
c. N." KAHL Filed Aug.- 28, 1944 ENGINE 2 Sheets-Sheet l C. N. KAHL May 7, 1946,
ENGINE Filed Aug. 28, 1944 2 Sheets-Sheet 2 DmEOU m0 aOP Patented May 7, 1946 ENGINE fCharles N. Kahl, Jacksonville; IIL, assignor of'onehalf to Lee.A.iSullivan, Jacksonville, Ill.
Application Angustias, 1944,'s'erial No. 551,496"
Y ilfClaim. (Cl. 12S- 65) This invention, relates to improvementsin twocycle engines. employing a turbine-driven superchargenandis a continuationfin-part of mycopending applications SeriaLNo. 401,243 filed July v, 19,41, and Serial No. 448,989 led June 29, 1942, both for Engines.
in the ordinary two-cyclerengineonly a single exhaust port is provided in each. cylinder. as a means to perform the dual functionloi` pressure `exhausting and scavenging. 'I'urbine-,drivensnperchargers cannot be successfully operated' Ain conjunction with two-,cycle engines having such a single exhaust port becausethe backpressures formed bythe turbine-driven supercharger interferes with proper evacuation of exhaust gases. The coolair forced into the cylinder through the intake valve mixes andlcools the residual gases remaining in the cylinder after the high pressure gas .has escaped through the .exhaust port. Such cooled gases adversely affect-the operation of the turbine-driven superchargerhccause such admixture-of cooled gases isforced into the supercharger and, therefore, lowersthe temperatures therein.
It was to overcome this and other disadvantages accruing in Ya single l. cxhaustported twocycle engine employing a turbine-driven superchargerthat the present invention was conceived.
The main objects of this inventionarc -toprovide an improved and more eicient two-cycle engine employing a-turbine-drivensupercharger; to provide such an enginezwherein each cylinder therein includes a high pressure exhaust port whereby to allow `the high pressure .gases-only in the cylinder to be evacuated `therefrom and therethrough; to provide a high pressure exhaust port in each cylinder of such an engine whereby the products of comlcnistion are evacuatedffrom the cylinder at` their lhighest,temperature 4and a low pressure exhaust port in. each` cylinder for scavenging;.to provide an engine of this character wherein back pressures are eliminated because or provision being made for the openinggandathe closing of a high pressure exhaust port-independently and exclusively Y of `.thecpening and closing complete cycle ofpopening and then Lclosing, the high pressure exhaust port is eflectedbeiore the other is opened; to providel an engine ofythis character wherein each of thev cylinders is vprovided with a high pressure exhaust :port which is adapted to open and expel the-high power-ex.- haust gases from the cylinder and thenlce closed before the intake port and scavenging port are opened; to provide an engine of thischaracter '45 of the low .pressureexhaust port, whereby the wherein the eiiiciency of lthe superchargerl is greatly increased because the exhaust gases are expelled. from the cylinder at a higher temperature througha high pressure exhaust port and delivered to the supercharger before theyhave had an opportunity to become cooled; toprovide an engine of this character wherein approximatelY to 80% of the products of combustion formed in the` cylinder on each stroke is exhausted directly to asupercharger and then the exhaust `port closed before the intake port and scavenging port are opened; andl to provide an engine of this character which is simple in construction and more-eicient in operation.
An illustrativeembodiment is shown in the accompanying drawings in which:
Figure 1 `is a vertical` cross-sectional View through a cylinder embodying a construction in accordancewith my invention and showing the piston at Athe bottom dead center of its stroke; the intake port and the scavenging port being open.
Fig. 2 is a View similar to Fig. 1 but showing the piston` starting `on itsV upstroke with all the ports closed.
Fig. 3 is a view similar to Fig. 1 but showing the 4piston at the upper end of its stroke, the ports all closed and the arrows indicating emission of the fuelintov the upper end of the cylinder.
Fig. 4 is a View similar to Fig. 1 showing the piston on itsdownstro-ke with ports all closed.
Fig. 5 is a `view similar to Fig. 1` showing the piston continuingon its down stroke, `the high pressure exhaust being opened and the other ports being closed.
Fig. 61s a diagrammatic representation illustrating the various positions of the piston and 4piston sleeve during a complete 360 rotation of the crankshaft with respect to their various Vpositions to the three ports in thecylinder.
Referring in detail to the drawings, the engine block or frame I contains the usual water jackets 2 iorthe' cylinder 3, a-ir passageways or chambers 4, an exhaust2 port 5,hereinafter referred to as "the low pressure `exhaust port, and an intake port 6. vIn additiontofthe above I have added a high pressure exhaust port 1 located between the intake Vport E and the low pressure exhaust port ii, the purpose of which will be hereinafter explained.
Each cylinder 3 contains apiston 8, of the type disclosed in my two above referred toco-pending applications, which is provided with a roller bearing Sdesigned andfarrangedifor enacting engagement 4vwith the cam track t0 of the wabble cam II. A reciprocating valve sleeve I2, of the character disclosed in my above referred to co-pending application Serial No. 448,989, encompasses the piston 8 and lines the cylinder walls.
The sleeve I2 is provided with a roller bearing I3 for coactive engagement with the sleeve track I4 of the wabble cam Il, and a series of ports I5 and I6. As fully explained in my aforesaid co-pending application Serial No. 448,989, the valve sleeve I2 is designed to travel slightly ahead of the piston travel regardless of the direction of travel of the piston 8 (upstroke or downstroke) because the sleeve track I4 leads the piston track Ill by a few degrees.
A supercharger turbine (not shown) is arranged to be connected to the high pressure exhaust port 'I in the usual and. same manner as a supercharger is connected to the usual exhaust port; hence it is not necessary to illustrate the same.
A complete cycle of operation of this engine is comprehensively shown in the drawings Figures 1 to 5. In Fig. l, the piston is at its bottom dead center; hence the intake port 6 and the port I5 are in registry with each other and air forced into the cylinder. At the same time the low pres sure exhaust port 5 and the port I5 are in registry with each other and'scavenging of the low powered exhaust gases is taking place; that is, the fresh air forces the remaining,r burned gases from the cylinder. It is to be noted that the high pressure exhaust port 'I is completely closed off from the cylinder.
In Fig. 2 the pistonis on its upstroke, as is the valve sleeve I2; therefore, the ports I5 and I ii are out of registrywith the low pressure exhaust port 5, the intake Port 6, and high pressure exhaust port 1.
In Fig. 3 the piston has reached the top of its upstroke as has the valve sleeve I2, and as shown therein, the ports l5 and I6 are out of registry with the low pressure exhaust port 5 and intake port 6. The piston being at the top of its stroke, fuel is automatically injected into the top of the cylinder through the fuel nozzle I'I and the hot gases expand against the piston forcing it downward on the power stroke.
In Fig. 4 the piston has started on its downward stroke and it is to be noted that all of the ports are out of registry with the sleeve ports.
In Fig. 5 the piston is still on its downstroke and the top thereof is approximately opposite the high pressure exhaust port 1. The valvesleeve has descended to a point whereby the ports I5 are in registry with the exhaust port 1. At this point the high powered exhaust gases rush out of the cylinder through high pressure exhaust port 'I and directly into the supercharger.
As the piston and sleeve descend further, all of the ports will be out of registry until the piston substantially reaches bottom dead center of its stroke, wherein the position of the piston and sleeve will be in the position shown in Fig. 1. There as pointed out heretofore the ports I5 are in registry with the intake port 6 and the ports I6 are in registry with the low pressure exhaust Dort 5.
This cycle of operation is diagrammaticaliy shown in Fig. 6 and thoroughly illustrates the reason why the high pressure exhaust port is only in registry with the ports I5 on the downstroke of the piston. It will also be seen that the high pressure exhaust port is opened to the cylinder only a fraction of the length of time the intake port and the low pressure exhaust port are opened for the purpose of scavenging and admitting fresh air to the cylinder.
Therefore, it should be readily apparent that only the high temperature exhaust gases are evacuated from the cylinder through this port. These gases are fed directly into the supercharger turbine before the burned gases have had an opportunity to become cooled by the admission of air into the cylinder. Such being the case, the exhaust gases are fed into the supercharger turbine at substantially the existing temperatures of the gases at the time of uncovering the port. The supercharger, therefore, having mission of lower temperature gases or gases mixed with cool air, will operate at greater increased efficiency. Since there is no communication between the high pressure exhaust and the scavenging exhaust or the air intake, back pressure from the supercharger cannot impede either scavenging or intake charging.
Since the supercharger is provided with exhaust gases at abnormally high temperatures (even up to 1700" F. and pressures to 200 pounds) greater power is developed in the turbine-driven supercharger than is required for scavenging and supercharging. It is readily apparent that this power may be efficiently fed back to the engine drive shaft through suitable gearings and hydraulic couplings as will be readily understood by those skilled in this art.
It should also be apparent to those skilled in the art that approximately 70 to 80 of the products of combustion formed in the cylinder on each stroke may be exhausted directly to the supercharger by employing the construction illustrated. As will be seen from Fig. 6 on the upstroke of the piston 8 and the sleeve I2 after they each reach bottom dead center, (the piston at and the sleeve at 188) the sleeve travel will be slightly behind the piston travel; therefore, the intake port will be opened a short period of time after the top of the piston has reached a point opposite the upper edge of the intake as the ports I5 in the sleeve will only be substantially half closed. The air flowing in the cylinder through the intake port will, of course, be of diminished quantities, until the sleeve I2 completely covers the intake port 6.
It is to be understood that the piston covers sleeve port I5 before the port I5 registers with or passes the high pressure exhaust port '1.
By this procedure it is apparent that more air is forced and packed into the cylinder than was possible heretofore because this additional air is admitted to the cylinder after the scavenging or low pressure port 5 has been closed as the port I6 has moved out of registry with the port 5.
It is to be understood that numerous details of the construction shown and described may be altered or omitted without departing from the spirit of this invention as dened by the following claim:
In an engine of the class described comprising a cylinder, a piston in said cylinder, a valve sleeve in said cylinder positioned between said piston and the walls of said cylinder and having axially spaced upper ports therein located adjacent the upper end of said sleeve, axially spaced lower ports located adjacent the lower end of said sleeve, a low pressure exhaust port in one end of said cylinder, an intake port in the other end of said cylinder, a high pressure exhaust port in said cylinder located between said low pressure exsaid cylinder. said ports in said sleeve substantially simultaneously register with said low pressure exhaust port and said intake port fo-r communication with the interior of said cylinder towards the end of the power stroke of said piston, and while said high pressure exhaust port is closed. CHARLES N. KAHL.