US2443838A - Two-cycle crankcase compression engine - Google Patents

Description

June 22, 1948. .1. w. SMITH TWO-CYCLE CRANKCASE COMPRESSION ENGINE 3 Sheets-Sheet 1 Filed Jan. 2, 1946 INVENTQR Jay W aim/#7 ATTORNE YS June 22, 1948. J. w. SMITH 2,443,838

TWO-CYCLE CRANKCASE COMPRESSION ENGINE Filed Jan. 2, 1946 3 Sheets-Sheet 2 FY55: 7. 37 Hg :2

INVENTOR Jay V/m/fh qemil June 22, 1948. J. w. SMITH 2,443,838

TWO-CYCLE CRANKCASE COMPRESSION ENGINE Filed Jan. 2, 1946 3 Sheets$heet 3 IN V E NTO R Jay mas/mm Patented June 22, 1948 Jay W. Smith, Algonac, Micln, Craft Corporation, Algonac,

tion of Delaware asaisnor to Chris- Micln, a corpora- Application lanuary z, 1946, Serial No. 838,643

before being admitted to the combustion chambers. As the fuel mixture flows along this rather extensive path, raw fuel, in the mixture has a tendency to drop out of suspension before the mixture reaches the combustion chambers and,

, as a result, the predetermined balance of the mixture is disturbed. It is well established in this art that the proportion of the fuel and air in the mixture is critical and a loss of fuel not only affects the performance of the engine, but also reduces the eificiency of the latter.

With the above in view, the present invention has as one of its objects to reduce to a minimum the distance the fuel mixture is required to travel from the carburetor or mixing chamber to the of the engine. In accordance with this invention, an intake manifold for fuelmixture is supported on the engine in a position to supply fuel mixture directly to the inlet ports formed in the engine cylinders adjacent the outer ends of the latter.

Another feature of this invention is to provide an internal combustion engine having a. cylinder block formed with a space directly opposite the inlet ports in adjacent cylinders and having means on the intake manifold coacting with a part of the engine block between adjacent cylinders to divide the space into twoindependent chambers.

Still another objector this invention is to provide an intake manifold having a fuel mixture supply, passage communicating with the chambers adjacent the cylinders through branch passages and having resilient valve members respectively secured thereto at opposite sides of the dividing means for controlling the flow of fuel cylinders mixture through the branch passages.

A further object of this invention is to provide an intake manifold having wall portions at opposite sides of the dividing means which taper outwardly from the dividing means so as to direct the fuel mixture laterally throu hout the width of the chambers and having reed type valve members respectively secured to the tapered wall portions for normally closing the branch passages.

is admitted to the 4 Claims. (Cl. 123-43) The foregoing -as-well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein- Figure l is a side elevation of an internal combustion engine embodying; the features of this invention;

Figure 2 is a sectional view taken substantially on the plane indicated by the line 2-2 of Figure 1;

Figure 3 is an end elevation, partly in section, of the internal combustion engine shown in Figure 1;

Figure 4 is a end elevation of the intake manifold for the internal combustion engine.

Figure 5 is a side elevation of the intake manifold shown in Figure 4; t

Figure 6 is a cross-sectional view taken substantially on the plane indicated by the line 8-6 of Figure 4; and

Figure 7 is a fragmentary sectional. view through a modified construction of intake manifold.

Referring first to the embodiment of the invention shown in Figures -1 to 6 inclusive, it will be noted that the reference character l0 indicates a multi-cylinder two cycle internal com-- bustion engine of the liquid cooled type. For the purpose of illustrating the present invention, a two cylinder engine is selected but it will be understood as this description proceeds that. the invention is applicable to internal combustion engines having more than two cylinders.

. With .the above in view, particular attention is directed to Figures 1 to 3 inclusive of the drawings, wherein it will be noted that the internal combustion engine i0 comprises generally a cylinder block I i, a crankcase l 2 and a cylinder head l3. The crankcase I2 is detachably secured to the block Ii by means of studs l4 and cooperates with the adjacent portions of the block to form bearings I5 in which the crankshaft i6 is journailed.

The cylinder head l3 forms a closure for the outer ends of the cylinders i'l, formed in the block H in juxtaposition to one another, and studs iii are provided for detachably securing the cylinder head to the block, In eccordance with conventional practice, a pair of combustion chambers iii are formed in the cylinder head and respectively register with the two cylinders [1.

Each cylinder is lined with a tube 20 formed of a wear resisting material and a piston 2| is formed on the shaft IS in spaced relation to each other axially of the shaft. One of the cranks is indicated in Figure 3 of the drawings by the reference character 22 and is arranged approximately 180 from the other crank (not shown), which is connected to the piston in the next adjacent cylinder. to the respective cranks by means of rods 28 and the arrangement is suchthat when .one piston is on its suction stroke, the next adjacent piston is on its compression stroke. It will be understood that when the pistons are moved on their respective suction strokes, fuel mixture is drawn into the crankcase.

As is usually the casein two cycle internal combustion engines, the cylinders are formed with inlet and exhaust ports which are controlled by the pistons in the cylinders. As shown in Figure 2 of the drawings, the cylinder block ii is formed with a space 24 opposite the cylinders i7 and this space communicates. with the interior of the cylinders through the medium of inlet ports 25 formed in the adjacent side walls of the cylinder intermediate the ends ofthe latter. It' will also .be noted from Figure 2 of the drawings that the cylinder block H is formed with a space 26 at the opposite sides of the cylinders I1 and this space communicates with the interior of the cylinders through the medium of exhaust ports 21. A cap 28 is removably secured to the cylinder block Ii and cooperates with the space 26-to form an exhaust manifold for discharging the products of combustion out of the engine.

Fuel mixture is supplied to the space 24 by means of a carburetor 29 and an intake manifold 30. The carburetor 29 is of conventional construction and serves to mix fuel and air in the proportions required to obtain efiicient operation of-the engine. The manifold 30 has a cylindrical body portion 3i, which is sleeved in an opening 32 formed in the outer wall of the cylinder block opposite the inlet openings 2-5 and a radially outwardly extending flange 33 is formed on the body 3i for abutting engagement with the outer surface of the cylinder block surrounding the opening 32. An annular sealing gasket 34 is provided between the inner surface of the flange 33 and the adjacent surface of the cylinder block to prevent the escape of fuel mixture from the space 24. Suitable studs 35 are provided for detachablyksecuring the manifold 30 to the cylinder b no The inner surface of the manifold 30 is formed with a diametrically extending rib 36 having a flat surface 31 which cooperates with a corresponding flat face 38 formed on the block between adjacent cylinders I! to divide the space 24 into two chambers 39 and 40. The surface to surface contact between the rib 36 and adjacent part of the cylinder block provides a seal which prevents the escape of fuel mixture from one chamber to'the other.

Referring now more in detail to. Figure 6 of the drawings, it will be noted that the manifold has a Venturi-shaped passage. which communicates withthe carburetor to receive fuel mixture from the latter and is formed with branch passages 42 and 43. The branch passages 42 and 43 respectively communicate with the chambers 39 and 40 at opposite sides of the dividing rib 36 on the manifold. In this connection, attention is directed to the fact that the inner wall of the manifold tapers outwardly from opposite sides of the rib 36 so that fuel mixture entering the The pistons are connected.

chambers from the branch passages is directed laterally across the chambers.

The branch passages 42 and 43 are normally closed by reed type valve members 44 and 43. The valve members are in the form of spring metal strips having corresponding ends ,secured to the manifold and having the opposite ends respectively overlapping the delivery ends of the branch passages. The opening movement of the valves is restricted by means of rigid backing members 48, which are also secured to the manifold. As shown in Figure 4 of the drawings. the same fastener elements 4'! are employed for securing the valve and backing members to the manifold.

The above construction is such that when the pistons 2| in the cylinders I! are in their respective suction strokes, the valves are opened by the suction created in the chambers 39 and 40. As a result, fuel mixture from the carburetor 29 is admitted to the chambers and flows from the chambers through the inlet ports 25 into the cylinders. It is important to note that the delivery ends of the branch passages in the manifold are so closely related to the inlet ports 25 in the cylinders that the fuel mixture may be considered to pass directly from the intake manifold into the cylinders. This is highly desirable in that very little opportunity exists for raw fuel to fall out of suspension from the fuel mixture before the latter is introduced into the cylinders. Thus, the fuel mixture introduced into the cylinders retains the specified proportions of fuel and air which are essential in order to obtain efiicient engine performance. 7

As the pistons 21 travel on their respective compression strokes, the products resulting from previous combustion of the fuel mixture are first discharged from the cylinders through the exhaustports 21 and then the fuel mixture is compressed in the combustion chambers l9. This fuel mixture is ignited by suitable spark plugs 48, which are secured to the cylinder head l3 in the usual manner.

The embodiment of the invention shown in Figure 7 of the drawings illustrates a manifold 50 differing from the manifold 30 in that the inner wall of the manifold at opposite sides of the rib 33 is straight instead of tapered, and the supply passage 5| is not provided with a venturi. The remaining structure is substantially the same as previously described and the same reference characters are used to indicate corresponding parts.

It has previously been stated that the present invention is not limited in its use to two cylinder engines. In this connection, it will be noted that in the event it is desired to equip a four cylinder engine with the present invention, the manifold and corresponding parts previously described are merely duplicated for the other pair of cylinders. This is true for each pair of cylinders added, and therefore, reservation is made to incorporate the principles of this invention in internal combustion engines regardless of the number of cylinders.

What I claim as my invention is:

1. An internal combustionengine having cylinders arranged adjacent each other and having inlet ports for fuel mixture in one side wall of the cylinders, a block in which the cylinders are formed having a space opposite the inlet ports in said cylinders, an intake manifold extending into said space through the outer wall of the block and having an intermediate portion coacting with a part of the block betweenadjacent cylinders to divide said space into two bers, said manifold further having passages therethrough which respectively communicate with the chambers, and valve members on the manifold at opposite sides of .the dividing portion for controlling the flow of fuel mixture to said chambers.

2. An internal combustion engine having cylinders arranged adjacent each other and having inlet ports for fuel mixture in one side wall of the cylinders, a block in which the cylinders are formed having a space opposite the inlet ports in said cylinders, an intake manifold extending into said space through the outer wall of the block and having an intermediate portion coacting with a part of the block between adjacent cylinders to divide said space into two independent chambers, a Venturi-shaped passage in the manifold having the delivery end respectively communicating with the chambers at opposite sides of the dividing portion through branch passages, and valve meansfor independently controlling the flow of fluid mixture through said branch passages.

3. An internal combustion engine having cylinders arranged adjacent each other and having inlet ports for fuel mixture in one side wall of the cylinders, a block in which the cylinders are formed having a space opposite the inlet ports in said cylinders, an intake manifold extending into said space through and having an intermediate portion coacting with a'partof the block between adjacent cylinders to divide said space into two independent chambers, a passage in the manifold respectively communicating with said chambers at opposite sides of the dividing portion through branch passages, 9. Diston slidably supported in each cylinder and operable to control said inlet ports, and resilient valve members respectively secured to the manifold at opposite the outer wall of the block' sides of the dividing portion for independent chami said branch passages.

4. An internal combustion engine having cyl- "inders arranged adjacent each other and having inlet ports for fuel mixture in one side wall of the cylinders. a block in which the cylinders are formed having a space opposite the inlet;- ports in said cylinders, an intake manifold extending into said space through the outer wall of the block and having an intermediate portion meeting with a part of the block between adjacent chamberssaid manifold having walls at opposite sides of the dividing portion which taper outwardly from the dividing portion, es in the manifold r espectively communicating with the chambersfthrough said tapered walls, and resilient .valve members respectively secured to the tapered walls and normally closing said passages.

- JAY W. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES Pxrnm's

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