US2103974A - Supercharging mechanism for diesel engines - Google Patents

Description

B. LOEFFLER SUPERCHARGING MECHANISM FOR DIESEL ENGINES 2 Sheets-Sheet 1 Filed June 4, 1935 INVENTOR. flruna laefilar,

ATTORNEYfl Dec. 28, 1937. B. LOEFFLER 2,103,974

SUPERCHARGING MECHANISM FOR DIESEL ENGINES Filed June 4, 1955 2 Sheets-Sheet 2 INVENTOR. Brazw 1406111121;

Patented Dec. 2 '1937 PATENT OFFICE.

SUPERCl-IARGING MECHANISM FOR DIESEL ENGINES Bruno Loeflier, Plainfield, N. J assignor to Mack Manufacturing Corporation,

Delaware a corporation of Application une 4, 1935,- Serial No. 24,824-

3 Claims.

The present invention relates to Diesel engines and embodies, more specifically, an improved supercharging mechanism by means of which additional air may be introduced into the engine during predetermined periods of operation thereof. It is well known that the power output of 2.

Diesel engine varies directly as the amount of air introduced thereto, the amount of fuel which is burned being dependent upon the amount of air supplied to support combustion. The power output of Diesel engines has heretofore been increased by providing supercharging mechanisms to supply the total air introduced into the ,engine at an increased pressure. The objection to this form of supercharging lies primarily in the relatively great cost thereof due to the power required to compress'and direct the entire air supply into the engine;

It is known that, during the normal operation of a Diesel engine, and where supercharging mechanism is not provided, only about eightyfive per cent. of the air which wouldnormally be directed into the engine is available by reason of the suction effect of the piston and other losses due to friction, etc. In order that this loss of substantially fifteen per cent. may be retrieved,

and substantially one hundred per cent. of the air normally available be supplied to support combustion, the present invention provides a mechanism for introducing a volume of air corresponding to such loss at the proper. time during the engine operation. This additional air-is supplied through a separate channel and introduced into the engine in a particularly advantageous fashion, as will be apparent presently.

It is a further object of the invention to provide a supercharging mechanism wherein additional air may be supplied to the engine during predetermined periods of operation thereof, the means for supplying the air'being of such characteras to introduce as much air as possible during the time available for the introduction thereof during certain periods of operation of the engine.

A further object of the invention is to provide a supercharging mechanism wherein additional. I.

air may be introduced and supplied into the cylinder in such fashion as to supply the loss of air due to wire drawing through the inlet port upon closing movement of the air inlet valve.

A further object of the invention is to provide additional, or supercharged, air may be introduced into the cylinder.

In the construction shown in the accompanying drawings, the invention is attained by the provision of an engine having ahead in which combustion and air chambers are formed to communicate with the engine cylinder, the air chamber being formed to receive supercharged air from an external source, in addition to the fuel and air mixture which is directed into the combustion chamber during the compression stroke of'the piston. y

Further objects, not specifically enumerated above; will be apparent as the invention is described ingreater detail in connection with the accompanying drawings, wherein Figure 1 is a schematic illustration of a portion of the head of a Diesel engine embodying features of the present invention;

Figure 2 is an enlarged view in sectiomtaken through the combustion and air chamber shown in Figure 1, and showing the elements of the present invention in greater detail; I

Figure 3 is a diagrammatic illustration of the manner in which air is introduced into the air chamber, the illustration comprising a valve lifttime curve;

Figure 4 is a diagrammatic representation ofv the inlet and exhaust cycles of operation of an engine inwhich is incorporated the present invention;

Figure 5 is a plan view showing the cylinder head of the mechanism shown in Figure 1, illustrating. the relative location of the engine valves.

' 1 With reference to Figure 1, a Diesel engine is illustrated at Ill and provided with a head ll. The engine is formed with a cylinder [2 with which a combustion chamber l3 communicates,

the combustion chamber in turn communicating through a port It with an air chamber l5 which may be formed in a suitable housing l6 or which may constitute partof the engine head. The 1 which is adapted to align with port I4 to establish communication between the combustion chamber l3 and the air chamber I5. At the top of the cylindrical'valve iii, a valve seat 2| is formed, the seat being masked by a cylindrical masking surface 22 in which a valve 23 is received. The valve is adapted'to seat upon the seat 2| and thus prevent the introduction of air into the air chamber. A lever I 9 may be provided to rock the valve member IS in a proper fashion during the operation of the engine, thus enabling the air chamber to be disconnected from the combustion chamber during the starting operation.

Above the valve member I9 is a chambered head 24 within which the valve'stem 25 of the valve 23 is slidably mounted. The head 24 is provided with a passage 26.which communicates with any suitable source of air pressure as, for example, a pump or accumulator within which air is maintained under a predetermined pressure.

Inasmuch as air is introduced into the air chamber I5 when the valve 23 leaves the masking surface22, a greater amount of air is introduced into the air chamber during the limited time available than in a construction wherein no masking of the valve is provided. By masking the valve, the ordinate 28 (representing zero valve velocity) is advanced to the position indicated at 29. In this fashion, the time indicated between the points 30 and 3| on the curve (representing the time during which the valve 23 establishes communication between the passage 26 and air chamber I5) witnesses a greater average valve area than with an unmasked valve.

Figure 4 represents diagrammatically the cycle of operation of the engine, the inner annulus 32 representing the operation of the inlet valve i1 and the outer annulus 33 the operation of the exhaut valve l8. It will be observed that the inlet valve is closed at 20 degrees on return stroke. The shaded segment 34 represents the time during which the supercharging valve 23 is open 1 only serves as a means for improving the normal operation of the engine; but additionally serves as a means for providing a supercharging action which is independent of the main air supply introduced through the inlet valve. While the invention has been described with specific reference to the accompanying drawings, it is not to be limited save as defined in the appended claim I claim:

1. In combination with '2, Diesel engine head having a combustion chamber formed therein and an air chamber communicating therewith, a source of air under pressure, a valve between the air chamber and combustion chamber, means to adjust the last-named valve, and a masked valve between the air chamber and the source of air, said masked valve moving away from the source of air during its opening movement and being formed to prevent communication between the chamber and source of air during initial motion of the valve toward an open position whereby the amount of air entering the chamber is increased upon initial flow thereof past the valve.

2. In combination with a Diesel engine head having a combustion chamber formed therein and an air chamber communicating therewith, a source of air under pressure, a cylindrical valve in the air chamber, means to rotate the cylindrical valve to control the flow of gases between 'the air and the combustion chambers, a valve port in the cylindrical valve 'coaxlally thereof communicating with the source of air, a valve cooperating with the port, and a cylindrical wall adjacent the port on the side thereof adjacent the air chamber and of substantially the same size as the valve, whereby the last-named valve is masked to prevent communication between the chamber and source of air during initial motion of the valve toward an open position.

3. In combination with a Diesel engine having a cylinder and a head having a combustion chamber formed therein separate from, but communicating with, the cylinder, an air chamber, the head having a port between the air chamber and combustion chamber to afford communication therebetween, adjustable valve means to vary the communication between the air chamber and the combustion chamber, and an air inlet valve and valve seat, said last named valve seat being formed on the said adjustable valve means.

BRUNO LOEFFIER.

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