US3042013A

US3042013A - Fuel supply means for engines

Info

Publication number: US3042013A
Authority: US
Inventors: Eugene L Nelson
Original assignee: Tecumseh Products Co
Current assignee: Tecumseh Products Co
Priority date: 1960-09-12
Filing date: 1960-09-12
Publication date: 1962-07-03
Anticipated expiration: 1979-07-03

Description

July 3, 1962 E. 1.. NELSON 3,042,013 FUEL SUPPLY MEANS FOR ENGINES Filed Sept. 12, 1960 IN V EN TOR. EU6E'NE 4. N51. 50!

A Tree/v5 Y5 States atent Office 3,042,013 Patented July 3, 1962 3,042,013 FUEL SUPPLY MEANS FOR ENGINES Eugene L. Nelson, Cedarburg, Wis., assignor to Tecumseh Products Co., Tecumseh, Mich., a corporation of Michigan Filed Sept. 12, 1960, Ser. No. 55,334 4 Claims. (Cl. 123-73) The present invention relates generally to improvements in crankcase induction of fuel for internal combustion engines, and relates more particularly to improvements in fuel supply valves for controlling the delivery of fuel mixture to the crankcase of engines of the fractional horsepower type.

A primary object of the invention is to provide improved valve means for the introduction of fuel to the crankcases of small horsepower internal combustion engines, whereby the engine will operate at high speed and at maximum volumetric efficiency.

Various types of inspiration or induction devices for admitting successive charges of fuel mixture to one or more cylinders of fractional horsepower type internal combustion engines through the crankcase or crankcases have heretofore been proposed and used extensively. In some of these prior fuel admission devices, the introduction of the fuel mixture into each crankcase is effected as by means of one or two reed type valves formed on a flat apertured plate attached to the fuel inlet line at its opening into the crankcase chamber below the piston. The valves in such a device commonly consist of a flexible reedplate covering the opening and adapted to flex or swing toward the crankcase chamber to direct the charge more orless laterally into the chamber. While such reed plate assemblies have been extensively used, they have neverthelesspossessed certain objections particularly with regard to. efliciency of operation, effective mixing and direction of fuel and relatively slow and restricted delivery thereof to the chamber. Furthermore, the restricted number of inlet apertures and reed type admission valves accommodated by the usual reed plate places eachsuch valve under heavy duty at all times, and failure of one of the reeds to perform its function properly is immediately apparent and exaggerated in the engines operation.

In other instances, fuel induction devices of various shapes and sizes have been proposed in efforts to increase the number of inlet openings and reed valves and to so position the valves as to more effectively deliver the fuel and air mixture to the crankcase chamber in order to improve volumetric efliciency and mixture. One of these valve assemblages is in the general form or'shape of a pyramid in which openings are provided on the four sides, the openings being covered by the usual flexible reeds directed toward the crankcase chamber so as to deliver the fuel and air mixture in a relatively flat stream toward the piston rather than laterally into the crankcase chamher as in prior devices of the flat plate type. While such pyramidal-shaped reed Valve assemblages have resulted in somewhat improved engine performance, the volumetric efficiency and engine operation has still left something to be desired.

It is therefore another object of the present invention to provide a reed-type valve assemblage for fractional horsepower internal combustion engines which obviates the objections and disadvantages of prior devices of this general type.

Another object of this invention is to provide a fuel supply or induction device incorporating a maximum number of reed valves which are compactly nested. and which provide an extensive fuel supply to the crankcase.

A further object of the invention is to provide a reed valve assemblage for use in controlling the supply of fuel mixture to the crankcase of an internal combustion engine in which the reed valves are most efliciently located so as to direct the mixture with maximum efliciency to the crankcase chamber at one end of the piston.

An additional object of the invention is to provide a crankcase fuel injection device for internal combustion engines in which the possibility of valve breakage is minimized by limiting the swinging motion of the individual reed valves in predetermined directions.

Still another object of my present invention is to provide an improved reed type valve device for supplying fuel and air mixture to the crankcase of a two cycle engine which can be readily applied to or removed from the crankcase for inspection without need for removing the closure head for the crank chamber, the reed valve assemblage being located in close proximity to the outside of the crank chamber.

An additional object of the present invention is to provide an improved reed valve structure for supplying fuel mixture to the crank chamber of an internal combustion engine which embodies a plurality of valves assembled on a common fuel supply cage and adapted to introduce large quantities of fuel mixture to the crank case in a most effective manner during each admission cycle.

These and other additional objects and advantages of the invention will become apparent from the following detailed description.

A clear conception of the features constituting the present improvement and of the mode of constructing and of utilizing fuel supply devices embodying the invention may be had by referring to the drawings comprising and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

FIGURE 1 is a part sectional side elevation of a typical internal combustion engine of the fractional horsepower type embodying the present improvement, the section beingtaken through a portion of one of the cylinders, crankcase and fuel supply passage;

FIGURE 2 is a somewhat enlarged exploded perspective view of one of the improved valve assemblages showing one of the reeds and a reed retainer and limit member about to be applied to one side of the cage;

FIGURE 3 is a similarly enlarged side elevation of one of the improved reed valve assemblages; and

FIGURE 4 is a section of the reed valve assemblage taken along the line 44 of FIGURE 3.

While the invention has been shown and described herein as being particularly applicable to one type of fractional horsepower internal combustion engine of the two cycle type, it should be understood that it is not intended to unnecessarily restrict the invention by virtue of such limited embodiment; and it is also understood that certain descriptive terms used herein shall be given the broadest possible interpretation consistent with the disclosure.

Referring to the drawing, the typical fractional horsepower internal combustion engine shown comprises, in general, a fuel induction crankcase 6 forming a housing for a crank 7 carried by the main shaft 8 which is journalled in bearings 9 and projects outwardly away from the opposite sides of the crankcase; a cylinder 1t secured to the crankcase 6 and having therein a piston -11 rcciprocable in the central plane 12 of revolution of the crank, and which is drivingly connected to this crank by a connecting rod 13; and an improved fuel supply device associated with the crankcase 6 remote from the cylinder M for introducing successive charges of fuel mixture into the crankcase and cylinder during normal operation of the engine.

One outwardly projecting portion of the crankshaft S is provided with a fly-wheel l and with engine starting mechanism confined within a housing 16 supported from the crankcase 6, while the opposite outwardly projecting portion of this shaft 8 may be connected to a variety of appliances which are to be driven by the engine. The interior of the crankcase 6is communicable with the interior of the cylinder through a side fuel supply port 17, and the opposite side of this cylinder is provided with an exhaust port 18 communicable with a spent gas receiving and discharge casing 19, while the intermediate end portion of the cylinder is provided with the usual charge ignition spark plug 20.

The improved fuel supply device constituting the gist of the present invention, preferably comprises a hollow polygonal fuel mixture supply cage 22 bounded by external approximately parallel side surfaces 23 and by an external transverse end surface 24- and being provided with outwardly directed fuel passages or

openings

25, 26 terminating respectively at the

surfaces

23, 24; and a flexible reed valve 27 swingable outwardly away from each of said surfaces and coacting with the adjacent openings to control the flow of fuel therethrough into the crankcase 6.

When the device is installed the interior of the cage 22 should be in open communication with a carburetor 28, and the end of this cage adjoining the carburetor may be provided with an external flange 29 adapted to be clamped against a hollow adapter fitting 30 and secured to the crankcase 6 by cap screws 31, as shown in FIGURE 1, it being understood that the adapter fitting may be formed as an integral part of the crankcase. The fuel delivery portion of the cage 22 will then be entirely within the fitting 30 but closely adjacent to the crankcase interior, with the side cage surfaces 23 disposed approximately parallel to the plane 12 and the end surface 24 approximately perpendicular to this plane.

Each of the reed valves 27 is also preferably provided with an arcuate stop 33 secured to the

adjacent cage surfaces

23, 24, and these stops limit the swinging move ment of the reeds and prevent the valves 27 from striking the interior of the fitting 30 or the interior of the crankcase and from swinging into the path of the crank 7. The valves 27 and stops 33 may be formed singly or in pairs as shown in FIGURE 2, and are fastened to the cage 22 by screws 34. Suit-able leakage preventing gaskets may be interposed between the cage flange 29 and the carburetor 28 and fitting 30, and the cap screws 31 permit convenient attachment or removal of the valve cage 22 while the screws 34 permit like application or replacement of the valves 27.

When the improved internal combustion engine has been constructed and assembled as shown in FIGURE 1, and has been applied to the appliance which is to be driven or actuated, the engine may be placed in operation with the aid of the starter confined within the casing -16 in a well known manner, whereupon the reciprocating piston 11 will alternately draw successive charges of fuel mixture from the carburetor 28 past the reed valves 27 into the crankcase 6 and after being compressed within this crankcase the charges enter the cylinder 10 through the inlet port. The piston 11 thereafter compresses the admitted fuel charges which are subsequently ignited by the spark i plug 20 to apply power to the crank 7 through the cylinder outlet port 18 into the exhaust casing 19.

While all of this functioning of the engine is old and well known, it is important to introduce fuel charges of maximum volume to the crankcase 6 during each induction stroke, and such action is effected by providing numerous well distributed but relatively

small inlet openings

25, 26 and valves 27 in the polygonal cage and by directing the entering fuel streams approximately parallel to the direction of reciprocation of the piston 11 in the plane 12 as well as in a direction laterally thereto. This assemblage causes least resistance to the flow of the fuel mixture and therefore insures a full charge during each suction stroke, and while the polygonal cage 22 has been shown as having square transverse cross-section, a greater or lesser number of flat side surfaces 23 formed with openings 25 may be provided without departing from the present invention.

The provision of fiat bounding surfaces is preferred in order to permit tight closing of the reed valves, and the cage 22 should also be of such length that the valves 27 will not swing into the path of the revolving crank 7, while the stops 33 effectively limit the opening movement of these valves. With the introduction of maximum charges of fuel mixture the engine will obviously operate at high speed with maximum volumetric efiiciency, and the invention is advantageously applicable to single and multiple cylinder internal combustion engines.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. For use in an internal combustion engine having a fuel induction crankcase housing a crank operatively connected to and revolvable in the central plane of an engine piston, a substantially cubical fuel mixture supply device having several fuel inlet openings communicable through the side walls thereof with the crankcase, said inlet openings being bounded by adjacent surfaces disposed respectively approximately parallel and perpendicular to said plane, and a reed valve swingable outwardly away from each of said surfaces and coacting with the adjacent opening to control the flow of fuel therethrough into said crankcase.

2. For use in an internal combustion engine having a fuel induction crankcase housing a cnank operatively connected to and revolvable in the central plane of an engine piston, a polygonal fuel mixture supply cage having opposite sides and an end outwardly directed fuel inlet openings communicable with the crankcase and bounded by adjacent surfaces disposed respectively approximately parallel and perpendicular to said plane, and a reed valve swingable outwardly away from each of said surfaces and coacting with the adjacent openings to control the flow of fuel therethrough into said crankcase.

3. For use in an internal combustion engine having a fuel induction crankcase housing a crank operatively connected to and revolvable in the central plane of an engine piston, a polygonal fuel mixture supply cage having fuel inlet openings in four sides and an end thereof all communicable with the crankcase, said side openings being bounded by adjacent surfaces disposed approximately parallel to said plane and said end opening being bounded by an adjacent surface disposed approximately perpendicular to said plane, and a reed valve swingable outwardly away from each of said surfaces and coacting with the adjacent openings to control the flow of fuel therethrou-gh into said crankcase.

4. For use in an internal combustion engine having a fuel induction crankcase housing a crank operatively connected to and revolvable in the central plane of an engine piston, a hollow substantially cubical fuel mixture supply device having fuel inlet openings communicable through the side walls thereof with the crankcase, said inlet openings being bounded by adjacent surfaces disposed approximately parallel and perpendicular to said plane, and a reed valve swingable outwardly away from said surface and coacting with the adjacent opening to control the flow of fuel therethrough into said crank- 5 case, said reed valve each having an arcuate stop plate associated therewith to limit its outward swing.

References Cited in the file of this patent UNITED STATES PATENTS 2,420,056 Seligmann 61328.1. May 6, 1947 10 6 Kiekhaefer May 26, 1953 Kireher et a1. Jan. 24, 1956 'Morgenroth Jan. 29, 1957 Jasper Feb. 26, 1957 Norton Apr. 26, 1960