US3527265A - Speed control device for a model airplane engine - Google Patents

Description

Sept. 8, 1970 L. K. JENNINGS SPEED CONTROL DEVICE FOR A MODEL AIRPLANE ENGINE 2 sheets sheet l Filed Feb. 17, 1969 INVENTOR. LUTHER K. JENNINGS ATTORNEY.

' Se t. 8, 1970 L. K. JENNINGS 3,527,255

SPEED CONTROL DEVICE FOR A MODEL AIRPLANE ENGINE 2 Shec ts-Shee t 2 Filed Feb. 1'7, 1969 INVENTOR.

ATTORNEY.

United States Patent 3,527,265 SPEED CONTROL DEVICE FOR A MODEL AIRPLANE ENGINE Luther K. Jennings, 2712 Summerfield Road, Winter Park, Fla. 32789 Filed Feb. 17, 1969, Ser. No. 799,661 Int. Cl. F02d 9/06, 33/ 00; F02m 25/06 US. Cl. l2398 Claims ABSTRACT OF THE DISCLOSURE The carburetor air inlet of a model airplane engine is provided with relatively shiftable inner and outer sleeves for selectively effecting communication of the air inlet with the ambient air and the engine exhaust.

BACKGROUND OF THE INVENTION While speed control devices for internal combustion engines are not new, and have assumed many forms, there has not been provided in the past any satisfactory speed control mechanism for relatively small internal combustion engines of the type employed in model airplanes. Hence, it has been customary in the past to operate model airplane engines at full throttle without varying the engine speed.

SUMMARY OF THE INVENTION Accordingly, it is an important object of the present invention to provide a speed control device for use with model airplane engines which can accurately vary the en gine speed between full throttle and an idle speed.

It is a further object of the present invention to provide a speed control apparatus of the type described which is extremely simple in construction, requiring a minimum of parts, and conveniently operable by the user.

It is still a further object of the present invention to provide a speed control device for model airplane engines, having the advantageous characteristics mentioned in the preceding paragraphs, which is staunch and durable in construction for reliable operation throughout a long useful life, can be readily incorporated with conventional model airplane engines, either as original equipment or as an attachment, and which can be economically manufactured for sale at a reasonable price.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view showing a model airplane engine employed in conjunctionwith a speed control device in accordance with the teachings of the present invention.

FIG. 2 is a top plan view of the assembly of FIG. 1.

FIG. 3 is an exploded perspective view showing the speed control mechanism of the present invention apart from the remainder of the engine.

FIG. 4 is a partial horizontal sectional view taken generally along the line 44 of FIG. 1, illustrating a full speed operational position of the speed control mechanlsm.

FIG. 5 is a horizontal sectional view similar to FIG. 4, but illustrating an idle speed position of the control mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, and specifically to FIGS. 1 and 2 thereof, a model airplane engine is there generally designated 10, which may be a single cylinder engine including a cylinder block 11 provided on its upper end with a cylinder head 12, and on its lower end with a crank case 13. A cylinder exhaust extends laterally from one side of the cylinder block, as at 15, and a drive shaft 16 extends from one end of the crank case 13. The engine block 11 may be provided with lateral wings 17 for mounting the engine on a suitable bed.

Upstanding from the crank case 13 is a carburetor generally designated 20. The carburetor may include a generally cylindrical body 21 having its lower end connected for fluid communication with the interior of the cylinder block 11 in any suitable manner. The upper end of the carburetor body 21, as at 22, may provide an air inlet for the carburetor. A fuel conduit 23 may be connected at one end to a fuel supply (not shown), and connected at its other end by a fitting 24, to the interior of the carburetor body 21 for delivering fuel thereto. A needle valve 25 may be mounted in the carburetor body 21 opposite the fuel inlet fitting 24 for varying the opening thereof. That is, the needle valve 25 may be rotated by its handle 26 in opposite directions to regulate the fuel flow to the carburetor. To maintain the needle valve 25 at a selected position of its rotative movement, as for passing a desired rate of fuel to the carburetor, the needle valve may be provided with a toothed or serrated wheel 27 for rotation with the needle valve, and one or more resilient or spring fingers 28 fixed at one end to the carburetor body and in frictional bearing engagement with the wheel 27. In this manner, the needle valve 25 is effectively held at any selected position of adjustment even under severe conditions of vibration and other motion. Of course, the needle valve 25 may serve to regulate the fuel supply and the resultant engine speed, but this mode of speed regulation is extremely limited and inconvenient.

Mounted on the body 21 of carburetor 20, particularly on the air inlet end 22 of the carburetor body, is the speed control device of the present invention, there generally designated 30. As best seen in FIG. 3, the speed control mechanism includes an inner sleeve 31 defined by an open ended generally cylindrical tube, which may have its lower end 32 fixedly secured to the upper end of the carburetor body 21 for fluid communication with the air inlet of the carburetor. Formed in the inner sleeve or tube 31 is an elongate opening or slot 33. It will be observed that the elongate opening or slot 33 extends partially circumferentially about the tube 31, approximately one-half the circumference thereof, and is spaced between the lower tube end 32 and the upper tube end 34. As best seen in FIGS. 4 and 5, the inner sleeve or tube 31 is fixedly secured in end-to-end aligned relation with the upper or air inlet end of the carburetor body 21, the elongate opening or slot 33 facing obliquely forwardly and laterally to the right, as shown in the illustrated embodiment.

Rotatably circumposed about the inner sleeve or tube 31, in snug sliding relation therewith, is an outer sleeve or tube 35. That is, the outer sleeve 35 is defined by an open ended tube rotatably surrounding the inner sleeve or tube 31 and approximately longitudinally coextensive therewith. Formed in the outer sleeve or tube 35 is a through hole 36, which is spaced intermediate the lower and upper tube ends 37 and 38 so as to lie in facing relation with the inner sleeve opening or slot 33. That is, the outer sleeve or tube 35 is rotatable coaxially with the inner sleeve or tube 31; and, the generally circular outer sleeve opening ir hole 36 is movable with the outer sleeve between a forward location, as in FIG. 4, in alignment or registry with a forward end region of the slot 33, and a sideward location in alignment or registry with a sidewardly facing region of the slot 33, as in FIG. 5. If desired, suita'ble stop means may be provided to limit rotation of the outer sleeve 31 between the extreme positions shown in FIGS. 4 and 5. Of course, the outer sleeve 31 may be placed in any selected position of rotation intermediate the extreme illustrated positions, as desired.

The upper ends of the inner and outer sleeve 31 and 35 are effectively closed by suitable closure means, such as a plug 40 engageable in the upper end of the inner sleeve. The plug or closure means 40 thus closes the upper ends of the coaxial sleeves 31 and 35, and, by its up wardly enlarged configuration effectively retains the outer sleeve in position on the inner sleeve. An operating member or arm 41 may be fixed to the outer sleeve 35, extending generally tangentially therefrom, for remote actuation of the outer sleeve to selectively position the latter in any desired relation with respect to the inner sleeve. Suitable remote actuating means may be connected to the operating arm 41, if desired.

A by-pass conduit is generally designated 43, and includes an intermediate tubular portion 44 having one side open, as at 45 for fixed securement in communicating relation with the cylinder exhaust 15. Extending from one end of the intermediate by-pass conduit portion 44 is a conduit portion 46 which terminates in an open end 47 proximate to and facing toward the outer sleeve 35. Further, the by-pass conduit end 47 is advantageously configured for conforming facing relation with the cylindrical exterior surface of sleeve 35 and located in alignment with the laterally facing portion of slot 33. Extending from the other end of the intermediate 'by-pass conduit portion 44 is an outlet portion or tailpipe 4 8. Thus, the engine exhaust communicates through the side opening 45 of the by-pass conduit 43 both with the conduit 46 extending to the exterior of outer sleeve 35, and through the tailpipe portion 48 with the ambient atmosphere.

It will now be appreciated that the conformably configured end 47 of by-pass conduit 43 is in conforming facing relation with the exterior surface of outer sleeve 35, and that the latter is rotatable to selectively place the hole or aperture 36 in aligned registry with the conduit portion 44, as in FIG. 5, and out of alignment therewith, as in FIG. 4. The outer sleeve 35 is thus interposed between the inner sleeve 31 and the conduit end 47, and may be slidable therebetween.

In the condition of adjustment of outer sleeve 35 as shown in FIG. 4, it will be apparent that the hole 36 of the outer sleeve communicates between the forward region of slot 33 of inner sleeve 31 and the exterior atmosphere or fresh air. Thus, a maximum quantity of air and oxygen may be drawn into the inner sleeve 31 and to the carburetor air inlet 22 for high entrance speed. In this condition, the by-pass conduit 43 is closed by the outer sleeve 35 across conduit end 47, so that exhaust gases proceed as indicated by the arrows 50, all exiting through the tailpipe 48.

In the condition of adjustment of outer sleeve 35 as shown in FIG. 5, the hole or aperture 36 is in alignment or registry with the by-pass conduit end 47, so that the by-pass conduit communicates through the hole 36 and slot 33 with the interior of inner sleeve 31 to the air inlet of the carburetor 20. In this condition a minimum of fresh air and oxygen may be drawn into the air inlet of the carburetor, although there may be successful operation with appreciable leakage. However, a substantial proportion of exhaust gases from exhaust outlet 15 pass in the direction of arrows 51 through by-pass conduit portion 46 and enter through hole 35 and slot 33 to the interior of inner sleeve 31, for passage to the carburetor 20. As this mixture of gases to the carburetor contains less oxygen, the engine speed is considerably reduced, as to an idling speed. Of course, intermediate positions of the outer sleeve 35, as with the hole 36 partially communicating with both the by-pass conduit portion 46 and the fresh or ambient air may be employed to obtain speeds intermediate those of idling and full throttle.

From the foregoing, it is seen that the present invention provides a speed control device for a model airplane engine which fully accomplishes its intended objects and is well adapted to meet practical conditions of manufacture and use.

Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention.

What is claimed is:

1. A speed control device for a model "airplane engine having a cylinder exhaust and carburetor air inlet, said device comprising an inner sleeve having one end connected in fluid communication with said air inlet, said inner sleeve having a through slot communicating between the interior and exterior of said inner sleeve, an outer sleeve slidably engaged over said inner sleeve in covering relation with said slot, said outer sleeve having a through hole movable with said outer sleeve and communicating through said slot at spaced locations thereof upon movement of said outer sleeve, and a by-pass conduit communicating between said exhaust and the exterior of said outer sleeve adjacent to one of said locations, whereby outer sleeve movement to position said hole at said one location eflects communication of said exhaust with said air inlet for reducing engine speed and outer sleeve movement to position said hole at another location effects communication of fresh air with said air inlet for increased engine speed.

2. A speed control device according to claim 1, said inner sleeve comprising a cylindrical tube, said slot being partially circumferential in extent, and outer sleeve comprising a cylindrical tube rotatably circumposed about said inner sleeve tube, said hole being located in said outer sleeve tube for rotative movement therewith between said one location communicating with said by-pass conduit and said other location communicating with ambient air.

3. A speed control device according to claim 2, in combination with closure means closing said inner and outer sleeve tubes remote from said air inlet.

4. A speed control device according to claim 3, said bypass conduit having one end configured for conformance with said outer sleeve tube.

5. A speed control device according to claim 3, in combination with an operating arm connected to said outer sleeve tube for selective positioning of the latter.

References Cited UNITED STATES PATENTS 1,380,173 5/1921 Abel 123-1l9 1,552,819 9/1925 Brush et al. 123119 2,627,851 2/1953 Cushman 123 107 X R 2,030,508 2/ 1936 Falconer 123-119 2,806,458 9/1957 Mett et a1 12398 XR 2,921,568 1/1960 Mett et a1 123-107 2,940,434- 6/1960 Stanzel 123-107 WENDELL E. BURNS, Primary Examiner US. Cl. XJR. 123107, 119

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