US3102523A

US3102523A - Spring impulsed engine starter

Info

Publication number: US3102523A
Application number: US154315A
Authority: US
Inventors: Marshall H Frisbie
Original assignee: AC Gilbert Co
Current assignee: AC Gilbert Co
Priority date: 1961-11-22
Filing date: 1961-11-22
Publication date: 1963-09-03
Anticipated expiration: 1980-09-03

Description

S p s, 1963 M. H. FRISBIE 3,102,523

SPRING IMPULSED ENGINE STARTER Filed Nov. 22, 1961 2 Sheets-Sheet 1 ATTORNEY p 3, 1963 M. H. FRISBIE 3,102,523

SPRING IMPULSED ENGINE STARTER Filed Nov. 22, 1961 2 Sheets-Sheet 2 I. I i 34 Milli] INVENTOR 32L .R t WM Hfiie .57 4,} //D ATTORNEY ttes atent Ce 3,ili2,523 Patented Sept. 3, 1963 1 3,102,523 SPRlNG IMPULSED ENGINE STARTER Marshall H. Frisbie, Hamden, Conn., assignor to The A. C. Gilbert Company, New Haven, Conn., 21 corporation of Maryland Filed Nov. 22, 1961, Ser. No. 154,315 Claims. (Cl. 123-179) This invention relates to spring starting devices for internal combustion engines particularly of the very small sizes as used to power model airplanes, boats, toy vehicles and the like.

A form of engine starter for this purpose is disclosed in a copending application, Serial No. 91,032, filed February 28, 1961, in which one end of the starter spring is permanently attached to and involves with a rotor driven by the engine and permits the engine to run, after being started, by the ability of the spring to free itself from temporary anchorage to a stationary part of the engine body.

In the present improvement one end of the starter spring is permanently attached not to the rotor but to a stationary part of the engine body and at its other or outer end is susceptible of winding engagement by the rotor, but in only one rotary direction, i.e. opposite to that in which the engine normally runs, so that the spring can manually be wound in said opposite rotary direction for thereafter deliverin-g starting energy to the engine shaft in normal engine running direction. Reference may be had to the said copending application for fuller explanation of problems peculiar to the provision of a spring starter for miniature engines requiring such starters to be very compact, of light weight, and comprised of a number of parts, as well as low in cost and rugged enough to stand abuse by unskilled users as required of toy products having moving parts.

The provision of an engine starter having improved characteristics in the above respects is a main object of the present improvements.

Related objects are to utilize centrifugal force as a means of sustaining disconnect-ion between the engine rotor and the starter spring while the engine is running under its own power and the starter spring remains stationary.

In miniature engine starters for toy or model airplanes employing a coiled spring as heretofore proposed the impelling engagement by which reverse turns of the engine driven airplane propeller winds the starter spring has been accomplished by first manually stretching the spring coil into engagement with the impeller each time the engine is started, and after the engine starts such engagement is permanently broken until again manually established. Therefore a special object of the present improvements is to provide a starting mechanism wherein a Winding engagement between the engine driven rotor and the starting spring will never permanently be broken but will always enable reverse manual turning of the propeller or engine driven rotor to wind the starter spring without necessitating at each engine starting a separable manipulative operation to enable the rotor to impel the spring in winding direction. Specifically the starter spring in these improvements requires neither stretching nor distortion, nor change in its normal position in order always to be impellable in winding direction by reverse manual turning of the engine driven propeller.

A contributary object is to provide, for manually winding the starter spring, a unidirectional acting catch means always traveling with the engine driven rotor or propeller and capable of automatically engaging the spring and comprising a one-piece rockable pawl pivotally mounted on the rotor of the engine without the use of pivot screws or extraneous parts.

These and other objects of the present improvements are more fully described and set forth in the following description of construction embodying the invention and having reference to the appended drawings wherein:

FIG. 1 is an elevation of the cylinder block of a miniature engine body looking at the end of its projecting power shaft indicated t fragmentarily to carry fixed thereon the hub of a bladed air impeller intended to'be manipulated for starting the engine as shown in FIG. 1 of the aforesaid patent application.

FIG. 2 is a view taken in section on the plane 22 in FIG. 3, looking in the direction of the arrows.

FIG. 3 is an enlarged view of the interior of the spring barrel to which the propeller hub is fixed and is taken in sect-ion on the planes 33 in FIG. 2, looking in the direction of the arrows.

FIG. 4 is a fragmentary view similar to FIG. 3, showing the starter spring in wound condition.

FIG. 5 is a perspective view of the one-piece spring winding catch or pawl detached from the spring barrel.

FIG. 6 shows a structural detail by which the inner end of the starter spring is permanently anchored to a part of the stationary engine body.

FIG. 7 is an exploded view of the parts shown assembled in FIG. 2 drawn in perspective to illustrate the simplicity of assembling and disassembling the improved starter.

FIG. 8 is a view similar to FIG. 4 showing a fragment of the interior of the empty spring barrel of FIG. 5 with spring and catch pawl omitted.

FIG. 9 is a perspective view of the structure shown in FIG. 8.

FIGS. 10 and 11 show a modified shape of the pawl cavity in FIGS. 8 and 9 for presenting to the hooked end of the standing spring complete circular containment when the pawl occupies the cavity.

FIG. 12 is a broken away view of part of the structure in FIG. 4 modified to include constraining member for fixing the radial position of the hooked end of the starter spring and is taken on the planes 1212 in FIG. 13.

FIG. 13 is a View taken in section on the plane 13-13 in FIG. 12 looking in the direction of the arrows.

FIGS. 14 and 15 show a modified construction for fixedly connecting the constraining member of FIGS. 12 and 13 to the hooked end of the starting spring.

In FIG. 1 the body of a miniature internal combustion engine 15 has a crankcase 19 aiiording in its stationary projecting boss 21 a rotary bearing in which the crank shaft or power shaft 20 of the engine is journaled. The stationary bearing boss 21 of the engine body contains in its periphery two anchorage notches 24 each bordered by circumferentially spaced square shoulders 22. Power shaft 20 projects from its bearing in boss 21 to receive fixedly on its toothed portion 30 the correspondingly notched hub 31 of an engine driven rotor including the hollow spring barrel 32. Barrel 32 always turns in unison with shaft 20 and houses between its rim 33 and the bearing boss 21 a spirally coiled, engine starting, band spring 34 having in its inner end portion two shallow loops 35 struck radially inward from the sheet metal of the spring and having a width snugly fitting the space between notch shoulders 22 thus to seat firmly though removably in the notches 24 respectively. Unless intentionally removed the inner end portion of spring 34 remains permanently anchored in fixed relation to the engine body.

The rim 33 of spring barrel 32 bulges externally at one or more points 40 and thereat is recessed internally as at 41 to provide a retentive rotary bearing and cavity 42 in which can be journaled the shank portion 43 of a blade-like pawl 44 best shown in FIG. 5. Pawl 44 is thus free for limited rocking movement in bearing 42 between pawl.

its positions shown in FIGS. 3 and 4, to which positions its rocking movement is limited by the tail spur 45 of the Pawl 44 can be withdrawn from its pivotal hearing only inv a direction aligned with the axis of its shank portion 43 because the diameter of such shank portion is such as to be fittingly encompassed by the borders of cavity 42 for more than half the circumference of the cylindrical contour of the shank portion 43 and blade portion of the pawl 44.

"F1623 shows that the normal position of the hooked outer or free end 36 of the starter spring 34 when the latter is not tensioned is at such radial distance from the axial center of engine shaft 29 as not to exceed the inner diameter of spring barrel 32, although the spring end 36 may be wiped so lightly by the inner surface of the rim 33 of the spring barrel as not to oppose or impede engine running while the spring remains stationary.

The operation of the foregoing described parts is as follows.

The engine driven or load rotor 32 has radial ridges and grooves 50 which permanently unite it rotatively with the hub 51 of a model airplane propeller 52 when the correspondingly ridged and grooved face of propeller hub'51 is pressed axially against rotor 32 by the propeller retaining thrust nut 53 on the screw threaded end of engine shaft 20 in FIGS. 2 and 7. The engine is intended to drive the propeller 52 counterclockwise in the direction of arrow D in FIG. 1, or clockwise in FIGS. 3 and 4. When running speed has been attained in such direction centrifugal force will tend to urge pawls 44 radially outward into occupancy of their cavities 41 so that they clear the hooked end 36 of stationary starter spring 34 while the latterfconstantly self maintains its predetermined position in FIG. 3. When rotor 32 is stationary or is turned only slowly the pawl 41 that is in, or reaches,

top position will by its weight swing radially downward about its pivot shank 43 to the broken line position in FIG. 3 whereupon it will revolve with rotor 32 in a path to engage the hooked spring end 36 and impel the coils of the spring counterclockwise in FIG. 3 (clockwise in FIG. 7) until the spring coil is wound up about the hearing boss 21 into its condition shown in FIG. 4.

This winding of the spring is easily and safely accomplished by the operator by applying his finger to the tip of the propeller blade 52 and swinging it clockwise in FIG. 1. When an increased resistance to the backward turning of the impeller signals that the spring has become wound the operator can safely withdraw his finger from the tip of the impeller, as in the starter of the aforesaid copending application, whereupon spring 34, whose hooked end 36 has remained engaged with pawl 41, flings the impeller and thereby the engine shaft 20 counterclockwise in FIG. 1 (clockwise in FIGS. 3 and 4) while the spring end 36 comes to rest at the end of its unwinding and the play-out of its stored energy. The pawls 41 on rotor 32 are always free to overrun and pass the hooked end of the spring in engine driven direction of rotation. Meanwhile the hooked end of the spring remains stationed in its top position as in FIG. 3 ready again to be engaged by one of the pawls 44 whenever the rotor is turned in reverse or spring winding direction. Thus it will be seen that accidental attempt of the engine to run backward, or contrary to its intended direction of running will be resisted by the hooked end of the starter spring which is always on guard against this eventuality. To help stabilize the position of the hooked end 36 of starter spring 34 at a-fixed radial distance from the axis of engine shaft 20 and in constant radial relation to the location of pawl blade 44, FIGS. 10 and 11 show an internal pad 56 formed integrally with the rim wall 33 of the spring barrel 32 having sufiicient extent axially in the spring barrel to overlap a side margin of the starting spring and to span the circumferential gap in the circular continuity of the inner surface of the barrel rim 33 that appears at the end of the pawl blade 54 in FIG. 3.

To even more positively insure radial fixity of the position of spring end 36 FIGS. 12 to 15 show the addition of a constraining dog-like member 57 having a discal portion 58 loosely rotatable on shaft 20 and an'arm portion 59 having a bent over end portion 60. Portion 60 of the constraining member 57 is made fast to the spring 34 near the latters hooked end 36 by a rivet or eyelet 61 or other fastening means so that the spring 36 can be positively constrained against radial movement with respect to the axis of shaft 20* although the constraining member 57 is free at all times to rotate with or relatively to the engine shaft in either rotary direction for permitting the winding of the starting spring, Athrust washer 62 can intervene between the discai portion 58 of member 57 and the shoulder on shaft 20 to increase the area of axial steadying support for member 57.

In FIGS. 14 and 15 it is shown that in place of the rivet or other fastener 61 the end portion 61' of arm 59 of the constraining member 57 may be lodged fixedly between the surface of the width of the winding spring and a loop 67 struck inward from a central portion thereof. Both the constraining member 57 and the thrust washer 62 will have central holes having a running fit on shaft 26 and provided with radial notches (not shown) like notches 31 in FlG. 7 for permitting these parts to pass the key projections 30 of the shaft when being assembled over the free end of the shaft.

The operation of the parts illustrated in FIGS. 8-15 is like that of the parts in FIGS. 1-7 in that just prior winding the starting spring 34 the pawl blade will swing down by gravity to its position in FIG. 12 to which its radial inward movement is limited by the tail spur 45 so that the catch end of the pawl blade 44 never contacts the rivet 61. Upon manual rotation of propeller 52, spring barrel 32' and engine shaft 20 in unison counterclockwise in FIG. 12, the pawl end engages the hooked end 36 of the starting spring 34- as shown in broken lines and impels it several turns counterclockwise until the spring is fully wound as it appears in FIG. 12. These winding revolutions of the hooked end of the spring are accompanied by equal rotation of the constraining member 57 or 57 in unison with the spring barrel 32'. When the tip of the impeller blade is released by the finger of the operator as aforesaid spring 34 will exert its-[tension by unwinding rapidly in clockwise direction and release the spring barrel 32 to be driven by the thus started internal combustion engine 15 whereupon it will overrun the starting drive of the spring when the hooked end 36 of the spring comes to its natural position of rest shown in FIG. 12 where it is self-stationed when unwound. The hooked end of the spring will remain so stationed ready to be again engaged and wound by the pawl 44 when the engine is next to be started.

The appended claims are directed to and intended to cover all variations and equivalents of the particular shapes and arrangement of parts herein disclosed as fall fairly within a broad interpretation of the terminology used in the claims.

What is claimed is: t

1. In mechanism for starting a miniature internal cornbu stion engine having a load rotor and a stationary engine body, the combination with said rotor and body of, a substantially uniplanar coiled band spring having one end permanently anchored to said body and a hooked 'end constantly located at the same predetermined radial distance from the axis of .said rotor in fixed axial relation to the latter, and a pawl carried on said rotor at least partially in the plane of said band spring in a manner to shift relatively thereto between relatively outer and inner radial positions in which positions said pawl revolves in unison with said rotor respectivelyin arcs of differing radial distance from said rotor axis thereby respectively to clear and impellingly to engage said hooked end of said band spring.

2; In mechanism for starting a miniature internal combustion engine having a load rotor and a stationary engine body, the combination defined in claim 1, together with means to confine the said hooked end of the said spring to its said location in at least one radial direction.

3. In mechanism for starting a miniature internal combustion engine having a load rotor and a stationary engine body, the combination defined in claim 2, in which the said rotor is shaped and disposed relatively to the said hooked end of the said spring to confine the said hooked spring end in a manner to maintain the latter in its said location radially of the said rotor axis.

4. In mechanism for starting a miniature internal combustion engine having a load notor and a stationary engine body, the combination defined in claim 3, in which the said rotor comprises a hollow spring barrel housing the said spring and having a rim presenting a cylindrical inner surface circumferentially external to the said hooked end of said spring and sufficiently close thereto to limit departure of said hooked spring end from its said location in a direction radially outward from the said rotor axis.

'5. In mechanism for starting a miniature internal combustion engine having a load rotor and a stationary engine body, the combination defined in claim 4, in which there is a cavity in the said barrel rim interrupting the said inner cylindrical surface thereof and occupied by the said pawl.

6. In mechanism for starting a miniature internal combustion engine having a load rotor and a stationary engine body, the combination defined in claim 5, in which the said barrel rim contains a pivotal bearing and the said pawl has a shank pivotally journaled in the said bearing for swinging movement toward and away from a position impellingly to engage the said hooked end of the said band spring.

7. In mechanism for starting a miniature internal combusion engine having a load rotor and a stationary engine body, the combination defined in claim 6, in which the said cavity is shaped cooperatively with the said pawl in a manner to limit the said swinging movement thereof.

8. In mechanism for starting a miniature internal combustion engine having a load rotor and a stationary engine body, [the combination defined in claim 7, in which said spring coil is so formed and supported that the said hooked end thereof normally seeks and maintains a position vertically above the said rotor axis, whereby during circular approach to said position the said pawl will be swung downward by gravity into impelling engagement with said hooked end of said spring.

9. In mechanism for starting a miniature internal combustion engine as defined in claim 1, the combination defined in said claim, together with means to prevent departure of the said hooked end of the said band spring radially inward toward the said axis of the said rotor from its said predetermined radial distance from said axis.

10. In mechanism for starting a miniature internal combustion engine as defined in claim 9, the combination defined in said claim, in which the said means to prevent radially inward departure of the said hooked end of the said band spring comprises a rigid arm rotatably loose on the said rotor having a revolvable end fixedly attached to the said band spring near said hooked end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,751,898 De Groat June 26, 1956 2,855,070 McRoskey et a1. Oct. 7, 1958 2,869,682 De Millar Jan. 20, 1959 2,927,660 De Groat Mar. 8, 1960 2,973,754 De Millar Mar. 7, 1961 2,991,779 Barr July 11, 1961

Claims

1. IN MECHANISM FOR STARTING A MINIATURE INTERNAL COMBUSTION ENGINE HAVING A LOAD ROTOR AND A STATIONARY ENGINE BODY, THE COMBINATION WITH SAID ROTOR AND BODY OF, A SUBSTANTIALLY UNIPLANAR COILED BAND SPRING HAVING ONE END PERMANENTLY ANCHORED TO SAID BODY AND A HOOKED END CONSTANTLY LOCATED AT THE SAME PREDETERMINED RADIAL DISTANCE FROM THE AXIS OF SAID ROTOR IN FIXED AXIAL RELATION TO THE LATTER, AND A PAWL CARRIED ON SAID ROTOR AT LEAST PARTIALLY IN THE PLANE OF SAID BAND SPRING IN A MANNER TO SHIFT RELATIVELY THERETO BETWEEN RELATIVELY OUTER AND INNER RADIAL POSITIONS IN WHICH POSITIONS SAID PAWL REVOLVES IN UNISON WITH SAID ROTOR RESPECTIVELY IN ARCS OF DIFFERING RADIAL DISTANCE FROM SAID ROTOR AXIS THEREBY RESPECTIVELY TO CLEAR AND IMPELLINGLY TO ENGAGE SAID HOOKED END OF SAID BAND SPRING.