US3094109A - Reversal inhibiting engine starter with centrifugal brake - Google Patents

Description

June 18, 1963 w. EFFINGER, JR

REVERSAL INHIBITING ENGINE STARTER WITH CENTRIFUGAL BRAKE 2 Sheets-Sheet 1 Filed Feb. 23', 1961 INVENTOR w sssggm efim ATTORNEY June 18, 1963 w. L. EFFINGER, JR 3,094,109

REVERSAL INHIBITING ENGINE STARTER WITH CENTRIFUGAL BRAKE Filed Feb. 23, 1961 2 Sheets-Sheet 2 INVENTOR 58. 8% e4, 5 2. BY

Patented June 18, 1963 3,094,109 REVERSAL INHIBITING ENGINE STARTER WITH CENTRIFUGAL BRAKE William L. Elfinger, Jr., Harnden, Comm, assignor to The A. C. Gilbert Company, New Haven, Conn, a corporation of Maryland Filed Feb. 23, 1961, Ser. No. 91,032 12 Claims. (Cl. 123-179) This invention relates to starting devices for internal combustion engines particularly of the very small sizes used to drive model airplanes, boats, toy vehicles and the like.

It has been proposed to start such engines by manually tensioning a spiral spring and then releasing it to whirl the engine shaft in running direction. The spring has been so tensioned by a few spring winding manually impelled turns of the engine-driven rotor in backward direction opposite to the intended direction of engine running. In the case of a toy airplane engine, the rotor is a driven propeller fixed to the engine shaft and serving as a crank handle by which to wind up the spring for engine starting action when manually released. Obviously when once started and engine driven the propeller shaft must be able to continue its engine driven rotation in the proper direction free of hindrance by the spring.

Many engines of the type here most concerned can fire as readily in one direction of running as in the other, depending on minute variations in the time and speed of the crankshaft with respect to occurrence of the explosion when the piston reaches and passes top center in the stroke of the crankshaft.

Thus an engine of this type after starting to run in one direction can, upon sufficient reduction of speed incurred by increase in load, or failure of fuel supply, automatically reverse its direction of running for lack of sufficient momentum in the moving parts to carry the piston fully over top center at the time the engine fires.

It has been proposed to accomplish such automatic freeing of the engine shaft from the driving action of the spring by permanently anchoring one end of the starter spring to the engine body and permitting the opposite end of the spring to uncouple automatically from its rotor driving connection. Hence, prior to the present improvement, it has been proposed that the starter spring remain stationary with the engine body after having functioned to start the engine.

In this previous way of starting engines there has been no safeguard against firing of the engine in a way that can run the engine in the wrong direction. Frequent need of corrective stopping and restarting of the engine has been taken for granted.

An object of this invention is to provide a spring action starting device of required simplicity, low cost, durability, and positiveness of action which positively restricts running of the engine to a single intended forward direction of rotation at all times.

A related object is similarly to inhibit running of the engine in reverse or backward direction even if the engine attempts to reverse its direction of running at any time after having been started initially in the forward or right direction.

Another object is to enable the starter spring to rotate bodily in unison with the engine driven rotor instead of remaining stationary with the engine body, so that the weight of the revolving starter parts may serve as a fly-wheel on the engine shaft with benefit to the smoothness of running of the engine.

Another object is to interpose improved brake means between the starter spring and the engine body as part of connections operatively couplingthe engine driven rotor to the engine body.

Another object is to provide such brake means arranged to perform its automatic coupling and uncoupling action by the action of centrifugal force.

Another object is to enable the engine driven rotor to become uncoupled from the engine body before it has completely dissipated the energy stored therein by its manual prewinding for starting the engine.

The foregoing and other objects of the invention will become apparent from the following description of successful embodiments of the improvements having reference to the appended drawings wherein:

FIG. 1 is a perspective external view of a miniature single cylinder internal combustion engine rigged to drive a toy airplane propeller and incorporating starting devices embodying the invention.

FIG. 2 is a somewhat similar view of the same engine with the propeller and starting devices removed to expose the crankshaft of the engine.

FIG. 3 is a perspective view of the starting devices removed from the propeller and the engine parts of FIGS. 1 and 2.

FIG. 4 is a fragmentary enlarged side elevation of the engine, propeller and starting devices in FIG. 1 showing the starting device and propeller hub in section on angularly related radial planes 4-4 in FIG. 5.

FIG. 5 is a view taken in section on the plane 5-5 in FIG. 4 looking in the direction of the arrows.

FIG. 6 is a view taken in section on the plane 6-6 in FIG. 4 looking in the direction of the arrows.

FIG. 7 is a view similar to FIG. 5 showing on an enlarged scale a modified embodiment of the invention.

FIG. 8 is a view taken in section on the plane 8-8 in FIG. 7 looking in the direction of the arrows.

FIG. 9 shows a modified construction of the centrifugal clutch of FIGS. 7 and 8.

FIG. 1' 0 shows a further modified construction of centrlifugal clutch taken partially in section on a diametral p ane.

FIG. 11 is a view taken in section on the plane 11--11 in FIG. 10 looking in the direction of the arrows.

FIG. 1 represents the body 12 of a typical miniature single cylinder combustion engine equipped at each side with a lug 13 containing holes 14 for mounting the engine removably on the framework of a toy airplane (not shown) or other small craft, boat or vehicle to be powered by the engine. Engine body 12 conventionally includes a power cylinder 15, an air intake 16, a fuel intake 17, exhaust cooling fins 18 and the crankcase 19.

The crankcase portion of the engine body includes bearing structure 2 1 in which the crank shaft 20 is journalled. Such structure comprises a cylindrical boss containing an external notch 24 providing a stationary detent shoulder 22. The crankshaft projects from its bearing to receive fixedly on its knurled portion 30 the 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 stationary boss 21 of the engine body a spirally coiled engine starting band spring 34 having its outer end permanently secured to the drum ring 33 by a rivet 37 and carrying fixed to its inner end by rivets 36 a weighty catch or latch 35. Spring 34 is so resiliently conditioned that it normally biases the latch 35 radially inward into wiping contact with boss 21 so that the latch automatically seeks and becomes seated in the stationary notch 24 in hooked engagement with a keeper for-med by the detent shoulder 22.

Latch 35 has sufiicient weight to be sensitive to centrifugal force and thereby can be flung radially outward away from hearing boss 21 and clear of the notch shoulder 22 by rapid speed of rotation of barrel 32 with engine shaft 20' when such force is great enough to overcome. the. natural bias in spring 34 and cause flexure of the. spring in an unwinding direction. Thus the engagement and disengagement of catch or latch 35 with notch shoulder 22 of the keeper functions automatically in response to variation in speed of the engine shaft in such manner that when stationary, or revolving at relatively slow speed, the turning of shaft 20 counterclockwise in FIG. (clockwise in FIGS. 1 and 6) will act to wind up spring 34 to a limited extent and store tension therein which subsequently can operate automatically to whirl shaft 20 in counterclockwise or forward running direction in FIGS. 1 and 6 (clockwise in FIG. 5 This will whirl the crankshaft so rapidly past top center position of the piston that starting of the engine ordinarily will take place in the intended forward direction, If it does not, and if; faulty firing causes accidental starting of the engine in reverse direction, the catch 35 immediately reengages with notch shoulder 22 and checks turning of the shaft in such wrong direction whereupon the momentum of the rotor parts such as 32 turning in wrong direction will automatically repeat a winding up of the spring so that when the back firing force of the engine is spent the spring will again automatically function to whirl the shaft in forward or engine running direction and thereby restart the engine in proper direction without manual attention. Such automatic checking of backward rotation followed by engine restarting automatic drive of the shaft in forward direction will occur at any time when temporary reduction of speed results in accidental back-firing of the engine while it is running.

In the drawings the load to be rotated by crankshaft 20 is represented by the propeller 49 of a toy or model aircraft whose hub 41 is fixedly interlocked with spring barrel 32 by the mutual engagement of radially disposed and mating ridges and grooves 42 on the propeller hub and 43 on the mating face of the barrel hub 31. The propeller is removably secured on the crankshaft 20 by a retaining nut 44 and slip washer 45.

In starting an engine by use of the invention when embodied in the form of mechanism shown in FIGS. 1 to 6, inclusive, the engine is assumed first to be, at rest with the catch 35 biased against the stationary bearing boss 21, ready automatically to enter the notch 24 in releasable hooking relation to notch shoulder 22. A finger of the operators hand is applied to impeller 40 in a manner to swing it a few turns clockwise as viewed in FIG. 1. The catch 35 will seek and enter the notch 24 and be held stationary by notch shoulder 22 while a subsequent few turns of the spring barrel 32 clockwise in FIG. -1 prewind or store up engine starting tension in the spring. The operators finger tip, can then be withdrawn abruptly and safely from the extreme end of the propeller blade. Spring 34 will immediately deliver its stored up energy to the rotor 32 by rapid unwinding fiexure which whirls spring barrel 33 a few turns clockwise. Engine shaft 20 thereby becomes effectively cranked in engine running direction causing the engine to fire and take over the drive of the shaft, the spring, spring barrel and the propeller, all in unison.

Thereupon these engine driven rotor parts pick up and run ahead of the initial rotor driving action of the starter spring. Catch 35 will be flung by centrifugal force radially outward away from its anchored retention by keeper 22 as permitted by flexure of the starter spring 34 and Will be maintained thus freed from engagement with bearing boss 21 so long as the engine continues to impart rapid; rotation to the spring as the latter travels in unison with the engine driven rotor.

In the absence of the action of centrifugal force, spring 34 could not be relied on to insure starting or automatic restarting of the engine. in correct or forward direction in the event of backward firing of the engine. However the action of such centrifugal force is not necessary for freeing catch 35 from notch shoulder 22 merely l :r i 4 to permit engine drive of the propeller in forward direction, namely counterclockwise in FIGS. 1 and 6 (clockwise in FIG. 5) because the catch can always ride freely out of notch 24 in that direction.

The above described characteristics of a starter operating on the principles of this invention differ from comparable starters, as heretofore constructed and functioning, in that the starter spring in previously known starters has been disenabled to operatively connect the engine driven rotor and the engine body by a break in transmission of spring power to the engine driven rotor instead of by breaking the retentive anchorage of the spring to the stationary engine body, and the disenabling of the starter spring can occur before it has become completely unwound or deenergized. The benefits arising from the present improvements are derived in part from ability of the starter spring to become thus automatically freed by centrifugal force from anchorage to the engine body even while the spring remains partially energized.

In the modified construction shown in FIGS. 7 and 8, the radially outermost end of the starter spring 34 is permanently secured by a rivet 37 to the rim 33 of an engine driven rotor which includes the spring barrel 32 as in FIGS. 1 to 6. But in place of a catch like 35 floating with the radially innermost end of spring 34 the inner spring end is permanently secured to the rim 49 of a cup shaped brake ring 50 by a rivet 51. This ring has a loose running fit in a circumferential bearing groove 52 on the external cylindrical surface of the boss 21 of the engine body 19 thus deriving axial thrust from the side shoulders of such groove. Within the annular space intermediate the rim 49 of the brake ring 56 and the bearing boss 21' there are pivotally carried two or more detent pawls 53 independently swingable on pivot studs 54 fixed in the web wall 55 of brake ring 50, preferably at diametrically opposite sides of the ring respectively.

Each pawl 53 is individually biased by a short leaf spring 56 fixed thereon and bearing outward against the inner surface of ring rim 49 in a manner constantly to urge the hook head 57 of the pawl toward the stationary bearing boss 21' and into releasable latching engagement with either of the shoulders 22 of notches 24 in the stationary bearing boss. Each pawl head 57 is weighted by an insert 58 of substance such as lead or steel having heavier specific gravity than the material of the pawl which may be nylon. Such weighting will aid in enabling centrifugal force exerted on the pawl head to overcome the resilient resistance of pawl springs 56 and swing the pawl counterclockwise in FIG. 7 and out of detentive engagement with notch shoulder 22 and maintain such disengagement as long as brake ring 50 is rotated by engine drive with sufiicient angular speed to generate the required centrifugal force.

The pawls 53 are sometimes referred to herein as the latch elements of a centrifugal brake. A simplified form of such pawls is shown at 53' in FIG. 9 wherein the pawl thrusts against, instead of pulling on, the keeper shoulder 63 of notch 62 in the bearing boss 61 of the engine body. This keeper shoulder is inclined at a slightly obtuse angle rather than an acute angle with respect to tangency to its circle of rotation.

In FIG. 9 one of the pawls 53' is shown drivingly engaged with its keeper shoulder 63 while the other is shown disengaged therefrom merely to illustrate the engaged and disengaged positions between which the pawl can swing. It will be observed that the eccentric portion of the pawl body that engages the keeper shoulder 63 is more massive than in the pawls 53 of FIG. 7 whereby to be self reactive to gravity and centrifugal force so that pawls 53 will fall into engagement with notches 62, and automatically withdraw therefrom, without need of pawl biasing springs such as 56 in FIG. 7. Pawls such as 53' are preferably made very loosely swingable about their pivot studs 54.

FIGS. 10 and 11 show a still further modified construction wherein ring 68 drives brake ring 67 and together therewith and can be anchored against rotation at respectively dififerent speeds as well as in predetermined direction, by a claw tooth or teeth 66 projecting from and forming part of a brake ring 67. This provides a claw type of centrifugal brake in which ring 67 is joined by leaf springs 73 in spaced and axially slidable relation to clutch ring 68, which latter is arranged and connected to function in relation to the other parts of the starter like part 50 in FIGS. 7 to 9 inclusive.

In FIGS. 10 and 11 an axially facing shoulder 69 on bearing boss 70 is provided with as many notches 71 having keeper shoulders 72 as there are claw teeth 66 on brake ring 67, all being equally spaced circumferentially. Brake ring 67 is joined to ring 68 by two or more pairs of the aforesaid radially extending bowed spring leaf arms 73 which at their radially outermost ends are fixed together and fixedly carry weights 74. When brake ring 67 is driven to rapid rotation through spring arms 73 by ring 67 the radially outward pull of weights 74 on the bowed spring arms 73 in response to centrifugal force tend to straighten the spring arms with consequent drawing of brake ring 67 toward the left in FIG. 10'. Thereupon all of the claw teeth 66 become disengaged from the stationary bearing boss notches 71 and free brake ring 67 from anchorage coupling to the body of the engine. In the absence of sufficiently high speed of rotation of ring 68 the resilience in spring arms 73 restores the brake ring 67 into anchored engagement with the stationary bearing boss 7 0 of the engine body.

Certain advantages arise from maintaining the starter spring permanently connected to the engine driven rotor so as always to travel bodily in unison therewith whether the brake is a centrifugal clutch or simply a one-way holding brake permitting the engine driven rotor to outrun the initial driving action of the starter spring in one direction. These and all other variations of the exact kind and arrangements of parts herein proposed are intended to be covered by the appended claims if coming within a broad interpretation of their terminology.

What is claimed is:

l. The combination with the driven rotor and stationary body of an internal combustion engine of, connections for elastically coupling said rotor to said engine body comprising at least in part, engine starting resilient means permanently attached to said rotor to travel in unison therewith, and positively self latching brake means operatively interposed between said resilient means and said engine body operative automatically to couple and uncouple said rotor and engine body in respectively opposite directions of rotation of the former relative to the latter.

2. The combination with the driven rotor and stationary body of an internal combustion engine of, connections for elastically coupling said rotor to said engine body comprising at least in part, engine starting resilient means permanently attached to said rotor to travel in unison therewith, and self latching brake means including a keeper in fixed relation to said engine body and a catch cooperative with said keeper mounted to revolve with said rotor and shiftable relatively thereto ina direction automatically to couple and uncouple said rotor and engine body responsively respectively to changes in centrifugal force at diiferent angular speeds of rotation of said rotor relative to said engine body.

3. The combination defined in claim 1, in which the said resilient means is a coiled starter spring and the said brake means comprises a stationary keeper on the said engine body cooperative with a latch carried on an end 6 of said spring in position to be permitted by flexure of said spring to engage retentively with and to disengage from said keeper. 1

4. The combination defined in claim 3, in which the said latch is weighted in a manner to be caused to escape automatically from retentive engagement with the said keeper by centrifugal force exerted on the said starter spring and generated by relatively high angular speeds of said rotor and said spring in unison.

5. The combination defined in claim 4, in which the said starter spring is statically conditioned by its own resilience to bias the said latch in direction to seek and automatically resume retentive engagement with the said keeper when relieved of the said centrifugal force after being disengaged thereby from said keeper.

6. The combination defined in claim 1, in which the said brake means comprises, a stationary keeper on the engine body, a brake ring drivably connected to the said engine starting resilient means, a rotor bearing confining said brake ring to circular movement coaxially of the said engine driven rotor, and at least one latch element driven by the said brake ring in shiftable relation thereto in a circular path enabling said element by shifting position relatively to said brake ring to engage retentively with and disengage from the said keeper on respectively different occasions.

7. The combination defined in claim 6, in which the said latch element is a detent pawl pivotally mounted on the said brake ring in swingable relation thereto.

8. The combination defined in claim 7, in which the said detent pawl is shaped and disposed in respect to its mounting on the said brake ring to be urged to shift relatively thereto in a direction to disengage automatically from the said keeper responsively to centrifugal force generated by rotation of said brake ring.

9. The combination defined in claim 8, together with a spring reactive between the said brake ring and the said detent pawl urging the latter in direction to engage detentively with the said keeper.

10. The combination defined in claim 6, in which the said latch element is shiftable in relation to the said brake ring in a direction parallel with the axis of rotation of the latter.

11. The combination defined in claim 10, together with a governor spring connecting the said latch element to the said brake ring in a manner to bias said element toward the said keeper, and a weight carried by said governor spring in a manner to flex said governor spring in direction to disengage said latch element from retentive engagement with said keeper in response to centrifugal force generated by rotation of said brake ring.

12. The combination defined in claim 1, in which the said direction of rotation in which the said self latching brake means is operative automatically to uncouple the said rotor and the said engine body is the same rotary direction as that in which the engine is started to run by the power of the said resilient means, whereby said rotor must be turned in the opposite direction to tension said resilient means to deliver said power.

References Cited in the file of this patent UNITED STATES PATENTS 2,855,070 McRoskey et a1. Oct. 7, 1958 2,869,682 De Millar Jan. 20, 1959 2,876,866 Barr Mar. 10, 1959* 2,927,660 De Groat Mar. 8, 1960

Claims (1)

1. 2. THE COMBINATION WITH THE DRIVEN ROTOR AND STATIONARY BODY OF AN INTERNAL COMBUSTION ENGINE OF, CONNECTIONS FOR ELASTICALLY COUPLING SAID ROTOR TO SAID ENGINE BODY COMPRISING AT LEAST IN PART, ENGINE STARTING RESILIENT MEANS PERMANENTLY ATTACHED TO SAID ROTOR TO TRAVEL IN UNISON THEREWITH, AND SELF LATCHING BRAKE MEANS INCLUDING A KEEPER IN FIXED RELATION TO SAID ENGINE BODY AND A CATCH COOPERATIVE WITH SAID KEEPER MOUNTED TO REVOLVE WITH SAID ROTOR AND SHIFTABLE RELATIVELY THERETO IN A DIRECTION AUTOMATICALLY TO COUPLE AND UNCOUPLE SAID ROTOR AND ENGINE BODY RESPONSIVELY RESPECTIVELY TO CHANGES IN CENTRIFUGAL FORCE AT DIFFERENT ANGULAR SPEEDS OF ROTATION OF SAID ROTOR RELATIVE TO SAID ENGINE BODY.

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