US2789551A - Pull starter guide means - Google Patents

Description

April 23, 1957 w. E. ARMSTRONG 27,789,551

PULL STARTER GUIDE. MEANS Filed Oct. 15r 1954 3 Sheets-Sheet 2 F`\ C-a. 4 F C1- 5 JNVENTOR.

April 23, 1957 Filed oct. 15, 1954 W. E. ARMSTRONG PULL STARTER GUIDE MEANS 3 sheets-sheet :s

IN VEN TOR.

Que/2M 9 aux.

PULL STARTER Goins MEANS Application October 13, 195,4,Serial No. 462,033 a claims. (c1. 12s-18s) The invention relates to` manually operated devices called pull starters for rotating` the crankshaft of an internal combustion engine `through self-rewinding wrapped cordY means including releasable clutch means engageable with a part attached to the crankshaft-of the engine, which means is released by the motion of the crankshaft when the enginestarts. i t

ln starters of the type abovedescribe'd, the pull cord when actuated usually runs tangentially of and in the same plane as the groove of the wheel in which the cord is mounted. Where starters are used on some lawn mower drive engines and other mobile equipment, it has been found that the usual straight pullon the pull cord cannot be readily ellec'ted because of other parts of the equipment or'the disposition of the equipment at the time of starting,

and the `object of the present invention is to overcome this difficulty by providing a pulley guide means for the pull cord which enables the cord to be pulled out from its reel at an angle to the horizontal axis of'the wheel.` With this arrangement, when the pull starter is mounted on the top of the equipment, the pull cord may be manipulated from the top of the apparatus instead of from its side, making starting much easier than has heretofore been the case.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a side view in elevation of a starter embodying the invention shown mounted on an internal combustion engine, indicated diagrammatically;

Fig. 2 is a enlarged transverse sectional View through the starter shown in Fig. l with a part of the engine shown in full;

Fig. 3 is an enlarged front view in elevation with parts broken away and in section of the starter shown in Fig. l;

Fig, 4 is a detailed front view in section of the outwardly acting clutch parts of the starter shown in Fig. 1, the parts being in the position occupied when the starter is idle; f

Fig. 5 is a detailed front view in section similar to Fig. 4 showing the clutch parts in the position they assume after the starter cord has been pulled slightly causing initial contact of the clutch parts;

Fig. 6 is a detailed front view in section similar to Figs. 4 and 5 showing the clutch parts after the starter cord has been pulled far enough to bring the clutch into full engagement;

Fig. 7 is a detailed front elevation view looking toward the left in Fig. l, showing the cord guide means in position, for example, right hand rotation of the engine crankshaft;

Fig. 8 is a view similar to Fig. l7 showing the cord guide means in position for left hand rotation of the engine crankshaft;

Fig. 9 is a plan view of the parts, arranged as indicated in Fig. 7.

While the cord guide means hereinafter described may be used on pull starters whose specicstarter parts may nited States PatentfO 2,789,551 kliatented- Apr. 23, 1957 ice differ, I have shownby way of example one form of starter in connection with which the invention may be incorporated.

In the drawings, an air-cooled engine 1 is provided with a flywheel housing 2 in which a llywheel fan, not shown, provides cooling air drawn through a central opening 3 therein. The starter, shown in the drawings, is adapted to be mounted in front 'of the opening 3, and for this purpose has an'open sided flanged mounting ring 5 secured to housing 2 by means of cap screws 6 with an annular screen 4 secured to the open side portion of said ring.

A cover 7 for the driving parts-of the starter is secured by screws 8 to mounting `bosses on'thering 5. Cover 7 provides a rigid support fora centrally located stationary shaft 9 aligned with the axis of flywheel 10 and the engine crankshaft (not shown). Shaft 9 is carried as an insert cast in place in the-die cast`cover ll-with'the aid of knurling, but any other suitable 'rigid connection between shaft 9 and the cover may be used. To facilitate alignment during assembly a loose fitting centering pin 12 extending into the bore provided tl1erefor-and not shown in the endrof` crankshaft 13 and into a similar central bore in the end ofstationary` shaft 9 may be provided. Once a properly aligned assembly has been made and the starter has been secured with the cap screws 6, the pin 12 performs no further function and therefore may be made of a material which `will quickly wear away without damage to the other parts. t

The cover 7 is notched as indicated at 14 in Fig. 3 and the base of the notch is slotted to provide an opening 15 through which a starting cord 16 may enter the cover 7 tangentially in a counterclockwise direction as shown or in the opposite direction as explained below.

lThe starting cord 16 having entered the cover 7 is wound in several turns as shown in a slot provided therefor in a starting pulley 17 rotatably mounted on the stationary shaft 9. The central part 'of the groove which receives the starting cord 16 opens into a laterally facing channel 13 in the pulley 17 so that the end of the cord 16 may be brought out at this point and clamped by means of a staple 19 disposed in a gap provided therefor in the.

collar 20 which provides one wall ofthe channel 18.

When at rest `the starting cord 16 is wound on the starting pulley 17 within the groove provided therefor as shown and when displaced from this position is rewound by a spiral flat spring 21 secured to the pulley 17 by means of the hooked en'd 22 engaged with the collar Ztl at a gap therein opposite the gap occupied by the staple 19 and passing from there in several turns to an anchorage with the post 23 secured to the cover 7.

Extending laterally from the side of the pulley 17 opposite the collar 20 is a transversely slotted boss 24 flattened on the faces adjacent the ends of the transverse slot.

Stationary shaft 9 is provided with a reduced end portion 25 which extends into the slot in the boss 24, which reduced end portion isllattened `on diametrically opposed faces. Mounted upon the end portion 25 of the shaft 9 for rotational movement with respect thereto and extending into the slot in the boss 24 is a frictionally controlled shoe retainer 26 having hook ends 27-27 for holding shoe retaining springs 28-28 in assembled relation to the remaining parts. The shoe retainer 26 is formed with at side faces in facing frictional relationship to a pair of friction Washers 29-29 backed in turn by retaining washers 30-30. The washers 29-29 and 30-30 have flattened circular openings therein closely corresponding with the cross sectional configuration of the end potrion 25 of shaft 9 so that these washers, while free to move endwise, are. held securely against rotation on the stationary shaft 9. Bearing against the outer washer 30 isa friction `^inaintaining Aspring 31 held in 3 place by retaining washer32-and snap ring 33 which engages the groove 34 in the end of shaft 9.

Loosely surrounding the shoe retaining ends 27-27 of the shoe retainer 26 is a pair of torque transmitting shoes 35-35 having outwardly bent trailing end portions 36-36 and outwardly bent leading end portions 37-37. Springs 2828 bearing against washers 38-38'act to position the shoes 35-35 as shown in Fig. 4 whenever the pulley 17 is permitted to turn in the rewinding direction that is to say opposite to that indica-ted by the arrow in Fig. 3. To ensure the return motion positioning referred to, the shoe retainer 26 is provided with a pair of shoulders 39-39 located to engage the sides of the slot in the boss 24 when the ends 27-27 are approximately centered with respect to said slot.

Mounted upon the crankshaft end 13 by means of the nut 40 and key means not shown is a starting shell 41 which extends laterally to surround the shoes 35-35 and to present thereto an internal cylindrical surface spaced a short distance from the ends 36-36 and 37-37 when the parts are in the return position shown in Fig. 4. The shell 41 may be anged as indicated at 42, which flange may be interrupted by slots as shown to engage the knotted end of a cord wound around the external end of the shell 41 if for any reason the engine must be started without the facilities furnished by the starter of this invention. Thus the starter herein described may be removed for repair or for other purposes leaving emergeucy means for starting the enginge at the disposal of the user. This is of substantial advantage where engines are used in remote locations or for military purposes where unforeseen damage may arise.

In operation the user may grasp the handle end 43 of the starting cord 16 and draw on it to cause rotation of the pulley 17 in the direction indicated by the arrow in Fig. 3. At the outset 4of this motion the boss 24 of the pulley 17 advances toward the relationship indicated in Fig. 5. While the shoe retainer 26 restrained by the friction washers 2929 remains substantially stationary, the shoulders 39-39 depart from their normal contact with the sides of the slot in the boss 24 and the shoes 35-35 slide across the flattened faces of the boss 24 in a trailing direction until the trailing ends 36-36 come in contact with the internal surface of the shell 41. The ends 36-36 having contacted the shell 41 as described then become points defining centers of rotation of the shoes 35-35 as they swing to bring the leading edges 37-37 into contact with the internal surface of the shell 41 as shown in Fig. 6. Thereafter, further motion of the pulley 17 without corresponding motion of the shell 41 is precluded unless actual sliding between the shoes 35-35 and the shell 41 occurs. Such sliding, however, normally will not occur since the tractive force between the shoes 35 35 and the shell 41 far exceeds the force required to crank the engine. This tractive force is maintained throughout the several turns of rotation of the pulley 17 which may be effected by drawing on the cord 16.

Upon starting of the engine and its sudden acceleration in the direction of the arrows shown in Figs. and 6, the shoes -35 are immediately carried forward to the relationship shown in Fig. 4 in which released position the parts will remain throughout the rewinding of the cord 16 and thereafter. The tractive force employed during cranking is developed by the corners 44-44 of the boss 24 as indicated in Fig. 6 which engage the shoes 35-35 with a cammng action at a point closer to the trailing ends 36-36 than to the leading ends 37-37. The trailing ends 36-36 are thus crowded against the internal surface of the shell 41 with substantial force greater than that exerted by the ends 37-37 and this force grows in proportion to the torque applied through the boss 24. The main contacting end of the shoes 35-35 is therefore at the trailing edge thereof while the leading end of the shoe serves primarily to furnish a fulcrum upon which the maintenance of this force depends. The shoes 35-35 thus are preferably constructed to present two definite and determined spaced contacting portions to the shell 41. The shoes 35-35, however, may be made to appear as circular segments in which case satisfactory results are obtained by constructing the shoes with an arc of greater radius than that of the shell so that a leading and a trailing contact, on opposite sides of the camming point 44, will be presented.

It is preferred, however, that the shoes '3S-35 be constructed with sharpened or reduced trailing end portions 36-36 in order that the unit pressures of contact between them and the shell 41 will be high enough to penetrate any ordinary extraneous lubricant film which may form. The tractive force obtainable in this way is approximately the same whether the internalsurface of shell 41 is lubricated or not.

The pointed or nearly pointed trailing ends 36-36 preferably are so formed that the forward faces thereof are disposed nearly at right angles to the internal surface of the shell 41, theopposite surface being at approximately thirty degrees with respect to the internal surface of the shell 41. Considerable variation in these angles may, however, be employed without adversely affecting performance. Where the lubricant film is penetrated traction is accomplished through metallic adhesion and such can be established without permanent deformation of either the shell 41 or the shoes 35-35. It has been found thatfthe zone within which such adhesion may be obtained without permanent deformation is of sufficient scope so that the shell 41 may be made of low carbon steel or even of aluminum while the shoes 35-35 may be made of hardened steel and the shell 41 will serve throughout the normal life of the engine to which it is attached without perceptible wear of the sort which interferes with proper performance of the structure.

By reason of the construction noted there is an unlimited number of positions of engagement possible. A comparatively short length of cord 16 need be withdrawn in order to produce engagement of the parts. Engagement therefore occurs without impact stress. In the event of backfiring of the engine adhesion forces may be overcome and relieving slipping of the parts can occur. In the course of such an action some metal may be removed from the internal surface ofthe shell 41 but such will not impair the usefulness of the apparatus.

The use of outwardly acting shoes which frictionally engage the internal surface of a surrounding shell, in order to transmit releasable cranking effort in one direction only, has heretofore been proposed. Such starters, however, have utilized eccentric members or shoes brought into engagement with the shell during cranking either by frictional drag acting through the running crankshaft, or by gravity effects. In either case rubbing parts remain or may remain in contact throughout the entire running period of the engine which parts soon wear to the point where dependable starter action becomes unlikely. The engageable starter parts of the apparatusof this invention are, however,.completely released upon starting of the engine.

The starter as shown and above described may be reassembled for the starting of an engine which rotates in the opposite direction. When this is done, the spring 21 is inverted and the cord 16 rewound in the opposite direction. By reason of the shape of the indentation 14 and slot 15 the cord 16 will emerge without hindrance and the handle 43 will be received in a natural position at right angles to that shown in Fig. 3. In addition the shoe retainer 26, the shoes 35-35, the washers 38-38 and the springs 28-28 are inverted as an assembly to bring the leading and trailing endsof the shoes 35-35 into correct relationship to the shell 41.

As previously noted, the starting cord 16 passes through an opening 15 in the cover 7 to a connection with the handle 43vin the plane of the groove or slot of the startingy pulley 17 whether thisy pulley is rotated clockwise or anticlockwise, and the pull on the cord 16 is usually effected in this plane.

Equipment driven by engines provided with starters of the type above described are sometimes so located that the Vstarting cord 16 either cannot be or can only with considerable 'diculty be operated by a straight pull on the cord in the plane of the drum as, for example, where the engine forms a part of an electric generator assembly such as indicated inv Fig. l and is mounted in an airplane in a position Where parts such as a wall 45 of the fuselage prevents the effective straight out pull of the cord. Also in some power driven equipment, such as lawn mowers, where the starter is located on the top portion of the equipment, the operator has to stoop down -and pull the starting cord 16 from the side. In order to the slot i5. For a right hand rotation, the threaded end of the shaft 47 passes through an opening in the vertical wall of the notch 14 and is clamped to the cover by a nut 48 as shown in Fig. 7. For left hand rotation, the threaded end of the same shaft 47 passes through an opening in the horizontal wall of the notch 14 and is clamped in position by the nut 48. The cord 16 in either case after emerging from the slot 15 may be brought into contact with the pulley 46 at any angle most convenient for the operator to exert a pull thereon, as indicated, for

v example, by the dotted line positions of the cord 16 as shown in Figs. 1 and 9.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claims.

What I claim as my invention is:

l. In an engine pull cord starter including a stationary engine mounted casing and a starter operating pull cord, said casing providing a recessed wall portion having an opening therethrough, said pull cord extending outwardly of the casing through said opening and having a handle on its outer end, a guide member, and means for mounting said member selectively in one of two positions externally of the casing on said recessed wall adjacent said opening therethrough, for cord guiding engagement by the pull cord.

2. In an engine pull cord starter including a stationary engine mounted casing and a starter operating pull cord, said casing providing a recessed wall portion having two wall elements thereof disposed such that one wall element is substantially at a right angle to the other, said recessed wall portion having an opening therethrough with a portion of the opening extending along each of said two wall elements, said pull cord extending outwardly of the casing through the opening portion along a selected one of said wall elements, a guide member, and means for mounting said member externally of the casing on the other of said wall elements in a position thereon for cord guiding engagement by the pull cord.

3. In an engine pull cord starter adapta'ote selectively for forward or reverse operation, the starter including a stationary engine mounted casing and a starter operating pull cord, said casing providing a recessed wall portion having two wall elements thereof disposed such that one wall element is substantially at a right angle to the other, the recessed wall portion having an opening therethrough with a portion of the opening exending along each of said two wall elements, said pull cord being extended outwardly of the casing through the opening portion along a selected one of the two wall elements according to the adaptation of the starter for forward or reverse operation, a guide pulley, and means for mounting said pulley selectively on the other of said two wall elements in a position for cord guiding engagement by the pull cord.

Martin Nov. 21, 1950 Heidner Sept. 4, 1951

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