US2159514A - Starter for engines - Google Patents

Description

May 23, 19 9. ABELL 2,159,514

STARTER FOR ENGINES Filed April 7, 1936 29 26 29 3' 2 ZY/l7l/l/A 2 in v Patented May 23, 1939 UNITED STATES PATENT OFFICE 3 Claims.

My invention relates to improvements in starting gear for internal combustion engines. The improvements apply to the well known type of drive, mounted on the shaft of an electric motor, which operates; because of the inertia of a pinion gear, to effect the driving engagement of the pinion with a gear on the fly-wheel of the engine and to disengage the pinion from the gear when the engine starts.

One object of my invention is to attain economy in manufacture.

Another object is to avoid the accumulation ofoil, grease, dust and grit on the pinion member by the use of external cam grooves on the latter in which foreign matter cannot collect as it does in the usual internal screw threads to a degree which prevents its engagement with the fly-wheel gear due to the inertia of the pinion. With my construction the friction or adhesion between the cam elements is always, much less than the force of inertia of the pinion member, so that the latter never fails to engage with the fly-wheel gear.

Another object is to attain rapid and positive meshing of the pinion and fly-wheel gears due to the use of a spiral spring of oblong crosssection with the longer dimension of its crosssection parallel to the axis of the spiral, so that the spring is stiif and re-acts rapidly and with great force, after being compressed in an axial direction by the butt-end engagement of the pinion and fly-wheel gear teeth, when they are moved into meshing position by the turning of the pinion.

Another object is to provide novel means for securing the spiral spring to the motor shaft, for resisting both radial and axial forces, by the engagement of the inner end of the spring with both the ends and the sides of a slot sunk in the shaft between its ends.

Other and ancillary objects of the invention will appear hereinafter.

These objects are attained by the structure illustrated by the accompanying drawing, in which Fig. l is a perspective view of the starter drive;

. Fig. 2 is a side view, with a portion in section;

Fig. 3 is a sectional side View in a plane transverse to that shown by Fig. 2;

Fig. 4 is a transverse section on the line A--A of Fig. 2;

Fig. 5 is a transverse section on the line BB of Fig. 2; and

Fig. 6 is a transverse section on the line C-C of Fig. 2.

Similar numerals refer to similar parts on the several views.

The starting motor I is attached to a stationary part of the internal combustion engine, of which 2 is a gear affixed to its fly-wheel. The pinion member 3 is mounted on the starting' motor shaft 4, on which it is free to turn and also to slide. The driving member 5 is also free to turn and slide on the shaft 4. The spiral spring 6 is afiixed at its inner end tothe shaft 4 and at its outer end to the driving member 5 by hooking into a slot in the arm 39. The helical spring 1, enclosed in the annular space between the pinion member 3 and the shaft 4, abuts at one end on the sleeve 8 on the shaft 4 and at the other end on the bushing 9, retained in the outer end of the pinion member 3 by the spring ring I0 which engages with a groove of semicircular cross-section on the inside of the pinion member.

The collar II is secured to shaft 4 by the flat key l2 having an integral stud l3, inserted in the hole l4 in the shaft 4. The end of the key 12 is bent at I5 to engage with the collar H. A segmental sleeve l6, integral With the collar II, is inserted between the inner convolution of the spiral spring 6 and the shaft 4, holding the inner end of the spring in close contact with the shaft. The inner end of the spring is bent in radially at IT and is curved to fit the semi-circular keyway IS in the shaft 4. The inner convolution of the spring does not abut against the collar H, so that there is no tendency for the latter to be slipped off the end of the shaft 4 due to the axial compression of spring 6, which forces the edge of its bent-in end l1 against the curved surface of the keyway I8. The flat side of the bent-in end I! is also in contact with one side of the keyway I8, so that the bent-in end of the spring takes the radial as well as the axial strains to which the spring is subjected. The segmental sleeve I6 is subjected only to compression strains.

While it is common to employ the bent-in end of a spiral spring for affixing it to a shaft by means of a keyway to take the radial strains and to employ a collar or other abutment to take the axial strains, it is believed that it is novel to utilize the sides and the ends of a keyway, sunk in a shaft between its ends, to take the radial and axial strains, respectively. In order to assemble the spiral spring on the shaft, with a keyway so located, the space between the end of the spring and the opposite side of its inner convolution must be as great as the diameter of the shaft,

so that the spring can be slipped along the shaft. When the bent-in end of the spring has been fitted in the keyway, the insertion of the segmental sleeve or filler holds the spring end in 5 contact with both the ends and the sides of the keyway so that the spring is affixed to the shaft to withstand both radial and axial strains.

The fillers between shaft and spring as employed by others do not draw the end of spring into engagement with a keyway sunk in a keyway between its ends. They cannot, therefore, perform the dual function of securing the spring to withstand both radial and axial strains. The simple, strong and compact construction which I employ is believed to be novel in principle.

Integral gear teeth I9 are formed on the end of the pinion member 3 adjacent to the gear 2 Mixed to the engine fly-wheel. The gear teeth are chamfered to facilitate meshing. In the barrel of the pinion member are out two diametrically opposite, helical cam- grooves 20 and 2|, with which engage, respectively, segmental runners .22 and 23, formed on the arms 3| and 32 of driving member 5. The cam- grooves 20 and 2| are, in effect, a double screw thread whereby the pinion teeth I9 are urged into mesh with the teeth on gear 2 when the pinion member 3 is moved to the right by the right-hand rotation of starting motor, shaft and the driving member 5, as observed from the left. The meshing movement is due to the inertia of the pinion member 3, which, as above stated, is free to turn and also to slide on the motor shaft 4, as the inertia is greater than the friction between the cam- grooves 20 and 2| and the runners 2-2 and 23 and the opposition of the light spring 1.

When the pinion teeth l9 abut against the teeth on gear 2 the continued rotation of the runners 22 and 23 in the cam-grooves 2|! and 2| cause the driving member 5 to be moved to the left, thereby causing the axial edgewise deflection of the spiral spring 6 and the cushioning of the impact between the teeth. The further rotation of the driving member 5 increases the friction between it and the pinion member 3, causing it to turn into the meshing position. When that .occurs the reaction of the sprial spring 6 from its edgewise deflection is forceful and rapid. Consequently, the pinion teeth are moved further into mesh during the moment when the spring reacts than they are moved by the weaker springs which are compressed flatwise, as in other starter drives. The deeper meshing reduces the tendency to chip the ends of the gear teeth.

After the pinion 3 has partially meshed with the gear 2 the .continued rotation of the driving member 5 slides the pinion member fully into mesh, whereupon the leading surfaces .of the runners 22 and 23 meet, respectively, the arms 24 and 25 on the bushing 9, which project through slots in the end of the pinion member 3 and close the cam grooves 20 and 2|, respectively. The

contact is cushioned by the torsional deflection of the spring 6, which is sensitive to such defiection because it bends the spring flatwise. A

spring of the proportions shown is so sensitive to torsional strains that the gears do not clash if the starter is inadvertently actuated when the engine is running, whereas with starters having relatively stiff springs which are deflected edgewise by the torsional strain which occurs, the

gears clash so severely that it is common for the teeth to be chipped or broken.

Although flatwi'se wound spiral springs have been used in other starters, they have been employed only for their torsional flexibility. It is believed that it is novel to employ such a spring for yielding to torsional strains and also to axial forces. By taking advantage of the two characteristics of that type of spring, an improvement 5 in operation has been attained.

When the engine has been started, the peripheral speed of its fiy-wheel gear 2 is greater than imparted to thepinion 3 by the starting motor, so that the cam action which engaged the 10 pinion is reversed and the pinion is returned to the position shown by the drawing, with its left end abutting against the driving member 5. Although the first pcwer stroke of the engine (more especially if it has a light fly-wheel) may reverse 15 the cam action so suddenly that the end of the pinion comes sharply in contact with the driving member, it is restrained by the wedge action be,- tween the cam member and the runners 22 and 23 from rebounding. The helical spring 1, which 20 has a small degree of initial compression, holds the pinion out of mesh, in the position shown.

The driving member 5 maybe made of a single piece of sheet metal, as shown by the drawing, to attain lightness and economy of manufac- 25 ture. The flat blank from which it is formed consists of two discs 26 and 2'! joined by an integral bar 28. Two diametrically opposite-radial arms 3| and 32 are formed on disc 25 and two diametrically opposite radial arms 29 and 30 30 are formed on disc 21. A right-angle bend is made in the bar 28 at the point Where it joins disc 26 and another right-angle bend is made at the point where it joins disc 21, so that the two discs are parallel. Disc 26 has a cen- 35 tral bearing on shaft 4 and disc 21 has a concentric bearing on collar so that the driving member 5 may turn and slide freely on the shaft 4, to the degree permitted by spring 6. The concentric bearing on collar maintains 40 the driving member in alignment with the axis of the shaft and preserves the annular clearances between the diametrically opposite edges of the runners 22' and 23 and the bottoms of the cam grooves 20 and 2|. The runners therefore 45 make contact only with the sides of the cam. grooves, thereby reducing the friction between the driving member 5 and the pinion member 3 to a minimum and insuring the engagement of the latter with the fly-wheel gear 2 due to 50 preponderance of the inertia of the pinion memher over the friction between it and the driving member.

The arms 3| and 32 are bent at right-angles at the points where they join the disc 2B and 55 are also bent at right-angles near their ends to form the runners 22 and 23. The arms 29 and 30 are bent at right-angles at the points where they join the disc 21 and overlap the arms 3| and 32, to which they are attached by rivets, as 0 shown, or by welding. The one-piece box-truss structure so formed, encloses the spiral spring 6 and limits its tmwinding when the pinion member is spun with great velocity out of engagement with the fly-wheel gear 2 by the sud- 65 den starting of an engine with a light fly-wheel. Because of the violence of this action due to the large step-up gear ratio of the gear 2 and the pinion l9, it is desirable to limit the unwinding of the spring, thereby reducing the strain to 70 which it is subjected.

What I claim is:

1. In a starter for engines, the combination of a motor-driven shaft, a sleeve with gear teeth on one end, mounted on the shaft and adapted 7-5 to turn and slide thereon, a driving member also mounted on the shaft and adapted to turn and slide thereon under the control of a spring with one end attached to the shaft and the other end attached to said driving member comprising two parallel discs concentric with the shaft, said discs being connected by an integral bar and each having two similar diametrically opposite arms, the arms on one disc terminating in runners co-acting with diametrically opposite cam grooves in the aforesaid sleeve, the arms on the other disc overlapping the arms on the first disc and being aflixed thereto.

2. In a-starter for engines, the combination of a motor-driven shaft, a sleeve with gear teeth on one end, mounted on the shaft and adapted to turn and slide thereon, a driving member also mounted on the shaft and adapted to turn and slide thereon under the control of a spring with one end attached to the shaft and the other end attached to said driving member comprising two parallel discs concentric with the shaft, said discs each having two similar diametrically opposite arms, the arms on one disc terminating in runners co-acting with diametrically opposite cam grooves in the aforesaid sleeve, the arms on the other disc overlapping the arms on the first disc and being afl'ixed thereto.

3. In a starter for engines, the combination of a motor driven shaft, a sleeve with gear-teeth on one end, mounted on the shaft and adapted to turn and slide thereon, a driving member also mounted on the shaft and adapted to turn and slide thereon under the control of a spring with one end attached to the shaft and the other end attached to said driving member comprising two parallel discs concentric with the shaft, said discs being connected by two similar diametrically opposite arms provided with runners coacting with diametrically opposite cam grooves in the aforesaid sleeve.

ARTHUR H. ABELL.

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