US2975777A - Starter mechanism - Google Patents

Description

March 21, 1951 c. J. GusrAFssoN STARTER MECHANISM 2 Sheets-Sheet 1 Filed 00's. 5, 1959 3 fig@ INVENTOR I CARL J. GUSTAFSO/V ATTORNEY March 21, 1961 c. J. GUs'rAFssoN 2,975,777

STARTER MECHANISM Filed Oct. 5, 1959 l 2 Sheets-Sheet 2 f2 4W \\\4L\\\\\\T 46 M' 34 sa 42 :1,434 66 Il 3@ u I 42 f i5 //ar 70 E I l 7a I E I i 56 I |I lf: 2 z 1 46 46 nl ,I

l: ZE. Z INVENTOR @A7/6; J. GUSTA/USUN @www ATTORNEY Aff.

2,975,777 STARTER MECHANISM Carl J. Gustafsson, Jackson, Mich., assignor to Yard-Man, Inc., Jackson, Mich., a corporation of Michigan Filed oct. Is, i959, ser. No. 844,281 3 claims.. (121.1234485) The invention relates `to starters for internal combustion engines and particularly pertains to pfoot operated devices commonly known as kick starters;

Engines such as used on motorcycles, motor scooters, lawn mowers, etc., have often employed foot operated starters consisting of a lever mounted arcuate gear segment engageablewith a pinion Lgear operably connected to the engine crankshaft. Because of space limitations, cost and mechanical considerations, the lever mounted gear segment starters of conventional construction are unable to rotate the engine more than a few revolutions with each actuationof the starter. As -four cycle engines ignite only once every two crankshaft revolutions, difficulty is often experienced in starting such engines with kick starters because adequate engine rotation is not produced.y To partial-ly` compensate for this deticiency, some engine manufacturers employ eXtra heavy ilywheels to increase thel crank inertia; however, such modification adversely alfects engine acceleration.

The invention contemplates a kick starter wherein the usual objections to such starters are overcome by employing a linear gear rack of such length that a single stroke of the rack produces several rapid revolutions of the engine crankshaft which will thus always include the power stroke of the engine. To insure proper engage` ment of .the gear rack with a pinion gear aflixed to the starter, the rack is mounted for linear movement 'and the mounting structure is of simple, concise construction which occupies little space.

It is thus an object of thel invention to provide-a manually operated starter for internal combustion engines which produces improving cranking characteristics on a single stroke of the starter. i

Another 4object of the invention is to provide a manually operated starter for internal combustion engines which employs a linear gear rack which is translated in an axial direction to provide the starting stroke.

,Patented Mar. 2i, rear Fig. 2 s a detailed elevational view .taken from the right of Fig. l along the line l'I-II, and

Fig. 3 is a sectional plan view of the starter taken along the line III- III of Fig. 1.

The invention is described and disclosed as a foot operated or kick starter; however, it will be appreciated that it is within the scope of the invention to provide means for employing the novel apparatus in a hand operated starter as Well.

The starter of the invention maybe used with all types of engines of a size which normally employ kick type starters and is commercially employed to start the engine of a motor scooter. It is in `this environment that the invention will be described.

Referring to the drawings, the relationship of the starter assembly, generally designated at 10, to the engine and scooter framework will be apparent. The scooter frame includes a pair ofV spaced, parallel, longitudinal support members 12, one of which appears in Fig. l, which straddle the rear wheel and are affixed to the front wheel support in the conventional manner. members 12'are interconnected by transverse channels 14 which support an internal combustion engine 16. Engine 16 is of conventional design and is usually of the four cycle type. A pinion gear 18 is aflixed to the crankshaft ofthe engine and the crankshaft is connected to the rear wheel of the scooter by a chain drive or other known power transmission apparatus. The seat of the scooter is supported upon a framework including vertical elements 20, aixed to each of the members 12, and a bar 22, Fig. 2, interconnects the elements 20 near the upper regions thereof `to strengthen the seat framework and alsoacts as a starter support, as will be later apparent. v The starter l10 includes a guide shaft 24 of square cross sections which is affixed to the scooter framework between the front channel 14'and the bar 22. A bracket I' may be welded lto the lower end of shaft 24 which is A further object of the invention is Ito provide a manu- I ally operated starter employing .alinear gear rack wherein the rack is mounted for axial and transverse movement whereby the initial operation of the starter producesthe transverse movement'for alignment with the engine elements andL release of the starter by the operator automatically disengages the rack from the engine elements.

Yet another object of the invention is to provide a manually operated starter of concise, economical construction which may be manufactured largely of stampings and which is dependable in operation.

rIihese and other objects of the invention arising from the structural arrangements of an embodiment thereof will be apparent from the following description and accompanying drawings wherein:

Fig. 1 is an elevational side view of a starter in accordance with the invention showing the starter components in various positions during the operation thereof in dotted lines.

Vbar 22 by a bolt 30. It will be noted that the bar 22 is flattened to facilitate connection of the yokeV thereto.` A space is purposely provided between the upper end of shaft 24 and the base of yoke 26 to provide clearance for the return spring, as will be described.

A carriage 32 is slideably supported on shaft 24 and consists of a pair of stamped members which, when welded together, form an opening complementary to the cross section of shaft 24 for a close sliding fit thereon and also defines an ear 34 to which the other starter structure may be aflixed. An abutment surface 36 is defined on t-he lower edge of ear 34, Fig. l, to position the rack, as will be later described.

A pair of pivot pins 38y and 40 are mounted on the vear 34 in vertically spaced relation and a pair of links riage 32 and consists of a horizontal web 52 which in-A terconnects the leg portions 46. As will be apparent from the drawings, the foot pedal 44 is pivotally aixed to the carriage 32 by the pivot pin 40 which extends through both of the leg portions.

A linear gear rack 54 having gear teeth 56 is aiixed to links 42 and the foot pedal portions 50 by pivot pins 58 and 60, respectively, for movement with the carriage 32.

The

The distance from the axes of pin 38 to pin 58 is equal t0 the distance separating the axes of pins 40 and 60 and the planes including these respective sets of axes are parallel, whereby the links 42 and foot pedal leg portions 50 define a parallelogram linkage system supporting the rack 54. A shoulder 62 is formed on the rack parallel to the abutment surface 36 for selective engagement therewith. It will be thus apparent that depressing the web 52 will translate the rack transversely, yet the plane of the rack teeth will always remain parallel to the guide shaft 24 as the axes of pins 38 and 40 are equal distances from the guide shaft.

Means are provided for returning the starter apparatus to the initial position after the starting stroke and this means preferably takes the form of a negator type spring 64 which is supported within the yoke 26 upon a bolt 66. Spring 64 consists of a broad coil of pre-stressed and formed spring steel which, in the free form, assumes a coiled shape. One end of the spring is aiiixed to carriage 32 by a `rectangular ring 68 which passes through a hole in the ear 34 and hence the spring 64 will always exert an upwardly directed force on the carriage. While other types of return springs might be employed for this purpose, the negator type spring is preferred in that little space is required for a spring capable of considerable extension and because this type of spring produces a substantially constant force at all .positions of extension which permits uniform operation of the starter and prevents an exces sively rapidV carriage return.

A pair of tension springs 70 are interposed between ring 68 and foot pedal leg portions 50 to bias the foot pedal web portion upwardly and automatically disengage the rack teeth from the pinion gear 18.

The starter of the invention operates in the following manner: Because of the springs 64 and '70 the starter components will be in the position shown in the full lines of Fig. 1. Thus `the carriage 32 is in the uppermost position and engages the lower edges of yoke 26 and the rack will be in the left most position such that teeth 56 clear the teeth of pinion 18. To start thev engine the operator will place his foot upon the web 52 of pedal 44 and push the pedal downwardly with a continuous motion. Upon placing the foot upon the web, the initial application of force will move the pedal 44 to the dotted line position wherein the rack 54 will be moved toward pinion gear 18 in meshing alignment therewith. This motion is against the force of springs 70 and will not cause movement of the carriage. Upon engagement of the shoulder 62 with abutment surface 36 proper radial alignment between the rack teeth 56 and pinion gear is achieved and further pivoting of the foot pedal is prevented. The carriage 32 now begins to slide down the shaft 24. As the carriage moves downwardly, the gear rack 54 rotates the gear 18 and cranks the engine 16. Due to the length of the rack in relation to the diameter of the pinion gear, the engine crankshaft will be rotated through several complete revolutions during engagement with the rack and the inertia of the flywheel will add to the cranking action.

At the end of the starting stroke the carriage 32 will strike the bracket at the lower end of shaft 24 and the rack will then be out of engagement with the gear 18 as shown in the dotted lines of Fig. l. To return the carriage to the original position, the operator removes his foot from web S2 which permits springs 70 to raise the foot pedal and move the rack to the left, Fig. 1. The spring 64 will draw the carriage upwardly at a uniform Velocity and as the rack 54 is in the retracted position, the rack will not engage nor interfere with the pinion gear 18 during the return stroke. -If the engine failed to start, the pedal 44 is again depressed and the cycle repeated.

The starter of the invention has proven to be very effective in producing adequate cranking of `the engine, and -as the components Iare constructed of stampings and available stock, manufacturing costs are reduced over conventional constructions requiring castings and forgings. The parallelogram rack mounting insures proper engagement of the rack and pinion and this feature, used in conjunction with the negator return spring and automatic retraction of the rack from the pinion, results in a smooth and safe operating motion.

I claim:

1. A starter for internal combustion engines having a starting pinion gear, said starter includ-ing a guide shaft, a carriage supported on said shaft for slideable movement thereon, a gear rack adapted to selectively engage the starting pinion gear, a pair of link elements pivotally mounted at one end on said carriage and pivotally mounted at the other end tov said rack constituting a parallogram linkage mounting said rack upon said carriage, a foot pedal portion formed on one of said links, sto-p means formed on said carriage cooperable with stop means dened on said rack limiting pivoting of said links, said stop means being located such that initial depression of said foot pedal link portion will Ipivot said links to align said rack with the pinion gear and continued depression axially translates said carriage and rack to engage said rack with the gear for the rotation thereof.

2. In a starter as in claim 1 wherein a return spring of the negator type is interposed between said guide shaft and said carriage to return said carriage to the initial position.

3. In a starter as in claim 2 wherein said rack is located on one side of said guide shaft and said foot pedal portion is located on the opposite side of said guide shaft.

References Cited in the tile of this patent UNITED STATES PATENTS 1,127,710 Woods Feb. 9, 1915 1,879,130 Diago Sept. 27, 1932 2,109,281 Bosma Feb. 22, 1938 2,562,085 Dry etal July 24, 1951 FOREIGN PATENTS 458,987 France Aug. 21, 1913 OTHER REFERENCES The Negative Spring, Product Engineering, July 1949, published by McGraw-Hill (pp. 136-140).

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