BACKGROUND OF THE INVENTION
The invention pertains to recoil starters for heavy duty internal combustion engines using a starter rope wherein the starter rope is coiled within a rope receiving groove defined in a pulley operatively connected to engine driving clutch dogs.
Recoil starters for internal combustion engines of less than 7 HP have been widely employed, and such recoil starters for such small engines meet manual starting requirements and have proven fully satisfactory with engines of this size range. The ability of the recoil starter to automatically rewind the starter rope on the pulley has provided a convenience long appreciated in the art and recoil starters have been developed which provide dependable operation over long life cycles and such starters as shown in my U.S. Pat. Nos. 3,375,813 and 3,375,814 have been mass produced and have enjoyed widespread commercial acceptance.
The increased popularity of recreational vehicles such as snowmobiles, all terrain vehicles, and the like has increased the production of larger horsepower engines such as in the range of 7 to 80 HP. Such engines, if not electrically started, may be cranked with recoil starters, but due to the size of the engine a heavier duty construction is required than has been previously available. Also, due to serious vibration problems occurring in larger horsepower engines the vibration forces and wear imposed upon recoil starters used with larger engines are significantly greater than with smaller engines. Accordingly, the design and construction of starters for use with larger internal combustion engines is somewhat different than that employed with smaller engines, and many design features of starters used with smaller engines are not available with the larger size of engine.
Recoil starters for larger capacity engines utilizing heavy metal starter ropepulleys are subjected to vibrations and frequencies which often damage the pulleys and other starter components. Furthermore, recoil starters using radially extendable dogs must be of a more rugged construction, and capable of a more positive operation than afforded with previous starters. As the forces required to crank larger engines may be very high due to the size and compression of the engine, high tension forces within the starter rope are produced during cranking which often produce a binding of the starter rope within the rope pulley groove during cranking which further adds to the force required to start such engines.
The problem of the starter rope binding within the pulley groove during engine cranking has been treated in my U.S. Pat. No. 3,375,814, and the structure disclosed therein is suitable for minimizing and preventing rope bind when cranking small horsepower engines. Hwever, the tension forces produced within starter ropes when cranking larger sizes of horsepower engines creates very high tension forces upon the starter rope, which causes rope binding, and other problems which are not completely solved by the rope pulley construction shown in U.S. Pat. No. 3,375,814.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a recoil starter for larger size internal combustion engines wherein superior resistance to vibration and wear is produced in an economical starter having dependable operating characteristics.
A further object of the invention is to provide a recoil starter having a positive operating clutch mechanism for cooperating with engine flywheel mounted structure utilizing radially extendable dogs which are readily extended outwardly in a positive manner for enggaement with a flywheel mounted clutch cup, and are locked in the declutching position to prevent an inadvertent engagement of the dog with the cup, and also minimize dog wear during engine vibration.
A further object of the invention is to provide a recoil starter for internal combustion engines utilizing a synthetic plastic rope pulley having a rope receiving groove or recess of unique configuration which minimizes binding and rope laying problems during recoiling and rewinding wherein a predetermined orientation of the rope coils in the rope groove is achieved during recoiling. The controlled orientation of the coils in the rope groove during recoiling prevents rope binding during cranking and insures consistent starter rope tension characteristics during each cranking operation.
In the practice of the invention a pulley shaft is mounted within a starter housing adapted to be connected to the engine shroud concentric to the flywheel axis of rotation. Air passage means are defined in the starter housing wherein the usual circulating vanes mounted upon the flywheel may draw air through the starter housing for engine cooling purposes. A synthetic plastic pulley of a light weight is rotatably mounted upon the shaft having a recess or groove defined therein which includes a radial shoulder having an axial dimension one half that of the rope groove, and rope guide means are defined in the rope groove to control the manner in which the rope is coiled within the groove during rotation of the rope pulley during the recoiling operation. Dogs are pivotally mounted upon the pulley for selective engagement with a cup member mounted upon the engine flywheel coaxial with the pulley shaft. The dogs are located within the cup, and a dog cam mounted upon the shaft for frictional rotation thereto controls the radial position of the dogs. The cam dog is of a generally flat or plate configuration and includes peripheral edge surfaces which pivot the dogs outward during rotation of the pulley in a cranking direction, and an edge surface defined upon the cam dog serves as an abutment for cooperating with a surface defined on the dogs during recoiling, and at rest, to maintain the dogs in their inactive or radially inward position upon the pulley rotating in a recoiling direction.
A starter construction in accord with the invention may be manufactured and assembled with conventional techniques, and yet the requisites necessary with starters used with relatively large horsepower engines are met.
BRIEF DESCRIPTION OF THE DRAWINGS
The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein:
FIG. 1 is a diametrical, elevational, cross-sectional view of a recoil starter constructed in accord with the invention,
FIG. 2 is a sectional, bottom view taken along Section II--II of FIG. 1,
FIG. 3 is a detailed sectioned view of the dogs, cam dog and flywneel cup similar to that of FIG. 2, but illustrating the dogs in the cup engaging and engine cranking position,
FIG. 4 is an elevational, sectional, diametrical view of another embodiment of recoil starter constructed in accord with the invention,
FIG. 5 is an underside view of the starter of FIG. 4 illustrating the dogs in the retracted position, the cup being shown in section for purpose of illustration,
FIG. 6 is a detailed view of the dogs, dog cam and engine clutch cup illustrating the dogs in the cup engaging position,
FIG. 7 is an elevational, sectional view of a starter in accord with the invention illustrating the starter rope and rope at the end of a cranking operation, all of the rope coils having unwound from the pulley groove, and prior to rotation of the pulley in a recoiling direction,
FIG. 8 is similar to FIG. 7, and illustrates the relationship of the starter rope and the pulley at the completion of the recoiling of a single rope coil,
FIG. 9 is similar to FIG. 8 illustrating the relationship of components at the completion of the recoiling of two coils of starter rope on the rope pulley,
FIG. 10 is an enlarged, elevational, detail sectional view taken through the rope pulley periphery and groove along Section X--X of FIG. 7, and
FIG. 11 is an enlarged, elevational, detail sectional view taken along XI--XI of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Two embodiments of recoil starters utilizing the concepts of the invention are disclosed in the drawings. The embodiment illustrated in FIGS. 1 through 3, and the embodiment illustrated in FIGS. 4 through 6, differ primarily in the fact that the starter shown in FIGS. 1 through 3 is for use with smaller horsepower engines than the starter illustrated in FIGS. 4 through 5. The basic principals of operation, and the novel aspects, of the two starter embodiments are identical, and both embodiments use a rope pulley having the features described in detail with respect to FIGS. 7 through 11.
With reference to the starter illustrated in FIGS. 1 through 3, the starter includes a housing 10, which is usually of a cast metal construction, which is bolted to the engine shroud encompassing the flywheel. The housing 10 includes bolt receiving holes 12, and a plurality of passages 14 are defined in the housing to permit air to flow through the starter housing into the flywheel chamber under the influence of the flywheel vanes, not shown, formed on the flywheel in the usual manner.
The housing also includes a rope bushing 16 which is in central alignment with the groove of the rope pulley, as will be later described.
Internally, the housing 10 includes a boss 18 having a bore defined therein for receiving the rope pulley shaft 20 which extends downwardly from the boss 18. The shaft 20 is coaxially related to the engine flywheel 22, the flywheel axis defining the axis of rotation for the flywheel drive cup 24 bolted to the flywheel in the known manner.
A rope pulley 26 is rotatably mounted upon the lower portion of the shaft 20 and the pulley includes a central bore in which the sleeve bearing 28 is located for providing a wear surface between the pulley and shaft 20. The pulley 26 is maintained upon the shaft by the shouldered bolt 30, threaded into the end of the shaft, and the washer 32.
The rope pulley 26 is formed from a synthetic plastic material, such as a co-poly carbonate which is reinforced with glass fiber. The material made by General Electric Company known as Lexan is suitable. Such synthetic material provides a light weight, has high strength characteristics as required in this type of environment, and the use of the lightweight synthetic material in the rope pulley is of important significance in that the relatively large internal combustion engines with which the starters in accord with the invention are employed produce severe vibrations. By making the pulley as light as possible adverse effects produced by the vibration are minimized, and the fact that the hardness of the material of the pulley substantially corresponds to the hardness of the filaments of which the starter rope is formed minimizes wear on the rope pulley. The advantages of this relationship are discussed in my U.S. Pat. No. 3,375,814.
The rope pulley 26 is of circular configuration and includes a rope receiving groove 34 in which the starter rope 36 is received. The inner end of the rope is inserted through a rope opening defined in the groove, and this rope end is knotted to affix the rope to the pulley. The outer end of the rope 36 extends through the rope bushing 16 and is attached to the handle 40 exteriorly accessible with respect to the housing 10.
The rope pulley 26 includes a hub in which a pair of pivot pins 42 are mounted and extend downwardly to serve as pivot supports for the clutch dogs 44. The dogs 44 are pivotally mounted upon the pins 42 and are maintained thereon by snap rings 46 which are received within annular recesses defined upon the pins. A torsion spring 48 is disposed about each pin 42 having an end affixed with respect to the rope pulley, and another end 50, FIG. 2, bears upon the dog to impose a biasing force on the dog to pivot the dog inwardly toward the disengaging position.
The configuration of the dogs 44 is best appreciated from FIGS. 2 and 3, and the dogs include an outer clutch cup engaging surface 52 defined at the forward end of the dog with respect to the direction of dog rotation during engine cranking. The dogs also include a surface 54 adjacent the clutch engaging surface 52 for engagement with the dog cam during the initial phase or cranking, and an abutment surface 56 which is substantially radially disposed with the associated dog pivot axis is defined upon each dog on the opposite side of its pivot axis with respect to the cup engaging surface 52. The dogs 44 are preferably die cast or formed of a sintered metal.
Actuation of the clutch dogs 44 is achieved by a dog cam plate 58 rotatably mounted upon the shaft 20 by means of the shouldered bolt 30. The dog cam is formed of sheet steel, and is of a generally flat configuration having a hub portion 60 set downwardly with respect to the dog cam peripheral portion. The periphery of the dog cam will be appreciated from FIGS. 2 and 3, and includes a dog engaging surface 62 adapted to engage the dog surface 54 to radially outwardly position the dogs to produce engagement of the dogs with the flywheel clutch cup 24.
The dog cam configuration also includes a circular surface 64 which provides clearance for the dogs 44 and permits free rotation between the dogs and the dog cam, to a limited extent. Additionally, the dog cam 58 includes a dog retaining surface 66 for each dog mounted upon the pulley which cooperates with the dog abutment surface 56 when the pulley is rewound in a rope recoiling direction, as ilustrated in FIG. 2. When the surfaces 54 and 66 are in engagement, as in FIG. 2, the dogs 44 are not capable of clockwise rotation with respect to their associated pivot axis, FIG. 2, and thus are positively retained or locked against clockwise rotation, which would permit the dog surfaces 52 to engage the flywheel clutch drive cup 24.
Rotation of the dog cam plate 58 relative to the shaft 20 is frictionally retarded due to the existence of friction forces produced by the compression spring 68 interposed between the washer 32 and the cam hub portion 60. The biasing force produced by the spring 68 serves as a "brake" to resist rotation of the dog cam plate.
Rotation of the rope pulley 26 in a recoiling direction is produced by a coil spring 70 disposed about the housing boss 18 having one end connected to the pulley, and another end connected to the housing boss. Thus, as the starter rope 36 is tensioned and the rope pulley is rotated in a cranking direction, the spring 70 is wound to store a force sufficient to rotate the pulley in a recoiling direction once the tension in the starter rope is released. In the disclosed embodiment the coil spring 70 is mounted within a housing 72, and the mode of attachment of the spring and its housing to the rope pulley is as disclosed in my U.S. Pat. No. 3,375,814.
The drive cup 24 is attached to the flywheel 22 by bolts, and the drive cup includes an axially extending wall portion 74 which is of sufficient height to receive the dogs 44 and dog cam plate 58 as is appreciated from FIG. 1. The wall portion has a plurality of lanced teeth 76 defined therein in a manner as will be appreciated from FIGS. 2 and 3.
In operation, the starter components are initially oriented as shown in FIGS. 1 and 2. The rope pulley 26 is fully recoiled under the influence of the recoil spring 70, and the starter rope is fully coiled within the pulley groove 34. Under these conditions the handle 40 is disposed adjacent the rope bushing 16 as illustrated in FIG. 1. The dogs 44 are related to the dog cam plate 58 as shown in FIG. 2 wherein the abutment surface 56 is in engagement with the retaining surface 66 preventing clockwise rotation of the dogs, and insuring that the dog surfaces 52 will not be in engagement with the drive cup teeth 76. In this relationship the engine may be at rest, or running, and if the engine is running, the fact that the dogs cannot be engaged by the rotating cup teeth prevents undesirable noise, or wear on the dogs.
Upon the operator grasping the handle 40 and tensioning the starter rope, the rope pulley will rotate in a counterclockwise direction, FIG. 2, which causes the dog ends 52 and the clutch dogs 44 to move in a counterclockwise direction with respect to the dog cam plate 58. Such relative movement continues until the dog surfaces 54 engage the cam surfaces 62, which causes the dogs to pivot in a clockwise direction about their respective pivot pins, and radially locate the dog surfaces 52 for engagement with the cup teeth 76, as shown in FIG. 3. Upon engagement of the dog leading surfaces 52 with the cup teeth 76 the dogs will cause the drive cup 24 to rotate and thereby crank the engine for starting the same.
When the engine starts, the drive cup 24 will rotate faster than the rope pulley 26, causing the inclined surfaces 78 of the cup teeth to engage the dog outer surfaces 80 and pivot the dogs inwardly out of an interfering relationship with the cup teeth 76. In this manner the dogs 44 are quickly cleared form the cup teeth, and the biasing force imposed on the dogs by the springs 48 further insure that the dogs will be held from engagement from the cup teeth.
The initial rotation of the dogs 44 in a counterclockwise direction due to the force exerted by the inclined surfaces 78 causes the dog surfaces 54 to be pressed against the dog cam surfaces 62, causing a counterclockwise rotation of the dog cam, and thereby permitting the counterclockwise rotation of the dog. Upon the operator releasing the handle 40, or reducing the tension therein, the spring 70 recoils the rope pulley, causing the dog pivot pins to rotate in a clockwise direction, FIG. 2, wherein the dogs relate to the dog cam as shown in FIG. 2 and are positively prevented from engaging the cup teeth 76 due to the interengagement between the dog abutment surfaces 56 and the dog cam retaining surfaces 66. Thus, during engine operation the dogs 44 will be locked in the "retracted" position and a positive holding of the dogs is achieved.
The starter embodiment illustrated in FIGS. 3 through 6 is of a heavy duty construction, and is identical, in many respects to the previously described embodiment and equivalent components are identified by primed reference numerals. In this embodiment a spring pin 82 is attached to the housing 10' whereby the outer end of the recoil spring 84 may be attached to the housing by means of the pin, and the inner end of the recoil spring, not shown, is attached to the rope pulley 26'.
As will be appreciated in FIGS. 5 and 6, three dog pivot pins 42' and clutch dogs 44' are mounted upon the rope pulley, and the dog cam plate 58' includes three radially extending lobes upon which the appropriate surfaces are defined for producing a dog and dog cam operation and relationship identical to that previously described.
The engine flywheel mounted clutch cup 86 is of a heavy duty cast construction and includes a plurality of teeth defined therein for selective engagement with the dog cup engaging surfaces 52'.
Operation of the starter illustrated in FIGS. 4 through 6 is identical to that previously described with respect to the operation of the starter shown in FIGS. 1 through 3 except that three dogs 44', rather than two, are simultaneously operated by the dog cam plate 58'.
Both of the previously described recoil starter embodiments utilize a rope pulley 26 having a pulley groove 34 defined in the periphery thereof which is of a unique configuration for controlling the recoiling of the starter rope and minimizing the likelihood of starter rope problems during cranking, such as binding of the rope within the pulley groove. The configuration of the starter pulley groove, and the relationship between the starter rope 36 and the pulley groove, is best appreciated from FIGS. 7 through 11. The pulley groove 34 is defined by a pair of radially extending pulley sides 90 and 92 which are spaced apart a distance substantially equal to twice the diameter of the starter rope 36. The base surface 94 constitutes a recess having an axial width substantially equal to the rope diameter, and a radial depth approximately equal to the rope radius. Adjacent the base surface 94, an annular shoulder surface 96 is defined having a radius greater than the radius of the base surface by a distance approximately equal to that of the rope radius. It will be noted that the base surface 94 is formed with a concave surface, while the shoulder surface 96 is of a substantially cylindrical configuration.
The rope opening 38 defined in the rope pulley intersects the base surface 94, and just to the right of the opening 38, FIG. 7, a rope guiding depression 98 is defined in the pulley groove which intersects the base surface 94 adjacent the pulley side 90 and obliquely extends across the pulley groove to the pulley side 92. The shoulder surface 96 is recessed in the region to the left of opening 38, FIG. 7, and depression 98 extends into shoulder 96. The depression 98 defines a pulley groove portion 100 of a generally triangular configuration having a cross section that will be appreciated from FIG. 10.
The rope bushing 16 has an axis substantially centrally located with respect to the pulley groove sides 90 and 92, and the relationship of the rope 36, pulley 26 and pulley opening 38 when the starter rope is substantially fully extended, and prior to significant recoiling of the rope on the pulley, is shown in FIG. 7. As illustrated in FIG. 7, that portion of the rope indicated at 102 between the guide bushing 16 and the opening 38 is aligned, and partially received within the groove base surface 94.
As the pulley 26 rewinds under the influence of the recoil spring 70, the pulley opening 38 will be moving to the right, FIG. 7, and the first coil of the rope lies within the base surface 94 in that the base surface defines the innermost portion of the pulley groove, and also due to the alignment of the opening 38 with base surface 94. As the first coil is completed the rope will engage the guiding depression 98 which shifts the rope toward the pulley side 92, FIG. 8, and out of alignment with the base surface 94 containing the first rope coil. Thus, it will be appreciated that the relationship shown in FIG. 8 occurs at the completion of the first revolution of pulley rotation during recoiling.
In view of the orientation shown in FIG. 8, at the beginning of the recoiling of the second coil in the pulley, the second coil of starter rope will lie upon the shoulder surface 96 as this shoulder surface now represents the innermost portion of the rope groove available for receiving the rope, and the first rope coil, shoulder surface 96 and pulley side 92 now define the rope receiving recess for the second coil.
At the completion of the winding of the second coil of rope within the pulley groove the rope passes over the portion of the second coil previously received within the rope guiding depression 98, and the third coil lies on top of the first rope coil received within the pulley base 94. The beginning of the coiling of the third coil is shown in FIG. 9 wherein the rope has passed over the initial rope portion received in depression 98.
In that the presence of the rope guiding depression 98 insures that the second coil will be wound upon the annular shoulder surface 96, and as the pulley groove configuration insures that the coil will be directly disposed over the supporting rope coil, binding of the rope within the pulley groove during engine cranking is prevented even though the tension occurring within the starter rope may be very high. Starters of the described type are of sufficient size such that the diameter of the rope pulley is great enough to permit three or four coils of starter rope to be wound thereon, and the rope pulley must be of sufficient diameter to permit sufficient torque to be applied to the engine flywheel for cranking.
The use of the plate type dog cam insures positive operation of the clutch dogs both during cranking and when retracted, and such operation is most important when employed with larger internal combustion engines which can easily destroy starter components if a malfunctioning occurs. Likewise, even though the cranking of larger sizes of engines with recoil starters requires high rope tensions the unique pulley configuration limiting the groove to two coils in an axial direction, in conjunction with the use of the base surface and shoulder surface, eliminates many of the problems heretofore encountered with recoil starters used with larger engines.
It is appreciated that modifications to the inventive concept may be apparent to those skilled in the art without departing from the spirit and scope thereof.