Patent Publication Number: US-6655336-B2

Title: Hand-held starting device for model engines

Description:
This patent application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application Ser. No. 60/208,143, filed May 31, 2000, which is expressly incorporated by reference herein. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to engine starters, and particularly to starters for model engines. More particularly, the present invention relates to hand-held starters for model engines used in model helicopters, airplanes and cars. 
     Model engines, such as those commonly used on model airplanes, typically do not include an automatic starting feature, but are sometimes started by hand. Manual starting requires a skilled operator, and is often difficult if the model engine is not properly adjusted. Hand-held electric starter motors are now in widespread use and make starting a model engine much easier. These devices typically consist of a high-torque electric motor held in the palm of the operator&#39;s hand and actuated by a finger switch. Such devices are applied to an output shaft of the model engine to turn the model engine at high speed while the operator performs appropriate engine starting procedures. Once the model engine is running, the electric starter motor is disconnected from the engine and set aside. 
     The minimum amount of torque that a starter motor must produce to start a model engine is generally dictated by the size of the model engine with which the starter motor is used. Traditional hand-held starters are bulky and cumbersome, partly because they are sized to start large model engines, and partly because the finger switch of these starters is commonly located on the motor housing itself thereby increasing the effective diameter of the motor and the associated hand-grip diameter. Large diameter starters are not well suited for use by operators with small hands such as children or teenagers. 
     Most commercially available starters are designed to start model engines of 0.10 cubic inch displacement to 0.60 cubic inch displacement and are called “standard” or “medium” starters. Starters capable of starting up to about 1.5 cubic inch displacement engines are termed “high torque” starters. Medium and high torque starters generally operate at relatively low rotational speeds of between 3000 revolutions per minute (RPM) and 6000 RPM, which is too slow to easily start small model engines below 0.10 cubic inch displacement. Such small model engines start more easily when turned at a high speed of 10,000 RPM to 15,000 RPM. 
     As populations increase and recreational sites become scarce, smaller models and model engines are becoming more popular. These small models are suitable for younger modelers who have small hands and who cannot comfortably operate a large electric starter. What is needed is a hand-held starting device suitable for small engines and adapted for use by operators with small hands as well as by operators with large hands. 
     According to the present disclosure, a hand-held starter apparatus for starting model engines includes a motor, a body supporting the motor, a switching device that activates the motor, and a trigger in communication with the switching device. The body is configured for comfortable gripping by users with large hands and by users with small hands. 
     In preferred embodiments, the motor is a high-speed starter motor having a shaft that rotates about a motor rotation axis and having an adapter assembly that is coupled to the shaft and that is configured to couple to an engine shaft of a model engine to transfer rotational motion from the starter motor to the model engine. In an illustrative embodiment, the body has a front portion which is generally circular in cross-section near the starter motor and a rear portion which is generally elliptical or oval in cross-section to more comfortably accommodate the small (“ring” and “pinky”) fingers of the operator&#39;s hand. The trigger switch is preferably located behind the starter motor to minimize the diameter of the body adjacent to the starter motor. The trigger extends from the body in a forward direction over the motor and is actuated by the fingers or palm of the operator&#39;s hand. 
     According to this disclosure, the body includes a forward ridge and a rear ridge to axially position the operator&#39;s hand during operation of the hand-held starter apparatus. A front guard is provided to protect against accidental finger injury during starting of a model engine and to prevent accidental depression of the trigger when the hand-held starter apparatus is placed on a hard, flat surface such as the ground or a table after use. 
     In contrast to existing hand-held industrial motors such as electric and air powered die grinders which are generally cylindrical, the illustrative body narrows and is configured to accommodate the small fingers of the hand and support the hand grip of the operator against axial force, such as the force required to hold the starter motor against a shaft of a model engine during starting. The illustrative body is suitable for use in a vertical orientation where the axial holding features of the body provide a positive hand-hold against gravity even when the exterior of the device is coated with slippery engine exhaust oil from a model engine. 
     When equipped with a high-speed 10,000 RPM to 15,000 RPM motor, the starter apparatus of the present disclosure is ideally suited to start small engines of less than 0.10 cubic inch displacement. Furthermore, the illustrative apparatus is small and maneuverable enough to be used as a hobby tool in addition to a model engine starter, and an adapter is provided to accommodate commercially available rotary cutting and grinding tools. An alternative portable embodiment having an on-board battery is also shown and described in this disclosure. 
     This disclosure, therefore, relates to a hand-held starting device for model engines, and particularly, to a hand-held starter motor that can be rotationally coupled to a model internal combustion engine to impart rotational motion to the model engine to induce the model engine to start and continue operating under its own power. The illustrative apparatus is suitable for starting model airplane, car, helicopter, and boat engines and is configured to be operated by operators whose hands are generally smaller than those of adults. Thus, the disclosed apparatus is uniquely configured to accommodate small hands safely and comfortably. The disclosed apparatus alternatively can be configured to operate as a portable rotary hand-tool. 
    
    
     Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The detailed description particularly refers to the accompanying figures in which: 
     FIG. 1 is a side elevation view of a hand-held starter apparatus in accordance with the disclosure showing a body that is configured to be hand held, the body including a pair of downwardly extending ridges between which is defined a finger-receiving space, an adapter assembly to the left of the body, a trigger having portions located above the body, and a front guard extending upwardly from a front end of the body between the trigger and the adapter assembly; 
     FIG. 2 is a top plan view of the hand-held starter apparatus of FIG. 1 showing the body being formed to include curved side profiles; 
     FIG. 3 is a rear elevation view of the starter apparatus of FIG. 2 showing that a rear portion of the body is oval in cross section and showing that a front portion of the body is circular in cross section; 
     FIG. 4 is a cross sectional view of the starter apparatus of FIG. 1 showing a motor situated in an interior region of the body adjacent the front end of the body, the motor including a shaft to which the adapter assembly couples, a switch situated in the interior region between the motor and a rear end of the body, and the trigger including portions in the interior region of the body that interact with the switch; 
     FIG. 5 is a side elevation view similar to FIG. 1 showing the relative positions of a plurality of planes (labeled A-F) through which cross sections are taken to show the variations in shape of an outer surface of the body between the front end and the rear end of the body; 
     FIG. 6 is a cross sectional view taken along plane A of FIG. 5 showing the outer surface having a substantially circular shape adjacent the front end of the body; 
     FIG. 7 is a cross sectional view taken along plane B of FIG. 5 showing the outer surface having a somewhat circular shape, but slightly out of round, at a middle region of the body that is closer to the front end than the rear end; 
     FIG. 8 is a cross sectional view taken along plane C of FIG. 5 showing the outer surface having a slightly elliptical or oval shape at a middle region of the body that is closer to the rear end than the front end; 
     FIG. 9 is a cross sectional view taken along plane D of FIG. 5 showing the outer surface having a substantially elliptical or oval shape at a region of the body that is closer to the rear end than the region of the body shown in FIG. 8; 
     FIG. 10 is a cross sectional view taken along plane E of FIG. 5 showing the outer surface having a substantially elliptical or oval shape at a region of the body that is closer to the rear end than the region of the body shown in FIG. 9; 
     FIG. 11 is a cross sectional view taken along plane F of FIG. 5 showing the outer surface having a substantially elliptical or oval shape adjacent the rear end of the body; 
     FIG. 12 is a side elevation view similar to FIG. 1 showing an operator holding the body of the starter apparatus with a standard grip and orienting the starter apparatus in a position having the adapter assembly in alignment with a propeller spinner of a model airplane; 
     FIG. 13 is a side elevation view similar to FIG. 12 showing the operator holding the body of the starter apparatus with an alternative grip; 
     FIG. 14 is a side elevation view similar to FIG. 13 showing the operator holding the body of the starter apparatus with a relaxed grip; 
     FIG. 15 is a side elevation view similar to FIG. 14 showing the operator holding the body of the starter apparatus with an extended grip; 
     FIG. 16 is a side elevation view similar to FIG. 15 showing the starter apparatus in a vertical orientation and showing the operator holding the body of the starter apparatus with a palm grip; 
     FIG. 17 is a diagrammatic view of a palm and fingers of a large hand showing the width of the large hand across the palm; 
     FIG. 18 is a diagrammatic view of a palm and fingers of a small hand showing the width of the small hand across the palm; 
     FIG. 19 is a side elevation view of a first side of a prior art electric starter showing the prior art starter motor having a large outside diameter and showing an operator with small hands holding the prior art starter motor; 
     FIG. 20 is a side elevation view of a second side of the prior art electric starter of FIG. 19; 
     FIG. 21 is a side elevation view similar to FIG. 12 showing an operator having small hands holding the preferred starter apparatus with the standard grip; 
     FIG. 22 is a side elevation view similar to FIG. 21 showing the operator having small hands holding the starter apparatus with the alternative grip; 
     FIG. 23 is a perspective view of the starter apparatus of FIG. 1 showing a rotary cutting tool coupled to the adapter assembly; 
     FIG. 24 is a side elevation view of a hand-held starter apparatus in accordance with an alternative embodiment showing a power pack coupled to the body of the alternative embodiment by a front brace and by a rear electric-wire conduit and showing a battery pack (in phantom) carried by the power pack; and 
     FIG. 25 is a side elevation view of an alternative embodiment of a hand-held starter apparatus showing a trigger coupled to a body and extending from the body adjacent a front ridge of the body. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to FIGS. 1,  2 ,  3 ,  4  and  12 , a hand-held starting device or starter apparatus  10  is shown to scale in the drawings and comprises a starter motor  12  having shaft  11  that rotates about a motor rotation axis  14 , a body  16  adapted to support starter motor  12  and accommodate a variety of sizes of hands  15 , a trigger  18  in the form of a trigger lever in communication with a switch  20  to actuate starter motor  12 , adapter hub assembly  23  having an adapter hub  22  connected to starter motor  12  and a coupling adapter  24  connected to adapter hub  22 , said coupling adapter  24  adapted to couple starter motor  12  to shaft  26  of a model engine  28  to transfer rotational motion from shaft  11  of starter motor  12  to model engine  28 . In a preferred embodiment, coupling adapter  24  is made of an elastomeric material such as rubber or silicone that conforms to the shape of an end-receptor of model engine shaft  26  such as propeller spinner  27  on a model airplane (not shown). 
     Wires  21  connect switch  20  and motor  12  to a power supply such as a 12 volt battery (not shown). In a preferred embodiment, starter motor  12  is a model no. SJ550 electric motor which is available from Hankscraft Motors of Reedsburg, Wis., and which is configured with windings for 15,000 RPM at 6 or 12 volts (depending upon the power source). Similar motors are commonly available for use in radio-controlled cars and may be used in lieu of the preferred motor to provide starter apparatus  10  with desired torque or RPM characteristics. 
     Trigger switch  20  is preferably located behind starter motor  12  to minimize the diameter of forward body portion  30  adjacent to starter motor  20 . Trigger  18  pivots about trigger pivot  19  and is automatically restored to an “off” position by a trigger spring  17 . Trigger  18  generally extends from pivot  19  over starter motor  12  in a forward direction. Trigger  20  is configured to be actuated by the thumb  34  or palm  36  of the operator&#39;s hand. Depression of trigger  18  as by thumb  34  actuates button  13  on switch  20  and applies power to starter motor  12  to activate motor  12  causing shaft  11  to rotate about axis  14 . Trigger  18  is curved upward with a radius of curvature  33  of about 3.5 inches to follow the natural curvature of lower surface  35  of thumb  34 . Trigger pivot  19  is preferably located in rear body portion  32  to take advantage of the most natural hand motion to actuate trigger  18 . Alternative embodiments, as shown for instance in FIG. 25, wherein a trigger in the form of a trigger button  111  is situated adjacent to or along front edge  52  of front ridge  54  to be actuated by finger  51  are within the scope of this disclosure. 
     Body  16  includes a forward body portion  30  which is generally circular in cross-section adjacent to starter motor  12  and a rear body portion  32  which is generally elliptical or oval in cross-section to accommodate the small fingers of the operator&#39;s hand. Forward portion  30  and rear body portion  32  blend together smoothly and thus, cooperate to provide body  16  with a main portion  30 ,  32  that extends between a front end  48  and a rear end  49  of body  16 . Top profile  45 , bottom profile  46  (FIG. 1) and side profiles  43 ,  44  (FIG. 2) of main portion  30 ,  32  are generally smoothly contoured to comfortably receive the operator&#39;s hand. As shown in FIG. 3, top profile  45  and bottom profile  46  blend smoothly into side profiles  43 ,  44  to comfortably receive the operator&#39;s hand. 
     Referring now to FIGS. 5-11, the shape of body  16  and profiles  43 ,  44 ,  45 , and  46  are defined by cross sections taken along planes A-F that are each perpendicular to axis  14 . Distance  75  between plane A and plane B is about 2.5 inches. Distance  76  between plane B and plane C, distance  77  between plane C and plane D, distance  78  between plane D and plane E, and distance  79  between plane E and plane F are all about 0.8 inches. When the word “about” is used in connection with any distance or dimension in the specification and in the claims, it is intended that a distance or dimension in a range of plus or minus 20 percent of the cited amount, (or an amount approximately equal to the size difference between a young female hand and an adult male hand), is covered literally, unless specifically noted otherwise. Thus, for example, the phrase “about 1 inch” literally covers distances or dimensions in the range of 0.8 inches to 1.2 inches and the phrase “about 4 inches” literally covers distances or dimensions in the range of 3.2 inches to 4.8 inches. Other ranges are intended to be covered equivalently, unless specifically noted otherwise. 
     Cross section A at front end  48  of body  16  is circular with height  56  of about 1.6 inches, width  57  of about 1.6 inches, and area of about 1.95 square inches. Cross sections B through E, are generally elliptical with cross section E being narrower than cross section B. Cross section B has height  60  of about 1.69 inches, width  61  of about 1.62 inches, and area of about 2.07 square inches. Cross section C has height  63  of about 1.65 inches, width  64  of about 1.47 inches, and area of about 1.46 square inches. Cross section D has height  66  of about 1.56 inches, width  67  of about 1.26 inches, and area of about 1.48 square inches. Cross section E has height  69  of about 1.43 inches, width  70  of about 1.0 inch, and area of about 1.10 square inches. Cross section F has height  72  of about 1.26 inches, width  73  of about 0.8 inches, and area of about 0.78 square inches. 
     The cross-sectional areas of cross sections E and F are only about one-half (53%) and one-third (38%), respectively, of the area of cross section B. The lower cross-sectional areas of sections C through F, and their smaller radiuses of curvature along bottom profile  46  accommodates the small (“pinky”) and ring fingers of the operator&#39;s hand more comfortably and securely than conventional hand-held starters. 
     Main body portion  30 ,  32  is elongated and extends along a body axis that in some embodiments is parallel with axis  14  and that in the illustrative embodiment is coaxial with axis  14 . Thus, in the illustrative embodiment, heights  56 ,  60 ,  63 ,  66 ,  69 ,  72  intersect the respective widths  57 ,  61 ,  64 ,  67 ,  70 ,  73  at axis  14 . 
     Body  16  includes front ridge  54  and rear ridge  55  to axially position and support the operator&#39;s hand during operation of the electric starter. Front ridge  54  and rear ridge  55  are spaced apart to accommodate various hand sizes and hand grip configurations as discussed in detail below. Thus, a finger-receiving space is defined between front ridge  54  and rear ridge  55 . 
     As shown in FIG. 1, a front portion  52  of front ridge  54  blends smoothly from a distal tip thereof into body portion  30  and is defined by a front arc having a forward face radius  82  of about 0.8 inches. A rear portion  85  of front ridge  54  blends smoothly from the distal tip thereof into body portion  30  and is defined by a second arc having a rear face radius  83  of about 0.39 inches. The center of the front arc from which radius  82  originates is forward of ridge  54  and the center of the second arc from which radius  83  originates is rearward of ridge  54 . The centers from which radii  82 ,  83  originate are separated by an interfinger distance  84  of about 1.3 inches. Front ridge  54  is wide and deep enough to comfortably support a large portion of the pointer and index fingers of the operator&#39;s hand, and has a front ridge width  89  of about 1.66 inches and front ridge depth  90  of about 0.57 inches as shown in FIG.  3 . 
     A front portion  87  of rear ridge  55  blends smoothly from a distal tip thereof into body portion  32  and is defined by an arc having a front face radius  86  of about 0.6 inches as shown in FIG.  1 . The distal tip of rear ridge  55  is spaced apart from the distal tip of front ridge  54  by a ridge spacing  92  of about 4.1 inches. Rear ridge  55  preferably has a rear ridge depth  93  of about 0.51 inches. Rear ridge depth  93  can be extended to about 0.8 inches to provide greater support if desired. 
     As shown, for example, in FIGS. 4 and 5, body  16  includes a front guard  38  that extends away from body portion  30  adjacent front end  48  of body  16 . A distal tip  17  of trigger  18  is spaced apart from and confronts front guard  38 . Thus, front guard  38  is positioned to lie between adapter assembly  23  and trigger  18  to act as a shield that prevents thumb  34  from extending or slipping in front of body  16  thereby reducing the possibility that thumb  34  will come into contact with model engine  28  or anything attached thereto such as propeller  29  of a model airplane (not shown). Tip  39  of front guard  38  and rear top corner  40  of body  16  form roll line  41  as shown in FIG.  4 . Roll line  41  is, at all points, above trigger  18  thereby preventing accidental depression of trigger  18  if starter apparatus  10  is placed on or rolled on the ground or other hard, flat surface after use. 
     The small size, unique cross sections and special front ridge  54  and rear ridge  55  of starter apparatus  10  support a variety of hand grip configurations as shown in FIG.  12  through FIG.  16 . Hand grip configurations are described herein as “standard”, “alternative”, “relaxed”, “extended” and “palm” depending upon the finger configuration of the grip. Other grip configurations are possible, but are not shown. 
     FIG. 12 shows standard grip  98  having large hand  15  axially positioned by front ridge  54  between pointer finger  51  and index finger  53 . Standard grip  98  provides great forward thrust capability. Tapered rear portion  32  of body  16  allows ring finger  58  and small finger  59  to close on body  16  more than pointer finger  51  and index finger  53 , and improves the ability of the operator to apply axial force in direction  96  to body  16  without hand  15  slipping axially. Thumb  34  rests comfortably against trigger  18  with little or no force thereby reducing the possibility of accidental operation of trigger  18 . 
     Alternative grip  99  shown in FIG. 13 has fingers  51 ,  53 ,  58  and  59  positioned between front ridge  54  and rear ridge  55 . Ring finger  58  and small finger  59  can close more completely around rear body portion  32  which is more comfortable for some operators. 
     Relaxed grip  100  is shown in FIG. 14 where large hand  15  is again axially positioned by front ridge  54  between pointer finger  51  and index finger  53  of large hand  15 , but without ring finger  58  or small finger  59  engaging body  16 . Relaxed grip  99  provides delicate control of axial force which can, for instance, reduce the possibly of damage to model airplanes (not shown) which must be lightly constructed to fly well. 
     Extended grip  101  is shown in FIG. 15 where operation of starter  10  is extended by hand  15  gripping rear portion of body  32  with rear ridge  55  situated between ring finger  58  and little finger  59 . Rear ridge  55  prevents hand  15  from slipping axially along body  16 . Trigger  18  is long enough to be actuated by thumb  34  even in the extended position. Extended grip  101  is advantageous, for instance, in applications where the engine being started is obstructed by a portion of the model such as in model helicopter applications where the engine is embedded deeply within the model helicopter fuselage (not shown). 
     Palm grip  102  is shown in FIG. 16 where trigger  16  is being actuated by palm  36  of hand  15 . Front ridge  54  prevents starter apparatus  10  from slipping axially out of hand  15 . Palm grip  102  allows the operator&#39;s arm (not shown) to comfortably extend at a right angle to axis  14  of starter motor  12  when starting a model airplane which is sitting on the ground while simultaneously holding the model airplane with the other hand. 
     As illustrated in FIGS. 13-16, front ridge  54  and rear ridge  55  cooperate to form a finger-receiving space which receives one or more of the operator&#39;s fingers. Thus, ridges  54 ,  55  facilitate the axial positioning of the operator&#39;s hand  15  and also serve to support hand  15  in the standard configuration, shown in FIG. 13, and in the alternative grip configurations, shown in FIGS. 14-16. In addition, front ridge  54  and rear ridge  55  each cooperate independently with trigger  18  to allow various hand grip configurations without impairing the triggering function of starter apparatus  10 . 
     Body  16  of starter apparatus  10  is designed to accommodate hands of varying sizes. FIG. 17 illustrates the size of large hand  15  which has a large hand width  112  of about 3.8 inches (adult male) and FIG. 18 illustrates a small hand  108  which has a small hand width  113  of about 2.8 inches (young female). The young female hand  108  is roughly 40% smaller than the adult male hand. 
     FIGS. 19 and 20 show a commercially available Sullivan-brand electric starter  116  model “600 Hi-Tork” having a cylindrical body  117 , front cap  118 , hand rest  119 , adapter hub  120  and elastomeric coupling adapter  121  and held by small hand  108 . The large diameter of body  117  prevents the operator from completely closing fingers  109  on body  117  so fingers  109  must support starter  116  through trigger  122 . This can be awkward and can result in accidental operation of trigger  122 . Axial loads are carried by hand rest  119  on front cap  118  situated between thumb  110  and fingers  109 . 
     In contrast, FIGS. 21 and 22 show small hand  108  comfortably gripping starter apparatus  10 . Fingers  109  can close more completely on body  16  than can the same fingers on motor case  117  of starter  116  shown in FIGS. 19 and 20. Thus, the shape of body  16  is configured so that a user having small hands is able to grip starter apparatus  10  more firmly and more comfortably than the user is able to grip prior art starter  116 . 
     Referring now to FIG. 23, a tool chuck adapter  125  is coupled to adapter hub  22  in place of coupling adapter  24 . A saw blade  126  is coupled to tool chuck adapter  125  to rotate therewith. Other types of tools such as grinders, reamers, deburrers, and the like may be coupled to tool chuck adapter  125  in lieu of saw blade  126 . Thus, a variety of tools may be coupled to starter apparatus  10 . Such tools may be of the type suitable for general maintenance of a model at a flying field or model park where the a model is being operated. The dual use of apparatus  10  as a starter and as a hand tool allows the operator to perform maintenance away from home without bringing extra power tools or source of power to the model park. 
     Adapter hub  22  is adapted to receive and securely hold tool chuck adapter  125 . In a preferred embodiment, tool chuck adapter  125  is retained by adapted hub  22  by use of a snap fit connection between tool chuck adapter  125  and adapter hub  22  so that tool chuck adapter  125  may be inserted and removed from adapter hub  22  by hand without the need to use other tools. 
     Starter apparatus  10  may be powered in many ways including by electric power as from a battery. Battery connections can be made by long wires  21  to the terminals of a power cell such as a 12 volt automobile battery (not shown). An alternative embodiment starter apparatus  128  is shown in FIG.  24 . Portable starter  128  includes a power pack  129  supported below body  16  by a forward battery brace  131  appended to front end  48  of body  16  and by a rear electric-wire conduit  132  appended to rear body portion  32 . Power pack  129  houses a widely available six-cell, 7.2 volt NiCad or nickel metal hydride battery pack  134  or similar battery packs commonly used in radio-controlled cars. Wires (not shown) extend through conduit  132  to supply motor  12  with power from battery pack  134 . Thus, starter apparatus  128  is portable and self-contained allowing the operator greater freedom of motion than do embodiments with long battery wires that couple to remote sources of power. 
     In alternative embodiments (not shown), rear end  49  of body  16  is extended rearwardly along axis  14  to accommodate and enclose a battery power pack, such as power pack  129 , instead of supporting power pack  129  below body  16  in the manner shown in FIG.  24 . Such alternative embodiments are easier to hold in a vertical orientation (with axis  14  vertical to the ground) when starting a model helicopter engine such as the engine of a Model 110 helicopter manufactured by Lite Machines Corporation of West Lafayette, Ind. 
     Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.