Abstract:
An arrangement for starting an engine includes a torque coupler provided between a starter motor and the engine crankshaft. The torque coupler includes a gear mechanism arranged to allow a starter motor to rotate for a period of time prior to transferring rotational torque to the crankshaft to turn the engine over.

Description:
FIELD OF THE INVENTION 
     The present invention relates to starter systems for motors, and more particularly, to an improved starter system operable to rapidly start a motor. 
     BACKGROUND OF THE INVENTION 
     Conventional engine systems commonly include a starter motor, a flywheel, and a vehicle engine. Responsive to operation of an ignition switch, the starter motor is operable to deliver a force directly to the flywheel of the engine to rotate the flywheel and start the engine. 
     While such systems adequately start a vehicle engine, they do not facilitate continual starting and stopping of the vehicle engine because the torque required by the starter motor to rotate the flywheel and start the engine cannot be rapidly generated. In this manner, conventional systems require vehicles to remain running when temporarily stopped such as at traffic lights and railroad crossings. 
     Further, while use of a larger starter motor may provide sufficient torque to rapidly and start a vehicle engine on demand, and may significantly reduce disparity in gear ration between the starter motor and flywheel, a larger starter motor typically creates packaging issues within an engine compartment of a vehicle. In addition, implementing a larger starter motor likely requires replacing a standard 12-volt vehicle battery/electrical system with a larger and more expensive 42-volt vehicle battery/electrical system to handle the electrical requirements of the larger starter motor. 
     Therefore, a need exists for a starter system arrangement that facilitates rapid and repeated starting (on-demand) of a vehicle engine when a vehicle is temporarily stopped. Additionally, such a starter system capable of operating with a conventional 12-volt vehicle battery is also desirable. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides an apparatus for improving engine starting wherein the apparatus includes a gearing arrangement in a torque transfer element arranged to momentarily delay driving of an output connected to an engine crankshaft, thereby allowing the torque transfer element to attain maximum rotation speed when driven by an engine starter motor before engine load is applied thereto. In this manner, the present invention provides a kinetic energy accumulator or “storage” arrangement in the torque transfer element operable to allow the output shaft of the starter motor to rotate up to speed for a predetermined period of time prior to transfer of rotational torque to the output. 
     In another aspect of the invention, a method for starting an engine is provided and includes providing a starter motor having an output shaft and a planetary gear set driven by the output shaft of the starter motor, rotating the starter motor to accumulate kinetic energy without concurrently driving an output of the planetary gear set, transferring the kinetic energy from the starter motor to the output of the planetary gear set once maximum or desired kinetic energy is achieved, such that the output of the planetary gear set is driven at a reduced rotational speed, and finally, fixing the output of the planetary gear set to a crankshaft of the engine and rotating the crankshaft in response to rotation of the output of the planetary gear set to thereby start the engine. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a sectional view of a starter system shown operably attached to a vehicle engine; 
         FIG. 2  is a perspective view of the starter system of  FIG. 1 ; 
         FIG. 3  is a side view of the starter system of  FIG. 1  in a first position; and 
         FIG. 4  is a side view of the starter system of  FIG. 1  in a second position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures, a starter system  10  for use with a vehicle engine  12  is provided and includes a starter motor  14  (in the exemplary embodiment the starter motor is arranged to operate in a conventional 12-volt vehicle electrical system), a torque coupler element including a planetary gear set  16 , and a pulley assembly  18 . The starter motor  14  is operable to rotate the planetary gear set  16  in response to an external signal. The planetary gear set  16  is operable to permit the starter motor  14  to accumulate sufficient kinetic energy prior to transmitting a rotational force to the pulley assembly  18  and vehicle engine  12 . In this manner, the planetary gear set  16  is operable to allow starter motor  14 , even if the vehicle electrical system is only a conventional 12-volt system, with the ability to build up a sufficient rotational force prior to engaging the pulley assembly  18  to ensure a sufficient torque is supplied to start the vehicle engine  12 , as will be discussed further below. 
     With reference to  FIG. 1 , the starter motor  14  is shown operably connected to the planetary gear set  16 . The starter motor  14  includes a main body  20  and an output shaft  22  extending therefrom. The main body  20  is operable to receive an external signal and rotate the output shaft  22  on demand. 
     A stop plate  24  is disposed between the main body  20  of the starter motor  14  and includes an elongate planar section  25  and a flared top section  27 . The planar section  25  extends generally along the length of the planetary gear set  16  and terminates at a base of the top section  27 , as best shown in  FIG. 2 . The top section  27  includes a first reaction surface  29  and a second reaction surface  31  for interaction with the planetary gear set  16 , as will be discussed further below. The stop plate  24  is fixed relative to the planetary gear seat  16  and the starter motor  14  to an external structure (not shown) such that as the planetary gear set  16  and output shaft  22  rotates, the stop plate  24  is held in position relative thereto. 
     The planetary gear set  16  includes a sun gear  26 , a plurality of pinion gears  28 , a ring gear  30 , and a planet carrier  32 . The sun gear  26  is splined for rotation with the output shaft  22  of the starter motor  14  and includes a series of helical teeth  34 . The pinion gears  28  include a series of helical teeth  36  which are in meshed engagement with the helical teeth  34  of the sun gear  26 . As best shown in  FIGS. 3 and 4 , the pinion gears  28  are axially disposed around the sun gear  26  such that movement of the helical teeth  36  relative to the helical teeth  34  causes the pinion gears  28  to rotate around the sun gear  26 . 
     The ring gear  30  axially surrounds the pinion gears  28  and includes an inner surface having a series of helical teeth  38  and a stop arm  40 . As best shown in  FIGS. 3 and 4 , the helical teeth  38  of the ring gear  30  are in meshed engagement with the helical teeth  36  of the pinion gears  28 . In this manner, as the helical teeth  36  of the pinion gears  28  move relative to the helical teeth  38  of the ring gear  30 , one of the pinion gears  28  or the ring gear  30  will rotate relative to the sun gear  26 , as will be discussed further below. The stop arm  40  extends from a first surface  42  of the ring gear  30  and includes a first engagement surface  44  and a second engagement surface  46 . The first engagement surface  44  is operable to selectively engage the first engagement surface  29  of the stop plate  24  while the second engagement surface  46  is operable to selectively engage the second engagement surface  31  of the stop plate  24 . While helical teeth are disclosed, it should be understood that any arrangement operable to transfer rotational force between the sun gear  26 , pinion gears  28 , and ring gear  30 , such as a frictional engagement, is anticipated and should be considered within the scope of the present invention. 
     The planet carrier  32  includes a main body  48 , a plurality of pinion shafts  50 , and a main shaft  52  extending therefrom. The pinion shafts  50  extend from a first face  54  of the main body  48  such that the pinion shafts  50  are rotatably received by each of the pinion gears  28  such that each pinion gear  28  is journally supported by the pinion shafts  50 . The main shaft  52  extends from a second face  56  of the main body  48  generally in an opposite direction to that of the pinion shafts  50 . 
     The main body  48  is journally supported by the output shaft  22  of the starter motor  14  such that rotation of the output shaft  22  will not cause rotation of the planet carrier  32 . Specifically, a bore  55  of the main body  48  receives the output shaft  22  generally at the first face  54 , as best shown in  FIG. 1 . In this manner, the planet carrier  32  may rotate relative to the output shaft  22  of the starter motor  14  and will rotate each of the pinion gears  28  concurrently as the planet carrier  32  is rotated relative to the output shaft  22 . As can be appreciated, the pinion gears  28  are operable to rotate the planet carrier  32  if a force is applied to the pinion gears  28  relative to the output shaft  22 . Alternatively, the planet carrier  32  is operable to rotate the pinion gears  28  relative to the output shaft  22  if a sufficient force is applied to the planet carrier  32 , as will be discussed further below. 
     The pulley assembly  18  is disposed between the planetary gear set  16  and the vehicle engine  12  and includes a first pulley  60 , a second pulley  62 , and a drive belt  64 . The first pulley  60  includes a central bore  66  and a reaction surface  68  axially surrounding an exterior surface  70  of the first pulley  60 . The main shaft  52  of the planet carrier  32  fixedly supports the first pulley  60 , whereby the central bore  66  of the first pulley  60  matingly receives the main shaft  52  of the planet carrier  32 . In this regard, rotation of either the planet carrier  32  or the first pulley  60  will cause rotation of the other of the planet carrier  32  and the first pulley  60 . 
     The second pulley  62  is substantially the same as the first pulley  60 . In this manner, a detailed description of the second pulley  62  is unnecessary. The second pulley  62  is fixedly attached to an input shaft  72  of the vehicle engine  12  at the central bore  66  and arranged to rotate therewith of the second pulley  62 . 
     The drive belt  64  is received by the exterior surfaces  70  of the first and second pulleys  60 ,  62  and engages the reaction surfaces  68  of each of the first and second pulleys  60 ,  62 . As can be appreciated, movement of the drive belt  64  along the reaction surfaces  68  of the first and second pulleys  60 ,  62  causes the first and second pulleys  60 ,  62  to concurrently rotate. In this manner, a force applied to one of the first and second pulleys  60 ,  62  will cause the other of the first and second pulleys  60 ,  62  to rotate as the force will be transmitted along the drive belt  64  between the first and second pulleys  60 ,  62 . It should be understood that while a drive belt  64  is disclosed, any suitable load transfer element such as a drive chain and the like, is anticipated and should be considered within the scope of the present invention. 
     In addition to a belt driven system, it is will be understood that the planetary gear set  16  of the present invention could also be used in a direct in-line coupling arrangement. Specifically, the planetary gear set  16  could be directly coupled to the input shaft  72  of the vehicle engine  12  via main shaft  52  of planet carrier  32 . 
     With reference to the figures, the operation of the starter system  10  will be described in detail. As previously discussed, the starter system  10  is operable to rotate an input shaft of a vehicle engine  12  in order to start the engine. To begin the start sequence, an external signal is sent to the starter motor  14 , thereby causing the starter motor  14  to rotate output shaft  22  at a predetermined speed. Rotation of the output shaft  22  concurrently causes rotation of the sun gear  26  as the sun gear  26  is fixed for rotation with the output shaft  22 . 
     As the sun gear  26  rotates relative to the main body  20  of the starter motor  14 , the pinion gears  28  transfer the rotational motion from the sun gear  26  to the ring gear  30 , thereby causing the ring gear  30  to rotate relative to the main body  20  of the starter motor  14 . At this point, the pinion gears  28  simply transfer the rotational force from the sun gear  26  to the ring gear  30  and do not rotate relative to the main body  20 . In an exemplary embodiment, the sun gear  26  and ring gear  30  can have a gear ratio of approximately  3 : 1  such that for every three rotations of the sun gear  26 , the ring gear rotates one time. In this regard, the sun gear  26  freely rotates relative to the main body  20  of the starter motor  14  without transferring any rotational forces to the planet carrier  32 , pulley system  18 , or the vehicle engine  12 , thereby allowing the sun gear  26  to build up kinetic energy prior to engaging the planet carrier  32 . 
     Sufficient rotation of the ring gear  30  will cause the first engagement surface  44  of the stop arm  40  to contact the first reaction surface  29  of the stop plate  24 , thereby restricting further rotation of the ring gear  30 . As the ring gear  30  is abruptly stopped against the stop arm  40 , the pinion gears  28  are caused to instantaneously rotate relative to the ring gear  30  due to the built-up kinetic energy of the rotating output shaft  22  and sun gear  26 . In this regard, the pinion gears  28  will initially rotate with a great deal of force, thereby causing the planet carrier  32  to rotate at a high speed and with a large amount of torque. 
     As previously discussed, rotation of the planet carrier  32  causes concurrent rotation of the first pulley  60 . Once the first pulley  60  begins to rotate, the rotational forces  60  exerted thereon are transferred to the second pulley  62  and input shaft  72  of the engine  12  via the drive belt  64 . The rotational force exerted on input shaft  72  is large enough to rapidly turn the input shaft  72 , thereby causing the engine  12  to fire and start very quickly due to the build up kinetic energy of the freely spinning sun gear  26  and the rapid transfer of this energy to the planet carrier  32 . 
     As the engine  12  begins to rotate, the input shaft  72  will build up speed to a point where it is rotating at a much faster rate than the output shaft  22  of the starter motor  14 . At this point, power to the output shaft  22  of the starter motor  14  is stopped, thereby causing the sun gear  26  to impart a force on the pinion gear  28  and restrict further rotation of the output shaft  22 . As can be appreciated, such restriction by the sun gear  26  causes the ring gear  30  to disengage the stop arm  40  and rotate such that the first engagement surface  44  disengages the first reaction surface  29 . Such rotation of the ring gear  30  is accomplished by the rotation of the pinion gears  28  relative to the sun gear  26 . 
     As the ring gear  30  rotates away from engagement with the first reaction surface  29  of the stop arm  40 , the second engagement surface  46  approaches the second reaction surface  31  of the stop arm  40 . Once the ring gear  30  has sufficiently rotated away from the first reaction surface  29 , the second engagement surface  46  will contact the second reaction surface  31  of the stop arm  40 , thereby restricting further rotation of the ring gear  30 , as best shown in  FIG. 4 . At this point, the rotation of the planet carrier  32  will still cause rotation of the pinion gears  28  relative to the ring gear  30 . As previously discussed, the pinion gears  28  are in meshed engagement with the sun gear  26  and ring gear  30 , and as such, rotation of the pinion gears  28  relative to the ring gear  30  cause concurrent rotation of the sun gear  26 . In this manner, the engine  12  is operable to drive the output shaft  22  of the starter motor  14  at very high speeds without damaging the gearing of the planetary gear set  16 . As the engine  12  rotates the output shaft  22 , the starter motor  14  begins to act as an alternator, thereby generating electricity for use with other components associated with the vehicle (not shown). 
     As described, the starter system  10  of the present invention allows for the engine  12  to be stopped repeatedly, such as at traffic lights and the like, and is operable to be quickly started when movement of a vehicle is desired. In this regard, fuel can be conserved. In addition, the starter system  10  of the present invention concurrently provides a starter motor  14  with the ability to act as an alternator in response to the vehicle engine  12  rotating the output shaft  22  of the starter motor  14  at high speeds. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.