Abstract:
An improved shift mechanism for a marine propulsion transmission is provided. The shift mechanism includes a guide that defines a slot that receives a member of a linkage that connects an operator unit with a shift rod. Movement of the shift mechanism is converted into substantially linear motion and a shift position sensor is located at a substantially right angle to that movement. Information from the sensor is transmitted to a control unit and is employed to prevent abrupt starts. The shift position sensor is located on the side of an engine for ease of assembly and maintenance. Movement of the shift mechanism may also cause pivotal movement of the guide and this pivotal movement may be employed to reduce the engine speed and assist shifting.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a marine propulsion system and, in particular, to an improved shifting mechanism. 
     2. Background of the Invention 
     Some conventional outboards motor include the following basic components: an engine, a crankshaft, a power transmission, a propeller, and a shifting mechanism. The engine may be contained within a protective cowling that includes an upper cover and a lower tray. Extending below the tray is a drive shaft housing that supports the engine and houses the drive shaft. Below the drive shaft housing is a lower unit that carries the transmission and the propeller. The transmission is located inside the lower unit and transmits power from the drive shaft to the propeller. Rotation of a shift rod, which depends into the transmission, shifts the transmission between gears. 
     The shift rod may be controlled by an operator. For instance, an actuator controlled by the operator may be coupled together with the shift mechanism and a shift lever. The shift lever, in turn, may be coupled to the shift rod such that circular rotation of the shift lever rotates the shift rod. Thus, the watercraft operator uses the actuator and the shift mechanism to selectively determine the gear of the transmission. 
     Shift mechanisms often include a shift position detection sensor to detect the circular motion of the shift lever. The sensor may be used to determine when the shift lever is in the neutral position. In such instances, the engine may be designed to start only when it receives a signal from the shift position sensor that the shift lever is in a neutral position. This helps to reduce abrupt movement upon ignition start-up. In addition, as disclosed in U.S. Pat. No. 5,050,461, the shift mechanism may also be configured to temporarily reduce the engine speed during shifting. This type of engine control aids shifting between gears. 
     SUMMARY OF THE INVENTION 
     Earlier shift mechanisms, however, suffer from several drawbacks. For example, the shift position sensor may be located in a space within the lower tray, between the engine and the drive shaft housing. This space is very narrow, making assembly and maintenance of the shift position detection sensor difficult. Furthermore, the recent trend in the industry is to reduce the size of the outboard motor by compacting the cowling. This exacerbates the cramped space in the lower tray. Therefore, there is a need to reduce the size and complexity of the shift mechanism and to reposition the shift mechanism such that it can be assembled and maintained easier. 
     In addition, the shift position sensor is preferably positioned at a right-angle relative to the motion of the shift lever in order to detect more accurately the position of the shift lever. However, due to the arcuate paths of many shift levers, properly configuring such a right-angle relationship has proven difficult. 
     Thus, one object of the present invention is to overcome some or all of the aforementioned limitations of the prior art and to provide an improved shift control mechanism 
     Accordingly, one aspect of the present invention involves a marine propulsion system comprising a transmission with at least two operating states. A shift mechanism is coupled to the transmission and establishes the operating state of the transmission. The shift mechanism moves between at least a first shift position and a second shift position with the first shift position corresponding to the first operating state of the transmission and the second shift position corresponding to the second operating state of the transmission. An operator unit is disposed remotely relative to the shift mechanism and is adapted to move between at least a first and second control position. The operator unit is coupled to the shift mechanism such that movement of the operator unit to the first control position positions the shift mechanism in the first shift position, and movement of the operator unit to the second control position positions the shift mechanism in the second shift position. The shift mechanism includes a member that moves along a substantially linear path. A shift position sensor is arranged to cooperate with the member so as to detect at least one of the shift positions. 
     Another aspect of the present invention involves a marine propulsion system comprising an engine and a transmission that is coupled to the engine and has at least two operating states. A shift mechanism is coupled to the transmission and establishes the operating state of the transmission. The shift mechanism is capable of moving between at least a first shift position and a second shift position with the first shift position corresponding to the first operating state of the transmission and the second shift position corresponding to the second operating state of the transmission. An operator unit is disposed remotely relative to the shift mechanism. The operator unit is adapted to move between at least first and second control positions and is coupled to the shift mechanism. Movement of the operator unit to the first control position positions the shift mechanism in the first shift position, and movement of the operator unit to the second control position positions the shift mechanism in the second shift position. A shift position sensor is arranged to detect at least one of the shift positions. The sensor is arranged on a side of the engine and to an outer side of the shift mechanism. 
     For purposes of summarizing the invention and the advantages achieved over the prior art, certain features, aspects, objects and advantages of the invention have been described above. Of course, none of these features, aspects, objects or advantages should be considered essential. Also, any one embodiment of the present invention may employ one or more of these features, aspects, objects or advantages. Thus, for example, those of ordinary skill in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other features, aspects, objects or advantages, as may be taught or suggested herein. 
     All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Having thus summarized the general nature of the invention and some of its features, aspects, objects, and advantages, certain preferred embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which: 
     FIG. 1 is a side elevation view of an outboard motor constructed in accordance with an embodiment of the invention; 
     FIG. 2 is a partially sectioned top plan view showing a shifting mechanism configured with certain features, aspects, and advantages of the present invention; 
     FIG. 3 is a partially sectioned side elevation view of the shifting mechanism shown in FIG. 2 taken along line  3 — 3 ; 
     FIG. 4 is a partially sectioned top plan view of the shifting mechanism shown in FIG. 2, with portions removed, and showing the mechanism in a neutral drive position; 
     FIG. 5 is a partially sectioned top plan view of the shifting mechanism shown in FIG. 2, with portions removed, and showing the mechanism in a reverse drive position; 
     FIG. 6 is a schematic top view of the engine and the shifting mechanism shown in FIG. 2, with a cowling outline shown in phantom lines; 
     FIG. 7 is a partially sectioned top plan view showing another shifting mechanism, configured in accordance with certain features aspects and advantages of the present invention; 
     FIG. 8 partially sectioned side elevation view of the shifting mechanism shown in FIG. 7 taken along line  8 — 8 ; 
     FIG. 9 is a partially sectioned top plan view of the shifting mechanism shown in FIG. 7, with portions removed, and showing the mechanism in a neutral drive position; 
     FIG. 10 is a partially sectioned top plan view of the shifting mechanism shown in FIG. 7, with portions removed, and showing the mechanism in a reverse drive position; 
     FIG. 11 is a schematic top plan view of the engine with a cowling outline shown in phantom lines and another shifting mechanism configured in accordance with certain features aspects and advantages of the present invention; and 
     FIG. 12 is a more detailed top plan view of the shifting mechanism shown in FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 depicts an outboard motor  10  constructed in accordance with certain features, aspects, and advantages of the present invention. While the present invention is described in conjunction with an outboard motor, those of ordinary skill in the art will appreciate that the invention may be used in other applications. 
     The outboard motor  10  has a powerhead  11  which includes an internal combustion engine  14 . A protective cowling  12  surrounds the engine  14 . The cowling  12  includes a lower tray  16 . The tray  16  and the cowling  12  together define a compartment which houses the engine  14  with the lower tray  16  encircling a lower part of the engine  14 . 
     The motor  10  is moveably mounted to a hull  22  of the watercraft  8 . Preferably, a steering shaft  24  is connected to the motor  10 . The steering shaft  24  is supported for steering movement about a vertically extending axis (not shown) within a swivel bracket  26 . This mounting permits the watercraft to be steered by turning the motor  10  about the vertically extending axis that passes through the swivel bracket  26 . 
     The swivel bracket  26  is connected to a clamping bracket  28 . The clamping bracket enables movement of the motor  10  about a generally horizontally extending pin  30 . The clamping bracket  28  is connected to the hull  22  of the watercraft. The mounting about the pin  30  permits the motor  10  to be trimmed or tilted up and down with respect to the water  31  in a vertical plane about a horizontal axis extending through the pin  30 . 
     As is typical with outboard motor practice, the engine  14  is supported so that its output shaft  32  (e.g., crankshaft) rotates about a generally vertical axis  20 . The crankshaft  32  drives a drive shaft  34  which depends from the powerhead  11  and also rotates about the generally vertical axis  20 . The driveshaft  34  extends through a drive shaft housing  18  and is suitably journalled therein for rotating about the vertical axis  20 . As seen in FIG. 1, the drive shaft housing extends from the lower tray  22  and terminates in a lower unit  36 . 
     The drive shaft  34  continues into the lower unit  36  where it drives a transmission  38  through an input gear (not shown). The transmission  38  selectively couples the drive shaft  34  to a propulsion shaft (not shown). The propulsion shaft is coupled to the propeller  40 . The transmission  38  advantageously is a forward/neutral/reverse-type transmission. In this manner, the drive shaft  34  drives the propulsion shaft in any of these operational states as described below. 
     The operational details of the transmission  38  are not essential to the present invention. Typically, in marine propulsion systems, “dog-clutch” type transmissions are used which allow the outboard motor  10  to operate in forward, neutral, and reverse drive. This type of transmission is well known in the art and thus the details are not illustrated but the main components of the transmission are described. 
     Within the transmission  38  is a bevel gear affixed to the lower end of the drive shaft  34 . The bevel gear meshes with a pair of counter rotating driven gears which are journalled in a suitable manner for rotation on the propeller shaft. The propeller shaft is, in turn, journalled in a suitable manner in the lower unit  36 . A dog-clutching sleeve has a splined connection to the propeller shaft located between the bevel gears and is axially moveable. If the dog-clutching sleeve is positioned so that the dog-clutching teeth are out of engagement with the teeth of the bevel gears, the transmission is in neutral. When the dog clutch sleeve is shifted forward along the axis of the propeller shaft, the dog clutching teeth are engaged with one of the bevel gears and the propeller shaft is driven in one direction. Alternatively, when the dog clutching sleeve is shifted backwards along the axis of the propeller shaft, it engages the other bevel gear and the propeller shaft is driven in an opposite direction. 
     The dog clutching sleeve is reciprocated by a shift mechanism  46  (FIG. 2) that includes a shift control lever  42  (FIG.  1  and FIG. 2) that is affixed to a shift control rod  44  (FIG.  1 ). As will be described in detail later, the shift mechanism  46  rotates the control lever  42  and therefore rotates the shift control rod  44 . The shift control rod  44  depends into the transmission  38 . Within the transmission  38 , by means well known in the art, rotation of the shift control rod  44  causes reciprocating movement of the dog clutch sleeve. Accordingly, rotation of the control lever  42  shifts the transmission between forward, neutral and reverse positions. 
     With reference to FIGS. 2-6, the shift mechanism  46  will be described in detail. The shift mechanism  46  cooperates with a remotely located operator unit  48  that controls the shifting mechanism  46 . In an exemplifying embodiment, the operator unit  48  is located on the steering shaft  24  (FIG. 1) of the outboard motor  10 ; however, the operator unit  48  may also lie either in the hull  22  of the watercraft or within or adjacent to the power head  11  of the outboard motor  10 . 
     A Bowden-wire-type shift cable  50  desirably couples the operator unit  48  to the shifting mechanism  46 . In the illustrated embodiment, the cable  50  has an outer casing  52 . A bracket (not shown), which is mounted within the cowling  12 , supports a portion of the cable  50  near the shift control mechanism  46  and prevents movement of the outer casing  52  of the cable  50  relative to the cowling  12 . 
     The illustrated shifting mechanism  46  includes a fitting  54  positioned at the end of the shift cable  50 . The fitting  54  is coupled to an end of a link  56 . A pivot pin  58  of the shift control mechanism  46  interconnects the cable fitting  54  and the link  56  in order to permit relative rotational movement between these components. 
     A slider  60  supports the pivot pin  58  within an elongated aperture  62 . A guide  64  supports the slider  60 . As best seen in FIG. 3, the guide  64  includes a slot or cam groove  66 . Preferably, the slot  66  defines a substantially linear path, in which the slider  60  translates. A bracket  68  supports the guide  64  and is attached by a bolt  70  to the crankcase  72  of the engine  14 . 
     As shown in FIG. 2, a shift position sensor  74  is located along a side of the guide  64 . Moreover, the shift position sensor has a portion that is preferably positioned at a substantially right-angle relative to the substantially linear path of the slider  60 . The shift position sensor  74  is generally comprised of a detection lever  76  and a sensor body  78 . During operation of the outboard motor, the shift position sensor  74  transmits a signal to a control unit  80 . The function and purpose of the shift position sensor  46  will be described later. The guide  64 , slider  60  and sensor  74  together comprise a guide mechanism  65 . 
     An opposite end of the link  56  is connected to an end of the shift control lever  42 . A pivot pin  82  couples together the ends of the link  56  and the lever  42  to allow relative rotational movement between these components of the shifting mechanism  46 . 
     As best seen in FIG. 3, the shift lever  42  has a vertical jog. A portion of the lever  42  thus lies below the end coupled to the link  56 . The shift control rod  44  is fixed to the lower portion of the shift lever  42 . As understood from FIG. 1, the shift control rod  44  depends from the power head  16  to the transmission  38 . The shift control rod  44  operates the transmission  38  to change the drive condition of the transmission  38  as described above. 
     As best understood from FIGS. 3 and 6, parts of the shift mechanism  46 , such as the link  56  and the control lever,  42  are preferably arranged and operate vertically below the crankcase  72  within a space  17  between the engine  14  and the drive shaft housing  18 . The guide mechanism, however,  65  is preferably arranged on a side of the engine  14  and crank case  72 . More preferably, the guide mechanism  65  is located in a space between the engine  14  and the cowling  12 . Moreover, as is best shown in FIG. 6, the shift position sensor  74  is preferably arranged on the outer side of the shift mechanism relative the engine  14 . More preferably, the guide  64  and slider  60  are interposed between the sensor  74  and the engine  14 . As such, the shift mechanism  46  produces a compact arrangement within the space  17  between the lower tray  16  and the cowling  12 . This location also protects the link  56  and the control lever  42 , shift rod  44  and position sensor  74  while still allowing access for assembly and repairs. 
     The operation of the shift control mechanism will now be described in detail. With reference to FIG. 2, the cable  50  is interlocked with the operator unit  48 . The shift lever  42  is in the forward position “FO”. The slider  60  is located at one end of the guide  64 . The pivot pin  58  is located at one end  62   a  of the elongated aperture  62 . In this position, the detection lever  76  of the shift position sensor  74  physically engages the slider  60 . Thus, the slider  60  is secured in this position. At this position, the sensor  76  prohibits the engine from starting by transmitting a signal to the control unit  80 . Accordingly, the sensor  76  prevents the watercraft from abruptly moving forward when started. 
     As the cable  50  begins to move in a direction “A”, the pivot pin  58  slides from one end  62   a  of the aperture toward the other end  62   b,  but the slider  60  remains still and does not slide in the “C” direction. In such a manner, play is provided in the shift mechanism  46  and the slider  60  remains still despite small movements of the cable  50 . Thus, the shift mechanism  46  includes a lost motion coupling. Preferably, this lost motion coupling is interposed between the operator unit and the shift lever. More preferably, the lost motion coupling is interposed between the operator unit  48  and the sensor  74 . Furthermore, the direction of the lost motion is preferably in the same direction as the motion of the slider. 
     When the cable  50  moves further in the “A” direction, the pivot pin  58  eventually reaches the other end  62   b  of the aperture  62 , and the slider  60  moves in the “C” direction. As shown in FIG. 4, when the cable  50  moves in the “A” direction for a certain distance, the shift lever  52  rotates to a neutral position “N” through the link  56  and pivot pin  82  as described above. The transmission  38  then shifts to the neutral position, and the engine  14  ceases power transmission to the propeller  40 . 
     When the shift lever  52  is positioned in the neutral position “N”, the detection lever  76  of the sensor  74  is physically engaged with an etched or recessed portion  84  of the slider  60 . Because of this engagement, the slider  60  is secured in this position. While in this position, the sensor  74  transmits a signal to the control unit  80  that allows the engine  14  to start. 
     As the cable  50  further slides in the “A” direction, the shift lever  42  interlocks with the movement of the cable  50  as described above and pivots to a reverse position “R” (See FIG.  5 ). Accordingly, the transmission  38  shifts into reverse gear allowing the watercraft to move in a reverse direction. 
     In the position depicted in FIG. 5, the slider  60  is located at the end of the guide  64  in the “C” direction. Although the detection lever  76  is disengaged from the recessed portion  84  of the slider  60 , the detection lever  76  is still in physical contact with the slider  60 . Therefore, the slider  60  is secured in its position at the end of the guide  64 . In this position, the sensor  74  transmits a signal to the control unit  80  that prevents the engine  14  from starting. 
     The shift lever  42  returns in order from the reverse position “R” to the neutral position “N” and forward position “FO” when the cable  50  slides in the “B” direction and the slider  60  correspondingly slides in the “D” direction to return to its original position as illustrated in FIGS. 2,  5  and  6 . Because the slider  60  slides in a linear direction, the sensor  74  can be positioned at a substantially right angle to the slider  60  and be more securely and accurately arranged as compared to prior art. Advantageously, the illustrated sensor can transmit a signal to prevent ignition or allow ignition with only two positions due to component positioning and gearing. It is envisioned, however, that other arrangements are also possible. 
     Another arrangement having certain features, aspects, and advantages in accordance with the present invention is depicted FIGS. 7-10. The illustrated arrangement is similar to that described above and similar parts have been given the same reference numbers. The following description will focus on the additional features, which are not present in the above described arrangement. 
     In addition to the shift mechanism  46  described above, there is further provided a pivot detection sensor  86 , which cooperates with the shift mechanism  46  so as to provide a signal when the transmission  38  is being shifted from either the forward drive position or the reverse drive position . This sensor forms a portion of a mechanism that will operate to slow the speed of the engine  14  and make disengagement of the dog clutching teeth easier. As with the first arrangement, this shift mechanism  46  includes a guide mechanism  65  that includes a guide  64  which defines a slot or cam groove  66  in which a pivot pin  58  and a slider  60  are journalled. 
     As best shown in FIG. 8, the guide mechanism  64  is journalled on a bracket assembly  68  that is affixed to the crank case  72  in a suitable manner, as by bolts  70  (FIG.  7 ). With reference to FIG. 8, the bracket  70  has a pivot shaft  88 . The pivot shaft  88  is preferably threaded into a pivot rod  90  formed in the base of the guide  64 . Thus, the guide  64  is journalled for pivotal movement about an axis  92  defined by the pivot shaft  88  and pivot rod  90 . 
     A torsional spring  94  encircles the pivot rod  90  and has its ends engaged with the bracket  70  and the guide  64  for urging the guide  64  for rotation about the axis  92  in a clockwise direction into engagement with a fixed stop  96  (FIG. 7) formed on the bracket assembly  58 . This is the normal position for the member  47  and corresponds to the neutral position of the shift lever  42  and slider  60  as shown in FIG.  9 . 
     As shown in FIG. 7, when shifting to the neutral position from the forward drive position, the guide  64  will be rotated in a counterclockwise direction and engage a another limit stop  98  also formed on the bracket  58 . This movement of the guide  64  is shown by the dashed lines of FIG. 7 that are referenced by the number  87 . When this rotation occurs, the pivot detection sensor  86  detects the rotation and sends a signal to the control unit  80  which will cause the slowing of the speed of the associated engine in a known manner such as by effecting misfiring of its spark plug or spark plugs. This type of circuit is well known and any of the known circuits used for this purpose may be employed. 
     Because of the angular inclination of the link  56  and the cooperation of the slider  60  with it, the counterclockwise pivotal movement will be effected regardless of whether the device is being shifted from forward or reverse drive position as may be best seen in FIG.  10 . As shown, when the slider  60  is moved in the “D” direction from its reverse position a component force is applied to the guide  64  and the guide  64  pivots from its position illustrated by a solid line to the position illustrated by the dashed line  87 . As described above, the pivot detection sensor  86  detects this movement and inputs a signal to the control unit  80 , whereby the engine  14  is disabled temporarily. 
     A third arrangement of the present invention is depicted in FIGS. 11 and 12. Elements of this arrangement that are similar to the other arrangements will be given the same reference numbers. A Bowden-wire-type shift cable  50  desirably couples the operator unit to the shifting mechanism  46 . As in the previous arrangements, the cable has an outer casing  52 . The cable  50  and the outer casing  52  are fitted to a guide  64 . A fitting  54  is positioned at the end of the cable  50  and coupled to an end of a shift control lever  42 . A pivot pin  82  of the shift mechanism  46  interconnects the cable fitting  54  and the shift control lever  42  in order to permit relative rotational movement between these components. As best shown in FIG. 11, the shift lever  42  is linked to the shift rod  44  and thus movement of the cable  50  rotates the shift rod  44  and shifts the gear of the transmission  38  as described above. 
     As shown in FIG. 12, the guide  64  is located on the cable  50  so that the cable  50  slides only in a linear direction. Furthermore, sliders  60  are mounted on the cable  30 . The sliders  60  are situated within a groove (not shown) in the guide member  64  so that they slide within the guide  64  in a linear direction. 
     A shift position detection sensor  74  is located along one side of the guide  64  at a right angle to the sliders  60  and the cable  50 . The shift position detection sensor  74  is comprised of a detection lever  76  and a sensor body  78 . During operation, the shift position sensor  74  transmits signals to a control unit  80 . The function and purpose of the shift position detection sensor  74  is as described above. Furthermore, as with the embodiments described above, the detection lever  76  physically restrains the gliders  60  in a particular position. 
     As illustrated by the dashed lines in FIG. 12, the sensor  74  detects the motion of the cable in an “A” or “B” direction by sensing the movement of the sliders  60  through the guide  64 . As such, the sensor can detect the forward, neutral and reverse positions of the shift lever  42 . The guide member  64 , sliders  60  and sensor  76  can be located anywhere on the cable  50 . This provides flexibility as to the location of the sensor  46 . As such, the sensor  46  may be located further to the side of the engine  12  as shown in FIG.  11 . Thereby, assembly and maintenance of the sensor  46  is made easier. 
     Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.