Abstract:
A shift linkage has a linkage bracket that transmits motion from a drive linkage to a driven linkage. The linkage bracket has a slot that operably engages with a guide to facilitate during an outboard marine engine operation. The slot has an upper and a lower portion such that the lower portion is configured with a lost-motion channel. A guide is disposed in the slot and is configured to ride along the lost motion channel. The drive linkage is connected to the guide to displace initial motion and the driven linkage is connected to the tongue to receive linear motion from the drive linkage. The drive linkage is connected to the guide such that the lost motion channel and the guide are engaged to produce a force having vertical and horizontal components. The vertical component engages a switch and the horizontal component transmits motion to the driven linkage.

Description:
BACKGROUND OF INVENTION 
     The present invention relates generally to shift linkage for an outboard motor, and more particularly, to a linkage assembly having a slot operably engaged with a guide to facilitate the shifting of gears during operation of the outboard motor. 
     Manual shift vehicles typically employ a clutch to facilitate shifting for engagement and disengagement of the gears in a standard shift transmission. However, in certain types of engine applications, such as marine outboard engines, there is no clutch system and gear shifting can occasionally demand more effort from an operator to shift from a positive gear position to a neutral position. 
     A typical outboard marine engine has three gearshift positions to provide operation, namely, forward, neutral, and reverse. When attempting to perform a gear shift from forward to neutral, or reverse to neutral, additional effort can be required for a number of reasons. For example, higher than normal engine speed can add pressure tending to keep the gears engaged which requires additional effort to perform a gear shift from a position where the gears are thus engaged to the neutral position where the gears are, of course, disengaged. A binding linkage can also hinder a gear shift. Further, a new gearset can add to binding until the gears are broken in. Further yet, although any one of the aforementioned criteria may not create a binding gear shift alone, a combination of these factors may create additional undesired effort in shifting from a gear position to neutral. 
     It is therefore desirable to improve the linkage mechanism of the marine outboard engine to overcome the aforementioned problems. 
     SUMMARY OF INVENTION 
     The present invention relates to a shift linkage having a linkage bracket to transmit motion from a drive linkage to a driven linkage that solves the aforementioned problems in an outboard motor. The linkage bracket has a slot that operably engages with a guide to facilitate gearshift from forward or reverse to neutral position during operation of an outboard marine engine. The arrangement provides for a lost motion effect in which initial movement of the drive linkage is translated to substantially vertical motion of the guide in the linkage bracket to activate a switch, and then further movement of the drive linkage is then translated to the driven linkage. The result of the lost motion in the direction parallel with the drive and driven linkage provides free play to the linkage to reduce gearshift binding. 
     Accordingly, the present invention includes a shift linkage having a linkage bracket, a drive linkage and a driven linkage. The linkage bracket has an upper portion and a lower portion, wherein the lower portion is offset from the upper portion. The upper portion also has a pivot point and a tongue extending downwardly from the pivot point and in a common plane with the pivot point and the upper portion. The lower portion has a slot parallel to the tongue and leading to a lost motion channel in the lower end of the slot. An upper end of the lost motion channel is wider than the slot leading to the lost motion channel thereby forming a pair of guide stops in the offset lower portion of the linkage bracket to limit the amount of vertical movement. A guide is disposed in the slot and is configured to ride along the lost motion channel. The drive linkage is connected to the tongue and the driven linkage is connected to the guide to receive linear motion from the drive linkage after an initial movement is translated to create a lost motion that enhances the transfer of the motion through the shift linkage and thus reduce the binding effect. 
     In accordance with another aspect of the invention, a shift linkage is disclosed for use in an outboard motor having an engine coupled to a marine propulsion unit having forward and reverse operation. The outboard motor includes the aforementioned shift linkage, and further includes a switch positioned about the slot of the linkage bracket and connected to an ECU of the outboard motor. A driven linkage is coupled to the marine propulsion unit at one end and to the guide of the linkage bracket at another end. Initial movement of the drive linkage is translated to substantially vertical motion of the guide in the linkage bracket to activate the switch, after which, further movement of the drive linkage is then translated to the driven linkage. 
     In accordance with yet another aspect of the invention, a method of transmitting linear motion from a drive linkage to a driven linkage through a linkage bracket to ease shifting of an outboard motor is disclosed. The method includes the steps of applying a linear force to a drive linkage, and during a first phase of shifting, the linear force causes a lost motion in a direction parallel to the linear force and creating a motion in a transverse direction to the linear force through a linkage bracket. During a second phase of shifting, the linear force causes the linkage bracket to pivot and significantly move the driven linkage in the direction parallel to the linear force. 
     Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The drawings illustrate a presently contemplated embodiment for carrying out the invention. 
     In the drawings: 
     FIG. 1 is a schematic view of an outboard marine engine employing a shift linkage constructed in accordance with one embodiment of the present invention; 
     FIG. 2 is an enlarged perspective view of a portion of FIG. 1 that includes the shift linkage constructed in accordance with the present invention; 
     FIG. 3 is an exploded perspective view of a portion of FIG. 2 showing the present invention; 
     FIG. 4 is a side plan view of a portion of FIG.  2 . 
     FIG. 5 is a cross-sectional view taken generally along line  5 — 5  of FIG. 4; 
     FIG. 6 is a cross-sectional side view taken generally along line  6 — 6  of FIG. 4 showing a switch in an open position; 
     FIG. 7 is a fragmentary sectional view of a portion of FIG. 6 showing the switch in a closed position; 
     FIG. 8A is a side plan view of a linkage bracket with accordance with the present invention in a rest, neutral position showing a portion of the shift linkage in phantom; 
     FIG. 8B is a side plan view, similar to FIG. 8A, but showing the linkage in motion during a first phase of shifting; 
     FIG. 8C is a side plan view, similar to FIGS. 8A and 8B, but showing the linkage motion during a second phase of shifting. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, there is shown a schematic view of an outboard marine engine  10  that includes an internal combustion engine  12  housed in a power head  14  and supported on a mid-section  16  configured for mounting on a transom of a boat (not shown) in a conventional manner. The output shaft (not shown) of the motor  10  is coupled to a propeller  18  extending rearwardly from a lower gear case  20  attached to the lower end of the midsection  16 . The internal combustion engine  12  may be controlled by an electronic control unit (ECU)  22 , which, in a preferred embodiment, is an integral computer. 
     The outboard marine engine  10  includes a shift linkage  24  controlled by a shift cable  34 . The shift linkage  24  is mounted on a side of the internal combustion engine  12 . A linkage bracket  28  is pivotally affixed with respect to the internal combustion engine  12 . The shift cable (hereinafter drive linkage)  34  rotates the linkage bracket, and in turn, drives a driven linkage  30  that has one end affixed to the linkage bracket  28  and the other end affixed to a driven arm  32  that is also pivotally affixed with respect to the internal combustion engine  12 . The various pivoting motions of the driven linkage  32 , the drive linkage  34  and, of course, the linkage bracket  28  will be later explained. 
     Turning now to FIG. 2, there is shown, an enlarged perspective view of the shift linkage  24  constructed in accordance with the present invention. In this Figure there can be seen the driven arm  32  is pivotally affixed to a stationary surface  38  with respect to the internal combustion engine  12 . The stationary surface  38  may be a surface of the internal combustion engine  12  itself or a fixed surface that is a part of the engine housing or other component fixed in position. As such, the pivotal mounting of the driven arm  32  may be by means of a driven arm spindle  40 , and which is, in turn, pivotally affixed to the stationary surface  38  by means such as a bolt  44  or may be welded. 
     The linkage bracket  28  is also pivotally affixed to the stationary surface  38  and that affixation can be by a similar means including a linkage bracket spindle  46  that is, in turn, affixed to the stationary surface  38  by means of a bolt  44 , thereby creating a pivot point  48  for the linkage bracket  28 . The driven linkage  30  is affixed to the linkage bracket  28  a finite distance or radial length away from the pivot point  48  and the drive linkage  34  is also affixed to the linkage bracket  28  a further radial length away from that pivot point  48 , as will later become clear, it being sufficient at this point to note that the movement of the drive linkage  34  in the direction of arrow A, will cause the linkage bracket  28  to rotate in the clockwise direction and further cause the driven linkage  30  to also move generally in the direction of the arrow A′. That clockwise rotation of the linkage bracket  28  will therefore cause the driven linkage  30  to move in the direction of the arrow A′, such that the driven arm  32  can cause the shifting of the gear position of the outboard marine engine between the reverse, neutral and forward positions, in a conventional manner. An electrical switch  50  is also mounted on the linkage bracket  28  in a specially constructed manner as will later be described. 
     Turning now to FIG. 3, there is shown an exploded perspective view of certain of the components used in construction of the shift linkage  24  of FIG.  2 . In FIG. 3 there can be seen the pivot point  48  about which the linkage bracket  28  rotates by means of the affixation with the linkage bracket spindle  46  by bolt  44  passing through an opening  54  formed in the upper portion  56  of the linkage bracket  28 . The linkage bracket  28  itself is formed in a special configuration and comprises a downwardly directed tongue  58  from that upper portion  56  and which extends downwardly from the pivot point  48  and is formed so as to be in the same plane as the opening  54  as well as the pivot point  48  and upper portion  56  of the linkage bracket  28 . A stub  60  is formed in the lower end  62  of the tongue  58  and allows the driven linkage  30  to be affixed to the linkage bracket  28  by means of the stub  60  passing through a hole  64  at the end of the driven linkage  30  and affixed together by a cotter pin  65 . 
     The linkage bracket  28  also comprises a lower portion  66  extending downwardly from the upper portion  56  and in which is formed a slot  68  of a particular configuration. The lower portion  66  and the slot  68  formed therein are in a plane that is displaced forwardly with respect to the plane of the pivot point  48  and tongue  58  as there is a forwardly extending transition portion  70  intermediate the upper portion  56  and the lower portion  66  of linkage bracket  28 . In particular, the slot  68  comprises a wide, upper portion  72 , a narrower intermediate portion  74  and a lower tapered portion  76  having a downwardly, inwardly tapered surface  78  in the general configuration of an arrow. At the upper point where the lower, tapered portion  66  intersects with the intermediate portion  74 , there is formed an abrupt shoulder forming a guide stop  79 . 
     A guide  80  is fitted for movement within the lower portion  76  of the slot  68  and the guide comprises a roller  82  having an external groove  84  formed in outer peripheral surface of the roller  82  so that the groove  84  rides along the inwardly tapered surface  78  of the lower portion  76  of slot  68 . Roller  82  further has an outwardly extending shaft  86  that passes through a hole  88  formed in the end of the drive linkage  34  and can be secured thereto by a cotter pin  90 . Thus, guide  80  is basically secured to the drive linkage  34  and guide  80 , as well. Therefore, the drive linkage  34  can be moved by the rotational movement of the linkage bracket  28 . 
     The electrical switch  50  includes a pair of spring brackets  92  that extend outwardly from both sides of the electrical switch  50  and each of the spring brackets  92  has an elongated indentation  94  (only one of which is shown) that interfit with the inner edges of the upper portion  72  of the slot  68  such that the spring brackets  92  secure the electrical switch  50  to the lower portion  66  of the linkage bracket  28 . A switch button  96  extends downwardly from electrical switch  50  and is axially movable in order to operate the electrical switch  50  i.e. by making and breaking a circuit. 
     A slide actuator  100  is positioned intermediate the electrical switch  50  and the guide  80  and operates to move the switch button  96  in its axial direction to operate the electrical switch  50 . As can be seen, the slide actuator  100  also has a pair of elongated slots  102  formed in each side thereof and the elongated slots  102  interfit with the internal edges of the intermediate portion  74  of the slot  68  so that the slide actuator  100  can freely slide along the internal edges of the slot  68  and move axially to contact and cause the switch button  96  to also move axially and thus operate the electrical switch  50 . In order to align and interfit with the switch button  96 , there is an extended housing  104  molded into the slide actuator  100  to receive and contain the switch button  96  and thus provide protection to the switch button  96  from inadvertent damage. 
     Turning now to FIG. 4, there is shown a view of the components of the shift linkage  24  of the present invention in the assembled condition. As can be seen, the linkage bracket  28  is pivotally mounted to a fixed surface which may be the internal combustion engine itself (not shown in FIG. 4) by means of the bolt  44  to constitute a pivot point  48  for the linkage bracket  28 . The driven linkage  30  is also affixed to the linkage bracket  28  as is the drive linkage  34 , the latter being connected to the linkage bracket  28  at a further distance or moment arm from that pivot point  48 . As the drive linkage  34  is moved in the direction of the arrow A, the linkage bracket  28  rotates clockwise about pivot point  48  and moves the driven linkage  30  in the direction of the arrow A′. 
     In the initial movement of the drive linkage  34  in the direction of the arrow A, however, the guide  80  moves along the internal edge of the inwardly tapered surface  78  of the lower portion  76  of slot  68  and thus the guide  80  moves in a generally vertically upward direction and not immediately in the direction of the arrow A. Thus, as the movement of the drive linkage  34  progresses, the initial movement causes the guide  80  to move in a generally vertical upward direction to cause the slide actuator to also move upwardly to depress the switch button  96  and thus activate the electrical switch  50 . Continued movement of the drive linkage  34  thus causes the guide  80  to reach a high corner or guide stop  79  at the upper corner of the tapered surface  78  where the guide  80  cannot continue further in the upward direction and the movement of the drive linkage  34  thereafter causes full movement of the driven linkage  30  in the direction of the arrow A″, thus, there is a slight lost motion between the drive linkage  34  and the driven linkage  30 . 
     Turning briefly to FIG. 5, there is shown a cross-sectional view taken along the line  5 — 5  of FIG.  4  and showing the switch button  96  captured within the extended housing  104  of the slide actuator  100  and the interfitting of the slide actuator  100  within the inner edge of the intermediate portion  74  of the slot  68 . 
     Turning next to FIG. 6, there is shown a side cross sectional view taken along the line  6 — 6  of FIG.  4  and showing, more clearly, the plane P 1  of the upper portion  56  of the linkage bracket  28  and the plane P 2  of the lower portion  66  and illustrating the displacement of those planes with respect to each other caused by the transition portion  70  of the linkage bracket  28  that is between the upper portion  56  and the lower portion  66 . Thus, the tongue  58  and the pivot point  48  are in the same plane P 1  and the lower portion  66  of the linkage bracket  28  are in another plane P 2 . 
     As also can be noted in FIG. 6, the switch button  96  is in its non-depressed or extended position since the guide  80  is at the bottom of the generally V-shaped or arrow shaped lower portion  72  of the slot  68 . Turning briefly to FIG. 7, there is shown a fragmented view of a portion of FIG.  6  and showing switch button  96  in its depressed position or upper position where the electrical switch  50  is activated. Thus, in FIG. 7, the guide  80  has moved vertically upwardly as seen by the Arrow B by sliding along the arrow shaped tapered surface  78  (FIG. 4) of the slot  68  and thus the slide actuator  100  has also moved upwardly, as is normal during the initial movement of the drive linkage  34  in the direction of the arrow A of FIG.  4 . 
     FIGS. 8A,  8 B, and  8 C illustrate the operation of the linkage bracket  28  in three different phases. As can be seen, there is a finite linear distance X from the pivot point  48  to the tip of the guide  80  that varies as the roller  82  moves upwardly and downwardly along the inwardly tapered surface  78 . Before the initial movement of the drive linkage  34 , the roller  82  is in the lowest position within the lower portion  76  of the slot  68 . As the drive linkage  34  moves in the direction of the arrow A, FIG. 8B, it causes the roller  82  to move upwardly along the tapered surface  78  along arrow B without displacing the driven linkage  30 . However, it is important to recognize that the displacement ratio between the drive linkage  34  and the driven linkage  30  is one to one (1:1) after the slack, or lost motion, is absorbed by the initial movement. Therefore, in the second phase of movement as shown in FIG. 8B, the roller  82  moves upward until it reaches its highest position on the tapered surface  78  at the guide stop  79  and closes the switch button  96  of the electrical switch  50  (not shown). In a third phase of movement, as shown in FIG. 8C, further displacement of the drive linkage  34  in the direction of the arrow A causes the linkage bracket  28  to further rotate and in turn cause the driven linkage  30  to move in the direction of the arrow A″ as shown in FIG.  8 C. 
     Referring again to FIGS. 8A and 8B, it can be seen that the length X is different in FIGS. 8A and 8B because the roller  82  is in a higher position in FIG. 8B to close the button of the switch (not shown in these Figures) and to compensate for the vertical length of the button in close/open position as best viewed in FIGS. 6 and 7. 
     The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.