Patent Publication Number: US-2006005655-A1

Title: First gear/reverse gate indicator switch

Description:
REFERENCE TO RELATED APPLICATIONS  
      This application is a divisional of U.S. patent application Ser. No. 09/824,276 filed on Apr. 2, 2001. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates generally to a switch which indicates when a shift lever of a manually controlled transmission is positioned in or is entering the first gear/reverse gate.  
      Manual transmissions commonly include a reverse biasing mechanism including an interlock and a detent mechanism. The reverse biasing mechanism provides feedback, or a shift feel, to the vehicle operator to indicate where the vehicle operator is in the shift pattern. During vehicle operation, a the shift lever is moved towards a first gear/reverse gate, the detent mechanism coacts with a contoured surface on the interlock and provides resistance in the shift lever. This resistance alerts the vehicle operator that the transmission is in or about to engage the first gear or the reverse gear.  
      Some vehicle operators may desire a large number of speeds, whereas other operators may not. A typical multi-speed heavy vehicle manual transmission includes a main transmission gear box including five forward speeds and a reverse speed. At times it is desirable to have more speeds ratios, such as when driving through mountains. However, it may be undesirable to have an increased number of speed ratios when driving on flat landscape. Additionally, having many available speeds complicates shifting.  
      A range box and a splitter box are commonly utilized to increase the number of speeds available, making it possible to change the number of speeds in a transmission without have to replace the transmission. The range box modifies the five forward speeds between a HIGH range and a LOW range, doubling the number of available speeds to ten.  
      The splitter box can be utilized to split the speed ratios within each of the five main gears in the main transmission, also providing for a greater number of different speed. In this way, the splitter box also doubles the number of available speed ratios. In a manual transmission, the splitter box is only utilized while the transmission is in the first gear. During acceleration when pulling a heavy load, it is desirous to utilize the splitter box only when the transmission is in the first gear or low reverse gear to provide for more speed or to allow the vehicle to “creep.” 
      Hence, there is a need in the art for a switch which indicates when a shift lever of a manually controlled transmission is positioned in or is entering the first gear/reverse gate.  
     SUMMARY OF THE INVENTION  
      The present invention relates to a switch which indicates when a shift lever of a manually controlled transmission is positioned in or entering the first gear/reverse gate.  
      In one embodiment, the manual transmission of the present invention includes a reverse biasing assembly including an interlock and a detent. The interlock includes a contoured perimeter having an arcuate surface and an adjacent elevated ramp. The detent includes a moveable housing positionable by a spring. The moveable housing contacts and rides along the contoured perimeter of the interlock to provide resistance and a shift feel.  
      When the manual transmission is in either the first gear or the reverse gear, the interlock is positioned such that the elevated ramp is aligned with the housing, compressing the spring. The manual transmission further includes a detent switch including a contact pin and a contact switch. When the transmission is in the first gear or the reverse gear, the surface of the housing pushes the contact pin into engagement with the contact switch, indicating that the transmission is in either the first or reverse gate.  
      When the manual transmission is shifted into another forward gear in the second gate or third gate, the interlock is rotated such that the arcuate surface is aligned with the housing, expanding the spring. As the spring expands, the housing moves towards the interlock and the contact pin slides into a recessed portion located on the housing. The contact pin breaks contact with the contact switch, indicating that the transmission is not in the first or reverse gate.  
      While the disclosed embodiment is preferred, other switch embodiments may be used. Accordingly, the present invention provides a switch which indicates when a shift lever of a manually controlled transmission is positioned in or is entering the first gear/reverse gate.  
      These and other features of the present invention will be best understood from the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The various features and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
       FIG. 1  illustrates a side view of a manually operated transmission;  
       FIG. 2  illustrates a cross sectional side view of the reverse biasing assembly of the present invention when the transmission is in a reverse gear or a first gear; and  
       FIG. 3  illustrates a cross sectional side view of the reverse biasing assembly of the present invention when the transmission is in a forward gear other than the first gear. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A manual transmission  10  for a heavy vehicle having a shift pattern P is illustrated in  FIG. 1 . In the preferred embodiment, the shift pattern P includes a reverse gear and five forward gears. A shift lever  12  extends through an aperture  14  in a top cover  16 . The top cover  16  supports transmission components and defines shift pattern P. The shift lever  12  is in a first gear/reverse gate when the manual transmission  10  is in a reverse gear or the first gear. The shift lever  12  is in a second gate and a third gate when the manual transmission  10  is in the second and third gears, and the fourth and fifth gears, respectively.  
      The shift lever  12  includes a first portion  18  and a second portion  20 . When an operator moves the first portion  18  of the shift lever  12  in one direction, the second portion  20  of the shift lever  12  moves in the opposite direction. When a vehicle operator moves the shift lever  12  through the shift pattern P, the shift lever  12  operatively moves a shift fork  22 . In this embodiment, there are three shift forks  22 . The shift fork  22  engages a clutch collar which engages a gear, causing a gear shift.  
      A manual transmission  10  further includes a range box  24  and a splitter box  26 . The range box  24  modifies the five forward speeds to create double the number of speeds, creating five speeds in a HIGH range and five speeds in a LOW range. A splitter box  26  is utilized to split the speed ratios between the forward gears, also providing for a larger number of speed ratios. In the preferred embodiment, the splitter box  26  is only utilized when the transmission is in the first gear or the reverse gear. By splitting the first or reverse gear, more power or torque can be provided to pull a heavy load and allow the vehicle to “creep.” 
      It should also be understood that splitter gears are sometimes only utilized in other gear speed combinations. As an example, it is known to provide the splitter function only at the highest gear ratios.  
      The second portion  20  of the shift lever  12  is pivotally received within an aperture  28  in an arm  30  of a shift sleeve  32 , the shift lever  12  permitting translational and rotational movement to the shift sleeve  32 . The shift sleeve  32  further includes a finger  34  perpendicularly oriented to the arm  30 . During shifting, the shift finger  34  operatively and selectively engages shift components to cause a gear shift.  
      The shift sleeve  32  is fixedly attached to a shift rail  36  by a fastener  38  so that the shift rail  36  moves with the shift sleeve  32 . As the first portion  18  of the shift lever  12  is moved forward by the vehicle operator, the shift rail  36 , through the shift sleeve  32 , translates rearwardly along axis A. Conversely, as the first portion  18  of the shift lever  12  is moved rearwardly, the shift rail  36  is translated along axis A forwardly. When the first portion  18  of the shift lever  12  is moved from side to side, the shift rail  36  rotates about axis A. After moving the shift lever  12 , the shift rail  36  operatively moves a shift fork  22 , engaging a desired gear to cause a gear shift.  
      As illustrated in  FIGS. 2 and 3 , the manual transmission  10  further includes a reverse biasing assembly  40  including an interlock  42  and a detent  44 . The reverse biasing assembly  40  provides feedback, or a shift feel, to the vehicle operator during shifting to indicate where the vehicle operator is in the shift pattern P.  
      The interlock  42  locks out others shift components and gears during a gear shift and reacts with the detent  44  to provide resistance in the shift lever  12 . The interlock  42  is positioned about the shift sleeve  32  and rotates with the shift sleeve  32  as the shift lever  12  is moved from side to side.  
      The interlock  42  includes a first half  46  and an opposing second half  48 . When the interlock  42  is positioned abut the shift sleeve  32 , the shift finger  34  is oriented within an aperture  50  in the first half  46  of the interlock  42  to operatively and selectively engages shift components to cause a gear shift during shifting. The first half  46  of the interlock  42  locks out surrounding shift components to prevent accidental shifting of the gears. The opposing second half  48  includes a contoured perimeter  52  with an arcuate surface  54  and an adjacent elevated ramp  56 . The arcuate surface  54  is equidistant from axis A and the elevated ramp  56  is positioned at a distance farther from axis A.  
      The detent  44  includes a spring  58  secured to a housing  60 . The housing  60  includes a contact surface  62  which contacts and rides along the contoured perimeter  52  of the interlock  42 , providing resistance and a shift feel.  
      During operation, when the first portion  18  of the shift lever  12  is moved away from neutral in shift pattern P and into either reverse gear or first gear (in the first gear/reverse gate), the shift rail  36  and the attached interlock  42  rotate such that the contact surface  62  of the detent  44  substantially contacts and rides along the ramp  56  of the interlock  42 . The spring  58  compresses, increasing the resistance in the shift lever  12  and alerting the vehicle operator that the shift lever  12  has selected a gear in the first gear/reverse gate. The first/revere gate also includes a neutral gear.  
      When the manual transmission  10  is shifted into another forward gear other than the first gear, the shift rail  36  and the attached interlock  42  rotate such that the contact surface  62  of the detent  44  substantially contacts the arcuate surface  54  of the interlock  42 . As the arcuate surface  54  is closer to axis A than the ramp  56 , the spring  58  expands as the contact surface  62  sides along the interlock  42 , decreasing resistance in the shift lever  12 .  
      The manual transmission  10  of the present invention further includes a detent switch  64  attached to the top cover  16 . The detent switch  64  is substantially perpendicular to the housing  60 . The detent switch  64  includes a contact pin  66  which rides along the exterior surface  68  of the housing  60  and a switch  70 .  
      A recessed portion  72  is positioned on the exterior surface  68  of the housing  60 . When the manual transmission  10  engages a gear in first gear/reverse gate, the contact surface  62  substantially contacts the ramp  56  of the interlock  42 , compressing the spring  58 . In this position, the exterior surface  68  of the housing  60  pushes the contact pin  66  into substantial engagement with the switch  70 , indicating that the manual transmission  10  is in either in first gear or the reverse gear.  
      When the manual transmission  10  is shifted to another forward gear which is not in the first gear/reverse gate, the interlock  42  rotates so that the contact surface  62  of the housing  60  substantially contacts the arcuate surface  54  of the interlock  42 . The spring  58  expands to move the contact surface  62  of the detent  44  towards the interlock  42 , releasing tension in the spring  58 .  
      As the spring  58  expands and housing  60  slides towards the interlock  42 , the contact pin  66  of the detent switch  64  substantially engages in the recessed portion  72  in the exterior surface  68  of the housing  60 . When the contact pin  66  slides into the recessed portion  72 , the contact pin  66  break contact with the switch  70 . This indicates that the manual transmission  10  is not in a gear in the first gear/reverse gate (reverse gear or first gear). In the preferred embodiment the contact pin  66  is a pin. However, the contact pin  66  can also consist of a plurality of balls.  
      The detent switch  64  of the present invention determines if the manual transmission  10  engages either the first gear or the reverse gear. If this is determined, additional speed can be employed in the first gear by utilizing the splitter box  26 . The splitter box  26  can only be utilized if the contact pin  66  contact the switch  70 .  
      Additionally, the splitter box  26  can only be utilized if the range box  24  indicates that the manual transmission  10  is in the LOW range. A range switch  74  determines if the manual transmission  10  is operating in the HIGH range or the LOW range. If the range switch  74  indicates that the manual transmission  10  is in the HIGH range, the range switch  74  prevents the splitter box  26  from the being utilized.  
      Additionally, a neutral switch  76  is employed to determine if the manual transmission  10  is in neutral or in a gear. If the neutral switch  76  indicates that the manual transmission  10  is in neutral, the neutral switch  76  prevents the splitter box  26  from being utilized.  
      To utilize the splitter box  26 , the vehicle operator flips a switch in the vehicle cab. In order for the vehicle operator to utilize the splitter box  26 , the detent switch  64  must indicate that the manual transmission  10  is in the first gear/reverse gate. Additionally, the range switch  74  must indicate that the manual transmission  10  is in the LOW range, and the neutral switch  76  must indicate that the manual transmission  10  is not in neutral. Once all three switches  64 ,  76 ,  78  are aligned, the splitter box  26  can be utilized by the vehicle operator.  
      In the preferred embodiment, the splitter box  26  can only been utilized when the detent switch  64  indicates that the manual transmission  10  is in the first gear or reverse gear. However, in another embodiment, the splitter box  26  can only be utilized when the detent switch  64  indicates that the manual transmission  10  is any gear other than the first gear or the reverse gear. In this embodiment, the splitter box  26  could only be utilized when the contact pin  66  does not engage the switch  70 . Also, a particular switch could be utilized to determine that the transmission is in some other set of gear ratios such that the splitter function could be enabled only for those gear ratios.  
      There are several advantages to utilizing a detent switch  64 . For one, by combining the reverse biasing mechanism  40  with a detent switch  64 , the splitter box  26  can only be utilized when the manual transmission  10  is in a gear in the first gear/reverse gate.  
      The present invention provides a combined reverse gate indicator switch. While a particular switch embodiment has been disclosed, it should be understood that other switch embodiments would come within the scope of this invention. Generally, the invention relates to the provision of a switch that provides feedback to a splitter system whether a transmission is in a particular set of gear speeds, or a single gear speed, at which the splitter function will be enabled.  
      The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specially described. For that reason the following claims should be studied to determine the true scope and content of this invention.