Abstract:
The present invention provides a gear absolute position sensor assembly (GAPS) that senses the current absolute, position of the shift lever of a manual transmission. The sensor assembly provides data to an associated electronic controller such as an engine control module (ECM) regarding the current position of the shift lever, such as an engaged gear. The sensor assembly preferably comprises two Hall effect or other type of magnetic field (proximity) sensors in combination with an application specific integrated circuit (ASIC) which is supplied with data from the sensors, decodes the output of the sensors and provides an output identifying a specific engaged gear or neutral for use by vehicle or engine management electronics. The sensors are mounted proximate the shift linkage at a location where they can sense both rotation and translation.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/425,626, filed Dec. 21, 2010, which is hereby incorporated in its entirety herein by reference. 
     FIELD 
     The present disclosure relates to a gear absolute position sensor (GAPS) for manual transmissions and more particularly to a gear absolute position sensor for manual transmissions for engine speed matching and engine start-stop applications. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     The trend of automatic motor vehicle transmissions for passenger cars, sport utility vehicles, pickup trucks and other consumer vehicles from substantially full hydraulic operation to operation under the control of an electronic transmission control module (TCM) and hydraulic actuators has been accompanied by both the desire and necessity of providing electronic linear position sensors which provide real time data to the transmission control module regarding the current positions of the actuators, the associated shift linkages and the clutches, brakes and gears acted upon. Such data is utilized by the transmission control module to confirm, for example, the commencement and completion of a shift and thus the overall state of the transmission. Such data is also useful for self-diagnosis of impending or actual component failure. 
     This trend has not been taken up by the other significant class of motor vehicle transmissions, namely, manual transmissions. As the name suggests, such transmissions are manually shifted by the vehicle operator. Since shift timing and gear selection are left to the vehicle operator, the incorporation of various sensors in a manual transmission has been viewed as not only unnecessary but as an invasion of the operator&#39;s freedom. 
     Nonetheless, it is apparent that data regarding the current operating state of a manual transmission can be utilized by associated electronic controllers to improve the overall driving experience. The present invention is so directed. 
     SUMMARY 
     The present invention provides a gear absolute position sensor assembly (GAPS) that senses the absolute, current shift lever position or chosen or engaged gear of a manual transmission. The sensor assembly provides data to an associated electronic controller such as an engine control module (ECM). The sensor assembly preferably comprises two Hall effect or other type of magnetic field (proximity) sensors in combination with an application specific integrated circuit (ASIC) which is supplied with data from the sensors, decodes the output of the sensors and provides an output identifying a specific engaged gear or neutral for use by vehicle or engine management processors. The sensors are mounted proximate the shift linkage at a location where they can sense both rotation and translation. 
     The sensor assembly may be utilized with four, five, six or more speed and gear ratio manual transmissions. Use of the sensor assembly enables engine and transmission speed matching which reduces clutch wear and provides improved shift quality. The sensor assembly also enables engine start-stop capability as well as remote start for a manual transmission by, inter alia, detecting when the transmission is in neutral. The sensors and the application specific integrated circuit also provide full diagnostic capability. 
     Thus it is an aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission. 
     It is a further aspect of the present invention to provide a gear absolute position sensor (GAPS) for a manual transmission. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two magnetic proximity sensors. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two Hall effect sensors. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having an application specific integrated circuit. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two sensors mounted proximate the shift linkage. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having four, five, six or more speeds or gear ratios. 
     It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having full diagnostic capability. 
     Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is block diagram of the relevant electrical, electronic and mechanical components of a motor vehicle having a manual transmission and equipped with the present invention; 
         FIG. 2  is a perspective view of a portion of a manual transmission including a shift linkage incorporating the present invention; 
         FIG. 3  is an enlarged view of a manual transmission shift linkage incorporating the present invention; 
         FIG. 4  is a plan view of a typical and representative six speed manual transmission shift gate (“H”) pattern; 
         FIGS. 5A ,  5 B and  5 C are diagrammatic views of the gear shift linkage and sensors according to the present invention in neutral, a forward gate position for odd numbered gears and a rearward gate position for even numbered gears, respectively; 
         FIG. 6  is a chart presenting exemplary rotations and translations of the shift linkage of  FIG. 3  associated with engaging the six forward speeds or gear ratios and reverse of the manual transmission illustrated in  FIG. 2 ; 
         FIG. 7  is a diagram graphically illustrating the various positions of the shift linkage and the duty cycles (% PWM) of the two sensors corresponding to such positions according to the present invention; and 
         FIG. 8  is a graph illustrating the sensor duty cycle (% PWM) of the two sensors for various positions of the shift linkage according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     With reference to  FIG. 1 , the relevant electrical, electronic and mechanical components of a motor vehicle having a manual transmission equipped with the present invention are illustrated and generally designated by the reference number  10 . The components  10  include a prime mover  12  which may be a gasoline, Diesel or flex fuel engine, or a hybrid or electric power plant. The prime mover  12  includes an output shaft  14  which drives a main friction clutch  16  which is typically, though not necessarily, engaged and disengaged by the vehicle operator (not illustrated). The main clutch  16  selectively provides drive torque to an input shaft  18  of a manual transmission  20 . The manual transmission  20  may be conventional and includes a housing  22  as well as shafts, gears and synchronizer clutches (all not illustrated) which cooperatively provide, for example, four, five, six or more forward speeds or gear ratios and reverse. The transmission includes an output shaft  24  which is coupled to a final drive assembly  26  which may include, for example, a propshaft, a differential assembly and a pair of drive axles. A driver interface  28  generally includes those controls and devices under the control of and operated by the vehicle operator (not illustrated). 
     The components  10  also include a plurality of electric and electronic sensors which provide real time data to an engine control module (ECM)  30 . For example, an electronic sensor (tachometer)  32  disposed in the prime mover  12  provides a signal representing the current speed of the output shaft  14  of the prime mover  12 . A transmission input speed sensor (TISS)  34  senses the instantaneous speed of the input shaft  18  of the manual transmission  20 . A transmission output speed sensor (TOSS)  36  senses the instantaneous speed of the output shaft  24  of the manual transmission  20 . A gear absolute shift position sensor assembly  40  according to the present invention includes an application specific integrated circuit  44 , the data output of which indicates the current position of a shift lever  72 . A clutch position sensor  52  senses the position of the main clutch  16 . A throttle position sensor  54  senses the instantaneous position of a throttle pedal (not illustrated). A brake pedal position sensor  56  sense the position of a brake pedal (also not illustrated). A body control module (BCM)  60  receives data from one or more control switches  62  and includes a data output to the engine control module  30 . 
     Referring now to  FIGS. 2 ,  3  and  4 , attached to the exterior of the housing  22  of the manual transmission  20  is a shift linkage  70 . The shift linkage  70  includes a shift lever  72  which terminates in a shift ball or handle  74  that is engaged and manipulated by the vehicle operator. The shift lever  72  is moveable through a virtual or actual shift gate or “H” pattern  76 , illustrated in  FIG. 4 , which facilitates selection of, separates and creates tactile feedback for six forward gears or speed ratios and reverse. It should be understood, however, that the manual transmission  20  with which the present invention is utilized may incorporate and provide more or fewer gears or speed ratios. The shift lever  72  is disposed in a ball pivot  78  and coupled to a longitudinally oriented shaft  80  which is supported by various mounting members or brackets and bearings  82  which allow it to translate fore and aft and rotate about its axis. 
     Referring now to  FIGS. 3 ,  5 A,  5 B and  5 C, the gear absolute position sensor assembly  40  includes a first arc magnet or ring  92  and a spaced apart second arc magnet or ring  94 , both secured to the longitudinally oriented shaft  80 . In the neutral position of the shift linkage  70  illustrated in  FIG. 5A , a first Hall effect sensor  96  is disposed proximate, but preferably not in contact with the first arc magnet or ring  92  and a second Hall effect sensor  98  is disposed proximate, but preferably not in contact with, the second arc magnet or ring  94 . The outputs of the first Hall effect sensor  96  and the second Hall effect sensor  98  are fed directly to the application specific integrated circuit  44  which may be formed and assembled integrally with the sensors  96  and  98  into a unitary device. Alternatively, a single arc magnet or ring and a proximate single three dimensional (3D) Hall effect sensor may be utilized in place of the two rings  92  and  94  and the two one dimensional (1D) Hall effect sensors  96  and  98 . 
     It will be appreciated that the first and second arc magnets or rings  92  and  94  and the associated Hall effect sensors  96  and  98  may be mounted within the transmission housing  22 , through the transmission housing  22  or at any convenient location where the rings  92  and  94  may be attached to the shaft  80  and the sensors  96  and  98  mounted proximately. For example, they may be mounted within or near the bracket or bearing  82  illustrated in  FIG. 2 . As an alternative to Hall effect sensors, anisotropic magneto resistance (AMR), giant magneto resistance (GMR), permanent magnet linear contactless displacement (PLOD), linear variable displacement transformer (LVDT), magneto elastic (ME) or magneto inductive (MI) sensors may be utilized. 
       FIG. 5B  illustrates the position of the shaft  80  when the shift lever  72  is in a forward position in the shift gate  76 , selecting, for example, reverse, first, third or fifth gears. Here, the first arc magnet or ring  92  is remote or spaced from both the first and the second Hall effect sensors  96  and  98  and the second arc magnet or ring  94  is in proximate, sensed relationship with the first Hall effect sensor  96 . Rotation of the shaft  80  and the second arc magnet or ring  94  adjacent the first Hall effect sensor  96  changes or modulates the magnetic field strength sensed by the first Hall effect sensor  96  and this information is utilized by the application specific integrated circuit  44  to provide a data signal indicating the absolute, current gear shift position, as described more fully below. 
       FIG. 5C  illustrates the position of the shaft  80  when the shift lever  72  is in a rearward position in the shift gate  76 , selecting, for example, second, fourth or sixth gears. Here, the second arc magnet or ring  94  is remote or spaced from both the first and the second Hall effect sensors  96  and  98  and the first arc magnet or ring  92  is in proximate, sensed relationship with the second Hall effect sensor  98 . Rotation of the shaft  80  and the first arc magnet or ring  92  adjacent the second Hall effect sensor  98  changes or modulates the magnetic field strength sensed by the second Hall effect sensor  98  and this information is utilized by the application specific integrated circuit  44  to provide a data signal indicating the absolute, current gear shift position, as described more fully below. 
     Referring now to  FIG. 6 , the actual forward and rearward translations and clockwise and counterclockwise rotations of the shaft  80  relative to the neutral position are presented for each of the six forward speed or gear ratio positions and reverse. It should be appreciated that the translations and rotations presented in  FIG. 6  are illustrative and exemplary only and that such numerical values may vary and be adjusted widely to accommodate various transmission sizes, configurations and designs including those having a different number of gears. It should also be appreciated that although the shift linkage  70  described herein functions with first selection (lateral) motion of the shift lever  72  followed by shift (longitudinal) motion (and first rotational motion of the shaft  80  and the magnet rings  92  and  94  and then longitudinal motion), the invention also encompasses a shift linkage  70  in which the shaft  80  and the magnet rings  92  and  94  first move longitudinally and then rotate in response to motion of the shift lever  72 . 
     Referring now to  FIG. 7 , a diagram corresponding to the shift gate or “H” pattern  76  illustrated in  FIG. 4 , presents the PWM duty cycle output of the application specific integrated circuit  44  in percent for each of the Hall effect sensors  96  and  98  as a function of the location of the shift lever  72  and the shaft  80 . Note, first of all, that for all neutral positions, the duty cycle output values for both the sensors  96  and  98  are identical, thus providing a useful integrity check on system and sensor operation. Second of all, in both forward positions in the shift gate pattern  76 , selecting, for example, reverse, first, third or fifth gears, as illustrated if  FIG. 5B , and rearward positions in the shift gate pattern  76 , selecting, for example, second, fourth and sixth gears, as illustrated in  FIG. 5C , one of the outputs of the Hall effect sensors  96  and  98  is always zero; the second Hall effect sensor  98  in the first instance and the first Hall effect sensor  96  in the second instance. 
     Referring now to  FIG. 8 , a graph illustrates the actual continuous state output (PWM duty cycle in percent) of the application specific integrated circuit  44  from the first Hall effect sensor  96  along the horizontal (X) axis and the output of the application specific integrated circuit  44  from the second Hall effect sensor  98  along the vertical (Y) axis as the shaft  80  and the shift lever  72  move through the various positions of the shift gate pattern  76  while selecting one of the available gears or speed ratios. From this graph, as well as the data of  FIG. 7 , it will be appreciated that not only each gear selection position has a unique numerical value or signature but also that as the shift lever  72  is moved and the shaft  80  is translated and rotated, the outputs of the Hall effect sensors  96  and  98  and the application specific integrated circuit  44  provide a continuously varying, essentially analog, signal that permits the engine control module  30  or other, similar device to infer not only the present location of the shift lever  72  and the shaft  80  but also their direction of motion and the speed of such motion. 
     It should be appreciated that the gear absolute position sensor assembly  40  of the present invention provides and enables several benefits and features. For example, it supports engine start-stop applications inasmuch as they require neutral position detection. The invention improves shift quality and reduces driveline clunk by facilitating the pre-synchronization of the driveline. Additionally, matching of the speed of the engine output and transmission input, which requires absolute gear position and the anticipated gear, is possible. Torque management which may reduce transmission mass and complexity is also possible. Remote, i.e., unattended, starting is also facilitated since it, too, requires neutral position detection. Furthermore, the invention may be utilized to reduce or substantially eliminate abuse of the transmission as it may be utilized to sense and prevent a potentially abusive operational event. Finally, the invention provides full diagnostic capability, for example, short to power, short to ground and open circuit. 
     The description of the invention is merely exemplary in nature and 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.