Abstract:
An index torque measurement system is provided. The system includes a blocker ring and a source, of index torque. The source of index torque applies a varying amount of index torque to the blocker ring to allow smooth indexing of the blocker ring teeth with synchronizer sleeve teeth. The system includes a synchronizer sleeve drivable to overcome the index torque to engage the blocker ring. The system further includes a measurement system that measures the force to overcome the index torque based on a load required to drive the synchronizer sleeve into engagement with the blocker ring given the applied index torque.

Description:
FIELD 
       [0001]    The present disclosure relates to transmissions systems, and more particularly to an index torque measurement system for a synchronizer of a dual clutch transmission. 
       BACKGROUND 
       [0002]    The transmission is a major component that transmits engine power and speed to the wheels upon driver&#39;s demand. Thus, the operating efficiency of the transmission or its ability to transmit maximum power with minimum losses is recognized as an essential item of transmission design and development. In an automatic transmission, for example, the efficiency of the transmission is about 85% to about 87%, which proportionately affects fuel efficiency. In a manual transmission, for example, the efficiency of the transmission is about 96% or better efficiency, which results in relatively improved fuel economy. Thus, manufacturers are looking to design an automatic transmission with an improved efficiency. 
         [0003]    The new technology combines best of both the systems for added efficiency and enhanced fuel economy as well as automatic shifting. Manual transmission architecture with synchronizers may be used for maximum efficiency, and launch clutches, wet or dry, may be used with electronics along with mechanical or hydraulic actuation systems to effect automatic shifting. 
         [0004]    The design of synchronizers is largely dependent upon clutch drag and transmission system efficiency: the lower the drag, the higher the efficiency, the higher the fuel economy, and the smoother the gear transition. Therefore, it may be desirable to measure the index torque of the synchronizer as designed for comparison with the drag torque to ensure that the index torque is greater than drag torque for smooth shiftability. 
       SUMMARY 
       [0005]    An index torque measurement system includes a blocker ring and a source of index torque. The source of index torque applies a varying amount of index torque to the blocker ring to allow smooth indexing of the blocker ring teeth with synchronizer sleeve teeth. The system includes a synchronizer sleeve drivable to overcome the index torque to engage the blocker ring. The system further includes a measurement system that measures the force to overcome the index torque based on a load required to drive the synchronizer sleeve into engagement with the blocker ring given the applied index torque. 
         [0006]    Further 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 
         [0007]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0008]      FIG. 1  is a schematic illustration of an index torque measurement system according to the principles of the present disclosure; 
           [0009]      FIG. 2  is a graph representing the output of the index torque measurement system of  FIG. 1 ; and 
           [0010]      FIG. 3  is a flow chart illustrating a method of measuring the index torque using the index torque measurement system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. Although the following description is related generally to an index torque measurement system for a synchronizer for use with a dual clutch transmission in a motor vehicle, it will be understood that the index torque measurement system as described and claimed herein is applicable to any type of transmission system or gear application in which it may be desirable to determine the index torque. Therefore, it will be understood that the following discussion is not intended to limit the scope of the appended claims to only motor vehicles or dual clutch transmission applications. 
         [0012]    With reference to  FIG. 1 , an index torque measurement system  10  is shown. The index torque measurement system  10  provides data that enables a comparison between a calculated and an actual measured index torque for a given synchronizer. The synchronizer should be designed with an index torque that compensates for the drag torque to successfully engage the synchronizer sleeve in gear. The index torque measurement system  10  enables the analysis of actual index torque changes when a geometry or coefficient of friction change is made to the synchronizer, as the index torque measurement system  10  may be used with a variety of synchronizer geometries. The index torque measurement system  10  includes a blocker ring  12 , a source of index torque  14 , a synchronizer assembly  16 , a crank system  18  and a measurement system  20 . The index torque measurement system  10  may be used to determine the index torque associated with the synchronizer assembly  16 . 
         [0013]    The blocker ring  12  is fixedly mounted to a rotatable shaft  22 , which is coupled to a load cell  24 . As the blocker ring  12  may comprise any suitable conventional blocker ring, the blocker ring  12  will not be described in great detail herein. Briefly, however, the blocker ring  12  may include a frictional surface or a frictional element with varying numbers of teeth  26 . The teeth  26  may be configured to interface with the synchronizer assembly  16 , and may be configured such that the blocker ring  12  rotates or indexes upon initial contact between the blocker ring teeth  26  and the synchronizer assembly  16 . The rotation of the blocker ring  12  in turn rotates the rotatable shaft  22 , and this rotation is measured by the load cell  24 . The load cell  24  may comprise any suitable force measurement device, such as a  500  pound load cell, which measures the load applied to the blocker ring  12  in terms of an output voltage. The load cell  24  is in communication with the measurement system  20  to provide the measurement system  20  with the output voltage, and the measurement system  20  converts the received output voltage into pound-force, as will be discussed. 
         [0014]    The source of index torque  14  is coupled to the rotatable shaft  22 . The source of index torque  14  includes a moment arm  28  and a known weight  30 . The moment arm  28  may comprise a beam, with a known length, that is coupled to the rotatable shaft  22 . The moment arm  28  may have any desired length, such as between about 0.200 meters to about 0.500 meters, that is capable of simulating an index torque on the rotatable shaft  22 , and thus, the blocker ring  12 . The weight  30  is coupled to the moment arm  28  at the location desired to create the index torque. Generally, the weight  30  is coupled near an end of the moment arm  28  to induce a larger torque on the rotatable shaft  22 . The weight  30  may be coupled to the moment arm  28  through any suitable technique, such as a cable, mechanical fasteners, clamps, etc. Depending upon the length of the moment arm  28  and the weight  30 , the index torque may be calculated as: 
         [0000]      Index Torque=Length of moment arm×Force   (1) 
         [0015]    Wherein the force is the weight  30 . 
         [0016]    The synchronizer assembly  16  has a synchronizer hub  34 . The synchronizer hub  34  is coupled to a fixed shaft  32 . As the synchronizer hub  34  may comprise any suitable conventional synchronizer hub, the synchronizer hub  34  will not be discussed in great detail herein. The synchronizer assembly  16  also includes a synchronizer sleeve  36 , and a plurality of strut detents  38 . The synchronizer sleeve  36  is slidingly coupled to the synchronizer hub  34 , and includes the detents  38 , and a plurality of teeth  39  (shown in phantom). Typically, the synchronizer hub  34  includes about three detents  38 , evenly spaced about a circumference of the synchronizer sleeve  36 . The detents  38  move axially in reaction to an axial load received from the crank system  18 , and set the blocker ring  12  for engagement with the synchronizer sleeve  36 . The first engagement between the blocker ring  12  and the synchronizer sleeve  36  is generally the engagement or contact between the teeth  39  of the synchronizer sleeve  36  and the teeth  26  of the blocker ring  122 . 
         [0017]    The crank system  18  applies the axial load to the synchronizer sleeve  36 . The crank system  18  includes a crank arm  40  and a plurality of load pins  42 . The crank arm  40  is slideably supported, by an arm  45  for example, such that it may be rotated relative to the synchronizer sleeve  36 . The crank arm  40  is coupled to the load pins  42  such that the rotation of the crank arm  40  drives the load pins  42  axially relative to the synchronizer sleeve  36 . The load pins  42  may be spaced about a circumference substantially equivalent to the circumference of the synchronizer sleeve  36  such that the load pins  42  contact the sleeve axially. By contacting the synchronizer sleeve  36 , the load pins  42  may apply the axial load generated by the rotation of the crank arm  40  to the synchronizer sleeve  36 . As will be discussed, the axial load from the crank system  18  may overcome the induced index torque to enable the synchronizer sleeve  36  to move linearly to engage the blocker ring  12 . The linear displacement of the synchronizer sleeve  36  is measured by a linear variable differential transformer (LVDT)  44 . The LVDT  44  measures the linear displacement of the synchronizer sleeve  36  and transmits the linear displacement measurement as an output voltage to the measurement system  20 . 
         [0018]    The measurement system  20  receives the linear displacement of the synchronizer sleeve  36  from the LVDT  44 , and computes force to overcome the index torque based on the index torque, the linear displacement of the synchronizer sleeve  36  and the axial load measured by the load cell  24 . The measurement system  20  includes a controller  50 . The controller  50  may include a voltage signal converter box  52  and a graphical user interface (GUI)  54 . The voltage signal converter box  52  receives the output voltage from the load cell  24  and the output voltage from the LVDT  44 . Given the output voltage from both the load cell  24  and the LVDT  44 , the voltage signal converter box  52  converts the output voltage into pound-force and linear displacement, respectively. The voltage signal converter box  52  then outputs these restored values to the GUI  54 . Based on the received pound-force, linear displacement and known index torque, as shown in  FIG. 2 , the GUI  54  populates a graphical representation  55  of a measured index torque  56  and a calculated index torque  58  in Newton-meters (N-m) versus an axial force  60  in Newtons (N). In addition, the raw data collected by the controller  50  may be output in a tabular format and manipulated as desired, not shown. 
         [0019]    With reference now to  FIG. 3 , a method of using the index torque measurement system  10  is shown. At block  100 , the appropriate blocker ring  12  is mounted to the rotatable shaft  22 . At block  102 , the synchronizer assembly  16  is coupled to the fixed shaft  32 . In this regard, synchronizer assembly  16  is slideably assembled on synchronizer hub  34 , which is coupled to the fixed shaft  32 . At block  104 , the load cell  24  is coupled to the rotatable shaft  22  and the controller  50 , while the LVDT  44  is coupled to the fixed shaft  32  and the controller  50 . At block  106 , the moment arm  28  is coupled to the rotatable shaft  22 , and the weight  30  is coupled to the moment arm  28  to simulate an index torque on the blocker ring  12 . The index torque created by the source of index torque  14  is the torque that must be overcome to enable the synchronizer sleeve  36  to engage the blocker ring  12 . 
         [0020]    At block  108 , the controller  50  may be activated to begin the collection of the output voltage generated by the load cell  24  and LVDT  44 . At block  110 , the crank arm  40  is rotated to apply a consistent axial load to the synchronizer sleeve  36  via the contact between the load pins  42  and the synchronizer sleeve  36 . As the crank arm  40  is rotated, the teeth  39  of the synchronizer sleeve  36  will contact and engage the teeth  26  of the blocker ring  12 . At block  112 , the controller  50  measures or records the force required to overcome the index torque. At decision block  114 , the method determines if the measured and calculated index torque values agree by determining if the axial load applied by the crank system  18  is great enough to overcome the index torque and index the blocker ring  12  so that the synchronizer sleeve  36  may pass through the blocker ring  12 . If the axial load is great enough to overcome the index torque, then the method goes to block  116 . If the axial load is not great enough to overcome the index torque, the method goes to block  118 . At block  116 , the data collection by the controller  50  is stopped and the measured index torque is output to the GUI  54 . The data may be output to the GUI  54  in any format, such as a graphical or tabular format, as discussed. At block  118 , the synchronizer assembly  16  is redesigned so that the index torque is greater than the drag torque on the synchronizer assembly  16 . Then, the method is repeated to measure the index torque for the redesigned synchronizer assembly  16 . 
         [0021]    While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims.