Abstract:
A synchronizer assembly for use in manual transmissions has enhanced lubrication and improved service life. The synchronizer assembly includes an outer, blocker ring, an intermediate ring and an inner ring. A plurality of circumferentially spaced apart radial holes in the intermediate and inner rings directs lubrication oil to the inner surfaces of both the intermediate ring and the blocker ring to reduce friction and enhance heat dissipation into the lubricating oil and away from the synchronizer.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/136,909, filed Mar. 23, 2015, which is hereby incorporated in its entirety herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to synchronizers for use in manual motor vehicle transmissions and more particularly to synchronizers for use in manual motor vehicle transmissions having enhanced lubrication and thus extended service life. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    Synchronizers are a necessary component of modern manual transmissions which were once referred to as synchromesh transmissions. Synchronizers are essentially clutches in themselves that reside between a shift collar and each gear on a shaft or countershaft which synchronize the about to be engaged gear with the shift collar so that the shift collar and gear can be easily, quickly and quietly coupled to transmit torque from, for example, the shaft, through the shift collar, through the gear and to another gear. 
         [0005]    Depending upon the speed differential between the shift collar and the selected gear, significant heat can be generated as the synchronizer slows the faster moving component or speeds the slower moving component. Additionally, if a particular shift is repeated within a short period of time, heat from one synchronization may not be dissipated before more heat is generated in the synchronizer by a second or third synchronization. This may readily occur with upshift and downshifts involving the same gear. 
         [0006]    It is apparent, therefore, that heat generation in manual transmission synchronizers can be significant and can lead to reduced service life of such components. The present invention is directed to enhancing lubrication of such synchronizers and improving their service life. 
       SUMMARY 
       [0007]    The present invention provides a synchronizer assembly for use in manual transmissions having enhanced lubrication and improved service life. The synchronizer assembly includes an outer, blocker ring, an intermediate ring and an inner ring. A plurality of circumferentially spaced apart radial holes in the intermediate and inner rings directs lubrication oil to the inner surfaces of both the intermediate ring and the blocker ring to reduce friction and enhance heat dissipation into the lubricating oil and away from the synchronizer. 
         [0008]    Thus it is an aspect of the present invention to provide a manual transmission synchronizer having enhanced lubrication and improved service life. 
         [0009]    It is a further aspect of the present invention to provide a manual transmission synchronizer having a plurality of radial lubrication holes in an inner ring. 
         [0010]    It is a still further aspect of the present invention to provide a manual transmission synchronizer having a plurality of radial lubrication holes in an intermediate ring. 
         [0011]    It is a still further aspect of the present invention to provide a manual transmission synchronizer having a plurality of radial lubrication holes in both an inner ring and an intermediate ring. 
         [0012]    It is a still further aspect of the present invention to provide a manual transmission synchronizer having a plurality of circumferentially spaced apart radial lubrication holes in both an inner ring and an intermediate ring. 
         [0013]    It is a still further aspect of the present invention to provide a manual transmission clutch having a synchronizer including a plurality of radial lubrication holes in both an inner ring and an intermediate ring. 
         [0014]    It is a still further aspect of the present invention to provide a manual transmission clutch having a synchronizer including a plurality of circumferentially spaced apart radial lubrication holes in both an inner ring and an intermediate ring. 
         [0015]    Further advantages, aspects 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 
         [0016]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0017]      FIG. 1  is a perspective view of a manual transmission synchronizer assembly, associated gears and shaft incorporating the present invention; 
           [0018]      FIG. 2  is a full sectional view of a manual transmission synchronizer assembly, associated gears and shaft incorporating the present invention; and 
           [0019]      FIG. 3  is a perspective view of a complete synchronizer assembly according to the present invention; 
           [0020]      FIG. 4  is a perspective view of the intermediate and inner rings of a synchronizer assembly according to the present invention, 
           [0021]      FIG. 5  is a perspective view of the intermediate ring of a synchronizer assembly according to the present invention; and 
           [0022]      FIG. 6  is a perspective view of the inner ring of a synchronizer assembly according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0024]    With reference now to  FIG. 1 , a portion of a manual transmission, namely a shaft, a pair of gears disposed on the shaft and a synchronizer assembly disposed on the shaft between the pair of gears, is illustrated and generally designated by the reference numeral  10 . The portion  10  of the manual transmission  10 , the shaft  12 , a first gear  14 , a second gear  16  and the synchronizer assembly  30  are typically one of several such assemblies disposed in parallel within the transmission (not illustrated) which provide, for example, first and second forward gears, third and fourth forward gears and higher forward gears and reverse depending upon the configuration of the transmission. 
         [0025]    With reference now to  FIG. 2 , the shaft  12  which may be an input shaft, a lay shaft or a countershaft includes an integrally formed gear  22  which is either driven by or drives other gears in the transmission, two pairs of roller bearing assemblies  24  that freely rotationally support the first and second gears  14  and  16 , respectively, a set of male or external splines  26  formed in the shaft  12  between the roller bearing assemblies  24  and a lubrication passageway  28  which provides transmission oil to various components of the transmission. 
         [0026]    The synchronizer assembly  30  includes a center hub  32  having internal or female splines  34  which are complementary to and engage the male splines  26  on the shaft  12 . The center hub  32 , in turn, includes male or external splines  36  which are complementary to and engage female or internal splines  38  on a shift sleeve or collar  40 . The shift sleeve or collar  40  includes an inner groove  42  into which one or preferably a plurality of detenting springs  44  reside. The detenting springs  44 , in accordance with conventional practice, provide resistance to moving the shift sleeve or collar  40  axially out of the position illustrated in  FIG. 2  and urge the sleeve or collar  40  into such position as it is approached from the left or right. The shift sleeve or collar  40  includes an outer peripheral channel or groove  46  which receives a shift fork  48  which translates the shift sleeve or collar  40  axially to the left or right. The shift fork  48  is coupled through a linkage to a shift knob or lever which is under the control of the vehicle operator (all not illustrated). 
         [0027]    The synchronizer assembly  30  is essentially symmetrical and includes left and right engagement rings  52 A and  52 B which are coupled to the respective, adjacent gears  14  and  16  by interengaging splines (not illustrated). The synchronizer assembly  30  also includes left and right blocker rings  54 A and  54 B, left and right intermediate rings  56 A and  56 B and left and right inner rings  58 A and  58 B. Accordingly, only one of the sides, the right side, including the right engagement ring  52 B, the right blocker ring  54 B, the right intermediate ring  56 B and the right inner ring  58 B will be described in further detail, it being understood that this explanation applies fully to the components of the left side of the synchronizer assembly  30  designated by the suffix letter A. 
         [0028]    Referring now to  FIGS. 2 and 3 , a complete right synchronizer assembly  30  is illustrated which includes the blocker ring  54 B which receives the intermediate ring  56 B which, in turn, receives the inner ring  58 B. The blocker ring  54 B includes peripheral discontinuous, i.e., circumferentially spaced apart, segments  62  of teeth  64  which have the same diameter and pitch as teeth  66  on the engagement ring  52 B. 
         [0029]    Referring now to  FIGS. 4 and 5 , the intermediate ring  56 B, which, as illustrated in  FIG. 3 , is seated within the blocker ring  54 B, includes a plurality of radially oriented, circumferentially spaced apart through lubrication apertures, holes or openings  72 . The lubrication openings  72  allow and encourage lubricating oil to flow into the interface between the outer surface of the intermediate ring  56 B and the inner surface of the blocking ring  54 B. While the number of openings  72  and their diameter may vary, for example, according to the diameter and width of the intermediate ring  56 B, a range of from eight to sixteen openings  72  has been found functional and between ten and fourteen is preferred. In a typical intermediate ring  56 B having a width of 7 mm. (0.2756 in.), a diameter of the apertures, holes or openings  72  of 1 mm. (0.0394 in.) has been found suitable but is subject to the caveat appearing below. The intermediate ring  56 B also includes a plurality, preferably three or six, axially extending, circumferentially equally spaced apart lugs or projections  74 . The lugs or projections  74  extend toward the center of the synchronizer assembly  30 . 
         [0030]    Referring now to  FIGS. 4 and 6 , the inner ring  58 B, which, as illustrated in  FIG. 4 , is seated within the intermediate ring  56 B, also includes a plurality of radially oriented, circumferentially spaced apart through lubrication apertures, holes or openings  76 . The lubrication openings  76  allow and encourage lubricating oil to flow into the interface between the outer surface of the inner ring  58 B and the inner surface of the intermediate ring  56 B. While the number of openings  76  and their diameter may vary, for example, according to the diameter and width of the inner ring  58 B, a range of from eight to sixteen openings  76  has been found functional and between ten and fourteen is preferred. In a typical inner ring  58 B having a width of 7 mm. (0.2756 in.), a diameter of the apertures, holes or openings  76  of 1 mm. (0.0394 in.) has been found suitable but is subject to the caveat appearing below. The inner ring  58 B also includes a plurality of axial slots or channels  78  on its outer surface which further assist distribution of lubrication. The inner ring  58 B also includes a plurality, preferably three, axially extending, circumferentially equally spaced apart lugs or projections  82 . The lugs or projections  82  extend away the center of the synchronizer assembly  30  in a direction opposite to that of the lugs or projections  74  on the intermediate ring  56 B. 
         [0031]    It will be appreciated that rotation of the inner rings  58 A and  58 B and intermediate rings  56 A and  56 B during operation and the centrifugal forces generated thereby significantly assist in the outward migration of lubricating oil which not only reduces friction between the rings thereby reducing heat generation and operating temperatures but also assists in carrying away and dissipating the heat that is generated resulting in improved synchronizer reliability and service life. While the lubrication holes or openings  72  in the intermediate rings  56 A and  56 B and the lubrication holes or openings  76  in the inner rings  58 A and  58 B enhance the lubrication characteristics of the synchronizer assembly  30 , they also introduce some local stress concentrations. Therefore, the strength of the rings  56 A,  56 B,  58 A and  58 B should be considered as a limiting factor with regard to the size and the number of holes or openings  72  and  76  placed in the intermediate rings  56 A and  56 B and the inner rings  58 A and  58 B, respectively. 
         [0032]    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.