Abstract:
A dual synchronization system of a manual transmission constructed in the dual set of a plurality of keys to be attached to the internal side of a synchronizer sleeve by a synchronizer ring, first and second key sets being positioned apart at a predetermined degree of angle along the circumferential direction of a synchronizer ring, wherein the first key set attaching the synchronizer ring close to a clutch gear at the initiation of synchronization and the second key set pushing the synchronizer ring close to the clutch gear after the completion of synchronization, thereby continuously maintaining the frictional force between the synchronizer ring and the clutch gear to achieve stable shifting feelings.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a synchronization system of a manual transmission, and more particularly to a dual synchronization system of a manual transmission having two sets of a plurality of keys for synchronization.  
           [0003]    2. Brief Description of the Prior Art  
           [0004]    In general, an automatic transmission is installed between clutch and driving axle, playing a role to change rotational force of an engine depending on a running condition of a vehicle and convey it to the driving axle and including a backward running apparatus for driving the vehicle backward.  
           [0005]    The aforementioned transmission is largely classified into an automatic transmission that automatically changes speed and a manual transmission that a driver directly manipulates shifting levers to four levels of forward driving or a level of backward driving. Specifically, the invention relates to a dual synchronization system of the manual transmission.  
           [0006]    [0006]FIG. 1 illustrates a synchronization system of a general manual transmission for an instance. As shown in the drawing, the synchronization system  1  includes a synchronizer sleeve  13 , synchronizer spring  15 , synchronizer hub  7 , synchronizer key  11  and synchronizer ring  35 , all of which are involved to overcome a difference in rotational speed between the synchronizer hub  7  and a clutch gear (not shown) in their connection or disconnection.  
           [0007]    In other words, the synchronizer hub  7  and the clutch gear having different rotational speeds will be connected together in the following steps. When the synchronizer sleeve  13  slides on the synchronizer hub  7  to a rotating direction of its rotational axle, the synchronizer key  11  closely attached into the synchronizer sleeve  13  with the synchronizer spring  15  pushes the synchronizer ring  35  tightly to the clutch gear. As a result, the synchronizer ring  35  and the clutch gear offset the difference in their rotational speeds for synchronization. At this time, the synchronizer sleeve  13  further proceeds to pass the synchronizer ring  35  and meshed with the clutch gear, so as to get the synchronizer hub  7  and the clutch gear to be in their direct connection.  
           [0008]    However, in the synchronization system  1  thus constructed, when the synchronizer sleeve  13  passes the synchronizer ring  35  and proceeds to the clutch gear after synchronization of the synchronizer ring  35 , the synchronizer sleeve  13  pushes the synchronizer key  11  attached to the internal side thereof with the synchronizer spring  15  inwards and over, so that the synchronizer key  11  can no longer provide force to push the synchronizer ring  35  tightly to the clutch gear.  
           [0009]    Therefore, at the aforementioned states, no force is involved to push the synchronizer ring  35  closely to the clutch gear while the synchronizer sleeve  13  passes the synchronizer ring  35  and meshes with the clutch gear. At this time, a breakdown of synchronization occurs to bring about a second nibble, which is a disadvantage in the conventional synchronization system.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an object of the present invention to solve the aforementioned problems and to provide a dual synchronization system of a manual transmission to prevent breakdown of synchronization and improve its shifting feeling of an auto vehicle.  
           [0011]    In order to accomplish the aforementioned object of the present invention, there is provided a dual synchronization system of a manual transmission constructed with first and second key sets respectively having a plurality of keys that are positioned apart at a predetermined degree of angle along the circumferential direction of a synchronizer ring, the first key set closely attaching the synchronizer ring to a clutch gear at the initiation of synchronization and the second key set pushing the synchronizer ring to the clutch gear after the completion of synchronization, thereby continuously keeping frictional force between the synchronizer ring and the clutch gear. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    For fuller understanding of the nature and object of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 is a perspective view for illustrating a general manual transmission;  
         [0014]    [0014]FIG. 2 is a cross-sectional view for illustrating a part where a first key set is installed in a dual synchronization system of a manual transmission in accordance with the present invention;  
         [0015]    [0015]FIG. 3 is a cross-sectional view for illustrating a part where a second key set is installed in a dual synchronization system of a manual transmission in accordance with the present invention;  
         [0016]    [0016]FIG. 4 is a layout view for illustrating the arrangement of a synchronizer ring and the first and second key sets of a manual transmission in accordance with the present invention; and  
         [0017]    [0017]FIG. 5 is a conceptual view for illustrating operations of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to accompanying drawings.  
         [0019]    [0019]FIG. 2 is a cross-sectional view for illustrating a part where a first key set is installed in a dual synchronization system of a manual transmission in accordance with the present invention, relating to the cross-sectional view cut along line II-II shown in FIG. 4. FIG. 3 is a cross-sectional view for illustrating a part where a second key set is installed in a dual synchronization system of a manual transmission in accordance with the present invention, relating to the cross-sectional view cut along line III-III shown in FIG. 4. FIG. 4 is a layout view for illustrating the arrangement of a synchronizer ring and the first and second key sets of a manual transmission in accordance with the present invention, and FIG. 5 is a conceptual view for illustrating operations of the present invention.  
         [0020]    As shown in the drawings, a dual synchronization system of the manual transmission is constructed with synchronizer sleeve  101 , synchronizer spring  102 , synchronizer hub  103 , first key set  104 - 1 , second key set  104 - 2  and synchronizer rings  105 - 1 ,  105 - 2 , and the operations of the dual synchronization system makes it possible to overcome a difference of rotational speeds between the synchronizer hub  103  and clutch gears  106 - 1 ,  106 - 2  for connection or disconnection therebetween.  
         [0021]    In other words, the main axle  107  of the clutch gear is installed to mesh the synchronizer hub  103  along spline for simultaneous rotations. A plurality of grooves  108  are radially formed at the external circumference of the synchronizer hub  103  for respectively arranging three keys of the first and second key sets at the interval of 120 degrees. Outside of the plurality of grooves  108 , the synchronizer sleeve  101  is coupled for moving to the direction of the axle. The keys of the first and second key sets  104 - 1 ,  104 - 2  are closely attached and supported at the internal side of the synchronizer sleeve  101  by the synchronizer spring  102 .  
         [0022]    On the other hand, as shown in FIGS. 2 and 3, speed gears  109 - 1 ,  109 - 2  are arranged at both sides of the synchronizer sleeve  101  without rotational interference of the main axle  107  for forming respective shifts, and the clutch gears  106 - 1 ,  106 - 2  having cone parts  110 - 1 ,  110 - 2  are integrally formed at one side of the speed gears  109 - 1 ,  109 - 2  for performing a synchronization by the friction generated by getting the synchronizer rings  105 - 1 ,  105 - 2  in contact with the cone parts  110 - 1 ,  110 - 2 .  
         [0023]    At this time, the synchronization means that the synchronizer rings  105 - 1 , 105 - 2  and clutch gears  106 - 1 ,  106 - 2  get to a state where they integrally rotate at an identical level of speed from another state where not at different levels of speed.  
         [0024]    In addition, the synchronizer rings  105 - 1 ,  105 - 2  have screw parts at their internal sides for increasing friction with the cone parts  110 - 1 ,  110 - 2  and a plurality of slots  111 - 1 ,  111 - 2  at the external sides for getting the ends of the keys of the first and second key sets  104 - 1 ,  104 - 2  positioned along the circumference thereof.  
         [0025]    At this time, the keys of the first and second key sets  104 - 1 ,  104 - 2  are alternatively arranged at a predetermined equal interval along the circumferential direction of the synchronizer rings  105 - 1 ,  105 - 2 . In the preferred embodiment of the present invention, three keys of the first and second key sets are respectively arranged as shown in FIG. 4.  
         [0026]    Therefore, those keys of the first and second key sets are installed at an angular interval of 120 degrees.  
         [0027]    On the other hand, a difference between FIGS. 2 and 3 is in that a concave part  112 - 2  at lower side of the synchronizer sleeve corresponding to the keys of the second key set  104 - 2  is formed longer than that  112 - 1  at the lower side of the synchronizer sleeve corresponding to the keys of the first key set  104 - 1 . Like this, if there is a difference in the length of the concave parts of the synchronizer sleeve  101 , when the synchronizer sleeve  101  moves to the axle, the keys of the first and second key sets  104 - 1 ,  104 - 2  are also moved to the axle by the synchronizer sleeve  101  at different points of time to thereby push the synchronizer rings  105 - 1 ,  105 - 2  toward the cone parts  110 - 1 ,  110 - 2  of the clutch gears  106 - 1 ,  106 - 2 .  
         [0028]    Operations of the synchronization system thus constructed will be described below. Speed gears  109 - 1 ,  109 - 2 , clutch gears  106 - 1 ,  106 - 2  and synchronizer rings  105 - 1 ,  105 - 2  are respectively assembled at both sides of the synchronizer sleeves  101  for forming different shifts, so as to make it possible to switch to a different shift level according to the operational direction of the synchronizer sleeve  101 . Hereinafter, for conveniences, the description will be made only about how shifting operations are made when the synchronizer sleeve  101  moving to the left functions with the speed gears  109 - 1 , clutch gear  106 - 1  and synchronizer ring  105 - 1  positioned at the left side of the drawing.  
         [0029]    When a driver manipulates a shift lever, the synchronizer sleeve  101  moves along the axial direction on the synchronizer hub  103 . At this time, the synchronizer sleeve  101  is pushed close to the cone part  110 - 1  of the clutch gear  106 - 1  connected to the speed gear  109 - 1  of a desired shift when the keys of the first and second key sets  104 - 1 ,  104 - 2  are pushed to the lateral wall of the synchronizer ring  105 - 1 .  
         [0030]    At this time, a mechanism where the synchronizer sleeve  101  moves the keys is as follows: if the protruded part of keys positioned to the internal side of the concave parts  112 - 1 ,  112 - 2  of the synchronizer sleeve  101  is pushed to the axial direction by the lateral wall of the concave parts  112 - 1 ,  112 - 2  to the point, where the keys cannot be pushed any longer, the keys transform the synchronizer spring  102  and are pushed to the internal side of the synchronizer sleeve  101 , allowing the continuous procession of the synchronizer sleeve  101 .  
         [0031]    As shown in the preferred embodiment of the present invention in FIG. 5, the operations of the mechanism described above will be separately performed at keys of the first and second key sets  104 - 1 ,  104 - 2 , and the aforementioned operations will be started one by one, respectively at the initiation and completion of synchronization.  
         [0032]    In other words, when the synchronizer sleeve  101  starts being moved at the initiation of synchronization, the keys of the first key set  104 - 1  just like those of the prior art play a role to eliminate the difference in the rotational speeds of the synchronizer ring  105 - 1  and clutch gear  106 - 1  by pushing the synchronizer ring  105 - 1  to the clutch gear  106 - 1  by the lateral wall of the concave part  112 - 1 , and those of the second key set  104 - 2  function after completion of synchronization, as described above, that is, when the synchronizer sleeve  101  pushes the keys of the first key set  104 - 1  away to the internal side. As the concave part  112 - 2  at the internal side of the synchronizer sleeve  101  corresponding to the keys of the second key set  104 - 2  is longer than that  112 - 1  corresponding to the keys of the first key set  104 - 1 , the lateral wall of the concave part  112 - 2  starts to get in contact with the keys of the second key set  104 - 2  when the keys of the first key set  104 - 1  starts to be pushed inwards and the keys of the second key set  104 - 2  push the synchronizer ring  105 - 1  close to the clutch gear  106 - 1  until the synchronizer sleeve  101  begins to be meshed with the clutch gear  106 - 1 , thereby continuously keeping the operational state of synchronization.  
         [0033]    Therefore, the synchronizer sleeve  101  starts to be moved by a driver&#39;s manipulation of the shift lever and maintains the stable state of synchronization by pushing the synchronizer ring  105 - 1  close to the clutch gear  106 - 1  from the initiation of synchronization when the synchronizer ring  105 - 1  starts to be put close to the clutch gear  106 - 1 , until the completion of synchronization when the synchronizer ring  105 - 1  gets to the same rotational speed as the clutch gear  106 - 1  and to the point of time when the synchronizer sleeve  101  is meshed with the clutch gear  106 - 1 , so as to prevent the breakdown of synchronization and improve shifting feelings with the stable shifting operations once the synchronization has been achieved.  
         [0034]    As described above, there is an advantage in the dual synchronization system of the present invention in that the keys of the system are made in a dual system to continuously maintain the once-formed state of synchronization, thereby achieving stable shifting operations and better shifting feelings of the manual transmission.