Abstract:
A sliding centrifugal drive weight for use in an automatic transmission found in motor vehicles or watercrafts. The sliding centrifugal drive weight, which mainly consists of an outer friction shell and an inner core weight, comprises an upper inclined face in sliding contact with a ramp plate, a bottom surface in sliding contact with a movable drive pulley half, a left face, and a right wear resistant face. The sliding centrifugal drive weight is designed to eliminate abnormal wear, prevent reduction gear ratio deterioration, prolong the useful life of the transmission, and have the availability to adjust reduction gear ratios as well as driving performance. At the same time, the sliding centrifugal drive weight is also adapted to compensate wear automatically, to adjust by itself to move further outward in a movable drive pulley half, make the vehicle reach a higher maximum vehicle speed.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an automatic continuous variable transmission. More particularly, the invention relates to a centrifugal roller weight used in an automatic continuous variable transmission or the like found in motor vehicles, boats or watercrafts, or auxiliary mechanisms. Each centrifugal roller weight comprising a core weight and an outer cover made of wear-resistant resin is provided between a ramp plate and a movable drive pulley half of a drive pulley in the automatic transmission mentioned above. Upon a centrifugal force, the centrifugal roller weights move radially in the drive pulley to continuously change the width of the grooves of the drive pulley and a driven pulley while the drive pulley and driven pulley are mounted around by an endless belt, so as to change the vehicle speed continuously. 
   2. Description of the Prior Art 
   A conventional automatic continuous variable transmission (i.e., CVT)  1  of a motor vehicle is illustrated in  FIG. 1  and it comprises a drive pulley  2  proximate to an engine  12 , a driven pulley  3  at a rear axle, and an endless trapezoid-section belt  9  (i.e., V-belt  9 ) rotatably interconnected with the drive pulley  2  and the driven pulley  3 . In the operation, a piston  8  is activated when the engine  12  starts. Next, a rotary shaft  10  rotates to revolve the drive pulley  2 . A plurality of centrifugal weight rollers  6  (i.e., weight roller  6 ) in a movable drive pulley half  4  move radially outward upon a centrifugal force acting thereon. A ramp plate  7  is fixed; hence, the movable drive pulley half  4  moves toward a stationary drive pulley half  5  due to an opposite reaction, and forces exerted on sides of the V-belt  9  push the V-belt  9  of the drive pulley  2  to move outward. Thus, the effective diameter of the V-belt  9  of the drive pulley  2  increases and, at the same time, the V-belt  9  of the driven pulley  3  moves toward the rotary shaft  10  and the effective diameter of the V-belt  9  of the driven pulley  3  decreases. As the revolution of engine changes, the centrifugal force acting on the weight roller  6  is changed. Thus, the distance between the movable drive pulley half  4  and the stationary drive pulley half  5  is changed. As a result, the continuous change of effective diameters of V-belts  9  of the drive pulley  2  and the driven pulley  3  changes the speed of vehicle. Such a conventional continuous variable transmission  1  of motor vehicle is disclosed in U.S. Pat. No. 4,925,432. The shape of the weight roller  6  in the movable drive pulley half  4  is spherical (see U.S. Pat. No. 2,986,043) or cylindrical (see U.S. Pat. No. 4,925,432). 
   The weight roller  6  is at a lowest position in the movable drive pulley half  4  when the revolution of engine is lower than a predetermined value or centrifugal force acting on the weight roller  6  is very small (see  FIG. 2 ). At this position, the effective diameter (2h R0 ) of the V-belt  9  in the drive pulley  2  is a minimum and the effective diameter of the V-belt  9  in the driven pulley  3  is a maximum. The transmission  1  is in a low gear status when the weight roller  6  is at its lowest position (see  FIG. 2 ). 
   The revolution of the drive pulley  2  is higher than that of the driven pulley  3  when the motor vehicle starts. For example, the drive pulley  2  may rotate three times while the driven pulley  3  rotates once. This means a reduction gear ratio 3:1 in low gear status, when the vehicle speed is slow but the engine has a large torque. 
   As the revolution of engine increases, the centrifugal force acting on the weight roller  6  increases correspondingly. While weight rollers  6  gradually move radially outward, the effective diameter of the V-belt  9  in the drive pulley  2  increases and the effective diameter of the V-belt  9  in the driven pulley  3  decreases correspondingly. This continuous changing of the effective diameter of the V-belt of the drive pulley  2  and that of the driven pulley  3  shows the continuous gearshifting of the automatic transmission. 
   The weight roller  6  is at a highest position in the movable drive pulley half  4  (see  FIG. 3 ). At this position, the effective diameter ( 2 h R ) of the V-belt  9  of the drive pulley  2  is a maximum and the effective diameter of the V-belt  9  of the driven pulley  3  is a minimum. The transmission  1  is in a high gear status when the weight roller  6  is at its highest position (see  FIG. 3 ). At this position, the revolution of the drive pulley  2  is lower than that of the driven pulley  3 . For example, the drive pulley  2  may rotate 0.9 times while the driven pulley  3  rotates once. This means a reduction gear ratio 0.9:1 in high gear status, when the vehicle speed is fast but the engine has a small torque. 
   From the mechanism of prior art, we can understand that if the sizes and angles of the drive pulley  2 , the driven pulley  3 , and other related parts are fixed, and sizes of weight rollers  6  are fixed, then the lowest position (see  FIG. 2 ) and highest position (see  FIG. 3 ) of the weight roller  6  in the movable drive pulley half  4  are fixed. Thus, reduction gear ratios of low gear status and high gear status in the transmission are unchangeably fixed. However, when the weight rollers  6  wear after a period of time of use, reduction gear ratios of low gear status and high gear status then deteriorate undesirably. This in turn adversely affects a gearshifting performance of the motor vehicle. 
   In the prior art it is typically to decrease weight of the weight roller  6  for increasing driving power. In this arrangement, the required revolution of the engine for a clutch  11  to engage and for the vehicle to start will increase to a value larger than the predetermined required value. Thus, the vehicle can start powerfully. However, the centrifugal force in this arrangement is therefore not large enough, and the effective diameter (2h R ) of the V-belt  9  of the drive pulley  2  is decreased, so the maximum vehicle speed is decreased, due to lighter weight rollers  6 . On the contrary, increasing weight of the weight rollers  6  will increase the centrifugal force and decrease the required revolution of the engine for the clutch  11  to engage and start the vehicle. Thus, the vehicle starts relatively weakly. However, because of heavier weight rollers  6 , the centrifugal force is larger and the effective diameter (2h R ) of the V-belt  9  of the drive pulley  2  is increased, and therefore the maximum vehicle speed is increased. 
   In the prior art it is also found that, when the weight rollers  6  are at its highest position (see  FIG. 3 ), surfaces of the weight rollers  6  contacted with the ramp plate  7  may easily be worn or scraped due to low precision of the ramp plate  7 . As those stated above, when the weight rollers  6  are worn and their sizes become smaller, the distance that the movable drive pulley half  4  can move is shorter and the effective diameter (2h R ) of the V-belt  9  of the drive pulley  2  is decreased. As a result, reduction gear ratios of low gear status and high gear status of the transmission will then deteriorate significantly. 
   From those stated above we understand that, in the said centrifugal automatic transmission, using weight rollers  6  in the movable drive pulley half  4  of the drive pulley  2  has the following disadvantages: (1) Surface of the weight roller  6  usually wear abnormally when the weight roller  6  is at its highest position (see  FIG. 3 ). Thus, reduction gear ratios of low gear status and high gear status can deteriorate significantly. (2) Changing weight of the weight roller  6  merely cannot increase both the initial acceleration and maximum vehicle speed of the motor vehicle simultaneously. (3) If sizes and angles of the drive pulley  2  and the driven pulley  3  are retained unchanged, it is not possible to use means of weight rollers  6  to adjust reduction gear ratio of low gear status or high gear status, and it is not easy to adjust driving performance either. Thus, the need for improvement exists. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide an improved weight roller, which we hereby call it sliding centrifugal drive weight  60 , that can not only eliminate the disadvantages of roller weight  6  of the prior art, but also increase the adjustability and performance of a centrifugal automatic transmission. 
   This sliding centrifugal drive weight  60  will be installed in an automatic transmission which comprises a drive pulley  2  including a movable drive pulley half  4 , a stationary drive pulley half  5 , and a ramp plate  7 , a movable driven pulley  3 , an endless V-belt  9  having one end rotatably fitted around a groove confined by the drive pulley  2  and the other end rotatably fitted around a groove confined by the driven pulley  3 , and a plurality of said sliding centrifugal drive weights  60  mounted between the ramp plate  7  and the ramp  13  of the movable drive pulley half  4 . In a rotational movement of the movable drive pulley half  4 , each said sliding centrifugal drive weight  60  is adapted to slidingly move radially outward along the ramp  13  of the movable drive pulley half  4  upon a centrifugal force acting thereon, while the movable drive pulley half  4  moves axially toward the stationary drive pulley half  5  so as to change sizes of the grooves of the drive pulley  2  and of the driven pulley  3 . Both effective diameter of the V-belt  9  of the drive pulley  2  and the driven pulley  3  is therefore changed, and thereby effecting a smooth gearshifting. Each said sliding centrifugal drive weight  60  consists of an outer friction shell  65  formed of durable self-lubricated plastics and an inner core weight  64  usually formed of metal; and said sliding centrifugal drive weight  60  comprises an upper inclined face  61  in sliding contact with the inner surface  14  of the ramp plate  7 , a bottom surface  62  in sliding contact with the ramp  13  of the movable drive pulley half  4 , a left face  67  (the left face being the side of the sliding centrifugal drive weight  60  which is nearest the rotary shaft  10 ) which is urged against a left side inner wall  16  of the movable drive pulley half  4  when said sliding centrifugal drive weight  60  is at its lowest position in the movable drive pulley half  4 , and a right wear resistant face  66  which is almost not in contact with a right side inner wall  15  of the movable drive pulley half  4  when said sliding centrifugal drive weight  60  is at its highest position in the movable drive pulley half  4 ; that is, said sliding centrifugal drive weight is designed to have a feature of d 2 &gt;d 3 , and is adapted to compensate the wear automatically and to adjust by itself to move further outward and obtain a higher maximum vehicle speed. A plurality of distance parameters including d 1 , d 2 , d 3 , and d 4  with respect to the upper inclined face  61 , said bottom surface  62 , said left face  67 , and said right wear resistant face  66  are defined wherein d 1  is the distance from the center O of said sliding centrifugal drive weight  60  to the left face  67  of said sliding centrifugal drive weight  60  measured in a direction normal to the rotary shaft  10 , d 2  is the distance from the center O of said sliding centrifugal drive weight  60  to the upper inclined face  61  of the sliding centrifugal drive weight  60  measured in a direction normal to the surface of the inclined face  61 , d 3  is the distance from the center O of the sliding centrifugal drive weight  60  to the right wear resistant face  66  of said sliding centrifugal drive weight  60  measured in a direction normal to the rotary shaft  10 , and d 4  is the distance from the center O of said sliding centrifugal drive weight  60  to the nearest point on the bottom surface  62  of said sliding centrifugal drive weight  60 . 
   The above and other objects, features and advantages of the present invention will become apparent from the following detailed description along with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view in part section of a conventional automatic continuous variable transmission (a.k.a. CVT); 
       FIG. 2  is a sectional view of a portion of the movable drive pulley half shown in  FIG. 1  where. the centrifugal weight roller therein is at its lowest position in a low gear status; 
       FIG. 3  is a view similar to  FIG. 2  where the centrifugal weight roller is at its highest position in a high gear status; 
       FIG. 4  is a sectional view of a portion of a movable drive pulley half wherein the sliding centrifugal drive weight, whose bottom surface is arcuate according to a first preferred embodiment of the present invention, is at its lowest position in a low gear status; 
       FIG. 5  is a view similar to  FIG. 4  where the sliding centrifugal drive weight according to the first preferred embodiment is at its highest position in a high gear status; 
       FIGS. 6 and 7  are perspective views of a sliding centrifugal drive weight according to the present invention; 
       FIG. 8  is a sectional view of the sliding centrifugal drive weight shown in  FIG. 6  according to the present invention; 
       FIG. 9  is an exploded view of the automatic CVT incorporating the sliding centrifugal drive weights and the drive pulley according to the present invention; 
       FIG. 10  is a plot of drive pulley revolutions (rpm, i.e., revolution per minute) versus driven pulley revolutions (rpm) for comparing the performance of the sliding centrifugal drive weight of a first preferred configuration of the present invention with that of the conventional centrifugal weight roller of the prior art in a CVT; 
       FIG. 11  is a plot of engine revolutions (rpm) versus vehicle speed (km/hr) for comparing the performance of the sliding centrifugal drive weight of a second preferred configuration of the present invention with that of the conventional centrifugal weight roller of the prior art in a full load acceleration N/V curve; 
       FIG. 12  is a table showing the data recorded in the CVT properties comparison of the sliding centrifugal drive weight of a first preferred configuration of the present invention and the conventional centrifugal weight roller of the prior art; 
       FIG. 13  is a table showing the data recorded in the CVT properties comparison of the sliding centrifugal drive weight of a second preferred configuration of the present invention and the conventional centrifugal weight roller of the prior art; 
       FIG. 14  is a table showing the data recorded in the CVT properties comparison of the sliding centrifugal drive weight of a third preferred configuration of the present invention and the conventional centrifugal weight roller of the prior art; 
       FIG. 15  is a table showing the data recorded in the CVT properties comparison of the sliding centrifugal drive weight of a fourth preferred configuration of the present invention and the conventional centrifugal weight roller of the prior art; 
       FIG. 16  is a table showing the data recorded in the CVT properties comparison of the sliding centrifugal drive weight of a fifth preferred configuration of the preferred invention and the conventional centrifugal weight roller of the prior art; 
       FIG. 17  is a sectional view of a portion of a movable drive pulley wherein the sliding centrifugal drive weight, whose bottom surface has an inclined flat surface according to a second preferred embodiment of the present invention, is at its lowest position in a low gear status; 
       FIG. 18  is a view similar to  FIG. 17  where the sliding centrifugal drive weight is at its highest position in a high gear status; and 
       FIG. 19  is a perspective view of a sliding centrifugal drive weight according to a third preferred embodiment of the present invention where one or a plurality of oil recesses are formed on its outer friction shell. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 4 ,  5 ,  6 ,  7 ,  8 , and  9 , a sliding centrifugal drive weight  60  according to the present invention for automatic transmission of a motor vehicle in accordance with a first preferred embodiment of the present invention comprises an outer friction shell  65  formed of durable self-lubricated plastics and an inner core weight  64  usually formed of metal. Said sliding centrifugal drive weight  60  comprises an upper inclined face  61  in sliding contact with an inner surface  14  of a ramp plate  7 , a bottom surface  62  in sliding contact with the ramp  13  of a movable drive pulley half  4 , a left face  67  urged against a left side inner wall  16  of the movable drive pulley half  4  when said sliding centrifugal drive weight  60  is at its. lowest position in the movable drive pulley half  4  ( FIG. 4 ), and a right wear resistant face  66  that almost does not contact with a right side inner wall  15  of the movable drive pulley half  4  even if said sliding centrifugal drive weight  60  is at its highest position in the movable drive pulley half  4 ; that is, said sliding centrifugal drive weight is designed to have a feature of d 2 &gt;d 3 , and is adapted to compensate the wear automatically and to adjust by itself to move further outward to obtain a higher maximum vehicle speed ( FIG. 5 ). 
   Definitions of a number of distance parameters with respect to said upper inclined face  61 , said bottom surface  62 , said left face  67 , and said right wear resistant face  66  are detailed below ( FIGS. 4 ,  5 , and  8 ) in which d 1  means a radial distance from the center point O to a point (shown as H) on a self-adjustment portion  63  of said left face  67  measured in a direction normal to the rotary shaft  10 , d 2  means a radial distance from the center point O to a point (shown as D) on said upper inclined face  61  measured in a direction normal to the surface of the inclined face  61 , d 3  means a radial distance from the center point O to a point (shown as F) on said right wear resistant face  66  measured in a direction normal to the rotary shaft  10 , and d 4  means a radial distance from the center point O to a nearest point (shown as G) on said bottom surface  62 . 
   Said sliding centrifugal drive weight  60  of the invention has a self-adjustment characteristic when d 2 &gt;d 3 . That is, a gearshifting performance of the transmission is not affected when said sliding centrifugal drive weight  60  according to the present invention has a minor wear (as detailed later in preferred configuration  11 ). Moreover, said sliding centrifugal drive weight  60  of the invention is adapted to enable said movable drive pulley half  4  to move a further out distance axially, the V-belt  9  to have a longer effective diameter (2h s ), and the motor vehicle to run faster (i.e., maximum vehicle speed increased). 
   Said sliding centrifugal drive weight  60  according to the present invention thus has a number of following advantages as compared with the conventional centrifugal weight roller  6  of prior art. (1) No abnormal wear occurs, and reduction gear ratio in a high gear status does not deteriorate when said sliding centrifugal drive weight  60  slides to a highest point ( FIG. 5 ). (2) The size and shapes of said sliding centrifugal drive weight  60  can be specially designed, so that said sliding centrifugal drive weights  60  at a same weight can cause a motor vehicle to have both an increased acceleration when starting off, and a faster acceleration to reach a higher maximum vehicle speed. (3) Said sliding centrifugal drive weights  60  can be specially designed to adjust reduction gear ratio of low gear status and high gear status in the transmission, respectively or simultaneously, without modifying sizes or angles of the movable drive pulley half  4  and the ramp plate  7 . Thus, it is easy to adjust the driving performance. 
   In addition, it is also found that it is not easy to obtain a precise ramp plate  7  due to punching, and thus an inclined angle of the ramp plate  7  is not always matched to that of the upper inclined face  61  (i.e., the ramp plate  7  is not aligned with the upper inclined face  61 ). Therefore, a self-adjustment portion  63  on said left face  67  is formed. When said sliding centrifugal drive weight  60  is placed between the movable drive pulley half  4  and the inner surface  14  of the ramp plate  7 , and the self-adjustment portion  63  of said left face  67  is urged against the left side inner wall  16  of the movable drive pulley half  4 , said sliding centrifugal drive weight  60  is adapted to adjust itself by pivoting about said self-adjustment portion  63  for aligning the upper inclined face  61  with the inner surface  14  of the ramp plate  7 , and therefore to obtain a maximum contact area therebetween. As a result, the movable drive pulley half  4  can slide smoother. 
   Said sliding centrifugal drive weight  60  according to the first preferred embodiment of the present invention will be described in detail in a number of preferred configurations below by referring to  FIGS. 4 ,  5 , and  10  to  16 . 
   Preferred Configuration I 
   In this configuration (see  FIGS. 10 and 12 ), the sliding centrifugal drive weight  60 &#39;s specifications are that d 1 =d 2 =d 4 =r and d 3 &lt;r. Said sliding centrifugal drive weight  60  is at a same lowest position in the movable drive pulley half  4  ( FIG. 4 ) as that of the conventional centrifugal weight roller  6  of the prior art shown in  FIG. 2 . That is, the diameter 2h S0  of V-belt according to this preferred configuration is equal to the diameter 2h R0  of V-belt of the prior art. As the revolution of the engine increases, the centrifugal force increases to a maximum. Because of d 3 &lt;r, the right wear resistant face  66  does not contact with the right side inner wall  15  of the movable drive pulley half  4 , and therefore, said sliding centrifugal drive weight  60  can continue to slide further outward a distance equal to r-d 3 . Thus, the side pressure exerted on the V-belt  9  of the drive pulley  2  is larger, and so the effective diameter of the V-belt  9  in the drive pulley  2  is larger than the effective diameter of the V-belt when using conventional centrifugal weight roller  6  of the prior art; that is, 2h S  in  FIG. 5  is larger than 2h R  in  FIG. 3 . By utilizing the sliding centrifugal drive weight  60  according to this preferred configuration, a motor vehicle can have a same initial acceleration, but reach a higher maximum vehicle speed while the revolution of the engine at the maximum vehicle speed is rather lower (see  FIGS. 10 and 12 ); that is, more fuel-saving. 
   Both the sliding centrifugal drive weight  60  according to this preferred configuration and the conventional centrifugal weight roller  6  of the prior art provide a same reduction gear ratio (2.60 as shown in  FIG. 12 ) in low gear status, but the reduction gear ratio in high gear status changes (from 0.85 to 0.77 as shown in  FIG. 12 ) when using the sliding centrifugal drive weight  60  according to this preferred configuration. That is, a higher maximum vehicle speed is obtained at a rather lower revolution of the engine. 
   Preferred Configuration II 
   In this configuration (see  FIGS. 11 and 13 ), the sliding centrifugal drive weight  60 &#39;s specifications are that d 1 =d 4 =r, d 2 &lt;r, and d 3 &lt;r. The lowest position (low gear status,  FIG. 4 ) of said sliding centrifugal drive weight  60  this preferred configuration is lower than that of the conventional weight roller  6  shown in  FIG. 2 ; that is, 2h S0  in  FIG. 4  is smaller than 2h R0  in  FIG. 2 . Thus, a higher revolution of the engine is required for a motor vehicle to start off, and a higher revolution of the engine means the initial torque is larger than that of the conventional centrifugal weight roller  6  of the prior art. Also, because of d 3 &lt;r, diameter 2h S  in  FIG. 5  is longer than diameter 2h R  in  FIG. 3 . Therefore, by utilizing the sliding centrifugal drive weight  60  according to this preferred configuration, a motor vehicle can extend its reduction gear ratio range (from a range of 2.83˜0.95 to a range of 3.00˜0.85, as shown in  FIG. 13 ). That is, the start-off is more powerful, and the maximum vehicle speed is higher while more fuel-saving (see  FIGS. 11 and 13 ). In this preferred configuration, it is also found that even though the sliding centrifugal drive weight  60  may wear after a period of time (i.e., A R &gt;A S  as shown in  FIG. 13 ), the sliding centrifugal drive weight  60  can adjust itself automatically, and therefore the maximum effective diameter of the V-belt will not be changed, and the performance of the motor vehicle in high speed will not be adversely affected. 
   Preferred Configuration III 
   In this configuration (see.  FIG. 14 ), the sliding centrifugal drive weight  60 &#39;s specifications are that d 1 =d 3 =d 4 =r and d 2 &gt;r. It is found that 2h S0  in  FIG. 4  is larger than 2h R0  in  FIG. 2  by comparing said sliding centrifugal drive weight  60  according to the present invention with the conventional centrifugal weight roller  6  of the prior art. That is, a motor vehicle can start off at a lower revolution of the engine. Also, because of d 2 &gt;r, an effective diameter of V-belt in the drive pulley  2  is increased and the maximum vehicle speed is higher when said sliding centrifugal drive weight  60  slides to its highest position (see  FIG. 14 ). By utilizing the sliding centrifugal drive weight  60  according to this preferred configuration, a motor vehicle can reduce its reduction gear ratio of low gear status (from 2.7 to 2.52, as shown in  FIG. 14 ); that is, start-off is smoother. Further, reduction gear ratio of high gear status can also be reduced (from 0.87 to 0.81, as shown in  FIG. 14 ) so the maximum vehicle speed is higher and the motor vehicle is more fuel-saving. 
   Preferred Configuration IV 
   In this configuration (see  FIG. 15 ), the sliding centrifugal drive weight  60 &#39;s specifications are that d 1 =d 4 =r, d 2 &gt;r, and d 3 &lt;r. By comparing said sliding centrifugal drive weight  60  according to the present invention with the conventional centrifugal weight roller  6  of the prior art, it is found that h S0  in  FIG. 4  is larger than h R0  in  FIG. 2 ; that is, a motor vehicle can start off at a lower revolution of the engine; i.e., the start-off is smoother. In addition, by comparing  FIG. 5  with  FIG. 3 , it is also found that the sliding centrifugal drive weight  60  according to the present invention moves a distance longer than that the conventional centrifugal weight roller  6  of the prior art does, by a value of r-d 3 . Thus, the effective diameter of the V-belt in the drive pulley  2  is increased; i.e., 2h S  in  FIG. 5  is larger than 2h R  in  FIG. 3 . As a result, the motor vehicle has a higher maximum vehicle speed (see  FIG. 15 ). By utilizing said sliding centrifugal drive weight  60  according to this preferred configuration, a motor vehicle can change its reduction gear ratio range (from a range of 2.69˜0.87 to a range of 2.57˜0.79, as shown in  FIG. 15 ); and this means the start-off is smoother, the revolution of the engine at start-off is lower, and the maximum vehicle speed is higher while more fuel-saving. 
   Preferred Configuration V 
   In this configuration (see  FIG. 16 ), the sliding centrifugal drive weight  60 &#39;s specifications are that d 1 =d 4 =r, d 2 &lt;r, and d 3 &lt;r. By comparing  FIG. 4  with  FIG. 2 , h S0  of this preferred configuration is smaller; while by comparing  FIG. 5  with  FIG. 3 , h S  according to this configuration is larger. Thus, by utilizing the sliding centrifugal drive weight  60  according to this configuration, a higher revolution of the engine is required for a motor vehicle to start off, and this means the torque at start-off is larger and the acceleration to a higher maximum vehicle speed is faster. For example, the acceleration time from 0 km to 100 km is decreased from 28.50 second to 25.41 second (see  FIG. 16 ). 
   According to the discussion of the preferred configurations, it is concluded that said sliding centrifugal drive weight  60  according to the present invention has many advantages that the conventional centrifugal weight roller  6  of the prior art does not have. Referring to  FIGS. 17 and 18 , the ramp of a movable drive pulley half  4  may be an inclined plane surface (i.e., ramp  13 A), and therefore according to a second embodiment of the present invention, the relevant bottom surface can be an inclined flat surface (i.e., bottom surface  62 A). Hence, the purposes of prolonging the useful life of said sliding centrifugal drive weight  60 A, making the gearshifting smoother, and increasing maximum vehicle speed can all be achieved. 
   Referring to  FIG. 19 , a sliding centrifugal drive weight  60  according to a third preferred embodiment of the present invention is illustrated, where one or a plurality of oil recesses  68  are formed on the outer friction shell for said sliding centrifugal drive weight  60  to further decrease the friction force and increase the agility during sliding movement.. 
   While the invention herein disclosed has been described by means of specific embodiments and configurations, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.