Abstract:
A shift system related to an improved continuously variable transmission (CVT) may include a power output assembly, a power input assembly, a collar assembly, and a connecting assembly to connect the power output assembly and power input assembly. The shift system is advantageous because it employs only gears and hydraulics for the transmission of power, which can be used in any torque scenario, from low-torque to heavy-duty scenarios such as large passenger automobiles, large trucks and heavy-duty machinery. Furthermore, there is no need to use additional energy to keep the transmission “tight enough” to engage and to prevent any “slipping,” and the overall efficiency of power transmission would be increased.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present invention is a continuation-in-part (CIP) application of Ser. No. 14/859,302 filed on Sep. 20, 2015 now pending, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a shift system for vehicles, and more particularly to a shift system related to an improved continuously variable transmission (CVT) with a simple structure, which is more durable and can be used to generate higher torque than conventional CVTs. 
       BACKGROUND OF THE INVENTION 
       [0003]    Generally speaking, automatic transmissions are essentially modulating converters that stepwise or steplessly independently change the present transmission ratio as a function of current or expected operating conditions, such as partial load, thrust, and ambient parameters such as temperature, air pressure, and humidity. Included in that group are modulating converters that are based on electric, pneumatic, hydrodynamic, or hydrostatic principles, or a combination of those principles. 
         [0004]    A continuously variable transmission (CVT) normally includes a first shaft which can receive torque from a prime mover, a second shaft which is or can be parallel with the first shaft, an adjustable pulley or sheave on each of the two shafts, and an endless flexible element (such as a chain or a belt and hereinafter referred to as chain) trained over the two pulleys to transmit torque from the first shaft to the second shaft when the first shaft is driven by the prime mover. The two pulleys are adjustable and, to this end, each pulley comprises a first conical flange, which is affixed to the respective shaft, and a second conical flange which is rotatable with the first flange and is movable axially relative to the respective shaft toward and away from the respective first flange. Such adjustability of the pulleys enables the chain to move one of its looped portions radially inwardly toward one of the shafts while its other looped portion moves radially outwardly and away from the other shaft, or vice versa. 
         [0005]    Continuously variable transmissions (CVTs) are often preferred over automatic transmissions, which employ a hydrokinetic torque converter in combination with a so-called bypass or lockup clutch. The reason is that the continuously variable transmission provides a greater comfort to the occupant or occupants of the motor vehicle because the shifts into different gear ratios invariably take place gradually without any appreciable shocks. Moreover, the utilization of a continuously variable transmission in the power train entails substantial savings in fuel requirements of the motor vehicle. 
         [0006]    However, due to the physical limitations of continuously variable transmissions using the “cone-pulley” concept or a belt/chain driven system, conventional CVTs can only be used for low torque scenarios, such as small passenger vehicles and light duty machinery. Furthermore, the cones or belt/chains of a CVT must be kept tight in order to supply enough friction to be able to successfully transfer power and to prevent “slipping.” This energy that is used to keep the cones and belt/chains tight is effectively another form of wasting energy and thus reducing overall efficiency. 
         [0007]    Moreover, in conventional CVTs, there is a “lag” time from when the gas pedal is depressed to when the car accelerates, which is also due to the physical limitations of the conventional CVT system of cone-pulley or belt/chains resulting in slower acceleration and insufficient torque. Also, conventional CVTs have the issues of noise, vibration and harshness. And since the structure of conventional CVTs is complicated, the reliability and durability thereof are decreased. Therefore, there remains a need for an improved shift system to overcome the problems stated above. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to provide a shift system related to an improved continuously variable transmission (CVT) that employs only gears and hydraulics for the transmission of power, which can be used in any torque scenario, from low-torque to heavy-duty scenarios such as large passenger automobiles, large trucks and heavy-duty machinery. 
         [0009]    It is another object of the present invention to provide a shift system related to an improved CVT that employs only gears and hydraulics for the transmission of power, so there is no need to use additional energy to keep the transmission “tight enough” to engage and to prevent any “slipping,” and the overall efficiency of power transmission would be increased. 
         [0010]    It is still another object of the present invention to provide a shift system related to an improved CVT that employs only gears and hydraulics for the transmission of power, so the transmission of the power is instant and does not suffer from the “lag” in acceleration to improve the control, efficiency and safety of the transmission system. 
         [0011]    It is still another object of the present invention to provide a shift system related to an improved CVT that employs only gears and hydraulics for the transmission of power, to eliminate the issues of noise, vibration and harshness associated with acceleration in conventional CVTs. 
         [0012]    It is a further object of the present invention to provide a shift system related to an improved CVT with a rather simple structure to be more reliable and durable, and the manufacturing costs can be significantly reduced. 
         [0013]    It is still a further object of the present invention to provide a shift system related to an environmental friendly CVT that can be set in the most suitable and efficient gear ratio, regardless of speed and condition, to reduce energy consumption. 
         [0014]    It is still a further object of the present invention to provide a shift system related to an improved CVT that employs only gears and hydraulics for the transmission of power that can be used for situations such as auto racing or mountain climbing because of its capability of instantaneous and quite acceleration. 
         [0015]    Various embodiments are illustrated in the figures and description provided herein. It should be understood, however, that the subject invention is not limited to the specific embodiments illustrated in the figures and specifically described herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic view of the shift system related to the improved continuously variable transmission (CVT) in the present invention. 
           [0017]      FIG. 2  is schematic view of the power output assembly in the present invention. 
           [0018]      FIG. 3  is a schematic view of the main rod and freewheels of the power output assembly in the present invention. 
           [0019]      FIG. 4  is a schematic view of the first and second gears and output gear of the power output assembly in the present invention. 
           [0020]      FIG. 5  is a schematic view of the collar assembly in the present invention. 
           [0021]      FIG. 6  is a schematic view of the power input assembly when the stretchers open up on the rotating arm to achieve the goal of high speed and low torque in the present invention. 
           [0022]      FIG. 7  is a schematic view of power input assembly when the stretchers move toward each other on the rotating arm achieve the goal of high torque and low speed in the present invention. 
           [0023]      FIG. 8  illustrates the parameter R in the present invention. 
           [0024]      FIG. 9  is a schematic view of the shift system related to the improved continuously variable transmission in the present invention when the rotating arm is parallel to the connecting rod. 
           [0025]      FIG. 10  is a schematic view of the shift system related to the improved continuously variable transmission in the present invention when the rotating arm is rotating to be parallel to the connecting rod. 
           [0026]      FIG. 11  is a schematic view of the shift system related to the improved continuously variable transmission in the present invention when the rotating arm is rotating 180 degrees from  FIG. 9 . 
           [0027]      FIG. 12  is a schematic view of the shift system related to the improved continuously variable transmission in the present invention when the rotating arm is rotating 270 degrees from  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The detailed description set forth below is intended as a description of the presently exemplary device provided in accordance with aspects of the present invention and is not intended to represent the only forms in which the present invention may be prepared or utilized. It is to be understood, rather, that the same or equivalent functions and components may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. 
         [0029]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices and materials similar or equivalent to those described can be used in the practice or testing of the invention, the exemplary methods, devices and materials are now described. 
         [0030]    All publications mentioned are incorporated by reference for the purpose of describing and disclosing, for example, the designs and methodologies that are described in the publications that might be used in connection with the presently described invention. The publications listed or discussed above, below and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. 
         [0031]    As used in the description herein and throughout the claims that follow, the meaning of “a”, an, and the includes reference to the plural unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the terms “comprise or comprising”, “include or including”, “have or having”, “contain or containing” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. As used in the description herein and throughout the claims that follow, the meaning of in includes in and on unless the context clearly dictates otherwise. 
         [0032]    It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0033]    It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
         [0034]    In one aspect, as shown in  FIGS. 1 to 3 , a shift system may include a power output assembly  100 , a power input assembly  200 , a collar assembly  300 , and a connecting assembly  400  to connect the power output assembly  100  and power input assembly  200 . In one embodiment, the shift system relates to a continuously variable transmission (CVT). The power output assembly  100  may include a first freewheel  1  coupled with a first gear  3  through a first shaft  7  and a second freewheel  2  coupled with a second gear  4  through a second shaft  8 . In one embodiment, the first freewheel  1  can be engaged with a main rod rack  10  on a top portion of a main rod  9 , while the second freewheel  2  can be engaged with the main rod  10  on a bottom portion of the main rod  9 . 
         [0035]    The main rod  9  is pivotally connected with a connecting rod  11  through a pivoting hinge  13  to form a pivoting mechanism  12 , so when power is generated by the power input assembly  200 , the power can be used to drive the connecting rod  11  through the connecting assembly  400 . In one embodiment, the main rod  9  moves toward a direction  15  as shown in  FIGS. 1 to 3 , and the main rod  10  engages with the first freewheel  1  and second freewheel  2  in a “rack and pinion” manner. Meanwhile, the second freewheel  2  rotates in a clock-wise manner as well as the second gear  4  through the second shaft  8 , and second gear  4  is configured to engage with at least one output gear  5  with an output shaft  6  to drive the output gear  5  to rotate in a counter clock-wise manner. The input gear  5  also engages with the first gear  3  to drive the first gear  3  to rotate in a clock-wise manner as well as the first freewheel  1 , however, when the main rod  9  moves toward direction  15 , the first freewheel  1  is supposed to rotate in the counter clock-wise manner. Since two different momentums to rotate in different directions apply to freewheel  1  simultaneously, freewheel  1  may become idle. It is noted that the main rod  9  is configured to slide with a plurality of sliding wheels  31  along a rail  17  on each sides of the main rod  9 . 
         [0036]    In another embodiment, the main rod  9  moves toward a direction  14  as shown in  FIGS. 1 to 3 , and the main rod  10  engages with the first freewheel  1  and second freewheel  2  in a “rack and pinion” manner. At the present stage, the first freewheel  1  rotates in a clock-wise manner as well as the first gear  3  through the first shaft  7 , and first gear  3  is configured to engage with at least one output gear  5  with an output shaft  6  to drive the output gear  5  to rotate in a counter clock-wise manner. The input gear  5  also engages with the second gear  4  to drive the second gear  4  to rotate in a clock-wise manner as well as the second freewheel  2 , however, when the main rod  9  moves toward direction  14 , the second freewheel  2  is supposed to rotate in the counter clock-wise manner. Since two different momentums to rotate in different directions apply to freewheel  2  simultaneously, freewheel  2  may become idle. 
         [0037]    It is noted that regardless of the traveling direction of the main rod  9 , the first gear  3  and second gear  4  always rotate in a clock-wise manner, and the output gear  5  always rotates in a counter clock-wise manner as shown in  FIG. 4 . The power can then be transferred out through the output shaft  6  in a counter clock-wise manner as well. 
         [0038]    Still referring to  FIG. 1 , the power input assembly  200  may include an input gear  29 , an input shaft  30  and a power source  40 . In one embodiment, the input gear  29  engages with a reduction gear  28 . One end of a main rotating shaft  21  is inserted to the center of the reduction gear  28 , and the other end thereof is connected with a rotating arm  18 , so when the rotating arm  18  can be driven by the reduction gear  28  through the main rotating shaft  21 . 
         [0039]    The power input assembly  200  may further include a hydraulic cylinder  27  coupled with a hydraulic positioning rod  22 , and the movement of the hydraulic cylinder  27  is managed by a control unit  33 , and the positioning rod  22  is connected to an end plate  25 . As shown in  FIG. 5 , the power input assembly  200  may have a collar assembly  300 , which may include a front collar  26 , a middle collar  34 , a back collar  35  and a sliding collar  36 . The sliding collar  36  is configured to slide and rotate on the main rotating shaft  21 , and the front collar  26  and back collar  35  are both coupled with the sliding collar  36 , so the three collars ( 26 ,  35 ,  36 ) can rotate as one unit on the main rotating shaft  21 . It is noted that the middle collar  34  is a non-rotating collar and is sandwiched by the front collar  26  and back collar  35 , and the middle collar  34  can also slide on the main rotating shaft  21 . The sliding collar  36  is configured to slide reciprocally on the main rotating shaft  21  because of the middle collar  34  connected to the end plate  25  that is moved by the hydraulic cylinder  27 . 
         [0040]    The power input assembly  200  may also include a first stretcher  19  is connected to an upper flange  24 ′ (on a sliding sleeve  20 ) on one end and to an upper portion  24  of the sliding collar  36  on the other end; while a second stretcher  19 ′ is connected to a bottom flange  23 ′ (on a sliding sleeve  20 ′) on one end and to a lower portion  23  of the sliding collar  36  on the other end. In one embodiment, the stretchers ( 19 ,  19 ′) are arranged in a V-shaped configuration as shown in  FIG. 1 . In another embodiment, the power input assembly  200  may include a pump  39  to provide oil to the hydraulic cylinder  27  and the control unit  33  through hydraulic oil pipes  32  and  38 . 
         [0041]    In an exemplary embodiment, when the hydraulic cylinder  27  moves towards the rotating arm  18 , it pushes the end plate  25  through the hydraulic positioning rod  22 , and further pushes the sliding collar  36  towards the rotating arm  18 . Meanwhile, since the stretchers ( 19 ,  19 ′) are pivotally connected to the upper and lower portion ( 24 ,  23 ) of the sliding collar  36  as well as the upper and lower portions of the flanges ( 24 ′,  23 ′), the sliding sleeves  20  and  20 ′ are then driven to move up and down respectively on the rotating arm  18  as shown in  FIG. 6 . At the present stage, the distance between the stretchers ( 19 ,  19 ′) on the rotating arm  18  increases, which is similar to an “up-shift” in a vehicle transmission having a higher speed but lower torque. 
         [0042]    On the other hand, when the hydraulic cylinder  27  retracts to pull back the end plate  25  away from the rotating arm  18 , the sliding collar  36  is also pulled back away from the rotating arm  18  to further drive the stretchers  19  and  19 ′ to move closes to each other on the rotating arm  18  as shown in  FIG. 7 . At the present stage, the distance between the stretchers ( 19 ,  19 ′) on the rotating arm  18  decreases, which is similar to a “down-shift” in a vehicle transmission having a lower speed but higher torque. 
         [0043]    Referring to  FIG. 8 , a parameter R can be defined as R x /R 0 , wherein R x  is variable indicating the distance between the middle portion of the rotating arm  18  and the position of the upper (or lower) flange, and R 0  is the radius of the freewheel  1  or  2 . As discussed above, when the hydraulic cylinder  27  moves towards the rotating arm  18 , the distance of the stretchers  19  and  19 ′ on the rotating arm  18  increases, namely R x  increases as shown in  FIG. 8 . Assuming R 0  is a constant, we can conclude that the higher the parameter R is, the higher speed and lower torque the transmission can provide. On the contrary, when the parameter R is lower, it indicates that the speed is lower but the torque is higher. 
         [0044]    The connecting assembly  400  may include the rotating arm  18 , the upper flange  24 ′ on the sliding sleeve  20 , the lower flange  23 ′ on the sliding sleeve  20 ′, a balancing pin  37  and a crankpin  16  extending from the opposite side of the upper flange  24 ′. The crankpin  16  is pivotally connected to the connecting rod  11 , so the power generated from the power input assembly  200  can be transmitted to the power output assembly  100 . 
         [0045]      FIGS. 9 to 12  shows how the power is transmitted through the improved CVT from the power input assembly  200  to the power output assembly  100 . The rotating arm  18  starts with a zero degree which is parallel to the connecting rod  11 , and when the power starts to kick in from the power input assembly  200 , the main rotating shaft  21  is driven to rotate the rotating arm  18  to  90  degrees which is perpendicular to the main rotating shaft  21 , then 180 degrees and 270 degrees to complete the entire power transmission cycle. During the power transmission cycle, the connecting rod  11  is driven to move the move the main rod  9  to drive the freewheels  1  and  2 , and further the output gear/shaft  5  and  6  as discussed above. 
         [0046]    Comparing with conventional CVTs, the present invention is advantageous because the improved continuously variable transmission (CVT) in the present invention employs only gears and hydraulics for the transmission of power. More specifically, the speed and torque of can be managed by the stretchers  19  and  19 ′ by their opening on the rotating arm  18  which is controlled by the hydraulic cylinder  27 , which does not need to use additional energy to keep the transmission “tight enough” to engage and to prevent any “slipping,” and the overall efficiency of power transmission would be increased. 
         [0047]    Having described the invention by the description and illustrations above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Accordingly, the invention is not to be considered as limited by the foregoing description, but includes any equivalents.