Abstract:
An automobile comprising a continuously variable transmission (“CVT”) system including an acceleration input device, a CVT, and a processor. The acceleration input device generates acceleration input data indicating an amount of change in the acceleration input device, and a rate of change in the acceleration input device. The CVT includes a power source and a transmission output system. The power source operates at a transmission input speed, while the transmission output system operates at a transmission output speed. The transmission input speed over the transmission output speed comprises a gear ratio. The processor analyzes the acceleration input data to determine a target gear ratio. The processor can instruct the CVT to change the gear ratio to the target gear ratio at a rate corresponding to the rate of change in the acceleration input device.

Description:
BACKGROUND 
     1. Field 
     The present invention relates to a method and system for adaptive continuously variable transmission gear ratio control. 
     2. Description of the Related Art 
     Conventional automobiles containing conventional continuously variable transmission systems change gear ratios based on an amount of depression of an acceleration pedal as indicated by a user. The greater the depression of the acceleration pedal, the greater the gear ratio. Likewise, the less the depression of the acceleration pedal, the lower the gear ratio. The changing of the gear ratios can cause acceleration or deceleration of the automobile. 
     However, in certain situations the user of the automobile may wish to accelerate more quickly or decelerate more quickly. Yet, in other situations, the user of the automobile may not care if the automobile accelerates quickly or decelerates quickly. Conventional automobiles, however, do not distinguish between either situations, and instead change gear ratios based only on the amount of depression of the acceleration pedal, which results in the automobile changing gear ratios in a less responsive manner to the user. Furthermore, such changing of the gear ratios has the potential to be inefficient and unnecessarily consume fuel. 
     Thus, there is a need for a method and system for an adaptive continuously variable transmission gear ratio control which is more efficient and responsive to the user. 
     SUMMARY 
     The present invention relates to a method and system for an adaptive continuously variable transmission gear ratio control which is more efficient and more responsive to the user. In one embodiment, an automobile can include a continuously variable transmission (“CVT”) system including an acceleration input device, a CVT, and a processor. The acceleration input device can generate acceleration input data indicating not only an amount of change in the acceleration input device, but also a rate of change in the acceleration input device. 
     The CVT can include a power source and a transmission output system. The power source can operate at a transmission input speed, while the transmission output system can operate at a transmission output speed. The transmission input speed over the transmission output speed comprises a gear ratio. In one embodiment, the CVT can be any type of transmission which has a minimum gear ratio, a maximum gear ratio, and can infinitely change gear ratios between the minimum gear ratio and the maximum gear ratio. In another embodiment, the CVT can include an electric motor, a hydraulic pump, gears, belts or any other type of equipment which can allow the CVT to have the minimum gear ratio, the maximum gear ratio and infinitely change gear ratios between the minimum gear ratio and the maximum gear ratio. 
     The processor analyzes the acceleration input data to determine a target gear ratio and to determine a rate of change in the acceleration input data. The processor can also instruct the CVT to change the gear ratio to a target gear ratio, with a rate of change in the gear ratio corresponding to the rate of change in the acceleration input data. 
     Thus, the gear ratio changes based on the rate of change in the acceleration input data. Therefore, if the acceleration input data changes quickly, such as if the user is depressing the acceleration input unit quickly or the gear ratio is changed to the target gear ratio quickly. However, if the acceleration input data changes slowly, such as if the user is depressing the acceleration input unit slowly or the gear ratio is changed to the target gear ratio slowly. This can allow a quick acceleration when the user wishes to accelerate quickly and for fuel efficiency when the user does not care if he accelerates quickly. Thus, the present invention is more response to the user&#39;s intentions and can also expend fuel more efficiently. 
     In one embodiment, the present invention is a continuously variable transmission system including a continuously variable transmission operating at a gear ratio, an acceleration input device detecting acceleration input data, and a processor connected to the continuously variable transmission and the acceleration input device, the processor detecting a rate of change in the acceleration input data and changing the gear ratio based on the rate of change in the acceleration input data. 
     In another embodiment, the present invention is an automobile including a power source operating at a transmission input speed, a transmission output system operating at a transmission output speed, wherein the transmission input speed over the transmission output speed comprise the gear ratio, an acceleration input device detecting acceleration input data, and a processor connected to the power source, the transmission output system, and the acceleration input device, the processor determining a target gear ratio based on the acceleration input data, detecting a rate of change in the acceleration input data, and changing the gear ratio to match the target gear ratio based on the rate of change in the acceleration input data. 
     In yet another embodiment, the present invention is a method for varying a gear ratio of a continuously variable transmission system including operating a continuously variable transmission at a gear ratio, detecting acceleration input data, detecting a change in the acceleration input data, and changing the gear ratio at a rate based on the rate of change in the acceleration input data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, obstacles, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein: 
         FIG. 1  is an automobile including a continuously variable transmission system according to an embodiment of the present invention; 
         FIG. 2  depicts an acceleration input data graph according to an embodiment of the present invention; 
         FIG. 3  depicts gear ratios corresponding to various acceleration input data according to an embodiment of the present invention; and 
         FIG. 4  is a process of varying a gear ratio of a continuously variable transmission system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Apparatus, systems and methods that implement the embodiments of the various features of the present invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate some embodiments of the present invention and not to limit the scope of the present invention. Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. 
     As seen in  FIG. 1 , the present invention can include, for example, an automobile  100 . The automobile  100  can include, for example, a continuously variable transmission (“CVT”) system  102 . The automobile  100  can be, for example, an electric automobile, a hybrid automobile, a gasoline automobile, a natural gas automobile, an ethanol automobile, or any other type of motor or engine driven automobile. The CVT system  102  can include an acceleration input device  104 , a processor  112 , and a CVT  106 . 
     The acceleration input device  104  is connected to the processor  112  and can generate, for example, acceleration input data. The acceleration input device  104  can be, for example, an acceleration pedal and the acceleration input data can indicate, for example, a percent (%) application of the input device  104  and a rate of change in the percent (%) application of the acceleration input device  104 . The acceleration input device  104 , however, can be any type of device which receives acceleration input data indicating a user&#39;s desire to maintain a speed of the automobile  100 , decrease the speed of the automobile  100 , and/or increase the speed of the automobile  100 . 
     The CVT  106  is connected to the processor  112 . The CVT  106  includes, for example, a power source  108  and a transmission output system  110 . The power source  108  can be, for example, an engine, a motor, or any other type of system or object which can controllably move the automobile  100 . The power source  108  can operate at a transmission input speed. The transmission output system  110  can operate at a transmission output speed. 
     The transmission input speed over the transmission output speed comprises the gear ratio. Thus changes to the transmission input speed or the transmission output speed can affect the gear ratio. For example, when the transmission output speed remains constant, any increase in the transmission input speed results in an increase in the gear ratio. Likewise, when the transmission output speed remains constant, any decrease in the transmission input speed results in a decrease in the gear ratio. In the previous examples, when the transmission output speed remains constant, any change in the transmission input speed affects the gear ratio. However, as previously noted, the gear ratio can still be changed by changing the transmission input speed, even when the transmission output speed is not constant. In one embodiment, the gear ratio can also be changed by changing the transmission output speed and/or a combination of the transmission input speed and the transmission output speed. 
     The processor  112  is connected, for example, to the CVT  106  and/or the acceleration input device  104 . The processor  112  receives the acceleration input data, determines a target gear ratio, and adjusts the gear ratio in the CVT  106  to match the target gear ratio. Thus, if the target gear ratio is greater than the gear ratio, the processor  112  increases the gear ratio to match the target gear ratio. However, if the target gear ratio is smaller than the gear ratio, the processor  112  decreases the gear ratio to match the target gear ratio. 
     The processor  112  controls the rate of change in the gear ratio to match the target gear ratio. To determine the rate of change in the gear ratio, the processor  112  analyzes the acceleration input data and determines a rate of change in the acceleration input data. The rate of change in the acceleration input data indicates a rate of change in the acceleration input device  104 . The processor  112  sets the rate of change in the gear ratio corresponding to the rate of change in the acceleration input data. 
     Thus, if the rate of change in the acceleration input data is large, then the rate of change in the gear ratio is large. However, if the rate of change in the acceleration input data is small, then the rate of change in the gear ratio is small. Thus, if the user depresses the acceleration input device  104  quickly, the gear ratio changes quickly to reach the target gear ratio. However, if the user depresses the acceleration input device  104  slowly, the gear ratio changes slowly to reach the same target gear ratio. This can be seen, for example, in  FIG. 2  and  FIG. 3 . 
     In  FIG. 2 , curve  114  and curve  116  indicate acceleration input data depicting a percent (%) application of the acceleration input device  104  over time. Line  118  indicates the final value of the percent (%) application of the acceleration input device  104 . That is, line  118  represents the final position of the acceleration input device  104  when the user steps on the acceleration input device  104 . As can be seen, the user depresses the acceleration input device  104  by the same percentage, but at different rates. 
     In a first case, as represented by the curve  114 , the user depresses the acceleration input until the percent (%) application of the acceleration input device  104  reaches the final position of the acceleration input device  104  represented by line  118 . Once the percent (%) application of the acceleration input device  104  reaches the line  118 , the user has stopped depressing the acceleration input device  104 . In a second case, as represented by the curve  116 , the user depresses the acceleration input until the percent (%) application of the acceleration input device  104  reaches the final position of the acceleration input device  104  represented by line  118 , but at a faster rate than the first case. 
     In the first case, the percent (%) application of the acceleration input device  104  reaches the final position indicated by the line  118  at time t 2 . In the second case, the percent (%) application of the acceleration input device  104  reaches the final position indicated by the line  118  at time t 1 , which is less than the time t 2 . Thus, the user depresses the acceleration input device  104  at a faster rate in the second case than in the first case as seen by a comparison of the curves  114  and  116 . 
     The rate of change in the gear ratio corresponds to the rate of change in the percent (%) application of the acceleration input device  104 . In  FIG. 3 , the line  124  represents the target gear ratio. The curve  120  represents the change in the gear ratio corresponding to the first case with an application of the acceleration input device  104  represented by the curve  114  in  FIG. 2 . The curve  120  reaches the target gear ratio at time t 2 . The curve  122  represents the change in the gear ratio corresponding to the second case with an application of the acceleration input device  104  represented by the curve  116  in  FIG. 2 . The curve  122  reaches the target gear ratio at time t 1 . The time t 1  is less than the time t 2 . 
     As can be seen, the processor  112  changes the gear ratio at a rate corresponding to the rate of change in the percent (%) application of the acceleration input device  104 . Thus, in the curve  122 , since the corresponding application of the acceleration input device  104  is faster than in the curve  120 , the curve  122  reaches the target gear ratio at time t 1 , which is less than time t 2 . 
     By changing the gear ratio at a rate corresponding to the change in the percent (%) application of the acceleration input device  104 , the CVT  106  can be more responsive to the user of the automobile  100 . For example, if the user wants to accelerate the automobile  100  quickly, the user typically depresses the acceleration input device  104  more quickly. By changing the gear ratio quickly, the CVT  106  reaches the target gear ratio at a shorter period of time. This allows the CVT  106  to spend more time at the target gear ratio, which is higher than the gear ratio. By spending more time at the target gear ratio, the CVT  106  is providing more torque to the automobile  100  for a longer period of time, which translates to a quicker acceleration for the automobile  100 . 
     Likewise, if the user is nonchalant about accelerating and does not care if the automobile  100  accelerates quickly, or wants to accelerate the automobile  100  slowly, the user typically depresses the acceleration input device  104  slowly. By changing the gear ratio slowly, the CVT  106  reaches the target gear ratio at a longer period of time. This allows the CVT  106  to spend more time reaching the target gear ratio instead of at the target gear ratio, which is higher than the gear ratio. 
     By spending more time reaching the target gear ratio instead of being at the target gear ratio, the CVT  106  is providing more torque to the automobile  100  for a shorter period of time, which translates to a slower acceleration for the automobile  100 . This can also lead to a more efficient operation of the automobile  100  since the automobile  100  can consume less fuel when the user does not want to accelerate quickly. The examples described above are equally applicable to situations where the user wants to decelerate instead of accelerate. 
     In one embodiment, the present invention is a process of varying a gear ratio of a continuously variable transmission system as shown in  FIG. 4 . In Step S 402 , a CVT is operated at a gear ratio. For example, the CVT  106  can operate at a gear ratio, which is the transmission input speed of the power source  108  over the transmission output speed of the transmission output system  110 . In Step S 404 , acceleration input data is detected. For example, the acceleration input device  104  can detect acceleration input data. In Step S 406 , a change in the acceleration input data can be detected. For example, the processor  112  can analyze the acceleration input data and can determine changes in the acceleration input data. Furthermore, the processor  112  can determine a rate of change in the acceleration input data. 
     In Step S 408 , a target gear ratio is determined. For example, based on the acceleration input data, the processor  112  can determine the target gear ratio. In Step S 410 , the gear ratio can be changed to match the target gear ratio based on the acceleration input data. For example, the processor  112  can change the gear ratio at a rate corresponding to the rate of change in the acceleration input data. Thus, if the user is depressing the acceleration input device at a fast rate, the gear ratio will be changed to the target gear ratio at a fast rate. Likewise, if the user is depressing the acceleration input device at a slow rate, the gear ratio will be changed to the target gear ratio at a slow rate. 
     Those of ordinary skill would appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the examples disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Furthermore, the present invention can also be embodied on a machine readable medium causing a processor or computer to perform or execute certain functions. 
     To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed apparatus and methods. 
     The various illustrative logical blocks, units, modules, and circuits described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     The steps of a method or algorithm described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The steps of the method or algorithm may also be performed in an alternate order from those provided in the examples. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an Application Specific Integrated Circuit (ASIC). The ASIC may reside in a wireless modem. In the alternative, the processor and the storage medium may reside as discrete components in the wireless modem. 
     The previous description of the disclosed examples is provided to enable any person of ordinary skill in the art to make or use the disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosed method and apparatus. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.