Abstract:
A vehicle comprises a plurality of motors operatively connected with one another. The vehicle is powered with the plurality of motors individually and in combination with one another to primarily operate each of the plurality of motors within a predetermine efficiency range.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/241,590 filed Sep. 11, 2009, the entire contents of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates, generally, to an electric motor for use with a hybrid vehicle, and more specifically, to an electric motor that can be combined with other motors to power a vehicle. 
       BACKGROUND 
       [0003]    Advancements in technology and the growing concern for environmentally efficient vehicles have led to the use of alternate fuel and power sources for vehicles. Electric vehicles or hybrid electric vehicles use electro mechanical devices (motors) to power the vehicle. In order to provide the required torque and power to operate the vehicle the motor must be designed to operate over a broad operating range. When a motor is chosen to act for an all purpose function, such as driving a vehicle, the motor needs to have the capacity for all load conditions, including the capacity to meet the maximum torque and power demands of the vehicle. 
         [0004]    However, vehicles do not require peak torque and power at all times of operation. During normal operating conditions there is excess torque and power available from the motor. Additionally, motors, like any power source, have certain efficiency ranges in which they achieve their optimal performance. Sizing the motor to provide the capacity for all load conditions results in an over-sized motor that must bear the inefficiency when not operating at the optimum range. Inefficiencies of the over-sized motor are most apparent when operating at low speed. At low operating speed the forces to overcome the mass of the rotor contributes to great inefficiencies. Another inefficiency from an oversized motor is, the centrifugal forces required to start and stop the motor requires excess power and depletes the available energy more than necessary. 
         [0005]    Additionally, vehicles are available in a variety of sizes and weights which results in additional variety in the motor capacity required among various vehicles. Therefore, the larger vehicles must default to larger and unique motors. The cost to design, manufacture and carry inventory on the variety of motors required results in cost inefficiencies as well. 
       SUMMARY 
       [0006]    A vehicle comprises a plurality of motors that are operatively connected with one another. The plurality of motors is operable to power the vehicle individually and in combination with one another. Each of the plurality of motors are generally identical to one another. Alternatively, the plurality of motors is operable to power the vehicle individually and in combination with one another such that each of the plurality of motors primarily operates in a predetermined efficiency range. 
         [0007]    A method of powering a vehicle comprises operatively connecting a plurality of motors with one another and powering the vehicle with the plurality of motors individually and in combination with one another to primarily operate each of the plurality of motors within a predetermined efficiency range. 
         [0008]    The above features and advantages, and other features and advantages of the present invention will be readily apparent from the following detailed description of the preferred embodiments and best modes for carrying out the present invention when taken in connection with the accompanying drawings and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic illustration of an electric vehicle having a first embodiment of a stackable motor of the present invention; 
           [0010]      FIG. 2  is a schematic illustration of an electric vehicle having a second embodiment of the stackable motor of the present invention; 
           [0011]      FIG. 3  is a schematic graph of the stackable motor output for the second embodiment of the vehicle shown in  FIG. 2 ; 
           [0012]      FIG. 4  is a schematic illustration of a third embodiment of the stackable motor for the vehicle of  FIG. 1 ; and 
           [0013]      FIG. 5  is a schematic illustration of a fourth embodiment of the stackable motor for the vehicle of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to the Figures, wherein like reference numbers refer to the same or similar components throughout the several views,  FIG. 1  schematically illustrates a vehicle  10  including at least one motor  12 , and a transmission  14 . The vehicle  10  may be any vehicle that utilizes an electric motor to provide the vehicle with drive, such as an electric vehicle, a hybrid electric vehicle, or a fuel cell vehicle. Therefore, in addition to the at least one motor  12  the vehicle  10  may also include an internal combustion engine  16 . 
         [0015]    In the embodiment shown there is a first motor  12 A and a second motor  12 B. The first motor  12 A and the second motor  12 B are the same size and capacity as one another. The first motor  12 A and the second motor  12 B are operatively connected to one another to drive the transmission  14 . In the embodiment shown the first motor  12 A and the second motor  12 B are coupled to one another. In this manner, the first motor  12 A and the second motor  12 B are stackable to provide the capacity required for the vehicle  10  while primarily operating within the efficiency ranges for the first motor  12 A and the second motor  12 B. Therefore, one large electric motor may be replaced by multiple smaller motors  12 . The first motor  12 A and the second motor  12 B may be any type of electromechanical device to provide power, such as an induction motor, permanent magnet machine, A/C or D/C motors, etc. 
         [0016]    The first motor  12 A and the second motor  12 B may be coupled together directly, through clutches or a solid shaft connection, or indirectly, such as a serpentine belt. Direct coupling of the first motor  12 A to the second motor  12 B would provide an efficient arrangement with few losses. Indirect coupling may provide a more flexible arrangement for packaging the first motor  12 A and the second motor  12 B within the vehicle  10 . One skilled in the art would be able to select the manner of coupling most suited for a particular vehicle  10 . Any number of generally identical motors,  12  may be combined or stacked to provide the capacity required by the vehicle  10 . 
         [0017]    The first motor  12 A acts as the primary motor and operates to drive the transmission  14  while the vehicle  10  is operating at steady speeds. The second motor  12 B acts as an additional power source and engages to drive the transmission  14  when additional operating loads are placed on the motors  12 , such as during accelerations of the vehicle  10 . The second motor  12 B would engage any time the operating loads exceed the capacity of the first motor  12 A. Alternatively, the second motor  12 B may be engaged prior to the capacity of the first motor  12 A and at any time when the first motor  12 A begins to operate outside of the desired efficiency range. In this manner the first motor  12 A and the second motor  12 B may both operate within their efficiency range for greater periods of time and the overall vehicle  10  efficiency will be increased. 
         [0018]    In the above embodiment, the first motor  12 A is the primary motor for the vehicle  10  and the second motor  12 B is used to provide additional power and torque when required by the vehicle  10 . Alternatively, the second motor  12 B may be the primary motor and the first motor  12 A may be used to provide additional power and torque. Additionally, the first motor  12 A and the second motor  12 B may alternately be the primary motor and the other would provide the additional power and torque. In this manner, even overall wear on both the first motor  12 A and the second motor  12 B may be maintained. 
         [0019]    Further, the primary motor  12 A or  12 B and the additional motor  12 B or  12 A may be engaged or disengaged to maintain operation within the efficiency ranges. The primary motor  12 A or  12 B and the additional motor  12 B or  12 A may also engage or disengage in cooperation with the shift strategy of the transmission  14  to maintain maximum efficiency of the vehicle  10 . In this manner, nontraditional shift strategies of the transmission  14  may be utilized in combination with the motors  12  to increase the efficiency of the vehicle  10 . 
         [0020]    Additionally, the first motor  12 A or the second motor  12 B may act as the primary motor in case of mechanical trouble of the other motor  12 A-B. In this instance the primary motor  12 A-B would not be able to meet the full capacity of the vehicle  10 . However, the vehicle  10  would operate in a restricted or limp-home mode but would allow the vehicle  10  operator to reach their destination. 
         [0021]      FIGS. 2-3  illustrate a second embodiment of the vehicle  110  including at least one motor  112 , and a transmission  114 . The vehicle  110  may be an electric vehicle or a hybrid electric vehicle  110 . Therefore, in addition to the at least one motor  112  the vehicle  110  may also include an internal combustion engine  116 . 
         [0022]    In the embodiment shown, there are four motors,  112 A,  112 B,  112 C,  112 D to drive the vehicle  110 . As explained above any number of motors,  112  may be combined to provide the capacity required by the vehicle  110 . In this manner one large electric motor may be replaced by multiple smaller motors  112 . 
         [0023]    The first through fourth motors  112 A-D are operatively connected to one another and may be coupled together by directly, through clutches, or indirectly, such as by a serpentine belt. Direct coupling of the first through fourth motors  112 A-D would provide an efficient arrangement with few losses. Indirect coupling may provide a more flexible arrangement for packaging the first through fourth motors  112 A-D within the vehicle  10 . One skilled in the art would be able to select the manner of coupling most suited for a particular vehicle  110 . 
         [0024]    One of the motors  112  may be designated as the primary motor  112 A and the other motors  112 B-D may provide additional power and torque as required by the vehicle 110 . When the capacity of the first motor  112 A is exceeded or when the first motor  112 A begins to operate outside the efficiency range, the additional motors  112 B-D may be engaged. The additional motors  112 B-D may each provide the same amount of additional power and torque. Alternatively, the additional motors  112 B-D may be engaged in an incremental manner. For example, the second motor  112 B may be engaged to assist the first motor  112 A when the capacity of the first motor  112 A is exceeded or when the first motor  112 A begins to operate outside the efficiency range. When the capacity of the first motor  112 A and the second motor  112 B are exceeded or when the first motor  112 A and the second motor  112 B begin to operate outside the efficiency ranges, then the third motor  112 C may be engaged. Likewise, the fourth motor  112 D would engage when the capacity/efficiency of the first through third motors  112 A-C are exceeded. Similar to the embodiment explained above, the motor  112 A-D which acts as the primary power source for the vehicle  10  may alternate among the first through fourth motors  112 A-D to maintain even overall wear on the first through fourth motors  112 A-D. 
         [0025]    Additionally, any one of the first through fourth motors  112 A-D may act as the primary motor in case of mechanical trouble of one of the other motors  112 A-D. For example, if the first motor  112 A is acting as the primary motor and incurs mechanical trouble the second motor  112 B may then be used as the primary motor and the first motor may be disengaged until the mechanical trouble can be corrected. In the instance of trouble for any of the motors  112 A-D then the motor  112 A-D chosen to be the primary motor and the additional operating motors  112 A-D would not be able to meet the full capacity of the vehicle  110 . However, the vehicle  110  would operate in a restricted or limp-home mode but would allow the vehicle  110  operator to reach their destination. 
         [0026]      FIG. 3  is a graph which illustrates how the output of the first through fourth motors  112 A-D may be combined to allow the first through fourth motors  112 A-D to primarily operate within their efficiency ranges while combining to provide the capacity required by the vehicle  110 . Phase  0  indicates the output of the first motor  112 A. Phase  1  indicates the output of the second motor  112 B as operating along with the first motor  112 A such that the torque output is increased. Phase  3  indicates the output of the motors when the first through third motors  112 A-C are operating together and Phase four indicates the output of all the motors  112 A-D operating at the same time. The efficiency range for the motors  112 A-D is indicated at area  120 . By adding the outputs of the motors  112 A-D together each of the motors  112 A-D each motor  112 A-D can continue to operate within the efficiency range  120  while providing an increase in the total output torque. 
         [0027]      FIG. 4  schematically illustrates a third embodiment of a vehicle  210  having a first motor  212 A and a second motor  212 B. The first motor  212 A and the second motor  212 B are coupled directly together. Direct coupling of the first motor  12 A to the second motor  12 B provides an efficient arrangement with few losses. The first motor  212 A has a first input member  222 A and a first output member  224 A. Likewise, the second motor  212 B has a second input member  222 B and a second output member  224 B. The first output member  224 B is connected to the second input member  224 A. In the embodiment shown, the first and second input members  222 A and  222 B are female input shafts and the first and second output members  224 A and  224 B are male output shaft. However, any arrangement of input members  222 A-B and output members  224 A-B that would mate together may be utilized. 
         [0028]    The first motor  212 A and the second motor  212 B are identical and have the same input members  222 A-B and output members  224 A-B. Additional motors (not shown) may be connected to the first and second motors  212 A-B and would have the same input members and output members. Therefore, any number of motors  212  may be connected in any order as required to provide the capacity of the vehicle  210 . 
         [0029]    In the embodiment shown in  FIG. 4 , the second motor  212 B is connected to the transmission  214  and acts as the primary motor to drive the vehicle  210  while operating at steady speeds. The first motor  212 A acts as an additional power source and engages to drive the vehicle  210  when additional operating loads are placed on the motors  212 A-B, such as during accelerations of the vehicle  110 . The first motor  212 A would engage any time the operating loads exceed the capacity of the second motor  212 B. Alternatively the first motor  212 A may be engaged prior to reaching the capacity of the second motor  212 B and at any time when the second motor  212 B begins to operate outside of the desired efficiency range. In this manner, the first motor  212 A and the second motor  212 B may both operate within their efficiency range for greater periods of time and the overall vehicle  210  efficiency will be increased. 
         [0030]    In the above embodiment, the second motor  212 B is the primary motor for the vehicle  210  and the first motor  212 A is used to provide additional power and torque when required by the vehicle  10 . Alternatively, the first motor  212 A may be the primary motor and the second motor  212 B may be used to provide additional power and torque. Additionally, the first motor  212 A and the second motor  212 B may alternately be the primary motor and the other would provide the additional power and torque. In this manner, even overall wear on both the first motor  212 A and the second motor  212 B may be maintained. The first motor  212 A has a first rotor  226 A and the second motor  212 B has a second motor  226 B. Due to the direct connection between the first motor  212 A and the second motor  212 B the rotor  226 A or  226 B of the additional motor  212 A or  212 B would continue to rotate while the primary motor  212 B or  212 A operates even though the additional motor  212 A or  212 B is not operating. 
         [0031]    Additionally, either the first motor  212 A or the second motor  212 B may act as the primary motor if case of mechanical trouble of the other motor  212 A-B. In this instance the primary motor  212 B or A would not be able to meet the full capacity of the vehicle  210 . However, the vehicle  210  would operate in a restricted or limp-home mode but would allow the vehicle  210  operator to reach their destination. 
         [0032]      FIG. 5  schematically illustrates a fourth embodiment of a vehicle  310  having a first motor  312 A and a second motor  312 B. The first motor  312 A has a first input member  322 A and a first output member  324 A. Likewise, the second motor  312 B has a second input member  322 B and a second output member  324 B. 
         [0033]    The first motor  312 A is connected to the second motor  312 B through a first clutch  328 A. That is, the first clutch  328 A has a first clutch input member  330 A and a first clutch output member  330 B. The first motor output member  324 A is connected to the first clutch input member  330 A and the first clutch output member  332 A is connected to the second motor input member  322 B. 
         [0034]    The second motor  312 B is connected to a transmission  314  for the vehicle  310  through a second clutch  328 B. That is, the second clutch  328 B has a second clutch input member  330 B and a second clutch output member  332 B. The second motor output member  324 B is connected to the second clutch input member  330 B and the second clutch output member  332 B is connected to the transmission  314 . 
         [0035]    The first motor  312 A, the second motor  312 B, the first clutch  328 A and the second clutch  328 B are generally identical and each have the same input members  322 A-B,  330 A-B and output members  324 A-B,  332 A-B as one another. Additional motors and clutches (not shown) may be connected to the first and second motors  312 A-B and the first and second clutches  328 A-B and would have the same input members and output members. Therefore, any number of motors  312  may be connected through the clutches  328 A-B as required to provide the capacity required by the vehicle  310 . 
         [0036]    In the embodiment shown, the first and second motor input members  322 A and  322 B are female input members and the first and second motor output members  324 A and  324 B are male output members. Likewise, the first and second clutch input members  330 A-B are female input members and the first and second clutch output members  332 A-B are male output members. However, any arrangement of input members  322 A-B,  330 A-B and output members  324 A-B,  332 A-B may be utilized which would allow the first and second motors  312 A-B to be connected through the first and second clutches  328 A-B 
         [0037]    In the embodiment shown, the second motor  312 B is connected through the second clutch  328 B to the transmission  314  and acts as the primary motor and to drive the vehicle  310  is operating at steady speeds. The first motor  312 A acts as an additional power source and engages to drive the vehicle  310  when additional operating loads are placed on the motors  312 A-B, such as during accelerations of the vehicle  110 . The first motor  312 A would engage any time the operating loads exceed the capacity of the second motor  312 B. Alternatively, the first motor  312 A may be engaged prior to reaching the capacity of the second motor  312 B and at any time when the second motor  312 B begins to operate outside of the desired efficiency range. In this manner, the first motor  312 A and the second motor  312 B may both operate within their efficiency range for greater periods of time and the overall vehicle  310  efficiency will be increased. 
         [0038]    The first motor  312 A has a first rotor  326 A and the second motor  312 B has a second motor  326 B. The first rotor  326 A does not rotate when the second motor  312 B is operating and the first motor  312 A is not operating. This is due to the first motor  312 A and the second motor  312 B being connected through the clutch  328 A which can be disengaged when the first motor  312 A is not operating. 
         [0039]    Additionally, the first motor  312 A or the second motor  312 B may act as the primary motor if case of mechanical trouble of the other motor  312 A or  312 B. In this instance the primary motor  312 B or  312 A would not be able to meet the full capacity of the vehicle  310 . However, the vehicle  310  would operate in a restricted or limp-home mode but would allow the vehicle  310  operator to reach their destination. 
         [0040]    In the embodiment described above the motors  12 ,  112 ,  212 ,  312  are described as being generally identical to one another. That is, the motors  12 ,  112 ,  212 ,  312  have the same general size, capacity and preferably configuration of one another. Alternatively, this may mean for a particular vehicle  10 ,  110 ,  210 ,  310  configuration the motors  12 ,  112 ,  212 ,  312  of that vehicle  10  are able to be used interchangeably with one another. 
         [0041]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.