Abstract:
Methods and systems are provided that involve or include a transmission. During one of the methods, a motor is operated based on speed data to synchronize a first rotor of the transmission with a second rotor of the transmission, where the speed data is indicative of speeds of the first and the second rotors. The synchronized first and second rotors are engaged with one another to transfer torque from the motor to the output.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to a transmission and, more particularly, to methods and systems for shifting gears of a transmission. 
     2. Background Information 
     A modern automobile typically includes a transmission that transfers mechanical energy from a motor to components of a drive train. A modern automobile also typically includes at least one clutch and/or a torque converter, which allows the transmission to shift gears without damaging the gears as they engage or disengage one another. Such a clutch and/or torque converter, however, may increase the complexity, cost, weight and size of the automobile. 
     There is a need in the art for improved methods and systems for shifting gears of a transmission. 
     SUMMARY OF THE DISCLOSURE 
     Methods and systems are provided that involve or include a shiftable transmission. During a first of the methods, a motor is operated based on speed data to synchronize a first rotor (e.g., a gear) of the transmission with a second rotor (e.g., another gear) of the transmission, where the speed data is indicative of speeds of the first and the second rotors. The synchronized first and second rotors are engaged with one another to transfer torque from the motor to the output. During a second of the methods, the motor is operated based on torque data to substantially unload the first rotor, where the torque data is indicative of a torque to which the first rotor is subjected. The unloaded first rotor is disengaged from the second rotor to decouple the motor from the output. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description will be better understood when read in conjunction with the appended drawings, in which there is shown one or more embodiments of the present disclosure. It should be understood, however, that the various embodiments of the present disclosure are not limited to the precise arrangements and instrumentalities shown in the drawings. 
         FIG. 1  is a block diagram of a power system configured with a load; 
         FIG. 2  is a block diagram of sensors with a transmission in neutral; 
         FIG. 3  is a block diagram of the sensors with the transmission of  FIG. 2  in first gear; 
         FIG. 4  is a block diagram of the sensors with the transmission of  FIG. 2  in second gear; 
         FIG. 5  is a flow diagram of a method involving the power system of  FIG. 1 ; and 
         FIG. 6  is a block diagram of the sensors with an alternate embodiment transmission; 
         FIG. 7  is a block diagram of the sensors with another alternate embodiment transmission in first gear; and 
         FIG. 8  is a block diagram of the sensors with the transmission of  FIG. 7  in second gear. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a power system  20  configured with a load  22 . The power system  20  and/or the load  22  may be included in a land, water and/or air based vehicle such as, for example, an automobile, a truck, a motorcycle, a train, a tractor, a ship, a submarine, an aircraft, or a space craft. Alternatively, the power system  20  and/or the load  22  may be included in an autonomous mobile robot, a crane, a conveyor system, or any other type of consumer, industrial and/or military equipment. For ease of description, however, the power system  20  and the load  22  of  FIG. 1  are described below as being included in an automobile, which may be an electric automobile, a hybrid automobile or a gasoline/diesel powered automobile. 
     The load  22  is connected to the power system  20  by a shaft  24 , or any other type of power transfer device(s). The load  22  may be configured as or otherwise include one or more components of a drive train for the automobile. The load  22 , for example, may include one or more drive wheels  26  that are connected to the shaft  24  through a differential assembly  28  and one or more axles  30 . In other embodiments, however, the load  22  may be configured as or otherwise include a propeller, a winch, a pump, an electric generator, or any other device(s) that may be mechanically powered (e.g., driven) by the power system  20 . 
     The power system  20  includes a motor  32 , a transmission  34  and a control system  36 . The motor  32  may be configured as an electric motor that converts electrical energy into mechanical energy; e.g., torque. The electric motor may receive the electrical energy from a power storage device such as a battery. The electric motor may also or alternatively receive the electrical energy from a generator that may include, for example, one or more fuel cells and/or one or more solar panels, each of which may include an array of solar photovoltaic cells. Alternatively, the motor  32  may be configured as an internal combustion engine or a gas turbine engine that converts chemical energy into mechanical energy. Still alternatively, the motor  32  may be configured as a steam, hydraulic or pneumatic system that converts fluid energy to mechanical energy. The present invention, however, is not limited to any particular motor types or configurations. 
     The transmission  34  is connected to the motor  32  by a shaft  38 , or any other type of power transfer device(s). The transmission  34  is connected to the load  22  by the shaft  24 , or any other type of power transfer device(s). 
       FIGS. 2-4  illustrate an exemplary embodiment of the transmission  34 . The transmission  34  is configured to selectively transfer mechanical energy (e.g., torque) from the motor  32  to the load  22  (see  FIG. 1 ). The transmission  34  includes a plurality of gears  40 - 46  (e.g., rotors), an input shaft  48  (e.g., an input), a lay shaft  50  and an output shaft  52  (e.g., an output). 
     One or more of the gears  40 - 45  may each be configured as a spur gear, or a helical gear. Each gear  40 - 45  of  FIGS. 2-4 , for example, includes a plurality of teeth  54  arranged around and connected to a circumferential periphery of a circular gear body. One of more of the gears  44  and  45  may also each be configured as a crown-type gear. Each gear  44  and  45  of  FIGS. 2-4 , for example, includes a plurality of additional teeth  56  (or grooves) arranged around an axis of the gear body, and connected to (or extending into) a side of the gear body. 
     The gear  46  may be configured as a crown-type gear. The gear  46  of  FIGS. 2-4 , for example, includes a plurality of teeth  58  (or grooves) arranged around an axis of a gear body, and connected to (or extending into) a side of the gear body. The gear  46  also includes a plurality of additional teeth  60  (or grooves) arranged around the axis, and connected to (or extending into) another opposite side of the gear body. 
     The gear  40  is mounted on as well as axially and rotatably fixed to the input shaft  48 . Each of the gears  41 - 43  is mounted on as well as axially and rotatably fixed to the lay shaft  50 . Each of the gears  44  and  45  is rotatably mounted on and axially fixed to the output shaft  52 . A bushing or a bearing, for example, may be disposed between each respective gear  44 ,  45  and the output shaft  52 , which allows the gear  44 ,  45  to rotate relative to the output shaft  52 . One or more of the teeth  54  of the gear  40  are meshed with one or more of the teeth  54  of the gear  41 . One or more of the teeth  54  of the gear  42  are meshed with one or more of the teeth  54  of the gear  44 . One or more of the teeth  54  of the gear  43  are meshed with one or more of the teeth  54  of the gear  45 . 
     The gear  46  is slidably mounted on and rotatably fixed to the output shaft  52  between the gears  44  and  45 . The gear  46 , for example, may be further configured as a collar that mates with axially extending splines on the output shaft  52 . In this manner, a shift linkage  62  may slide the gear along the output shaft  52  to various positions including: a neutral position (see  FIG. 2 ), a first engaged position (see  FIG. 3 ), and a second engaged position (see  FIG. 4 ). 
     In the neutral position of  FIG. 2 , the transmission  34  may be referred to as being “out-of-gear” or “in neutral”. The gear  46 , for example, is located about midway between and does not contact the gears  44  and  45 . The input shaft  48  and the lay shaft  50  therefore may rotate without rotating the output shaft  52 . Thus, in the neutral position, the transmission  34  does not transfer mechanical energy from the motor  32  to the load  22 . 
     In the first engaged position of  FIG. 3 , the transmission  34  may be referred to as being “in-gear”; e.g., in first gear. The gear  46 , for example, axially engages the gear  44 . More particularly, the teeth  58  of the gear  46  are meshed with the teeth  56  of the gear  44 . Rotation of the input shaft  48  and the lay shaft  50  therefore may rotate the output shaft  52  at a first rotational speed. Thus, in the first engaged position, the transmission  34  transfers mechanical energy from the motor  32  to the load  22 . 
     In the second engaged position of  FIG. 4 , the transmission  34  may also be referred to as being “in-gear”; e.g., in second gear. The gear  46 , for example, axially engages the gear  45 . More particularly, the teeth  60  of the gear  46  are meshed with the teeth  56  of the gear  45 . Rotation of the input shaft  48  and the lay shaft  50  therefore may rotate the output shaft  52  at a second rotational speed that is different (e.g., faster) than the first rotational speed. Thus, in the second engaged position, the transmission  34  transfers mechanical energy from the motor  32  to the load  22 . 
     Referring again to  FIG. 1 , the control system  36  includes a sensor system  64  and a controller  66 . The sensor system  64  includes an input speed sensor  68 , an output speed sensor  70  and a torque sensor  72 . Each of these sensors  68 ,  70  and  72  may be configured as a contact sensor (e.g., an electro-mechanical sensor), or alternatively a non-contact sensor (e.g., a laser or proximity sensor). 
     Referring to  FIG. 2 , the input speed sensor  68  is arranged adjacent and contacts (or may be proximate) the input shaft  48 . The input speed sensor  68  is configured to monitor rotation of the input shaft  48 . The input speed sensor  68  is also configured to generate input speed data indicative of, for example, the rotational and/or tangential speeds of the input shaft  48 . In addition, since the lay shaft  50  and the gears  40 - 45  turn with the input shaft  48 , the input speed data is also indicative of the rotational and/or tangential speeds of the lay shaft  50  and the gears  40 - 45 . Of course, in other embodiments, the input speed sensor  68  may alternatively be configured to directly monitor and generate data indicative of the rotational and/or tangential speeds of the lay shaft  50  or one of the gears  40 - 45 . 
     The output speed sensor  70  is arranged adjacent and contacts (or may be proximate) the output shaft  52 . The output speed sensor  70  is configured to monitor rotation of the output shaft  52 . The output speed sensor  70  is also configured to generate output speed data indicative of, for example, the rotational and/or tangential speeds of the output shaft  52 . In addition, since the gear  46  turns with the output shaft  52 , the output speed data is also indicative of the rotational and/or tangential speeds of the gear  46 . Of course, in other embodiments, the output speed sensor  70  may alternatively be configured to directly monitor and generate data indicative of the rotational and/or tangential speeds of the gear  46 . 
     The torque sensor  72  is arranged adjacent and contacts (or may be proximate) the input shaft  48 . The torque sensor  72  may be configured as a load cell that may monitor stress and/or strain on or within the input shaft  48 . Based on the monitored stress and/or strain, the torque sensor  72  is also configured to generate torque data indicative of, for example, a torque to which the input shaft  48  is subjected. In addition, since the lay shaft  50  and the gears  40 - 45  turn with the input shaft  48 , the torque data is also indicative of the torques to which the lay shaft  50  and the gears  40 - 45  are subjected. Of course, in other embodiments, the torque sensor  72  may alternatively be configured to directly monitor and generate data indicative of the torque to which the lay shaft  50  or one of the gears  40 - 45  is subjected. 
     Referring to  FIG. 1 , the controller  66  is in signal communication (e.g., hardwired or wirelessly connected) with the sensor system  64  and, more particularly, each of the sensors  68 ,  70  and  72 . The controller  66  is also in signal communication with one or more actuators that control operation of the motor  32 . 
     The controller  66  may be implemented using a combination of hardware and software. The hardware may include memory  74  and a processing device  76 , which includes one or more single-core and/or multi-core processors. The hardware, of course, may also or alternatively include analog and/or digital circuitry other than that described above. 
     The memory  74  is configured to store software (e.g., program instructions) for execution of one or more methods, such as that described below, by the controller  66  and the processing device  76 . The memory  74  may be a non-transitory computer readable medium. The memory  74  may include a volatile memory and/or a nonvolatile memory. Examples of a volatile memory may include a random access memory (RAM) such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a synchronous dynamic random access memory (SDRAM), a video random access memory (VRAM), etc. Examples of a nonvolatile memory may include a read only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a computer hard drive, etc. 
       FIG. 5  is a flow diagram of a method for selectively powering the load  22  with the power system  20  of  FIG. 1 . This method is described below with reference to the transmission  34  and the control system  36  of  FIGS. 1-4  for illustrative purposes. The present method, however, may also be performed using a transmission and/or a control system with configurations other than those described above. The transmission  34 , for example, may have configurations as illustrated in  FIGS. 6-8 . One or more of the sensors  68 ,  70  and  72  of the control system  36  may be respectively arranged with the shafts  38  and/or  24 , or various components of the motor  32  and/or the load  22 . The controller  66  may determine the speeds of and/or torques applied to the transmission components from other related sensor data and/or data stored in the memory  74 . The present method therefore is not limited to any particular power system or load types or configurations. 
     In step  500 , the transmission  34  is configured in first gear (see  FIG. 3 ) and transfers mechanical energy (e.g., torque) from the motor  32  to the load  22 . The motor  32 , for example, rotates to the shaft  38 , which rotates the input shaft  48  and the gear  40 . The gear  40  rotates the gear  41 , which rotates the lay shaft  50  and the gears  42  and  43 . The gear  42  rotates the gear  44 , which rotates the gear  46  and the output shaft  52 . The output shaft  52  rotates the shaft  24 , which rotates the drive wheels  26  (see  FIG. 1 ). 
     In step  502 , the controller  66  receives a shift signal. This shift signal indicates the transmission  34  is to shift out of first gear (see  FIG. 3 ) and into neutral (see  FIG. 2 ). The shift signal may be generated based on an input from a human operator (e.g., a driver); e.g., shifting gears using a paddle shifter. Alternatively, the shift signal may be generated based on the operating state of the motor  32 ; e.g., when the motor  32  is rotating at or above a threshold. 
     In step  504 , the controller  66  receives the torque data from the sensor system  64 . As set forth above, the torque data may be indicative of the torques to which the input shaft  48  and, thus, the gear  44  and  46  are being subjected. 
     In step  506 , the controller  66  signals the motor  32  to operate in a fashion that substantially unloads the meshed gears  44  and  46 . The controller  66 , for example, may operate in a feedback loop with the torque sensor  72  and the motor  32  to drive the torque being applied on the gears  44  and  46  to zero. More particularly, the controller  66  may signal the motor  32  to reduce its power output such that a tangential force between the meshing teeth  56  and  58  of the gears  44  and  46  is substantially zero. 
     In step  508 , the controller  66  signals an actuator to slide the unloaded gear  46  from the first gear position (see  FIG. 3 ) to the neutral position (see  FIG. 2 ) using the shift linkage  62 . In this manner, the actuator disengages the meshed and unloaded gears  44  and  46  from one another such that the transmission  34  no longer transfers mechanical energy from the motor  32  to the load  22 . Of course, in other embodiments, a human operator may manually move the shift linkage  62  to change the position of the gear  46 . 
     In step  510 , the controller  66  receives speed data from the sensor system  64 . This speed data may include the input speed data generated by the input speed sensor  68  and/or the output speed data generated by the output speed sensor  70 . As set forth above, the input speed data may be indicative of the rotational and/or tangential speeds of the input shaft  48  and, thus, the gear  45 . The output speed data may be indicative of the rotational and/or tangential speeds of the output shaft  52  and, thus, the gear  46 . 
     In step  512 , the controller  66  signals the motor  32  to operate in a fashion that synchronizes rotation of the gear  45  with rotation of the gear  46 . The controller  66 , for example, may operate in a feedback loop with the sensors  68  and  70  and the motor  32  to drive the rotational speed of the gear  45  to substantially match the rotational speed of the gear  46 . Alternatively, referring to  FIGS. 7 and 8 , the controller  66  may operate the motor  32  to drive the tangential speed of the gear  42 ,  43  to substantially match the tangential speed of the gear  44 ,  45 , respectively. 
     Referring again to  FIGS. 1-5 , in step  514 , the controller  66  signals the actuator to slide the gear  46  from the neutral position (see  FIG. 2 ) to the second gear position (see  FIG. 4 ) using the shift linkage  62 . In this manner, the actuator engages the synchronized gears  45  and  46  with one another such that the transmission  34  may resume the transfer of mechanical energy from the motor  32  to the load  22 . Of course, in other embodiments, a human operator may manually move the shift linkage  62  to change the position of the gear  46 . 
     Using the method of  FIG. 5 , the transmission  34  may relatively smoothly and/or quickly shift from first gear to neutral to second gear (or between other gears) without, for example, using a clutch or a torque converter to prevent or reduce damage to the gears  40 - 46 ; e.g., “grinding gears”. For example, by disengaging the gears  44  and  46  from one another while unloaded, the risk of damaging the teeth  56  and  58  may be reduced. Similarly, by engaging the gears  45  and  46  with one another while synchronized, the risk of damaging the teeth  56  and  60  may further be reduced. This enables the power system  20  to be configured without a clutch or a torque converter, which may in turn reduce complexity, cost, weight and/or size of the power system  20 . Of course, in other embodiments, the power system  20  may also be configured with a clutch and/or a torque converter. 
       FIG. 6  illustrates another exemplary embodiment of the transmission  34 . In contrast to the transmission  34  of  FIGS. 2-4 , the transmission  34  of  FIG. 6  further includes a plurality of additional gears  78  and  80 . Each of these gears  78  and  80  may be configured as a spur gear or a helical gear as described above. The gear  78  is mounted on as well as rotatably and axially fixed to the lay shaft  50 . The gear  80  is rotatably mounted on and axially fixed to the output shaft  52 . One or more teeth of the gear  78  are meshed with one or more teeth of the gear  80 . These gears  78  and  80  are respectively sized different than the gears  42 - 45  and thereby may provide the transmission  34  with another speed; e.g., a third speed. 
     In addition to the foregoing, the gear  46  of  FIGS. 2-4  may be replaced with one or more rotors  82  and  84 ; e.g., clutch plates. Each of these rotors  82  and  84  may be configured as a collar that slides along and is rotatably fixed to the output shaft  52 . The rotor  82  may slide in a first direction to (e.g., frictionally) engage with the gear  44  and rotatable fix the gear  44  to the output shaft  52 . The rotor  82  may also slide in a second direction to (e.g., frictionally) engage with the gear  45  and rotatable fix the gear  45  to the output shaft  52 . The rotor  84  may slide in the second direction to (e.g., frictionally) engage with the gear  80  and rotatable fix the gear  80  to the output shaft  52 . 
       FIGS. 7 and 8  illustrate still another exemplary embodiment of the transmission  34 . In contrast to the transmission  34  of  FIGS. 2-4 , the transmission  34  of  FIGS. 7 and 8  is configured without the gear  46  and the rotors  82 ,  84  of  FIG. 6 . Each of the gears  44  and  45  is further rotatably fixed to the output shaft  52 . In addition, the output shaft  52  is adapted to slide along its axis between the position of  FIG. 7  and the position of  FIG. 8 . In this manner, a shift linkage  86  may slide the output shaft  52  to engage the gear  44  with the gear  42 , or the gear  45  with the gear  43 . 
     It is to be understood that the terminology used herein is used for the purpose of describing specific embodiments, and is not intended to limit the scope of the present invention. It should be noted that as used herein, the singular forms of “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. In addition, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. 
     Although the description above contains many specific examples, these should not be construed as limiting the scope of the embodiments of the present disclosure, but as merely providing illustrations of some of the presently preferred embodiments of the present invention. It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is to be understood therefore that this disclosure is not limited to the specific embodiments disclosed herein, but it is intended to cover modifications within the spirit and scope of the embodiments of the present disclosure. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.