Abstract:
A hybrid-type power transmission in which an internal combustion engine and an electric rotating machine are used as a source of power for driving an output shaft through a change-speed mechanism. In the hybrid power transmission, the operation of the electric rotating machine is controlled in such a manner that the rotation speed of a rotor-side rotary member is synchronized with the rotation speed of an input-side or output-side rotary member when the rotation speed of the rotor-side rotary member becomes higher in a predetermined difference than the rotation speed of the input-side or output-side rotary member in shifting operation of a sleeve coupled with the rotor-side rotary member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hybrid-type power transmission in which an internal combustion engine and an electric rotating machine are used as a source of power for driving an output shaft through a change-speed mechanism. 
     2. Technical Background of the Invention 
     In the PCT application (PCT/JP2008/068678) filed on Oct. 15, 2008, one of the inventors has proposed a hybrid-type power transmission of this kind. As shown in  FIGS. 1 and 2 , the hybrid-type power transmission comprises an input shaft  10  for drive connection with an internal combustion engine  14 , a change-speed mechanism  30  having a plurality of change-speed gear trains to be selectively established for transmitting a drive power from the input shaft  10  to an output shaft  11  at a selected speed ratio, a changeover mechanism  20  including a rotor-side rotary member  21  mounted on the input shaft for rotation with a rotor  13   a  of an electric rotating machine  13 , an output-side rotary member  25  mounted on the input shaft  10  for rotation with a drive gear  16  in drive connection with the output shaft  11 , an input-side rotary member  24  mounted on the input shaft  10  for rotation therewith between the rotor-side rotary member  21  and the output-side rotary member  25 , and a sleeve  26  coupled with the rotor-side rotary member  21  for rotation therewith and shiftable in an axial direction to be selectively engaged with the output-side rotary member  25  or the input-side rotary member  24 , and a control device  18  for controlling each operation of the electric rotating machine  13 , the changeover mechanism  20  and the change-speed mechanism  30 . The electric rotating machine  13  is in the form of a motor-generator activated under control of the control device  18  to drive the input shaft  10  or the output shaft  11  or to be driven by the input shaft  10  or the output shaft  11 . 
     As shown in  FIG. 1 , the change-speed mechanism  30  includes the plurality of change-speed gear trains G 1 ˜G 5  and a backward gear train GB arranged in parallel between the input and output shafts  10  and  11 , and a plurality of clutches C 1 ˜C 3  for changing over the gear trains G 1 ˜G 5 . The control device  18  is provided to selectively effect engagement of the clutches C 1 ˜C 3  through a shift actuator  19  and shift-forks F 1 ˜F 3  in response to instruction from a driver thereby to selectively establish a drive power train from the change-speed gear trains G 1 ˜G 5  and backward gear train GB for transmission of drive power between the input shaft  10  and the output shaft  11 . In a condition where a change-speed gear train was selected, the output shaft  11  is driven by the internal combustion engine  14  and/or the electric rotating machine  13  to drive left and right road wheels (not shown) through an output drive gear  31 , an output driven gear  32 , a differential  33  and drive shafts  34   a ,  34   b.    
     As shown in  FIGS. 1 and 2 , the changeover mechanism  20  for selectively effecting drive connection of the electric rotating machine  13  with the input shaft  10  or the output shaft  11  includes the rotor-side rotary member  21  coupled with the rotor  13   a  of electric rotating machine  13  for rotation therewith, the input-side rotary member  24  mounted on the input shaft  10  for rotation therewith, the output-side rotary member  25  coupled with the drive gear  16  in drive connection with the output shaft  11  for rotation therewith, and the cylindrical sleeve  26  coupled with the rotor-side rotary member  21  for rotation therewith and shiftable in an axial direction to be engaged with the input-side rotary member  24  or the output-side rotary member  25  for transmission of the drive power. 
     As shown in detail in  FIG. 2 , the input-side rotary member  24  is coaxially mounted at its hub portion on the input shaft  10  by means of spline connection and fixed in place by means of fastening rings. At opposite sides of the input-side rotary member  24 , the rotor  13   a  of the electric rotating machine  13  and the drive gear  16  are rotatably supported at their hub portions on the input shaft  10  through a needle roller bearing, respectively. The drive gear  16  is in drive connection with the output shaft  11  through a driven gear  17 . The rotor-side rotary member  21  and output-side rotary member  25  are coaxially coupled at their hub portions with the rotor  13   a  and drive gear  16  for rotation therewith respectively by means of serration press-fit. The rotary members  21 ,  24 ,  25  are formed with outer splines  21   a ,  24   a ,  25   a  of the same cross-section, respectively. The input-side rotary member  24  is spaced from the output-side rotary member  25  in a distance. The cylindrical sleeve  26  is formed with axially spaced inner splines  26   a  and  26   b . The first inner spline  26   a  is slidably engaged with the outer spline  21   a  of rotor-side rotary member  21 , while the second inner spline  26   b  is selectively engaged with the outer spline  24   a  of input-side rotary member  24  or the outer spline  25   a  of output-side rotary member  25  in response to axial movement of the sleeve  26 . 
     A shift-fork  27  is engaged with an annular groove  26   c  formed on the outer periphery of sleeve  26  to be operated by activation of the shift actuator  19  through a shift-rod  28  (see  FIG. 1 ). When the sleeve  26  is placed at a center of its axial movement, the inner spline  26   b  of sleeve  26  is positioned between the input-side rotary member  24  and output-side rotary member  25 . When the shift actuator  19  is activated under control of the control device  18  in response to an instruction of a driver, the sleeve  26  is shifted in an axial direction to be selectively engaged to the outer spline  24   a  of input-side rotary member  24  or the outer spline  25   a  of output-side rotary member  25 . 
     For smooth engagement of the splines in shift movement of the sleeve, it is required to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of the input-side rotary member  24  or the output-side rotary member  25 . In the changeover mechanism  20 , the electric rotating machine  13  is operated under control of the control device  18  to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of input-side rotary member  24  or the output-side rotary member  25 . 
     When a friction clutch  15  in the hybrid-type power transmission is engaged during operation of the internal combustion engine  14  in a condition where either one of the gear trains of the change-speed mechanism  30  was selected, the drive road wheels of the vehicle are driven by the engine  14  through the selected gear train. When the speed reduction ratio of the drive gear  16  and driven gear  17  is selected between the speed reduction ratios of the second change-speed gear train G 2  and the third change-speed gear train G 3 , the rotation speed of output-side rotary member  25  changes during lapse of a time as shown by a solid line No in  FIG. 7 . In such an instance, the rotation speed of the input-side rotary member  24  changes in accordance with the change-speed ratio of the selected gear train as shown by solid lines Ni 1 ˜Ni 5 . In the graph of  FIG. 7 , the rotation speed of input-side rotary member  24  is represented by the solid line Ni 1  when the first change-speed gear train  01  is selected and represented by the solid line Ni 2  when the second change-speed gear train G 2  is selected. In a condition where the change-speed gear trains were selected as described above, the changeover mechanism  20  is operated under control of the control device  18  in such a manner that the rotor-side rotary member  21  is brought into engagement with the input-side rotary member  24  or the output-side rotary member  25  in accordance with a depressed amount of an acceleration pedal, the selected change-speed gear train, the rotation speeds of the input and output shafts  10 ,  11 , and acceleration of the vehicle. 
     Illustrated in  FIG. 6  is a condition where the rotor-side rotary member  21  is selectively connected with the output-side rotary member  25  or the input-side rotary member  24  being rotated by the first change-speed gear train G 1  or the second change-speed gear train G 2 . When the rotor-side rotary member  21  is disconnected from the input-side rotary member  24  and connected with the output-side rotary member  25 , the shift actuator  19  is activated under control of the control device  18  to shift the sleeve  26  in such a manner as to disconnect the second inner spline  26   b  of sleeve  26  from the outer spline  24   a  of input-side rotary member  24 . In such an instance, the electric rotating machine  13  is activated under control of the control device  18  to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of output-side rotary member  25 . To effect the synchronization, the rotation speed of the output-side rotary member  25  is defined as a target rotation speed No. Thus, the activation, of electric rotating machine  13  is controlled in such a manner that the rotation speed Nmc of rotor-side rotary member  21  approaches the target rotation speed No at a speed proportional to a difference with the target rotation speed No. With such control of the electric rotating machine  13 , the rotation speed Nine of rotor-side rotary member  21  decreases as shown in  FIG. 6  and approaches to the target rotation speed No. After synchronized with the target rotation speed No, the rotation speed Nmc further decreases due to mechanical resistances in the electric rotating machine during lapse of a time after start of the shift operation of the sleeve  26 . After synchronization of the rotation speed Nmc with the target rotation speed No, the shift actuator  19  is activated again under control of the control device  18  to shift the sleeve  26  in such a manner as to bring the second inner spline  26   b  into engagement with the outer spline  25   a  of output-side rotary member  25  thereby to connect the rotor-side rotary member  21  to the output-side rotary member  25 . 
     Illustrated in  FIG. 3(   a   1 ) are the second inner spline  26   b  of sleeve  26  and the outer spline  25   a  of output-side rotary member  25  to be engaged with each other upon synchronization of the rotation speed Nmc with the target rotation speed No. As shown in the figure, the distal ends of splines  26   b  and  25   a  are spaced in a distance in an axial direction. The lapse of a time after start of the shift operation of sleeve  26  is caused by the distance between the distal ends of splines  28   b  and  25   a  and is affected by the shift speed of sleeve  26  and phase relationship between the splines  26   b  and  25   a . The lapse of the time after synchronization of the rotation speed Nmc with the target rotation speed No will become a minimum value Tm 1  when the chamfer apex  26   b    1  of the second inner spline  26   b  is engaged with the chamfer apex  25   a   1  of outer spline  25   a  and will become a maximum value Tm 2  when the chamfer proximal end  26   b    2  of the second inner spline  26  is engaged with the chamfer proximal end  25   a    2  of the outer spline  25   a . (see imaginary lines b 2  in  FIG. 3(   b   1 )). 
     As described above, the rotation speed Nmc of sleeve  26  in slidable engagement with the rotor-side rotary member  21  is decreased after synchronized with the target rotation speed No as shown by the imaginary line Nmc 1  in  FIG. 6  and is rapidly increased when the sleeve  26  is engaged with the output-side rotary member  25  between the minimum lapse of the time Tm 1  and the maximum lapse of the time Tm 2 . 
     When the rotor-side rotary member  21  is disconnected from the output-side rotary member  25  and connected to the input-side rotary member  24 , the shift actuator  19  is activated under control of the control device  18  to shift the sleeve  26  in such a manner as to disconnect the second inner spline  26   b  from the outer spline  25   a  of output-side rotary member  25 , while the electric rotating machine  13  is activated under control of the control device to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of input-side rotary member  24 . After synchronization of the rotation speeds, the shift actuator  19  is sequentially activated under control of the control device  18  to shift the sleeve  26  in such a manner as to bring the second inner spline  26   b  of sleeve  26  into engagement with the outer spline  24   a  of input-side rotary member  24 . In such an instance, the rotation speed Nmd of sleeve  26  is increased by synchronization with the rotation speed of input-side rotary member  24  and is once decreased after synchronization with the rotation speed of input-side rotary member  24  as shown by an imaginary line Nmd 1  in  FIG. 6 . Subsequently, the rotation speed Nmd 1  of sleeve  26  is rapidly increased to the rotation speed Ni of input-side rotary member  24  when the sleeve  26  is engaged with the input-side rotary member  24  between the minimum lapse of the time Tm 1  and the maximum lapse of the time Tm 2 . 
     As described above, the electric rotating machine is activated under control of the control device to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of input-side rotary member  24  or output-side rotary member  25  in shifting operation of the sleeve  26 . In such an instance, the rotation speed of sleeve  26  is rapidly increased after once decreased when the sleeve is shifted to bring the rotor-side rotary member  21  into engagement with the output-side rotary member  25  or the input-side rotary member  24 . This causes impact noise in shifting operation of the sleeve  26  in the changeover mechanism  20 . 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a control device for the electric rotating machine in the hybrid-type power transmission capable of solving the problem discussed above. 
     According to the present invention, the object is accomplished by providing a hybrid-type power transmission comprising an input shaft for drive connection with an internal combustion engine, a change-speed mechanism having a plurality of change-speed gear trains to be selectively established for transmitting a drive power from the input shaft to an output shaft at a selected speed ratio, and a changeover mechanism for selectively effecting drive connection of an electric rotating machine with the input shaft or the output shaft. The changeover mechanism includes a rotor-side rotary member mounted on the input shaft for rotation with a rotor of the electric rotating machine, an output-side rotary member mounted on the input shaft for rotation with a drive gear in drive connection with the output shaft, an input-side rotary member mounted on the input shaft for rotation therewith between the rotor-side rotary member and the output-side rotary member, and a sleeve coupled with the rotor-side rotary member for rotation therewith and shiftable in an axial direction to be selectively engaged with the output-side rotary member or the input-side rotary member. A control device for the change-speed mechanism and the electric rotating machine is arranged to control the rotation speed of the electric rotating machine in such a manner that the rotation speed of the rotor-side rotary member synchronizes with a target speed higher in a predetermined difference than the rotation speed of the input-side or output-side rotary member in shifting operation of the sleeve. 
     In a practical embodiment of the present invention, the difference of the rotation speeds of the rotor-side rotary member and the input-side or output-side rotary member is determined in such a manner that the rotation speed of the rotor-side rotary member decreases less than that of the input-side or output-side rotary member at a time when the sleeve is brought into engagement with the input-side or output-side rotary member after synchronization of the rotation speed of the rotor-side rotary member with the target speed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         FIG. 1  is a skeleton view illustrating components of a hybrid-type power transmission; 
         FIG. 2  is a partly enlarged sectional view of a changeover mechanism in the hybrid-type power transmission shown in  FIG. 1 , 
         FIGS. 3(   a   1 ),  3 ( b   1 ) each illustrate a section circumferentially taken along  3 - 3  in  FIG. 2 , 
         FIGS. 3(   a   2 ),  3   b   2 ) each illustrate the rotation speed of the rotor-side rotary member after synchronization with the rotation speed of the output-side rotary member, 
         FIGS. 4(   a   1 ),  3 ( b   1 ) each illustrate a modification of each chamfer of the inner and output splines shown in  FIGS. 3(   a   1 ),  3 ( b   1 ), 
         FIGS. 4(   a   2 ),  3   b   2 ) each illustrate the rotation speed of the rotor-side rotary member after synchronization with the rotation speed of the output-side rotary member, 
         FIG. 5  is a graph illustrating transition of the rotation speed of the rotor-side rotary member in shifting operation of the sleeve in the changeover mechanism, 
         FIG. 6  is a graph illustrating transition of the rotation speed of the rotor-side rotary member in shifting operation of the sleeve in the changeover mechanism, and 
         FIG. 7  is a graph illustrating change of the rotation speed of the input-side rotary member in the changeover mechanism. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention adapted to the hybrid-type power transmission described above with reference to  FIGS. 1 and 2  will be described with reference to  FIG. 5 . Assuming that the sleeve  26  of the changeover mechanism  20  is shifted by operation of the shift actuator under control of the control device  18  to connect the rotor-side rotary member  21  to the output-side rotary member  25  in a condition where the rotation speed of input-side rotary member  24  is higher than the rotation-speed of output-side rotary member  25  as shown in  FIG. 5 , the electric rotating machine  13  is activated under control of the control device  18  to synchronize the rotation speed of rotor-side rotary member  21  with the rotation speed of output-side rotary member  25 . In this embodiment, a rotation speed in a difference Δo higher than the rotation speed No of the output-side rotary member  25  is defined as a target rotation speed Ndo for synchronization. Thus, the electric rotating machine  13  is operated under control of the control device  19  in such a manner that the rotation speed Nma of rotor-side rotary member  21  decreases and synchronizes with the target rotation speed Ndo as shown in  FIG. 5 . After synchronized with the target rotation speed Ndo, the rotation speed Nma of rotor-side rotary member  21  further decreases less than the target rotation speed Ndo due to mechanical resistances in the electric rotating machine  13  as shown by an imaginary line Nma 2 . 
     In this embodiment, the difference Δo is determined in such a manner that the imaginary line Nma 2  indicative of the rotation speed of rotor-side rotary member  21  crosses the solid line No indicative of the rotation speed of output-side rotary member  25  at a time between the minimum and maximum lapse of times Tm 1  and Tm 2  during which the apex of inner spline  26   b  of sleeve  26  is brought into engagement with the apex of outer spline  25   a  of output-side rotary member  25 . Practically, the difference Δo is determined on a basis of various factors such as a selected gear train, each rotation speed of the input and output shafts  10 ,  11 , acceleration of the vehicle, a temperature affecting stir-resistance of lubricant, etc. 
     When the inner spline of sleeve  26  is engaged with the outer spline of output-side rotary member  25  at the time between the minimum and maximum lapse of times Tm 1  and Tm 2 , the rotation speed Nma of sleeve  26  is changed over to the rotation speed No of output-side rotary member  25 . In the case that the target rotation speed Ndo is determined as described above, the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  becomes zero in a small extent between the minimum and maximum lapse of times Tm 1  and Tm 2 . 
     When the shift actuator  19  is activated under control of the control device  18  to shift the sleeve in such a manner as to disconnect the rotor-side rotary member  21  from the output-side rotary member  25 , the electric rotating machine  13  is activated under control of the control device  19  to synchronize the rotation speed of rotor-side rotary member  21  with the input-side rotary member  24 . In such an instance, a rotation speed in a difference Δi higher than the rotation speed Ni is defined as a target rotation speed Ndi in the same manner as described above. Thus, the electric rotating machine  13  is activated under control of the control device  18  in such a manner that the rotation speed Nmb of rotor-side rotary member  21  increases and synchronizes with the target rotation speed Ndi as shown in  FIG. 5 . After synchronized with the target rotation speed Ndi, the rotation speed Nmb of rotor-side rotary member  21  decreases less than the target rotation speed Ndi due to mechanical resistance in the electric rotating machine  13  as shown by an imaginary line Nmb 2 . 
     As shown in  FIG. 3(   a   1 ), the inner spline  26   b  of sleeve  26  is formed at its opposite ends with a chamfer of triangle in cross-section to be engaged with a chamfer of triangle in cross-section formed on each distal end of the outer splines  24   a ,  25   a  of input-side and output-side rotary members  24 ,  25 . As the rotation speed Nma of sleeve  26  is higher than the rotation speed No of the output-side rotary member  25  after synchronization with the target rotation speed Ndi as described above, the inner spline  26   b  of sleeve  26  tend to be moved toward the outer spline  25   a  of output-side rotary member  25  in shifting operation of the sleeve  26  as shown by solid arrows in  FIG. 3(   a   1 ). If in such an instance, the chamfer of inner spline  26   b  is brought into engagement at its front side with the back side of the chamfer of outer spline  25   a  in a rotation direction, the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  decreases as shown in  FIG. 3(   a   2 ). When the chamfer of sleeve  26  is moved back in a reverse rotation direction by engagement with the chamfer of output-side rotary member  25 , the difference of the rotation speeds becomes minus. When the proximal end  26   b    2  of the chamfer of inner spline  26   b  displaces over the proximal end  25   a    2  of the chamfer of outer spline  25   a , the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  becomes zero. 
     If as shown in  FIG. 3(   b   1 ), the chamfer of inner spline  26   b  is brought into engagement at its back side with the front side of the chamfer of outer spline  25   a  in a rotation direction, the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  decreases as shown in  FIG. 3(   b   2 ). When the chamfer of sleeve  26  is engaged with the chamfer of outer spline  25   a  as shown by an imaginary line b 1 , the sleeve  26  is moved in the rotation direction to increase the difference of the rotation speeds of sleeve  26  and output-side rotary member  25 . When the proximal end  26   b   2  of the chamfer of inner spline  26   a  displaces over the proximal end  25   a   2  of the chamfer of outer spline  25   a , the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  becomes zero. 
     As the difference between the rotation speeds of rotor-side rotary member  21  and input-side rotary member  24  or output-side rotary member  25  becomes extremely small in shifting operation of the changeover mechanism, the pushback force acting on the sleeve  26  becomes extremely small, and the occurrence of impact noise in shifting operation is extremely reduced. This is effective to bring the sleeve  26  into smooth engagement with the input-side rotary member  24  or output-side rotary member  25 . 
     Illustrated in  FIGS. 4(   a   1 ),  4 ( b   1 ) is a modification of each chamfer of the inner spline  26   b  of sleeve  26  and outer splines  24   a ,  25   a  of rotary members  24 ,  25  in the changeover mechanism. In this modification, each chamfer of the inner spline  26   b  is formed at its backside with an inclined surface  26   b    5 , while each chamfer of the outer splines  24   a ,  25   a  of rotary members  24 ,  25  is formed at its front side with an inclined surface  24   a    5 ,  25   a    5 . When the sleeve  26  is shifted to the output-side rotary member  25 , the inner spline  26   b  of sleeve  26  is displaced toward the outer spline  25   a  of output-side rotary member  25  as shown by solid arrows and brought into engagement with the outer spline  25   a  as shown in  FIG. 4(   a   1 ) or  4 ( b   1 ). 
     When the inner spline  26   b  of sleeve  26  is brought into engagement with the outer spline  25   a  of output-side rotary member  25  as shown in  FIG. 4(   a   1 ), the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  decreases as shown by an imaginary line Nma 2  in  FIG. 4(   a   2 ). When the splines  26   b  and  25   a  are engaged with each other at their side surfaces as shown by an imaginary line c 1 , the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  becomes zero without any increase as shown in  FIG. 4(   a   2 ). When the inner spline  26   b  of sleeve  26  is brought into engagement with the outer spline  25   a  of output-side rotary member  25  as shown in  FIG. 4(   b   1 ), the difference between the rotation speeds of sleeve  26  and output-side rotary member  25  decreases as shown by an imaginary line Nma 2  in  FIG. 4(   b   2 ). When the splines  26   b  and  25   a  are engaged with each other at their chamfers, the sleeve  26  is moved in the rotation direction to increase the difference between the rotation speeds as shown in  FIG. 4(   b   2 ). When the proximal end  26   b   4  of inner spline  26   b  displaces over the proximal end  25   a   4  of outer spline  25   a  as shown by an imaginary line d 2  in  FIG. 4(   b   1 ), the difference between the rotation speeds becomes zero as shown in  FIG. 4(   b   2 ).