Patent Publication Number: US-2013237359-A1

Title: Driving apparatus for hybrid vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Japanese Patent Application No. 2012-048913 filed Mar. 6, 2012, the content of which is incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a driving apparatus for a hybrid vehicle and, more particularly, relates to a driving apparatus for a hybrid vehicle, in which the revolution of an oil pump can be changed freely without changing the revolution of an output member. 
     2. Description of Related Art 
     In recent years, as a vehicle, there has been available a hybrid vehicle provided with a motor generator other than an engine as a driving source in addition to the engine. 
     In the driving apparatus of this hybrid vehicle, the power generated from the engine and the motor generator is transmitted to driving wheels via a power transmission mechanism. 
     The power train of a vehicle disclosed in Japanese Patent Application Publication No. JP 2011-37329 includes a power transmission mechanism consisting of an engine, first and second motor generators, and a planetary gear mechanism, and is configured so that the planetary gear mechanism includes three rotating elements consisting of a sun gear, a carrier, and a ring gear, the first motor generator is connected to the sun gear, the engine is connected to the carrier, and an output member for transmitting power to driving wheels and the second motor generator are connected to the ring gear. 
     A clutch is arranged between the first motor generator and the sun gear, and on the other hand, an oil pump is connected to the first motor generator via a one-way clutch. Thereby, the oil pump is driven by the first motor generator, and the reverse rotation of oil pump is prevented by the one-way clutch. 
     In the configuration described in JP 2011-37329, the revolution of the first motor generator changes according to the change in revolution of the second motor generator. However, since the second motor generator is connected to the output member, when the revolution of the second motor generator changes, the running speed of the hybrid vehicle also changes. 
     Therefore, even in the case in which a portion to be lubricated can be lubricated by oil scooped up in the driving apparatus or the like means, the revolution of the oil pump cannot be reduced or stopped, so that there arises a problem that the drive loss of the oil pump increases. 
     Accordingly, an object of the present invention is to provide a driving apparatus for a hybrid vehicle for driving an oil pump by a motor generator, which has a configuration such that the revolution of the oil pump can be changed regardless of the running speed of vehicle, whereby the drive loss of oil pump is reduced. 
     SUMMARY OF THE INVENTION 
     The present invention provides a driving apparatus for a hybrid vehicle connected to an engine as a driving source, comprising two motor generators, a power transmission mechanism, an output member for transmitting power to driving wheels, and an oil pump, the power transmission mechanism including a first planetary gear mechanism and a second planetary gear mechanism each provided with a sun gear, a pinion gear (planetary gear), a ring gear, and a carrier (planetary carrier) for supporting the pinion gear; wherein any two of the sun gear, ring gear, and carrier of the first planetary gear mechanism and any two of the sun gear, ring gear, and carrier of the second planetary gear mechanism are connected individually to each other, so as to form four rotating elements rotating differentially from each other and being arranged along a straight line on a collinear diagram; the output shaft of the engine is connected, via a one-way clutch, to one of the two rotating elements arranged in the middle of the collinear diagram; the output member is connected to the other of the two rotating elements; and the motor generators are connected to the two rotating elements arranged at both ends of the collinear diagram, the oil pump is connected to either one of the two motor generators. 
     The present invention concerns a configuration in which the revolution of the oil pump can be changed regardless of the running speed of vehicle, whereby the drive loss of oil pump can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a skeleton diagram of a driving apparatus for a hybrid vehicle in which an oil pump is connected to a first motor generator; 
         FIG. 2  is a collinear diagram showing the case in which an oil pump is connected to a first motor generator, and the oil pump is not driven (non-operative); 
         FIG. 3  is a collinear diagram showing the case in which an oil pump is connected to a first motor generator, and the oil pump is driven; 
         FIG. 4  is a skeleton diagram of a driving apparatus for a hybrid vehicle in which an oil pump is connected to a second motor generator; 
         FIG. 5  is a collinear diagram showing the case in which an oil pump is connected to a second motor generator, and the oil pump is not driven (non-operative); and 
         FIG. 6  is a collinear diagram showing the case in which an oil pump is connected to a second motor generator, and the oil pump is driven. 
     
    
    
     DETAILED DESCRIPTION 
     In the present invention, an object such that the configuration is made such that the revolution of an oil pump can be changed regardless of the running speed of vehicle, whereby the drive loss of the oil pump is reduced, which is achieved by connecting the oil pump to either one of two motor generators. 
       FIGS. 1 to 6  show embodiments of the present invention. 
     In  FIGS. 1 and 4 , reference sign  1  denotes an engine that is mounted on a hybrid vehicle to serve as a driving source for delivering torque, and  2  denotes a driving apparatus connected to the engine  1 . The engine  1  has an output shaft  3 . 
     The driving apparatus  2  includes an input shaft  4  connected to the output shaft  3  of the engine  1 , two motor generators of a first motor generator (mainly for power generation) (described as “MG 1 ” in the figures)  5  and a second motor generator (mainly for driving) (described as “MG 2 ” in the figures)  6 , a power transmission mechanism  7 , and an output member (described as “OUT” in the figures)  8  for transmitting the power to right and left driving wheels. The revolution of this output member  8  determines the running speed of the hybrid vehicle. 
     The power transmission mechanism  7  is a so-called combined planetary gear mechanism that is combinedly configured by a first planetary gear mechanism (PG 1 )  9  and a second planetary gear mechanism (PG 2 )  10 . 
     The first planetary gear mechanism  9  includes a first sun gear  12  connected to the first motor generator  5  via a first input-side connecting shaft  11 , a first pinion gear  13  meshing with this first sun gear  12 , a first carrier  14  that supports this first pinion gear  13  and is connected to the input shaft  4 , and a first ring gear  15  that meshes with the first pinion gear  13  and is connected to the output member  8 . 
     The second planetary gear mechanism  10  includes a second sun gear  16  connected to the input shaft  4 , a second pinion gear  17  meshing with this second sun gear  16 , a second carrier  18  that supports this second pinion gear  17  and is connected to the first ring gear  15 , and a second ring gear  19  meshing with the second pinion gear  17 . This second ring gear  19  connects with the second motor generator  6  via a second input-side connecting shaft  20 . 
     The first planetary gear mechanism  9  and the second planetary gear mechanism  10  have a configuration such that two of the first sun gear  12 , the first ring gear  15 , and the first carrier  14  constituting the first planetary gear mechanism  9  and two of the second sun gear  16 , the second ring gear  19 , and the second carrier  18  constituting the second planetary gear mechanism  10  are connected individually to each other, and four rotating elements T 1  to T 4  rotating differentially each other are formed as shown in  FIG. 2 . 
     Specifically, in the first planetary gear mechanism  9  and the second planetary gear mechanism  10 , the first carrier  14  and the second sun gear  16  are connected to each other via the input shaft  4 , and the second carrier  18  and the first ring gear  15  are connected to each other. In such a configuration, the sun gear  12  forms the first rotating element TI, the first carrier  14  and the second sun gear  16  are connected integrally and forms the second rotating element T 2 , the first ring gear  15  and the second carrier  18  are connected integrally and forms the third rotating element T 3 , and the second ring gear  19  forms the fourth rotating element T 4 . 
     In this driving apparatus  2 , in the case in which the four rotating elements T 1  to T 4  are arranged in a collinear diagram as shown in  FIG. 2 , the rotating elements T 1  to T 4  are arranged on a straight line, the output shaft  3  of the engine  1  is connected to the rotating element T 2 , which is one of the two rotating elements T 2  and T 3  arranged in the center of the collinear diagram, via a one-way clutch  21 , and the output member  8  is connected to the rotating element T 3 , which is the other of the two rotating elements T 2  and T 3 . The one-way clutch  21  is arranged between a housing of the driving apparatus  2  and the input shaft  4  to prevent the input shaft  4  from rotating in the direction reverse to the direction of rotation of the output shaft  3  of the engine  1 . 
     Specifically, as described above, the first carrier  14  and the second sun gear  16 , which serve as the second rotating element T 2 , are connected to the output shaft  3  of the engine  1  via the input shaft  4 , and the first ring gear  15  and the second carrier  18 , which serve as the third rotating element T 3 , are connected to the output member  8 . Also, in the power transmission mechanism  7 , to the two rotating elements arranged at both ends on the collinear diagram, the respective motor generators are connected. 
     Specifically, as described above, the first motor generator  5  is connected to the first sun gear  12 , which serves as the first rotating element T 1 , via the first input-side connecting shaft  11 . The second motor generator  6  is connected to the second ring gear  19 , which serves as the fourth rotating element T 4 , via the second input-side connecting shaft  20 . 
     To either one of the first motor generator  5  and the second motor generator  6 , for example, as shown in  FIG. 1 , to the first motor generator  5 , an oil pump (described as “O/P” in the figures)  22  is connected via the first input-side connecting shaft  11 . This oil pump  22  supplies a lubricating oil to portions requiring lubrication in the driving apparatus  2 . 
     As shown in  FIG. 4 , the oil pump  22  can be connected, via the second input-side connecting shaft  20 , to the second motor generator  6  as either one of the first motor generator  5  and the second motor generator  6 . 
     Therefore, the revolution of the oil pump  22  is changed by the driving state of the first motor generator  5  or the second motor generator  6  regardless of the running speed of the hybrid vehicle corresponding to the revolution of the output member  8 . 
     That is, in this embodiment, without changing the revolution of the third rotating element T 3  to which the output member  8  is connected, the revolutions of the other three rotating elements (the first rotating element T 1 , the second rotating element T 2 , and the fourth rotating element T 3 ) can be changed. 
     In the above-described configuration, in the case in which the hybrid vehicle is run by using the engine  1 , the first motor generator  5 , and the second motor generator  6  in combination, the hybrid vehicle can be run in the state in which the rotation of either one of the first motor generator  5  and the second motor generator  6  is stopped, and the power consumption of the motor generator whose rotation has been stopped is made zero. 
     At this time, if the first motor generator  5  (or the second motor generator  6 ) to which the oil pump  22  is connected is stopped, the hybrid vehicle becomes ready to run without being affected by the drive loss of the oil pump  22 . 
     When it becomes necessary to supply a lubricating oil from the oil pump  22 , the revolution of the first motor generator  5  (or the second motor generator  6 ) to which the oil pump  22  is connected has only to be increased. 
     Therefore, the driving apparatus  2  is configured so that, during the running of the hybrid vehicle, the revolutions of the engine  1  and the first motor generator  5  (or the second motor generator  6 ) are controlled so that the oil pump  22  and either one of the motor generators  5  and  6  to which the oil pump  22  is connected are stopped without changing the revolution of the output member  8 . 
     Next, in the driving apparatus  2  shown in  FIG. 1 , in which the oil pump  22  is connected to the first motor generator  5 , the operating state of the oil pump  22  is explained with reference to  FIGS. 2 and 3 . 
       FIG. 2  shows the case in which the oil pump  22  is connected to the first motor generator  5 , and the hybrid vehicle is run by the driving forces of the engine  1  and the second motor generator  6 . In this case, the hybrid vehicle is in a state in which the oil pump  22  need not be driven, and the revolutions of the engine  1  and the second motor generator  6  are regulated so that the rotation of the first motor generator  5  is stopped. The revolution of the output member  8  at this time can be maintained a predetermined value F 1 . 
     On the other hand, in the case in which the oil pump  22  needs to be driven, as shown in  FIG. 3 , if the revolutions of the engine  1  and the second motor generator  6  are increased, the revolution of the first motor generator  5  is increased to P 1  while the revolution of the output member  8  is maintained at the predetermined value F 1 , and the oil pump  22  can be driven. 
     Also, in the driving apparatus  2  shown in  FIG. 4 , in which the oil pump  22  is connected to the second motor generator  6 , the operating state of the oil pump  22  is explained with reference to  FIGS. 5 and 6 . 
       FIG. 5  shows the case in which the oil pump  22  is connected to the second motor generator  6 , and the hybrid vehicle is run by the driving forces of the engine  1  and the first motor generator  5 . In this case, the hybrid vehicle is in a state in which the oil pump  22  need not be driven, and the revolutions of the engine  1  and the first motor generator  5  are regulated so that the rotation of the second motor generator  6  is stopped. The revolution of the output member  8  at this time can be kept at a predetermined value F 2 . 
     On the other hand, in the case in which the oil pump  22  needs to be driven, as shown in  FIG. 6 , if the first motor generator  5  is rotated in the reverse direction, when the rotation of the second motor generator  6  is increased to revolution P 2  while the revolution of the output member  8  is maintained at the predetermined value F 2 , the oil pump  22  is operated to perform lubrication. 
     The above is an explanation of the embodiment of the present invention. Hereunder, the configuration of the above-described embodiment is explained so as to correspond to the claims. 
     First, in the invention in accordance with claim  1 , in the driving apparatus  2  configured so that the motor generators  5  and  6  are connected to the two rotating elements T 1  and T 4  arranged at both ends of the collinear diagram, respectively, the oil pump  22  is connected to either one of the motor generators  5  and  6 . 
     Thereby, in the case in which the engine  1 , one of the motor generators  5  and  6 , and the output member  8  are connected, in the above-described relation, to the power transmission mechanism  7  configured so that the four rotating elements T 1  to T 4  rotating differentially from each other are arranged on a straight line on the collinear diagram, by changing the revolutions of one of the motor generators  5  and  6  and the engine  1 , the revolution of the other of the motor generators can be changed freely without changing the revolution of the output member  8 . 
     Also, considering the above-described state, the oil pump  22  is connected to either one of the motor generators  5  and  6 , so that the revolution of the oil pump  22  can be changed freely without changing the revolution of the output member  8 . Therefore, the power transmission mechanism  7  can be lubricated by the oil splashed up by the power transmission mechanism  7 , and in the case in which the oil pump  22  need not be driven, the revolutions of the motor generator  5  or  6  and the engine  1  are changed to reduce or stop the revolution of the oil pump  22 , whereby the drive loss of the oil pump  22  is reduced, and the consumption of fuel and electric power can be reduced. 
     Furthermore, according to the above-described configuration, the oil pump  22  can be stopped without using a clutch or the like, so that the construction of the driving apparatus  2  can be simplified. 
     Also, in the invention in accordance with claim  2 , during the running of the hybrid vehicle, the revolutions of the engine  1  and the motor generator  5  or  6  are controlled so that the oil pump  22  and the motor generator  5  or  6  to which the oil pump  22  is connected are stopped without changing the revolution of the output member  8 . 
     Thereby, during the running of the hybrid vehicle, the oil pump  22  and the motor generator  5  or  6  to which the oil pump  22  is connected are stopped without changing the revolution of the output member  8 , and the drive loss created by the driving of these devices can be reduced. 
     The driving apparatus in accordance with the present invention can be applied to not only a hybrid vehicle but also any other motor-driven vehicle such as an electric vehicle.