Control apparatus for power transmission system

#The disclosure of Japanese Patent Application No. 2015-157742 filed on Aug. 7, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

#1. Technical Field

#The present disclosure relates to a control apparatus for a power transmission system including an automatic transmission that is able to provide different power transmission paths that transmit power of a driving force source to a drive wheel.

#Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

#FIG. 1 is a view that illustrates the schematic configuration of a vehicle to which a first embodiment of the present disclosure is applied;

#FIG. 2 is a chart for illustrating changes in drive mode of a power transmission system shown in FIG. 1;

#Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

#FIG. 1 is a view that illustrates the schematic configuration of a vehicle 10 to which a first embodiment of the present disclosure is applied. In FIG. 1, the vehicle 10 includes an engine 12, drive wheels 14, and a power transmission system 16. The engine 12 is a gasoline engine, a diesel engine, or the like, that functions as a driving force source for propelling the vehicle 10. The power transmission system 16 is provided in a power transmission path between the engine 12 and the drive wheels 14. The power transmission system 16 includes a torque converter 20, an input shaft 22, an automatic transmission 24, an output shaft 26, a counter shaft 28, a reduction gear unit 30, a differential gear set 34, a pair of axles 36, and the like. The input shaft 22 is coupled to the torque converter 20. The automatic transmission 24 is coupled to the input shaft 22. The output shaft 26 is coupled to the output side of the automatic transmission 24. The pair of axles 36 are coupled to the differential gear set 34. The torque converter 20 is known as a fluid transmission device coupled to the engine 12 inside a housing 18 that serves as a non-rotating member. The reduction gear unit 30 includes a pair of meshing gears. The pair of meshing gears are respectively provided on the output shaft 26 and the counter shaft 28 so as to be relatively non-rotatable. The differential gear set 34 is coupled to a gear 32. The gear 32 is provided on the counter shaft 28 so as to be relatively non-rotatable. In the thus configured power transmission system 16, the power (when not specifically distinguished from one another, power is synonymous with torque and force) of the engine 12 is transmitted to the pair of drive wheels 14 sequentially via the torque converter 20, the automatic transmission 24, the reduction gear unit 30, the differential gear set 34, the axles 36, and the like.

#The torque converter 20 is interposed in a power transmission path between the engine 12 and the input shaft 22. The torque converter 20 is provided around the input shaft 22 coaxial with the input shaft 22. The torque converter 20 includes a pump impeller 20p and a turbine runner 20t. The pump impeller 20p is coupled to the engine 12. The turbine runner 20t is coupled to the input shaft 22. The torque converter 20 transmits the power of the engine 12 to the input shaft 22. The torque converter 20 includes a known lockup clutch 38. The lockup clutch 38 is able to directly couple the pump impeller 20p and the turbine runner 201 to each other, that is, the input and output rotating members of the torque converter 20 to each other. The power transmission system 16 includes a mechanical oil pump 40 coupled to the pump impeller 20p. The oil pump 40 generates (discharges) hydraulic pressure for shift control over the automatic transmission 24 or supplying lubricating oil to portions of the power transmission system 16 by being driven by the engine 12 to rotate,