Power transmission system for hybrid vehicle

Abstract

A power transmission system for a hybrid vehicle including an engine, a first planetary gearset and a second planetary gear set is provided. In particular, the first planetary gearset includes a plurality of first rotational elements, one of which is coupled with an output shaft of the engine and one of which is coupled with a first motor generator, and two of which are allowed to be directly selectively connected directly by a clutch. The second planetary gearset includes a plurality of second rotational elements, one of which is permanently coupled with one of the first rotational elements of the first planetary gearset, one of which is coupled with a second motor generator and one of which is connected directly with drive unit.

What is claimed is: 
     
         1 . A power transmission system for a hybrid vehicle comprising:
 an engine;   a first planetary gearset including a plurality of first rotational elements, one of which is coupled with an output shaft of the engine, one of which is coupled to a first motor generator, and two of which are directly coupled by a clutch; and   a second planetary gearset including a plurality of second rotational elements, one of which is permanently coupled with one of the first rotational elements of the first planetary gearset, one of which is coupled with a second motor generator and one of which is connected to a drive unit.   
     
     
         2 . The power transmission system according to  claim 1 , wherein the first planetary gearset includes a first sun gear, a first ring gear, and a first canier, and the second planetary gearset includes a second sun gear, a second canier, and a second ring gear. 
     
     
         3 . The power transmission system according to  claim 2 , wherein the first sun gear of the first planetary gearset is coupled with the first motor generator. 
     
     
         4 . The power transmission system according to  claim 2 , wherein the first carrier of the first planetary gearset is coupled with the output shaft of the engine. 
     
     
         5 . The power transmission system according to  claim 2 , wherein the first carrier and the first ring gear of the first planetary gearset are connected by the clutch, and are couplable by the clutch. 
     
     
         6 . The power transmission system according to  claim 2 , wherein the first ring gear of the first planetary gearset is permanently coupled with the second canier of the second planetary gearset. 
     
     
         7 . The power transmission system according to  claim 2 , wherein the first ring gear of the first planetary gearset is permanently coupled with the second ring gear of the second planetary gearset. 
     
     
         8 . The power transmission system according to  claim 2 , wherein the first ring gear of the first planetary gearset is permanently coupled with the second carrier of the second planetary gear set, and the second carrier of the second planetary gearset is connected to the drive unit. 
     
     
         9 . The power transmission system according to  claim 2 , wherein the first ring gear of the first planetary gearset is permanently coupled with the second ring gear of the second planetary gear set, and the second ring gear of the second planetary gearset is connected to the drive unit. 
     
     
         10 . The power transmission system according to  claim 2 , wherein the second sun gear of the second planetary gearset is coupled with the second motor generator. 
     
     
         11 . The power transmission system according to  claim 2 , wherein the second canier of the second planetary gearset is connected to the drive unit. 
     
     
         12 . The power transmission system according to  claim 2 , wherein the second canier of the second planetary gearset is connected and fixed to a brake. 
     
     
         13 . The power transmission system according to  claim 2 , wherein the second ring gear of the second planetary gearset is connected to the drive unit. 
     
     
         14 . The power transmission system according to  claim 2 , wherein the second ring gear of the second planetary gearset is connected and fixed to a brake. 
     
     
         15 . The power transmission system according to  claim 1 , wherein the clutch of the first planetary gearset is coupled during high-speed driving at a high-speed gear position so as to allow the vehicle to run at an invariable gear position. 
     
     
         16 . A power transmission system for a hybrid vehicle comprising:
 an engine;   a first planetary gearset including a first sun gear, a first carrier, and a first ring gear, of which the first sun gear is connected to a first motor generator, of which the first carrier is coupled with an output shaft of the engine, and of which the first ring gear and the first carrier are selectively connected by a clutch wherein when the clutch is engaged, the vehicle operates using a variable gear position as an invariable gear position; and   a second planetary gearset including a second sun gear, a second carrier, and a second ring gear, of which the second sun gear is connected to a second motor generator, of which the second carrier is connected to a drive unit and is permanently coupled with the first ring gear of the first planetary gearset, and of which the second ring gear is fixedly connected to a brake.   
     
     
         17 . A power transmission system for a hybrid vehicle comprising:
 an engine of the hybrid vehicle;   a first planetary gearset made up of a first sun gear, a first carrier, and a first ring gear, of which the first sun gear is connected to a first motor generator, of which the first carrier is coupled with an output shaft of the engine, and of which the first ring gear and the first carrier are connected by a clutch wherein when the clutch is engaged, the vehicle operates using a variable gear position as an invariable gear position during high-speed low-load driving; and   a second planetary gearset made up of a second sun gear, a second carrier, and a second ring gear, of which the second sun gear is connected to a second motor generator, of which the second carrier is fixedly connected to a brake, and of which the second ring gear is coupled with a drive unit and is permanently coupled with the first ring gear of the first planetary gear set.