Multiple Speed Automatic Transmission

Abstract

A multi-speed automatic transmission includes an input, an output, a first gear unit drivable connected to the input and producing a gear ratio of a speed of the input and a speed of the first gear unit output, a planetary gear unit including a modified Simpson gearset, the gear unit being secured to first, second, third, fourth and fifth rotating members, the fifth member being secured to the output for rotation therewith, a first clutch being operable to connect the first rotating member and the first gear unit output, a second clutch being operable to connect the second rotating member and the first gear unit output, a third clutch being operable to connect the third rotating member and an element rotating at a speed of the input, a fourth clutch being operable to connect the fourth rotating member and said element rotating at the speed of the input, a first brake being operable to hold the fourth rotating member against rotation, and a second brake being operable to hold the third rotating member against rotation.

1 . A multi-speed automatic transmission comprising:
 an input;   an output;   a first gear unit including a carrier drivable connected to the input, a nonrotating pinion that revolves with the carrier and meshes with a first gear unit output, the first gear unit producing a gear ratio of a speed of the input and a speed of the first gear unit output greater than unity;   a planetary gear unit including a modified Simpson gearset, the gear unit being secured to first, second, third, fourth and fifth rotating members, the fifth rotating member being secured to the output for rotation therewith,   a first clutch being operable to connect the first rotating member and the first gear unit output;   a second clutch being operable to connect the second rotating member and the first gear unit output;   a third clutch being operable to connect the third rotating member and an element rotating at a speed of the input;   a fourth clutch being operable to connect the fourth rotating member and said element rotating at the speed of the input;   a first brake being operable to hold the fourth rotating member against rotation; and   a second brake being operable to hold the third rotating member against rotation.   
   
   
       2 . The transmission of  claim 1  wherein:
 the modified Simpson gearset includes a first sun gear secured to the fourth rotating member, a second sun gear secured to the second rotating member, a first ring gear secured to the fifth rotating member and the output, a first carrier secured to the third rotating member, first planet pinions rotatably supported on the first carrier and meshing with the first sun gear, the second sun gear and the first ring gear; and further comprising   a simple planetary gearset includes a third sun gear secured to the second rotating member, a second ring gear secured to the first rotating member, a second carrier secured to the fifth rotating member and the output, and second planet pinions supported on the second carrier and meshing with the third sun gear and the second ring gear.   
   
   
       3 . The transmission of  claim 1  wherein operation in a forward gear or a reverse gear is produced by concurrent engagement of two of the group consisting of the first clutch, the second clutch, the third clutch, the fourth clutch, the first brake, and the second brake. 
   
   
       4 . The transmission of  claim 1  wherein engagement of the first clutch and the second brake and disengagement of the second clutch, the third clutch, the fourth clutch, and the first brake produce a first forward gear having a first gear ratio. 
   
   
       5 . The transmission of  claim 1  wherein engagement of the first clutch and the first brake and disengagement of the second clutch, the third clutch, the fourth clutch, and the second brake produce a second forward gear having a second gear ratio that is less than the first gear ratio. 
   
   
       6 . The transmission of  claim 1  wherein engagement of the first clutch and the second clutch and disengagement of the third clutch, the fourth clutch, the first brake, and the second brake produce a third forward gear having a third gear ratio that is less than the second gear ratio. 
   
   
       7 . The transmission of  claim 1  wherein engagement of the first clutch and the fourth clutch and disengagement of the second clutch, the third clutch, the first brake, and the second brake produce a fourth forward gear having a fourth gear ratio that is less than the third gear ratio. 
   
   
       8 . The transmission of  claim 1  wherein engagement of the first clutch and the third clutch and disengagement of the second clutch, the fourth clutch, the first brake, and the second brake produce a fifth forward gear having a fifth gear ratio that is less than the fourth gear ratio. 
   
   
       9 . The transmission of  claim 1  wherein engagement of the third clutch and the fourth clutch and disengagement of the first clutch, the second clutch, the first brake, and the second brake produce a sixth forward gear having a sixth gear ratio that is less than the fifth gear ratio. 
   
   
       10 . The transmission of  claim 1  wherein engagement of the second clutch and the third clutch and disengagement of the first clutch, the fourth clutch, the first brake, and the second brake produce a seventh forward gear having a seventh gear ratio that is less than the sixth gear ratio. 
   
   
       11 . The transmission of  claim 1  wherein engagement of the first brake and the third clutch and disengagement of the first clutch, the second clutch, the fourth clutch, and the second brake produce an eight forward gear having a eighth gear ratio that is less than the seventh gear ratio. 
   
   
       12 . The transmission of  claim 1  wherein engagement of the second clutch and the second brake and disengagement of the first clutch, the third clutch, the fourth clutch, and the first brake produce a low speed reverse gear having a first reverse gear ratio. 
   
   
       13 . The transmission of  claim 1  wherein engagement of the fourth clutch and the second brake and disengagement of the first clutch, the second clutch, the third clutch, and the first brake produce a relatively higher reverse gear having a gear ratio that is less than the first reverse gear ratio. 
   
   
       14 . A multi-speed automatic transmission comprising:
 an input;   an output;   a first gear unit including a carrier drivable connected to the input, a nonrotating pinion that revolves with the carrier and meshes with a first gear unit output, the first gear unit producing a gear ratio of a speed of the input and a speed of the first gear unit output greater than unity;   a second gear unit including first and second sun gears, a first ring gear, a first carrier, and first planet pinions supported on the first carrier and engaged with the first sun gear, second sun gear and first ring gear;   a third gear unit including a third sun gear, a second ring gear, a second carrier, and second planet pinions supported on the second carrier and engaged with the third sun gear and second ring gear;   the second carrier and first ring gear being driveably connected to the output, the second sun gear and third sun gear being mutually driveably connected;   a first clutch being operable alternately to connect and disconnect the first gear unit output and the second ring gear;   a second clutch being operable alternately to connect and disconnect the first gear unit output to the second and third sun gears;   a third clutch being operable alternately to connect and disconnect the input and the first carrier;   a fourth clutch being operable alternately to connect and disconnect the input and the first sun gear;   a first brake being operable alternately to release and to hold the first sun gear against rotation; and   a second brake being operable alternately to release and to hold the first carrier against rotation.   
   
   
       15 . The transmission of  claim 14 , wherein:
 a low-reverse gear having a first reverse speed ratio is produced when the second clutch and second brake are engaged.   
   
   
       16 . The transmission of  claim 14 , wherein:
 a low-reverse gear having a second reverse speed ratio less than the first reverse speed ratio is produced when the fourth clutch and second brake are engaged.