Seven-speed power transmission

• US 6,766,705 B1
• Filed: 01/24/2003
• Issued: 07/27/2004
• Est. Priority Date: 01/24/2003
• Status: Active Grant

• Current Assignee: Allison Transmission Incorporated (Allison Transmission Holdings Incorporated)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Hall, Arthur III
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US10/350,440
• Publication Number:
  US 20040144190A1
• Time in Patent Office: 550 Days
• Field of Search: 743/31, 743/39
• US Class Current: 74/331
• CPC Class Codes: F16H 2003/0931 each countershaft having an output gear meshing with a single common gear on the output shaft
• CPC Class Codes: F16H 2003/123 using a brake
• CPC Class Codes: F16H 2061/0411 by control of shaft brakes
• CPC Class Codes: F16H 2200/0056 the gear ratios comprising seven forward speeds
• CPC Class Codes: F16H 2306/48 Synchronising of new gear
• CPC Class Codes: F16H 3/006 power being selectively transmitted by either one of the parallel flow paths
• CPC Class Codes: F16H 3/12 with means for synchronisation not incorporated in the clutches
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: F16H 61/688 with two inputs, e.g. selection of one of two torque-flow paths by clutches
• CPC Class Codes: Y10T 74/19233 Plurality of counter shafts
• CPC Class Codes: Y10T 74/19284 Meshing assisters

Abstract

A power transmission includes a pair of input clutches, a plurality of ratio gear mechanisms, and an output shaft. The ratio gear mechanisms are selectively connected with respective countershafts to complete power flows between the transmission input and transmission output and one or the other of the input clutches. During a ratio upshift, a brake mechanism is connected with each of the input clutches to control the speed of the shafts connected therewith when the clutches are disengaged and an upshift condition is being preselected.

Claims

1. A power transmission for use in a powertrain having an engine comprising:

a first selectively engageable and disengageable input clutch;

a second selectively engageable and disengageable input clutch;

a first shaft selectively connectable with the engine by said first selectively engageable and disengageable input clutch;

a second shaft selectively connectable with the engine by said second selectively engageable and disengageable input clutch;

a first plurality of ratio gears drivingly connected with said first shaft;

a first countershaft;

a second plurality of ratio gears rotatably mounted on said first countershaft and meshing with respective ones of said first plurality of ratio gears;

first mechanical clutch means for selectively interconnecting each of said second plurality of ratio gears to said first countershaft;

a third plurality of ratio gears drivingly connected with said second shaft;

a second countershaft;

a fourth plurality of ratio gears rotatably mounted on said second countershaft;

a second mechanical clutch means for selectively interconnecting each of said fourth plurality of ratio gears with said second countershaft;

a first brake means operatively connected with one of said second plurality of ratio gears for controlling the speed of said first shaft when said first selectively engageable and disengageable clutch is disengaged;

a second brake means operatively connected with one of said fourth plurality of ratio gears for controlling the speed of said second shaft when said second selectively engageable and disengageable clutch is disengage;

said second brake means being operated during preselection of upshifts to ratios through said second countershaft to control the speed of said second countershaft when said first countershaft is transmitting power; and

said first brake means being operated during preselection of upshifts to ratios through said first countershaft to control the speed of said first countershaft when said second countershaft is transmitting power;

an output shaft continuously interconnected with said first and second countershafts through output gear means.

2. The power transmission defined in claim 1 further comprising:

said first and second brake means being inoperative during downshift ratio interchanges.

3. The power transmission defined in claim 2 further comprising third mechanical clutch means for directly connecting the engine with a transmission output shaft through one of said input clutches.

4. The power transmission defined in claim 3 further comprising:

first output gear means disposed between said first countershaft and said transmission output shaft; and

second output gear means disposed between said second countershaft and said transmission output shaft.

5. The power transmission defined in claim 2 further comprising:

a first gear member rotatably mounted on said second shaft;

a second gear member rotatable with said second countershaft and meshing with said first gear member; and

a fourth mechanical clutch means for selectively connecting said first gear member with said second shaft.