Detection of an exhausting clutch in a neutral idle-equipped transmission

Patent metadata

Field	Value
Publication number	US-9316308-B2
Application number	US-201414517259-A
Country	US
Kind code	B2
Filing date	Oct 17, 2014
Priority date	Apr 18, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A transmission assembly for a vehicle includes a transmission and a controller. The transmission includes an input member, at least one clutch and gear set, and an output member. The input member receives an input torque from an engine. The output member receives an output torque from the clutch and gear set(s). The clutch and gear set(s) connect to the input member and establish a plurality of operating states including a neutral idle (NI) state. A designated NI clutch is selectively actuated to enter the NI state when the transmission is in a drive state and the vehicle is stationary. The controller calculates a reference slip error as a function of engine and turbine speed, and detects when the designated NI clutch is exhausting fluid while operating in the NI state using a function of the reference slip error. A control action executes when the exhausting NI clutch is detected.

First claim

The invention claimed is:

1. A transmission assembly for a vehicle having an engine and a torque converter having a turbine, the transmission assembly comprising:
a transmission having:
an input member configured to receive an input torque from the engine;
at least one clutch and gear set operable to establish a plurality of operating states of the transmission including a neutral idle (NI) state, wherein the at least one clutch and gear set includes a designated NI clutch that is selectively actuated to enter the NI state when the transmission is in a drive state and the vehicle is stationary;
an output member that receives an output torque from the at least one clutch and gear set for propelling the vehicle; and

a controller configured to:
calculate a reference slip error as a function of a speed of the engine and a speed of the turbine;
detect when the designated NI clutch is exhausting fluid while operating in the NI state using the reference slip error; and
execute a control action with respect to the transmission when the designated NI clutch is detected as exhausting fluid.

2. The transmission assembly of claim 1 , wherein the controller is configured to determine a clutch pressure of the designated NI clutch and to detect when the designated NI clutch is exhausting fluid as a function of the determined clutch pressure and the calculated reference slip error.

3. The transmission assembly of claim 2 , wherein the controller is configured to determine when the calculated reference slip error is stable while the determined clutch pressure of the designated NI clutch is decreasing, and to thereby detect when the designated NI clutch is exhausting fluid.

4. The transmission assembly of claim 1 , wherein the designated NI clutch is a braking clutch.

5. The transmission assembly of claim 4 , wherein the transmission is an 8-speed transmission.

6. The transmission assembly of claim 5 , wherein the plurality of operating states includes 1 st , 2 nd , 7 th , 8 th , and reverse gear and the designated NI clutch is engaged in each of the 1 st , 2 nd , 7 th , 8 th , and reverse gears.

7. The transmission assembly of claim 4 , wherein the transmission is a 6-speed transmission.

8. The transmission assembly of claim 7 , wherein the plurality of operating states includes 1 st , 2 nd , 3 rd , and 4 th gear and the designated NI clutch is engaged in each of the 1 st , 2 nd , 3 rd , and 4 th gears.

9. The transmission assembly of claim 1 , wherein the controller is programmed with a calibrated torque converter slip profile of the vehicle that is used to control slip across the torque converter in the NI state and in the park/neutral (P/N) state, and wherein the control action includes:
automatically adjusting the calibrated torque converter slip profile; and
controlling the transmission in a subsequent NI state using the adjusted slip curve.

10. The transmission assembly of claim 1 , wherein the control action includes setting a diagnostic code in memory of the controller.

11. The transmission assembly of claim 1 , wherein the control action includes adjusting only a portion of a calibrated torque converter slip curve, and then controlling the transmission in a subsequent NI state using the slip curve with the adjusted portion.

12. A transmission assembly for a vehicle having an engine and a torque converter having a turbine, the transmission comprising:
a transmission having:
a plurality of rotating clutches and a plurality of braking clutches, wherein the plurality of braking clutches includes a designated neutral idle (NI) clutch;
at least three gear sets that are configured, via actuation of at least some of the clutches, to establish a plurality of different operating states of the transmission, including an NI state that is entered when the transmission is in a drive state and the vehicle is stationary;
an output member that receives an output torque from one of the plurality of gear sets for propelling the vehicle; and

a controller configured to:
calculate a reference slip error as a function of a speed of the engine and a speed of the turbine;
detect when the designated NI clutch is exhausting fluid while operating in the NI state using a function of the reference slip error; and
execute a control action with respect to the transmission when the NI clutch is detected as exhausting fluid.

13. The transmission assembly of claim 11 , wherein the controller is configured to determine a clutch pressure of the designated NI clutch and to detect when the designated NI clutch is exhausting fluid as a function of the determined clutch pressure and the calculated reference slip error.

14. The transmission assembly of claim 12 , wherein the controller is configured to determine when the calculated reference slip error is stable while the determined clutch pressure of the designated NI clutch is decreasing, and thereby detect when the designated NI clutch is exhausting fluid.

15. The transmission assembly of claim 12 , wherein the designated NI clutch and the output member are connected to different nodes of the same gear set of the plurality of gear sets.

16. The transmission assembly of claim 15 , wherein the transmission is a 6-speed transmission and the designated NI clutch is further engaged in 1 st , 2 nd , 3 rd , and 4 th gear.

17. The transmission assembly of claim 12 , wherein the designated NI clutch and the output member are connected to different gear sets of the plurality of gear sets.

18. The transmission assembly of claim 16 , wherein the transmission is an 8-speed transmission and the designated NI clutch is further engaged in 1 st , 2 nd , 7 th , 8 th , and reverse gear.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Lochocki Jr Ronald F
• Sebastian Sindu
• Kim Min K

Classifications

• F16H2061/207

  by neutral control · CPC title

• F16H2061/1208

  with diagnostic check cycles; Monitoring of failures · CPC title

• F16H61/0204 Primary

  for gearshift control, e.g. control functions for performing shifting or generation of shift signal · CPC title

• F16H61/20

  Preventing gear creeping {; Transmission control during standstill, e.g. hill hold control} · CPC title

• B60W10/02

  including control of driveline clutches · CPC title