Methodology for controlling a hydraulic control system of a continuously variable transmission

Patent metadata

Field	Value
Publication number	US-9383009-B2
Application number	US-201514925391-A
Country	US
Kind code	B2
Filing date	Oct 28, 2015
Priority date	May 31, 2013
Publication date	Jul 5, 2016
Grant date	Jul 5, 2016

Abstract

A hydraulic control system for a CVT may include a pressure regulator subsystem, a ratio control subsystem, a torque converter control (TCC) subsystem, a clutch control subsystem, and is enabled for automatic engine start/stop (ESS) functionality. A system and method are provided for performing an engine auto-stop in a vehicle having a CVT transmission and using an accumulator to fill the pulleys and clutches of the CVT, at least in part, during engine restart.

First claim

The following is claimed:

1. A continuously variable transmission comprising:
a hydraulic control system;
a pump driven by the engine for supplying a pressurized hydraulic fluid to the hydraulic control system;
a first pulley pair with a first moveable pulley;
a second pulley pair with a second moveable pulley;
a first torque transmitting device;
a second torque transmitting device; and
a controller having a preprogrammed digital computer and memory for storing control logic, the control logic including a first control logic for commanding a first pulley target pressure to the first moveable pulley, a second control logic for commanding a second pulley target pressure to the second moveable pulley, a third control logic for commanding one of a first torque transmitting device fill target pressure to the first torque transmitting device or a second torque transmitting device fill target pressure to the second torque transmitting device, a fourth control logic for determining whether a first pulley actual pressure is equal to or greater than the first pulley target pressure, a fifth control logic for determining whether a second pulley actual pressure is equal to or greater than the second pulley target pressure, and a sixth control logic for commanding a first torque transmitting device engagement target pressure to the first torque transmitting device or a second torque transmitting device engagement target pressure to the second torque transmitting device if the first pulley actual pressure is equal to or greater than the first pulley target pressure or the second pulley actual pressure is equal to or greater than the second pulley target pressure.

2. The continuously variable transmission of claim 1 wherein the controller further includes a seventh control logic for holding either the first torque transmitting device at the first torque transmitting device fill target pressure or the second torque transmitting device at the second torque transmitting device fill target pressure until the first pulley actual pressure is equal to or greater than the first pulley target pressure or the second pulley actual pressure is equal to or greater than the second pulley target pressure.

3. The continuously variable transmission of claim 2 wherein the first torque transmitting device fill target pressure is defined as a pressure in the first torque transmitting device insufficient to engage and transmit torque through the first torque transmitting device and the second torque transmitting device fill target pressure is defined as a pressure in the second torque transmitting device insufficient to engage and transmit torque through the second torque transmitting device.

4. The continuously variable transmission of claim 3 wherein the first torque transmitting device engagement target pressure is defined as a pressure in the first torque transmitting device sufficient to engage and transmit torque through the first torque transmitting device and the second torque transmitting device engagement target pressure is defined as a pressure in the second torque transmitting device sufficient to engage and transmit torque through the second torque transmitting device.

5. The continuously variable transmission of claim 4 wherein the first pulley actual pressure is a pressure of hydraulic fluid acting on the first moveable pulley and the second pulley actual pressure is a pressure of hydraulic fluid acting on the second moveable pulley.

6. A system in a motor vehicle comprising:
an engine;
a continuously variable transmission having:
a hydraulic control system;
a pump driven by the engine for supplying a pressurized hydraulic fluid to the hydraulic control system;
an accumulator;
a first pulley pair with a first moveable pulley;
a second pulley pair with a second moveable pulley;
a first clutch;
a second clutch; and
a controller having a preprogrammed digital computer and memory for storing control logic, the control logic including a first control logic for receiving an engine on command, a second control logic for commanding the accumulator to open if the engine on command has been received by the controller, a third control logic for commanding a first pulley target pressure to the first moveable pulley, a fourth control logic for commanding a second pulley target pressure to the second moveable pulley, a fifth control logic for commanding one of a first clutch fill target pressure to the first clutch or a second clutch fill target pressure to the second clutch, a sixth control logic for determining whether a first pulley actual pressure is equal to or greater than the first pulley target pressure, a seventh control logic for determining whether a second pulley actual pressure is equal to or greater than the second pulley target pressure, and an eighth control logic for commanding one of a first clutch engagement target pressure to the first clutch or a second clutch engagement target pressure to the second clutch if the first pulley actual pressure is equal to or greater than the first pulley target pressure and the second pulley actual pressure is equal to or greater than the second pulley target pressure.

7. The system of claim 6 further comprising a ninth control logic for holding either the first clutch at the first clutch fill target pressure or the second clutch at the second clutch fill target pressure until the first pulley actual pressure is equal to or greater than the first pulley target pressure and the second pulley actual pressure is equal to or greater than the second pulley target pressure.

8. The system of claim 6 wherein the first clutch fill target pressure is defined as a pressure in the first clutch insufficient to engage and transmit torque through the first clutch and the second clutch fill target pressure is defined as a pressure in the second clutch insufficient to engage and transmit torque through the second clutch.

9. The system of claim 6 wherein the first pulley actual pressure is a pressure of hydraulic fluid acting on the first moveable pulley and the second pulley actual pressure is a pressure of hydraulic fluid acting on the second moveable pulley.

10. The system of claim 6 further comprising a tenth control logic for commanding the accumulator to close if the engine has reached an idle speed and the first pulley actual pressure is equal to or greater than the first pulley target pressure, the second pulley actual pressure is equal to or greater than the second pulley target pressure, and one of the first clutch engagement target pressure is greater than or equal to a first clutch engagement actual pressure and the second clutch engagement target pressure is equal to or greater than a second clutch engagement actual pressure.

11. The system of claim 6 further comprising:
an eleventh control logic for determining an accumulator stored volume;
a twelfth control logic for determining whether the accumulator stored volume is equal to an accumulator fill volume;
a thirteenth control logic for determining whether a motor vehicle stop has occurred;
a fourteenth control logic for determining whether an engine auto-stop is allowed based on motor vehicle conditions;
a fifteenth control logic for determining whether to inhibit the engine auto-stop based on transmission conditions; and
a sixteenth control logic for commanding an engine auto-stop if the accumulator stored volume is equal to the accumulator fill volume, the motor vehicle has stopped, the engine auto-stop is allowed, and the engine auto-stop has not been inhibited.

12. The system of claim 11 wherein the motor vehicle conditions include a cabin air conditioning status, an ambient tempe

Assignees

• Gm Global Tech Operations Inc
• Gm Global Tech Operations Inc

Inventors

• Lundberg Philip C
• Marin Carlos E

Classifications

• F16H9/18

  only one flange of each pulley being adjustable · CPC title

• F16H61/66272 Primary

  characterised by means for controlling the torque transmitting capability of the gearing · CPC title

• F16H61/0031

  using auxiliary pumps, e.g. pump driven by a different power source than the engine · CPC title

• F16H2061/0034

  Accumulators for fluid pressure supply; Control thereof · CPC title

• F16H61/66254

  controlling of shifting being influenced by a signal derived from the engine and the main coupling · CPC title