METHOD AND SYSTEM FOR CONTROLLING RATE OF CHANGE OF RATIO IN A CONTINUOUSLY VARIABLE TRANSMISSION

• US 20100280722A1
• Filed: 04/05/2010
• Published: 11/04/2010
• Est. Priority Date: 03/19/2003
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Dreumont, Thomas, Frank, Andrew A.
• Granted Patent: US 8,057,354 B2
• Time in Patent Office: Days
• US Class Current: 701/55
• CPC Class Codes: B60K 6/36 characterised by the transmission gearings
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2260/14 of transmissions
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 10/107 with endless flexible members
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2710/0672 Torque change rate
• CPC Class Codes: B60W 2710/1055 Output torque change rate
• CPC Class Codes: B60W 2720/106 Longitudinal acceleration
• CPC Class Codes: F16H 2059/702 Rate of change of gear ratio, e.g. for triggering clutch engagement
• CPC Class Codes: F16H 2061/66277 by optimising the clamping force exerted on the endless flexible member
• CPC Class Codes: F16H 61/66254 : controlling of shifting being influenced by a signal derived from the engine and the main coupling
• CPC Class Codes: F16H 61/66272 : characterised by means for controlling the torque transmitting capability of the gearing
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles

Abstract

Systems and methods for efficiently and effectively controlling the rate of change of ratio, not simply the ratio, in a CVT. By controlling the rate of change of ratio, the acceleration or deceleration of a vehicle can be controlled in an efficient manner. Furthermore, the rate of change of ratio can be controlled by controlling the clamping pressure of the pulleys and/or differential pressure between the pulleys with minimal slip by using a servo control mechanism adapted for control by a system controller based on equilibrium mapping and other control parameters.

Claims

1. A method for controlling the operation of a continuously variable transmission (CVT), comprising:

mapping rate of change of ratio to clamping pressure and/or differential pressure between pulleys in said CVT;

controlling clamping pressure and/or differential pressure between pulleys in said CVT based on said mapping; and

applying a torque clipping algorithm adapted to throttle back the torque to the primary pulley when the clamping pressure is insufficient.

2. A method for optimizing the operation of a continuously variable transmission (CVT), comprising:

accessing a map of the relationship between pressure of a CVT and rate of change of ratio to transmit a given amount of torque;

controlling primary and second pulley pressure of the CVT to achieve a commanded clamping pressure for commanded torque and ratio rate based on said map; and

applying a torque clipping algorithm adapted to throttle back the torque to the primary pulley when the clamping pressure is insufficient.

3. A method for optimizing the operation of a continuously variable transmission (CVT), comprising:

controlling primary and secondary pulley pressures of the CVT to control the ratio rate and/or ratio and clamping pressure of the CVT based on an equilibrium ratio map of the CVT specifying the relationship between the ratio of primary and secondary clamping forces, torque ratio and geometric ratio of the transmission; and

applying a torque clipping algorithm adapted to throttle back the torque to the primary pulley when the clamping pressure is insufficient.

4. A method for controlling the operating of a continuously variable transmission (CVT) comprising:

providing a servo control system;

said servo control system configured to control clamping pressure and differential pressure between primary and secondary pulleys in the CVT;

controlling said servo control system to achieve commanded clamping pressure and/or differential pressure between the primary and secondary pulleys based on a mapping of rate of change of ratio of said CVT to said clamping pressure and/or differential pressure between pulleys; and

applying a torque clipping algorithm adapted to throttle back the torque to the primary pulley when the clamping pressure is insufficient.