Method for monitoring a continuously variable transmission

• US 6,595,896 B1
• Filed: 06/07/2001
• Issued: 07/22/2003
• Est. Priority Date: 12/17/1998
• Status: Expired due to Fees

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Batavia Transmission LLC (Ford Motor Company)
• Inventors: Gierling, Armin
• Primary Examiner(s): Bonck, Rodney H.
• Assistant Examiner(s): PANG, ROGER L
• Application Number:
  US09/857,595
• Time in Patent Office: 775 Days
• Field of Search: 477/39, 477/41, 477/45, 477/46, 477/47, 477/91, 477/110, 477/175
• US Class Current: 477/39
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 10/107 with endless flexible members
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 2061/0477 by suppression of excessive engine flare or turbine racing during shift transition engine flare caused by lock-up release F16H61/143
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/1232 Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios
• CPC Class Codes: F16H 2061/124 Limiting the input power, torque or speed
• CPC Class Codes: F16H 2061/1264 Hydraulic parts of the controller, e.g. a sticking valve or clogged channel
• CPC Class Codes: F16H 61/0021 Generation or control of line pressure
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: F16H 61/66272 characterised by means for controlling the torque transmitting capability of the gearing
• CPC Class Codes: F16H 63/40 comprising signals other than signals for actuating the final output mechanisms

Abstract

The method for monitoring the system pressure of a continuously variable transmission for motor vehicles which, via a permanent mechanical connection, is connected with the prime mover of the motor vehicle consists in that a warning signal is activated for the driver when a drop in system pressure is detected, an entry is made in the transmission fault memory, the clutch on the output side is opened, a signal is sent to the electronic engine control system to prevent uncontrolled acceleration of the engine and the vehicle speed is monitored until it falls below a preset threshold value after which the engine is switched off.

Claims

1. A method for monitoring a system pressure of a continuously variable transmission (CVT) for a motor vehicle which is connected on one side, via a permanent mechanical connection, with an engine of the vehicle and on the other side, via an output line, with gears of the motor vehicle, the method comprising the steps of:

a) monitoring continuously the system pressure in the CVT;

b) communicating to an operator of said motor vehicle a system pressure drop;

c) entering a system pressure drop in a transmission fault memory;

d) opening a clutch on an output side;

e) communicating to an electronic engine control a signal to prevent an uncontrolled acceleration of the engine; and

f) monitoring a vehicle speed until it falls below a preset threshold value after which the engine is switched off.