Method of controlling clutch pressure of continuously variable transmission system

• US 4,856,380 A
• Filed: 08/08/1988
• Issued: 08/15/1989
• Est. Priority Date: 08/10/1987
• Status: Expired due to Term

• Current Assignee: Suzuki Motor Corporation
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Suzuki Jidosha Kogyo Kabushiki Kaisha
• Inventors: Yamashita, Yoshinori, Yamamoto, Hiroaki, Tatsumi, Takumi, Hirano, Sadayuki, Murano, Katsuaki
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/229,893
• Time in Patent Office: 372 Days
• Field of Search: 74/866, 74/867, 74/858, 192/30 W, 192/3.58, 364/424.1
• US Class Current: 477/39
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• 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 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 61/66259 using electrical or electronical sensing or control means

Abstract

A method of controlling clutch pressure in a continuously variable transmission system which can expand and contract the width of a channel between a stationary pulley member and a movable pulley member movable relative to the stationary pulley member in order to respectively contract and expand a radius of travel about the pulleys of a belt engaging the pulleys before eventually varying a belt ratio, a clutch-pressure control arrangement of the continuously variable transmission system including a controller unit which effects control by feeding an actually-detected clutch pressure back in determining an objective clutch pressure and including an oil-pressure circuit which controls oil pressure in response to signals from the controller unit; the method comprising the step of: causing the controller unit to calculate a clutch duty ratio in reference to the objective clutch pressure and an objective line pressure when a pressure sensor detecting the actually-detected clutch pressure outputs an abnormal signal before eventually causing the controller unit to control the clutch pressure in accordance with the calculated clutch duty ratio.

Claims

1. A method of controlling clutch pressure in a continuously variable transmission system which can expand and contract a width of a channel between a stationary pulley member and a movable pulley movable relative to said stationary pulley member in order to respectively contract and expand a radius of travel about said pulleys of a belt engaging said pulleys before eventually varying a belt ratio, clutch-pressure control means of said continuously variable transmission system including a controller unit which effects control by feeding an actually-detected clutch pressure back in determining an objective clutch pressure and including an oil-pressure circuit which controls oil pressure in response to signals from said controller unit;

said method comprising a step of;

causing said controller unit to calculate a clutch duty ratio in reference to the objective clutch pressure and an objective line pressure when a pressure sensor detecting said actually-detected clutch pressure outputs an abnormal signal before eventually causing said controller unit to control the clutch pressure in accordance with said calculated clutch duty ratio.

2. The method of claim 1, including the step of determining that said pressure sensor is outputting abnormal signals when signals therefrom are outside a predetermined range bounded by predetermined upper and lower limits.