Control device of continuously variable transmission

• US 6,723,014 B2
• Filed: 03/20/2001
• Issued: 04/20/2004
• Est. Priority Date: 03/21/2000
• Status: Expired due to Fees

• Current Assignee: Transtechnology Ltd.
• Original Assignee: Jatco Transtechnology Limited
• Inventors: Shinso, Yoshihide, Sakakibara, Satoshi, Miyagawa, Yoshikazu
• Primary Examiner(s): SICONOLFI, ROBERT
• Application Number:
  US09/810,608
• Publication Number:
  US 20010027147A1
• Time in Patent Office: 1,127 Days
• Field of Search: 474/18, 474/20
• US Class Current: 474/20
• CPC Class Codes: B60K 6/36 characterised by the transmission gearings
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• 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 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• 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 2050/021 Means for detecting failure or malfunction
• CPC Class Codes: F16H 2061/1248 Resuming normal operation
• CPC Class Codes: F16H 2061/1292 the failing part is the power supply, e.g. the electric power supply
• CPC Class Codes: F16H 2312/02 Driving off
• CPC Class Codes: F16H 2312/20 Start-up or shut-down
• 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 61/662 with endless flexible members
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/918 Continuously variable
• CPC Class Codes: Y10S 903/945 Characterized by control of gearing, e.g. control of transmission ratio

Abstract

A transmission mechanism of continuously variable transmission in a vehicle comprises a primary pulley and a secondary pulley provided with a first cylinder chamber and a second cylinder chamber, with groove widths being changed by supply of hydraulic pressure, and a belt provided between the pulleys. A hydraulic pressure to the first cylinder chamber is controlled by CVT control unit through a shift control valve according to a driving state of the vehicle, and the second cylinder chamber is continuously supplied with a line pressure. CVT control unit includes an internal memory to retain a heavy-current system fail flag according to the failure information inputted from a motor control unit. If, at start of driving, the internal memory holds failure information indicating that the electric motor driving a hydraulic pump fails in previous driving, CVT control unit outputs a shift command targeting a high range ratio for a predetermined time to thereby fill the first cylinder chamber with hydraulic pressure, and thereafter outputs a shift command targeting a normal gear ratio according to the driving state.

Claims

1. A control device of a continuously variable transmission in a vehicle, which control device comprises:

a transmission mechanism comprising a primary pulley and a secondary pulley provided with a first cylinder chamber and a second cylinder chamber, with groove widths being changed by supply of hydraulic pressure respectively, and a belt provided between said primary pulley and said secondary pulley;

a hydraulic pump being driven by an electric motor to supply hydraulic pressure;

line pressure control means for regulating hydraulic pressure from said hydraulic pump to predetermined line pressure and continuously supplying said line pressure to said second cylinder chamber;

a shift control valve being driven by an actuator to supply hydraulic pressure, whose original pressure is line pressure, to said first cylinder chamber; and

shift control means for outputting a shift command for controlling said actuator according to a driving state, said control device of the continuously variable transmission comprising;

failure information holding means for holding failure information concerning a failure of said electric motor; and

wherein if, at start of driving, said failure information holding means holds failure information indicating that said electric motor failed in previous driving, said shift control means outputs a shift command targeting a high range ratio for a predetermined period of time before the start of driving to thereby fill said first cylinder chamber of said primary pulley with hydraulic pressure, and starts outputting a shift command targeting a normal gear ratio according to the driving state after a predetermined vehicle speed is reached after the start of driving.

2. A control device of a continuously variable transmission according to claim 1, wherein:

a motor control unit controls said electric motor;

said failure information holding means is an internal memory of said shift control means, said internal memory retaining a heavy-current system fail flag according to the failure information inputted from said motor control unit;

and said heavy-current system fail flag is reset after said predetermined vehicle speed is reached.