Engine CVT control system

• US 5,047,937 A
• Filed: 06/01/1990
• Issued: 09/10/1991
• Est. Priority Date: 06/01/1990
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Linzell, Samuel M., Vahabzadeh, Hamid
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/531,676
• Time in Patent Office: 466 Days
• Field of Search: 74/866, 74/857, 74/865, 364/424.1
• US Class Current: 701/54
• 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 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 2302/00 Determining the way or trajectory to new ratio, e.g. by determining speed, torque or time parameters for shift transition
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38

Abstract

A control system for an engine-CVT drivetrain controls the ratio rate of the CVT to control the speed of the vehicle engine, providing a means for improved control over the transient response of the engine-CVT drivetrain.

Claims

1. In a CVT control system, for a vehicle drivetrain with an engine having various engine speeds, including ratio control means having an input element positionable in response to a control signal to establish various speed ratios between input and output shafts of the CVT and various ratio rates of the CVT and controller means developing the control signal for positioning the input element in response to operator demand, the improvement wherein the controller means (1) develops a command indicative of a desired engine speed in response to operator power demand, (2) compares the command to a measure of the actual engine speed, (3) develops the control signal in a manner determined as a function of the comparison, and (4) applies the control signal to the input element, affecting a direct control of the ratio rate and hence engine speed, in response to the operator demand.

2. In a powertrain control system including an engine having engine speed and a positionable throttle, a CVT including a ratio control means having an input element positionable in response to a control signal to establish various speed ratios between input and output shafts of the CVT and various ratios rates of the CVT, and controller means developing the control signal for positioning the CVT input element and the throttle in response to operator demand, the improvement wherein:

the controller generates desired engine speed and throttle position commands in response to operator power demand;

the controller positions the throttle to said desired throttle position, thereby controlling engine torque;

the controller compares the desired engine speed to a measure of the actual engine speed;

the controller develops the control signal in a manner determined as a function of the comparison; and

the controller applies the control signal to the input element to affect a direct control of the ratio rate, and hence engine speed, in response to the operator demand.

3. A control method for a vehicle drivetrain including a variable speed engine and a CVT including a ratio control element positionable in response to a control signal to establish various speed ratios between input and output shafts of the CVT and various ratio rates of the CVT, the control method comprising the steps of:

developing a command indicative of a desired engine speed in response to operator power demand;

comparing the command to a measure of the actual engine speed;

developing a control signal in a manner determined as a function of the comparison; and

applying the control signal to the ratio control element to affect a direct control of the ratio rate and hence engine speed, in response to operator demand.

4. A control method for a vehicle drivetrain including a variable speed engine having a positionable throttle and a CVT having a ratio control element positionable in response to a control signal to establish various speed ratios between input and output shafts of the CVT and various ratio rates of the CVT, the control method comprising the steps of:

developing a command indicative of a desired engine speed in response to operator power demand;

comparing the command to a measure of the actual engine speed;

developing a control signal in a manner determined as a function of the comparison; and

applying the control signal to the ratio control element to affect a direct control of the ratio rate and, in conjunction with throttle position, a direct control of engine speed, in response to operator demand.

5. A control method for a vehicle drivetrain including a variable speed engine having a positionable throttle and a CVT having a ratio control element positionable in response to a control signal to establish various speed ratios between input and output shafts of the CVT and various ratio rates of the CVT, the control method comprising the steps of:

developing desired engine speed and throttle position commands in response to operator power demand;

positioning the throttle to said desired throttle position, thereby controlling engine torque and affecting engine speed;

comparing the desired engine speed to a measure of the actual engine speed;

developing a control signal in a manner determined as a function of the comparison; and

applying the control signal to the ratio control element to affect a direct control of the ratio rate and, in conjunction with throttle position, a direct control over engine speed, in response to the operator demand.