Method and system using fuzzy logic for controlling a CVT transmission

• US 5,558,596 A
• Filed: 10/25/1994
• Issued: 09/24/1996
• Est. Priority Date: 11/19/1990
• Status: Expired due to Fees

• Current Assignee: Hitachi Automotive Engineering Incorporated (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Automotive Engineering Incorporated (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Sato, Kazuhiko, Ohkubo, Minoru, Adachi, Masao, Shioya, Makoto
• Primary Examiner(s): TA, KHOI QUANG
• Application Number:
  US08/328,535
• Time in Patent Office: 700 Days
• Field of Search: 477/45, 477/46, 477/48, 477/49, 364/424.1
• US Class Current: 701/57
• CPC Class Codes: B60W 2050/0057 Frequency analysis, spectral techniques or transforms
• CPC Class Codes: F16H 2061/0081 Fuzzy logic
• CPC Class Codes: F16H 59/24 dependent on the throttle opening
• CPC Class Codes: F16H 59/36 Inputs being a function of speed
• CPC Class Codes: F16H 59/40 Output shaft speed
• CPC Class Codes: F16H 59/42 Input shaft speed
• CPC Class Codes: F16H 59/48 Inputs being a function of acceleration
• CPC Class Codes: F16H 61/66259 using electrical or electronical sensing or control means

Abstract

According to the present invention, the driver'"'"'s operation quantity and the vehicle running status are measured, the target value of speed ratio or the target value of revolution speed on the input side of the transmission is determined on the basis of the above measured values, and the speed ratio is changed using different algorithms (particularly fuzzy rules) on the basis of the magnitude of deviation between the target value and the actual value.

Furthermore, when a vehicle has a continuously variable transmission, a change of at least one of the vehicle acceleration and the shaft torque of a drive wheel is predicted, the engine output torque is controlled on the basis of the prediction, and finite speed ratio characteristics or intermediate characteristics between finite speed ratio characteristics and continuously variable speed ratio characteristics are controlled for the continuously variable transmission. By doing this, speed ratio control stressed on stability is available when the absolute value of the above deviation is small, while speed ratio control stressed on rapid response and smooth acceleration variation is available when the absolute value of the deviation is large.

Furthermore, a smooth acceleration feeling and a rapid acceleration response can be realized, the maneuverability is improved, and the driver can find pleasure in more speed ratio characteristics.

Claims

1. In a vehicle transmission system including an operation sensor, a running status sensor, a processor and a memory storing relation data between target speed and data measured by use of said operation sensor and said running status sensor, a speed ratio control method for a continuously variable transmission which transfer inputs from a power source to a drive wheel, comprising the steps of;

measuring through said operation and said running status sensors, a driver'"'"'s operation quantity and a vehicle running status;

determining through said processor, by use of said relation data, one of a target value of speed ratio and a target value of revolution speed on an input of said transmission on a basis of results of said measuring step; and

changing a speed ratio using at least two different algorithms in correspondence with whether or not a value of deviation between said target value and a current actual value is greater than a threshold value.

2. A speed ratio control method for a transmission according to claim 1, wherein a changing in said changing step is performed on a deviation and velocity of deviation variation when an absolute value of said deviation is smaller than a predetermined value.

3. In a vehicle transmission system including an operation sensor, a running status sensor, a processor and a memory storing relation data between target speed and data measured by use of said operation sensor and said running status sensor, a speed ratio control method for a continuously variable transmission which transfer inputs from a power source to a drive wheel, comprising the steps of;

measuring through said operation and said running status sensors, a driver'"'"'s operation quantity and a vehicle running status;

determining through said processor, by use of said relation data, one of a target value of speed ratio and a target value of revolution speed on an input of said transmission on a basis of results of said measuring step; and

changing a speed ratio using at least two different algorithms in correspondence with whether or not a value of deviation between said target value and a current actual value is greater than a threshold value;

wherein at least one of said different algorithms uses fuzzy logic rules.

4. In a vehicle transmission system including an operation sensor, a running status sensor, a processor and a memory storing relation data between target speed and data measured by use of said operation sensor and said running status sensor, a speed ratio control method for a continuously variable transmission which transfer inputs from a power source to a drive wheel, comprising the steps of;

measuring through said operation and said running status sensors, a driver'"'"'s operation quantity and a vehicle running status;

determining through said processor, by use of said relation data, one of a target value of speed ratio and a target value of revolution speed on an input of said transmission on a basis of results of said measuring step; and

changing a speed ratio using at least two different algorithms in correspondence with whether or not a value of deviation between said target value and a current actual value is greater than a threshold value;

wherein said changing step is performed according to when an absolute value of said deviation is larger than a predetermined value, said speed ratio is changed based on an at least one of a vehicle acceleration value, and a value which is at least one of a ratio and difference between a predicted time until said deviation becomes 0, and a predicted response time necessary for stopping a speed by use of a speed ratio control actuator.

5. In a vehicle transmission system including an operation sensor, a running status sensor, a processor and a memory storing relation data between target speed and data measured by use of said operation sensor and said running status sensor, a speed ratio control method for a continuously variable transmission which transfer inputs from a power source to a drive wheel, comprising the steps of;

measuring through said operation and said running status sensors, a driver'"'"'s operation quantity and a vehicle running status;

determining through said processor, by use of said relation data, one of a target value of speed ratio and a target value of revolution speed on an input of said transmission on a basis of results of said measuring step; and

changing a speed ratio using at least two different algorithms in correspondence with whether or not a value of deviation between said target value and a current actual value is greater than a threshold value;

wherein said changing step further comprises;

when both an acceleration pedal position variation velocity and an absolute value of said deviation between said target value and the actual value are smaller than predetermined values, said speed ratio is not changed.

6. In a vehicle including an operation sensor, a running status sensor, a processing means and a memory storing relation data between target speed and data measured by use of said operation sensor and said running status sensor, a speed ratio control system of a continuously variable transmission which transfers inputs from a power source to a drive wheel, comprising:

means for measuring a driver'"'"'s operation quantity and a vehicle running status;

means for determining one of a target value of speed ratio and a target value of revolution speed on an input of said transmission on a basis of results from said means for measuring; and

means for changing a speed ratio using at least two different algorithms in correspondence with whether or not a value of deviation between said target value and a current actual value is greater than a threshold value.