Speed change control device for belt type continuously variable transmission and control method thereof

Abstract

A speed change control device for a belt type continuously variable transmission has a speed change control unit (32) which controls an oil pressure for determining a speed ratio of the continuously variable transmission (10) by operating a step motor (40), and detects a rotation speed of a primary pulley or a secondary pulley. A driving speed of the step motor (40) is limited using two or more of a temperature of a working oil of the speed change control unit (32), the speed ratio of the continuously variable transmission (10), and the detected rotation speed as parameters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a speed change control device for a belt type continuously variable transmission according to an embodiment.

FIG. 2 is a schematic diagram of an oil pressure control unit and a CVTCU.

FIG. 3 is a flowchart showing the control of the speed change control device for a belt type continuously variable transmission according to this embodiment.

FIG. 4 is a map showing the relationship between a primary rotation speed, a speed ratio, an oil temperature, and a drive frequency.

Claims

1. A speed change control device for a continuously variable transmission in which a belt is wrapped around a primary pulley into which an output of a drive source is input and a secondary pulley which is connected to an output side of a drive system of a vehicle, and which changes a rotation speed of the drive source continuously and outputs the rotation speed by altering a groove width of the primary pulley and the secondary pulley, the device comprising: a speed change oil pressure control unit which controls an oil pressure for determining a speed ratio of the continuously variable transmission by operating a motor, anda controller whichdetects a rotation speed of the primary pulley or the secondary pulley;limits a driving speed of the motor using two or more of a temperature of a working oil of the speed change oil pressure control unit, the speed ratio of the continuously variable transmission, and the detected rotation speed as parameters.

2. The speed change control device as defined in claim 1, wherein the controller which limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the speed ratio of the continuously variable transmission as parameters.

3. The speed change control device as defined in claim 1, wherein the controller which limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the detected rotation speed as parameters.

4. The speed change control device as defined in claim 1, wherein one of the two or more parameters is the speed ratio of the continuously variable transmission, and the controller which limits the driving speed to an increasingly lower speed as the speed ratio shifts toward a low side.

5. The speed change control device as defined in claim 1, wherein one of the two or more parameters is the detected rotation speed, and the controller which limits the driving speed to an increasingly lower speed as the detected rotation speed decreases.

6. The speed change control device as defined in claim 1, further comprising an engine as the drive source, wherein the controller which prohibits limitation of the driving speed when a throttle opening of the engine is smaller than a predetermined low opening.

7. A speed change control method for a continuously variable transmission in which a belt is wrapped around a primary pulley into which an output of a drive source is input and a secondary pulley which is connected to an output side of a drive system of a vehicle, which changes a rotation speed of the drive source continuously and outputs the rotation speed by altering a groove width of the primary pulley and the secondary pulley, and which includes a speed change oil pressure control unit which controls an oil pressure for determining a speed ratio of the continuously variable transmission by operating a motor, the method comprising: detecting a rotation speed of the primary pulley or the secondary pulley; andlimiting a driving speed of the motor using two or more of a temperature of a working oil of the speed change oil pressure control unit, the speed ratio of the continuously variable transmission, and the detected rotation speed as parameters.

8. The speed change control method as defined in claim 7, wherein the limiting a driving speed of the motor limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the speed ratio of the continuously variable transmission as parameters.

9. The speed change control method as defined in claim 7, wherein the limiting a driving speed of the motor limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the detected rotation speed as parameters.

10. The speed change control method as defined in claim 7, wherein one of the two or more parameters is the speed ratio of the continuously variable transmission, and the limiting a driving speed of the motor limits the driving speed to an increasingly lower speed as the speed ratio shifts toward a low side.

11. The speed change control method as defined in claim 7, wherein one of the two or more parameters is the detected rotation speed, and the limiting a driving speed of the motor limits the driving speed to an increasingly lower speed as the detected rotation speed decreases.

12. The speed change control method as defined in claim 7, further comprising an engine as the drive source, wherein the limiting a driving speed of the motor prohibits limitation of the driving speed when a throttle opening of the engine is smaller than a predetermined low opening.

13. A speed change control device for a continuously variable transmission in which a belt is wrapped around a primary pulley into which an output of a drive source is input and a secondary pulley which is connected to an output side of a drive system of a vehicle, and which changes a rotation speed of the drive source continuously and outputs the rotation speed by altering a groove width of the primary pulley and the secondary pulley, the device comprising: pulley rotation speed detecting means for detecting a rotation speed of the primary pulley or the secondary pulley;a speed change oil pressure control unit which controls an oil pressure for determining a speed ratio of the continuously variable transmission by operating a motor; anddriving speed limiting means for limiting a driving speed of the motor using two or more of a temperature of a working oil of the speed change oil pressure control unit, the speed ratio of the continuously variable transmission, and the rotation speed detected by the pulley rotation speed detecting means as parameters.

14. The speed change control device as defined in claim 13, wherein the driving speed limiting means limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the speed ratio of the continuously variable transmission as parameters.

15. The speed change control device as defined in claim 13, wherein the driving speed limiting means limits the driving speed of the motor using the temperature of the working oil of the speed change oil pressure control unit and the rotation speed detected by the pulley rotation speed detecting means as parameters.

16. The speed change control device as defined in claim 13, wherein one of the two or more parameters is the speed ratio of the continuously variable transmission, and the driving speed limiting means limits the driving speed to an increasingly lower speed as the speed ratio shifts toward a low side.

17. The speed change control device as defined in claim 13, wherein one of the two or more parameters is the rotation speed detected by the pulley rotation speed detecting means, and the driving speed limiting means limits the driving speed to an increasingly lower speed as the detected rotation speed decreases.

18. The speed change control device as defined in claim 13, further comprising an engine as the drive source, wherein the driving speed limiting means prohibits limitation of the driving speed when a throttle opening of the engine is smaller than a predetermined low opening.