Control device and control method of belt type continuously variable transmission for vehicle

Abstract

A vehicle belt-type continuously variable transmission expands the operating range in which belt slip control is permitted with maintained estimated accuracy of a belt slip condition, to reduce drive energy consumption owing to a reduction in belt friction. It includes a primary pulley (42) and a secondary pulley (43) around which a belt (44) is wound to generate a belt clamping force according to an input torque from an engine (1) by controlling a secondary hydraulic pressure, a belt slip control means ( Fig. 8 ) for controlling the secondary hydraulic pressure according to a phase difference (¸) between oscillation components due to oscillation included in an actual gear ratio and in an actual secondary hydraulic pressure, and an input torque change speed limiting means (step S23 in Fig. 12 ) for determining whether or not to limit vehicle acceleration according to a predetermined acceleration limit permitting condition (steps S21, S22, S26) and limiting the change speed of the input torque to less than a predetermined value when determining to limit the vehicle acceleration.

Description

technical field [0001] The present invention relates to a control device and a control method of a belt-type continuously variable transmission for a vehicle, which perform belt slip control in which a belt wound around a pulley slips at a predetermined slip rate. Background technique [0002] Conventionally, as a control device for a belt-type continuously variable transmission for a vehicle, there is known a device (for example, refer to Patent Document 1) that makes the actual secondary oil pressure lower than the normal control and uses When the belt that is wound around the pulley is slipping at a specified slip rate, the belt slip is controlled. [0003] (a) Superimpose a predetermined sine wave on the secondary oil pressure, that is, excite the secondary oil pressure to make it vibrate, [0004] (b) The belt slip control is performed by controlling the secondary hydraulic pressure based on the product of the excited vibration component contained in the actual seconda...

AI Technical Summary

Problems solved by technology

[0007] However, in the conventional control device of the belt-type continuously variable transmission for vehicles, there is a problem that when the input torque to the belt-type continuously variable transmission mechanism changes rapidly, the change of the secondary oil pressure accompanying the change The speed also becomes faster, and in the actual secondary oil pressure characteristics, it is impossible to clearly extract the excitation-realized vibration components contained in the actual secondary oil pressure from the basic components of the actual secondary oil pressure based on the magnitude of the input torque.

Therefore, when the change speed of the input torque is fast and the vibration component realized by the excitation contained in the actual secondary oil pressure cannot be extracted, when the vibration component realized by the excitation contained in the actual gear ratio and the vibration component contained in the actual secondary oil pressure In belt slip control where the product value of the vibration component achieved by the excitation is an estimated value representing the belt slip state and the value is converged to a specified value, the control accuracy may not be ensured due to the estimation error of the belt slip state. The belt slips greatly in the belt slip control according to the magnitude of the input torque to the belt type continuously variable transmission

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