Device and method for controlling a belt-type continuously variable transmission for a 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 control gear ratio by controlling primary and secondary hydraulic pressures, a belt slip control means ( Fig. 8 ) for controlling 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 a transmission 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 a transmission speed 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, a device is known (for example, refer to Patent Document 1) that makes the actual secondary oil pressure lower than 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) Based on the product of the excited vibration component included in the actual secondary oil pressure and the excited vibration component included in the actual gear ratio, the sec...

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Problems solved by technology

[0007] However, in the conventional control device for a belt-type continuously variable transmission for vehicles, when the rate of change of the transmission ratio, that is, the transmission speed, is fast, in the fluctuation characteristics of the actual transmission ratio, it is not possible to clearly define from one corresponding to the operating state to the other. From the basic components of the actual gear ratio, the vibration component of the excited vibration contained in the actual gear ratio is extracted

Therefore, when the shifting speed is fast and the vibration component of the excitation included in the actual gear ratio cannot be extracted, there is a problem that when the vibration component of the excitation included in the actual gear ratio and the actual secondary oil pressure When the product value of the vibration components included in the excitation is used as an estimated value representing the belt slipping state, and the value is converged to a specified value in the belt slipping control, the control accuracy may not be ensured due to the estimation error of the belt slipping state. And the belt slips greatly in the belt slip control due to the magnitude of the input torque to the belt type continuously variable transmission

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