Device and method for controlling a belt-type continuously variable transmission for a vehicle

Abstract

Disclosed is a continuously variable transmission that expands the operating range over which belt-slip control is allowed, while maintaining the estimated precision of the belt-slip state. This reduces belt friction, thereby reducing the drive energy used. A belt (44) is wrapped around a primary pulley (42) and a secondary pulley (43), and the gear ratio is controlled by controlling a primary hydraulic pressure and a secondary hydraulic pressure. The disclosed belt-type continuously variable transmission for a vehicle is provided with a belt-slip control means (fig. 8) and a gear-ratio change-rate limitation means (step S23 in fig. 12). When a gear-ratio change rate is less than a given value, said gear-ratio change rate being the rate at which the gear ratio changes, the belt-slip control means controls the secondary hydraulic pressure on the basis of a phase difference ( ) between a vibration component due to oscillation in the actual gear ratio and a vibration component due to oscillation in the actual secondary hydraulic pressure. The gear-ratio change-rate limitation means uses prescribed acceleration limitation allowance conditions to determine whether or not the acceleration of the vehicle may be limited (steps S21, S22, and S26 in fig. 12), and if so, limits the gear-ratio change rate to less than the aforementioned given value.

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...

AI Technical Summary

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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