Continuously-variable transmission for vehicle

Abstract

Disclosed is a continuously-variable transmission for a vehicle, which can realize the enlargement of speed-ratio width and preferable energy saving performance. the continuously-variable transmission for a vehicle includes a belt-type continuously-variable transmitting mechanism (3) connected to a drive source (ENG) and configured to continuously vary a speed ratio of the belt-type continuously-variable transmitting mechanism (3); an auxiliary transmitting mechanism (4) provided in series with the belt-type continuously-variable transmitting mechanism (3) and configured to attain a plurality of shift steps for a forward running of the vehicle; and a speed-increasing gear mechanism (2) provided upstream from the auxiliary transmitting mechanism (4) and configured to increase an input rotational speed of the auxiliary transmitting mechanism (4).

Description

technical field [0001] The present invention relates to a continuously variable transmission for a vehicle, which is applied as a transmission of a vehicle and includes a belt type continuously variable transmission mechanism and an auxiliary transmission mechanism in series. Background technique [0002] At present, as a continuously variable transmission for a vehicle, there is known a continuously variable transmission as follows, that is, a continuously variable transmission is configured to provide a two-stage forward sub-transmission mechanism in line with a belt-type continuously variable transmission mechanism, and according to the operation of the vehicle The gear ratio range that can be obtained without increasing the size of the belt-type continuously variable transmission mechanism by changing the gear stage of the auxiliary transmission mechanism (for example, refer to Patent Document 1). [0003] In a continuously variable transmission for a vehicle having such...

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Problems solved by technology

[0006] However, in a continuously variable transmission for a vehicle equipped with a belt-type continuously variable transmission mechanism and an auxiliary transmission mechanism in series, during the shift transition period in the auxiliary transmission mechanism, when the input rotational speed does not change but only the output shaft torque changes, it is called In the "torque phase" phase generated at the beginning of the shift, the output shaft torque decreases due to the replacement of the coupled friction element and the released friction element

[0007] On the other hand, the coordinated shift that maintains the through gear ratio at a certain level is effective in suppressing the shift shock in the phase called the "inertia phase" of the input speed change during the shift transition period in the auxiliary transmission mechanism, but cannot The effect of suppressing the shift shock in the "torque phase" where the input rotational speed is not expected to change

[0008] Therefore, when shifting in the auxiliary transmission mechanism, there is a problem that a shift shock called "traction shock" occurs due to a decrease in the output torque in the "torque phase", which greatly damages the shift quality.

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