Jatco Corporation

Seonjae Kim

Tetsuya Izumi

Hironori Nihei

Toshiji Iida

Fumito Shinohara

Takayuki Tanaka

Toshiyuki Shibuya

Kwang-ho Lee

Kiyotaka Sawano

Naohiro Hoshi

Takeshi Chibahara

Takuya Numata

Toru Koga

In a speed ratio control device for a belt continuously variable transmission according to this invention, when a speed ratio is subjected to feedback control on the basis of a difference between an actual speed ratio and a target speed ratio, pressure supplied to a primary pulley is corrected through feedforward (S, S) in order to suppress variation in the groove width of the primary pulley caused by a rapid variation in an input torque into the primary pulley (S) while traveling in a fixed speed ratio mode (S) in which the target speed ratio is held at a fixed value.

Speed ratio control device and method for belt type continuously variable transmission

In a line pressure control device for a belt type continuously variable transmission according to this invention, when a line pressure is feedback-controlled to equal a target line pressure which is equal to or greater than the larger of oil pressures supplied to a primary pulley and a secondary pulley (S), and it is determined that the target line pressure has fallen below a first low pressure, leading to a divergence between the target line pressure and the actual line pressure (S), the target line pressure is restricted such that the target line pressure does not fall below a lower limit value (S).

Line pressure control device and method for belt type continuously variable transmission

A positional deviation ERRstep of a step motoris calculated on the basis of a reference model step StepMdl, an actual speed ratio-corresponding step Bstep, and an added value obtained by adding together a target deviation GTstep, calculated in accordance with a transmission input torque Ti, and a starting learned value Gstep. When the transmission input torque Ti is large, the target deviation GTstep is increased in accordance with the transmission input torque Ti. A line pressure PL is then controlled on the basis of the positional deviation ERRstep obtained as a result.

Continuously variable transmission and control method thereof

When a line pressure PL serving as a source pressure of a primary pulley () and a secondary pulley () is controlled on the basis of a control deviation &#x394;Step, which is the deviation between a step count StepMdl of a step motor () corresponding to a target speed ratio I (o) and a value obtained by adding a target deviation GTstep and a starting learned value Gstep to a step count Bstep of the step motor () corresponding to an actual speed ratio ip, the engine torque varies dramatically beyond the range of a predetermined value Tand a predetermined value Tduring a predetermined time period t, a learning error determination relating to the starting learned value Gstep is prohibited for a predetermined time period t

In a line pressure control apparatus of a belt-drive CVT, a shift is achieved by varying V- groove widths of primary and secondary pulleys by a differential pressure between primary and secondary pulley pressures, originating from line pressure. The differential pressure is created by bringing a shift actuator, such as a step motor, into a control position corresponding to a target transmission ratio. The target transmission ratio is calculated based on a theoretical transmission ratio based on engine-and-vehicle operating conditions, taking account of a hardware response delay and a disturbance. The target transmission ratio is converted into a reference-model operative position, corresponding to a reference-model number-of-steps of the shift actuator. An actual transmission ratio is converted into an actual-transmission-ratio related operative position. Line pressure is corrected in a manner so as to reduce the positional deviation between the reference-model operative position and the actual-transmission-ratio related operative position.

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Seoul, South Korea

Seonjae Kim