An abnormality detection device for a hydraulic circuit including an oil pump, a switching unit switching between a fully discharged state and a partial discharge, a pressure regulator, a pressure regulation controller and a hydraulic detector, The device includes: a storage storing a maximum discharge pressure of oil capable of being discharged in the partially discharged state; a switching controller performing control of switching into the fully discharged state; and a determination unit determining that the switching unit has a fixation abnormality of the partially discharged state when a hydraulic pressure approximately corresponds to the maximum discharge pressure in the partially discharged state in a state where a hydraulic pressure higher than the maximum discharge pressure in the partially discharged state is set as a target hydraulic pressure and the pressure regulator is controlled to achieve the target hydraulic pressure after the switching control.

Hydraulic system and method for controlling pressure in a hydraulic system for a vehicle transmission with at least a primary friction element (2) and a secondary friction element (3) for coupling and transmitting engine power to the wheels of the vehicle by actuation of the friction elements (2) via the hydraulic system, comprising; supplying pressurized fluid to a line pressure circuit (7) by means of a pressure pump system having at least two outlet lines (5); providing a bypass circuit (9) on the pressure pump system that, when the bypass circuit (9) is open to allow flow therethrough; providing a bypass operating element (11) for controlling the bypass circuit (9) via a bypass valve (10); wherein the bypass operating element (11) additionally controls the secondary pressure on the secondary friction element (3) via a secondary valve (19); such that in a determined state; the bypass operating element (11) is actuated to open the bypass circuit (9) to reduce the flow to the line pressure circuit (7) and additionally to reduce the pressure on the secondary friction element (3) to a value lower than the pressure on the primary friction element (2), such that less torque is provided.

A method for controlling a continuously variable transmission is a control method of controlling in/out of oil to/from a primary oil chamber by using an oil pump provided in an oil passage between the primary oil chamber and a secondary oil chamber. The method includes: an abnormality determination step of determining whether rotation of the oil pump is abnormal; and when it is determined that the rotation is abnormal in the abnormality determination step, a hydraulic control step of making a secondary oil pressure higher than a pressure before the determination of abnormality.

A vehicle control device for controlling a vehicle including an oil pump driven by a transmission of a rotation of the motor-generator; and a hydraulic pressure supply unit for supplying a hydraulic pressure to the continuously variable transmission. The hydraulic pressure is generated by regulating a pressure of an oil discharged from the oil pump. When a regenerative braking is performed by the motor-generator based on a deceleration request from a driver, the hydraulic pressure supply unit supplies a hydraulic pressure based on a first hydraulic pressure and a second hydraulic pressure to the continuously variable transmission. The first hydraulic pressure is a hydraulic pressure to transmit an input torque input to the continuously variable transmission during the regenerative braking. The second hydraulic pressure is a hydraulic pressure to shift the continuously variable transmission during the regenerative braking. During the regenerative braking, the first hydraulic pressure is set to equal to or less than a hydraulic pressure found by subtracting the second hydraulic pressure from a hydraulic pressure suppliable to the continuously variable transmission.

A method for controlling a continuously variable transmission is a control method of controlling in/out of oil to/from a primary oil chamber by using an oil pump provided in an oil passage between the primary oil chamber and a secondary oil chamber. The method includes: an abnormality determination step of determining whether rotation of the oil pump is abnormal; and when it is determined that the rotation is abnormal in the abnormality determination step, a hydraulic control step of making a secondary oil pressure higher than a pressure before the determination of abnormality.

A continuously variable transmission has a primary pulley hydraulic chamber, a secondary pulley hydraulic chamber, a first oil passage connected to the secondary pulley hydraulic chamber, a second oil passage connected to the primary pulley hydraulic chamber, the second oil passage branching from the first oil passage, an electric oil pump provided on the second oil passage so as to allow oil to flow into and flow out from the primary pulley hydraulic chamber, and an oil discharge mechanism configured to discharge oil outside the second oil passage, the oil being to be supplied to the primary pulley hydraulic chamber by the electric oil pump.

An abnormality detection device for a hydraulic circuit including an oil pump, a switching unit switching between a fully discharged state and a partial discharge, a pressure regulator, a pressure regulation controller and a hydraulic detector, The device includes: a storage storing a maximum discharge pressure of oil capable of being discharged in the partially discharged state; a switching controller performing control of switching into the fully discharged state; and a determination unit determining that the switching unit has a fixation abnormality of the partially discharged state when a hydraulic pressure approximately corresponds to the maximum discharge pressure in the partially discharged state in a state where a hydraulic pressure higher than the maximum discharge pressure in the partially discharged state is set as a target hydraulic pressure and the pressure regulator is controlled in an effort to achieve the target hydraulic pressure after the switching control.

Control system for a Continuously Variable Transmission with two pairs of conical sheaves each with an adjustable running radius, the sheave of each pair being coupled to a hydraulic actuator and the inlet port of each actuator being connected with the hydraulic actuator setting means, fed from the outlet port of a hydraulic displacement pump, connected to a supply of hydraulic medium and coupled to an electric motor which is controlled by a controller which controls the speed of the electric motor with a first control signal which is generated as a function of the actual transmission ratio of the transmission on one hand and of the desired speed of change of this transmission ratio on the other hand, all this in such a way that the speed of this first motor increases with an increase of the transmission ratio of the transmission on one hand and an increase of the speed of change of the ratio on the other hand, while the outlet port of the displacement pump is connected to the inlet of an electronically controllable pressure relief valve of which the set point is determined by a second control signal as a function of the set transmission ratio on one hand and the value of the actual torque transmitted through the transmission on the other hand, in such a way that de value of the resulting hydraulic pressure increases as the transmission ratio increases on one hand, and as the torque transmitted through the transmission increases on the other hand.

A continuously variable transmission has a primary pulley hydraulic chamber, a secondary pulley hydraulic chamber, a first oil passage connected to the secondary pulley hydraulic chamber, a second oil passage connected to the primary pulley hydraulic chamber, the second oil passage branching from the first oil passage, an electric oil pump provided on the second oil passage so as to allow oil to flow into and flow out from the primary pulley hydraulic chamber, and an oil discharge mechanism configured to discharge oil outside the second oil passage, the oil being to be supplied to the primary pulley hydraulic chamber by the electric oil pump.

Greater one of a secondary pressure comparison reference value (Psec_b) and a primary pressure comparison reference value (Ppri_b) is set as a line pressure target value (Plin_tg). At a vehicle constant speed travel control, a value obtained by adding a first offset amount () to the secondary pressure target value (Psec_tg) is the secondary pressure comparison reference value (Psec_b) and a value obtained by adding a second offset amount () to the primary pressure target value (Ppri_tg) is the primary pressure comparison reference value (Ppri_b). By setting a line pressure in this manner, an occurrence of fluctuation of an engine speed at during executing the vehicle constant speed travel control is suppressed.