A transmission includes a gearing arrangement configured to shift speed ratios by disengaging an off-going shift element and engaging an oncoming shift element and an electrohydraulic valve having an actuatable valve element configured to control an engagement state of the oncoming shift element. A controller is programmed to, during a shift of the transmission, in response to the off-going shift element disengaging and an expected ratio change not initiating, monotonically increase current to the valve to a maximum value to overcome frictional resistance on the valve element, and programmed to, in response to expiration of a timer and the ratio change still not initiating, send a repeating pattern of high and low current signals according to a duty cycle to overcome frictional resistance of the valve element.

Desired is a control device for a vehicle drive apparatus capable of determining an engagement failure in an engagement device when shifting a transmission device to a neutral state and making the rotational speed of a driving force source reduced. In order to shift a transmission device from a state in which an object shift speed is established and the vehicle is traveling to a neutral state in which no shift speed is established in the transmission device (#02), when an object engagement device is disengaged while maintaining engagement of a non-object engagement device and the rotational speed of a driving force source (#04, #06) is made to be reduced, an engagement failure in the object engagement device (#02, #07) is determined based on a change in the rotational speed of an input member.

A transmission includes a gearing arrangement configured to shift speed ratios by disengaging an off-going shift element and engaging an oncoming shift element and an electrohydraulic valve having an actuatable valve element configured to control an engagement state of the oncoming shift element. A controller is programmed to, during a shift of the transmission, in response to the off-going shift element disengaging and an expected ratio change not initiating, monotonically increase current to the valve to a maximum value to overcome frictional resistance on the valve element, and programmed to, in response to expiration of a timer and the ratio change still not initiating, send a repeating pattern of high and low current signals according to a duty cycle to overcome frictional resistance of the valve element.

A hydraulic control device that includes a primary pressure control valve that has a first valve element and that regulates the primary pressure by varying a position of the first valve element in accordance with operation of a first electromagnetic actuator; a secondary pressure control valve that has a second valve element and that regulates the secondary pressure by varying a position of the second valve element in accordance with operation of a second electromagnetic actuator; and a fail-safe valve that varies the position of the first valve element such that the primary pressure is reduced when the first electromagnetic actuator and the second electromagnetic actuator become inoperable.

A transmission hydraulic control system includes a manual valve, a default valve, and a clutch prime valve. The manual valve allows fluid flow from a pressurized line to a drive line when the manual valve is open (when a transmission is in drive or reverse). The manual valve prevents fluid flow from the pressurized line to the drive line when the manual valve is closed (when the transmission is in neutral or park). The clutch prime valve allows fluid to flow from the pressurized line to the drive line, and thereby bypass the manual valve, when the manual valve is closed and the clutch prime valve is open. The default valve allows fluid bypassing the manual valve to flow to prime a clutch of the transmission when the default valve is open. The clutch prime valve prevents fluid from bypassing the manual valve when the clutch prime valve is closed.

A hydraulic control apparatus including a first and second control valves switched to exert hydraulic pressure on a piston to press toward first position, a third and fourth control valves switched to exert hydraulic pressure on the piston to press toward second position and, a CPU. The CPU performs executing a first process controlling the control valves so that hydraulic pressure is exerted by switching of the first, second and third control valves or a second process controlling the control valves so that hydraulic pressure is exerted by switching of the second control valve and determining that the first control valve is failed when movement of the piston to the first position is not detected through the first process and determining that the third control valve is failed when movement of the piston to the first position is not detected through the second process.

This invention provides two methods for detecting mechanical or electrical faults in a solenoid valve. In the first method, a force sensor is placed in the valve in such a way as to detect changes in the impact force of the plunger against the solenoid valve body or coil housing (depending upon the direction of movement of the plunger upon application of the electric current/magnetic field). A second method is provided which makes use of an accelerometer placed in such a way as to detect changes in the response of the plunger to the application of the magnetic field.

Under an abnormal determination, when a transmission gear stage is switched, a torque limit value is changed from a value before switching of the transmission gear stage to a value after switching thereof in a period in which this transmission gear stage is switched.

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.

A device and method for operating a fluid-guiding device, including an electrically operated fluid pump, which delivers fluid from a fluid sump of the fluid-guiding device and supplies it to at least one fluid consumer. A fluid volume in the fluid sump as well as a current intensity of the electric current taken up by the fluid pump and modeled on the basis of the rotational speed of the fluid pump are ascertained, and a comparison value is determined from the modeled current intensity. A deficient fluid supply of the fluid-guiding device is inferred if the fluid volume is greater than a threshold value and a measured current intensity of the electric current taken up by the fluid pump is less than the comparison value.