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 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 transmission includes a plurality of pneumatic actuators for gear shifting, wherein the pneumatic actuators are arranged to discharge compressed air via a common ventilation system including at least one ventilation opening arranged in a housing arrangement of the transmission. A method for controlling ventilation of the transmission includes determining that a predetermined flushing condition is fulfilled and, in response thereto, initiating a flushing action in which at least two of the pneumatic actuators are controlled to discharge compressed air simultaneously or substantially simultaneously to the common ventilation system so as to force air through the at least one ventilation opening.

An oil pressure control device controls a supply pressure of oil supplied to an oil pressure chamber of a friction element having a first engagement board and a second engagement board engaged with or disengaged from each other between a non-engagement state and a non-sliding engagement state via a sliding engagement state. The oil pressure control device includes: an electromagnetic valve that controls the supply pressure using a spool which reciprocates according to an energizing amount; and a control part that defines a first oscillatory wave part in which the energizing amount is controlled by making a first waveform with a first frequency to superimpose on a second waveform with a second frequency higher than the first frequency during a first period while the sliding engagement state and an instruction value of the supply pressure are kept constant.

A normal oil passage that supplies hydraulic pressure to a friction engagement element through a hydraulic control valve, and a bypass oil passage that supplies hydraulic pressure to the friction engagement element while bypassing the hydraulic control valve, are provided. By switching an operative position of a manual valve, a hydraulic pressure supply route to the friction engagement element is switched between the normal oil passage and the bypass oil passage. By switching to the bypass oil passage, the hydraulic pressure supplied to the friction engagement element is not affected by operation of the hydraulic control valve, and a cleaning control may be performed to cause the hydraulic control valve to perform a cleaning operation. Accordingly, even if an operation amount of the cleaning control for the hydraulic control valve is increased, malfunctions by the friction engagement element will not occur.

A method to control a road vehicle provided with a dual-clutch, servo-assisted transmission and standing still with the internal combustion engine turned on; the control method generally includes, when the road vehicle is standing still with the internal combustion engine turned on, the steps of: engaging a forward gear associated with a first clutch; engaging a reverse gear associated with a second clutch, which is different from and independent of the first clutch; closing the first clutch so as to cause the first clutch to transmit a first torque; and closing the second clutch so as to cause the second clutch to transmit a second torque, which is equal to the first torque multiplied by the quotient between a gear ratio of the reverse gear and a gear ratio of the forward gear.

A method to control a road vehicle provided with a dual-clutch, servo-assisted transmission and standing still with the internal combustion engine turned on; the control method comprises, when the road vehicle is standing still with the internal combustion engine turned on, the steps of: engaging a forward gear associated with a first clutch; engaging a reverse gear associated with a second clutch, which is different from and independent of the first clutch; closing the first clutch so as to cause the first clutch to transmit a first torque; and closing the second clutch so as to cause the second clutch to transmit a second torque, which is equal to the first torque multiplied by the quotient between a gear ratio of the reverse gear and a gear ratio of the forward gear.

An electromagnetic valve for a hydraulic system for an automatic transmission of a vehicle. An armature chamber is filled with hydraulic medium and fluidically connected to hydraulic lines of the hydraulic system. An armature is mounted in the armature chamber such that its stroke is adjustable. The armature includes a shut-off body and divides the armature chamber into an opening-side chamber facing the flow opening and into an inner chamber facing away from the flow opening. During a stroke of the armature, an oil exchange occurs, and a displacement volume of the hydraulic medium overflows from the opening-side chamber into the inner chamber. A hydraulic line leading to the opening-side chamber or to the inner chamber of the armature chamber includes a dirt collecting element that is designed as a permanent magnet and that retains contaminations in the hydraulic medium that flows through the hydraulic line during an oil exchange.

Pressure regulation valve control device has line pressure regulation valve (4) having line pressure solenoid (41) and line pressure spool valve (42) and CVT control unit (8) controlling secondary pressure (Psec) by actuating the line pressure spool valve (42) by solenoid pressure (Psol) produced by controlling current command value (I) to the line pressure solenoid (41). CVT control unit (8) has abnormality control unit (81). The abnormality control unit (81) is configured to, when decrease in secondary pressure (Psec) is detected during travel, execute, during travel, abnormality control that increases solenoid pressure (Psol), supplied to line pressure spool valve (42) from line pressure solenoid (41), more than solenoid pressure (Psol) of a time when the decrease in secondary pressure (Psec) is detected. With this, even when the decrease in the pressure is detected during travel, the decrease in the pressure is suppressed during travel while reducing influence on vehicle travel.

An electromagnet for a hydraulic system, such as an automatic transmission of a motor vehicle. The electromagnet may include an armature chamber filled with hydraulic medium, which may be fluidically connected to hydraulic lines of the hydraulic system, and may have an armature mounted therein. The armature may have an adjustable stroke and may include a shut-off body. The armature may divide the armature chamber into an opening-side chamber facing the flow opening, and an inner chamber facing away from it. During a stroke movement of the armature, an oil exchange may occur, during which a displacement volume of the hydraulic medium overflows from the opening-side chamber into the inner chamber. The electromagnet may further include a hydraulic medium reservoir, which may store a hydraulic medium having a higher degree of purity than the hydraulic medium in the hydraulic lines and which may be fluidically connected to the opening-side chamber.