An electro-hydraulic park control system includes a park piston and a park control valve disposed in a valve body of a transmission of a vehicle and configured to control a supply of hydraulic fluid pressure to control the park piston and to operate such that (i) no single element failure of the transmission will cause the transmission to shift from a park state to a non-park state or (ii) to shift from a drive, reverse, or neutral state to the park state, (iii) the transmission is able to remain in the non-park state and remain in or transition to the neutral state when a controller of the transmission is malfunctioning while the transmission is operating in the drive, reverse, and neutral states, and (iv) the transmission is able to quickly transition to the park state while an engine/motor driven pump of the transmission is off or not running.

A parking lock for a transmission of a motor vehicle having an interlocking element of a connecting rod that is biased against a parking lock disengagement direction to bring and keep a ratchet tooth of a locking pawl in engagement with a tooth space of a parking interlock gear during an engagement of the parking lock. The connecting rod is provided a spring force acting in a parking lock engagement direction from an inserting spring and a compressive force acting in the parking lock disengagement direction from a hydraulically actuatable actuator having first piston pressurizable to disengage the parking lock. A detent device actuatable by an electromagnet mechanically fixes the first piston in either a latched or unlatched piston position associated with an engaged or disengaged position of the parking lock, respectively. A system determines a current engagement position of the detent device by assessing an inductance at the electromagnet.

A method for actuating a parking lock of a motor vehicle including a piston (10) which is arranged to move axially within a cylinder (9) of a parking lock actuator (8) and is acted upon by pressure in order to disengage the parking lock. A nominal pressure target, for disengaging the parking lock, is continuously increased from a first pressure value (p.sub.start) until the parking lock is either disengaged or until a maximum pressure value (p.sub.max) is reached.

A vehicle park lock assembly includes a park valve that moves in a first direction to transition a lever from a first to a second position, and moves in an opposite, second direction to permit movement of the lever from the second to the first position. The assembly includes a support block that limits movement of the park valve in the first direction. The assembly includes a biasing device coupled to the support block and the park valve. The biasing device biases the park valve to the first position. A method of supporting components of a vehicle park lock assembly includes moving a park valve in a first direction to transition a lever from a first to a second position, and moving the park valve in an opposite, second direction to permit movement of the lever from the second to the first position. The method also includes biasing the park valve to the first position with a biasing device that is coupled to the lever and a support block, and limiting movement of the park valve in the first direction using the support block.

A method for controlling a motor vehicle having at least one park lock. A drive train of the motor vehicle has a drive motor, wheel, and a transmission. An operating element actuates the park lock, which can assume a blocking position, in which the park lock blocks the drive train and/or a part of the drive train, and a release position. After actuation of the operating element, the park lock is switched from the release position into the blocking position (or vice versa). Here, the speed of the motor vehicle is determined. After actuation of the operating element and if the park lock assumes the release position beforehand, it is checked whether the speed is greater than a predefined first threshold value. If this check was successful, a first warning signal is produced; and the switching of the park lock into the blocking position is performed.

A method for reducing torsional shock of a driving system of an electric vehicle is provided. In the method, torsional torque of a part of the driving system is calculated by applying motor torque to a motor under the condition that a parking gear is engaged and monitoring a motor speed. Reverse torsional torque having the same magnitude as the calculated torsional torque is applied to the part of the driving system when release of the parking gear is requested, and then the parking gear is released to reduce shock caused by torsion of the part of the driving system when the parking gear is released.

A vehicle park lock assembly includes a park valve that moves in a first direction to transition a lever from a first to a second position, and moves in an opposite, second direction to permit movement of the lever from the second to the first position. The assembly includes a support block that limits movement of the park valve in the first direction. The assembly includes a biasing device coupled to the support block and the park valve. The biasing device biases the park valve to the first position. A method of supporting components of a vehicle park lock assembly includes moving a park valve in a first direction to transition a lever from a first to a second position, and moving the park valve in an opposite, second direction to permit movement of the lever from the second to the first position. The method also includes biasing the park valve to the first position with a biasing device that is coupled to the lever and a support block, and limiting movement of the park valve in the first direction using the support block.

A hydraulically controlled park system disengages a parking pawl in response to engagement of particular shift elements. When the vehicle is one a grade, greater force may be required to dis-engage the pawl, potentially leading to a failure to dis-engage. The controller avoids this failure by engaging an uphill gear ratio and controlling the transmission input torque to transfer load from the parking pawl to the gearing prior to engaging the shift elements that dis-engage the pawl. Following dis-engagement of the parking pawl, the transmission is in a tie-up condition in which the output shaft is held stationary by shift elements. The controller transitions from this tie-up condition to the selected gear ratio by releasing shift elements.

The invention relates to a hydraulic system for a vehicle transmission, comprising: a hydraulic circuit arranged for generating a pressure, a hydraulic actuator arranged for engaging a park lock system, wherein the hydraulic actuator is hydraulically connected to the hydraulic circuit for actuation of the hydraulic actuator using the pressure, and a back-up system configured to keep the pressure above a predetermined pressure threshold for maintaining an actuation of the hydraulic actuator for a predetermined period of time in case of an operational interruption of a transmission control unit of the vehicle.

A method for operating a parking lock device with a hydraulic system, the method including applying the pressure between the parking lock valve and the pressure chamber at the parking lock valve against the actuating force. Moreover, when there is a demand to disengage the parking lock device, the method includes applying the pilot pressure at the parking lock valve against the actuating force when the pressure between the parking lock valve and the pressure chamber of the parking lock valve is less than a threshold value at which the parking lock valve is transferred into a further operating condition range. Additionally, when there is a demand to disengage the parking lock device, the method includes adjusting the pilot pressure applied at the positioning valve to a pressure level at which the positioning valve is transferred into or held in its defined operating condition range.