Poclain Hydraulics Industrie

Claude Didierjean

Gery Depierre

Pierre-Louis Houillon

A method for controlling a vehicle including a main transmission and a hydraulic transmission, in which, in the absence of a setpoint on the brake, and when the hydraulic transmission is activated, a hydraulic pump of the hydraulic transmission is controlled in such a way as to establish a predetermined pressure inside a hydraulic circuit of the hydraulic transmission, and in the event of a setpoint applied to the brake, the hydraulic transmission is then controlled according to an acceleration setpoint applied to the vehicle. If the acceleration setpoint is greater than or equal to an acceleration threshold value, and the speed of travel of the vehicle is less than or equal to a speed threshold value, the hydraulic transmission is controlled in such a way as to apply a tractive force. If the acceleration setpoint is less than the first threshold value, the hydraulic transmission is disengaged.

Control method for hydraulic assistance

A method for controlling a transmission device of a vehicle. The device includes a hydraulic transmission. The displacement of the hydraulic pump is controlled so that it delivers to the n hydraulic motors a constant flow that is proportional to the speed of the wheels rotated by the drive. The displacement control of the hydraulic pump is carried out by a correction constant and a correction variable. The correction variable is determined in real time. The correction constant includes the sum of a theoretical constant and an adjusted constant. The theoretical constant is defined according to the theoretical behaviour of the hydraulic transmission. The adjusted constant is defined and corrected when the vehicle is in predetermined conditions of use, in order to reflect the real state of the vehicle.

Method for controlling the displacement of a pump for a hydraulic assistance

According to the method, transmission apparatus of a vehicle, the apparatus comprising a drive engine (), a mechanical transmission () connected to the drive engine, and a hydraulic transmission () having a pump () and n hydraulic motors (A,B), where n is greater than or equal to 1, the pump being suitable for being driven by the drive engine for feeding fluid to the hydraulic motors. The method consists in performing a 'low-speed' assistance stage, during which, when the vehicle is driven by the mechanical transmission, the method consists in establishing a setpoint pressure for the pressure difference between the feed and the discharge of each of the hydraulic motors, in feeding the hydraulic motors by the pump, in detecting the pressure difference between the feed and the discharge (A,B) of each of the hydraulic motors (A,B), and in adjusting the delivery rate of the pump so that said pressure difference is substantially equal to said setpoint pressure.

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Verberie, France

Claude Didierjean