Sauer Gmbh

Sauer-danfoss Inc.

Sauer-dafoss Inc.

Wilhelm Gollner

Eric R Jacobson

Manfred Maiers

Hydraulic system with a hydraulic machine, in particular an axial piston or radial piston unit, with rotating and moving machine components which are arranged in a housing. The housing is connected to a high-pressure and a low-pressure line of a working circuit, which is supplied with pressure fluid by means of a charge pump. The leakage fluid which occurs in the housing collects in a leakage fluid reservoir which is arranged below the rotating and moving hydraulic machine components in the working position of the hydraulic machine and is connected fluidically to the housing. The leakage fluid is pumped out of the leakage fluid reservoir into the low-pressure line of the working circuit by the charge pump.

Hydraulic system with leakage fluid removal

The invention relates to a hydrostatic transmission having two bent axis- or swashplate-type axial piston units which are operated alternately as a pump and as a motor, with the two axial piston units being adjustable together with a pivotable dual yoke or by means of a pivotable dual swashplate. In order to minimize the dead volumes of the two axial piston units, the rotational axes of the two axial piston power units are offset with respect to the pivot axis of the dual yoke or of the swashplate by a magnitude such that, at all pivot angles, the power unit pistons, at dead center, are located in the direct vicinity of the bore end of the cylinder block.

Hydrostatic transmission having two axial piston units

A radial piston pump having external loading. The radial piston pump has an inner eccentric which is attached to a rotatable driveshaft, a cylinder block which has positionally fixed cylinder bores aligned radially with respect to the driveshaft, and displacement pistons which are mounted in a longitudinally movable manner in the cylinder bores. The displacement pistons have a piston head with a short casing height, and are mounted with their piston base on the eccentric, in such a way that the piston head, during its longitudinal movement, pivots in a predetermined angle range (&#x394;&#x3b1;) about the longitudinal central axis of the associated cylinder bore.

Radial piston pump

A power split transmission concept for two or three or four modes is provided with two variable hydrostatic units, an engine mechanically connected to the rowsun of a planetary gear set with at least two planetary rows, the second row of the planetary rows being connected to a rowsun, whereby both hydrostatic units stay connected with the same planetary element through all modes, one hydrostatic unit being connected to the sun of rowand the other hydrostatic unit being connected to a ring gear of planetary row

Transmission concept for dual yoke hydrostatic units

A control device apparatus for a proportionally adjustable hydraulic pump of a closed hydraulic circuit, including an axial piston pump adjustable from a zero position in two pivoting directions, with an electro hydraulic valve configuration for the activation of a piston of the hydraulic pump from both sides and with a feedback device, connected to the piston and whereby the angular pivoting position of the piston can be fed back to the valve configuration as a control signal, the valve configuration having a valve for each pivoting direction of the piston, and the feedback device comprising two mechanical feeler elements, each connected to one of the valves and in sliding engagement with the piston in such a way that the feeler elements are actuated when it leaves the zero position.

Control device for a proportionally adjustable hydraulic pump and a variable displacement pump for a hydrostatic drive

A control device for variable hydraulic machines, and specifically for variable axial piston machines equipped with a servo system that is connected to a swash plate so that the discharge/displacement volume is infinitely variable. The hydraulic machine is equipped with a sensor that detects the piston displacement and is connected with an electronical control unit that controls the swash angle position of the swash plate and is pressure controlling the servo system by an electrohydraulic converter. A method for the infinite controlling of the volume flow of hydraulic machines, by which the servo system is connected to the swash plate of the hydraulic machine, and by which a conduction of a signal from a sensor to the control unit, a pressure controlling of the servo system by an electrohydraulic converter as well as the controlling of the swash angle position of the swash plate by the electronical control unit is realized.

Control device for variable hydraulic machines

A control system for a hydrostatically driven vehicle comprises a hydraulic drive system having a hydraulic drive unit. An electronic control unit on the machine being driven is operatively connected to the hydraulic drive unit and is adapted to transmit and receive electronically data with respect to the drive unit. An external operator control unit is comprised of a data card inserted into a manual control means and is detachably connected to the electronic control unit. The data carrier card has an interface capable of transmitting data into and receiving data from the hydraulic drive unit to the electronic control unit. The data carrier card and the external operator control unit have memory capability.

Hydrostatic drive with data carrier control

A method for putting into operation a vehicle with an electronically controlled automotive hydrostatic transmission, wherein an output current of an electronic control by means of at least one proportional pressure-reducing valve is used for generating a control pressure acting upon the servo system of the variable displacement pump. The method is performed by the following steps: a) determining a limit value of a driving regime of the vehicle; b) detecting, digitizing and reading-in at least one current operational parameter of the transmission into the electronic control; c) determining and detecting at least one characteristic value of the output current of the electronic control corresponding to the value of the driving regime of the transmission to the one proportional pressure-reducing valve, and d) calculating a current characteristic on the basis of the value of the output current for achieving reproducible driving properties.

Method to calibrate a hydrostatic transmission with electronic controls

An automotive control driving mechanism for a vehicle, such as a wheel loader or fork lift, comprising a plurality of wheels (18) supporting a vehicle frame, an engine (16) on the frame for driving the wheels (18), and a hydrostatic transmission having a variable displacement pump (12) operatively connected to the engine (16) and to at least one motor (14). The motor (14) is connected to at least one of the wheels (18) to propel the vehicle. The transmission generates a working system pressure in a pair of fluid conduits (32,34) between its pump (12) and motor (14). A microprocessor (40) is connected to a speed pickup (38) on the engine shaft (39) and conduits (32,34) of the hydrostatic transmission for controlling the displacement of the pump through swashplate (20), and thus the transmission ratio, based not only on the engine speed but also system pressure. The sensed system pressures values are embedded into microprocessor's (40) control algorithms for the transmission ratio. The transmission may also include variable displacement motors controlled in the same manner. When electronically proportional high pressure relief valves are associated with said conduits, improved braking and coasting are realized.

Driving mechanism for an automotive propel drive

A displacement control valve has a valve body with a fluid metering valve spool axially movable between pilot pressure chambers formed at opposite ends of an interior bore in the valve body. An internal spring feedback apparatus is mounted on the valve spool in one of the pilot pressure chambers and elastically interconnects the swashplate of a variable displacement hydraulic unit with the valve spool. An elongated housing surrounds the spring and spring guides and is mechanically coupled with the swashplate. The housing and spring guides form a fluid seal between the valve spool and the valve body to seal the pilot pressure chamber in which the feedback apparatus is mounted.

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Neumunster, Germany

Wilhelm Gollner