Mannesmann Rexroth Corporation

Zahnradfabrik Friedrichshafen, Ag.

Zf Friedrichshafen Ag

Sauer Getriebe Kg

Heinrich W Nikolaus

Robert Paton

Frank Metzner

Peter Reinhardt

Rolf Kordak

Abdul Arain

Gerhard Ditter

Rainer Bavendiek

Continuously variable transmission

Arrangement and process for operating a fail safe braking system in a

A digital electronic control apparatus for controlling at least one electronic control element comprises. The apparatus comprises first and second pulse width modulated output signal generators, the frequency of the second signal being different from the first. The second pulse width modulated signal is provided as a function of a digital value determined by at least one of a characteristic and operating condition of the at least one electronic control element. An AND-gate receives the first and second pulse width modulated signals and is capable of producing an output signal for controlling the at least one electronic control element a first and second pulse width modulated signal having a first frequency.

Digital control electronic having a pulse width modulated (PWM)-output

The invention relates to a variable displacement pump supplying fluid to a number of consumers. The pump control for adjusting the delivery rate is actuated by a signal which is produced by the respective highest loaded consumer. The signal is provided by a valve, in particular a pressure compensating valve which is associated with the consumer, and which valve opens a spool land when the valve becomes positioned at its control end range. A pressure signal from any pressure fluid source is delivered through the land to the pump controller. The control, according to the invention, offers a broad variety of possibilities for arranging the pressure compensation valve at various locations, engaging the valve by a variety of pressure differences, and using a number of pressure fluid sources of provide for the signal pressure to actuate the pump controller.

Variable displacement pump with hydraulic adjustment for controlling the

A control circuit includes a microprocessor, a table store and an amplifier stage to control a controlled device which has a non-linear or linear, but discontinuous response curve. To obtain a linear response curve of the controlled device the table store is loaded with a response curve map in operating the controlled device. Thereafter the data loaded in pairs in the table store are inversely read-out and used as a control signal for the controlled device. The table store thus allows to linearize the response curve of the controlled device. In addition the data may be modified. According to the invention any correcting means to obtain an ideal response of the controlled device is eliminated. The invention provides for an optimum performance, smallest possible expenditure of circuitry and shortest possible control time.

Control circuit for an electrically controlled servo device

The invention refers to a hydraulic system comprising at least a variable displacement pump and at least a consumer. Means are provided to generate electrical limit signals when at least one of the consumers, preferrably a load leading consumer indicates the need for an increased delivery rate or when the variable displacement pump indicates a hydraulic under-supply. In response to the limit signals generated by the consumer need or the pump are varied in a control circuit to adjust the control signals delivered to the servo devices of the hydraulic systems such that the pump control is optimized and that the flow rates to the consumers are decreased in the mode of under-supply. In addition very simple electrical circuits are disclosed to substantially reduce the expenditure of the system.

Circuitry for controlling control coils of servo devices in a hydraulic

Continuously variable driving unit of a motor vehicle

Arrangement and method for operating a continuously variable drive unit

An automatic control including a memory is provided to be loaded with positional data for the automatic control of a cycle of motions of preferably a plurality of power members. The speed reading the data in and out is freely selectable. Accordingly programming a cycle of motions may be performed in a slow motion process, whereas the speed of reading out the data is selected such that an optimum operational speed is obtained. In addition to the automatic speed control a manual control is provided to interrupt the cycle motion of the automatic control to manually adjust the position or the power member. In returning to the automatic control the further cycle of motion is taken up again where it has been interrupted.

Automatic control system

Arrangement and method for operating a variable drive unit

A cylinder unit is supplied with pressurized fluid from a hydraulic machine which is variable in speed and/or displacement. The machine may be operated as a pump and as a motor to increase the pressure or, respectively, to decrease the pressure so that the piston of the cylinder unit may be actuated in both directions and, furthermore, the brake energy is recovered by the machine when the piston is driven through an external load. This results in an increased efficiency of the control apparatus for the cylinder unit avoiding any problems arising from heat.

Control apparatus for double acting hydraulic cylinder units

The torque of a hydraulic machine is dependent of the fluid pressure delivered to the machine and is further dependent of the adjustment of its volume of through-put. In response to a load coupled to the machine, a speed results which is controlled by a speed control system acting on the adjusting system of the hydraulic machine. According to the invention, an electro hydraulic speed control comprises a pair of control circuits which are connected to, but operate independent of each other. Thus the electrical control circuit produces a control signal y.sub.e1 from the difference of the actual value and the desired value of the speed for adjusting a hydraulic restricting means which produces a hydraulic pressure signal p.sub.st in the hydraulic control circuit which pressure signal is compared with a hydraulic reference signal p.sub.o to produce a differential pressure signal p.sub.o -p.sub.st which is applied to the adjusting cylinder of the hydraulic machine. The control system thus comprises two circuits, i.e. an electrical speed control circuit and a hydraulic pressure control circuit resulting in optimizing the control operation.

Hydraulic drive system

A hydraulic transmission, in particular for an automotive drive system including a combustion engine comprises at least a pair of hydrostatic pumps and at least a pair of hydrostatic motors each pump and/or motor having the same size or different size with a constant or adjustable through-put. Automatically actuated clutches are provided to connect the pumps to the engine and to connect the motors to a load. A variety of transmission ranges is obtained by activating selected ones of the individual pumps and motors by actuating corresponding clutches. Therefore, the combustion engine may be operated under conditions in which fuel comsumption is as low as possible.

Hydraulic transmission

A secondarily controlled hydrostatic machine with variable volume is connected to a line with impressed system pressure which is fed by a primary unit. By switching over the primary unit the secondary unit is subjected to a displacement amount which results in as large as possible a pivot angle of the secondary unit to obtain the highest possible efficiency. The switching over takes place in dependence upon an upper and lower switching point corresponding to the desired pivot angle range of the secondary unit.

Control means for a drive system with impressed pressure

A hydrostatic machine, in particular of bent axis design comprises a clutch which is provided between the drive shaft and the pistons. The force necessary for clutch engagement is produced by hydraulic pressure forces which are either applied to the pistons or delivered by the pistons depending on whether the machine operates as a motor or as a pump. When the machine neither produces a moment nor receives a moment the clutch is automatically disengaged due to the reduction of the hydraulic pressure forces. According to the invention the clutch helps to prevent hydraulic losses of the machine while running idle and improves the overall efficiency.

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Hamburg, Germany

Heinrich W Nikolaus