Digital controlled fluid translating device

#The subject invention generally relates to a variable displacement fluid translating device and more particularly to a digitally controlled variable displacement fluid translating device that is capable of controlling flow in both directions.

#Variable displacement fluid translating devices are well known in the art and may be in the form of a fluid pump or a fluid motor. The displacement of these known types have typically been controlled by changing the angle of a cam plate, changing an eccentric of a rotating cam or by changing the timing of the inlet and outlet ports therein. The displacement of many of these known pump/motors are capable of operation in an overcenter position. That is, the flow direction with in the pump/motor is changed by the displacement mechanism being moved both directions from a zero displacement position. It is also known to change the displacement of a pump/motor by causing the flow from selected ones of the internal pistons to be bypassed across a solenoid controlled poppet valve to the low pressure side thereof. An example of such a variable displacement pump/motor is set forth in U.S. Pat. No. 5,259,738 issued on Nov. 9, 1993 to the University of Edinburgh. However, the pump/motor arrangement of U.S. Pat. No. 5,259,738 is only capable of operation in a two quadrant mode. It would be beneficial to have a fluid translating device in which the displacement thereof could be changed by controlling the fluid in and out of each individual piston therein and also be operational in a four quadrant mode.

#The subject invention is directed to overcoming one or more of the problems as set forth above.

#FIG. 1 is a schematic representation of a work system utilizing the subject invention;

#FIG. 2 is a schematic representation of another work system utilizing the subject invention;

#FIG. 3 is a diagrammatic representation of an embodiment of the subject invention;

#Referring to FIG. 1, a work system 10 is illustrated. The work system 10 of FIG. 1 includes a power source 14 drivingly connected to a variable displacement fluid translating device 12. A second fluid translating device 12′, in the form of a fluid motor, is drivingly connected to a load or work element 18 and is fluidily connected to the first variable displacement fluid translating device 12 by conduits 20,21.

#The variable displacement fluid translating device 12 could be a fluid pump or a fluid motor and will be described in more detail hereinafter. Likewise the variable displacement fluid translating device 12 could be a radial, wobble plate, axial or bent axis design. The work system 10 of the subject embodiment could be, for example, a hydrostatic drive arrangement.

#Speed and position sensors 22,22′ are associated with the variable displacement fluid translating device 12 and are operative to detect the respective speeds of the variable displacement fluid translating devices 12,12′ and the rotational position of its internal mechanism. It is recognized that the speed and position sensor 22,22′ could be disposed within the respective variable displacement fluid translating device 1212′. The detected speeds and positions are delivered to a controller 24. The controller 24 is also operatively connected by respective wiring harnesses 25,25′ to the variable displacement fluid translating devices 12,12′.