초록 ▼

An infinitely variable differential hydrostatic transmission utilizing a fixed displacement pump/motor and a variable displacement pump/motor interconnected with appropriate valving, to provide a mechanical/hydraulic differential drive which is capable of achieving an overall efficiency in the 98°-9

An infinitely variable differential hydrostatic transmission utilizing a fixed displacement pump/motor and a variable displacement pump/motor interconnected with appropriate valving, to provide a mechanical/hydraulic differential drive which is capable of achieving an overall efficiency in the 98°-99°range. In the preferred embodiment, which utilizes axial piston type pump motors, pistons in multiples of four are utilized in order that each piston will have a piston located 90°from it to serve as its control valve. The fixed and variable displacement motor/pump are provided as an integral unit containing bearing mountings, cylinder barrels, valve ports, piston seal mountings, hydraulic flow passages, pressure reservoirs and manifolding by forming a series of individual segments and sealing them together into a single structural unit. A unique mounting arrangement is utilized to positively attach the pistons to an anti-friction swashplate which eliminates all side loads on the piston. Finally, a novel piston valve seal reduces hydraulic leakage and sliding friction, and a novel pumping device is utilized for pressurizing the pump motor units and replacing fluid lost through leakage.

대표청구항 ▼

A differential hydrostatic transmission, comprising: an outer case; an input shaft and an output shaft rotatably disposed in said case; a first unit having a plurality of first pistons respectively slidably disposed in a plurality of first piston chambers therein, said first unit being fixedly attac

A differential hydrostatic transmission, comprising: an outer case; an input shaft and an output shaft rotatably disposed in said case; a first unit having a plurality of first pistons respectively slidably disposed in a plurality of first piston chambers therein, said first unit being fixedly attached to said input shaft so as to rotate therewith; a second unit having a plurality of second pistons respectively slidably disposed in a plurality of second piston chambers therein, said second unit being fixedly attached to said input shaft so as to rotate therewith; a first swashplate means connected to said first pistons and to said output shaft for converting oscillatory motion of said first pistons to rotational movement of said output shaft and vice versa, said first swashplate means being disposed at an angle with respect to the longitudinal axis of said first pistons; a second swashplate means connected to said second pistons for converting rotational movement of said second unit into oscillatory motion of said first pistons and vice versa, said second swashplate being angularly adjustable from a first position to a second position and being rotatably fixed to said outer case; means for communicating said second piston chambers with said first piston chambers and vice versa such that fluid pumped from said first piston chambers flows into said second piston chambers and fluid from said second piston chambers flow into said first piston chambers wherein the output speed and output torque of said output shaft is controlled by adjusting the angular position of said second swashplate means between said first position and said second position so as to correspondingly adjust the fluid displacement of said second unit with respect to said first unit; means for controlling the angle of said second swashplate means to provide an infinite range of output shaft speeds and torques; wherein said first swashplate means comprises: an alignment collar fixedly attached to said output shaft so as to be rotatable therewith; an outer swashplate ring to which each of said first pistons are attached, said outer swashplate ring having pivot attaching means for connecting said first pistons to said outer swashplate ring in such a manner as to allow said outer swashplate ring to freely pivot in a sinusoidal manner with respect to said first pistons when said first pistons are oscillating; antifriction bearing means for allowing said outer swashplate ring to rotate with respect to said alignment collar; wherein said outer swashplate ring includes a plurality of spherical cavities disposed therein for respectively receiving an end of said first pistons and wherein said pivot attaching means comprises: a plurality of pairs of semispherical segments respectively disposed in said cavities in such a manner that the planar surfaces thereof oppose one another, one of said segments in each of said pairs having a through-hole; a plurality of end fittings respectively secured to the end of each of said first pistons, each of said fittings having an axial portion and a flat portion, said axial portion extending through said through-hole of said one segment, said flat portion being disposed between said opposing planar surfaces of said pair of segments; and antifriction sliding means disposed between said flat surface of each of said end fittings and said planar surface of the other of said segments in each of said pair of segments such that when said outer swashplate ring is disposed at an angle with respect to said first pistons, any forces exerted by said outer swashplate ring are aligned along the longitudinal axis of said first pistons.