Danfoss A/s

Soren N Sorensen

Svend Erik Thomsen

Erik Kyster

Hans Christian Petersen

Jens K Simonsen

The invention relates to a rotary slide valve subassembly for a hydrostatic steering unit. The slide valve subassembly includes two concentric sleeves having near one end a plurality of circumferentially distributed axially extending slots which, in the neutral position, create a short circuit between the supply and discharge sides. The slots subdivide the corresponding sleeve sections into stays extending from the main sleeve sections. A construction is provided to avoid jamming of the sleeves by joining the stays of each sleeve section with a closed ring member and undercutting the inside diameter of the stays of the inner sleeve section to cause weakening thereof relative to the stays of the outer sleeve section.

Rotary slide for a hydrostatic steering unit

The invention relates to a hydrostatic steering control unit of the type having valving for an open center neutral position which bypasses pressurized fluid from the pump to the tank when in neutral. During a turning operation with a steering wheel the open center valving is caused to close and the pressurized fluid is directed to one side or the other of a servomotor which is connected to wheels to be steered. The open center valving includes orifices in relatively rotatable elements which are aligned in the neutral position and closed to effect the turning operation. Open center valving can be the cause of noise and cavitation and such valving herein is provided with slot shaped orifices and flat generally wedge shaped throttle passages to minimize the noise and cavitation problems. The throttle passages are defined by curved bounding surfaces having rectangularly shaped outlines.

Hydraulic control apparatus

The invention relates to a hydrostatic steering control unit of the type having valving for an open center neutral position which bypasses pressurized fluid from the pump to the tank when in neutral. During a turning operation with a steering wheel the open center valving is caused to close and the pressurized fluid is directed to one side or the other of a servomotor which is connected to wheels to be steered. The open center valving includes orifices in relatively rotatable elements which are aligned in the neutral position and closed to effect the turning operation. Open center valving can be the cause of noise and cavitation and such valving herein is provided with slot shaped orifices and flat generally wedge shaped throttle passages to minimize the noise and cavitation problems. The throttle passages are defined by curved bounding surfaces having rectangularly shaped outlines. A characteristic of the curved surfaces is that they are formed with exponentially shaped sections.

Hydraulic control apparatus with an adjustable throttle

The invention relates to a fluid pressure operated motor or pump of the type having a gerotor displacement mechanism which normally includes inner and outer wheel and ring gears which in operation have relative rotational and orbital movement therebetween. Such devices inherently have a form of valving wherein, with a commutating type of action, fluid is directed from the casing inlet to expanding chambers of the gerotor and directed from collapsing gerotor chambers to the casing outlet. Two embodiments are presented in which the first has the casing thereof fixed in space. In both units the commutator valving includes valving patterns in two valve plates attached to opposite sides of the casing and in the wheel gear which has orbital movement relative to the casing. The commutating valving arrangement has control ports on opposite sides of the unit for feeding and exhausting motive fluid to and from the unit and auxiliary ports on opposite sides of the unit to balance or equalize the pressure forces on each side thereof. Bolts are used for fastening the tightening together the casing side plates. These bolts are also used as guides for the orbital path of the ring gear and holes are provided in the ring gear to accommodate the bolts.

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Nordborg, Denmark

Soren N Sorensen