High-flow direct-drive rotary servovalve

In a rotary valve adapted to be associated with a fluid source and a fluid return, and adapted to control the flows of fluid through variable-area metering ports with respect to the opposed chambers of a fluid-powered load, said valve having a body provided with an elongated bore, said body having a passageway communicating at a location along said bore, said valve also having an elongated spool member rotatably mounted in said bore, said spool member having a passage adapted to cooperate with said body passageway so as to selectively uncover a metering port therebetween, the orifice area of said metering port being a function of the angular position of said spool member relative to said body, and wherein the direction of fluid flow is inward from said one passageway to said spool member passage, the improvement which comprises:

• said body passageway being so configured and arranged so as to cause the inward flow through said metering port to be substantially radial such that the application of tangential reaction forces attributable to said inward flow to said spool member is substantially eliminated, and wherein a wall of the passageway located upstream of said orifice terminates in an edge of said metering port which is arranged in a plane containing the axis of said spool and said wall is relieved from said plane by an angle of at least 21.degree. such that the flow through said metering port is substantially radial.

In a rotary valve adapted to be associated with a fluid source and a fluid return, and adapted to control the flows of fluid through variable-area metering ports with respect to the opposed chambers of a fluid-powered load, said valve having a body provided with an elongated bore, said body having two passageways communicating with said bore at spaced locations therealong, said valve also having an elongated spool member rotatably mounted in said bore, said spool member having two passages each adapted to cooperate with a respective one of said body passageway so as to selectively uncover two metering ports therebetween, the orifice areas of said metering ports being a function of the angular position of said spool member relative to said body, and wherein the direction of fluid flow is inward through one metering port and outward through the other metering port, the improvement which comprises:

• said body passageways and said spool passages being so configured and arranged that the application of tangential reaction forces attributable to the flows through each of said metering ports to said spool member is substantially eliminated, and wherein a wall of each passageway or passage located upstream of an associated orifice terminates in an edge of said metering port which is arranged in a plane containing the axis of said spool and said wall is relieved from said plan by an angle of at least 21.degree. such that the flow through said metering port is substantially radial.