Direct drive rotary valve

A rotary valve for metering fluid flow, the rotary valve comprising:

• a bushing including an axially extending cylindrical bore defining an inner wall of the bushing;
• and
• a cylindrical spool received by the cylindrical bore for rotation relative to the bushing about a central axis;
• the bushing and the spool being configured to provide a first fluid supply path, a second fluid supply path, a first fluid return path, and a second fluid return path;
• the bushing and the spool including respective edges defining a first supply edge pair (P-C1), wherein the respective edges of the first supply edge pair are angularly displaceable relative to one another to open and close the first fluid supply path;
• the bushing and the spool further including respective edges defining a second supply edge pair (P-C2), wherein the respective edges of the second supply edge pair are angularly displaceable relative to one another to open and close the second fluid supply path;
• the bushing and the spool further including respective edges defining a first return edge pair (C2-R1), wherein the respective edges of the first return edge pair are angularly displaceable relative to one another to open and close the first fluid return path;
• and
• the bushing and the spool further including respective edges defining a second return edge pair (C1-R2), wherein the respective edges of the second return edge pair are angularly displaceable relative to one another to open and close the second fluid return path;
• wherein the first supply edge pair (P-C1) is angularly spaced from the first return edge pair (C2-R1) by a first angle greater than or equal to 120 degrees and less than 180 degrees, and the second supply edge pair (P-C2) is angularly spaced from the second return edge pair (C1-R2) by a second angle greater than or equal to 120 degrees and less than 180 degrees.

A rotary valve for metering fluid flow from a source of pressurized fluid with respect to a first chamber and a second chamber in a fluid-powered load, the rotary valve comprising:

• a bushing including an axially extending cylindrical bore defining an inner wall of the bushing;
• and
• a cylindrical spool received by the cylindrical bore for rotation relative to the bushing about a central axis;
• wherein the bushing further includes a fluid source passageway adapted for communication with the source of pressurized fluid, a first metering conduit adapted for flow communication with the first chamber of the fluid-powered load, and a second metering conduit adapted for flow communication with the second chamber of the fluid-powered load;
• wherein the bushing further includes a first return duct open through the inner wall and a second return duct open through the inner wall;
• wherein the spool includes a first metering channel extending transversely through the spool, a second metering channel extending transversely through the spool, a first return passage, and a second return passage;
• wherein the spool has a null rotational position wherein the fluid source passageway is not in flow communication with either of the first and second metering channels, a first metering rotational position wherein the fluid source passageway is in flow communication with the first metering channel but not the second metering channel while the second metering channel is in flow communication with the first return passage by way of the first return duct, and a second metering position wherein the fluid source passageway is in flow communication with the second metering channel but not the first metering channel while the first metering channel is in flow communication with the second return passage by way of the second return duct.