Patent ID: 8464756

Claim:
A spool valve comprising: a housing defining a bore extending along a longitudinal axis, a supply port in fluid communication with said bore and configured for supplying a hydraulic fluid to said bore, a first load port in fluid communication with said bore and configured for directing the hydraulic fluid along a first flow path, a second load port in fluid communication with said bore and configured for directing the hydraulic fluid along a second flow path, and at least one exhaust port in fluid communication with said bore and configured for exhausting the hydraulic fluid from said housing; and a spool disposed within said bore and moveable between at least a first position and a second position, wherein said first position opens fluid communication between said supply port and said first load port, opens fluid communication between said second load port and said at least one exhaust port, and closes fluid communication between said supply port and said second load port, and wherein said second position opens fluid communication between said supply port and said second load port, opens fluid communication between said first load port and said at least one exhaust port, and closes fluid communication between said supply port and said first load port; said spool having a first land portion and a second land portion, and including a supply portion disposed axially along said longitudinal axis between the first land portion and the second land portion, said supply portion defining a truncated pseudosphere configured for directing the hydraulic fluid to said first load port when said spool is in said first position and directing the hydraulic fluid to said second load port when said spool is in said second position; wherein the truncated pseudosphere includes a ridge disposed at a midsection of the supply portion; wherein the truncated pseudosphere includes a first half and a second half disposed on opposite sides of the ridge; wherein the supply portion includes a first curve portion disposed between the first half of the truncated pseudosphere and the first land portion, the first curve portion defining a diameter continuously decreasing in size along the longitudinal axis from the first land portion to the first half of the truncated pseudosphere, wherein the first curve portion cooperates with the first half of the truncated pseudosphere to direct the hydraulic fluid from the supply port to the first load port when the spool is in the first position; and wherein the supply portion includes a second curve portion disposed between the second half of the truncated pseudosphere and the second land portion, the second curve portion defining a diameter continuously decreasing in size along the longitudinal axis from the second land portion to the second half of the truncated pseudosphere, wherein the second curve portion cooperates with the second half of the truncated pseudosphere to direct the hydraulic fluid from the supply port to the second load port when the spool is in the second position.