Force balanced valve spool

Claim 1

A flow control valve comprising: a valve body defining a main bore and a cross bore extending into, through, and beyond the main bore; a valve spool reciprocable along a line of motion within the main bore and defining first and second lands connected by a connecting portion which defines groove means between the first and second lands; the valve spool being movable along said line of motion to a first position wherein the first and second lands are on either side of the cross bore and in blocking relation with the valve body within the main bore; and to a second position wherein the first land is moved into the cross bore to allow fluid flow between the cross bore and main bore, the second land moving with the first land away from the cross bore; and means comprising an annular rib fixed to the connecting portion substantially midway between the first and second lands and extending adjacent to the valve body within the main bore, said rib being generally alined with a side of the cross bore in said second position and cooperating with said first land for guiding fluid flow through the groove means in a direction substantially perpendicular to the line of motion of the valve spool while substantially blocking off fluid flow from the area of the second land, whereby the second land is substantially shielded from the impact of fluid flowing between the cross bore and main bore.