Ball check-valve for linear reciprocating downhole pumps

A sucker-rod pump comprising:

• (a) a barrel comprising an interior cavity with a surface, the barrel configured to house a plunger, a valve rod, and at least one ball check-valve assembly;
• (b) the valve rod mechanically connected to an upper end of the plunger and configured to drive the plunger up and down the sucker-rod pump;
• (c) a hold-down assembly attached to a bottom of the barrel and configured to maintain position of the sucker-rod pump components as the plunger is driven up and down;
• and
• (d) the at least one ball check-valve assembly comprising:
• (i) a ball;
• (ii) a casing comprising an outer surface and defining an internal cavity extending within the casing, the internal cavity comprising a cylindrical inner wall;
• (iii) a bottom threaded connection at a downhole end of the casing, the bottom threaded connection comprising an opening therethrough to allow fluid passage into the internal cavity;
• (iv) a top threaded connection at an uphole end of the casing, the top threaded connection comprising an opening therethrough to allow fluid passage from the internal cavity and upwardly through the downhole sucker rod pump;
• (v) at least three longitudinally extending guides defined within internal cavity, the at least three longitudinally extending guides defined as longitudinal ridges extending inwards from the cylindrical inner wall and defining a ball-race whereby the ball has freedom of motion coaxially within the internal cavity, the ball-race allowing movement of the ball to the top of the ball-race during a downstroke and allowing movement of the ball to the bottom of the ball-race during an upstroke;
• and
• (vi) a sealing surface formed in the casing and interposed between the top threaded connection and the internal cavity, the sealing surface formed as a concave wall facing the internal cavity and generally closing an area between the internal cavity and the top threaded connection, the sealing surface further defining at least three quartic-shaped flow-passages extending from the sealing surface and providing for fluid passage through the sealing surface from the internal cavity to the uphole end of the casing, the sealing surface further comprising concavity matching a diameter of the ball whereby the at least three quartic-shaped flow-passages are substantially closed by the ball during the downstroke.