Motor driven pump

A motor driven pump comprising

• a rigid post member,
• an impeller housing carried by said post member on one side thereof and having a fluid inlet connection and a fluid delivery connection communicating with the interior thereof,
• a motor housing carried by said post member on the other side thereof, and having a motor stator therein,
• said post member having a motor stator isolating sleeve extending therefrom and into said motor housing interiorly of said motor stator,
• said sleeve having an end closure remote from said post member,
• a hollow mandrel carried at one end in said impeller housing and at the other end in said end closure,
• a rotary impeller shaft journalled on said mandrel and movable axially thereon,
• an impeller in said impeller housing secured to said shaft and a motor rotor in said motor housing and in spaced relation to said sleeve,
• said motor rotor being in spaced relation to said sleeve to provide a fixed orifice with an inlet in communication with said impeller housing at the outlet of the impeller and with an outlet in communication with a pressure chamber between said motor rotor and said end closure,
• said mandrel being in communication at one end with the inlet of said impeller and at the other end having port means communicating with said pressure chamber,
• said motor rotor being longitudinally axially movable for varying the size of said port means and the discharge of fluid and control of pressure in said pressure chamber.