High pressure pump and engine system using the same

A method of controlling the delivery of pressurized fluid from a variable delivery, sleeve-metered pump, said pump having a plurality of pumping pistons and associated metering sleeves, said method comprising:

• reciprocating said pistons to thereby deliver pressurized fluid to a high pressure area of said pump at a pressure at least equal to a first pressure;
• delivering a portion of the pressurized fluid to a control circuit operable to selectively control the relative position between said pistons and their associated metering sleeves;
• reducing the pressure of the fluid delivered to said control circuit to a pressure less than said first pressure;
• and
• using said reduced-pressure fluid to control the relative position between said pistons and their associated metering sleeves, thereby controlling the delivery of pressurized fluid from said pump.

A control circuit for a sleeve-metered pump, said sleeve-metered pump having a plurality of pumping pistons and associated metering sleeves, comprising:

• a pressure reducing valve having an inlet in fluid communication with a high pressure area of said sleeve-metered pump and having a valve outlet, said pressure reducing valve reducing the pressure of control fluid entering said control circuit to a predetermined control circuit pressure;
• a movable control member having a first control surface and a second control surface opposed with said first control surface, movement of said control member changing the relative positioning between said pumping pistons and their associated sleeves;
• a control line in fluid communication with said pressure reducing valve outlet and having a first, relatively unrestricted passageway through which fluid pressure is applied to said first control surface and a second, relatively-restricted passageway through which fluid pressure is applied to said second control surface;
• an electrically operated control valve fluidly connected with said control line to selectively control the relative fluid pressures applied to said first and second control surfaces.

A control circuit for a sleeve-metered pump, said sleeve-metered pump having a plurality of pumping pistons and associated metering sleeves, comprising:

• a pressure reducing valve having an inlet in fluid communication with a high pressure areas of said sleeve-metered pump and having a valve outlet, said pressure reducing valve reducing the pressure of control fluid entering said valve to a predetermined control circuit pressure;
• a movable control member having a control surface, movement of said control member changing the relative positioning between said pumping pistons and their associated sleeves;
• a control line in fluid communication with said pressure reducing valve outlet and having a restricted passageway through which fluid pressure is applied to said control surface;
• a bias member applying a force to the control member in a direction opposite the fluid pressure applied to said control surface;
• and
• an electrically operated control valve connected with said control line to selectively control the fluid pressure applied to said control surface.