Fuel pump and inlet valve assembly thereof

An inlet valve assembly for a fuel pump having a fuel pump housing with a pumping chamber defined therein;

• a pumping plunger which reciprocates within a plunger bore along a plunger bore axis such that an intake stroke of said pumping plunger increases volume of said pumping chamber and a compression stroke of said pumping plunger decreases volume of said pumping chamber, said inlet valve assembly comprising:
• a valve body having 1) a valve body bore which is centered about, and extends along, a valve body bore axis, 2) a valve body inlet passage which opens into said valve body bore, and 3) a valve body outlet passage which opens into said valve body bore;
• a check valve with a check valve member which moves between a seated position and an unseated position, wherein said seated position prevents flow through said valve body outlet passage in a direction into said valve body bore and said unseated position permits flow through said valve body outlet passage such that said valve body bore is in fluid communication with said pumping chamber;
• and
• a valve spool within said valve body bore, said valve spool being moveable along said valve body bore axis between 1) a first position in which said valve spool maintains said check valve member in said unseated position and in which said valve body inlet passage is in fluid communication with said valve body outlet passage and 2) a second position in which said check valve member is able to move to said seated position and in which said valve body inlet passage is not in fluid communication with said check valve member.

An inlet valve assembly for a fuel pump having a fuel pump housing with a pumping chamber defined therein;

• a pumping plunger which reciprocates within a plunger bore along a plunger bore axis such that an intake stroke of said pumping plunger increases volume of said pumping chamber and a compression stroke of said pumping plunger decreases volume of said pumping chamber, said inlet valve assembly comprising:
• a valve body having 1) a valve body bore which is centered about, and extends along, a valve body bore axis, 2) a valve body inlet passage which opens into said valve body bore, and 3) a valve body outlet passage which opens into said valve body bore;
• a check valve with a check valve member which moves between a seated position and an unseated position, wherein said seated position prevents flow through said valve body outlet passage in a direction into said valve body bore and said unseated position permits flow through said valve body outlet passage such that said valve body bore is in fluid communication with said pumping chamber;
• and
• a valve spool within said valve body bore, said valve spool being moveable along said valve body bore axis between 1) a first position in which said valve spool maintains said check valve member in said unseated position and in which said valve body inlet passage is in fluid communication with said valve body outlet passage and 2) a second position in which said check valve member is able to move to said seated position and in which said valve body inlet passage is not in fluid communication with said valve body outlet passage;
• wherein:
• said valve body inlet passage is a valve body first inlet passage;
• said valve body also includes a valve body second inlet passage which opens into said valve body bore;
• said first position prevents flow into and out of said valve body bore through said valve body second inlet passage;
• said valve spool is also moveable to a third position in which said check valve member is able to move to said seated position and in which flow is permitted through said valve body second inlet passage into said valve body bore;
• and
• said valve spool is also moveable to a fourth position in which said check valve member is able to move to said seated position and in which said valve body second inlet passage is in in fluid communication with said valve body outlet passage with less restriction through said valve body second inlet passage than said third position.