Fuel pump with inlet valve assembly

1. A fuel pump comprising:

a fuel pump housing with a pumping chamber defined therein and an inlet valve bore extending along an inlet valve bore axis to an exterior of said fuel pump housing;

a pumping plunger which reciprocates within a plunger bore such that an intake stroke of said pumping plunger increases a volume of said pumping chamber and a compression stroke of said pumping plunger decreases the volume of said pumping chamber; and

an inlet valve assembly which 1) selectively provides fluid communication between an inlet of said fuel pump and said pumping chamber and 2) selectively prevents fluid communication between said inlet of said fuel pump and said pumping chamber, said inlet valve assembly comprising:

an inner housing which is received within said inlet valve bore such that said inner housing extends to the exterior of said fuel pump housing and such that an outer periphery of said inner housing is sealed to an inner periphery of said inlet valve bore such that fuel is prevented from passing radially between said inner housing and said inlet valve bore to the exterior of said fuel pump housing;

an outer housing which is located outside of said fuel pump housing and circumferentially surrounds said inner housing, wherein an annular chamber is defined radially between said inner housing and said outer housing and axially between said outer housing and said fuel pump housing; and

a sealing ring which is made of an elastomer material and which is annular in shape and located within said annular chamber such that said sealing ring is compressed axially against said fuel pump housing and said outer housing;

wherein said sealing ring is not exposed to fuel from within said fuel pump.

2. A fuel pump as in claim 1 , wherein said inlet valve assembly includes a solenoid assembly, said solenoid assembly comprising:

said inner housing;

said outer housing;

a pole piece made of a magnetically permeable material located within said inner housing;

a coil of electrically conductive wire which circumferentially surrounds said pole piece and such that said coil is located radially between said inner housing and said outer housing, wherein electricity is applied to coil causes a magnetic attraction between said pole piece and a valve element of said inlet valve assembly such that said valve element moves toward said pole piece.

3. A fuel pump as in claim 2 , wherein:

said outer housing includes a flange which is annular in shape and which extends inward toward said inner housing such that said flange provides a path for magnetic flux to pass when electricity is applied to said coil; and

said sealing ring is compressed axially against said flange.

4. A fuel pump as in claim 2 , wherein:

said solenoid assembly further comprises an overmold which is made of an electrically insulative material and which fills between said coil and said outer housing, said overmold including a central aperture;

said inner housing extends into said central aperture such that an annular gap is located radially between said inner housing and said central aperture;

said sealing ring is a first sealing ring; and

said solenoid assembly further comprises a second sealing ring which is made of an elastomer material and which is annular in shape and located within said annular gap such that said second sealing ring is radially compressed against said inner housing and said overmold.

5. A fuel pump as in claim 2 , wherein

said solenoid assembly further comprises an overmold which is made of an electrically insulative material and which fills between said coil and said outer housing, said overmold including a central aperture;

said inner housing extends into said central aperture such that an annular gap is located radially between said inner housing and said central aperture;

said solenoid assembly further comprises sealing cap which closes off said central aperture.

6. A fuel pump as in claim 5 , wherein said sealing cap is not exposed to fuel from within said fuel pump.

7. A fuel pump as in claim 4 , wherein said second sealing ring is not exposed to fuel from within said fuel pump.

8. A fuel pump comprising:

a fuel pump housing with a pumping chamber defined therein and an inlet valve bore extending along an inlet valve bore axis to an exterior of said fuel pump housing;

a pumping plunger which reciprocates within a plunger bore such that an intake stroke of said pumping plunger increases a volume of said pumping chamber and a compression stroke of said pumping plunger decreases the volume of said pumping chamber; and

an inlet valve assembly which 1) selectively provides fluid communication between an inlet of said fuel pump and said pumping chamber and 2) selectively prevents fluid communication between said inlet of said fuel pump and said pumping chamber, said inlet valve assembly comprising:

an inner housing which is received within said inlet valve bore such that said inner housing extends to the exterior of said fuel pump housing and such that an outer periphery of said inner housing is sealed to an inner periphery of said inlet valve bore such that fuel is prevented from passing radially between said inner housing and said inlet valve bore to the exterior of said fuel pump housing;

an outer housing which is located outside of said fuel pump housing and circumferentially surrounds said inner housing, wherein an annular chamber is defined radially between said inner housing and said outer housing and axially between said outer housing and said fuel pump housing; and

a first sealing ring which is made of an elastomer material and which is annular in shape and located within said annular chamber such that said first sealing ring is compressed axially against said fuel pump housing and said outer housing;

wherein said inlet valve assembly includes a solenoid assembly, said solenoid assembly comprising:

said inner housing;

said outer housing;

a pole piece made of a magnetically permeable material located within said inner housing; and

a coil of electrically conductive wire which circumferentially surrounds said pole piece and such that said coil is located radially between said inner housing and said outer housing, wherein electricity is applied to coil causes a magnetic attraction between said pole piece and a valve element of said inlet valve assembly such that said valve element moves toward said pole piece;

wherein said solenoid assembly further comprises an overmold which is made of an electrically insulative material and which fills between said coil and said outer housing, said overmold including a central aperture;

wherein said inner housing extends into said central aperture such that an annular gap is located radially between said inner housing and said central aperture;

wherein said solenoid assembly further comprises a second sealing ring which is made of an elastomer material and which is annular in shape and located within said annular gap such that said second sealing ring is radially compressed against said inner housing and said overmold; and

wherein said second sealing ring is not exposed to fuel from within said fuel pump.

9. A fuel pump as in claim 8 , wherein said first sealing ring is not exposed to fuel from within said fuel pump.

10. A fuel pump comprising:

a fuel pump housing with a pumping chamber defined therein and an inlet valve bore extending along an inlet valve bore axis to an exterior of said fuel pump housing;

a pumping plunger which reciprocates within a plunger bore such that an intake stroke of said pumping plunger increases a volume of said pumping chamber and a compression stroke of said pumping plunger decreases the volume of said pumping chamber; and

an inlet valve assembly which 1) selectively provides fluid communication between an inlet of said fuel pump and said pumping chamber and 2) selectively prevents fluid communication between said inlet of said fuel pump and said pumping chamber, said inlet valve assembly comprising:

an inner housing which is received within said inlet valve bore such that said inner housing extends to the exterior of said fuel pump housing and such that an outer periphery of said inner housing is sealed to an inner periphery of said inlet valve bore such that fuel is prevented from passing radially between said inner housing and said inlet valve bore to the exterior of said fuel pump housing;

an outer housing which is located outside of said fuel pump housing and circumferentially surrounds said inner housing, wherein an annular chamber is defined radially between said inner housing and said outer housing and axially between said outer housing and said fuel pump housing; and

a sealing ring which is made of an elastomer material and which is annular in shape and located within said annular chamber such that said sealing ring is compressed axially against said fuel pump housing and said outer housing;

wherein said inlet valve assembly includes a solenoid assembly, said solenoid assembly comprising:

said inner housing;

said outer housing;

a pole piece made of a magnetically permeable material located within said inner housing; and

a coil of electrically conductive wire which circumferentially surrounds said pole piece and such that said coil is located radially between said inner housing and said outer housing, wherein electricity is applied to coil causes a magnetic attraction between said pole piece and a valve element of said inlet valve assembly such that said valve element moves toward said pole piece;

wherein said solenoid assembly further comprises an overmold which is made of an electrically insulative material and which fills between said coil and said outer housing, said overmold including a central aperture;

wherein said inner housing extends into said central aperture such that an annular gap is located radially between said inner housing and said central aperture;

wherein said solenoid assembly further comprises sealing cap which closes off said central aperture; and

wherein said sealing cap comprises:

a sidewall which is located within said central aperture in an interference fit; and

an end wall which extends radially outward from said sidewall which abuts said overmold and limits how far said sealing cap is inserted into said central aperture.