Fuel pump
A pump for a fuel delivery system comprises a main housing and a plunger housing arranged to couple to the main housing so as to define a compression chamber therebetween. The main housing and the plunger housing comprise respective first and second opposed faces which are arranged to form a seal therebetween. The main housing comprises a projecting portion which projects from the first face of the main housing through an opening in the second face of the plunger housing into a plunger bore.
1. A pump for a fuel delivery system, the pump comprising:
a main housing and a plunger housing arranged to couple to the main housing so as to define a compression chamber therebetween,
the main housing and the plunger housing comprising respective first and second opposed faces which are arranged to form a seal therebetween;
wherein the main housing comprises a projecting portion which projects from the first face of the main housing through an opening in the second face of the plunger housing into a plunger bore, and the projecting portion is sized so as to be a clearance fit with an adjacent wall of the plunger bore;
the main housing comprising an inlet valve for controlling a flow of fuel into the compression chamber, the inlet valve comprising a valve member arranged for reciprocating movement within a valve bore defined by the main housing, wherein the valve bore is formed, at least in part, in the projecting portion.
2. A pump according to claim 1 , wherein the projecting portion comprises a valve seat disposed at a distal end thereof, the valve member comprising a valve head arranged to close against the valve seat when the inlet valve is in a closed state.
3. A pump according to claim 2 , wherein the valve head projects away from the valve seat into the compression chamber.
4. A pump according to claim 3 , comprising a plunger arranged for reciprocating movement within the plunger bore, wherein an end of the plunger proximal to the second face of the plunger housing comprises a recess therein, and wherein, in use, at least a portion of the valve head is received within the recess of the plunger during a pumping stroke of the plunger.
5. A pump according to claim 1 , comprising a plunger arranged for reciprocating movement within the plunger bore.
6. A pump according to claim 5 , wherein the plunger has a substantially cylindrical form and comprises a close clearance annular portion disposed toward an end of the plunger proximal to the second face of the plunger housing, wherein the close clearance annular portion serves to limit or substantially prevent fuel from leaking out of the compression chamber, in use.
7. A pump according to claim 6 , wherein the end of the plunger proximal to the second face of the plunger housing comprises a recess therein.
8. A pump according to claim 7 , wherein the close clearance annular portion of the plunger is disposed between said end of the plunger and a base of the recess.
9. A pump according to claim 1 , wherein the projecting portion is a substantially cylindrical boss.
10. A pump according to claim 9 , wherein the valve bore is co-axial with the substantially cylindrical boss.
11. A pump according to claim 1 , wherein at least one of the first and second face comprises an annular seal which encircles the projecting portion.
12. A pump according to claim 11 , wherein the annular seal is provided on the main housing and has a cross section which tapers towards contact with the plunger housing.
13. A pump according to claim 12 , wherein the annular seal defines a relatively narrow annular contact surface at its extremity which contacts the plunger housing.
14. A pump according to claim 1 , wherein the main housing and the plunger housing are coupled to one another by threaded fastening means.
15. A fuel delivery system comprising a pump according to claim 1 .