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A thermal load control assembly for a fuel injector includes a rail inlet port, a cooling inlet port and a fuel drain port. A leakage path channels leaked fuel originating from the rail inlet port to the fuel drain port. A cooling path channels fuel originating from the cooling inlet port to the fue

A thermal load control assembly for a fuel injector includes a rail inlet port, a cooling inlet port and a fuel drain port. A leakage path channels leaked fuel originating from the rail inlet port to the fuel drain port. A cooling path channels fuel originating from the cooling inlet port to the fuel drain port. A fuel system using a thermal load control assembly includes a single fuel tank that supplies fuel to the rail inlet port and the cooling inlet port of a plurality of fuel injectors and collect fuel from the fuel drain port of the plurality of fuel injectors.

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What is claimed is: 1. A common rail fuel injector, comprising: an injector body defining a nozzle outlet, a common rail inlet shaped and positioned for connection to a high pressure common rail, a cooling inlet port and a fuel drain port; a leakage path fluidly connecting the common rail inlet por

What is claimed is: 1. A common rail fuel injector, comprising: an injector body defining a nozzle outlet, a common rail inlet shaped and positioned for connection to a high pressure common rail, a cooling inlet port and a fuel drain port; a leakage path fluidly connecting the common rail inlet port to the fuel drain port; and a cooling path fluidly connecting the cooling inlet port to the fuel drain port=and wherein the cooling path remains open when the common rail fuel injector is in an injection configuration and/or a non-injection configuration; further including a control valve which further includes a valve member slidably disposed within a valve guide; and the leakage path includes a guide clearance defined between an outer surface of the valve member and an inner surface of the valve guide; and an electrical actuator operably coupled to move the valve member between a first position in contact with a seat, and a second position out of contact with the seat. 2. The fuel injector of claim 1, wherein the injector body includes an injector body casing and further including: a control valve having an external surface enclosed within the injector body casing; the cooling path includes a heat exchange interface with the external surface of the control valve; and an electrical actuator operably coupled to the control valve. 3. The fuel injector of claim 1, wherein the control valve includes: a weep annulus positioned on the valve guide; and a weep annulus passage defined within the control valve; and wherein the leakage path includes a heat exchange interface between the weep annulus with the control valve and the weep annulus passage with the control valve. 4. The fuel injector of claim 1 including an armature cavity disposed within an injector body casing, and further including: a cooling clearance defined between an internal surface of the casing and the external surface of the control valve; the cooling path includes the armature cavity and the cooling clearance; and an armature of the electrical actuator being attached to move with the valve member within the armature cavity. 5. The fuel injector of claim 4 further includes a direct controlled nozzle valve movable between a first position that closes the nozzle outlet and a second position that opens the nozzle outlet; the direct controlled nozzle valve includes an opening hydraulic surface exposed to fluid pressure in a nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in a needle control chamber; and the needle control chamber being fluidly connected to the common rail inlet port when in the non-injection configuration and fluidly connected to fuel drain passage by a valve supply passage. 6. A common rail fuel injector for a common rail fuel system in which fuel at high pressure is supplied to the fuel injector for injection into a combustion space, and low pressure fuel is circulated through the fuel injector for cooling the fuel injector due to heat transfer resulting from fuel leakage from an always high pressure area to an always low pressure area, the common rail fuel injector comprising: an injector body defining a nozzle outlet, a common rail inlet port, shaped and positioned for connection to a high pressure common rail, a cooling inlet port and a fuel drain port; a leakage path which includes a guide clearance between an outer surface of a valve member and a guide surface of valve body fluidly connecting the common rail inlet port to the fuel drain port; a cooling path fluidly connecting the cooling inlet port to the fuel drain port. 7. The common rail fuel injector of claim 6, wherein the injector body includes an injector body casing and further including: a control valve having an external surface enclosed within the injector body casing; the cooling path includes a heat exchange interface with the external surface of the control valve; and an electrical actuator operably coupled to the control valve. 8. The common rail fuel injector of claim 6 including a control valve which further includes a valve member slidably disposed within a valve guide; and the leakage path includes a guide clearance defined between an outer surface of the valve member and an inner surface of the valve guide; and an electrical actuator operably coupled to move the valve member between a first position in contact with a seat, and a second position out of contact with the seat. 9. The common rail fuel injector of claim 8, wherein the control valve includes: a weep annulus positioned on the valve guide; and a weep annulus passage defined within the control valve; and wherein the leakage path includes a heat exchange interface between the weep annulus with the control valve and the weep annulus passage with the control valve. 10. The common rail fuel injector of claim 8 including an armature cavity disposed within an injector body casing, and further including: a cooling clearance defined between an internal surface of the casing and the external surface of the control valve; the cooling path includes the armature cavity and the cooling clearance; and an armature of the electrical actuator being attached to move with the valve member within the armature cavity. 11. The common rail fuel injector of claim 10 further includes a direct controlled nozzle valve movable between a first position that closes the nozzle outlet and a second position that opens the nozzle outlet; the direct controlled nozzle valve includes an opening hydraulic surface exposed to fluid pressure in a nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in a needle control chamber; and the needle control chamber being fluidly connected to the common rail inlet port when in the non-injection configuration and fluidly connected to fuel drain passage by a valve supply passage. 12. A common rail fuel injector for a common rail fuel system in which fuel at high pressure is supplied to the fuel injector for injection into a combustion space, and low pressure fuel is circulated through the fuel injector for cooling the fuel injector due to heat transfer resulting from fuel leakage from an always high pressure area to an always low pressure area, the common rail fuel injector comprising: an injector body defining a nozzle outlet, a common rail inlet port shaped and positioned for connection to a high pressure common rail, a cooling inlet port and a fuel drain port; a leakage path which includes a guide clearance between a valve member and a valve body fluidly connecting the common rail inlet port to the fuel drain port, wherein fuel in the leakage path generates heat while dropping in pressure from a common rail pressure to a drain pressure; a cooling path fluidly connecting the cooling inlet port to the fuel drain port, wherein fuel passing through the cooling path absorbs heat generated by fuel in the leakage path; and the leakage path and the cooling path being sized and arranged so that fuel neither enters through the drain port nor exits through the cooling inlet port. 13. The common rail fuel injector of claim 12, wherein the injector body includes an injector body casing and further including: a control valve having an external surface enclosed within the injector body casing; the cooling path includes a heat exchange interface with the external surface of the control valve; and wherein the cooling path remains open when the common rail fuel injector is in an injection configuration and/or a non-injection configuration. 14. The common rail fuel injector of claim 12 including a control valve which further includes a valve member slidably disposed within a valve guide; and the leakage path includes a guide clearance defined between an outer surface of the valve member and an inner surface of the valve guide and wherein the cooling path remains open when the common rail fuel injector is in an injection configuration and/or a non-injection configuration. 15. The common rail fuel injector of claim 14, wherein the control valve includes: a weep annulus positioned on the valve guide; and a weep annulus passage defined within the control valve; and wherein the leakage path includes a heat exchange interface between the weep annulus with the control valve and the weep annulus passage with the control valve. 16. The common rail fuel injector of claim 14 including an armature cavity disposed within an injector body casing, and further including: a cooling clearance defined between an internal surface of the casing and the external surface of the control valve; the cooling path includes the armature cavity and the cooling clearance; and an electrical actuator operably coupled to the control valve. 17. The common rail fuel injector of claim 16 further includes a direct controlled nozzle valve movable between a first position that closes the nozzle outlet and a second position that opens the nozzle outlet; the direct controlled nozzle valve includes an opening hydraulic surface exposed to fluid pressure in a nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in a needle control chamber; and the needle control chamber being fluidly connected to the common rail inlet port when in the non-injection configuration and fluidly connected to fuel drain passage by a valve supply passage.