Claims:We Claim
1. A fuel injector (10) for controlling a flow of fuel to an engine, said fuel injector (10) comprising:
a housing (12); 5
an injector needle (14) positioned within a nozzle body (15), said injector needle (14) adapted to be lifted to facilitate injecting fuel out of said fuel injector (10); characterized in that
a drive unit (16) comprising a motor unit (18) and a motor shaft (20) secured to said motor unit (18) positioned within said fuel injector (10), said motor unit (18) 10 adapted to rotate said motor shaft (20) to facilitate delivering a metered quantity of fuel out of said drive unit (16) via an outlet port of said motor shaft (20); and
a fuel passageway (25) defined between the outlet port of the motor shaft (20) and said injector needle (14), said fuel passageway (25) adapted to channel the metered quantity of fuel from the outlet port of said motor shaft (20) to the nozzle body (15) 15 controlling the lifting of the nozzle needle (14). , Description:[0001] Field of the invention
This invention relates to a diesel fuel injector and more specifically to a fuel injector for controlling a flow of fuel to an engine.
[0002] Background of the invention 5
IN Patent Application Number 201741026746 describes a fuel injector for controlling a flow of fuel to an engine. The fuel injector comprises a housing, and an injector needle positioned within a nozzle body, the injector needle adapted to be lifted to facilitate injecting fuel out of the fuel injector. A drive unit comprising a motor unit and a motor shaft is secured to the motor unit that is positioned above the injector needle and within the 10 fuel injector. The motor unit is adapted to rotate the motor shaft to facilitate delivering a metered quantity of fuel out of the drive unit.
[0003] Brief description of the accompanying drawings
[0004] Figure 1 illustrates a cross-sectional drawing of a drive unit that is integrated with 15 a fuel injector for controlling a flow of fuel to an engine.
[0005] Figure 2 illustrates a schematic diagram of a drive unit, motor unit, and a motor shaft that is secured to the motor unit.
[0006] Figure 3 illustrates a working principle of control of fuel injection characteristics by the fuel injector. 20
[0007] Detailed description of the invention
A fuel injector 10 for controlling a flow of fuel to an engine is described. The fuel injector 10 comprises a housing 12 and an injector needle 14 positioned within a nozzle body 15, the injector needle 14 adapted to be lifted to facilitate injecting fuel out of the fuel injector 25 10. A drive unit 16 comprising a motor unit 18 and a motor shaft 20 secured to the motor unit 18 and positioned within the fuel injector 10, the motor unit 18 adapted to rotate the motor shaft 20 to facilitate delivering a metered quantity of fuel out of the drive unit 16 via an outlet port of the motor shaft 20. A fuel passageway 25 is defined between the outlet of the motor shaft 20 and the injector needle 14, the fuel passageway 25 adapted to channel 30
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the metered quantity of fuel from the outlet port of the motor shaft 20 to the nozzle body 15, thereby controlling a lifting of the nozzle needle 14.
[0008] Figure 1 illustrates a schematic diagram of a drive unit 16 integrated with a fuel injector 10 for controlling a flow of fuel to an engine. The fuel injector 10 comprises the 5 drive unit 16 that may be inserted within the fuel injector 10. A fuel pump (not shown) is in flow communication with the fuel injector 10 and supplies pressurized fuel to the fuel injector 10. The fuel injector 10 comprises an injector needle 14 that is positioned within a bore of a nozzle body 15 within the fuel injector 10 and controls a flow of fuel out of the fuel injector 10. A spring chamber 32 is defined above the injector needle 14 and houses a 10 spring member 33 therein.
[0009] The drive unit 16 of the fuel injector 10 comprises a motor unit 18 and a motor shaft 20 that is secured to the motor unit 18. The motor shaft 20 comprises at least a first fuel passage 22 and a second fuel passage 24 that is orthogonal to and in flow communication 15 with the at least first fuel passage 22. The second fuel passage 24 is in flow communication with a fuel outlet port of the motor shaft 20. The fuel outlet port of the motor shaft 20 is in flow communication with a fuel passageway 25 that is defined between the outlet port of the motor shaft 20 and the nozzle body 15. The fuel passageway 25 is adapted to channel a metered quantity of fuel from the outlet port of the motor shaft 20 to the nozzle body 15. 20
[0010] The first fuel passage 22 that is provided in the motor shaft 20 may be aligned with a leak off bore (not shown) in the housing 12 of the fuel injector 10. When the first fuel passage 22 is aligned with the leak off bore, then the fuel in the second fuel passage 24 is in flow communication with the leak off bore in the housing 12 of the fuel injector 10. 25
[0011] Figure 2 illustrates a schematic diagram of a motor unit 18 and a motor shaft 20 that is secured to the motor unit 18. The motor shaft 20 includes the first fuel passage 22 that is defined on the motor shaft 20. The drive shaft rotates and aligns the first fuel passage 22 partially or fully with the fuel passage 26 to facilitate receiving fuel from the fuel passage 30 26.
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[0012] Figure 3 illustrates a schematic diagram of the working of the fuel injector 10. The motor unit 18 is controlled by an electronic control unit to decide the timing of when to rotate and the extent of rotation of the motor shaft 20 depending on the engine speed and load conditions to inject an accurate quantity of fuel at a desired time. When the drive unit 5 16 receives the signal from the electronic control unit, the motor shaft 20 which is secured to the motor unit 18 rotates accurately to the desired value based on the input signal from the electronic control unit. The first fuel passage 22 that is defined on the motor shaft 20 rotates and aligns either with the fuel passage 26 or with the leak off bore (not shown) in the injector housing 12. 10
[0013] High pressure fuel from the fuel pump (not shown) enters the fuel passage 26. When the fuel passage 22 is aligned with the fuel passage 26, fuel from the fuel passage 26 enters the first fuel passage 22 and finally into the fuel passageway 25 via the second fuel passage 24. This pressurized fuel in the fuel passageway 25 enters the nozzle body 15 and applies 15 pressure on the nozzle needle 14, and this creates an upward force on the nozzle needle 14.
[0014] The high pressure fuel from the fuel pump (not shown) also flows towards the nozzle body 15 through the fuel passage 25 and applies the pressure on the nozzle needle 14. This creates an upward force on the nozzle needle 14. The nozzle needle 14 is in the 20 closed condition due to preset spring force acting on it due to the spring member 33. As fuel from the fuel passage 25 enters the nozzle body 15, the line pressure goes on increasing and upward force is applied by fuel pressure on the nozzle needle 14. Once the upward force due to fuel pressure on the nozzle needle 14 exceeds the downward force on the nozzle needle 14 due to the spring 33, the needle lifts in the upward direction and fuel gets 25 injected out of the fuel injector 10 through spray holes that are provided (not shown) in the nozzle body 15.
[0015] When the desired quantity of fuel is injected out of the fuel injector 10, the electronic control unit 17 sends the signal to the drive unit 16. The motor unit 18 in the 30 drive unit 16 rotates the motor shaft 20. The first fuel passage 22 that is provided in the
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motor shaft 20 rotates. The fuel passage 26 no more aligns with the first fuel passage 22. Fuel flowing through fuel passage 26, 22, and 24 and then to nozzle body 15 ceases and fuel pressure drops in the nozzle body 15. Due to this upward force acting on the nozzle needle 14 due to the fuel pressure reduces and then finally ceases, the nozzle needle 14 closes by moving in the downward direction due to the spring force acting on nozzle needle 5 14 due to the spring member 33 and hence fuel flowing out of the fuel injector 10 ceases.
[0016] Partial alignment (as shown in the figure 3) of the first fuel passage 22 with the fuel passageway 26 helps to control the quantity of fuel and the rate of fuel injection. Pilot, post and damped / boot injection characteristics can be realized through partial alignment of the 10 first fuel passage 22 with the fuel passage 26 as shown in the second representation of figure 3. Full alignment of the first fuel passage 22 and the fuel passage 26 as shown in the third representation of figure 3 results in main injection. The duration of alignment of the first fuel passage 22 with the fuel passage 26 controls the duration of fuel injection. The time at which the first fuel passage 22 and the fuel passage 26 align with each other controls 15 the fuel injection timing or the instant at which the fuel injection begins from the fuel injector.
[0017] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with 20 regard to leverage and dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.