CLIAMS:We claim:
1. A roller tappet (12) of a high pressure pump (10), said roller tappet (12) comprising:
a U-shaped spring member (14) defined within said roller tappet (12), wherein said roller tappet (12) is coupled to a plunger (16) of said high pressure pump (10); characterized in that
a lubrication oil channel (18) defined within said roller tappet (12) and in flow communication with said U-shaped spring member (14), said lubrication oil channel (18) supplies lubrication oil to said U-shaped spring member (14) to facilitate raising said U-shaped spring member (14).
2. The roller tappet (12) of a high pressure pump (10) in accordance with Claim 1 wherein said lubrication oil channel (18) supplies lubrication oil to said U-shaped spring member (14) further comprises said lubrication oil channel (18) supplies lubrication oil within a groove defined below said U-shaped spring member (14) to facilitate increasing pressure thereby raising said U-shaped spring member (14).
3. The roller tappet (12) of a high pressure pump (10) in accordance with Claim 1 wherein raising said U-shaped spring member (14) raises said plunger (16) which facilitates reducing a pre-stroke of said high pressure pump (10).
4. A high pressure pump (10), said high pressure pump (10) comprising:
a plunger (16);
a roller tappet (12) coupled to said plunger (16) of said high pressure pump (10);
a U-shaped spring member (14) defined within said roller tappet (12); characterized in that
a lubrication oil channel (18) defined within said roller tappet (12) and in flow communication with said U-shaped spring member (14), said lubrication oil channel (18) supplies lubrication oil to said U-shaped spring member (14) to facilitate raising said U-shaped spring member (14).
5. The high pressure pump (10) in accordance with Claim 4 further comprises a groove defined below and in flow communication with said U-shaped spring member (14), said lubrication oil channel (18) supplies lubrication oil within the groove to facilitate increasing pressure thereby raising said U-shaped spring member (14).
6. A fuel injection system, said fuel injection system comprising at least a high pressure pump, said high pressure pump comprising:
a plunger (16);
a roller tappet (12) coupled to said plunger (16) of said high pressure pump (10);
a U-shaped spring member (14) defined within said roller tappet (12); characterized in said high pressure pump
a lubrication oil channel (18) defined within said roller tappet (12) and in flow communication with said U-shaped spring member (14), said lubrication oil channel (18) supplies lubrication oil to said U-shaped spring member (14) to facilitate raising said U-shaped spring member (14). ,TagSPECI:Field of the invention:
[0001] This invention relates to a roller tappet for supplying fuel to a plurality of fuel injectors and a fuel injection system thereof.
Background of the invention:
[0002] Fuel from a fuel tank of an internal combustion engine is supplied to a high pressure pump via a low pressure pump also known as a supply pump and a fuel filter. The high pressure pump is operatively coupled to a series of fuel injectors. Fuel from the low pressure pump is channelled to the high pressure pump, wherein the fuel is then progressively channelled to the fuel injectors and discharged therein. In order to inject fuel from each fuel injector at a particular position of each engine piston, a pre-stroke is required to be set in the high pressure pump. In order to have dynamically varying fuel injection timing during engine operation at varying engine speeds and varying engine loads, it is required to vary the length of pre-stroke in the high pressure pump.
[0003] Chinese Patent Publication Number 203515903-U claims an injection pump oil device that includes a pump body, a pump body set with one plunger set, and a plunger set with one plunger. A plunger set up one wall is provided with an oil inlet hole, the moving direction of the upper plunger piston is provided with an oil outlet hole. The plunger is provided with one upper groove, the inclined direction of the inclined groove is in flow communication with the oil hole. The oil hole is provided with a small hole of the center of a circle in the upper groove. Through this method, this utility new type can contribute to smooth oil injection pump pre-stroke, to pressurize oil and to ensure good injection property.
Brief description of the accompanying drawing:
[0004] An exemplifying embodiment of the invention is explained in principle below with reference to the drawing. The drawing is:
Figure 1 illustrates a front view depicting a high pressure pump used in a fuel injection system of a vehicle.
Detailed description of the invention:
[0005] Figure 1 depicts a roller tappet 12 of a high pressure pump 10 of a vehicle. The roller tappet 12 comprises a U-shaped spring member 14 defined within the roller tappet 12, wherein the roller tappet 12 is coupled to a plunger 16 of the high pressure pump 10. A lubrication oil channel 18 is defined within the roller tappet 12 and in flow communication with the U-shaped spring member 14. The lubrication oil channel 18 supplies lubrication oil to the U-shaped spring member 14 to facilitate raising the U-shaped spring member 14.
[0006] In addition, a high pressure pump 10 is described. The high pressure pump 10 comprises a plunger 16. A roller tappet 12 is coupled to the plunger 16 of the high pressure pump 10. A U-shaped spring member 14 is defined within the roller tappet 12. A lubrication oil channel 18 is defined within the roller tappet 12 and in flow communication with the U-shaped spring member 14. The lubrication oil channel 18 supplies lubrication oil to the U-shaped spring member 14 to facilitate raising the U-shaped spring member 14.
[0007] Moreover, a fuel injection system is described. The fuel injection system comprises a plurality of fuel injectors. A high pressure pump 10 is in flow communication with the plurality of fuel injectors, the high pressure pump 10 comprising a plunger 16, a roller tappet 12 coupled to the plunger 16 of the high pressure pump 10. A U-shaped spring member 14 is defined within the roller tappet 12. A lubrication oil channel 18 is defined within the roller tappet 12 and in flow communication with the U-shaped spring member 14. The lubrication oil channel 18 supplies lubrication oil to the U-shaped spring member 14 to facilitate raising the U-shaped spring member 14.
[0008] In an embodiment, the high pressure pump 10 channels fuel to a fuel injector through an outlet of the high pressure pump 10. Specifically, the high pressure pump 10 channels fuel to the fuel injector via a high pressure common rail by means of a fuel inlet passageway. High pressure pump 10 increases the pressure and therefore controls the flow of fuel supplied through a fuel inlet passageway to the fuel injector via the high pressure common rail. In an embodiment, the high pressure pump 10 is a manual/automated flow rate adjustable pump that controls the flow rate of fuel from the fuel filter to the fuel injector via the high pressure common rail.
[0009] An inlet of the lubrication oil channel 18 is coupled to a lubrication oil supply source while an outlet of the lubrication oil channel 18 is in flow communication with a roller tappet 12 of the high pressure pump 10. The outlet of the lubrication oil channel 18 is coupled to a bottom portion of the U-shaped spring member 14. The U-shaped spring member 14 includes a groove defined at a bottom portion of the U-shaped spring member 14. The groove defined at the bottom portion of the U-shaped spring member 14 facilitates storing lubrication oil that is channeled from the lubrication oil source via the lubrication oil channel 18. When the pressure of lubrication oil at the bottom portion of the U-shaped spring member 14 increases beyond a threshold value, the U-shaped spring member 14 is lifted upwardly. When the U-shaped spring member 14 is lifted upwardly, a pre-stroke associated with the high pressure pump 10 decreases. The displacement of the U-shaped spring member 14 in the upward direction is proportional to the pressure and quantity of lubrication oil that is supplied to the bottom portion of the U-shaped spring member via the lubrication oil channel 18.
[00010] The fuel injection system includes an engine control unit. The engine control unit controls the flow of lubrication oil to the bottom portion of the U-shaped spring member 14. In an embodiment, the engine control unit facilitates channeling a metered quantity of lubrication oil from the lubrication oil source to the bottom portion of the U-shaped spring member 14. Specifically, from an instantaneous value of engine speed and an instantaneous value of engine load, the engine control unit determines a displacement that needs to be applied to the U-shaped spring member 14 to vary the pre-stroke of the high pressure pump 10.
[00011] The operation of the high pressure pump 10 is now described as an example. When the vehicle is in an operative state, the instantaneous engine speed and the instantaneous engine load is determined by the engine control unit. Based on the instantaneous engine speed and the instantaneous engine load, the engine control unit channels a metered quantity of lubrication oil via the lubrication oil channel 18 to the groove defined at the bottom portion of the U-shaped spring member 14. Therein, the U-shaped spring member 14 is lifted upwardly due to an increase in pressure of lubrication oil, thereby facilitating lifting the plunger 16 in the upward direction. The upward movement of the plunger 16 facilitates decreasing a pre-stroke of the high pressure pump 10. The decrease in the pre-stroke of the high pressure pump 10 is proportional to the quantity of lubrication oil that is metered from the lubrication oil source to the bottom portion of the U-shaped spring member 14. Therefore, by varying the quantity of lubrication oil that is channeled to the groove defined at the bottom portion of the U-shaped spring member 14, it is possible to vary the pre-stroke of the high pressure pump 10 dynamically with varying instantaneous engine speed and the instantaneous engine load.
[00012] The above described roller tappet 12 for varying the pre-stroke of the high pressure pump 10 of a vehicle is cost effective and highly reliable. The lubrication oil channel 18 for supplying lubrication oil to the bottom portion of the U-shaped spring member 14 facilitates decreasing a pre-stroke of the high pressure pump 10. The decrease in the pre-stroke of the high pressure pump 10 is proportional to the instantaneous engine speed and the instantaneous engine load. In addition, the modular nature of each sub-system of the high pressure pump 10 facilitates easy disassembly and replacement of individual system components as required.
[00013] It must be understood that the embodiments explained in the above detailed description in only illustrative to explain the working of the lubrication oil channel 18 that supplies lubrication oil to the bottom portion of the U-shaped spring member 14 as claimed and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.