Claims:
1 A mechanical fuel injector (100) for a vehicle, said mechanical fuel injector (100) comprising:
an injector body (12), the injector body (12) comprising:
a cavity (14);
an inlet path (16) for supplying fuel into said cavity (14);
a piston (18) movable within said cavity (14) for pressurizing said fuel in said cavity (14);
a first plate (20) fitted to said injector body (12) and comprising a first orifice (20a), said first orifice (20a) in flow communication with said cavity (14) for receiving said pressurized fuel from said cavity (14); and
a second plate (22) biased against the first plate (20) by a resilient member (24) and comprising a second orifice (22a), wherein said first orifice (20a) and said second orifice (22a) are non-collinear, said second plate (22) adapted to be displaced against said resilient member (24) by said pressurized fuel flowing through said first orifice (20a), into said second plate (22), for discharging said pressurized fuel into a combustion chamber (26) through said second orifice (22a) located in said second plate (22).

2 The mechanical fuel injector (100) as claimed in claim 1, wherein said resilient member (24) is a spring.

3 The mechanical fuel injector (100) as claimed in claim 1 further comprising a third plate (28) fitted to said first plate (20), and comprising a receptacle (28b), located at central portion of said third plate (28), extending towards said combustion chamber (26) and enclosing said second plate (22) in a manner such that said second plate (22) is movable against resilient member (24) within said receptacle (28b) located in said third plate (28).

4 The mechanical fuel injector (100) as claimed in claim 3, wherein said first plate (20) and said third plate (28) are fitted using a screw fit mechanism.

5 The mechanical fuel injector (100) as claimed in claim 3, wherein said third plate (28) comprises a third orifice (28a) for discharging said pressurized fuel into said combustion chamber (26).

6 The mechanical fuel injector (100) as claimed in claim 1, wherein said piston (18) is movable within said cavity (14) based on movement of a cam shaft of said vehicle.
, Description:Field of the invention:
[0001] The invention relates to a mechanical fuel injector of a vehicle.

Background of the invention:
[0002] A fuel injector is an important component in a fuel injection system for injecting fuel into a combustion chamber of an engine. Mechanical injector can be made more robust with the addition of electronic circuitry or by replacing it with an electronic injector. This adds to the overall of cost of the fuel injection system. In cases where the flow of fuel into the mechanical injector is by gravity flow, opportunities exist for utilizing the action of gravity itself to pressurize the fuel before injecting the same in the combustion chamber.
[0003] According to US 5239969, an apparatus for injecting fuel into an internal combustion engine is disclosed. The apparatus comprises a hollow injector body having a cylindrical bore, a compression head closing one end of said bore, a pump head closing an opposite end of said bore; a plunger piston reciprocally moveable within said cylinder bore defining a variable volume fuel pumping chamber formed by said injector body, said compression head, and a first end of said piston, and a variable volume compression chamber formed by said injector body, said pump head and a second end of said piston, fuel supply means connected to said pumping chamber, fuel passage means interconnecting said pumping chamber, said compression chamber and said fuel supply means, air supply means connected to said fuel passage means, fuel/air discharge means connected to said compression chamber, an injection nozzle located in said engine and connected to said fuel/air discharge means for injecting a mixture of fuel and air into said engine for combustion therein and an actuator means operably interconnecting said piston and said engine for reciprocating said piston within said cylinder bore of said injector body.

Brief description of the accompanying drawings:
[0004] Figure 1 is a cross sectional view of a mechanical fuel injector of a vehicle, in accordance with one embodiment of the present disclosure.

Detailed description of the embodiments:
[0005] The present disclosure discloses a mechanical fuel injector (100) of a vehicle. The mechanical fuel injector (100) comprises an injector body (12), the injector body (12) comprising a cavity (14), an inlet path (16) for supplying fuel into the cavity (14), a piston (18) movable within the cavity (14) for pressurizing the fuel in the cavity (14). The mechanical fuel injector (100) also comprises a first plate (20) fitted to the injector body (12) and in flow communication with the cavity (14) and comprising a first orifice (20a) for receiving the pressurized fuel from the cavity (14) and a second plate (22) biased against the first plate (20) by a resilient member (24) and comprising a second orifice (22a), wherein the first orifice (20a) and the second orifice (22a) are non-collinear, the second plate (22) adapted to be displaced against the resilient member (24) by the pressurized fuel flowing through the first orifice (20a), into the second plate (22), for discharging the pressurized fuel into a combustion chamber (26) through the second orifice (22a) located in the second plate (22).
[0006] Construction of the mechanical fuel injector (100) is explained in conjunction with Figure 1.
[0007] Figure 1 is a cross sectional view of a mechanical fuel injector (100) of a vehicle, in accordance with one embodiment of the present disclosure.
[0008] The injector body (12) forms the outer covering of the mechanical fuel injector (100). The injector body (12) comprises a cavity (14). This cavity (14) is a cylindrical bore extending along length of the injector body (12).
[0009] The injector body (12) also comprises an inlet path (16). The inlet path (16) is a flowpath that is in fluid communication with the cavity (14), in the injector body (12), for supplying fuel to the cavity (14). The inlet path (16) is defined in the injector body (12) for enabling flow of fuel into the cavity (14). This inlet path (16) is connected to a fuel tank of the vehicle. The fuel from the fuel tank is fed to the inlet path (16) through gravity and thus supplied to the cavity (14).
[0010] The mechanical fuel injector (100) also comprises a piston (18) movable within the cavity (14). That is, the piston (18) is adapted to reciprocate within the cavity (14). The piston (18) is connected to a cam shaft of the vehicle. The piston (18) is movable within the cavity (14) based on the movement of the cam shaft of the vehicle. That is, the movement of the cam shaft is imparted to the piston (18) such that the piston (18) reciprocates within the cavity (14). The reciprocatory movement of the piston (18), within the cavity (14), pressurizes the fuel supplied to the cavity (14) through the inlet path (16).
[0011] The piston (18) includes a groove (30) defined along the longitudinal axis of the piston (18). The groove (30) is adapted to be in fluid communication with the inlet path (16) for allowing fuel to flow into the cavity (14) based on rotation of the piston (18). A control rod (not shown in Figure 1) rotates the piston (18) such that the groove (30) establishes fluid communication with the inlet. The control rod is operated based on the fuel demand provided by a driver of the vehicle. The control rod is also adapted to rotate the piston (18) such that the fluid communication between the inlet path (16) and the groove (30) is cut-off and hence no fuel is supplied to the cavity (14). Therefore, the supply of fuel into the cavity (14) is obtained based on the rotation of the piston (18) by the control rod.
[0012] The mechanical fuel injector (100) also includes a first plate (20) fitted to the injector body (12). The first plate (20) is a circular plate located downstream of the inlet path (16). The first plate (20), in one example, may be screw fitted to the injector body (12). The first plate (20) comprises a first orifice (20a) in flow communication with the cavity (14) for receiving the pressurized fuel from the cavity (14). The first orifice (20a) located in the first plate (20) is directly guided into a combustion chamber (26). The first orifice (20a) functions as a nozzle hole for discharging the pressurized fuel from the cavity (14).
[0013] The mechanical fuel injector (100) also includes a second plate (22) biased against the first plate (20) by a resilient member (24). The resilient member (24), in one example, is a spring. The second plate (22) comprises a second orifice (22a). The first orifice (20a) and the second orifice (22a) are non-collinear with each other. Hence, when the second plate (22) biased against the first plate (20) by a resilient member (24), the second orifice (22a) is sealed and hence no fuel is allowed to flow through the second orifice (22a).
[0014] The second plate (22) is adapted to be displaced against force exerted by the resilient member (24) by the pressurized fuel flowing through the first orifice (20a) into the second plate (22). Displacement of the second plate (22) creates a clearance between the first plate (20) and the second plate (22) such that the second orifice (22a) is unsealed and hence the pressurized fuel can be discharged into the combustion chamber (26). The combustion chamber (26) comprises the inlet valve (26a) for air and the outlet valve (26b).
[0015] A third plate (28) is fitted to the first plate (20). The third plate (28) comprises a receptacle (28b) located at a central portion of the third plate (28) and the receptacle (28b) being extending away from the first plate (20) towards a Top Dead Center of the combustion chamber (26). The receptacle (28b) is closed at end opposite to the first plate (20) and encloses the second plate (22). The receptacle (28b) in the third plate (28) houses the resilient member (24) in a manner such that the second plate (22) is movable against resilient member (24) within the receptacle (28b) located in the third plate (28). In other words, the diameter of the central portion of the third plate (28) is marginally larger with respect to diameter of the second plate (22) so that diameter of the receptacle (28b) in the third plate (28) concentrically encloses the second plate (22).That is, the third plate (28) encloses the second plate (22) in a manner such that the second plate (22) is movable against the force exerted by the resilient member (24) within the receptacle (28b) located in the third plate (28). The third plate (28) is fitted to the first plate (20) using screw fit mechanism at the periphery of the third plate (28). In one embodiment, the receptacle (28b) is a square-shaped or rectangular shaped extending towards the combustion chamber (26). In another embodiment, the receptacle (28b) is a concave shaped extending towards the combustion chamber (26).
[0016] The third plate (28) comprises a third orifice (28a) for discharging the pressurized fuel flowing through the second orifice (22a) into the combustion chamber (26). The third orifice (28a) is used for enabling flow of the pressurized fuel without any obstacle. Size of the third orifice (28a) is large when compared to size of the first orifice (20a) and the second orifice (22a).
[0017] Working of the mechanical fuel injector (100) is explained in detail in the below paragraphs.
[0018] Fuel from the fuel tank flows through the inlet path (16) and enters into the cavity (14), in the injector body (12), when the groove (30) in the piston (18) establishes fluid communication with the inlet path (16). The reciprocatory movement of the piston (18) within the cavity (14) of the injector body (12) pressurizes the fuel in the cavity (14). That is, as the piston (18) tends to move towards end of the cavity (14) (proximal to the top dead center of the combustion chamber (26)), the fuel in the cavity (14) is pressurized. The reciprocatory movement of the piston (18) is caused due to the movement of the cam shaft.
[0019] The pressurized fuel from the cavity (14) strikes the first plate (20). It should be noted that, the first plate (20) and the second plate (22) are abutted against each other. Hence, the second orifice (22a) located in the second plate (22) is sealed as the first orifice (20a) and the second orifice (22a) are non-collinear with respect to each other. As the pressurized fuel flows through the first orifice (20a) located in the first plate (20), it strikes the second plate (22). When pressure of the pressurized fuel flowing through the first orifice (20a) is greater than the force exerted by the resilient member (24), the second plate (22) is displaced from its position. That is, the resilient member (24) compresses causing the second plate (22) to displace from its position. Such displacement of the second plate (22) creates a clearance with respect to the first plate (20). Such clearance causes unsealing of the second orifice (22a) and hence the pressurized fuel is discharged into the combustion chamber (26) through the second orifice (22a) located in the second plate (22).
[0020] Further, the pressurized fuel also flows into the combustion chamber (26) through the third orifice (28a) present in the third plate (28) for enabling free flow of pressurized fuel into the combustion chamber (26).
[0021] Therefore the present disclosure discloses a fuel injector (100) for enabling gasoline direct injection through gravity feed mechanism. However, it should be noted that the fuel injector (100) is not limited for gasoline alone and also can be used for injecting diesel fuel. Since it works by gravity feed mechanism, the need for electric feed pump for pumping pressurized fluid is eliminated. The fuel injector (100) does not require any electric components, such as a solenoid for its functioning. Therefore it is robust, easily serviceable and also economical.
[0022] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. The scope of the invention is only limited by the scope of the claims.