FIELD OF THE INVENTION

This invention relates to a fuel supply device in a vehicle.

In particular, this invention relates to a fuel supply device for an internal combustion engine.

BACKGROUND OF THE INVENTION

An internal combustion (IC) engine using diesel fuel works on a compression-ignition principle. As the name suggests in the compression-ignition principle, the diesel fuel has to be compressed to a high pressure value. The increase in pressure of the diesel increases the temperature of the diesel. The heat of compression of the diesel fuel is used to initiate ignition and burn the fuel in the combustion chamber of the diesel IC engine. Diesel IC engines do not use any igniters or spark plugs to ignite the fuel as the pressure and temperature of the diesel fuel is enough to ignite the fuel. However, one of most important aspects of a diesel IC engine is that the diesel has to be maintained at a particular pressure which aids in igniting the diesel fuel after it is introduced in the combustion chamber. To maintain pressure of diesel entering the combustion chamber, fuel supply devices known in the state of the art employ a common rail (Accumulator). The common rail type fuel injection systems house the add-on components such as Rail pressure sensor (RPS), Pressure control valve (PCV), sometimes a screw-plug. The rail has threaded connectors, depending on the number of cylinders/injectors in the specific system as outlet ports and corresponding inlet connector(s) to take-up the fuel from high pressure pump.

In a common rail type fuel supply device at least some volume of the diesel in always present in the common rail which helps in damping the pressure oscillations coming from the system. The common rail has two variants in terms of manufacturing. The first "LWR" Laser Welded Rail, employs the concept of machining the product from bar stock and then employing the process of Laser welding to fit-in the threaded connectors for high pressure pipes to injectors and from high pressure pump. The second concept, has forging as the basic principle of evolving the product geometry and then employs the machining for achieving the final geometries. The key factor that needs attention in the product is the fatigue strength, which is critical in achieving the lifetime requirements under the pulsating pressure loads. A pulsation test involving various pulsating pressures levels has to be successfully completed in order that the product be released for the application. (For eg: a pressure level means - pressure ranging from 50bar to 2400bar, Max pressure depending on the final pressure level that the product has to be released).

However, there are some disadvantages associated with the use and manufacturing of the common rail type fuel supply device. One of the disadvantages of the common rail type fuel supply device is that if there is even the slightest machining error in manufacturing the common rail would lead to failures in terms of pressure with-holding capacity in the rail. This pressure failure in the common rail would completely upset the injection and ignition cycle in a diesel IC engine. An error during welding in threaded connectors would add to the same failure as above. To Summarize, further to withstand not only the pressure pulsations but also to be able to store high pressure fuel in the common rail the material & processes has to be of a high standard. This would increase the cost of a fuel supply device which is implemented through a common rail type of device.

In case of modern low cost vehicle, where the main aim is to reduce the cost of the vehicle the use of the common rail increases the cost of the fuel supply device and in turn the overall cost of the vehicle. Particularly in case of small capacity engines such as one or two cylinder engines the use of the common rail increases the cost of the fuel supply device and in turn the overall cost of the vehicle. Further in case of lower capacity engines it is not necessary to maintain the pressure of large amount of fuel which is typically in the range of 10-16cc in a rail from a 3-4 cylinder engine, over a long period of time since the amount of fuel to be injected in the combustion chamber is much lower than in an engine which has three cylinders or more.

It is an object of this invention is to overcome the limitations of the conventional common rail type fuel supply devices.

ADVANTAGES OF THE INVENTION

The advantages of the invention as claimed in the independent claim are as follows. The fuel supply device of this invention has a fuel distributor block and a pressure sensor integrated in the fuel distributor block. This has the advantage that use of a common rail type (accumulator) of fuel supply device can be eliminated. In case of lower capacity engines such as one and two cylinder engines which do not require that the pressure be maintained over a long period of time the use of the fuel supply device in accordance with this invention has the advantage of being able to supply pressurized fuel to the injectors. Further the process of manufacturing the fuel supply device in accordance with this invention is much easier due to its compact size in comparison to rail. The cost of manufacturing the fuel supply device is much lower than that for manufacturing the common rail. Further, the fuel supply device has an integrated pressure sensor. The integrated pressure sensor provides the advantage of being able to monitor the pressure of fuel which is sent to the injectors to be injected into the combustion chamber in a diesel IC engine.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

DETAILED DESCRIPTION

Figure 1 illustrates the fuel supply device in accordance with this invention. The fuel supply device 10 for an internal combustion engine comprises a fuel distributor block 12; a recess 14 is located at one end 16 of the fuel distributor block 12. A first bore 18 extends from the recess 14 to a second end 20 of the fuel distributor block 12. A second bore 22 is perpendicular to the first bore. A pressure sensor 24 is located in the recess 14. The pressure sensor 24 is an electronic controlled sensor which is housed in a housing 26. A housing 26 as seen in figure 1 is located in the recess 14 at the end 16 of the fuel distributor block. The housing 26 holds all the components which allows the pressure sensor 20 to communicate with an electronic control unit (not shown in the drawings) which controls the fuel injection cycles of an engine. The housing 26 is screw fit into the recess 14. The pressure sensor 24 is electronic controlled this ensures accuracy of measurement and better control of fuel injection cycles.

The recess 14, the first bore 18 and the second bore 22 are internal to the fuel distributor block. On the external surface the fuel distributor block 12 has at least three threaded interfaces. A first threaded interface 28 corresponding to the first bore 18 opening at the second end 20 of the fuel distributor block 12. A second 30 and third threaded 32 interface one each corresponding to the two ends of the second bore 22. The first threaded interface 28 acts as the inlet for the high pressure fuel coming from a fuel pump outlet. The second 30 and the third 32 threaded interface acts as the outlet which supplies high pressure fuel to plurality of injectors.

The recess 14 is provided with an internal thread which is used to screw in the housing 26 to the fuel distributor block 12. The pressure sensor 24 located in the housing 26 communicates with an electronic control unit through the components in the housing 26.

Figure 2 illustrates a cut-section of the fuel distributor block 12 in accordance with this invention and Figure 3 illustrates a cut-section of the fuel distributor block 12 with the housing 26 fitted in fuel distributor block 12. While manufacturing the fuel distributor block 12 , with the right material care is taken that the sealing surfaces/ Intersections of the fuel distributor block 12 has specific geometric and form tolerances which ensure that it is able to withstand the high pressure exerted by the pressurized fuel which is received by the fuel distributor block 12 from a high pressure fuel pump and delivered to pluralities of injectors. Further, the portion of the first bore 18 and the second bore 22 which intersection are designed in a manner such that it avoids any crack initiation in the fuel distributor block 12 which may occur due to pulsating pressure levels that may be present at the intersection.

Another important aspect of the fuel distributor block 12 in accordance with this invention is the formation of the recess 14. The diameter of the recess 14 opening at the end 16 of the fuel distributor block 12 is larger than the opening of the recess 14 which is opens up into the first bore 18. Due to the difference in diameters at the two end of the recess 14, a seat 34 is formed on which the housing 26 is seated when the fuel supply device 10 is in its operative configuration. When the housing 26 is screw fit into the seat 34, the pressure sensor 24 located in the housing 26 in a manner such that pressure sensor is in fluid communication with the pressurized fuel entering the fuel distributor block via the first bore 18. It is ensured by the right design parameters and manufacturing processes that there is no leakage of high pressure fuel at this sealing surface.

While designing the fuel distributor block 12 care has to be take that the distance between the seat 34 formed by one end of the recess and the cross hole intersection of the first bore 18 and the second bore 22 is such that it can withstand the pressure exerted by the high pressure fuel entering the first bore 18. The postioning of the recess 14 in context with the positioning of the first bore 18, second bore 22 and the intersection of the two bores 18 and 22 ensures optimum fatigue strength to the fuel distributor block.

The size of the first bore 18 and the second bore 22 also ensures that there is minimum volume of accumulated fuel in the fuel distributor block. This has the advantage that there is no issue with development and management of pressure pulsations within the fuel distributor block. Particularly in case of smaller capacity engines wherein the amount of fuel to be injected and the frequency of fuel injection is lesser, the variation in pressure within the fuel distributor block 12 are not such a common occurrence. Hence there is no need to any volume of fuel to be present in the fuel distributor block. Since there is minimum requirement of fuel volume to be present this reduces the over size of the fuel distributor block and reduces cost.

It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the invention. Many modifications in embodiments are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.

WE CLAIM:

1. A fuel supply device (10) for an internal combustion engine comprising:

(i) a fuel distributor block (12), a recess (14) located at one end (16) of said fuel distributor block(12), a first bore (18) extending from base of said recess (14) to a second end (20) and a second bore (22) perpendicular to said first bore (18); and

(ii) a pressure sensor (24) located in said recess (14).

2. The fuel supply device (10) as claimed in claim 1, wherein said pressure sensor is located in a housing (26).

3. The fuel supply device (10) as claimed in claim 2, wherein said housing is located in said recess (14).

4. The fuel supply device (10) as claimed in claim 1, wherein said fuel distributor block (12) comprises a first threaded interface (28) corresponding to the first bore (18) and the second end (20) of the fuel distributor block (12).

5. The fuel supply device (10) as claimed in claim 1, wherein said fuel distributor block (12) comprises a second threaded interface (30) and third threaded interface (32) one each corresponding to the two ends of the second bore (22).

6. The fuel supply device (10) as claimed in claim 1, wherein fuel from a fuel pump enters said fuel distributor block from the first threaded interface (28) via said first bore (18).

7. The fuel supply device (10) as claimed in claim 1, wherein said fuel is supplied to pluralities of injectors via said second bore through said second threaded interface (30) and third threaded interface (32).

8. The fuel supply device (10) as claimed in claim 1, wherein cross holes are provided at the intersection of said first bore (18) and said second bore (22).

9. The fuel supply device (10) as claimed in claim 1, wherein a seat (34) is formed at the recess due to the difference in diameter of said recess (14) opening at the end (16) of said fuel distributor block 12 and the opening of the recess (14) which is opens up into said first bore (18).

10. The fuel supply device (10) as claimed in claim 1, 2 and 9, wherein said housing (26) is located on said seat (34) in said recess (14) in said fuel distributor block (12).