Field of the invention

This invention relates to a fuel injection pump. More particularly, the invention relates to preventing rotation of a barrel in the mechanical fuel injection pump.

State of the art

In order to permit the changes in fuel delivery quantity of the fuel injection pump, an annular slot is machined on to the plunger of the fuel injection pump. Such an annular slot is known as a helix. An eccentric pin is inserted in a hole provided in the housing of the fuel injection pump to maintain an appropriate position relationship between the helix of the plunger and a fuel inlet port of a barrel. This is performed to set a suitable fuel delivery quantity of the fuel injection pump. However, the retention force by the eccentric pin is not so strong. Especially, the position of the barrel gets disturbed when a delivery valve is removed from the fuel injection pump for servicing or testing the fuel injection pump.

When the barrel is rotated, the positional relationship between the helix in the plunger and the inlet port of the barrel gets affected. The repositioning process is cumbersome and takes lot of time.

Description of the invention

The invention comprises a fuel injection pump, a locking means for a fuel injection pump. The invention also discloses a method for assembling and/or dismantling a fuel injection pump. The fuel injection pump comprises a barrel positioned inside a pump housing. The barrel includes a passage. A locking element is inserted into the passage to prevent the rotation of the barrel. The passage may be a fuel inlet port of the barrel. The locking element may be detachedly inserted into the fuel inlet port of the barrel through a fuel supply passage of the housing. Unintended rotation of the barrel can be prevented, by simply inserting the locking element inside the fuel inlet port through the fuel supply passage. Thus, the position relationship between the helix of the plunger and the fuel inlet port does not get affected. Therefore, undesired change in the fuel delivery quantity setting is avoided. The locking element may be formed integrally in the fuel injection pump to prevent the rotation of the barrel.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

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

Figure 1 shows a schematic view of a fuel injection pump in accordance with an embodiment of the present invention;

Figures 2a shows a fuel injection pump without a locking element;

Figure 2b shows the fuel injection pump with the locking element inserted inside a fuel supply passage and a fuel inlet port;

Figure 3 shows a locking element and a clamping screw in accordance with one embodiment of the present invention; and

Figure 4 shows a locking means for a barrel of a fuel injection pump, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a schematic view of a fuel injection pump, in accordance with the embodiment of the invention. The fuel injection pump 10 is a mechanical pump, which is driven by a cam. The fuel injection pump 10 comprises a housing 12 having a barrel 14.

A plunger 16 driven by the cam is reciprocatably movable inside the barrel 14. A delivery valve holder 18 is fixed over the barrel 14. The delivery valve holder 18 holds in position a delivery valve through which fuel is delivered to the engine. The reciprocating movement of the plunger 16 in the barrel 14 causes the fuel to be pumped to the delivery valve. The barrel 14 has a passage 20, in which one or more locking elements are inserted to prevent the rotation of the barrel 14.

A helix 24 is machined on the outer surface of the plunger 16. Typically, the barrel 14 is held with the help of an eccentric pin such that the fuel inlet port 20 of the barrel 14 is maintained in a certain position relationship with respect to the helix 24 of the plunger 16. This is done to set the fuel delivery quantity of the fuel injection pump 10.

During certain situations, the delivery valve holder 18 has to be removed from the fuel injection pump 10. For example, the delivery valve holder 18 is removed from the fuel injection pump 10 for servicing the components of the fuel injection pump 10.

Further, the delivery valve holder 18 is removed while testing the fuel injection pump 10. For instance, in order to do a static-injection-timing (SIT) test, the delivery valve holder 18 is removed from the fuel injection pump 10. Then, a SIT testing tool is connected in place of the delivery valve holder 18 for conducting the SIT test.

When removing the delivery valve holder 18 from the fuel injection pump 10 and assembling it again, the position of the barrel 14 gets disturbed. Since the barrel 14 is rotated, the position relationship between the helix 24 of the plunger 16 and the fuel inlet port 20 gets disturbed.

In an embodiment of the invention, the passage 20 is a fuel inlet port 20 of the barrel 14.

The housing 12 has a fuel supply passage 22, through which fuel is supplied from a tank to the barrel 14.

Figure 2a shows a fuel injection pump without the locking element. In order to prevent the rotation of the barrel 14, a locking element 26 is detachedly inserted into the fuel inlet port 20 through the fuel supply passage 22. The fuel injection pump 10 with the locking element 26 in inserted condition is shown in the figure 2b. The locking element 26 is inserted into the fuel inlet port 20 through the fuel supply passage 22. A screw 28 may be fixed over the locking element 26 to retain it in the fuel supply passage 22 and in the fuel inlet port 20.

Figure 3 shows a locking element used in a fuel injection pump in accordance with one embodiment of the present invention. In an example, as shown in figure 3, the locking element 26 is in the form of a spindle. One end 30 of the locking element 26, which is inserted into the fuel inlet port 20, is of spherical shape. The end 30 of the locking element 26 may of any shape which is matching or complementary to the shape of the fuel inlet port 20. Inserting the end 30 of the locking element 26 in the fuel inlet port 20 arrests the rotation of the barrel 14. The locking element 26 is inserted into the fuel inlet port 20 to prevent the rotation of the barrel 14 when removing the delivery valve holder 18 from the fuel injection pump 10. Further, the locking element 26 is inserted again into the fuel inlet port 20 while attaching the delivery valve holder 18 to the fuel injection pump 10, to prevent the rotation of the barrel 14.

The locking element 26 may be in the form of a spindle, a pin or a projection. The thickness of the locking element 26 may be equal to the inner diameter of the fuel supply passage 22 of the housing 12.

Figure 4 shows a locking means for a barrel of a fuel injection pump, in accordance with an embodiment of the invention. The fuel injection pump 10 comprises a locking means 32. The locking means 32 is adapted to prevent the rotation the barrel 14, during assembly and/or dismantling of a delivery valve holder 18. The locking means 32 is integrally provided in the barrel 14 of the fuel injection pump 10.

In this embodiment of the invention, the locking means 32 is in the form of one or more projections 32 that are integrally formed on the outer surface of the barrel 14. One or more recesses 34 are provided at the inner surface of the housing 12 corresponding to the number of projections 32. The projections 34 are selectively inserted into the recesses 34 to prevent the rotation of barrel 14.

In yet another embodiment, the locking means is integrally formed at the inner surface of the housing 12 of the fuel injection pump 10. The locking means is in the form of one or more projections provided at the inner surface of the housing 12. The barrel 14 has one or more recesses on its outer surface corresponding to the number of projections of housing 12. The projections can be made to selectively insert into the corresponding recesses of the barrel to prevent the rotation of barrel 14. Numerous other modifications or changes can be applied to the locking means for preventing the rotation of the barrel 14.

The delivery valve holder 18 has to be removed from the fuel injection pump 10 during certain situations like during servicing or testing of the fuel injection pump 10. After testing or servicing, the delivery valve holder 18 has to be fixed again over the barrel 14.

When removing the delivery valve holder 18 from the fuel injection pump 10 or assembling it again to the fuel injection pump 10, the position of the barrel 14 gets disturbed by rotation.

A method of assembling and/or dismantling a fuel injection pump is explained as follows. Initially, rotation of a barrel 14 of a fuel injection pump 10 is locked with the help of a locking element. As explained earlier, the locking element may be an integral locking element 26 or a detachable locking element 32. The locking element 26 is inserted into the fuel supply passage 22 provided in the housing 12 of the fuel injection pump 10 and the fuel inlet port 20 of the barrel 14 to lock the rotation of the barrel 14, before adjusting the delivery valve holder 18. That is, rotation of the barrel 14 is locked before fixing the delivery valve holder 18 to the barrel 14 or removing it from the barrel 14.

The invention provides a simple and effective way to prevent the undesired rotation of the barrel at different situations such as during servicing of the fuel injection pump or during testing. Therefore, the position relationship between the helix of the plunger and the fuel inlet port of the barrel is not affected.

The locking element is detachedly inserted in the existing fuel supply passage and fuel inlet port. Therefore, no modification is required in the hardware.

The locking element can be selectively used, only when it necessary to prevent the rotation of barrel. Therefore, adjustment operation of barrel is not hindered.

It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiment and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

WE CLAIM:

1. A fuel injection pump (10) comprising a housing (12) with a barrel (14) ; a passage (20) in said barrel (14) ; characterized in that, said fuel injection pump (10) includes at least one locking element (26) detachedly inserted in said passage (20) to prevent the rotation of said barrel (14).

2. The fuel injection pump (10) of claim 1, wherein said passage (20) is a fuel inlet port (20) of said barrel (14).

3. The fuel injection pump (10) of claim 1 and 2, wherein said locking element (26) is detachedly inserted into said fuel inlet port (20) of said barrel (14) through a fuel supply passage (22) of said housing (12).

4. The fuel injection pump (10) of claim 3, wherein the locking element (26) has a thickness equal to inner diameter of said fuel supply passage (22).

5. The fuel injection pump (10) of claim 1 wherein the locking element (26) adapted to prevent the rotation of said barrel (14), when removing a delivery valve holder (18) from said fuel injection pump (10).

6. The fuel injection pump (10) of claim 1 wherein the locking element (26) adapted to prevent the rotation of said barrel (14), when attaching said delivery valve holder (18) to said fuel injection pump (10).

7. A locking means for a barrel (14) of a fuel injection pump (10), said means is adapted to prevent rotation of said barrel (14) during assembly and/or removal of a delivery valve holder (18).

8. The locking means of claim 7 is integrally provided in a housing (12) of said fuel injection pump (10).

9. The locking means of claim 8 is at least one projection formed on the housing (12) of said fuel injection pump (10), said at least one projection is inserted into at least one recess formed on said barrel (14).

10. The locking means of claim 7 is integrally provided in said barrel (14).

11. The locking means of claim 10 is at least one projection (32) formed on the outer surface of the barrel (14), said at least one projection (32) is inserted in to at least one recess (34) formed on inner surface of said housing (12).

12. A method for assembling and/or dismantling a fuel injection pump (10), said method comprising:

locking rotation of a barrel (14) of said fuel injection pump (10) by a locking element (26) while adjusting a delivery valve holder (18).