Method for making a through opening in a high-pressure fuel reservoir, and apparatus for performing the method

#1. Field of the Invention

#The invention relates to a method and an apparatus for making through openings in a high-pressure fuel reservoir.

#2. Description of the Prior Art

#Other features and advantages of the invention will be apparent from the description contained below, taken with the drawings, in which:

#FIG. 1 is a cross section through a high-pressure fuel reservoir with a connection stub and an introduced chucking device, before a bore for the through opening is made;

#FIG. 2 is a cross section through the high-pressure fuel reservoir of FIG. 1, after the bore has been made;

#In FIG. 1, a cross section is shown through a high-pressure fuel reservoir, which includes an elongated tubular metal jacket body 1, which for the sake of supplying fuel injection valves has formed-on connection stubs 3 produced for instance by forging. Naturally still other connection stubs 3 can also be provided, which serve to attach a high-pressure fuel pump or a pressure sensor. The interior of the high-pressure fuel reservoir is formed by a continuous recess 2, extending longitudinally of the jacket body 1 and preferably having a circular cross section. However, the cross section can take some other form instead, and for instance can be elliptical. The continuous recess 4 made in the jacket body 1 can be solidly closed on one face end. The other face end is open and can for instance be closed by a screwed-on pressure limiting valve, the attachment of the high-pressure fuel pump, a lid, or in some other way.

#As is also shown in FIG. 1, a chucking device is thrust into the continuous recess 2 from the open side of the high-pressure fuel reservoir. The chucking device includes a central chucking part 12 and two chucking jaws 10 and 11 of semicircular cross section. The chucking jaws can have some other cross-sectional shape instead, however. In the example shown here, the outside radius of the first chucking jaw 11 is adapted to the radius of curvature of the inner wall 4 of the continuous recess 2. The outside radius of the second chucking jaw 10 is designed to be somewhat less than the radius of curvature of the inner wall 4 of the continuous recess 2. As can also be seen, the region of the second chucking jaw 10 that is oriented toward the connection stub 3 is provided with a recess 6, into which a pressure part 13 is inserted. The face contour 14 of the pressure part 13 oriented toward the inner wall 4 is adapted precisely to the contour of the inner wall 4. In the exemplary embodiment shown here, the face contour 14 and the inner wall 4 accordingly have the same radius of curvature. Other recesses and other pressure parts are correspondingly provided on the other connection stubs of the jacket body 1. If not all the connection stubs protrude in the same direction from the jacket body 1, then the chucking device may need to be rotated in order to produce all the bores. The chucking jaws 10, 11, the chucking part 12 and the pressure parts 13 are made from metal. However, it is also conceivable to use some other suitable material. For instance, the pressure parts can also be made from a very hard plastic.

#The central chucking part 12 also has a wedge-shaped contour. By insertion of the chucking part 12, the first chucking jaw 11 and the pressure part 13 are pressed against diametrically opposed portions of the inner wall 4 of the continuous recess. As is shown in FIG. 2, to produce a through opening, a bore 5 in the nature of a blind bore is made in the connection stub 3 and the pressure part 13. Drilling is done to some distance into the pressure part 13 from outside through the connection stub 3 and the jacket body 1, using the drilling tool. Advantageously, drilling is done in such a way that the entire tip of the drilling tool enters into the pressure part 13. By means of the pressure part 13, the creation of a burr at the edge formed by the inner wall 4 and the bore 5 is avoided. The same procedure is employed for the other connection stubs. Then the drilling tool and the chucking device 10, 11, 12, 13 are removed. The connection stubs 3 can now be provided with a screw thread as well, onto which a high-pressure connecting line can be connected via a cone seal. After the chucking device has been removed, the insertion parts 13 can be replaced. Now the chucking device is once again ready for making further bores in the next high-pressure fuel reservoir to be machined.