Clamping element for a fuel injection valve and fuel injection system

#The present invention relates to a clamping element and a fuel injection system.

#A clamping element in the form of a hold-down element is referred to in Japanese Published Patent Application No. 08-312503. The hold-down element holds down a fuel injector against a relatively high combustion pressure prevailing in the combustion chamber of the internal combustion engine. The hold-down element engages with a collar of the fuel injector at two circumferentially opposite locations, the collar resting with its lower side on the upper side of the cylinder head, so that the fuel injector is held down. The hold-down element is pulled on to the cylinder head by a clamping screw.

#It is believed that the hold-down element referred to in Japanese Published Patent Application No. 08-312503 has the disadvantage that it is difficult to access the clamping screw if a fuel distribution line has already been fitted. If the fuel distribution line is not fitted until after the hold-down elements have been fitted and after they have been pre-tensioned to the defined retention force, the fuel injectors may no longer be moved or may only be moved if considerable force is applied, and tolerances at the connection points to the fuel distribution line, which in the case of high-pressure injection systems is rigid, may not be modified. Furthermore, a tight connection may only be achieved with difficulty or not at all. If the clamping screws are not tightened until after the fuel distribution line has been fitted, it may be difficult to access the clamping screws.

#FIG. 1 shows a clamping element via which a fuel injector is clamped into a mounting hole.

#FIG. 2 shows an exemplary clamping element according to the present invention installed between a fuel distribution line and a fuel injector.

#FIG. 3 is a sectional view of the exemplary clamping element according to the present invention shown in FIG. 2 with fuel a distribution line.

#FIG. 1 shows a clamping element. The clamping element is in the form of a hold-down element 1, which holds a fuel injector 2 in a mounting hole 3. Fuel injector 2 is connected to a rigid fuel distribution line 4, for fuel injectors that inject fuel at high pressure into the combustion chamber. Hold-down element 2 has a contact piece 5, which rests on a cylinder head 6 (shown here in section view, and only partly shown) and has an attachment element that is embodied as screw 7. Screw 7 penetrates a lever arm 8 of hold-down element 1 and is screwed into a threaded hole 9 of cylinder head 6.

#Lever arm 8 divides in the shape of a fork around fuel injector 2. Fuel injector 2 has a step 10, on whose radial surface pressure mushrooms 11, which are formed on the ends of the fork-shaped section of lever arm 8 of hold-down element 1, rest. If it is rotated deeper into threaded hole 9, screw 7 pulls lever arm 8, which rests against cylinder head 6 via contact piece 5, toward cylinder head 6 via a washer 12, which allows angle compensation via a spherical surface 13. As a result, at the fork-shaped end of lever arm 8 a clamping force is exerted on fuel injector 2 in the direction of mounting hole 3 via pressure mushrooms 11 (only one can be seen in the chosen view in the drawing) at two points of step 10 that are located opposite one another on the circumference of fuel injector 2. This clamping force holds fuel injector 2 in mounting hole 3 against the combustion pressure in the combustion chamber (not shown).

#FIG. 1 also shows connector plug 14 for triggering fuel injector 2 and seal 15 opposite the combustion chamber. Fuel distribution line 4 is connected to fuel injector 2 via connector nozzle 14a.