INSERT OF FLUIDIC DIODE TYPE FOR ATTENUATING PRESSURE WAVES, AND COMMON RAIL EQUIPPED WITH SUCH INSERTS

摘要

The insert reduces the propagation of pressure waves in counterflow direction in a device for supplying the high pressure fuel in an injection system. The insert (50) is globally cylindrical with respect to a central axis (A), has front and rear faces (51,52), comprises an opening (127) around the central axis in the form of a channel in two parts (128,29) in the direction of fuel flow, and a bore of diameter (D') which is much larger than the diameter (d) of the second part (29) of the opening (127). The diameter of the opening in the first part (128) is continuously reducing downstream in the direction of the central axis in a manner which is slow with respect to the flow characteristics and avoids any sharp angles in particular at the points of joining different sections of the channel. The first part (128) of the opening (127) is generated by rotating a straight line segment at an angle (alpha) with respect to the central axis and around the axis, which is extended in the upstream direction by a circular arc with a first radius and a first centre of curvature, and extended in the downstream direction by a circular arc with a second radius and a second centre of curvature. The second circle is tangential to the generator of the second part (29) of the opening (127). The first radius and the second radius are larger or at least of the same order as the diameter (d) of the second part (29) of the opening (127). The first centre and second centre are on the same side of the straight line segment, or on the opposite sides of the straight line segment in another embodiment of the insert. The bore (53) is opened at the rear face (52) of the insert. The external surface (60) of the insert presents a slight conicity determined by an angle (beta) so that the diameter of the surface is slightly smaller at the level of the bottom wall (55) of the insert. The edge between the front face (51) and the exterior surface (60) is bevelled. The insert is made of hard steel. A common rail (claimed) designed as a part of a device for supplying the high pressure fuel comprises a pump and an injection system, input and injection mains, an input and at least one output equipped with the insert (claimed).