Patent ID: 8746213
Filing Date: 2014-06-10
Classification: F02M

Abstract:
1. A fluid injection device comprising: a nozzle having a length on an axis and comprising an injection orifice and a seat, the nozzle being, at the opposite end on the axis, connected to a first body; a needle having, on the axis, a length and a first end defining a valve element, in a zone of contact with the seat, the needle being, at the opposite end on this axis, connected to a second body mounted so as to move axially in the first body; means for vibrating to vibrate with a setpoint period τ the nozzle, thereby ensuring between the first end and the nozzle, on the axis, a relative movement suitable for opening and closing the valve element alternatively, the nozzle with the first body and the needle with the second body respectively forming a first and a second media for propagating acoustic waves, each medium having a linear acoustic impedance defined by following equation: I=Σ*ρ*c, where Σ is a surface of a section of the medium perpendicular to the axis, ρ is a density of the medium, c is a velocity of the sound in the medium; at least one zone of linear acoustic impedance breakage existing at a distance from the zone of contact of the seat with the first end along the nozzle or the first body, and at least one other zone of linear acoustic impedance breakage existing at a distance from the zone of contact of the first end with the seat along the needle or the second body; and the zone and other zone of linear acoustic impedance breakage each being first in the order from the zone of contact between the first end of the needle and the seat, in a direction of propagation of the acoustic waves that is oriented respectively toward the first body and second body; wherein a first distance between the zone of contact between the seat and the first end, and the first zone of linear acoustic impedance breakage along the nozzle or the first body, is such that the propagation time of the acoustic waves initiated by the vibration means and traveling over this first distance satisfies following equation: T wherein a second distance between the zone of contact between the first end and the seat, and the first zone of linear acoustic impedance breakage along the needle or the second body, is such that the propagation time of the acoustic waves initiated by the vibration means and traveling over this second distance satisfies following equation: T