Patent ID: 7309032
Filing Date: 2007-12-18
Classification: F02M,F16K

Abstract:
1. A dosing device for dosing a fluid under pressure being dosed, comprising: a housing with a dosing aperture which can be controlled by displacement of a valve needle, an electromechanical actuator, whose length can be changed in the axial direction, which is located inside a working chamber of the housing, and whose two end faces are connected one to the valve needle and the other to an axially movable hydraulic piston, a hydraulic chamber hydraulically connected in a throttled manner to the working chamber by means of a first fit between the hydraulic piston and the housing, with the first fit being embodied in such a way that the hydraulic piston will retain its position relative to the housing if there is a rapid change in the length of the actuator, wherein the working chamber and the hydraulic chamber can be filled with a working fluid, the working chamber is divided by a hermetically tight separating membrane into an actuator chamber containing the actuator and a fluid chamber, the fluid chamber can be filled under pressure with the fluid being dosed, while the actuator chamber and the hydraulic chamber are filled with a hydraulic fluid as the working fluid, and wherein a base pressure can be produced in the hydraulic fluid by means of the pressure of the fluid being dosed, said pressure being transmitted through the separating membrane, the valve needle is routed through two narrow needle ducts axially in the housing in the area between the fluid chamber and the dosing aperture, the valve needle has flattened sections in the area of the needle duct on the side of the dosing aperture so that the fluid being dosed, which is supplied from a fluid feed, can reach the dosing aperture unimpeded, the needle duct on the fluid chamber side is embodied so narrowly as to allow either no hydraulic link or only a highly throttling hydraulic link between the needle duct on the side of the dosing aperture and the fluid chamber, and the fluid being dosed can be supplied for the purpose of pressure-filling the fluid chamber via a branch from the fluid feed to said fluid chamber.