| 摘要 |
<p>Injection valve for internal combustion engines, provided with a nozzle body (10) with injection holes (11, 12) for the fuel and two coaxial spring-loaded valve needles co-operating with separate injection holes. The external hollow needle (7) has radial bores (14) and the inner valve needle is designed as a control piston (13) of which the jacket, in the region of the openings of the radial bores (14) of the hollow needle (7), has control edges formed of an annular recess (15). Leading from the recess in the jacket of the control piston (13) are ducts, or preferably an axial bore (19), which extend to a seating (20), arranged on the control piston (13), of a valve-closing element (21) which co-operates with the control piston, such as for example a tapered element or ball. After a pre-determined travel of the control piston (13) the recess (15) forming the control edges causes a pressure drop and closure of the relevant injection holes (12), as a result of which a separation is achieved between the pre-injection and the main injection initiated by the raising of the hollow needle (7).</p> |
