| 摘要 |
A directly actuated injection valve comprises a hollow valve housing (102), a valve needle (119) disposed within the hollow interior, a needle spring (116), an actuator assembly, and a hydraulic link assembly. Th e actuator assembly generates an opening force that acts against the needle spring (116) to open the valve. The hydraulic link assembly is interposed between t he valve needle (114) and the needle spring (116) and the actuator assembly. Th e hydraulic link assembly transmits respective closing and opening forces to t he valve needle (114). The hydraulic link preferably comprises a piston (114b) disposed within a cylinder (160) that is filled with a hydraulic fluid. The opening and closing forces are transmitted through a thickness of the hydraulic flui d that is trapped between the planar surfaces of the piston (114b) and the hea d (162) and base of the hydraulic cylinder. In the preferred embodiment, the thickness of the hydraulic fluid trapped between the piston (114b) and cylinder head (162) or base is automatically adjustable in response to changes in the dimensional relationship between components of the injection valve to mainta in a desired valve needle lift when the actuator assembly is activated. When the actuator assembly comprises a magnetostrictive or piezoelectric member (130), the movements of the valve needle (114) can be controlled by the application of a shaped control pulse or waveform to improve the speed of th e opening and closing motion of the valve needle (114), and to reduce the impa ct of the valve needle on the valve seat upon closing. |
