1. Field of the Invention
The present invention relates to a direct spray fuel injector, and more particularly, a direct spray fuel injector that is capable of efficiently suppressing and preventing bounce generated in a valve needle of a bundle of opening/closing valves when a spray hole of an injector for injecting a fuel under a high pressure is closed due to the bundle of opening/closing valves that opens and closes the spray hole of the injector.
2. Description of the Related Art
In general, most direct spray fuel injectors that directly inject a fuel into a combustion chamber of an engine recently operate and are controlled in an electronic manner. A representative example thereof may include an injector having an opening/closing valve structure marked by reference numeral 101 of FIG. 1.
The injector 101 includes a bundle of opening/closing valves 110 including a valve needle 105 that directly opens and closes a spray hole 113, an electromagnetic coil 107 that pulls the valve needle 105 when the spray hole 113 is opened, an armature 109 that pulls the valve needle 105 by gravity of the electromagnetic coil 107, and a pressurizing spring 111 that elastically pressurizes the valve needle 105 against the spray hole 113, as illustrated in FIG. 1.
Thus, the injector 101 according to the relate art closes the spray hole 113 due to a valve ball 125 when the valve needle 105 is pressurized toward the spray hole 113 together with a stop ring 115 pressurized by an elastic force of the pressurizing spring 111 in normal times when no injection operation is performed, as illustrated in FIGS. 1 and 2.
However, when the injector 101 operates so as to inject the fuel under the high pressure, first, the electromagnetic coil 107 of the bundle of opening/closing valves 110 is excited. Thus, the armature 109 is pulled by a magnetic force of the electromagnetic coil 107, compresses a buffer spring 120 against a stop sleeve 117, is lifted upwardly in the drawing and thus contacts the stop ring 115.
The armature 109 pulled by the electromagnetic coil 107 even after contacting the stop ring 115 compresses the pressurizing spring 111 through the stop ring 115 and is lifted, as illustrated in FIG. 3. Thus, the valve needle 105 is lifted together with the armature 109 and opens the spray hole 113 such that a high-pressure fuel filled in a housing 103 can be injected into the combustion chamber.
Then, when injection of the injector 101 is completed, in contrast, the electromagnetic coil 107 is demagnetized and thus gravity of the electromagnetic coil 107 that pulls the armature 109 disappears. Thus, the valve needle 105 intends to return to a normal state illustrated in FIG. 2 and to close the spray hole 113. However, the valve needle 105 is bounced due to an elastic repulsive force generated when the valve ball 125 and a valve seat around the spray hole 113 contact each other or a high spray pressure in the spray hole 113 and is again lifted upwardly in the drawing, as illustrated in FIG. 4. This is usually referred to as ‘bouncing’ of the valve needle 105. Further bounce of the valve needle 105 lifted in this way is suppressed and prevented when the stop sleeve 117 is pressurized downward by the armature 109 that descends downward in the drawing due to a restorative force of the buffer spring 120.
In this way, in the injector 101 according to the related art, the bundle of opening/closing valves 110 suppresses and prevents the bounce of the valve needle 105. Thus, a spring holder 118 that supports the buffer spring 120 needs to be additionally disposed at an opposite side to a side in which the stop sleeve 117 is formed, so as to elastically support the armature 109 due to the buffer spring 120. Also, the spring holder 118 needs to be fixed to a bottom surface of the armature 109 by welding. Due to the buffer spring 120 and the spring holder 118, an assembling structure of the injector 101 according to the related art is complicated, and the number of components required for the injector 101 according to the related art increases. Thus, manufacturing efficiency or economic feasibility of the injector 101 according to the related art is lowered.