Electromagnetically operated fuel injection valve

Claim 1

A fuel injection valve adapted to be suitably mounted on an internal combustion engine so as to be communicated with an intake passage of a combustion chamber thereof comprising: a. a tubular valve body having a central stepped-bore therethrough along a valve body axis and comprising hub means, stop means, and axially separated first and second hold-in means, i. said hub means separating said stepped bore into a coil and inlet means cavity and an actuator means cavity and comprising a stop means positioning surface and a first circumferential flux path surface defining one side of a two-sided radial air gap, and ii. said stop means positioned axially against said stop means positioning surface of said hub means and extending radially inward therefrom; b. tubular inlet means secured in said coil and inlet means cavity by one of said valve body hold-in means, said tubular inlet means comprising an outwardly extending flange portion intermediate an inlet tube portion and an outlet tube portion, i. said inlet tube portion adapted to be communicated with a source of pressurized fuel, ii. said inlet tube portion and said outlet tube portion having central inlet fuel passage therethrough along said valve body axis, and iii. said outlet tube portion terminating in a first transverse flux path surface defining one side of a two sided axial air gap; c. actuator housing means secured in said actuator cavity of said valve body by the other of valve body said hold-in means and having a central stepped-bore extending therethrough along said valve body axis and separated by a seat into a fuel outlet bore portion and an actuator bore portion by a valve seat for seating a valve seat and metering means, i. said fuel outlet bore portion comprising fuel outlet holding means; ii. said actuator bore portion having shoulder abutment means abutting said valve body stops means; and iii. said valve seat and metering means having an inlet side and an outlet side and comprising a metering orifice having an inlet end and an outlet end, an outlet surface diverging towards said outlet side from said orifice outlet end and at least two contiguous inlet surfaces converging from said inlet side towards the inlet end, one of said converging inlet surfaces comprising a coined partly spherical valve guide surface defining at its intersection with the other contiguous inlet surface a circular valve seat edge; d. fuel outlet means secured in said outlet bore portion against said outlet side by said fuel outlet hold-in means and comprising a fuel breakup disc means having a plurality of narrow arcuate slots therethrough, each slot having a radial width of not greater than 0.15 mm and an arcuate length not less than twice said radial width and the number and length of said slots selected to effect a total slot area comprising at least 150 percent of the area of said metering orifice; e. actuator means loosely supported relative to said actuator bore portion of said actuator housing means and adapted to reciprocate axially therein along said valve body axis between an open position and a closed position, said actuator means comprising armature means and valve head and means, i. said armature means comprising a guide element, an armature element and an abutment element, said abutment element adapted to abut against said valve body stop means to there establish said open position, said armature section having a second circumferential flux path surface and a second transverse flux path surface respectively defining the other sides of said circumferential and axial air gaps, said guide element having an arcuate peripheral surface loosely engaging said actuator bore portion so as to center said actuator means to prevent said widths of said first and second air gaps from being less than first and second predetermined air gaps, and said guide element and said armature element having a flow smoothing fuel passage means therethrough communicating with said central inlet passage of said inlet means, and ii. said valve head and stem means having a free end terminated in a partly spherical valve head, a fixed end fixed centrally in said armature element, and a stem length intermediate said free end and said fixed end telescoped by a portion of said central flow smoothing passage means and having a radial clearance therein sufficient to permit flex therein as said partly spherical valve head is guided by said valve guide surface to seat on circular valve seat edge and there establish said closed position of said actuator means; and iii. spring means positioned between said armature element and said tubular inlet means to normally bias said actuator means in a direction from said inlet means toward said valve seat and orifice means; and iv. electromagnetic coil means positioned in said coil and inlet means cavity intermediate said valve body hub means and said inlet flange portion, said coil means adapted to be energized to establish a magneto-motive force on said armature element sufficient to move said actuator means from said closed position to said open position; whereby with said coil means energized when said inlet connector portion is communicated with said source of fuel at a predetermined pressure and when said fuel injector valve is also communicated with said combustion chamber intake passage, said central inlet fuel passage of said inlet means cooperates with said central passage of said armature means to provide a substantially laminar fuel flow to said valve seat edge, said laminar fuel flow permitting repeatable precise metering in accordance with both said metering orifice area and substantially all of said predetermined pressure, said thin arcuate slots and the remainder of said predetermined pressure cooperating to break up said fuel into uniformly small droplets.