Electromagnetic fuel injector

Claim 2

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including stationary pole means and an armature means operatively associated with the valve for controlling movement thereof, the armature means being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole means; the improvement wherein at least one of the opposed end surfaces of the pole means and of the armature means has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches whereby, during operation, the wear caused by impact or fluid cavitation at said surfaces will be substantially reduced so as to permit for the extended usage of the injector without effecting the original calibration of the injector.

Claim 3

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including stationary pole means and an armature means operatively associated with the valve for controlling movement thereof, the armature means being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole means; the improvement wherein at least the physically softer of one of the opposed end surfaces of the pole means and has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches whereby the hydraulic stiction between these surfaces is reduced so that during operation the wear at said surfaces will also be substantially reduced resulting in extended calibrated operational durability of the injector.

Claim 4

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including stationary pole means and an armature means operatively associated with the valve for controlling movement thereof, the armature means being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole means; the improvement wherein at least the physically softer of one of the opposed end surfaces of the pole means and has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches whereby the hydraulic stiction between these surfaces is reduced so that during operation the wear at said surfaces will also be substantially reduced resulting in extended calibrated operational durability of the injector.

Claim 5

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including a stationary pole piece, an armature movable axially in the bore relative to the pole piece operatively associated with the valve for controlling movement thereof, spring means positioned for normally biasing the armature in a direction away from the pole piece to effect engagement of the valve with the valve seat and a non-magnetic shim positioned between the working air gap surfaces of the pole piece and armature, the armature being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole piece; the improvement wherein the end surface of the pole piece adjacent to the armature has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches and the end surface of the armature is physically harder and smoother relative to the pole piece end surface so that the wear at said surfaces will be substantially reduced permitting extended usage of the injector without substantial adverse effects on the original calibration of the injector.

Claim 6

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including a stationary pole piece, an armature movable axially in the bore relative to the pole piece operatively associated with the valve for controlling movement thereof, spring means positioned for normally biasing the armature in a direction away from the pole piece to effect engagement of the valve with the valve seat and a non-magnetic shim positioned between the working air gap surfaces of the pole piece and armature, the armature being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole piece; the improvement wherein the end surface of the pole piece adjacent to the armature has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches and the end surface of the armature is physically harder and smoother relative to the pole piece end surface so that the wear at said surfaces will be substantially reduced permitting extended usage of the injector without substantial adverse effects on the original calibration of the injector.

Claim 7

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including stationary pole means and an armature operatively associated with the valve for controlling movement thereof, the armature being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole means; the improvement wherein a non-magnetic shim of physically softer material than the working air gap end surface of the armature is fixed to the pole means and wherein the exposed end surface of said shim has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches whereby, during operation, the wear caused by impact or fluid cavitation between said shim and the armature will be substantially reduced so as to permit for the extended usage of the injector without any substantial effect on the original calibration of the injector.

Claim 8

In an electromagnetic fuel injector of the type having a hollow tubular body with a stepped bore therethrough providing a fuel chamber therein intermediate its ends adapted to receive fuel, a fuel nozzle positioned in the stepped bore at one end of the body to define a spray tip at the one end and an annular valve seat encircling a discharge passage upstream of the spray tip in communication with the fuel chamber, a valve positioned in the stepped bore for movement into and out of engagement with the valve seat and a solenoid means including stationary pole means and an armature operatively associated with the valve for controlling movement thereof, the armature being movable axially in the bore and positioned so as to move into and out of engagement relative to one end of the pole means; the improvement wherein a non-magnetic shim of physically softer material than the working air gap end surface of the armature is fixed to the pole means and wherein the exposed end surface of said shim has a roughened surface texture with an average surface roughness rating value of the order of 16 to 32 microinches whereby, during operation, the wear caused by impact or fluid cavitation between said shim and the armature will be substantially reduced so as to permit for the extended usage of the injector without any substantial effect on the original calibration of the injector.