Abstract A precision fuel injector having an inwardly opening pressure operated valve positioned in a bore forming a valve chamber and guided for reciprocal movement to open and close the valve wherein a threaded stepped cylindrical valve guide sleeve at the end of the valve chamber opposite the valve tip mounts the valve and cooperates with a mating portion of the bore to form an annulus filled with an initially flowable settable sealant. The sealant is pressurized during assembly of the guide sleeve and is forced into the clearance between the threads of the guide and the threads of the bore on both sides of the annulus to increase the length of the seal and to lock the guide sleeve in place. The blind end of the guide sleeve bottoms against a shoulder in the bore to establish a predetermined minimum cross-section of the annulus to minimize the possibility of fracture of the sealant ring therein due to differential expansion, and a pilot extending from the end of the guide sleeve and closely fitted within the surrounding bore protects the sealant against corrosion by the repetitive high impact hydraulic forces within the valve chamber.
In a fuel injector, a tubular body having a valve chamber, a valve guide mounting a pressure operable valve disposed in the valve chamber and a spring biasing the valve toward a valve seat having a discharge orifice, the improvement wherein the valve guide is a generally cylindrical sleeve having an end portion and a pair of axially displaced cylindrically shaped threaded outer surface portions separated by a step, and the portion of the valve chamber remote from the valve seat is provided with a bore having a pair of stepped surface portions which cooperate with the stepped surface portions of said sleeve to form an annular therebetween when the end portion of the guide sleeve bottoms on a mating shoulder provided by the bore to guard against the entry of sealant into the valve chamber, each of said stepped surface portions of said tubular body being threaded and respectively engaging one of the stepped threaded portions of said sleeve, and an initially flowable settable sealant disposed in said annulus to be entrapped and compressed therein during assembly as the guide sleeve is assembled in the injector to form a void-free ring of sealant filling the annulus and to force the sealant into the clearances between the threads in both directions from the annulus, the threads of the stepped surfaces of said valve guide and said tubular body being formed on the same helix but having different pitch diameters.
Claim 2
Dependent Claim
239 words
In a fuel injector, a tubular body having a valve chamber, a valve guide mounting a pressure operable valve disposed in the valve chamber and a spring biasing the valve toward a valve seat having a discharge orifice, the improvement wherein the valve guide is a generally cylindrical sleeve having an end portion and a pair of axially displaced cylindrically shaped threaded outer surface portions separated by a step, and the portion of the valve chamber remote from the valve seat is provided with a bore having a pair of stepped surface portions which cooperate with the stepped surface portions of said sleeve to form an annular therebetween when the end portion of the guide sleeve bottoms on a mating shoulder provided by the bore to guard against the entry of sealant into the valve chamber, each of said stepped surface portions of said tubular body being threaded and respectively engaging one of the stepped threaded portions of said sleeve, and an initially flowable settable sealant disposed in said annulus to be entrapped and compressed therein during assembly as the guide sleeve is assembled in the injector to form a void-free ring of sealant filling the annulus and to force the sealant into the clearances between the threads in both directions from the annulus, the threads of the stepped surfaces of said valve guide and said tubular body being formed on the same helix but having different pitch diameters.
Claim 3
Dependent Claim
32 words
An injector as recited in claim 1 wherein a groove is provided between the stepped threaded outer surface portions of the guide sleeve to axially space said threads of different pitch diameters.
Claim 4
Dependent Claim
29 words
An injector as recited in claim 1 including throttling means for throttling the flow of fuel from said valve chamber toward said sealant to protect the sealant against corrosion.
Claim 5
Dependent Claim
31 words
An injector as recited in claim 3 wherein said throttling means comprises a pilot formed on the end portion of on said valve guide which is closely received in said bore.
Claim 6
Dependent Claim
19 words
The injector of claim 4 including an annulus between said pilot and the mating threads of said stepped surfaces.