US3074652A

US3074652A - Fuel injection system

Info

Publication number: US3074652A
Application number: US110505A
Authority: US
Inventors: James F Armstrong
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1959-03-02
Filing date: 1961-05-16
Publication date: 1963-01-22
Anticipated expiration: 1980-01-22
Also published as: DE1197686B; GB938429A; GB938430A

Description

J. F. ARMSTRONG 3,074,652

FUEL INJECTION SYSTEM Jan. 22, 1963 Original. Filed March 2, 1959 FIG.I.

- mmvroa. JAMES FRED ARMSTRONG AGENT 3,074,652 Patented Jan. 22, 1963 ice 1 Claim. (Cl. 239-533) This invention relates to fuel injection systems for internal combustion engines, and more particularly to continuous flow systems of this class adapted for port injection, in which the fuel is pressurized, measured under pressure in accordance with engine requirements, and distributed under pressure to points adjacent the intake valves of the several cylinders or combustion chambers of the engine.

An object of the invention is the provision of an improved fuel injection nozzle construction, adapted for tightly sealing against leakage of fuel when closed, having a long life, and adapted to prevent the formation of droplets at a low rate of fuel flow (as when the engine is idling), and which is economical to manufacture.

In the accompanying drawings,

FIG. 1 is a plan view of an engine intake manifold, showing an arrangement of fuel injection nozzles.

FIG. 2 is a vertical section taken on line 2-2 of FIG. 1;

FIG. 3 is an enlarged vertical section of a nozzle in accordance with the invention and taken on line 33 of FIG. 1;

PEG. 4 is a greatly enlarged fragment of FIG. 3.

This application is a division of my application Serial Number 796,605, filed March 2, 1959, Patent No. 2,985,160.

As appears in FIG. 1, the fuel injector nozzles N are clustered in groups of two, so that, as a matter of practice, there are four nozzle clusters on the intake manifold M of the engine. As shown, each nozzle cluster comprises a body 131 (FIG. 3) formed to provide two shallow circular recesses 133 located side-by-side. Only one of these recesses appears in FIG. 3. A diaphragm 135 is clamped on the body by a head 137. This head is similarly formed to provide two shallow circular recesses 139 located side-by-side, which mate with recesses 133. Again, only one of these recesses 139 appears in FIG. 3. As to each nozzle N, recess 133 constitutes a charging fuel chamber and recess 139 constitutes a datum pressure chamber. The head 137 has an internally recessed rib 141 extending lengthwise thereof. This provides a passage 143 connecting the two datum pressure chambers of the cluster. Fuel connections may be made between the ends of these ribs to provide for the interconnection of the datum pressure chambers of all the nozzles N in the system. FIG. 1 shows interconnections at 145 between the forward and rearward clusters of each bank of four cylinders of the engine. The body 131 and head 137 are formed with bolt holes 147 for the reception of bolts for attaching them to the manifold M.

For each of the two nozzles N in a cluster, the base 131 of the cluster has an outwardly (downwardly) projecting tubular boss 14-9 coaxial with the recesses or

chambers

133, 139. The hole through this boss is enlarged at its inner end providing a recess 151 and an inwardly facing annular shoulder 153. Each nozzle N comprises a nozzle tube 155 threaded in the hole in the boss and projecting out (downward) from the boss. The nozzle tube has a head 157 at its inner (upper) end received in the recess 151 and seating against shoulder 153 for sealing purposes. Fixed in the outer (lower) end of the nozzle tube is a combination nozzle tip and valve seat member 159. This comprises a short tube having an annular external flange 161 which is press fitted into the inturned flange 163 at the outer (lower) end of the nozzle tube 155. The outer end of tip 159 is cut 011 at an angle as indicated at 165. The inner end portion of the tip 159 extends inward from flange 161 and provides a needle seat 167.

Each nozzle N includes the needle 27 having its inner (upper) end attached to the diaphragm 135, the needle extending slidably in the nozzle tube 155. The diameter of the needle is less than the internal diameter of the nozzle tube, to provide an annular space around the needle for flow of fuel through the tube to tip 159, and the needle is held centered in the tube by upper and lower radial projections 169 on the needle which slide on the internal surface of the nozzle tube. At its outer (lower) end, the needle has an enlarged portion 171. This portion has a conically concave face 173 at its outer end. It also has an axial passage 175 leading inward from the face and a passage 177 extending radially outward from the upper end of passage 175. Seated against face 173 is a piece of wire mesh 179, and seated against the wire mesh is a disk 181 of fuel-resistant rubber or the like.

The wire mesh 179 and rubber disk 181 are held against the face 173 by a cap 183 press fitted on the needle enlargement 171. The cap has an opening 185 for receiving the inner end portion 167 of nozzle tip 159. The cap terminates short of the radial passage 177, this passage and passage 175 being provided to vent air from under the disk 181 in the assembly of the wire mesh, disk and cap on the needle enlargement 171. The rubber disk 181 is initially a flat disk held in a bowed condition under compression against the face 173 by the cap 183, which places the lower working surface under compression to constitute a resilient tip for the needle engageable with the inner end 167 of the nozzle tip (which constitutes a seat for the needle) to provide a tight seal to prevent leakage when the needle is closed. The rubber face of the valve, being compressed, resists the shearing forces of seat engagement. The screen is used to provide for some slight swelling of the rubber composition between the interstices thereof. With the arrangement shown, when the needle is retracted and the rubber disk is clear of the seat 167, fuel flows upward around the seat 167, and thence around into the nozzle tip and down and out of the nozzle tip. This tends to avoid the formation of droplets at low rates of flow as during engine idling which would cause engine idle roughness.

As to each nozzle N, the needle 27 is biased downward by a spring 187 toward its closed position wherein the rubber disk 181 at the lower end of the needle engages the needle seat 167. For each nozzle, there is a passage 189 through the base and the head communicating with the lower recess or chamber 133. To this passage is connected the respective fuel delivery line 25. Accordingly, the needle 27 is subject to the downward force of spring 187 and datum pressure in recess or chamber 139 tending to drive it downward and close it, and an upward force due to charging fuel pressure in the lower recess or chamber 133 tending to drive it upward and open it. The charging pressure being sufficient to overcome the force of the spring 187 and the datum pressure, diaphragm 135 is moved upward to unseat the needle 27 from needle seat 167 for flow of fuel from chamber 133 out of the nozzle. Upon an increase in datum pressure, diaphragm 135 flexes downward to move the needle 27 closer to its seat 167, thereby to increase the back pressure in the nozzle charging fuel chamber 133, and vice versa.

I claim:

A nozzle for a fuel injection system, said nozzle comprising a housing, a diaphragm within said housing and forming therewith opposed expansible chambers, a tube having one end attached to said housing and extending from one of said chambers, a needle valve slidably mounted within said tube and attached at one end to said diaphragm, a nozzle tip at the other end of said tube having a tubular portion extending inwardly within said tube and forming avalve seat, a resilient member fixed t0 the other end of said needle valve adjacent to said valve seat, said resilient member being formed with a concave surface facing said valve seat, means fixed to said needle valve and retaining said resilient member with said concave surface under compression, said other needle valve end formed with a concave face, said retaining means holding said resilient member against said concave face, and a wire mesh between said resilient member and said concave face, said other needle valve end formed with an air vent passage extending from said concave 5 face into said tube.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,255,203 Wiegand Sept. 9, 1941 2,857,203 Korte Oct. 21, 1958 2,904,264 Klaber Sept. 15, 1959 2,957,631 Armstrong Oct. 25, 1960