Patent Application
20100012093
The present invention relates to fuel injection systems of internal combustion engines; more particularly to fuel rail assemblies for supplying highly pressurized fuel to fuel injectors for direct injection into engine cylinders; and most particularly, to an apparatus and method for coupling a fuel injector for gasoline direct injection to a fuel rail.
Fuel rails for supplying fuel to fuel injectors of internal combustion engines are well known. A fuel rail assembly, also referred to herein simply as a fuel rail, is essentially an elongated tubular fuel manifold connected at an inlet end to a fuel supply system and having a plurality of ports for mating in any of various arrangements with a plurality of fuel injectors to be supplied. Typically, a fuel rail assembly includes a plurality of fuel injector sockets in communication with a manifold supply tube, the injectors being inserted into the sockets.
Fuel injection arrangements may be divided generally into multi-port fuel injection (MPFI), wherein fuel is injected into a runner of an air intake manifold ahead of a cylinder intake valve, and direct injection (DI), wherein fuel is injected directly into the combustion chamber of an engine cylinder, typically during or at the end of the compression stroke of the piston.
A DI fuel rail assembly must sustain significantly higher fuel pressures than a MPFI fuel rail assembly to assure proper injection of fuel into a cylinder having a compressed charge during the compression stroke.
Typical, DI fuel systems employ fuel injectors that are mechanically supported on the engine's cylinder head and are, therefore, referred to as non-hanging injectors. An MPFI fuel system, on the otherhand, employs injectors that are mechanically coupled to both the fuel rail and the cylinder head. Current DI technology developments may include a hanging injector system that suspends injectors from the fuel rail via a mechanical coupling, to eliminate metal-to-metal contact between the injector and the cylinder head. Such hanging injectors are highly desirable, whether in a DI or MPFI system, to reduce engine generated noise.
What is needed in the art is a fuel injector to fuel rail connection that is able to mechanically support loads originating from relatively high fuel pressures and from combustion pressure of direct injection fuel injection systems.
It is a principal object of the present invention to provide a high-pressure fuel injector coupling that easily connects a DI fuel injector to a fuel rail and that is able to manage relatively high separating loads between the fuel rail and the fuel injector due to relatively high DI fuel pressure levels.
Briefly described, a fuel injector coupling includes a retainer clip and a collar, which, when paired together, enable a simple, secure, and coincident keyed fuel injector-to-fuel rail connection that is able to withstand separating loads originating from the relatively high fuel pressure of a direct injection fuel system of an internal combustion engine.
In one aspect of the invention, the shape of the retainer clip permits fuel injector retention to a fully-annular flange of an injector socket, which is highly desirable since an annular flange is easier to machine than other geometrical shapes. The retainer clip is further shaped to provide ease of assembly and disassembly. The retainer clip includes convex windows to target load distribution upon the socket flange and the collar when assembled.
In another aspect of the invention, anti-rotation and retention features for the collar are integrated into the over mold of the injector. Such anti-rotation features are preferably designed to retain the collar in position until fuel rail assembly.
In still another aspect of the invention, coincident keyed features are integrated in the flange of the injector socket and in the collar to facilitate correct alignment of the injector relative to the fuel rail.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
Referring to
Injector socket 120 may include a cylindrical body 121 that is closed at one end and that is open at an opposite end 122 for receiving fuel injector 130. Accordingly, injector socket 120 may have, but is not limited to, the shape of a cup as shown in
Fuel injector 130 includes an overmold 132 surrounding a fuel tube 136. Overmold 132 is positioned such that a fuel inlet section 138 of fuel tube 136 extends beyond an upper end 134 of overmold 132 for assembly into injector socket 120. Fuel tube 136 includes a circumferential groove 142 that is positioned adjacent to the upper end 134 of overmold 132 when assembled. An anti-rotation feature 140 is integrated into overmold 132 and extends upper end 134 axially. Anti-rotation feature 140 may further extend the general outer circumference of overmold 132 radially. Anti-rotation feature 140 is preferably axially aligned with groove 142 of fuel tube 136 for mating with coupling 150. While fuel injector 130 is illustrated as a fuel injector for gasoline direct injection, it may be replaced by any other type fuel injector.
Coupling 150 includes a retainer clip 152 and a collar 154. Retainer clip 152 paired with collar 154 enable mechanical retention of fuel injector 130 to socket 120 even under relatively high separating loads. No additional support, for example, by the cylinder head of the internal combustion engine is needed. Accordingly, fuel injector 130 is suspended from fuel rail assembly 110 via mechanical coupling 150 such that no hard, metal-to metal contact need to exist between fuel injector 130 and the cylinder head. Retainer clip 152 may be shaped as a C-clip that partially encloses flange 124 and collar 154 and that engages with a circumferential contour of flange 124 and collar 154 when assembled.
Collar 154 has a generally circular shape and includes a coincident keyed feature 156 that is indexed to slot 158. Keyed feature 158 may be radially aligned with a slot 158. Coincident keyed feature 156 may extend outwards from the outer circumferential contour of collar 154 and may be formed, for example, as a tab. Slot 158 extends into collar 154 from the circumferential contour such that slot 158 is open at the circumferential contour of collar 154. Collar 154 is assembled to fuel injector 130 such that slot 158 mates with groove 142 integrated into fuel tube 138 and anti-rotation feature 140 integrated into overmold 132. Collar 154 may be pre-assembled to fuel injector 130 prior to shipping and prior to assembly of fuel injector 130 to fuel rail assembly 110. Collar 154 may be held in place by anti-rotation feature 140 integral with overmold 132, for example by an interference fit.
Retainer clip 152 includes a generally straight or slightly bent center section 162 and two end sections 164 curving away from center section 162 at opposite sides; all three sections forming a c-shaped cross-section. Center section 162 includes a window 166 designed for receiving coincident keyed features 128 and 156 of flange 124 and of collar 154, respectively. Each of the two end sections 164 includes a window 168 for receiving flange 124 of injector socket 120. In one aspect of the invention, at least the upper and the lower side of each of the windows 166 and 168 is curved to target even load distribution upon the load bearing socket flange 124 when assembled. A curved shape of windows 166 and 168 without sharp corners enables an improved management of loads, for example, by avoiding point loads. The sides, all four or at least the upper and the lower side, of each of the windows 166 and 168 have preferably a convex shape to distribute loads originating from separation forces acting between fuel injector 130 and fuel rail assembly 110 due to high operating fuel pressures. The distant tip of each end section 164 may be formed to curve radially outwards for ease of assembly and disassembly.
Retainer clip 152 and collar 154 may be stamped sheet metal parts and may be formed from a non-resilient cold-formable material that may be plated for corrosion protection. For example, a high carbon-steel with zinc-nickel plating applied may be used.
Referring to
As can be seen in
By providing coupling 150, relatively high fuel pressure loads causing separating forces between fuel rail assembly 110 and fuel injector 130 can be managed and a hanging fuel injector system 100 can be realized, where metallic contact between fuel injector 130 and a cylinder head is avoided. By minimizing a hard metal-to metal contact between the fuel injector and engine, operational noise and wear are reduced.
While coupling 150 may be especially useful for applications in fuel injection systems for direct injection, applications in fuel injection systems for port injection may be possible.
While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.
