Abstract:
Bayonet lugs and bayonet slots are provided on a fuel injector and a fuel rail respectively to provide for the injector to be installed in a transverse through-hole in the fuel rail by circumferentially registering the lugs with the slots, inserting the injector into the through-hole to a predetermined depth established by an abutment stop which is sufficient to allow the lugs to pass through the slots, and then twisting the injector about its own axis to remove the lugs from their insertion registry with the slots and cause the injector to become axially captured and correctly indexed in the through-hole.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to internal combustion engine fuel systems and more specifically to the mounting of electrically operated fuel injectors on such fuel rails, especially bottom-feed fuel injectors. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     A bottom-feed electrically operated fuel injector is typically characterized by the fact that its fuel inlet is disposed proximal to its fuel outlet and distal to its electrical connector. For example, the fuel inlet may be disposed in the sidewall of the injector body while the fuel outlet is disposed at one axial end of the body and the electrical connector is disposed at the opposite axial end of the body. The typical mounting of such a fuel injector on a fuel rail comprises the fuel injector being disposed in a transverse through-hole in the rail such that: the injector&#39;s fuel inlet is in fluid communication with a main longitudinal fuel passage in the fuel rail; the fuel injector&#39;s body is sealed to the wall of the transverse through-hole on axially opposite sides of the injector&#39;s fuel inlet; the injector&#39;s electrical connector is disposed at one axial end of the transverse through-hole so as to be available for connection to a mating electrical connector that delivers operating current to the injector; and the injector&#39;s outlet is disposed at the opposite axial end of the through-hole for injecting fuel into the engine for entrainment with combustion air. 
     It is a typical practice to mount a bottom-feed fuel injector on a fuel rail by inserting the fuel injector, outlet end first, into the transverse through-hole in the fuel rail until the insertion is arrested by abutment with an abutment stop located a predetermined distance inside the through-hole. A cover, which may include an electrical connector for connecting to the electrical connector of the fuel injector, is then disposed over the proximal end of the injector and fastened to the fuel rail to capture the installed injector in the through-hole. Examples of known practices are evidenced by U.S. Pat. Nos. 4,475,486; and 4,844,036. An example of a clip attachment for a top-feed injector is shown by U.S. Pat. No. 4,475,516. 
     Circumferential orientation of a fuel injector within a transverse through-hole in a fuel rail may also be important. Such is usually the case where the injector is of the split-stream type. It is therefore desirable to provide a circumferential locator for assuring the proper circumferential orientation of a fuel injector in a transverse through-hole in a fuel rail. Examples are evidenced by certain commonly assigned co-pending applications that are known to the USPTO by virtue of their pendency. 
     The present invention relates to a novel mounting of an electrically operated fuel injector on a fuel rail which may be especially useful for certain engine applications. The invention comprises the inclusion of a keying means associated with one of the through-hole and the injector and a keyed means associated with the other of the through-hole and the injector. The keying means and keyed means are effective to permit the one to pass axially through the other during insertion of the fuel injector into the through-hole, provided that the fuel injector is properly circumferentially oriented to register the keyed means with the keying means, and to permit the fuel injector to be twisted about its own axis after having been fully inserted into the through-hole such that the keying means and the keyed means are removed from registry and are instead placed in an interference relationship preventing the fuel injector from being extracted from the through-hole. An abutment stop is also provided on the one of the keying means and keyed means that is associated with the through-hole for abutment with the fuel injector for the purpose of limiting the extent to which the fuel injector can be twisted once the fuel injector has been fully inserted into the through-hole, thus enabling the fuel injector to be properly circumferentially oriented within the through-hole. The disclosed embodiment of the invention comprises a pair of bayonet lugs on the injector body which constitute the keyed means and an annular disc which is mounted on the fuel rail in the through-hole and embodies a pair of bayonet slots which constitute the keying means. 
     Further details of the invention, along with advantages and benefits of the invention, will be seen in the ensuing description which is accompanied by drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time for carrying out the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an axial end view of a fuel injector mounted on a fuel rail in accordance with principles of the present invention. 
     FIG. 2 is a view, partly in cross section, through FIG. 1 in the direction of arrows 2--2. 
     FIG. 3 is a fragmentary cross section in the direction of arrows 3--3 in FIG. 1. 
     FIG. 4 is a fragmentary view in the same sense as FIG. 3, showing a modification. 
     FIG. 5 is a fragmentary view in the same sense as FIG. 1 showing a modification. 
     FIG. 6 is a fragmentary view in the same sense as FIG. 1 showing a modification. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 2, and 3 show a portion of a fuel rail assembly 10 containing several electrically operated fuel injectors 12 mounted on a fuel rail 14 at intervals along the fuel rail&#39;s length. Fuel rail 14 comprises several transverse through-holes 16, and there is one fuel injector 12 disposed in each through-hole 16. 
     Each through-hole 16 comprises a series of axially outwardly facing circular shoulders separated by radially inwardly facing circular sidewall sections. Thus, in the direction from its inner end to its outer end, each through-hole 16 comprises an inclined shoulder 18a between sidewall sections 20a, 20b, a chamfered shoulder 18b between sidewall sections 20b, 20c, and a shoulder 18c between sidewall sections 20c, 20d. A main longitudinal fuel passage 22 through fuel rail 14 intersects the sidewall section 20b of each through-hole 16 in a generally tangential manner. 
     Fuel injector 12 comprises a body 24 having a generally cylindrical shape. The fuel outlet 26 of the injector is at the axial end of body 24 that is disposed at the inner end of through-hole 16 while the electrical connector 28 of the injector is at the opposite axial end of body 24 and disposed exterior of the outer end of the through-hole. Connector 28 comprises two electrical terminal pins 30, 32 adapted for connection to mating receptacles in a mating connector (not shown) which delivers electric current for operating the fuel injector. The fuel inlet of the injector is provided by a circular groove 34 in the side of body 24 leading to one or more circular holes 36 extending into the interior of the injector. 
     FIGS. 1-3 illustrate the fuel injector in the fully installed position on the fuel rail. Circular O-ring seals 38, 40 are disposed on body 24 to provide radial sealing between the body and through-hole 16 on axially opposite sides of groove 34 so that fuel which passes into the interior of the injector from fuel passage 22 via groove 34 and hole(s) 36 does not leak out through through-hole 16. The O-ring seals 38, 40 are disposed around the outside of body 24 in respective circular grooves that open radially outwardly. 
     In accordance with principles of the invention, through-hole 16 is provided with a keying means 42, and injector 12 with a keyed means 44. The keying means 42 is in the form of an annular disc that is disposed in sidewall section 20d against shoulder 18c. The keyed means 44 comprises a pair of bayonet lugs, or keys, 46, 48 on diametrically opposite sides of that portion of body 24 that is axially co-extensive with sidewall section 20c. 
     A large portion of the disc of keying means 42 is flat and occupies a plane that is perpendicular to the axis of through-hole 16. This portion is designated by the numeral 50. The radially inner margin of portion 50 overhangs sidewall section 20c. The radially outer margin of the disc of keying means 42 is canted radially outwardly and axially away from shoulder 18d, and comprises a number of circumferentially spaced apart teeth 52. The radially outermost edges of these teeth are digging into sidewall section 20d to hold the disc of keying means 42 in assembly with fuel rail 14 in the manner described and illustrated. 
     The radially inner margin of portion 50 overhanging sidewall section 20c comprises diametrically opposite bayonet slots, or keyways, 54, 56, that interrupt the otherwise circular inner edge 57 of the disc of keying means 42, the latter keyway being somewhat larger than the former. Lugs 46, 48 are adapted for respective registry with keyways 54, 56 when the injector is twisted ninety degrees counterclockwise about its own axis from the position illustrated in FIG. 1. The lugs are sized slightly smaller than their respective keyways, so that when registered therewith, they will pass axially through the disc of keying means 42 to allow the injector to be extracted axially out of the through-hole while the disc remains securely in place in assembly with the fuel rail. 
     The fuel injector is assembled into the fuel rail in the opposite manner from which it was removed. Assembly is accomplished by aligning the injector&#39;s axis with the through-hole&#39;s axis, circumferentially registering lugs 46, 48 with keyways 54, 56, inserting the injector into the through-hole to pass the lugs through the disc of keying means 42 until the insertion is arrested by the abutment of a shoulder 24a of body 24 with shoulder 18b of through-hole 16, and then rotating the injector approximately ninety degrees clockwise about its own axis as viewed in FIG. 1 at which point the clockwisemost portion of lug 48 will be abutting a tab 58 extending down from the inner margin of the disc of keying means 42 at approximately the four o&#39;clock position of FIG. 1. The electrical connector (not shown) that delivers operating current to the fuel injector can then be mated with connector 28 of the fuel injector. 
     From consideration of FIG. 1 it can be appreciated that on account of the particular shape and location of the lugs and keyways, a polarization has been created whereby the fuel injector can be axially seated in the through-hole by initially disposing the fuel injector at only a single unique circumferential orientation relative to the through-hole. FIG. 1 shows that after the lugs have passed through the disc of keying means 42 and the injector has been twisted to move the lugs out of registry with the keyways, the lugs are axially captured between the inner overhanging margin of the disc and shoulder 18b. Twisting of the injector until lug 48 abuts tab 58 assures that the injector has been properly circumferentially oriented. Although not specifically shown in the drawings, a detent may be incorporated into the construction so that the attainment of the fully installed position may be tactilely sensed, and as an aid in preventing possible self-loosening of the installed injector. 
     FIG. 4 illustrates a modification wherein after the disc had been inserted into the through-hole, the rim of sidewall section 20d has been deformed (reference numeral 59) over the outer margin of the disc to axially capture the disc and thus assure that the disc does not shift from its intended position on the fuel rail. Such deformation may occur locally at selected circumferential locations around the rim, or it may be done around the entire circumference. 
     FIG. 5 illustrates a modification wherein a keying means 60 and a keyed means 62 are provided on the disc and the through-hole to assure proper circumferential orientation of the disc with respect to the fuel rail&#39;s through-hole. 
     FIG. 6 illustrates a modification wherein a tab 64 extends down from the inner margin of the disc to preclude counter-clockwise rotation (as viewed in FIG. 1) of the injector after lugs 46, 48 have been passed through the disc and thereby eliminate the possibility that the injector might be twisted the wrong way. 
     Typically the fuel rail is fabricated from a suitable composite or relatively soft alloy material. The disc is typically fabricated from relatively harder spring sheet metal, and therefore the radially outermost edges will inherently tend to dig into the composite or relatively soft alloy material. The disc is assembled to the fuel rail by pressing it into the through-hole. The disc&#39;s teeth enable it to pass relatively easily into the through-hole but strongly resist removal or rotation once the disc has been pressed into place. 
     While a presently preferred embodiment of the invention has been illustrated and described, it should be appreciated that principles are applicable to other embodiments that fall within the scope of the following claims. While the illustrated fuel rail is intended to be mounted to an intake manifold of an engine, the fuel rail could be integrated into the manifold, and it is to be understood that use of the term &#34;fuel rail&#34; is intended to include both a separate as well as an integral fuel rail. In its more comprehensive aspects, the invention should be understood to encompass any of a number of various means of joining of the disc to the fuel rail other than those specifically illustrated; for example it is contemplated that with the use of suitable materials, the disc could be made of a composite that is joined to the composite of the fuel rail by conventional composite-joining procedures for the particular composite materials involved.