Rotation limiting connections between cross-over tubes and fuel rails for internal combustion engines

A mechanical rotation limiting connection, defined between the end of a rigid metal cross-over tube and the adjacent end of a fuel rail, is disclosed. The coupling comprises a fitting that is inserted into, and permanently joined to, an open end of the fuel rail. The fitting includes a body complementary in shape to the fuel rail, with an enlarged flange at its trailing end, a tapered leading section, and an axial bore of stepped configuration. The leading section of the cylindrical cross-over tube is deformed into a polygonal shape that fits into the bore of the fitting; a transition section and a round section extend inboard of the leading section, and an enlarged annular collar encircles the cross-over tube. The leading section of the cross-over tube is inserted into the fitting, and mechanical members on the fitting are deformed or crimped over the annular collar on the cross-over tube to lock the tube within the fitting, and prevent inadvertent disassembly. Clearance between the leading end of cross-over tube and the axial bore in the fitting permits limited rotational movement. The extent of the removement is limited by flats in the bore of the fitting, by the movement of an orientation bead within the cut-out segment of a trailing flange, or other mechanical constraints. An O-ring seated about the round section of the tube fits in the stepped bore of the fitting to prevent leakage.

FIELD OF THE INVENTION 
The instant invention relates broadly to connections between cross-over 
tubes and fuel rails that supply fuel to fuel injectors for an internal 
combustion engine. More particularly, the invention relates to diverse 
connections that are configured to allow limited rotation between the 
cross-over tubes and the fuel rails during assembly, and to the methods of 
forming and assembling such couplings. 
BACKGROUND OF THE INVENTION 
Fuel injected internal combustion engines have gained widespread acceptance 
as a fuel efficient alternative to conventional, carbureted engines. Fuel 
injected internal combustion engines are now electronically controlled by 
an on-board electronic control unit (ECU). 
Fuel is supplied to the injectors (one for each cylinder in the engine) by 
plastic, or metal, fuel tubes, of round, square, or rectangular shape, 
commonly known as fuel rails. The fuel rails are adapted to receive the 
injectors, at spaced internals, to align same with the inlet port for each 
cylinder. The individual injectors may be retained on the fuel rail by 
clips, or other mechanical members. The fuel rails, with the depending 
injectors, are mated with the engine block, during the assembly process. 
The mating of the fuel rail/injector subassembly, with the intake valves 
for the cylinders within the engine block, is relatively straightforward. 
However, when dealing with V-configured engines, such as V-6 or V-8 
cylinder banks, greater difficulty is encountered. Angular adjustments, or 
corrections, made during assembling the fuel rail/injector subassembly to 
the engine block, are reflected in angular mismatching between the fuel 
rails and the rigid cross-over tube(s) joining same together. The 
mismatching is complicated by the production requirements of the assembly 
line, and by the cramped space available to work within, or under, the 
hood of the automobile. 
The opposite ends of fuel rails are joined to rigid cross-over tubes 
associated with the supply, and return, sides, of the fuel system of the 
automotive vehicle. A representative fuel assembly (12) is shown in FIG. 1 
of U.S. Pat. No. 5,002,030, granted Mar. 26, 1991, to Randall M. Mahnke, 
and assigned to the assignee of the instant application. The assembly (12) 
includes fuel rails (14, 16), cross-over tubes (28, 36), and pressure 
regulator (38); the flow path of the fuel is indicated by directional 
arrows (42, 44). 
Quick, easily assembled, and reliable, connections must be established 
between the cross-over tubes and the fuel rails. Such connections must 
also be able to permit the cross-over tube to rotate relative to the 
longitudinal center-line of the fuel rail to compensate for any angular 
mismatch introduced during prior steps in the assembly process. 
A known coupling (46) that addresses these problems is shown in FIG. 4 of 
U.S. Pat. No. 5,002,030. Such coupling functions in concert with annular 
flange (52) that is spaced inwardly of the terminal end (28a) of the 
cross-over tube (28); the end of the cross-over tube is inserted into an 
axial recess (48) in the fitting (46) retained in the end of the fuel rail 
(16). An O-ring (58) situated between the fitting and the annular flange 
seals the connection. The coupling (46) comprises a retainer (54) with an 
arcuately shaped flange (56) that provides a saddle support for the 
cross-over tube, and a bolt (55) connects the retainer to the end of the 
fuel rail. The bolt prevents axial separation of the components, but the 
cross-over tube may rotate freely relative to the fuel rail. 
Another known coupling (46') is shown in FIG. 5 of U.S. Pat. No. 5,002,030. 
Such coupling includes a stepped fitting (60') that is inserted into the 
end of the fuel rail (16'); a stop (62') is formed at the inner end of the 
fitting, and a recessed surface (64') is formed near the entrance to the 
fitting. An annular flange (52') is formed on the cross-over tube. The 
terminal end (28a') of the cross-over tube (28') is inserted into the 
fitting, so that the inner end of the tube abuts the stop (62'). O-ring 
(65') fits into the recessed surface and cooperates with the annular 
flange to seal the coupling. A retaining flange (66'), at the entrance 
into the fitting, contacts the annular flange, and retains the components 
in cooperating relationship. Slight axial play is permitted between 
cross-over tube (28) and the fuel rail (16) is attainable, so that the 
O-ring seal (65') is not pinched. Consequently, the cross-over tube may be 
secured in the fitting, by crimping over flanges (67'); the cross-over 
tube may be rotated relative to the fuel rail, as noted in column 5, lines 
10-41. 
Whereas the couplings disclosed in U.S. Pat. No. 5,002,030, proved to be 
satisfactory in correcting for angular mismatches, such couplings require, 
and/or permit, a considerable degree of rotation between the cross-over 
tube and the fuel rail. The couplings utilize an annular flange on the 
cross-over tube to rotate upon an annular surface on the fitting inserted 
into the open end of the fuel rail. In some instances, wherein the engine 
compartment has reduced overhead, the degree of rotational movement of the 
cross-over tube must be reduced or curtailed, to suit the customer's 
demands, and existing couplings proved unable to meet the new operational 
criteria. 
The known couplings required the assembly of several components, and each 
operation adds to the time and cost considerations relevant to high speed 
production, and assembly of automotive components. Simpler couplings are 
constantly sought for original equipment manufacture, as well as for the 
repair and/or replacement after-market. 
Consequently, couplings with rotation limiting characteristics, which would 
permit rotational movement within prescribed limits, were sought. The 
limited extent of rotational movement would allow quick, accurate, and 
reliable couplings, even within sorely limited overhead space. 
SUMMARY OF THE INVENTION 
The instant invention contemplates a mechanical coupling, defined between 
the end of a rigid cross-over tube and a fitting inserted into a fuel 
rail, that is capable of limiting the rotational movement of the 
cross-over tube relative to the longitudinal center-line of the fuel rail. 
The rotational movement is sufficient to compensate for any mis-match 
between the fuel rail (and the fuel injectors operatively associated 
therewith) and the fuel injector cavities (usually located in the "head" 
of the engine). However, the extent of the rotation is limited to a 
specific angular range, so that the coupling can be installed, by a worker 
on an assembly line, in the relatively tight overhead space allotted by 
current automobile designs. 
The coupling may assume many forms, and shapes, but the common components 
for the four embodiments of mechanical coupling include (1) a rigid 
cross-over tube that has been (2) shaped or configured at its leading 
section to be inserted into a (3) fitting inserted into the open end of 
(4) an adjacent fuel rail. An annular collar (5) is defined on the 
cross-over tube, and (6) an O-ring fits over the cross-over tube and seats 
within the interior of the fitting to form a seal between the fitting and 
the cross-over tube. 
The fitting comprises a cylindrical body with a tapered leading edge and an 
enlarged flange that rests against the edge of the fuel rail and maintains 
the fitting in fixed axial position. The fitting is brazed into permanent 
engagement with the fuel rail. Ears or tabs at one end of the fitting may 
be crimped, or otherwise deformed, to lock the cross-over tube within the 
fitting. 
A bore extends axially throughout the body of the fitting. In contrast to 
the cylindrical bores in known couplings, the bore may assume different 
polygonal shapes. In one embodiment, for example, the bore is elliptical 
in shape, and receives a somewhat smaller, similarly shaped leading edge 
of the cross-over tube; one or more flats interrupt the elliptical shape 
of the bore. In another embodiment, the bore is defined, internally, by a 
series of alternating flat and arcuate sections that receive, and 
cooperate with, the leading end of the cross-over tube. The leading end of 
the cross-over tube has been formed into a polygonal shape, such as a 
rectangle, to be received within the bore of the fitting. The cross-over 
tube may also include an annular transition section inboard of the leading 
section, a round section located intermediate the transition section and 
an enlarged annular collar. The round section provides a concentric 
sealing surface for this O-ring. 
The instant invention further contemplates unique methods of forming, and 
assembling, the components for the coupling, including the step of forming 
at least one, and perhaps, as many as four, flattened sides on the leading 
end, edge or section, of the cross-over tube; and forming the axial, 
internal bore in the fitting, in a complementary manner. The cooperating 
surfaces on the cross-over tube and the interior of the bore of the 
fitting determine the extent of penetration of the cross-over tube into 
the fitting, while the clearance therebetween permits limited rotational 
movement. The deformed leading end of the cross-over tube represents the 
only area of contact between the cross-over tube and the fuel rail 
fitting, and thus the only relationship for limiting rotation. The limited 
rotational movement compensates for angular mismatch, within the reduced 
space above the engine block. 
In lieu of forming at least one flattened side at the leading end, or 
section, of the cross-over tube, all four sides may be flattened, or 
deformed, to define a rectangular section. A transition section is formed 
inboard of the leading section, and a rounded section, is located inboard 
of the transition section. The rounded section corresponds to the nominal 
dimension of the cross-over tube. An enlarged annular collar is formed 
inboard of the round section. Ears or tabs are formed at one end of the 
fitting. Consequently, after the leading edge of the cross-over tube is 
inserted into the fitting, to the desired depth or degree of penetration, 
the tabs on the fitting are crimped over the annular collar to secure the 
cross-over tube to the fitting and prevent removal therefrom. 
While the preferred embodiment of the instant coupling utilizes a 
cross-over tube with a leading end of rectangular cross-section to 
cooperate with a fitting with an axial bore of complementary shape, the 
leading end may have only one flattened surface, with the remainder of the 
cylindrical tube retaining its arcuate shape. Alternatively, the leading 
end of the cross-over tube may be elliptical in shape, for cooperation 
with a fitting having an axial bore of complementary shape, interrupted by 
one or more flats. Other geometrical shapes may also be suitable for the 
leading end of the cross-over tube, and the complementary shape of the 
axial bore in the cross-over fitting. 
In another novel method for forming, and assembling, the coupling, an 
orientation bead is formed, or brazed, onto the cross-over tube adjacent 
to the annular collar; the bead fits into a cut-out on the annular flange 
of the cross-over fitting. The extent of rotation of the coupling is 
thereby positively limited. 
The cross-over tube and the associated fitting are sturdy metal parts that 
contribute to an extended service life; the fitting is permanently joined 
to the tube rail, as by brazing. The cross-over tube is secured to the 
fitting by crimping ears at the upper end of the body of the fitting into 
locking engagement with the annular collar on the cross-over tube. An 
O-ring situated between the cross-over tube and the stepped inner bore of 
the fitting provides a leak-proof seal. 
Yet other operational advantages attributable to the four embodiments of 
the instant, rotation limiting coupling, will occur to the skilled 
artisan, when the accompanying drawings are construed in harmony with the 
appended specification. The several embodiments achieve the desired 
rotational limiting function, ease of manufacture, and facile assembly, 
without resorting to uniquely shaped clips, retainers, and the other 
specialty hardware components, that add cost and complexity to known 
couplings used in similar circumstances.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 depicts an exemplary internal combustion engine which employs a fuel 
rail assembly 12. Assembly 12 includes a pair of rigid, elongated tubular 
fuel rails 14, 16 disposed in substantially parallel orientation relative 
to one another. Fuel rail 14 supplies fuel to the inlet ends of a series 
of injectors 18 located in the inlet ports of one bank of combustion 
chambers of engine 10. Fuel rail 16 supplies fuel to the inlet ends of a 
series of injectors 20 located in the inlet ports of the other bank of 
combustion chambers of engine 10. 
A rigid, metal conduit, commonly known as a cross-over tube 22, joins fuel 
rails 14, 16 together. A second parallel cross-over tube 24, at the 
opposite face of the engine, joins that remote end of fuel rail 16 to fuel 
regulator 26, and thence to the to the return side of the fuel system for 
the vehicle (not shown). A more comprehensive discussion of fuel rail 
assembly 12, and the manner of operatively associating same with the inlet 
ports of the several combustion chambers of an internal combustion engine 
will be found in U.S. Pat. No. 5,002,030, granted to R. M. Mahnke. 
Connection 28 is employed to join one end of cross-over tube 22 to fuel 
rail 14, and a second, similar connection 30 is employed to join the 
opposite end of cross-over tube to fuel rail 16. Only connection 28 is 
illustrated, in detail, in FIGS. 2 and 3, but connector 30 is of similar 
configuration. 
End 30 of cross-over tube 22 is flattened, deformed, or otherwise shaped 
into a rectangular section 32. A transition section 34 is situated 
intermediate rectangular section 32 and round section 36. An annular 
collar 37 is located inboard, of section 36. Annular O-ring 38 fits over 
rectangular section 32, and collar 37 limits the movement of the O-ring 
along cross-over tube 22, as shown in FIG. 2. 
A cross-over fitting, indicated generally by reference numeral 42 fits into 
the open end of fuel rail 14 adjacent over tube 22, as shown in FIG. 3. 
Fitting 42 comprises a cylindrical body 44 with a tapered leading end 46, 
also called a chamfer, and an enlarged annular flange 48 at its trailing 
end. Bore 50 extends axially through cross-over fitting 42. 
Bore 50 is divided along its axial length into steps of different widths. 
The bore is narrowest at bottom step 52, widens slightly at intermediate 
step 54, gradually widens through tapered step 56, and reaches its maximum 
width at step 58. Alternating flats 60 and arcuate segments 62 extend 
around bottom step 52 in bore 50, as shown in FIG. 3. The size of 
rectangular end 32 of cross-over tube 22, relative to step 52 of bore 50 
of fitting 42, is indicated by the dotted outline in FIG. 3. 
Fitting 42 is inserted into the open end of fuel rail 14, so that flange 48 
abuts the fuel rail and body 46 extends into the fuel rail. O-ring 38 is 
seated about transition section 34 of end 30 of cross-over tube 22, and is 
located within step 58 of bore 50, as shown in FIG. 4, to prevent leakage 
between fuel rail 14 and cross-over tube 22. Rectangular section 32 of 
cross-over tube 22 fits clearly within step 52 of bore 50, and adequate 
clearance is maintained on all sides. After cross-over tube 22 is properly 
seated in fitting 42, tabs 64, situated at the upper end of fitting 42, 
are deformed, crimped, or otherwise folded over annular collar 37 on 
cross-over tube 22 to lock the cross-over tube in fixed axial position. 
DESCRIPTION OF ALTERNATIVE EMBODIMENTS 
A first alternative embodiment of the unique coupling for securing one end 
of a cross-over tube to one end of a fuel rail, while limiting relative 
rotation therebetween, is shown in FIGS. 5 and 6. Whereas the preferred 
embodiment of the coupling, shown in FIGS. 1-4, is identified generally by 
reference numeral 28, the first alternative embodiment, shown in FIGS. 
5-6, is identified generally by reference numeral 128. 
The leading section 130 of cross-over tube 122 is D-shaped, with a hollow 
bore 131 and a flattened surface 132. A transition section 134 is formed 
inboard of surface 132, and a rounded section 136 extends inwardly from 
transition section 134. An enlarged annular collar 137 is situated inboard 
of rounded section 136. The diameter of rounded section 136 is equal to 
the diameter of cross-over tube 122. An O-ring 138 is slipped over the 
leading section 130 of cross-over tube 122; the axial movement of O-ring 
138 is limited by annular collar 137. 
Cross-over fitting 142 comprises an integral body composed of several 
sections including a cylindrical body 144 with a tapered leading edge 146, 
an enlarged flange 148, and a D-shaped section 149. A bore 150, of stepped 
configuration, extends axially through fitting 142, and a stop 151 is 
situated between leading edge 146 and D-shaped section 149, as shown in 
FIG. 5. The step within bore 150 cooperates with complementary surfaces on 
cross-over tube 122 to limit the penetration of the tube, into the 
fitting, during assembly. 
FIG. 6 shows the leading section of cross-over tube inserted axially into 
cross-over fitting 142 so that transition section 134 abuts against stop 
151. O-ring 138 is retained in sealing position by collar 137, and the 
O-ring fits within the largest step in bore 150 of fitting 142. Tabs 164 
at the upper end of fitting 142 are crimped over to retain collar 137 on 
cross-over tube 122 and prevent accidental disassembly. Flange 148 seats 
cross-over fitting 142 within the fitting in the open end of fuel rail 14 
(not shown in FIG. 6). 
A second alternative embodiment of the unique coupling for securing one end 
of a cross-over tube to a fuel rail, while limiting relative rotation 
therebetween, is shown in FIGS. 7 and 8. Whereas the preferred embodiment 
of the coupling is identified generally by reference numeral 28, and the 
first alternative embodiment is identified by reference numeral 128, the 
second alternative embodiment is identified by reference numeral 228. 
The leading section 230 of cross-over tube 222 is elliptically shaped, and 
shown in FIG. 7, and a transition section 232 is formed inboard of leading 
section 230, and round section 234 is inboard of transition section 232. 
An enlarged annular collar 236 is formed adjacent round section 234. 
O-ring 238 is slipped over the leading section 230 of cross-over tube 222. 
Cross-over fitting 240 comprises an integral body composed of several 
sections, including a cylindrical body 242 with a tapered leading edge 
244, an enlarged flange 246, and an axial bore 248, and interrupts the 
otherwise elliptical bore. The bore extends axially through the fitting, 
and one or more flat sections 252 extend at least partway through bore 
250. The bore is complementary in shape, and slightly larger than, the 
elliptical shape of leading section 230 by cross-over tube 222. 
FIG. 8 shows the leading section 230 of cross-over tube 222 inserted 
axially into the bore 248 of cross-over fitting 240 so that collar 236 
presses against O-ring 238, which is seated in an enlarged step 252 in 
bore 248. Ears 254, at the upper end of fitting 240, are crimped over 
collar 236, to prevent cross-over tube 222 from being withdrawn from 
fitting 240, and disassembling coupling 228. The clearance between leading 
section 230 on cross-over tube 222 and bore 248 of fitting 240 allows 
relative motion therebetween; the extent of movement is limited by the 
rounded surfaces of leading section 230 contacting flat section 250 within 
bore 248. 
A third alternative embodiment of the unique coupling is shown in FIGS. 9 
and 10. Whereas the preferred embodiment of the coupling is identified 
generally by reference numeral 28, the first alternative embodiment is 
identified generally by reference numeral 128, and the second alternative 
is identified generally by reference numeral 228. The third alternative 
embodiment is identified generally by reference numeral 328. 
The leading section 330 of cross-over tube 322 is cylindrical in shape; and 
an enlarged annular collar 324 is situated inboard of the leading section. 
An orientation bead 326 is welded or otherwise joined to collar 324, and 
extends axially inward from collar 324. And an O-ring 332 slips over 
leading section 330 of cross-over tube 322, but collar 324 limits its 
axial movement. 
Cross-over fitting 334 comprises a cylindrical body 336 with a tapered 
leading edge 338, and an axially projecting nose 340, and an enlarged 
annular flange 342. A trailing ring 344 is located at the upper end of the 
fitting, and an arcuate segment 346 is removed from ring 344. As shown in 
FIG. 10, the extent of relative rotation between cross-over tube 322 and 
fitting 334 is defined by the movement of orientation bead 326 within the 
arcuate segment 346 of ring 344. Ring 344, as shown in FIG. 10, is crimped 
over collar 324, to complete the coupling 338, and to prevent cross-over 
tube 322 from inadvertently being removed from fitting 334. 
Other refinements, modifications, and alterations, will occur to the 
skilled artisan from a consideration of the four embodiments discussed 
above. While the connections have been described with respect to 
cross-over tubes joined to fuel rails, the connections have other 
applications; for example, the connections may be used for in-line, single 
tube applications, or could be used to prevent inlet or outlet (supply or 
return) tubes, for a fuel distribution system, from rotating prior to 
assembly, thereby preventing problems after assembly. Consequently, the 
appended claims should be broadly construed in a manner consistent with 
the significant advances in the useful arts and sciences, and should not 
be limited to their literal terminology.