HIGH PRESSURE HOSE FOR MODULAR FUEL DELIVERY SYSTEM

Abstract: A high-pressure fuel hose (64) for disposition between a tubular stem (30) on a fluid connector (28) on a canister (12) in a fuel tank and a tubular stem (60) on a fluid connector (52) on a cover (36) for the fuel tank spaced from the canister (12). Each of the tubular stems (30,60) has a fir-tree barb (32A,32B,62A,62B) thereon and the high-pressure hose (64) includes a convoluted flexible body (74) and a pair of relatively stiff cylindrical ends (78A,78B), each of which has a pair of annular inside beads (86A,86B) and three annular outside beads (88A,88B,88C) between the convoluted body (74) and the inside beads (86A,86B). When the cylindrical ends (78A,78B) are press-fitted over the fir-tree barbs (32A,32B,62A,62B) with force applied at the outside beads (88A,88B,88C), the inside beads (86A,86B) seat behind annular shoulders (84A,84B) on the barbs (32A,32B,62A,62B) for enhanced retention.

Description: This invention relates to high-pressure hoses in modular fuel delivery systems on automobile fuel tanks as specified in Claim 1. An example of a hose is disclosed in US-A-3,794,080. Manufacturing economies are achieved by grouping several functionally-related components into a module which is handled and installed as a unit. In automotive fuel systems, for example, modular fuel delivery systems have been proposed for direct installation on a fuel tank. Such systems are typically inserted through a hole in the top of the fuel tank and usually include a reservoir canister, a pump in the canister, a cover for the hole in the tank, elements for attaching the canister to the cover, and a flexible high-pressure hose for conducting high-pressure fuel from the pump to a fluid connector on the cover. The high-pressure hose may be of rubber or of flexible plastics material and is usually provided with a loop section to accommodate thermal and pressure-induced expansion and shrinkage of the gap between the canister and the cover. The ends of the high-pressure hose are typically pushed over tubular stems of fluid connectors and retained either by the natural resilience of the hose gripping annular "fir-tree" or similar barbs on the stems or by hose clamps around the outside of the hose. A high pressure blow-moulded elastomeric hose according to this invention as specified in claim 1 includes structural features at its ends which minimize the difficulty of pushing the ends over the tubular stems and which maximize resistance to dislodgment of the ends from the stems. This invention is a new and improved high-pressure hose between a pump in a canister of a modular fuel delivery system on an automobile fuel tank and a cover closing an access hole in the tank. The high-pressure hose according to this invention is made of fuel-resistant, blow-mouldable elastomer, preferably a commonly-available material such as NYLON 11, and includes a flexible body having a plurality of annular sinusoidal convolutions, a pair of relatively stiff non-convoluted cylindrical ends, a pair of inside annular beads on each cylindrical end, and a plurality of outside annular beads on each cylindrical end. The inside beads on each cylindrical end are pushed over and co-operate with annular "fir-tree" barbs on tubular stems of fluid connectors to maximize resistance to dislodgment of the cylindrical ends from the stems. The outside beads on the cylindrical ends define convenient abutments whereby the cylindrical ends can be engaged without radial distortion by pushing implements required to push the relatively stiff cylindrical ends and inside beads over the "fir-tree" barbs. In a preferred embodiment of the high-pressure hose according to this invention, the inside beads have radial heights not exceeding about 4.5% of the inside diameter of the cylindrical ends of the hose and the outside beads have similar radial heights of not less than about 4.5% of the inside diameter of the cylindrical ends of the hose. The invention and how it may be performed are hereinafter particularly described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a modular fuel delivery system having a high-pressure hose according to this invention; Figure 2 is a perspective view of a high-pressure hose according to this invention; Figure 3 is an exploded perspective view of a connection between a high-pressure hose according to this invention and a tubular stem of a fluid connector; and Figure 4 is a sectional view taken generally along the plane indicated by lines 4-4 in Figure 3 and showing the tubular stem in place relative to the high-pressure hose according to this invention. As seen best in Figure 1, a modular fuel delivery system 10 includes a reservoir canister 12 having a top 14 and a cylindrical wall 16 with a flat side 18. A metal bracket 20 is rigidly attached to the reservoir 12 parallel to the flat side 18. A fuel level transducer 22 is rigidly attached to the bracket 20 between the latter and the flat side 18 and includes a float 24 on an arm 26 which pivots with changes in the surface level of the fuel in a tank, not shown, on which the fuel delivery system 10 is installed. A fluid connector 28 having a tubular stem 30 is attached to the top 14 of the canister 12. The tubular stem 30 has a pair of fir-tree barbs 32A-32B thereon, as shown in Figures 1, 3 and 4. The discharge port of a conventional electric fuel pump, not shown, in the canister 12 communicates with the stem 30 below the top 14. The electric pump is connected to the electrical system of an automobile on which the fuel delivery system is mounted through an in-tank portion 34 of the wiring harness of the vehicle. When the ignition of the vehicle is switched on, the pump delivers high-pressure fuel to the stem. The fuel delivery system 10 further includes a cover 36 for closing a hole in a top wall, not shown, of the fuel tank. The cover 36 is a flat plastics disc having a upper, exposed surface 38, a lower, inside surface, not shown, facing the canister 12, and an integral depending flange 40. The disc has an annular shoulder 42 radially outboard of the depending flange 40 which seats against a seal, not shown, on the top wall of the tank around the access hole. Conventional means, not shown, clamp the cover 36 to the top wall of the tank. The cover has a moulded-in or otherwise sealingly-attached electrical connector 44 which defines a junction between the in-tank portion 34 of the wiring harness and an outside portion 46 of the wiring harness. The cover 36 is connected to the canister 12 by a plurality of identical hollow struts 48. Each strut has an upper end press-fitted into a socket, not shown, in the cover 36 and a lower end telescopically-received in a cylindrical bore in the top 14 of the canister. Coil springs 50 are each disposed around respective ones of the struts and urge relative separation between the cover 36 and the canister 12. Stops, not shown, at the lower ends of the struts 48 limit the relative separation between the canister and the cover. The springs maintain the canister 12 in contact with the bottom of the fuel tank so that the fuel level signal from the transducer 22 is bottom-referenced. The cover 36 has a plurality of moulded-in fluid connectors including a high-pressure connector 52, a vapor connector 54, and a low-pressure, return fuel connector 56. On the exposed surface 38 of the cover, the high-pressure connector includes an outside tubular stem 58 on which are formed a plurality of annular "fir-tree" barbs. The outside stem 58 receives the end of a fuel hose, not shown, through which high-pressure fuel is directed to the engine of the vehicle. Below the inside surface of the cover 36, the high-pressure connector 52 includes an inside tubular stem 60 on which are formed a pair of annular "fir-tree" barbs 62A, 62B. A high-pressure hose 64 according to this invention is disposed between the stem 30 of the connector 28 on the canister top 14 and the inside tubular stem 60 of the high-pressure connector 52 on the cover 36. The high-pressure hose 64 according to this invention includes a tubular body 74 having a plurality of annular sinusoidal convolutions 76 and a pair of integral, relatively inflexible cylindrical ends 78A, 78B. The high-pressure hose 64 is blow-moulded from fuel-resistant plastics material, preferably a commonly-available material such as NYLON 11. NYLON 11 is commercially available from ATOCHEM, Inc., Glen Rock, New Jersey, U.S.A. Non-convoluted hoses made of NYLON 11 have been used in the past as high-pressure hoses in automotive fuel systems. In addition, both longitudinally-split and unsplit convoluted hoses made of NYLON have been used by Packard Electric Division, General Motors Corporation, in automobile wiring harnesses to protect bundles of wires inside the hoses. The cylindrical end 78A and its connection to the tubular stem 30 of the connector 28 is representative of both cylindrical ends of the high-pressure hose and has a circular end 80 having an inside diameter D1, see Figure 3. Each of the "fir-tree" barbs 32A, 32B on the tubular stem 30 of the connector 28 has a tapered, frustoconical wall 82A, 82B leading to an annular shoulder 84A, 84B around the stem having an outside diameter D2, see Figure 3, exceeding inside diameter D1. As seen best in Figures 2-4, the cylindrical end 78A is inwardly indented to define a pair of annular inside beads 86A,86B near the circular end 80 thereof. The beads 86A, 86B are axially spaced a distance corresponding to the spacing between the annular shoulders 84A, 84B on the tubular stem 30. Each bead 86A, 86B has a radial height H1, see Figure 3, not exceeding about 4.5% of the diameter D1 of the circular end 80. Inside beads of this general dimension have been found to afford acceptable retention on a NYLON 11 high-pressure hose having a cylindrical end with D1 equal to about 8.05mm. The cylindrical end 78A is outwardly indented to define three annular outside beads 88A, 88B, 88C between the body 74 of the high pressure hose and the inside beads 86A, 86B. Each outside bead 88A, 88B, 88C has a radial height H2, see Figure 4, not less than about 4.5% of the inside diameter D1 of the cylindrical end 78A. Outside beads of this general dimension have been found to provide acceptable abutments for press-fitting cylindrical ends with D1 equal to about 8.05mm on "fir-tree" barbs with D2 equal to about 10.96mm. The high-pressure hose 64 is looped between the tubular stems 30 and 60 to accommodate thermal or pressure-induced expansion and shrinkage of the gap between the canister 12 and the cover 36. The radial height H1 of the inside beads 86A, 86B is an important feature of this invention because it increases the retention of the cylindrical end 78A of the high-pressure hose 64 on the tubular stem 30. In a preferred embodiment of the high-pressure hose 64, the inside diameter D1 of the hose is about 2.91mm smaller than the outside diameter D2 of the annular shoulders 84A, 84B. This amount of interference between the hose and the stem permits the relatively stiff cylindrical end to be pushed over the fir-tree barbs without collapsing the cylindrical end. The retention afforded by the interference alone, however, is not sufficient for high-pressure applications where fuel pressure is of the order of 1103.16 kPa (160 psi). Under that condition, the inside beads 86A, 86B afford additional retention sufficient for the higher pressures. The inside beads 86A, 86B incrementally increase the force required to push the cylindrical end 76A over the "fir-tree" barbs 32A, 32B on the tubular stem 30 to levels beyond manual capability. The annular outside beads 88A, 88B, 88C define abutments on the cylindrical end suitable for engagement by any convenient vice-like fixture, not shown, whereby axial force is applied to the cylindrical end 78A between the convoluted body 74 and the inside beads 86A, 86B. Because the outside beads stand above the outside surface of the cylindrical end 78A, indenting or gouging or otherwise radially deforming the cylindrical end is not required for press-fitting the cylindrical end on the tubular stem 30.

Claims: A high-pressure blow-moulded elastomeric hose (64) in a modular fuel delivery system (10) including a canister (12) with a fluid connector (28) thereon having a first tubular stem (30) including a fir-tree barb (32A,32B) formed thereon which has an annular shoulder (84A,84B) with a first outside diameter (D2), and a cover (36) connected to said canister (12) and spaced therefrom by a variable gap and having a high-pressure fluid connector (52) thereon including a second tubular stem (60) having a fir-tree barb (62A,62B) formed thereon which has an annular shoulder with said first outside diameter (D2), said high-pressure blow-moulded elastomeric hose (64) comprising: a flexible body (74) having a plurality of annular sinusoidal convolutions (76); and a pair of integral cylindrical ends (78A,78B) at opposite ends of said body (74), each having an inside diameter (D1) less than said first outside diameter (D2) and each being adapted for press-fit engagement on said fir-tree barb (32A,32B;62A,62B) on a respective one of said first and said second tubular stems (30,60); there being at least one annular inside bead (86A,86B) defined on each of said cylindrical ends (78A,78B) engaged behind a respective annular shoulder (84A,84B) on said respective one of said fir-tree barbs (32A,32B,62A,62B) for increased retention of said cylindrical ends (78A,78B) on said first and said second tubular stems (30,60); and there being at least one annular outside bead (88A,88B,88C) integrally formed on each of said cylindrical ends (78A,78B) between said convoluted body (74) and all of said annular inside beads (86A,86B), at which force can be applied to press-fit each of said cylindrical ends (78A,78B) on respective ones of said first and said second tubular stems (30,60). A high-pressure hose according to claim 1, characterised in that each inside annular bead (86A,86B) has a radial height not exceeding about 4.5% of said inside diameter (D1), and each outside annular bead (88A,88B,88C) has a radial height not less than about 4.5% of said inside diameter (D1).

Inventors: BEER, ROBERT CLAIR, COHA, TIMOTHY FRANCIS, GRIFFITH, SAMUEL G.
Applicants: GENERAL MOTORS CORPORATION
Application year: 1990
Main classification: F16L33
IPC codes: F16L11, F16L33, F02M37