Manifold for a system for supplying fuel to an internal-combustion engine

Abstract: The manifold (1) supplies fuel under pressure to a series of fuel metering and atomising valves, and comprises a first tubular body (2) provided with a series of connections (3) for the valves; a second tubular body (4) arranged approximately coaxially inside the first tubular body (2) to define between these bodies a channel (5) for supplying the fuel to the connections (3); a first member (8) arranged so as to close off a first axial end of the first tubular body (2); and a second member (10) arranged so as to close off a second axial end of the first tubular body (2). The chief characteristic of the manifold (1) lies in the fact that the second member (10) comprises a wall (11) which closes off said first tubular body (2) and that this wall (11) is made in one piece with the first tubular body (2).

Description: The present invention relates to a manifold for a system for supplying fuel to an internal-combustion engine. In particular, the manifold supplies fuel under pressure to a series of fuel metering and atomising valves. Manifolds of this type normally comprise a first tubular body provided with a series of connections for the aforesaid valves, and a second tubular body arranged coaxially inside the first to define between the first and second tubular bodies a fuel supply channel to said connections. The first and second tubular bodies are closed at a first end by a pressure regulator which maintains the pressure of the fuel inside the supply channel below a preset value, and at a second end by an obturator. The obturator comprises a first cylindrical portion whose diameter is equal to the internal diameter of the first tubular body to enable it to engage in said second end of the first tubular body. The obturator also comprises a second cylindrical portion which extends coaxially from the first portion, its diameter being equal to the internal diameter of the second tubular body so as to engage the second end of the second tubular body when the first portion closes the first tubular body. Lastly, the obturator comprises a seal around said first portion to prevent fuel leaking from the manifold. Manifolds of the type described above have many drawbacks, the chief of which is that with time said obturator can loose its leaktightness and consequently permit fuel to escape. The object of the present invention is to provide a manifold for a system for supplying fuel to an internal-combustion engine, without the drawback described above. In EP-A-403871, which represents the closest state of the art is described a manifold in which the first tubular body defines a wall made in one piece with said first tubular body and closes off the tubular body itself; the first tubular body comprises a fuel inlet connector and a fuel outlet connector projecting laterally from the end of the body. In a manifold of this type the above mentioned obturator is missing, but the structure and the shape of the first tubular body are complicated and therefore in order to produce the body complex moulds are required. According to the present invention a manifold is made for a supply system for an internal-combustion engine as defined By claim 1. The invention will now be described with reference to the appended drawings, which illustrate a non-restricting embodiment thereof. In the drawings: Figure 1 shows a longitudinal section of a fuel supply manifold made according to the specifications of the present invention; and Figure 2 is a side elevation of the manifold shown in Figure 1. With reference to Figure 1, 1 indicates a manifold for a system for supplying fuel to an internal-combustion engine. The manifold 1 comprises a tubular body 2 provided with a series of connections 3 for fuel metering and atomising valves, of known type, one being illustrated partially in Figure 2. The manifold 1 also comprises a second tubular body 4 which is arranged in an approximately coaxial position inside the first body 2 to define with said first body 2 a channel 5. The channel 5 is defined by the internal surface 6 and external surface 7 of the tubular bodies 2 and 4 respectively and communicates with the connections 3 so as to supply fuel to said valves. The manifold 1 also comprises a first member 8 which closes off the tubular body 2. The member 8 is formed by a known type of pressure regulator mounted so as to close off a first axial end of the tubular body 2 and a first end of the tubular body 4, and maintains the pressure of the fuel inside the channel 5 within a preset range of values. As is known, the pressure regulator has a spring (not shown) as a means of clamping to the manifold 1. Lastly, the manifold 1 comprises a second member 10 for closing off a second axial end of the tubular body 2. The member 10 comprises a wall 11 made in one piece with the tubular body 2. The wall 11 contains a first duct 12 which starts in a tubular extension 13 and leads into the channel 5. The extension 13 is made in one piece with the wall 11 from whose outer face it projects coaxially with the body 2. The extension 13 is externally threaded to permit a hydraulic coupling with a pipe (not shown) supplying fuel from a tank (not shown). The duct 12, from the inside to the outside of the body 2, is defined by a first section whose axis is parallel to the longitudinal axis of the body 2, by a second section whose axis is at an angle to the axis of the first section, and by a third section whose axis is approximately coaxial with the longitudinal axis of the body 2. The wall 11 contains a second duct 14 leading in an "L"-shaped path between an inner face of the wall 11 and the lateral surface of this same wall 11. At the inner face of the wall 11, the duct 14 widens out to form a coupling seat 15, sealed off from the channel 5, for an axial end portion of said tubular body 4. In particular, an annular flange 20 is formed at said end portion of the body 4 to abut against the free rim of the seat 15. Furthermore, between the seat 15 and the end portion of the body 4, an annular seal 21 is installed. Formed in one piece with the wall 11 is a tubular extension 16 which extends radially away from said lateral surface of said wall 11. There passes axially through the extension 16 a terminal section of the duct 14, and at the free end of this extension 16 is a seat 17 providing leaktight accommodation for a first end portion of a body 18, of which a second end portion is provided for attachment to a tube (not shown) for sending fuel to said tank (not shown). The body 18 is "L"-shaped so that the axis of its second end portion is parallel to the longitudinal axis of the body 2. In the manifold 1, the tubular body 4 also has fins 19 along the channel 5 to centre said body 4 in a preset position with respect to the body 2. The body 2 is made in one piece with the wall 11 by the stamping method in such a way as to define a single aperture produced by the stamp punch; this aperture will later be sealed shut by the pressure regulator. The body 2 may be made in a metal material, preferably rheocast aluminium, or in a plastics material. With the stamping method used for the construction of the body 2, this body is given an internal taper with a small deforming angle. The body 4 may likewise be made of a metal or plastics material. In use, after manufacture of the body 2 and the wall 11 in one piece with the body 2, the body 4 is inserted into the body 2, the seal 21 having been already fitted onto its first end. The body 4 is inserted until the flange 20 stops against the free rim of the seat 15. After this, the pressure regulator is installed so as to seal off the body 2. The pressure regulator includes a portion which connects with a second axial end of the body 4. As already stated, the pressure regulator has a spring to clamp it against the manifold 1. This spring additionally has the function of pressing the body 4 in the direction of the seat 15 so that the position of the body 4 and the seal between the end portion of the body 4 and the seat 15 are held constant. The fuel passes along the duct 12 from the tank into the channel 5 and from here is distributed to the metering valves. Should the pressure in the channel 5 rise above a preset value to which the regulator has been calibrated, the regulator compensates for this by recycling the fuel to the tank via the body 4. It is clear from the aforegoing description what advantages result from the use of the present innovation. In particular, it provides a manifold whose fuel feeder body has only one obturator (the pressure regulator) since at the further end from this obturator there is a closure wall made in one piece with the feeder body. It is clear that in such a manifold the seal will be more reliable and that as a consequence there will be a marked decrease in the risk of fuel leakage. What is more, the manifold has fewer components than current manifolds owing to the elimination of one member (the obturator at the far end from the pressure regulator), in itself a critical member; whence reduced costs not only of assembly but also of testing. The particular shaping of the closure wall 11 and the presence of the fins 19 enables accurate, fast and efficient assembly of the recyling body 4 along the body 2, and of the pressure regulator at the ends of these bodies 2 and 4. It should be noted, too, that the stamping method enables the body 2 to be manufactured on an industrial scale and at a low cost.

Claims: Manifold for a supply system for an internal-combustion engine, which manifold supplies fuel under pressure to a series of fuel metering and atomising valves, and comprises a first tubular body (2) provided with a series of connections (3) for said valves; a second tubular body (4) arranged approximately coaxially inside said first tubular body (2) to define between said first (2) and said second (4) tubular bodies a channel (5) for supplying the fuel to said connections (3); a first member (8) arranged so as to close off a first axial end of said first tubular body (2) and preferably defined by a pressure regulator; and a second member (10) arranged so as to close off a second axial end of said first tubular body (2); said second member (10) comprises a wall (11) which closes off said first tubular body (2), said wall (11) being made in one piece ,with said first tubular body (2) characterised in that said wall (11) contains a first duct (12) which starts in a first tubular extension (13) and leads into said channel (5); said first extension (13) being made in one piece with said wall (11) from whose outer face it projects coaxially with said first body (2), and being able to be hydraulically coupled to a tube supplying fuel from a tank. Manifold according to Claim 1, characterised in that said duct (12), from the inside to the outside of said first body (2), is defined by a first section whose axis is parallel to the longitudinal axis of said first body (2), by a second section whose axis is at an angle to the axis of said first section, and by a third section whose axis is approximately coaxial with the longitudinal axis of said first body (2). Manifold according to at least one of the preceding claims, characterised in that said wall (11) contains a second duct (14) providing hydraulic connection between said second body (4) and said tank. Manifold according to Claim 3, characterised in that said second duct (14) leads in an "L"-shaped path between an inner face of said wall (11) and the latter's lateral surface; at the inner face of said wall (11) said second duct (14) presenting a first coupling seat (15) sealed off from said channel (5), for an axial end portion of said second body (4). Manifold according to Claim 4, characterised in that formed in one piece with said wall (11) is a second tubular extension (16) which extends radially away from said lateral surface of said wall (11); there passing axially through said second extension (16) a terminal section of said second duct (14), and there being at the free end of this extension (16) a second seat (17) providing leaktight accommodation for a first end portion of a third body (18), of which a second end portion is provided for hydraulic attachment to a tube for sending fuel to said tank. Manifold according to Claim 4 and/or Claim 5, characterised in that an annular flange (20) is formed at said end portion of said second body (4) to abut against the free rim of said first seat (15); there being installed between said first seat (15) and said end portion of said second body (4) an annular seal (21). Manifold according to any one of the preceding claims, characterised in that it has fins (19) along said channel (5) to centre said second body (4) in a preset position with respect to said first body (2). Manifold according to any one of the preceding claims, characterised in that said first body (2) is made in one piece with said wall (11) by the stamping method in such a way as to define a single aperture produced by the stamp punch; said aperture being sealed shut by said first member (8). Manifold according to Claim 8, characterised in that said first body (2) is made of a metal material, preferably rheocast aluminium. Manifold according to Claim 8, characterised in that said first body (2) is made of a plastics material. Manifold according to any one of the preceding claims, characterised in that said second body (4) is made as desired of a metal or plastics material.

Inventors: DI SILVESTRO MAURIZIO, GIOVANNINI FLAVIO, DI SILVESTRO, MAURIZIO, GIOVANNINI, FLAVIO
Applicants: MAGNETI MARELLI SPA, MAGNETI MARELLI S.p.A.
Application year: 1993
Main classification: F02M55
IPC codes: F02M69