Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-01-18
2001-03-06
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S468000
Reexamination Certificate
active
06196192
ABSTRACT:
This application is the national phase of international application PCT/FR99/01180 filed May 18, 1999 which designated the U.S.
The invention concerns a fuel distribution system for feeding the cylinders of an internal-combustion engine, in particular a fuel-injected engine and more particularly still an engine fed at a relatively high pressure.
The invention relates more particularly to a new method of making a system of the above kind, which is easy to fabricate, easy to install and low in cost.
In a fuel-injected internal-combustion engine, the fuel distributor conventionally includes an elongate, generally tubular body connected by one axial end to the outlet of a fuel pump and having a plurality of outlets in the form of projecting bosses along its length. The outlets are connected to the various injectors. Other connections may be provided for connection to pressure and/or temperature sensors, a damper or a regulator. The elongate tubular body is difficult to make. It requires a heavy one-piece component that requires finish-machining.
An elongate tubular body of the above kind also incorporates a plurality of supports or attachment lugs for fixing it to the engine block. In practice the very shape of a distributor of the above kind and the need to fix it at a number of points necessitate a specific design for each type of engine.
European patent application No 0 427 977 describes a distributor including a short elongate cavity mounted on a base incorporating a pressure and/or temperature sensor. The ports of the cavity including an inlet connected to the pump and outlets connected to the injectors are grouped together at one end of the body. These ports communicate with the cavity via bores. Most of the bores are at a slant and open into the upper part of the cavity. A distributor of the above kind is difficult and costly to make. The walls of the body are relatively thick and the component is heavy.
The invention proposes a new type of fuel distribution system which is easy to mass produce at relatively low unit cost.
One object of the invention is to propose a small and light distributor which is particularly highly resistant to high pressures.
Another object of the invention is to propose a distributor of the above kind which can have a large number of ports for connection to the various cylinders and sensors of the engine and which can be disposed at numerous locations on said body.
Another object of the invention is to propose a distributor in which the cavity is of particularly small volume but nevertheless capable of feeding at a high pressure a relatively large capacity engine, all other things being equal.
The invention relates more particularly to a distribution system for feeding the cylinders of an internal-combustion engine, of the type including a hollow body in the wall of which are formed ports adapted to be connected, in particular, to a supply of fuel under pressure and to a plurality of injectors for feeding said cylinders, characterized in that said hollow body includes a part of a cavity which is at least approximately spherical or has an oblong profile and a shouldered bore extending substantially radially between said cavity part and an orifice of said body, said bore including, separated by a shoulder, an interior first section communicating with said cavity part and a threaded exterior second section, and in that an arrangement for plugging said bore has an inside part engaged in said first section, constituting a part of the inside face of said cavity, and a threaded part screwed into said second section.
The cavity can be spherical, substantially spherical or have a slightly oblong profile.
The inside part of the plugging arrangement can include a recess completing said cavity. A seal can be disposed between the plugging arrangement and said bore.
The spherical or practically spherical shape of the cavity is advantageous because all the ports can communicate with the cavity via bores whose inside end parts, at least, are substantially radial. This means that the ports can be anywhere on the body all around the spherical or practically spherical cavity.
Most importantly, the screwed assembly of the hollow body and the plugging arrangement reduces very substantially the manufacturing costs for an astonishingly high resistance to pressure.
In various embodiments of the invention the inside part of the plugging arrangement is separate from the threaded part. The inside part can include a first shoulder cooperating with that of the bore, in which case the seal between said body and said inside part cannot be damaged when said threaded part is screwed on. This shoulder is referred to hereinafter as the “first shoulder”.
The seal can be accommodated in an annular groove formed in a cylindrical portion of said inside part. This seal can also be compressed between two shoulders, one of which is that of said bore. The shoulder of the bore can be beveled to create an annular space adapted to house a seal of appropriate shape.
There can also be an at least relatively flat seal disposed between the shoulder of the bore and said first shoulder of said inside part. As before, the shoulder of said shouldered bore can be beveled to define an enlarged annular space with said first shoulder of said inside part.
In this case, said relatively flat seal includes an annular increased thickness in the vicinity of its inside edge adapted to occupy the enlarged annular space.
In some cases the inside part of the plugging arrangement and the threaded part can be in one piece.
Finally, in accordance with another advantageous feature of the invention, the volume of the cavity can be relatively small compared to the cylinder capacity of the engine to be fed. For example, for a 6-cylinder 2.5 liter engine with direct injection at a pressure in the order of 1500 bars, the volume of the cavity can be 30 cm
3
.
REFERENCES:
patent: 5471959 (1995-12-01), Sturman
patent: 6096119 (2000-08-01), Maier et al.
patent: 196 47 049 (1998-06-01), None
patent: 427 977 (1991-05-01), None
Browdy and Neimark
C I D E B
Moulis Thomas N.
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