"Improved injector for gas systems" Technical Field

This invention relates to an improved injector for gas systems. More in particular, this invention relates to an improved injector that carries out the dosing and distribution of fuel in alternative endothermic engines totally or partly fed by methane gas or LPG (Liquid Petroleum Gas); injectors of this type are preferably mounted on ramps and a solution is widespread wherein the methane gas or LPG enters a storage volume, common to the various engine cylinders, where it is dosed and delivered to the cylinders themselves through the controlled opening of the various injectors. Background Art In most injectors for gas systems at issue, the passage of the fuel flow to the engine takes place by means of the opening of a hole of the injectors themselves; such opening is obtained by the movement of the mobile core or part of an electromagnet. The mobile metal core of the electromagnet, also called mobile anchor or piston, is made to move from the position wherein it closes the hole to that wherein it opens it and, in this last condition, it contacts the fixed part of the electromagnet, also made of metal. Each time the aforementioned hole is opened, which takes place many times a second, the

percussion between the two metal components takes place, which causes noise.

An O-ring is traditionally used in order to obviate such drawback, generally arranged in the mobile anchor or part of the electromagnet, with an anti-noise function; such ring, in fact, is arranged between the metal surfaces of the two components that would contact each other whenever the injector is opened. It has been noted that this known solution, however, has considerable drawbacks.

In the first place, the continuous mechanical stresses the O-ring is subject to cause the progressive deterioration of the ring itself, the anti-noise function whereof tends to decrease progressively. A further and even more considerable drawback results from the fact that the wear of the anti-noise ring modifies the useful travel of the injector mobile core, changing the performance thereof over time and consequently causing faults in the dosing of fuel of the vehicle engine. Description

The object of this invention is to obviate the disadvantages mentioned hereinabove.

More in particular, the object of this invention is to provide an improved injector for gas systems, especially suitable for dosing

and distributing fuel in alternative endothermic engines totally or partly fed with methane gas or LPG, provided with means suitable on the one side to carry out the required anti-noise function and on the other side such as to withstand high mechanical stresses over time.

A further and consequent object of the invention is to provide an injector as defined above wherein said anti-noise means exclude possible faults in the fuel dosing. A further object of the finding is to provide the users with an improved injector suitable for ensuring a high level of resistance and reliability over time, also such as to be easily and inexpensively constructed.

These and yet other objects are achieved by the improved injector for gas systems of this invention, suitable for dosing and distributing fuel in alternative endothermic engines, totally or partly fed by methane gas or LPG and associated to a ramp wherein a common gas storage container is formed, comprising a reel wherein a sleeve is centrally arranged, which seats a mobile core or piston axially moved by an electromagnet and arranged adjacent the lower end of an overlying fixed core and which is characterised in that a small ring of elastomeric material with quadrangular section is interposed between the upper end of said piston and the fixed core.

Brief Description of Drawings

The construction and functional features of the improved injector for gas systems of this invention shall be better understood from the following detailed description, wherein reference is made to the annexed drawing tables showing a preferred and non-limiting embodiment thereof, wherein: figure 1 shows a schematic front view of a plurality of injectors according to the invention, associated to a ramp, known per se, wherefrom the fuel is dosed and delivered to the engine by the injectors themselves; figure 2 schematically shows a longitudinal section along line A-A of figure 1 ; figure 3 shows an enlarged detail of figure 2, highlighting the closed condition of the mobile core or piston of the injector of this invention; figure 4 shows a further enlargement according to figure 2, highlighting the open condition of the same mobile core; figure 5 shows a schematic perspective view of the mobile core or piston of the injector according to the invention; figure 6 shows a schematic exploded view of the same mobile core; figure 7 shows a schematic plan view of one of the components of the mobile core of figures 5 and 6, in particular of a small ring with quadrangular section.

figure 8 shows α cross section along line A-A of figure 7 of the same component; figures 9 and 10 show, similarly to the enlarged details of figures 3 and 4, as many longitudinal section views of the mobile core and of a part of the fixed core. Disclosure of Invention

With reference to the above figures, the improved injector for gas systems of this invention, globally indicated with 10 at figures 1 and 2, is typically associated with other identical units to a ramp 12, known per se, which serves as common container for the storage of the gas to be dosed and distributed to the various cylinders. Said injector comprises a reel 14, for example with substantially rectangular plan, wherein a sleeve 20 is centrally arranged which sears a mobile core or piston 16, axially moved by an electromagnet 18.

The lower end of piston 16 is defined by a plate 22 integral to a stem 24 elastically supported by a helical spring 26; the lifting of the plate 22 opens the passage of the gas that from ramp 12, and in particular from the common storage container 28 of the ramp itself, flows into a duct 32 to feed the cylinder associated to the respective injector.

The lifting of the mobile core or piston 16 makes the upper end 38 of the latter abut on the fixed core or part, indicated with 30 by the electromagnet, causing the noise.

According to the invention, α washer or small ring 34 of elastomeric material, for example nitrile butadiene rubbers or perfluoroelastomers such as NBR, HNBR or FKM (Viton), with quadrangular section, illustrated in detail at figures 7 and 8 is arranged between the two metal surfaces defined by the upper end of the piston 16 and by the lower end of the fixed core 32. Said ring 34 is advantageously seated in a complementary annular seat 36 obtained at the upper end 38 of the piston 16, wherefrom it protrudes by an extent approximately comprised between 0.10 mm and 1.00 mm.

In the exemplary embodiment at the figures, the small ring 34 has a square section, but such section may be different, that is, rectangular, with dimensions comprised between 0.5 and 2.0 mm as regards the width, and 0.5 and 3.0 mm as regards the height; the inner diameter of the washer or ring 34 is advantageously comprised between 3 and 6 mm. As schematised at figures 9 and 10, which respectively show the piston 16 in lowering and lifting conditions similarly to figures 3 and A ₁ as an alternative the ring 34 can be arranged in a complementary seat obtained at the lower end of the fixed core 32, in any case always remaining interposed between the two aforementioned metal surfaces.

Through experimental checks carried out by the applicant it has been found that using the small ring or washer 34 with

quadrangular section instead of the traditional O-ring ensures both the optimum reduction of noise and the retaining of constant performance of the injector over time, due to the considerable increase of the surface of absorbing material that acts as bearing; faults in dosing the fuel are thus prevented, also thanks to the negligible wear the wide surface of the small ring 34 subject to mechanical stresses is subject to. Even if the invention has been described with particular reference to an embodiment thereof, made by way of a non- limiting example, several changes and variations will appear clearly to a man skilled in the art in the light of the above description. This invention therefore is intended to include any changes and variations thereof falling within the spirit and the scope of protection of the following claims.