"Improved ramp for injectors" Technical Field

This invention relates to an improved ramp for injectors.

More in particular, this invention relates to an improved ramp for injectors that carry out the dosing and distribution of fuel in alternative endothermic engines totally or partly fed with methane gas or LPG (Liquid Petroleum Gas).

Background Art

It is known that injectors for gas systems of the above motors may be single or mounted on a ramp; in the first case, the fuel typically enters from the top of the body and exits from the bottom one, similarly to what usually happens in injectors suitable for feeding fuel or gas oil.

In the case of feeding gaseous fuels, very often the methane gas or the LPG enters into a storage volume, common to the three, four cylinders of the engine or multiples thereof and from such container it is dosed and delivered to the cylinders themselves by means of the controlled opening of the various injectors.

With particular reference to this second type, conventionally defined as "injector rails", various solutions are known for making the ramp or the rail that makes up the gas storage container. These different solutions generally envisage the use of aluminium drawn bars, suitably processed for obtaining holes, cavities and fluid communication and passage openings thereon.

It has been noted that this known embodiment implies considerable drawbacks.

In the first place, the use of a metal bar for making the ramp gives rise to uselessly high weight and volume component; considering the current and increasingly felt construction requirements, that tend to compact and lighten the propulsion units as much as possible, such solution is anything but optimum.

A further drawback of known ramps at issue relates to the gas flow sections therein; especially between the common duct extending longitudinally and the parts that receive a respective injector, at present it is not possible to obtain high processing tolerances, with the consequence that considerable load losses may be seen and flow unevenness in the moving fluid mass (gas). Moreover, the considerable aluminium mass and the unevenness in the thickness of the walls causes relative slowness in achieving and keeping the operating temperature constant inside the injector, a very important parameter for keeping maintaining the gas density constant, in particular for LPG's which at the usage pressures and with low temperatures, tend to liquefy causing sure vehicle malfunctions.

According to another known embodiment, the ramp is composed of a moulded body of plastic or metal material wherein the electromechanical components made up of the injectors are buried and delimited by a single flange. However, also this solution has the considerable drawback of larger overall dimensions that could affect

the mounting position in the engine seat, deviating it from the technically ideal one, as well as the further drawback if maintenance operations are required on the injectors, due to the greater complication in the relative assembly/ removal operations. 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 ramp for injectors, in particular for injectors suitable for dosing and distributing methane gas or LPG in alternative endothermic engines of particularly moderate weight and volume. A further object of the invention is to provide an improved ramp for injectors provided with minimal processing tolerances at the holes, cavities and fluid passage openings. A further and consequent object of the invention is to provide an improved ramp for injectors suitable for considerably reducing load losses and flow unevenness of the moving fluid mass. Last but not least, an object of the invention is to provide an improved ramp for injectors with even thickness wall for quickly achieving and keeping the operating temperature constant inside the injector, consequently for keeping the gas density constant. A further object of the finding is to provide the users with an improved ramp for injectors suitable for ensuring 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 ramp for injectors of this invention which, especially for injectors suitable for dosing and distributing fuel in alternative endothermic engines totally or partly fed by methane gas or LPG, made of aluminium, alloys thereof or other suitable material, is essentially characterised in that it comprises a plurality of aligned and equally spaced supports for each injector, composed of cup bodies connected to one another and communicating through integral tubular sectors with circular section, said ramp being made by hot moulding. Brief Description of Drawings

The construction and functional features of the improved ramp for injectors 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 the improved ramp for injectors of this invention, by way of an example with four units for as many injectors; figure 2 shows a schematic bottom view of the same ramp; figure 3 shows a schematic plan view of the same ramp; figure 4 shows the schematic view from one of the heads of said ramp; figure 5 is a longitudinal section view along line A-A in figure 4 of the same ramp;

figure 6 shows a schematic front view of the improved ramp of this invention associated to the respective injectors; figure 7 shows a schematic side view of the same ramp with injectors of the previous figure; figures 8 and 9 schematically show as many perspective views from the front side and from the back side of the ramp of figures 1 to 4; figure 10 shows a schematic perspective front view of a ramp provided by way of an example with three units for as many injectors. Disclosure of Invention

With reference to the above figures, the improved ramp for injectors of this invention, globally indicated with 10 at figures 1 and 8, comprises a plurality of aligned and equally spaced supports for every single injector composed of cup bodies 12, substantially with upturned truncated-cone shape, connected to one another and communicating through integral tubular sectors 14. The cup bodies 12 may be provided in a number of four, as per figures 1 to 3, 5, 6, 8 and 9, or in a number of three, as per figure 10; in the first case, the ramp 10 is suitable for engine heads with four cylinders or multiples thereof, whereas in the second case it is used for three cylinder engines or multiples thereof. The tubular sectors 14 that connect the bodies 12 preferably have a circular section. The opposite ends or head of the ramp 10 define respective collars 16 typically suitable for receiving a closing cap 18 on one end and a

conventional union 20 for fuel flow feeding or suction on the opposite end.

The bottom base with smaller diameter of the cup bodies 12 extends towards the back front of an integral pierced base 22 of limited height, which connects to the base with the respective tubular sector 14 and forms the coupling zone for the known nozzles, not shown. Advantageously, the ramp 10 thus formed and comprising the cup bodies 12 with base 22, the tubular connecting sectors 14 and the end collars 16 is made in a single body of aluminium by hot moulding and subsequently it is subject to sandblasting or the like for eliminating burrs and making the surface even. Afterwards, mechanical precision processes are carried out on the ramp 10 in a substantially known manner for obtaining threads, as well as holes and cavities that carry out the gas passage from the inlet to the outlet towards the engine, such as for example the longitudinally extended hole indicated with 24 at figure 5 and the openings created starting from the top exposed front of the cup bodies 12, indicated with 26 and suitable for receiving a part of the injectors, per se known and schematised with 28 at figures 6 and 7. As can be seen from the attached figures, the cup bodies 12 protrude on the front side relative to the tubular connecting sectors 14 wherealong the longitudinal hole is formed 24 which extends in the heads 16 crossing the cup bodies 12; on the opposite back side, in central position, one or more of the tubular sectors 14 is at least partially built in a coating that forms an integral plate 30 with planar

development; said coating, which extends in the direction of the cup bodies 12 both upwards and downwards, is obtained integrally with the rest of the body and determines a strengthening of the ramp 10 as a whole, but without protruding from the ramp itself and prevents possible deformations thereof both in the moulding step and during the subsequent mechanical processes. At the same time, the plate 30 with planar development composed of the above coating, defines a surface advantageously suitable for receiving plates with reference data of the product and/or stamping. Further reinforcing ribs 32 are developed in horizontal direction on the front side of the ramp 10, along the tubular sectors 14 arranged between the cup bodies 12. On account of the structure described above, the ramp 10 of this invention allows optimising weights and overall dimensions, both due to the upturned truncated-cone shape of the cup bodies 12 the injectors 28 are associated to, and due to the tubular sectors 14 that, suitably sized, connect said bodies 12 leaving lowered zones on the front side free from excess material.

The localised strengthening from the back side that makes up the plate 30, moreover, does not cause any projections, and thereby further obstructions, relative to the various required parts of the ramp 10.

Theoretical and practical verifications carried out by the applicant have allowed determining that, compared to the similar and traditional ramps obtained from bar, the improved ramp of this finding has a reduced weight of an extent comprised between 55 and

60%, this means a weight reduced from about 150 grams to 60 grams for the ramp with four units, and from about 110 grams to 50 grams for the version with three units.

Moreover, the moulding construction of the ramp 10 gives rise to a significant reduction of the geometrical tolerances of the outer body relative to the drawn bars; as a consequence, also the tolerances on the distances between the centres of the holes and cavities for fluid passage are reduced, with considerable improvements in the width and in the constancy of the gas passage sections and consequent reduction of load losses, as well as of the unevenness of the moving mass flow.

Moreover, thanks to the reduction of the overall mass and to the improved thickness evenness, the ramp object of the invention allows quicker achievement of the operating temperature and higher temperature evenness in all of the body points.

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.