ITPZ990004A1 - MULTI-INJECTOR SYSTEMS. - Google Patents

Description

MULTI-INJECTOR SYSTEMS

The multi-injector system arises from the need to better manage the laws that regulate the injection, the pre-injection (s) and possibly the post-injection (s), in order to improve the combustion process and, consequently, to reduce the polluting masses. .

Thanks to the possibility of offering greater degrees of freedom, the aforementioned system makes it possible to better optimize, compared to current systems, the process of feeding the fuel into the combustion chamber, to the benefit of combustion efficiency and the quality of the exhaust gases.

There are many possibilities and applications that are offered by the aforementioned system and some examples will be illustrated below, it being understood that a great variety of combinations are possible.

DESCRIPTION:

The multi-injector system is composed of any injection system with the particularity of having two or more injectors which can also be, depending on the case, different from each other.

The mechanical or, preferably, electronic management of the injectors allows to obtain degrees of freedom, in the laws of injection and pre-injection, far superior to single-injector systems.

In what follows, even when we refer to two injectors, it is understood that it is still possible to use more than two.

APPLICATION TO DIRECT INJECTION DIESEL ENGINES:

It is known that, due to the different needs of the engines, depending on the characteristic parameters such as load, rotation speed, temperatures, pressures, etc., it is difficult to manage the fuel pre-injections with respect to the main injection and that the more finely and homogeneously the fuel is injected into the combustion chamber, the better the subsequent combustion will be.

The proposed system allows to release the pre-injection (s) from the main injection as the two or more injectors can be managed independently and therefore the pre-injection relating to one injector can be carried out independently of the main injection of the other; for example, the pre-injection relating to an injector can be completed completely before or it can be done so that the end of it overlaps the beginning of the primary injection of the other injector.

The main injection, being able to carry out it with more injectors, provides the possibility of better mixing the fuel with the comburent both because each injector has to inject a smaller quantity of fuel, resulting in finer atomisation, and because the injection points are located in different positions, both because the laws governing the individual injections may be different from each other (injection start, quantity, etc.); furthermore, all this favors the use of significantly lower operating pressures with a consequent reduction in costs and greater reliability of the injection system.

Table 1/2 shows an example of which could be the injection law obtained with two injectors and in which the dashed lines respectively represent the injection laws of two injectors, while the continuous one represents the sum of the single injections; Fig. 1 shows that the pre-injection of one injector overlaps the main injection of the other and it is also noted that an injector performs only the pre-injection; Fig. 2 shows the single injection laws and the resulting injection (sum of the two single injections).

Another objective achievable with the double injector may be to allow Diesel engines to circumvent the problems related to the inertia of the injection system and therefore to reach, compatibly with the inertia forces of the engine, significantly higher rotation speeds compared to systems. traditional; this is possible by making the two injectors work alternately, in the sense that each injector injects its own dose of fuel once every four turns of the handle. Therefore, the engine rotation speed, for the injection system, could be even double the maximum rotation speed allowed by the current systems.

From what has been said it is evident that the multi-injector solution allows ample freedom in the choice of system management criteria and it is also evident that it is possible to pass from one management criterion to another, during engine operation, by managing the transition phase. in the most appropriate way; this is also valid for the management systems described below.

APPLICATION TO COMMAND IGNITION ENGINES

It is known that the efforts of researchers, regarding the evolution of spark ignition engines, are aimed at the evolution of direct injection engines and among the problems encountered are the difficulties in obtaining a uniform and finely distributed mixture. The use of the double injector can bring considerable benefits to the system and can be conceived in many ways, but we will examine only two:

a first system is to position the injectors in such a way that the nozzles face directly into the combustion chamber

a second system is to ensure that one overlooks the combustion chamber while the other overlooks the intake duct

The advantages deriving from the first system lie in the fact that the injectors, being two or more, better homogenize the charge.

One of the two injectors could be entrusted with the task of injecting a certain quantity of fuel, just before the spark strikes, near the ignition area of the combustion in such a way that a sufficiently carburized mixture is present around the spark plug; in this way, lean mixtures could also be used because the injection made near the spark plug makes the mixture greasy only in that area, favoring the ignition of combustion;

One could also think of the possibility of carrying out a small injection (post-injection) during the first phase of combustion so that the fuel particles, which will be vaporized when crossing the burnt zone, trigger micro-combustions in areas that are still unburned and far from the front. of flame; the effect would be _ to speed up combustion and remove the danger of detonation. An example of how it could be; <'> as an indication, one of the possible laws of injection is shown in fig. 3 tav <'> 2/2 in which an injector (continuous line) performs both the injection during the aspiration phase that the post-injection (the latter could be missing 6 be carried out by another injector), while another injector carries out a pre-injection possibly near the spark plug. - A use of the second system could be to use the injector located on the suction duct for the formation of <'> A very lean (but homogeneous) mixture while the injector located on the head is given the task of greasing the mixture in correspondence of the priming zone and possibly to carry out a post-injection (this latter task could be performed by another injector).

Fig. 3 table 2/2 shows an injection law in which <'> an injector makes an injection into the intake duct (continuous line) (as occurs for traditional engines) <'> while another injector, located on the cylinder head, <'> carries out the pre-injection (dotted line); the figure also shows a post-injection (dash-dot line) which can be performed both by the same injector that has just carried out the pre-injection and by another injector. .

Another system could be to do. inject a certain quantity of fuel from an injector placed in a sort of pre-chamber in which the spark plug is also housed, and another injector makes the injection into the combustion chamber (there could also be an injector on the intake duct).

Both systems can be exploited by both 4-stroke and 2-stroke engines.

Claims (13)

CLAIMS: 1) Injection systems and their management; these systems are characterized by being made up of more than one injector per cylinder. 2) Injection system as per claim 1); where the injectors face; in the combustion chamber. 3) Injection system as per claim 1); in which one injector faces the combustion chamber, while the other faces the intake duct. 4) Injection system as per claim 1); in which one injector faces the main combustion chamber while the other faces a side chamber connected to the main combustion chamber. 5) Injection system as per claim 1); in which the injectors are positioned in a lateral chamber connected to the main combustion chamber. 6) The injection systems described in claims 1), 2), 3), 4), 5) may consist of several injectors, not necessarily all the same. 7) Injection system consisting of a mix of the systems described above. 8) The law of injection of injection systems, as per claim 1), 2), 3), 4), 5), 6), 7), is the sum of the single injection laws relating to single injectors or groups of themselves. 9) Injection system as per claim 1), 2), 3), 4), 5), 6), 7), 8); referring, for simplicity, to only two injectors, the injection management can be such as to make the main injection, the pre-injection (s) and possibly the post-injection take place alternately; in other words, each injector makes a complete injection once every two cycles. 10) Injection system as per claim 9); in which the main injection takes place alternately as well as the pre-injection (s) with the difference that the pre-injection (s) of an injector takes place in the same cycle in which the complete injection cycle of the other occurs; in other words, even the injector that should be at rest in a given cycle can intervene with pre-injections or mini injections. 11) Injection system as per claim 9), 10); in which the injectors are more than two or more than two groups, in this case the single injections will follow each other with a frequency depending on the number of injectors or the number of injector groups. 12) Injection system as per claims 9), 10), 11); the pre-injection (s) relating to an injector, or group, is released from the main injection (s) of the other injector (s) and vice versa. 13) Injection system as per claims 1), 2), 3), 4), 5), 6), 7); the pre-injection relating to an injector, or group, can be overlapped with the main injection of the other injector / s. . , 14) Injection system as per claim 3), 6), 7); the injection (s) and / or pre-injection (s) of the injector (s) placed on the intake duct are preferably carried out during the intake phase, while those directly facing the combustion chamber follow one of the laws injection units described in claims 8), 9), 10), 11), 12) and 13). 15) Injection system as per claims 1), 2), 4), 5), 6), 7); the management of direct injection for positive ignition engines can be such as to allow one of the two or both injectors to inject the fuel during the intake and compression phase and to carry out, both or only one of them, a post-injection just before or around the moment when the spark strikes, ' 16) Injection system as per claims 1), 2), 4), 5), 6), 7); the management of direct injection for spark ignition engines can be such as to allow an injector to inject fuel during the intake and compression phase, while another injector injects a certain amount of fuel, near the spark plug, before or at the moment when the spark strikes; the latter can also inject during the suction and compression phase. 17) Injection system as per claims 1), 3), 4), 6), 7); injection management for positive ignition engines, in which the injector located on the intake duct injects a part of the fuel while the injector that faces the combustion chamber and / or the pre-chamber injects the remaining quantity of fuel during the suction and compression phases and / or, near the spark plug, before or around the instant in which the spark strikes. 18) Injection system as per claims 17); with the difference of having more than one injector facing the combustion chamber and / or the pre-chamber as per claims 1), 2), 4), 6), 7), and whose management is like that of claim 16) and / or more injectors located on the intake duct. 19) The electronic management of the injectors allows you to manage the engine, with one of the systems described in the previous claims or with a mix of them, switching from one to the other according to the characteristic parameters of instantaneous operation of the engine, detected by means of special sensors; in other words, the same engine can be managed by one of the aforementioned management systems and then switch to another as soon as the motion conditions change, managing the transition from one system to another in the most appropriate way. 20) Although some management methods have been claimed, it is intended to extend the claims to any management method linked to the multi-injector system.