FUEL INJECTION SUPPLY SYSTEM FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINE

Abstract: A fuel injection supply system for an internal combustion engine provided with an even number more than 4 inclusive of cylinders; the first intake manifold (2) is connected to the first cylinder group comprising one half of the cylinders and the second intake manifold (3) is connected to the second cylinder group comprising the other half of the cylinders; a passage collector member (8) is provided which collects the intake pas­ sages to as to communicate the intake ports of the first and second manifolds (2, 3) with each other; and the first fuel supply device (4) is disposed at the converging portion of the first intake manifold (2) and the second fuel supply device(5) is disposed at the converging portion of the second intake manifold (3).

Description: FIELD OF THE INVENTION AND RELATED ART STATEMENT The present invention relates to a fuel injection supply system for an internal combustion engine in accordance with the precharacterizing part of claim 1. Such a fuel injection supply system is known from EP-A-0156371 being a prior art document according to Art. 54(3) EPC. Known fuel injection systems can be classified in multi-point fuel injection systems having one fuel injection valve for each cylinder and single-point fuel injection systems having only one fuel injection valve mounted to an intake manifold on the upstream side of its converging portion. The mult-point fuel injection system, however, suffers from a disadvantage that its costs become rather high since each cylinder requires its own fuel injection valve. Besides, another drawback thereof is that this system injects fuel close to the intake valve of the engine so that, when fuel has entered the combustion chamber, fuel density distribution within the chamber is easy to loose its uniformity, thus necessarily causing worsened combustion, lowered thermal efficiency and deteriorated economy of fuel expenses. On the other hand, the single-point fuel injection system is relatively lower in its cost since only one fuel injection valve suffices for it. This system, however, also suffers from its inherent drawback in that it is prone to give rise to unbalanced air-fuel ratios among respective cylinders, which tends to result in lowered engine power, deteriorated fuel economy and worsened operating performances as well. The fuel injection supply system which is known from the EP-A-156371 is formed as one unit and mounted between both intake manifolds so as to connect those to each other. Further, the atomizer rings are driven by one common vibrator unit which is disposed between the intake manifolds. In this known system a mounting where the injector valves lie on one side of the intake manifold and the atomizing means lie opposite thereto and are coaxially mounted, is not possible. Further, a separate adjustment of the characteristics of the atomizers in each intake manifold is not possible. It is also impossible to mount the same unit on other type engines having different distances between the intake manifolds. SUMMARY OF THE INVENTION: The object of the present invention is to provide a fuel injection supply system which completely eliminates all the drawbacks inevitable in both the conventional multi-point and singel-point fuel injection systems noted above, achieves versatility for the mounting of the fuel supply elements, reduces the number of fuel injection valves, assures uniform fuel density distribution prior to entry of the fuel/air mixture into the combustion chamber and prevents fuel from depositing at the inner wall of the intake manifold. The above object is solved by the features of claim 1. The dependent claims 2 to 6 characterize advantageous developments thereof. When compared with prior art multi-point fuel injection systems, the number of the fuel injection valves according to the present invention is reduced so that the overall cost is reduced. Additionally, fuel injected from the fuel injection valves is caused to be atomized instantaneously with the aid of the atomizing devices so that an uniformly distributed density of fuel can easily be achieved with respect to air. Due to the disposition of the properly dimensioned length of the intake manifolds extending from the fuel injection valves up to the combustion chamber, an uniform fuel density distribution relative to air is assured prior to entry of fuel into the combustion chamber, which contributes to provision of effects such as betterment of combustion, improvement in thermal efficiency and economy of fuel consumption. Moreover, the present invention provides a further effect that, since half the total cylinders are collectively dealt with by means of one set comprising an intake manifold, a fuel injection valve, an atomizing device and a throttling valve, air-fuel ratio imbalance between the respective cylinders can be made smaller in comparison with that in a single-point fuel injection system. In the case where four cylinders are in use, for instance, the first and second cylinders and the third and fourth cylinders are separately grouped to constitute respective packages and independently dealt with so that air-fuel ratio imbalance between the respective cylinders is, if any, in smaller degree than where all cylinders are dealt with as a single package, and in case that imbalance of air-fuel ratios should occur, it can easily be remedied only by modifying the configuration, dimension or the like of the related passages. More particularly, since only two cylinders are dealt with as a package, such imbalance which has occurred between said two cylinders can be eliminated with extreme easiness merely by altering passage resistance within the intake passage leading to one of the two cylinders. Furthermore, since fuel injected from each fuel injection valve is atomized almost at the central portion of each intake passage, the fuel is prevented from sticking to the inner wall surface of the intake manifold, which results in improved responsiveness and also improved operating performance. In addition, due to the fact that each intake passage exending from its related intake manifold up to the fuel supply means is arranged to take an approximately horizontal posture, air stream is rendered smooth and this in turn helps achieve a further improvement in responsiveness and operating performance. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a partially sectioned block diagram illustrating a preferred embodiment of a fuel supply system with a fuel atomizing device according to the present invention; Figs. 2 and 3 are vertically and horizontally sectioned views of essential portions of a fuel supply means according to the present invention; and Figs. 4 to 6 inclusive are block diagrams partially showed in vertical sections respectively illustrating other modified embodiments according to the present invention DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Now, the invention will be explained with reference to its exemplary embodiments in the following. Referring to Fig. 1, there is shown an internal combustion engine 1 comprising four cylinders of which a pair of the first and second cylinders constitute the first cylinder group connected to the first intake manifold 2 and another pair of the third and fourth cylinders constitute the second cylinder group connected to the second intake manifold 3. The intake manifolds 2, 3 are connected, upstream of converging portions 2a, 3a thereof, respectively to the first and second fuel supply means 4, 5 which, in turn, are connected to a passage collector member 8 respectively by way of passages 6, 7 extending in parallel to each other from said collector member 8. Upstream of the passage collector member 8 is disposed a throttling valve 9, and further upstream of said throttling valve 9 are provided an air flow meter 11 and an air cleaner 12 in sequence. As can be seen from Figs. 2 and 3, the first and second fuel supply means 4, 5 are constructed such that there is provided an atomizing device 15 mounted so as to have its tubular hollow vibrating piece 14 positioned approximately in the central portion of an air intake passage 13, said tubular hollow vibrating piece 14 being formed with a transverse bore 14a through its side wall, and a fuel injection solenoid valve 16 is provided at a location so close to said transverse bore 14a as to enable fuel to pass therethrough. The fuel injection solenoid 16 is arranged to inject fuel in the direction almost at right angles to the axis of said tubular hollow vibrating piece 14. Besides, from the first and second intake manifolds 2, 3 to the first and second fuel supply means 4, 5, the respective air intake passages are positioned to extend almost horizontally. With the arrangements described above, fuel can be delivered to each fuel injection valve 16 by means of a fuel pump 18 form a fuel tank 17 through a fuel filter 19 and a damper which is adapted to take up possible fuel pressure pulsations and fuel can be returned through a fuel pressure regulator 21 to the fuel tank 17. In this first embodiment of the invention, the valve opening duration for the fuel injection valve 16 is determined such that the amount of fuel delivered should correspond to the value of the intake air bass flow measured at the intake flow meter 11 divided by the number of revolutions. The respective fuel injection valves 16 for the fuel supply means 4, 5 may be arranged to open either concurrently or in synchronized relation with associated air intake valves for the respective cylinders. The controlling for such valve operations can be accomplished by any type of fuel injection system commonly practiced hitherto. Therefore, a particular explanation of it will be omitted. The atomizing device 15 incorporated in the embodiment is of a construction wherein the tubular hollow vibrating piece 14 is caused to oscillate by ultrasonic waves and fuel injected out of the fuel injection valve 16 is atomized by such ultrasonic oscillations instantly when it impinges against the tubular hollow vibrating piece 14. Fig. 4 illustrates a modified embodiment of the present invention in which the direction of the intake passage extending from the intake manifolds 2, 3 to the air cleaner 12 has been changed as a result of a modified location of the passage collector member 8. This configuration lends itself to easier arrangement of related components yet providing the effect similar to that described above. Furthermore, by arranging the parallel passages 6, 7 leading to a passage collecting portion 8a such that the latter is disposed over the former as can be seen in Fig. 4, an additional effect is obtained which contributes to suppression of reversed fuel flow caused by back fire and blow back phenomina from the engine. Referring to Fig. 5 next, there is shown another modified embodiment of the invention which differs from the first embodiment only in that, instead of the single throttling valve 9 disposed upstream of the passage collector member 8 in the first embodiment, the first and second throttling valves 22, 23 are disposed just upstream of the first and second fuel supply means 4, 5 respectively. Both the throttling valves 22, 23 are mutually synchronized when they are caused to operate. Also, it is possible in this embodiment to change, as is shown in Fig. 6, by the location of the passage collector member 8, the direction of the intake passage extending from the intake manifolds 2, 3 to the air cleaner 12 while assuming the same effect as in the case shown in Fig. 4 relative to the first embodiment in Fig. 1.

Claims: A fuel injection supply system for an internal combustion engine having an even number of four or more than four cylinders, an intake throttle valve or valves and a fuel supply means, comprising a fuel injection valve and an atomizing device halfway on an intake passage extending between each combustion chamber intake port and an air cleaner outlet, the first intake manifold (2) being connected to a first cylinder group comprising one half of all the cylinders and the second intake manifold (3) connected to a second cylinder group comprising the other half of the cylinders; said atomizing device comprising a pair of atomizing means (14, 15) each having a cylindrical vibrator diposed concentrically in the center of the first and second intake manifold (2, 3); wherein the first fuel supply means (4) are disposed at a converging portion of the first intake manifold (2) and the second fuel supply means (5) are disposed at a converging portion of the second intake manifold (3); wherein said first and second fuel supply means (4, 5) comprise a pair of tubular members which are disposed separately from one another and each forming a part of the first and second intake manifold (2, 3); said atomizing means are mounted separately from one another on an outer periphery of each tubular member; and said injector valves are mounted separately from one another on the outer periphery of each tubular member so that fuel is injected and supplied into the interior of each cylindrical vibrator. A fuel injection supply system as defined in claim 1, characterized in that the intake passages in the first and second intake manifolds (2, 3) and in the first and second fuel supply means (4, 5) are disposed almost horizontally. A fuel injection supply system as defined in claim 1, characterized in that said throttle valve (9) is located upstream of said passage collector member (8). A fuel injection supply system as defined in claim 1, characterized in that said throttle valves (22, 23) are located in passages between said passage collector member (8) and each of said first and second fuel supply means (4, 5). A fuel injection supply system as defined in claim 2, characterized in that the direction of the intake passage changes by the disposition of the passage collector member (8). A fuel injection supply system as defined in claim 1, characterized in that the fuel injection valves (16) are adapted to inject fuel in a direction almost perpendicular to the axis of the cylindrical vibrator (14).

Inventors: TAKAYAMA, TERUO, YAMAUCHI, TERUO
Applicants: HITACHI, LTD.
Application year: 1986
Main classification: F02M27
IPC codes: F02M27, F02M35, F02M69, F02M29