Multi-Cylinder Fuel Atomizer for Automobiles

The present invention relates to a fuel atomizer for automobiles which can cope with fuel supply for multi-fuel and multi-point injection.

Heretofore, fuel supply devices for automobiles have been broadly classified into the two sorts of a carburettor and a fuel injector. The former adopts a continuous fuel measuring system, while the latter an intermittent fuel measuring system, and they are installed on multicylinder engines.

With the fuel supply devices, however, the diameters of fuel liquid drops generated are not uniform and very small. Therefore, the uniform distribution of fuel to the respective cylinders of the multicylinder engine cannot be achieved, and fuel to be supplied to the respective cylinders becomes ununiform. The resulting ununiform fuel causes a stable combustion and induces the degradations of an exhaust purification efficiency and a combustion efficiency, which form factors for increasing fuel consumption and a harmful exhaust level. Moreover, in using various sorts of fuel and lowering the grade of fuel recently, the situations cannot be coped with only the fuel supply system based on both the above systems, and a fuel supply system having novel atomization means is eagerly requested.

Meanwhile, from the standpoint of purchasing an automobile, it is desirable that the engine power is high and that the automobile is inexpensive. In this regard, the fuel injector has injection valves for the respective cylinders and employs a suction inertia utilizing arrangement in which a suction pipe is lengthened. Therefore, this system is effective from the viewpoint of enhancing the power, but unfavorably a high cost is incurred on account of a complicated structure. On the other hand, the carburettor system is a system in which fuel measuring portions are concentrated on one point. Although it is simple in arrangement and low in cost, it has the problem that the structure of a suction pipe has a shape incapable of utilizing suction inertia, so the enhancement of power cannot be expected.

For these reasons, there has recently been proposed the technique of atomizing fuel by the use of the ring vibrator of an ultrasonic vibration system as described in the official gazette of Japanese Laid-open Patent Application No. 53-140415. With the ring vibrator, however, the fuel must be concentrated on one point. This leads to the problems that the technique as it is cannot be applied to a multi-point fuel injection type engine, the scope of use thereof being restricted to carburettor type and single-point fuel injection type engines, and that the enhancement of power cannot be expected.

An object of the present invention is to provide a multi-cylinder fuel atomizer for automobiles which is also applicable to a multi-point injection type engine, and which eliminates astable combustion in respective cylinders even with fuel of low grade and can attain high power with an inexpensive arrangement.

The present invention is so constructed that an electromechanical transducer is disposed between a concentrated cylinder for suction and respective suction pipes, while a horn ring vibrator which is fixed to an end of the electromechanical transducer and which is partly exposed to the respective suction pipes is disposed, fuel being injected to an inner wall of the horn ring vibrator so as to atomize the fuel and then introduce the atomized fuel to respective cylinders.

According to the present invention, the construction specified above brings forth the effects that even the respective cylinders of a multi-point fuel injection type engine can be fed with the atomized fuel without the astable combustion thereof and that high power can be attained with the inexpensive construction. A further effect is that the fuel cost during the idle running of little suction inertia can be reduced.

FIG. 1 is a general arrangement view showing an embodiment of an engine system to which the present invention is applied;

FIG. 2 is a view showing an example of the arrangement of ring vibrators which are installed in a suction pipe;

FIG. 3 is a view showing another example of the arrangement of the ring vibrators installed in the suction pipe;

FIG. 4 is a view showing a ring vibrator mounting structure to which a fuel measuring system is added;

FIG. 5 is a vertical sectional view corresponding to FIG. 4;

FIG. 6 is a view showing an example of the structure of the ring vibrators;

FIG. 7 is a view showing another example of the structure of the ring vibrators;

FIGS. 8(a)-8(c) are views showing an example of the structure of a horn;

FIG. 9 is a vertical sectional view corresponding to FIG. 8(b);

FIGS. 10(a)-10(c) are views showing another example of the structure of the horn;

FIG. 11 is a vertical sectional view corresponding to FIG. 10(b);

FIGS. 12(a) and 12(b) are a sectional view and a plan view, respectively, showing a structure for connecting the ring vibrator and the horn;

FIGS. 13(a)-13(c) are views showing still another example of the structure of the horn;

FIG. 14 is a vertical sectional view corresponding to FIG. 13(b);

FIG. 15 is an arrangement view of essential portions showing a fourth embodiment of the present invention in which two fuel injection valves are installed;

FIG. 16 is a sectional view corresponding to FIG. 16;

FIG. 17 is an enlarged view of a part in FIG. 16;

FIG. 18 is a view showing another example of the ring vibrators; and

FIG. 19 is a sectional view corresponding to FIG. 19.

Now, the present invention will be described in detail in conjunction with embodiments.

FIG. 1 is a general arrangement view showing one embodiment of an engine system to which the present invention is applied.

Referring to the figure, air and fuel are imbibed from a suction pipe 6 by the opening and closure of the suction valve 2 of an engine 1, the mixture is ignited by an ignition plug 3 and burns, and power is transmitted to wheels (not shown). In this case, the ignition plug 3 is constructed so as to generate an electric spark in such a way that the signal of a crank angle sensor 5 is sent to a computer 20 and that a signal is applied to an ignition coil 4 at a necessary timing. Meanwhile, to the end of extending suction inertia, the suction pipe 6 is provided on its upper stream side with a concentrated cylinder 8 which has a volume not smaller than the capacity of one cylinder of the engine 1, and downstream of which independent suction pipes 6a, 6b, 6c and 6d are disposed and connected to respectively corresponding cylinders. The control of a suction air quantity for such suction system is executed by controlling the opening of a throttle valve 9. The situation of the throttle valve opening on that occasion is sensed by a throttle valve opening sensor 10, and it is applied to the computer 20 and stored here.

The concentrated cylinder 8 is located downstream of the throttle valve 9, and it is provided on its outlet side with suction pipe ports 11a, 11b, 11c and 11d which join to the respective suction pipes 6a, 6b, 6c and 6d. An ultrasonic vibrator 12 pertinent to the present invention is inserted in the portion of the suction pipe ports 11a, 11b, 11c and 11d.

The ultrasonic vibrator 12 has a structure in which ring vibrators 21a and 21b are fastened symmetrically with respect to the vibrator. The ring vibrators 21a and 21b are arranged in such a manner that the respective centers thereof agree with the center of the spacing between the suction pipe ports 11a and 11b and the center of the spacing between the suction pipe ports 11c and 11d. Upstream of the ultrasonic vibrator 12, a fuel injection valve 13 is mounted through the sideward outer wall of the concentrated cylinder 8. Fuel distribution nozzles constructed of tubules 22a, 22b, 22c and 22d are mounted on the fore end of the injection valve 13, and the fore ends of these nozzles 22a, 22b, 22c and 22d are arranged near the ring portions of the ring vibrators 21a and 21b. A fuel pressure regulator 14 is disposed unitarily with the injection valve 13. Fuel imbibed from a fuel tank 17 is introduced into the regulator 14 through a pump 18 as well as a fuel filter 19 and is regulated into a predetermined pressure. The pressure-regulated fuel is fed to the nozzles 22a, 22b, 22c and 22d, while surplus fuel is fed back to the fuel tank 17. An air quantity sensor 15 for measuring the quantity of air (which may be of any of the movable vane type, the hot wire type and the Karman vortex type) is mounted upstream of the throttle valve 9, and its output is sent to the computer 20 and is used for controlling the fuel injection timing and injection time period. Meanwhile, the combustion gas produced by the combustion passes through an exhaust pipe 7 and has the concentration of the residual oxygen thereof sensed by an oxygen sensor 16, whereupon it is emitted into the atmosphere through a catalyst as well as a muffler (not shown). The oxygen sensor 16 has the property that its output signal changes depending upon the surplus oxygen concentration of the exhaust gas. By utilizing this property, the concentration of the mixture imbibed by the engine 1 is presumed, and the valve opening duration of the injection valve 13 is controlled so as to secure fuel economy and exhaust purification as predetermined.

Here, the details of the structure in which the ultrasonic vibrator 12 is fixed by holding the ring vibrator portions in agreement with the suction pipe ports 11a, 11b, 11c and 11d will be described with reference to FIG. 2.

FIG. 2 shows the horizontal section of the concentrated cylinder 8 seen from the suction upper-stream side and taken horizontally. The concentrated cylinder 8 is provided with the four suction pipe ports 11a, 11b, 11c and 11d which are arrayed in series, and which are coupled to the respectively corresponding cylinders of the engine 1 through the independent pipes of the suction pipes 6a, 6b, 6c and 6d. The elements 23a and 23b of the ultrasonic vibrator 12 are disposed so as to lie in contact with the middle wall portion between the suction pipe ports 11b and 11c. The ring vibrators 21a and 21b coupled to these elements 23a and 23b are arranged so as to afford equal projection sections while extending over the suction pipe ports 11a, 11b and 11c, 11d, respectively.

Accordingly, when the fuel from the fuel injection valve nozzles 22a, 22b, 22c and 22d collides against the inner walls of the ring vibrators 21a and 21b of such structure, it is instantly atomized, whereupon it is carried by the suction air so as to be uniformly imbibed into the respective cylinders.

FIG. 3 is a sectional view showing an embodiment of the mounting structure of the ring vibrators in the case where the arrayal of the suction pipe ports is not series. The suction pipe ports 11a, 11b and 11c, 11d are respectively arranged in parallel, and the ultrasonic vibrator 12 is located at the intermediate position between the two rows of the suction pipe ports 11a, 11b and 11c, 11d. Moreover, vibrator horns 24a and 24b do not enter the suction pipe ports, so that the crosssectional areas of the respective suction pipes 6a, 6b, 6c and 6d for passing the air become equal.

Next, there will be explained a method of equally introducing fuel to the ring vibrators 21a and 21b.

FIG. 4 shows a practicable embodiment therefor. The fuel F injected from the injection valve 13 passes through fuel pipes 27a and 27b to reach nozzles 28a and 28b, and it is injected toward the inner walls or outer walls of the ring vibrators 21a and 21b, thereby to be atomized. Here, the ring vibrators 21a and 21b are respectively located intermediately between the suction pipe ports 11a and 11b and those 11c and 11d. Besides, both the nozzles 28a and 28b are bifurcated over the respective ring vibrators 21a and 21b, and the nozzle positions are selected so that the fuel may be injected into the respective suction pipe ports. In this case, the respective bifurcate nozzles should desirably be constructed so that the fuel injected therefrom may collide against the upper ends of the ring vibrators 21a and 21b or against somewhat lower positions.

FIG. 5 is a vertical sectional view of the portions in FIG. 4, showing the details of a spacer 25 for disposing ultrasonic vibrators 12a, 12b and a fuel passage plate 26 for measuring the fuel and injecting it for collision against the ring vibrators 21a, 21b. When the ultrasonic vibrators 12a, 12b are installed in the suction pipe portion as illustrated in FIGS. 4 and 5, it is possible to realize an atomizer for a four-cylinder engine, of which enhancement in power and a low fuel cost can be expected.

Next, the setup of the ultrasonic vibrator will be explained. FIG. 6 is a view showing an embodiment of the practicable setup thereof. In FIG. 6, electromechanical transducers 31a and 31b constructed of electrostrictive elements or magnetostrictive elements are respectively fastened to horns 33 and 34 by a bolt 32 with an anode 30 held therebetween. One horn 33 is provided with a flange 29 for fixation. The ring vibrators 21a and 21b are fixed to the distal ends of the respective horns 33 and 34 by silver brazing or welding in such a manner that their end faces are coplanar. The ultrasonic vibrator of such structure is fixed to the suction pipe by the flange 29, and a drive signal is applied across the flange 29 as a cathode and the anode 30.

FIG. 7 is a view showing another embodiment of the ultrasonic vibrator. The electromechanical transducers 31a, 31b and the anode 30 are held between horns 33 and 34 having independent flanges 29a and 29b, and are clamped and fixed by bolts 35a and 35b. The ring vibrators 21a and 21b are respectively fixed to the distal ends of the horns 33 and 34 by screws or welding. Here, a stay 36 is provided centrally. This stay 36 is unitary with the horn 33, and is provided as a guide for bringing the center axes of the transducers 31a, 31b, anode 30 and horns 33, 34 into agreement in case of assembling the ultrasonic vibrator. An insulator 37 (synthetic resin) is packed between the transducers 31a, 31b and the stay 36.

Now, the shape of the horn of the ultrasonic vibrator will be described in detail.

FIGS. 8(a)-8(c) show a practicable embodiment thereof. FIG. 8(a) is a view of the horn 34 seen from its front. The flange 29 is oblong, and has bolt holes 38a and 38b. In addition, the distal end of the horn 34 has a parallel portion 39 and a spigot joint boss 40 for fixing the ring vibrator 21a or 21b. On the other hand, FIG. 8(c) is a view of the horn 34 seen from its rear. A groove 41 is provided concentrically with the stay 36 so that, in bringing the electromechanical transducers 31a and 31b (refer to FIG. 7) into close contact, the center axes thereof may be prevented from deviating. FIG. 8(b) is a view of the horn 34 seen from its side. Besides, FIG. 9 is a sectional view of the horn 34 shown in FIG. 8(a). The joint part of a horn portion 34a with the flange 29 is rounded as indicated at numeral 42.

FIGS. 10(a)-10(c) show the horn 34 of a structure which is very similar to the structure illustrated in FIGS. 8(a)-8(c), but from which the stay 36 is removed. FIG. 11 is a sectional view of the horn 34 shown in FIGS. 10(a)-10(c). A recess 43 which is somewhat larger in diameter than the stay 36 shown in FIGS. 8(b) and 8(c) is provided in the groove 41. Such recesses 43 function as spigot joints in the case where the two electromechanical transducers (not shown) are held between the horns as shown in FIGS. 10(a)-10(c) and are unitarily assembled therewith.

FIG. 12(a) is a view showing a section in the case where the ring vibrator 21 has been added to the horn 34. A stiffening plate 43 is pressed in the spigot joint boss 40 located at the distal end of the horn 34, and it is fixed to the ring vibrator 21 by silver brazing or welding. FIG. 12(b) is a view of the horn 34 having the ring vibrator 21 as seen from above. The ring vibrator 21 is fastened so that its center axis may orthogonally intersect the center axis of the horn 34.

FIGS. 13(a)-13(c) are views showing another embodiment on the horn shape, in which FIG. 13(a) is a front view of the horn 34, FIG. 13(b) is a side view thereof and FIG. 13(c) is a rear view thereof. In order to facilitate machining, the horn 34 is put into the shape of a circular cylinder. FIG. 14 shows a sectional view of the circular cylindrical horn 34 illustrated in FIGS. 13(a)-13(c).

FIGS. 15 and 16 are views showing another embodiment of and near the suction pipe furnished with two injection valves. The two injection valves 13a and 13b are mounted on the fuel passage plate 26, and the fore ends of the respective injection valves 13a and 13b inject fuel from nozzle portions 28a and 28b to the inner walls of the ring vibrators 21a and 21b. With this structure, the fuel injection is executed in time with the suction stroke of the engine. FIG. 16 is a sectional view corresponding to FIG. 15. The vibrators 12a and 12b are received in the spacer 25, and the nozzles 28 suspend from the fuel passage plate 26 on the upper stream side to the centers of the ring vibrators 21a and 21b. FIG. 17 is a more enlarged view corresponding to FIG. 16. The fuel injected from the injection valve 13 passes through a passage 57 and reaches the nozzle portion 28, and it is injected to the corresponding ring vibrator 21 from an extreme end 58 which is formed smaller in bore than the fuel passage 57. Thus, the quantities of fuel injection are equalized.

FIGS. 18 and 19 are views showing an embodiment in the case where the two ring vibrators 21a and 21b are excited by a single ring-shaped ultrasonic vibrator 31. A horn 50 in the shape of a circular cylinder is arranged so as to penetrate the side walls of the ring-shaped vibrator 31, and it is fastened to the ring-shaped ultrasonic vibrator 31 through stiffening plates 51a and 51b by nuts 52a and 52b. At both the ends of the horn 50, the ring vibrators 21a and 21b are fixed by welding. Since, in this case, the ring-shaped ultrasonic vibrator 31 vibrates in the radial direction thereof, the vibrations are propagated to the circular cylindrical horn 50 through the stiffening plates 51a and 51b and are transmitted to the ring vibrators 21a and 21b as longitudinal vibrations. As compared with the Langevin type vibrator mentioned before, such arrangement has the advantage that the plane of vibrations can be set as the whole surface in the circumferential direction.