JP2851170B2 - Fuel supply device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an internal combustion engine, and more particularly to a fuel supply system of the type called an air blast valve which mixes fuel and air in an injection valve before injecting the mixture.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 2-140457 discloses an example of a so-called air blast valve. A fuel supply device of a type generally called an air blast valve injects a required amount of liquid fuel from a fuel metering valve into a high-pressure gas body such as compressed air supplied to a mixing space inside the valve body. Thereafter, the air injection valve provided at the outlet of the mixing space is opened at a predetermined timing, and the mixture of fuel and gas is injected at a high pressure into the combustion chamber or the intake passage of the internal combustion engine to atomize the fuel. It is intended.

[0003]

According to the conventional air blast valve, the atomization of the fuel proceeds more than in the case of a normal fuel injection valve which pressurizes and injects only the fuel, and the average particle diameter becomes 20%.
Although fine particles of fuel of about μm can be obtained, a combustion state that satisfies the current HC emission regulation value of an internal combustion engine for a vehicle can be obtained by this. Since atomization is by no means sufficient, it is considered necessary to further atomize the fuel by some means.

As one means for reducing the particle size of fuel, increasing the temperature of the injected fuel by heating the fuel injector is disclosed, for example, in JP-B-49-4524.
As described in Japanese Patent Application Laid-Open No. 9-109, there has been an attempt to heat the fuel in a normal fuel injection valve for an internal combustion engine. The fuel vapor causes a measurement problem that the actual fuel injection amount is reduced or fluctuates, and when the fuel injection valve is externally heated, heat is dissipated into the airflow in the intake passage, Since a sufficient heating time cannot be obtained, it is necessary to provide a powerful heating device, and as a result,
There is a problem that the power consumption for heating the fuel is increased, and in fact, a means for efficiently obtaining the atomized fuel by the fuel injection valve has not yet been established.

[0005]

According to the present invention, as a means for solving the above-mentioned problems, there is provided a nozzle which is mounted at a predetermined position of an engine, and a mixture of fuel and air is intermittently injected into the engine from an opening thereof. An air injection valve that receives the supply of compressed air, a compressed air passage that leads to an upstream side of the opening of the nozzle of the air injection valve, and a supply passage that receives the supply of pressurized fuel and is provided in the compressed air passage. A fuel metering valve that intermittently injects fuel into the compressed air passage by injecting an amount of fuel intermittently into the compressed air passage from the opened opening into the compressed air passage, and the fuel in the compressed air passage. A heating device provided to heat fuel in the compressed air passage downstream of the opening of the metering valve and upstream of the opening of the air injection valve. Providing a fuel supply device.

[0006]

When the amount of fuel corresponding to the operating state of the engine is intermittently injected from the fuel metering valve into the compressed air passage, the injected fuel is opened downstream of the fuel metering valve at the opening of the air injection valve. It temporarily stays in the compressed air passage upstream of it. Since the compressed air passage is heated by the heating device, the fuel injected into the compressed air passage is efficiently heated by the heat, and is mostly vaporized and mixed with the compressed air. Then, when the air injection valve is opened, the mixture of fuel and air is ejected to the outside from the opening of the air injection valve, and the fuel is further atomized by the decompression and is uniformly mixed with the air. Be supplied to the organization.

[0007]

FIG. 1 is a schematic sectional view showing the structure of a main part of an air blast valve 10 according to an embodiment of the fuel supply apparatus of the present invention. And the air injection valve 16. When the solenoids 18 and 20 are energized, the respective valves 14 and 16 cause the tips of the respective needles 22 and 24 to open the openings 26 and 28. The valve is to be opened.
The two solenoids 18 and 20 are independent of each other, and the fuel metering valve 14 and the air injection valve 16 can each open at different times. Fuel pressurized to a predetermined pressure by an external fuel pump (not shown) is supplied to the fuel supply passage 30 on the upstream side of the fuel metering valve 14, and an amount of fuel corresponding to the opening time of the fuel metering valve 14 is supplied. Is injected into a compressed air passage 32 formed as a space in the main body 12.

The compressed air passage 32 receives the supply of compressed air from an external compressor (not shown) and guides the compressed air to the opening 28 through a tubular space around the needle 24 passing through the center of the nozzle 17 of the air injection valve 16. These spaces are configured to be filled with compressed air. The fuel injected from the opening 26 of the fuel metering valve 14 is mixed into the compressed air in the compressed air passage 32 as described above. The fuel injected into the compressed air passage 32 is mixed with air in the form of an emulsion, and a part of the fuel is vaporized, but most of the fuel flows through the compressed air passage 32 and flows into the tubular space around the needle 24 in the nozzle 17. Accumulate. Therefore, this tubular space is referred to as a fuel holding chamber 34. The nozzle 17 of the air injection valve 16 is connected to the body of the air blast valve 10 by a bolt or the like (not shown) so that the opening 28 is located on the combustion chamber of the internal combustion engine (not shown) or on the upstream side of the intake valve in the intake passage. Attached to the body. Reference numeral 13 denotes a mounting portion formed on a part of the main body 12 for that purpose.

The fuel metering valve 14 and the air injection valve 16 of the illustrated embodiment have a structure that opens when the needles 22 and 24 are moved outward by the solenoids 18 and 20, respectively. The present invention is not characterized by the specific structure of the fuel metering valve 14 and the air injection valve 16.

According to the features of the present invention, the compressed air passage 3
A heating device 36 is provided on the outer periphery of the fuel holding chamber 34 which is a part of
Is mounted, so that fuel staying in the fuel holding chamber 34 can be heated. A detailed structural example of the heating device 36 is shown in a sectional view in FIG. In the figure, 3
Reference numeral 8 denotes a glass tube fitted to the nozzle 17 and made of quartz glass having excellent heat resistance, and a heating wire 40 is wound around the outer periphery thereof. The outside of the heating wire 40 is surrounded by a ceramic body 42 so as to bury it, so that the heating wire 40 is thermally and electrically insulated from the outside. The glass tube 38 includes the heating wire 40 and the nozzle 17.
Although the space between them is electrically insulated, the heat generated by the heating wire 40 can be efficiently transmitted to the nozzle 17 because the thickness is small. Reference numeral 44 denotes a lead wire connected to the heating wire 40.

Next, the operation of the embodiment will be described. In each cycle of the engine, fuel measured according to the operating state of the engine is injected from the fuel supply passage 30 into the compressed air passage 32 by the fuel metering valve 14. The fuel metering valve 14 is the solenoid 1
8, the valve is opened and the opening 26 is opened. During operation, compressed air pressurized from a compressor (not shown) is always supplied to the compressed air passage 32, so that the fuel injected from the opening 26 flows while mixing with the air in the compressed air passage 32. Fuel holding chamber 3 upstream of the opening 28
4 and stay in the fuel holding chamber 34 until the air injection valve 16 is opened. Heating wire 4 of heating device 36
When 0 is energized, the fuel holding chamber 34 is locally heated by its heat generation, so that most of the fuel staying there receives heat, evaporates, and mixes well with air. The heating of the fuel according to this embodiment is performed so that the fuel temporarily stays in the fuel holding chamber 34 and the heating apparatus 36 can heat the fuel holding chamber 34 intensively. Is surrounded and insulated by the ceramic body 42, so that it can be performed efficiently and promptly with low power.

When the injection timing comes, the solenoid 20 is urged and pushes down the needle 24 to open the opening 28, and the mixture of fuel and air in the fuel holding chamber 34 is injected into the intake passage or the combustion chamber of the engine. . The fuel is injected from the fuel metering valve 14 into the compressed air passage 32 and mixed with the compressed air in a state where the fuel is pressurized to a pressure higher than the pressure of the compressed air in advance. Although some of the fuel is atomized and partially vaporized due to collision with the high temperature portion of the wall surface of the fuel cell 32, the fuel remaining in the form of droplets is also heated by the heating device 36 while remaining in the fuel holding chamber 34. By being heated by, most of the gas evaporates and mixes with air. Therefore, when a mixture of fuel and air is injected from the opening 28 of the air injection valve 16, the fuel is converted into fine particles of all molecules due to the reduced pressure, the liquid fuel is completely lost, and the fine fuel particles are generated during intake. By uniformly diffusing, an intake air-fuel mixture that easily burns completely is obtained.

The fuel retention period in the fuel holding chamber 34 is controlled by the fuel metering valve 14 with respect to the opening timing of the air injection valve 16.
Can be arbitrarily set within a predetermined range by changing the valve opening timing of the fuel cell. However, in order to enhance the heating effect, the fuel stays in the fuel holding chamber 34 for as long as possible. It is clear that it is better to make the fuel metering valve 14 close immediately after the air injection valve 16 is closed, as shown in FIG.
The timing should be such that the valve opens. Further, as shown in FIG. 3, when the present invention is carried out, it is advantageous to open the air injection valve 16 during the intake stroke of the engine. This is because injection strokes with insufficient fuel atomization as in the prior art could not perform the intake stroke injection due to the increase in the amount of HC emission, whereas such injection valves can be obtained by implementing the present invention. In the case of an air-fuel mixture in which the fuel has been atomized, the HC discharge amount does not increase even if the intake stroke injection is performed as shown in FIG. 4, and consequently the HC discharge amount tends to decrease. That's why. In this case, the reduction in HC emission and the improvement in responsiveness can be simultaneously obtained by the intake stroke injection.

FIG. 5 shows a case where the number of revolutions of the engine is 3000 rpm as compared with the case of FIG. 4 where the number of revolutions of the engine is 1200 rpm. Therefore, there is a tendency that the effect of reducing HC is reduced. Therefore, the power consumption can be reduced by stopping the power supply to the heating device 36 at a rotation speed of about 3000 rpm.

FIG. 6 shows a comparison of the amount of HC emission due to ON-OFF of the heating device 36 when the cooling water temperature is maintained at 80 ° C., which is higher than 30 ° C. in FIGS. 4 and 5. As a result, the effect of reducing HC by heating is reduced as the cooling water temperature rises. Therefore, when the water temperature reaches about 60 ° C., the power supply to the heating device 36 is stopped to reduce the power consumption. It is a good idea to do this.

When the power supply is stopped in any of the above states, the opening timing of the fuel metering valve 14 and the air injection valve 16 is changed, and as shown in FIG. It is preferable to shorten the period to improve the control response of the engine.

Incidentally, the amount of current supplied to the heating device 36 should be changed in accordance with the load so as to prevent insufficient heating or excessive heating. Generally, the distillation curve of fuel (gasoline) is as shown in FIG. 8, so that when the temperature reaches 200 ° C., the fuel is completely vaporized. Accordingly, the fuel heating is set at a target value of 200 ° C., and the engine load (fuel flow rate) is set so that excessive heating or insufficient heating can be avoided.
, The amount of electricity supplied to the heating device 36 is controlled. FIG. 9 shows an example of this control.

[0018]

According to the present invention, the fuel which is intermittently metered and injected in the compressed air passage is temporarily stored and is heated by the heating device, so that the injection amount does not fluctuate. In addition, since the amount of heat dissipated to the outside is small, and heating is performed using the fuel residence period, the heating time can be made relatively long, and the fuel can be efficiently vaporized.

Since most of the vaporized fuel is injected together with the compressed air, atomization of the fuel proceeds, and a very high-quality air-fuel mixture is obtained, which is sucked into the engine and completely combusted. The amount is reduced, the combustion efficiency of the engine is improved, and the power performance such as output is also increased. Therefore, the present invention is beneficial to the engine in various senses as well as measures against exhaust pollution, but the special parts to be added are only a simple heating device and the amount of electric power required is small. It is advantageous in terms of both manufacturing costs and operating costs.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing a structure of an air blast valve according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view showing a structural example of a heating device as a main part of the present invention.

FIG. 3 is a time chart showing a control example of the opening timing of an air injection valve and a fuel metering valve.

FIG. 4 is a diagram showing the amount of HC emission of the embodiment in comparison with the prior art.

FIG. 5 is a diagram showing the amount of HC emission of the embodiment device in a state different from the case of FIG. 4;

FIG. 6 is a diagram showing the amount of HC emission of the embodiment apparatus in a state different from the cases of FIGS. 4 and 5;

FIG. 7 is a time chart showing another control example of the opening timing of the air injection valve and the fuel metering valve different from FIG.

FIG. 8 is a diagram showing characteristics during distillation of gasoline.

FIG. 9 is a diagram showing an example of control of energization of a heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Air blast valve 14 ... Fuel metering valve 16 ... Air injection valve 18, 20 ... Solenoid 22, 24 ... Needle 32 ... Compressed air passage 34 ... Fuel holding chamber 36 ... Heating device 40 ... Electric heating wire

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromasa Takeda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-2-140457 (JP, A) JP-A-2- 252968 (JP, A) JP-A-4-12158 (JP, A) JP-A-4-234567 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 67/02 F02M 67 / 12 F02M 69/00 F02M 31/12

Claims (1)

(57) [Claims] An air injection valve having a nozzle attached to a predetermined position of an engine and intermittently injecting a mixture of fuel and air into the engine from an opening thereof; A compressed air passage leading to an upstream side of the opening of the nozzle, and an amount of fuel corresponding to an operation state into the compressed air passage from an opening provided in the compressed air passage receiving a supply of pressurized fuel. A fuel metering valve that intermittently injects fuel into the air in the compressed air passage by injecting fuel into the compressed air passage, and a position downstream of the opening of the fuel metering valve in the compressed air passage below the opening of the air injection valve. A heating device provided for heating fuel in the upstream compressed air passage.