JPH03281981A - Fuel supply unit for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the response of fuel supply in the same cycle of an engine by providing a fuel injection valve to supply fuel to an atomizing part of an ultrasonic vibrating member provided in an intake pipe, and providing an assisting air flow generating means to increase the flow velocity around the atomizing part. CONSTITUTION:An ultrasonic atomizer 11 consisting of a fuel injection valve 9 and an ultrasonic vibrating member 10 is attached to an intake pipe 4 at a position in the downflow side of a throttle valve 8. On one end of the ultrasonic vibrating member 10, an atomizing part 12 is provided, and on the other end of which an electroacaustic transducer element 13 is provided. And when an engine 1 is in operation, during the fuel injection period, ultrasonic vibrations of a high amplitude are applied to the ultrasonic vibrating means 10, and during the stopping period of fuel supply, ultrasonic vibrations of a low amplitude are applied to the means 10 so that, under such low amplitude vibrations, even when fuel drops are adhered to the atomizing part 12 they cannot produce fine particles. And during the fuel supply, the velocity of the air flow around the atomizing part 12 is increased to generate an assisting air flow to promote the formation of a liquid film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to spark ignition engines that use low-volatile fuels such as gasoline and kerosene, low cetane number fuels such as cracked light oil, or alcohol fuels. In particular, the present invention relates to a fuel supply system for an internal combustion engine that is applied to a system that uses an electronically controlled fuel injection valve and an ultrasonic vibration member.

[Prior Art] Conventionally, a method is known in which an ultrasonic atomizer is disposed in the intake pipe of an internal combustion engine to atomize fuel and mix it with intake air to supply an air-fuel mixture to the engine. For example, JP-A-53-1
In Publication No. 40iEt, a method is known in which a fuel supply device and an ultrasonic vibrator are arranged in the intake pipe passage to improve the mixing of the intake air and the ultra-atomized fuel obtained by the ultrasonic vibrator. There is.

On the other hand, for example, in a gasoline engine that supplies fuel to the intake pipe, the fuel flow velocity in the intake pipe is slower than the air flow velocity, so the air-fuel mixture in the cylinder becomes lean (lean spike) during acceleration, causing sluggish acceleration. . For this reason, the vaporization type is provided with a starting increase mechanism, and the system using an electronically controlled fuel injection valve is used to increase the amount of fuel at an accelerated rate.

[Problems to be Solved by the Invention] However, in the conventional method described above, even if the ultrasonic atomizer intermittently supplies fuel at a cycle of several tens of eighty-two or more, the resulting spray has a low injection rate. This results in problems such as fuel adhering to the pipe wall and not being able to supply fuel within the required period. Particularly in high-output engines, there is a problem in that when the engine is started at a low outside temperature and when the engine is picked up when rapidly accelerating from a low speed, the air-fuel mixture conveying speed decreases, making it impossible to obtain the desired output. Furthermore, when the engine is accelerating, a portion of the fuel is supplied with a one-cycle delay, resulting in a problem of poor acceleration response.

On the other hand, there are known ultrasonic atomizers that vibrate ultrasonic waves intermittently to obtain intermittent atomization, but it takes a long time after the power is turned on until the ultrasonic vibrator horn reaches a steady vibration state. Therefore, in a cycle such as that of an internal combustion engine, there is a problem that the ultrasonic vibration cannot follow the fuel supply cycle.

The present invention solves the above problems, and by achieving intermittent atomization using an ultrasonic atomization device, it aims to reduce the amount of fuel adhering to the inner wall surface of the intake pipe, and also to reduce the amount of fuel that adheres to the inner wall surface of the intake pipe. An object of the present invention is to provide a fuel supply device for an internal combustion engine that can improve the responsiveness of the engine.

[Means for Solving the Problems] For this purpose, the fuel supply device for an internal combustion engine of the present invention includes an ultrasonic vibration member 10 disposed in the intake pipe 4 of the engine 1;
A fuel injection valve 9 that supplies fuel to the atomizing section 12 of the vibrating member
and an amplitude setting that applies high-amplitude ultrasonic vibration to the vibrating member 10 for a predetermined time in synchronization with the drive signal of the fuel injection valve 9, and then applies low-amplitude ultrasonic vibration to the vibrating member 10. and means for forming an air assist flow 17 that increases the flow velocity around the atomization section 12.

Note that the numbers added to the above configurations are for comparison with the drawings to facilitate understanding, and the configurations of the present invention are not limited thereby.

[Operation] In the present invention, high-amplitude ultrasonic vibration is applied to the ultrasonic vibration member while fuel injection is being performed, and low-amplitude ultrasonic vibration is applied while fuel is not being supplied. Vibration is applied, and in a low amplitude vibration state, ultrasonic vibration is applied, but a state is created in which even if the liquid adheres to the atomization part, it does not become atomized. Furthermore, during fuel supply, the speed of the air flow around the atomization part is increased to form an air-assist flow, and the liquid film is narrowed by the air pressure and the liquid is quickly sent to the atomization surface to form a liquid film. This will promote

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a fuel supply system for an internal combustion engine according to the present invention.

The spark ignition engine 1 has a cylinder 2, a piston 3, an intake pipe 4, an exhaust pipe 5, an intake valve 6, and an exhaust valve 7.
A throttle valve 8 is disposed on the side, and an ultrasonic atomizer 11 comprising a fuel injection valve 9 and an ultrasonic vibrating member 10 is attached downstream thereof. Ultrasonic vibration member 10
An atomizing section 12 is formed at one end, and an electric/atomizer is formed at the other end.
An acoustic transducer element 13 is provided. Furthermore, an air pump 14 is connected midway through the intake pipe 4, and an air filter 15 is provided at the inlet.

As shown in FIG. 2, the ultrasonic vibrating member 10 has a bat-like shape including an enlarged diameter portion 12a1 and reduced diameter portions 12b and 12c, and forms an atomization portion 12 on the distal end side. Note that the most effective shape of the atomizing section 12 is a bat-like shape.
The present invention is not limited to this, but an enlarged diameter type in which the outer diameter increases toward the tip, a stepped type, and other well-known shapes may be adopted.

Next, the internal combustion engine fuel supply method of the present invention will be explained with reference to FIGS. 3 and 4. Figure 3 is a configuration diagram of the control system.
FIG. 4 is a diagram showing a timing chart of control.

In FIG. 3, reference numeral 21 denotes an electronic control device that calculates and processes input signals such as engine speed, throttle opening, and chilled water temperature (not shown), and outputs the injector TTL signal as shown in FIG. 4(a). Then, a high level signal for a predetermined time T1m5 is output to the fuel injection valve 9, and the ultrasonic vibration member 1
Fuel is intermittently supplied to the atomizing section 12 of the engine. In the fuel injection valve 9, as shown in (b), since the valve opening and closing operations are delayed, fuel is injected during T2 ms-T3 as.

At the same time, the injector TTL signal is
T4 is sent to T4 in synchronization with this, as shown in (C).
was time, create a high-level ultrasonic amplitude signal.

This ultrasonic amplitude signal is sent to the voltage control circuit 23, where the voltage is set so that when the ultrasonic amplitude signal is at a high level, the ultrasonic vibration becomes high in amplitude, and when the ultrasonic amplitude signal is at a low level, the ultrasonic vibration is generated. A voltage with a low amplitude is output to the high frequency oscillation circuit 24, and the electric/acoustic transducer 13
This is what drives the.

Finally, as shown in (d), in the ultrasonic vibration member 10, ultrasonic vibration is applied at high amplitude while fuel is being supplied, and while fuel is not being supplied, ultrasonic vibration is applied at high amplitude. applies ultrasonic vibrations with low amplitude. In this low-amplitude vibration state, ultrasonic vibrations are applied, but even if the liquid adheres to the atomizer, it does not become atomized. Most of the fuel supplied is atomized at high amplitudes. Furthermore, since the power is not turned off, the rise time of the next high-amplitude ultrasonic vibration can be shortened. Therefore, while the ultrasonic vibrations are continuously applied, the amplitude of the ultrasonic vibrations is changed to atomize the intermittently supplied fuel, and the fuel can be sprayed intermittently.

According to the experimental results, the fuel injection valve applied pulse width TI
When the maximum amplitude is 511 seconds and the high amplitude is 24 to 26 μm10 and the amplitude is 4 to 5 μm, it is necessary to maintain the high amplitude for only 5 ms, regardless of the pulse width TI applied to the fuel injector, and if it is longer than this, the spray It was confirmed that cutting becomes worse and atomization becomes worse if the length is short.

Furthermore, in the present invention, the air pump 14 is driven during the fuel supply to increase the speed of the air flow around the atomization section 12 and form the air assist flow 17.

To explain this with reference to FIG. 5, if there is no air assist flow 17, the liquid film supplied from the fuel injection valve exists as shown in A, and the atomization surface C due to the action of gravity and ultrasonic vibration. However, when the air assist flow 17 is applied, the liquid film is constricted by the air pressure as shown in B, and the liquid is quickly sent to the atomization surface C, promoting the formation of the liquid film. .

8 and 7 show experimental results related to the present invention, where the vertical axis represents the injection ratio of atomized fuel, and the horizontal axis represents the elapsed time after the valve opening pulse was applied to the fuel injection valve 9. It shows. In addition, the intake speed when there is no air assist flow is 5 m/5ee1, the intake speed when an air assist flow is formed is 8 m/see, the fuel supply cycle is 1OH2, and the opening time of the fuel injection valve is 6 m/see. In the figure, 2 ll51 Figure 7 is 5g+s.

In the figure, USO is a type that supplies fuel to the atomizing section 12 through an annular passage, USD is a type that directly supplies fuel to the atomizing section 12, and USV is a type that directly supplies fuel and the above-mentioned variable This is a type that controls the amplitude.
USD-A and USV-A also have air assist flow 1
This is the type that works with 7.

FIG. 8 summarizes the above experimental results.

In the figure, the numbers in parentheses indicate the time reduction relative to USD. When looking at the spray end time in terms of 80% and 90% ratio, by adopting USV-A (direct injection, variable amplitude and air assist), the spray end time is the shortest.
It has been found that the problems of injection delay and delay are improved.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made.

For example, in the above embodiment, fuel is supplied intermittently by the fuel injection valve, but even if a small amount of fuel is supplied continuously, intermittent atomization is possible by varying the amplitude. .

[Effects of the Invention] As described above, according to the present invention, by employing direct injection, variable amplitude, and air assist method using an ultrasonic atomization device, the problems of injection delay and intermittent injection are improved and intermittent spraying is achieved. By achieving this, it is possible to reduce the amount of fuel adhering to the inner wall surface of the intake pipe, and to improve the responsiveness of fuel supply within the same cycle. Furthermore, the driving power can be reduced by the amount by which ultrasonic vibrations are applied with low amplitude.

Furthermore, compared to the case of continuous vibration with a constant amplitude that can be atomized, in the case of the present invention, the amplitude when the fuel collides with the vibrator horn is small, so there is less fuel scattering due to collision, which is good. Atomization can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the fuel supply system for an internal combustion engine according to the present invention, FIG. 2 is an enlarged view of the atomization section in FIG. 1,
Figure 3 is a configuration diagram of the control system, Figure 4 is a diagram showing a timing chart of control, Figure 5 is a diagram for explaining the action of air assist flow, Figures 6, 7, and 8 are FIG. 3 is a diagram for explaining experimental results related to the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 4... Intake pipe, 9... Fuel injection valve, 10... Ultrasonic vibration member, 12... Atomization part, 1
7... Air assist flow, 22... Amplitude setting circuit. Applicant: Tonen Corporation

Claims (1)

[Claims] (1) An ultrasonic vibrating member disposed in the intake pipe of the engine, a fuel injection valve that supplies fuel to the atomizing section of the vibrating member, and a amplitude setting means for applying high-amplitude ultrasonic vibrations to a vibrating member and thereafter applying low-amplitude ultrasonic vibrations to the vibrating member; and means for forming an air-assisted flow that increases the flow velocity around the atomizing section. A fuel supply device for an internal combustion engine, comprising: