JPS6111451A - Fuel injection device - Google Patents

Abstract

PURPOSE:To make it possible to minutely control the amount of fuel even at injection of the minimum amount of fuel, by injecting fuel in a liquid chamber having an injection port in the form of fuel drops into a suction passage by driving an electrostrictive vibrator receiving an electric signal. CONSTITUTION:A fuel pump 13 and an air pump 16 are driven to increase a fuel pressure in a liquid chamber 6 to P2 and increase an air pressure in a pressure air chamber 10 to P1. At this time, an injection port 7 continues to be sealed by a liquid membrane G1 of fuel. When a starter is driven, suction pressure P0 in a suction passage 4 becomes negative. Simultaneously, an optimal pulse signal for a starting condition is applied to each piezoelectric device 2, and fuel drops g are injected from each injection port 7 through an opening 9 into the suction passage 4 every time the device 2 receives the pulse signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device for injecting fuel into an intake passage of an internal combustion engine.

Internal combustion engines for vehicles need to change their operating conditions over a wide range from idle to full load operation, and the amount of intake air and fuel supply are adjusted over a wide range. As one of the methods for adjusting the amount of fuel supplied, a fuel supply system is known in which a fuel injection device is attached to the intake passage of a gasoline engine, and thereby fuel is injected into the intake passage. This fuel supply system pressurizes fuel using a fuel pump, and injects this pressurized fuel at the appropriate time by opening and closing a solenoid valve in the fuel injection device. It is adjusted according to engine speed, etc.

As described above, the fuel injection device used in the conventional fuel supply system uses a solenoid valve as an on-off valve.

The minimum injection amount and maximum injection amount are determined by the response characteristics of the solenoid. In this case, the maximum injection amount of most fuel injection devices is regulated to be 40 to 80 times the minimum injection amount, and the dynamic range tends to be narrow. On the other hand, the dynamic range required by the engine often exceeds 100. For this reason, conventionally, when matching the engine and fuel injection device, the minimum injection amount of the fuel injection device was increased to enable full load operation on the engine side.

As a result, the maximum injection amount of the fuel injection device is adjusted to the injection amount corresponding to a dynamic range of 100 required by the engine. For this reason, when the conventional fuel injection device injects the minimum injection amount.

There is a problem in that minute fuel amount control cannot be performed. An object of the present invention is to provide a fuel injection device that can eliminate the above-mentioned problems.

In order to achieve the above-mentioned object, the present invention is characterized in that fuel in a liquid chamber equipped with an injection port is injected as fuel droplets into an intake path of an internal combustion engine by driving an electrostrictive vibrator that receives an electric signal. This is what I did.

In such a fuel injection device, an electrostrictive oscillator is driven every time an electric signal is received, and the fuel is turned into fuel droplets and injected. I can do it big.

FIG. 1 shows a fuel injection device as an embodiment of the present invention. This fuel injection device is attached to an intake pipe 1 of a gasoline engine (not shown), and is formed by arranging a plurality of main bodies 3 each having a piezo element 2 therein as an electrostrictive vibrator. In addition.

The number of main bodies 3 used is sufficient to ensure the maximum injection amount to the engine, and they may be arranged in a plane as shown in Figs. 4 and 5, or in the intake pipe as shown in Fig. 6. 1
The main bodies 3 may be arranged in a plurality of rows along the air intake passages 4 inside. In FIG. 1, one of the main bodies 3 will be mainly explained.

The main body 3 has a body 5 and a liquid chamber 6 in the body.

an injection lower formed on the opposite side of the liquid chamber 6 to the intake passage 4;
It covers the fuel supply chamber 8 communicating with the liquid chamber 6 near the injection lower and the four sides on the outlet side of the injection lower.

A pressurized air chamber 1 having an opening 9 formed at a position facing the injection lower
0. The entire upper wall of the liquid chamber 6 is formed by the piezo element 2, a small diameter injection lower is provided at the lower end, and the entire liquid chamber 6 has a substantially inverted conical shape. The piezo element 2 has electrodes (not shown) formed on the upper and lower surfaces.

A pulse signal for driving the computer 11 is applied to this. Here, as shown in FIG. 2 Tbl, when the pulse signal of the voltage V rises from OFF to ON, the piezo element 2 is distorted as shown by the two-dot chain line in FIG. 2 (al).

At this time, the piezo element 2 converts electrical energy into mechanical energy. This mechanical energy is converted into acoustic energy and transmitted into the fuel G in the liquid chamber 6.

As a result, the fuel becomes particles and is injected as fuel droplets from the injection lower part (see Fig. 3 (al)).

The injection lower has a relatively small diameter and is sealed by a liquid film G1 of fuel when the piezo element 2 is not driven.

This liquid film G1 is formed due to the surface tension of the fuel,
This is formed by keeping the pressure difference between the inside and outside of the injection lower within a certain value, and if it exceeds this value, it will be destroyed. The fuel supply chamber 8 is formed in a direction perpendicular to the liquid chamber 6 which is long below the road, and supplies fuel to the liquid chamber 6 when the piezo element 2 returns to the non-driving state as shown in FIG. I can do it.

A fuel pump 13 and a fuel tank 14 are connected to the fuel supply chamber 8 via a fuel pipe 12. On the other hand, the pressurized air chamber 10 is formed closest to the intake path 4 in the body 5 and is supplied with pressurized air from an air pump 16 through an air pipe 15. The pressurized air that has flowed into the pressurized air chamber 10 flows out from the opening 9 into the intake path 4 where the intake pressure PO, which is a negative pressure, applies an air pressure P1 to the injection lower. Note that the air pressure P1 only needs to be able to form a liquid film G1'f on the injection lower, and is set to a value equal to or close to the fuel pressure P2. Here PI > P2
is set to . In addition, as shown in FIG. 8, an on-off valve 18 may be installed to close the injection lower to the pressurized air chamber 10 side. This on-off valve 18 is a normally closed solenoid valve, and when the ignition switch 19 is turned on, the solenoid 20
is driven to hold the on-off valve 18 in the closed and open position (the position shown by the solid line in FIG. 8). The on-off valve 18 is always pressed against the injection lower side wall by a spring 21 mounted in the pressurized air chamber lo. In this case, the liquid chamber 6 can be closed when the key is turned off, thereby preventing gas from entering the liquid chamber and forming a cavity. The computer 11 calculates the intake air amount based on the pulse signal input from the air flow sensor 17, and detects each operating state based on the input signal from a sensor (not shown).
The amount of fuel supplied that provides the optimum air-fuel ratio is calculated accordingly. Then, in order to obtain the number of injections corresponding to this fuel supply amount, pulses of a predetermined voltage V are outputted to the piezo element 2 a predetermined number of times per unit time.

The fuel injection system shown in FIG. 1 is activated when an engine key (not shown) is turned on. First, the fuel pump 13 and the air pump 16 are driven to increase the fuel pressure in the liquid chamber 6 to P2 and the air pressure in the pressurized air chamber 10 to Pl, and the injection lower continues to be sealed by the liquid film G1 made of fuel. continue,
When the engine key drives the starter, the intake pressure PO in the intake passage 4 becomes negative pressure. computer 1 at the same time
1, the optimum pulse signal for the starting state VC is applied to each piezo element 2.
is applied, and fuel droplets t are injected into the intake passage 4 from each injection lower through the opening 9 every time a pulse signal is received. In this case, fuel droplets 9 are injected from each of the plurality of main bodies 3,
The air-fuel mixture formed in the intake passage 4 is combusted in a combustion chamber (not shown), and the engine is started. Thereafter, the computer 11 simultaneously outputs an optimal number of pulse signals to the plurality of main bodies 3 according to the operating state.

This causes the engine to generate power and the vehicle to move.

In the above, the main body 3 includes one piezo element 2,
Instead of this, one piezo element 2 is provided in one main body 37, and liquid chambers 6 are formed on both sides of the piezo element 2, as shown in FIG. Injection lowers may be formed at the left and right ends of the chamber, each injection lower is covered with a pressurized air chamber 1o, and an opening 9 may be formed in each pressurized air chamber 1o at a position facing the injection lower.

In the case of B, a total of two injections can be performed, one from both injection lowers each time one pulse is applied to one main body 3' (piezo element 2), and the number of one main body can be halved, securing installation space. becomes easier. Furthermore, if the main body 3 described above is made as a device similar to an inkjet head used in a recording device, a so-called on-demand head, the amount of ejection per drop is small, but the installation space of the main body 3 is small. As long as the inkjet head can be sufficiently secured, the present device can be created by using several dozen devices similar to this inkjet head. Furthermore, by using the main body 3 which can sufficiently increase the amount of droplets, a fuel injection device can be created with several main bodies.

Furthermore, although each of the above-mentioned main bodies 3 was equipped with the pressurized air chamber 1o, in the case where the injection lower is disposed opposite to the discharge side of the turbocharger where the intake path 4 becomes positive pressure, the pressurized air chamber 1o is 10 may be excluded.

In this way, the fuel injection device according to the present invention has the episodic element 2
Since it is driven by a pulse signal, the episodic element 2 can be driven approximately 10,000 to 20,000 times per second, and its dynamic range itself can be very large. Therefore, it is possible to control the amount of injection in an extremely small amount, and in this respect, fuel efficiency can be improved compared to the conventional method. Moreover, since the dynamic range is large, it is possible to accurately control the injection amount from the minimum to the maximum injection amount.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a fuel injection device as an embodiment of the present invention, FIGS. 2 and 3 are sectional views of essential parts explaining different operations of the same fuel injection device, and FIG. 4 is a schematic sectional view of a fuel injection device as an embodiment of the present invention. 5 is a schematic sectional view of the device shown in FIG. 4, FIG. 6 is a schematic sectional view showing another arrangement of the two main bodies, and FIGS. FIG. 8 shows sectional views of essential parts of fuel injection devices as other different embodiments of the present invention. 2...Piezo element, 4...Intake path, 6...
Liquid chamber, 7... Injection port, 9... Opening, 1o...
- Pressurized air chamber, G1...liquid film, G...fuel.

Claims (1)

[Scope of Claims] A liquid chamber that is disposed opposite to an intake passage of an internal combustion engine and receives fuel supply, an electrostrictive vibrator that transmits vibrations to the fuel in the liquid chamber by receiving an electric signal, and the liquid chamber. and an injection port that is in communication with the injection port and can be sealed by a liquid film of fuel, and injects fuel droplets into an intake passage through the injection port by driving the electrostrictive vibrator.