JPS593190Y2 - Internal combustion engine fuel injection system - Google Patents

Description

[Detailed description of the invention] The invention improves the fuel injection characteristics of a fuel-injected internal combustion engine,
The present invention also relates to a fuel injection device that improves fuel supply accuracy.

In conventional fuel injection systems for internal combustion engines, particularly in systems that use a computer or the like to control the amount of fuel injected, the pressure of the fuel supplied to the fuel injection valve installed in the intake pipe is controlled by the fuel pressure regulator. The pipe pressure signal is introduced to control the fuel pressure to a constant differential pressure with respect to the suction negative pressure, while the opening/closing time of the injection valve is controlled according to the engine operating conditions. A method was adopted in which the amount of fuel was injected.

Therefore, in this method, the fuel injection amount is controlled proportionally to the valve opening time of the injection valve, and the valve opening pulse time is controlled to be longer when the engine is at high speed and under high load, and conversely to be shortened when the engine is at low speed and under low load. As a result, the ratio between the maximum and minimum valve opening times (dynamic range) must become large.

For this reason, for example, if you try to inject at the required flow rate during low-speed, low-load operation using an injection valve with an injection amount that satisfies the maximum flow rate, the injection valve time must be significantly shortened. The valve opening action, together with the responsiveness of the injection valve and the accuracy of the injection diameter, causes problems such as making stable operation, that is, accurate fuel measurement, difficult.

Conversely, in order to emphasize performance at low speeds and low loads, an injection valve with a small diameter must have a sufficiently long valve opening time at high speeds and high loads, but this time has an upper limit due to the relationship with engine rotation. Due to the regulations, it is not possible to secure the required flow rate during high loads, and there are restrictions on increasing output.

Furthermore, even if the dynamic characteristics of the fuel injection valve are improved to shorten the minimum response time, as the ratio of the dynamic range is large, the relative error in the opening/closing operation time of the injection valve will be large, which is unfavorable in terms of fuel supply characteristics. .

In view of the above, this invention supplies fuel to the injection valve based on control characteristics preset in the electronic control circuit device based on engine operating condition signals such as engine rotational speed, throttle valve opening, and intake air amount. By configuring the system to control the pressure, the supplied fuel pressure is controlled to be relatively increased as the engine shifts to high-speed, high-load operation, thereby allowing not only low-speed, low-load operation but also high-speed, high-load operation to occur. An object of the present invention is to provide a fuel injection device for an internal combustion engine that can realize a fuel injection valve that is controlled with high precision in all operating ranges.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

Figure 1 is an overall view of the device of the present invention, where 1 is the main body of the engine, 2
is an intake pipe, which has an air flow sensor 3, a throttle valve 4, and a fuel injection valve 5 in this order from upstream.

6 is an electronic control means including a microcomputer;
The engine operating conditions are detected based on the intake air amount signal from the air flow sensor 3, the throttle valve opening signal from the opening switch 4a of the throttle valve 4, the rotation speed signal from the engine circuit number detection device 7, etc., and are set in advance. Based on these characteristics, the opening time of the fuel injection valve 5 is controlled, and the set pressure of the fuel pressure adjustment mechanism 8 that supplies fuel to the injection valve is controlled.

9 is a fuel tank, 10 is a pump, and fuel is supplied through a passage 11.
The fuel is fed under pressure to the fuel pressure adjustment mechanism 8 through the passage 12, and is supplied to the injection valve 5 through the passage 12.

Further, surplus fuel from the fuel pressure adjustment mechanism 8 is returned to the tank 9 through a passage 13.

The fuel pressure adjustment mechanism 8 is composed of a diaphragm type fuel pressure adjustment section 14 and an electromagnetic negative pressure control section 15, as shown in FIG.

The fuel pressure adjustment unit 14 has a fuel pressure chamber 1B defined by a housing cover 16 and a diaphragm 17, and has a passage 11 from the pump 10 described above and a passage 12 to the injection valve 5.
are connected to each other in an open manner, and fuel is supplied to the injection valve 5 through this pressure chamber 18.

Further, this pressure chamber 18 is connected to the return passage 13 whose opening 13a is arranged opposite to a valve body 19 integral with the diaphragm 17, and when the valve body 19 moves downward, the opening 13a is narrowed or When the opening 13a is closed and moved upward, the opening 13a is opened.

Reference numeral 20 denotes a negative pressure chamber defined above the diaphragm 17 and between it and the housing 21. Negative pressure is introduced from the intake pipe 2 or from a negative pressure tank (not shown) through an open-connected passage 22. When the negative pressure in the pressure chamber 20 is large, the diaphragm 7 is moved upward against the action of the spring 23.

On the other hand, the negative pressure control unit 15 connects the housing 21 with an atmospheric chamber 25 in which a nozzle 24 communicating with the negative pressure chamber 20 is protruded inward.
and is defined by the diaphragm 26.

Atmospheric pressure is introduced into this atmospheric chamber 25 from the intake pipe 2 upstream of the throttle valve 5 through a passage 27.

A valve body 28 fixed to a diaphragm 26 is disposed opposite to the nozzle 24, and the valve body 28 is moved by vertical movement of the diaphragm 26.
opens and closes the nozzle 24.

A plunger 30 of an electromagnetic solenoid 29 is connected to the valve body 2B to form an electromagnetic valve, and the drive current applied to the solenoid 31 is turned on and off at a predetermined frequency, and when the on-off ratio (on duty) is increased, the plunger 3
0 moves upward, the diaphragm 26 is moved upward to open the nozzle 24, and atmospheric air is introduced into the negative pressure chamber 20, thereby making the negative pressure relatively small.

According to this configuration, during high-speed, high-load operation of the engine, the solenoid 31 is excited by the output signal of the operating condition detection devices such as the air flow sensor 3, the opening switch 4a, the engine rotation speed detection device 7, and the electronic control means 6, and the diaphragm 26 is moved upward to open the nozzle 24, and the negative pressure in the negative pressure chamber 20 is diluted with the atmosphere to be reduced.

Therefore, the diaphragm 17 is moved downward by the force of the spring 23, and the valve body 19 closes the opening 13a, reducing the amount of returning fuel to zero.

Therefore, the pressure of the fuel in the pressure chamber 18 becomes relatively high, increasing the pressure of the fuel supplied to the injection valve 5 and increasing the differential pressure with the pressure inside the intake pipe.

As a result, the amount of fuel injection can be increased by the amount of increased pressure difference without increasing the opening/closing time of the injection valve 5, making it possible to inject a large amount of fuel and ensure maximum output.

On the other hand, during low-speed, low-load operation, the on-off duty of energizing the solenoid 31 is reduced to the extent that the plunger 30 does not move upward, or it is completely stopped, so the diaphragm 26 is in the downward movement position. , valve body 28
throttles or closes the nozzle 24.

As a result, dilution of the atmospheric air against the negative pressure in the negative pressure chamber 20 is suppressed, and the negative pressure becomes relatively large, moving the diaphragm 17 upward and opening the opening 13a.

Therefore, part of the fuel in the pressure chamber 18 returns to the tank through the return passage 13, and the fuel pressure supplied to the injection valve 5 decreases.

Due to the decrease in fuel pressure, the differential pressure with the intake pipe pressure becomes small, so the fuel injection amount can be relatively reduced, and as a result, the fuel injection amount can be reduced without controlling the injection valve opening time using extremely small pulses. This makes it possible to extremely reduce the amount of fuel, making it possible to perform fine adjustments with high precision during low fuel injection.

Therefore, depending on the engine operating conditions, the solenoid 3
1, and by diluting the negative pressure acting on the fuel pressure regulator 14 with the atmosphere, the fuel pressure can be controlled and the differential pressure with the intake pipe pressure can be changed. Even though the dynamic range is small, it is possible to inject fuel over an extremely wide flow rate range, and the optimal fuel amount can be supplied to each operating condition with high precision, and the engine load fluctuates dramatically during sudden acceleration and deceleration. Even in such cases, the fuel pressure is controlled immediately in response to the load fluctuations, thereby improving acceleration performance or preventing wastage of fuel during deceleration.

In addition, as an actual control method, the control signal given to the solenoid 31 is turned on and off at a constant frequency of 10 to 60H2, and the time ratio of this on and off is varied.
The opening and closing time of the nozzle 24 is controlled proportionally, and this is used as the average opening ratio of the nozzle to control the amount of diluted air introduced.

In addition, 3B is a central magnetic body, 44 is a movable iron core, 35 is a spring, 40 is an air filter, and 39 is a comb cover.

In addition, in this example, the intake air amount, throttle valve opening, and rotation speed were used as devices for detecting engine operating conditions.
Other elements may also be used.

Furthermore, it is of course possible to adopt other configurations as the specific configuration of the fuel pressure adjustment mechanism.

Therefore, according to the fuel injection device of the present invention, a control signal is sent to the solenoid valve that controls the operating negative pressure of the fuel pressure adjustment mechanism, which turns on and off at a predetermined frequency, and whose on-off time ratio changes depending on the operating conditions. Since the fuel pressure supplied to the fuel injection valve is optimally controlled, it is possible to perform optimal fuel injection over the entire operating range of the engine and to reduce the dynamic range of the fuel injection valve. Stable operating characteristics allow fuel injection to be controlled with extremely high accuracy over the entire range, and the quick response allows fuel injection to be performed with high accuracy even in transient operating conditions.

Although the present invention is conveniently applied to single point injection, it can also be applied to other multiple injection valve devices.

[Brief explanation of drawings]

FIG. 1 is an overall view of the device of the present invention, and FIG. 2 is a sectional view of the fuel pressure regulating device. 1... Engine body, 2... Intake pipe, 3.
... Air flow sensor, 4 ... Throttle valve, 5 ... Fuel injection valve, 6 ... Electronic control means, 7 ... Rotation speed Detection device, 8...
...fuel pressure adjustment mechanism, 9...tank, 10.
...Pump, 11.12 ...Passage, 13
... Return passage, 14 ... Diaphragm type fuel pressure adjustment section, 15 ... Electromagnetic negative pressure control section.

Claims (1)

[Scope of utility model registration request] An operating condition detection means for detecting operating conditions of an internal combustion engine, an electronic control means for calculating a fuel supply amount based on a signal from the detection means, a fuel injection valve for injecting fuel according to the control output, and In a fuel injection device equipped with a fuel pressure adjustment mechanism that controls the pressure of fuel supplied to a fuel injection valve, the fuel pressure adjustment mechanism includes a negative pressure operation type diaphragm fuel pressure adjustment section and a negative pressure operation type diaphragm fuel pressure adjustment section. and a negative pressure control section having a solenoid valve to be controlled, and provides an on/off drive signal of a predetermined frequency to the solenoid valve via the electronic control means, and determines the on/off time ratio from the operating condition detection means. A fuel injection device for an internal combustion engine, characterized in that the fuel pressure is controlled by diluting the operating negative pressure with the atmosphere by changing it based on an output signal.