JPS6329159Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a drive device for reducing noise during idling of an electromagnetic fuel injection valve that injects and supplies fuel into an intake manifold of an internal combustion engine.

<Prior Art> As a conventional electromagnetic fuel injection valve, there is one shown in FIG. 1, for example.

To explain this, a needle valve 3 is housed in a nozzle body 2 held at the tip of a housing 1.The housing 1 is attached to an intake manifold (not shown) via a bracket (not shown), and the nozzle body 2 is installed in the intake manifold. It's coming. The needle valve 3 is biased to the left in the figure by a spring 4, and the seat portion 3a at the tip of the needle valve 3 is seated on the seat portion 2a of the nozzle body 2 to close the valve. and,
When a predetermined voltage is applied to the electromagnetic coil 5 held in the housing 1 and the iron core 6 is excited, the iron joint 7 attached to the needle valve 3 is attracted by the iron core 6, and the stopper part of the needle valve 3 is attracted. The valve is opened by lifting (lift amount...L) until the valve 3b comes into contact with the stopper plate 8.

However, in such a conventional electromagnetic fuel injection valve, when the valve is opened, the stopper portion 3b of the needle valve 3 comes into contact with the stopper plate 8, which generates an impact sound, and this impact noise becomes harsh especially when the valve is idling. It was one of the sources of noise when idling.

<Purpose of the invention> The present invention was devised in view of these conventional problems, and its purpose is to reduce the noise caused by the impact sound generated when the electromagnetic fuel injection valve opens during idling. .

<Configuration of the device> Therefore, the present device focuses on the fact that lowering the voltage applied to the electromagnetic coil of a fuel injection valve reduces the collision energy between parts and reduces the sound pressure level, and provides a voltage conversion circuit that reduces the voltage applied to the electromagnetic coil when the engine is idling in response to a signal from an idle detection device that detects the engine's idle state.

<Example> Examples will be described below.

Since the structure of the electromagnetic fuel injection valve is as shown in FIG. 1, its explanation will be omitted, and the circuit diagram in FIG. 2 will be explained.

Fuel injection valve 11 (more specifically, its electromagnetic coil 5)
A voltage is applied from a power source to the relay contact 12 through a normally closed relay contact 12 and a transistor 13, and a voltage drop resistor 14 is connected in parallel to the relay contact 12. . The relay coil 15 of the relay contact 12 is connected to a power source via an idle switch 16 as an idle detection device that is closed during idle. here,
A voltage conversion circuit 17 is configured by the relay coil 15, its contacts 12, and the resistor 14. Further, the transistor 13 is made conductive by an output pulse (fuel injection pulse) from the control unit 18 for a time determined by the pulse width.

Therefore, when not idle, idle switch 1
6 is open, the relay contact 12 is closed, and therefore the applied voltage is applied to the fuel injection valve 11 when the transistor 13 is conductive without being dropped.

Also, when idle, the idle switch 16 closes and the relay coil 15 is energized, and the relay contact 12
is opened, so current flows through the resistor 14 side. This resistor 14 causes the applied voltage to drop, and the transistor 13
This voltage drop is applied to the fuel injection valve 11 when conduction occurs. For example, a power supply voltage of about 14V drops to about 10V.

As a result, the electromagnetic force of the electromagnetic coil 5 is weakened, the needle valve 3 is opened slowly, the collision energy between the needle valve 3 and the stopper plate 8 is reduced, the sound pressure level at the time of collision is lowered, and when idling. The noise of the fuel injection valve 11 can be reduced.

Incidentally, FIG. 3 shows the relationship between the voltage applied to the fuel injection valve 11 and the sound pressure level according to experiments conducted by the present inventors, and it was confirmed that the sound pressure level decreases as the applied voltage decreases.

Incidentally, it is conceivable that reducing the applied voltage causes a response delay when opening the valve, reducing the effective injection time and reducing the fuel injection amount, but this type of electromagnetic fuel injection valve driving device has Since it has a device that corrects changes in the injection flow rate of the fuel injection valve due to fluctuations in power supply voltage, the injection amount can be appropriately corrected.

That is, the control unit 18 receives various signals from an air flow meter, a crank angle sensor, an oxygen sensor, etc., and adjusts the injection amount (fuel injection valve 11
The pulse width (pulse width of the output pulse) Ti is calculated as shown in the following equation.

Ti=Tp×COEF×α+Ts Here, Tp is the basic injection amount and Tp=K×Q/N. K is a constant, Q is the intake air flow rate, and N is the engine speed. COEF is various correction coefficients. α
is an air-fuel ratio feedback correction coefficient for air-fuel ratio feedback control. Ts is a voltage correction amount, which is used to correct changes in the injection flow rate of the fuel injection valve 11 due to fluctuations in the power supply voltage.

Therefore, the voltage at the connection point A between the relay contact 12, the resistor 14, and the transistor 13 is input to the control unit 18, and the voltage correction amount Ts is set based on the voltage at the connection point A. Then, by correcting the pulse width of the output pulse to be longer, it is possible to eliminate the problem that the effective injection time is reduced due to a delay in response caused by lowering the voltage applied to the fuel injection valve 11 during idling. If expressed as a flowchart, it would look like Figure 4.

In this embodiment, the voltage conversion circuit 17 is configured by the relay coil 15, its contacts 12, and the resistor 14, but it goes without saying that various methods can be adopted, such as using a transistor instead of the relay coil 15 and its contacts 12. .

<Effects of the invention> As explained above, according to the invention, by reducing the voltage applied to the electromagnetic coil of the electromagnetic fuel injection valve when the engine is idling, the needle valve is opened slowly and the gap between the parts is reduced. The impact energy is alleviated and the sound pressure level is lowered, so that the noise of the fuel injection valve during idling can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an electromagnetic fuel injection valve, Fig. 2 is a control circuit diagram showing an embodiment of the present invention, and Fig. 3 is a longitudinal sectional view showing an electromagnetic fuel injection valve.
The figure is a diagram showing the sound pressure level of the operating sound with respect to the voltage applied to the injection valve when the electromagnetic fuel injection valve is operated, and FIG. 4 is a flowchart showing injection amount control of the electromagnetic fuel injection valve. 2... Nozzle body, 3... Needle valve,
5... Electromagnetic coil, 12... Relay contact, 14...
...Resistor, 15...Relay coil, 16...Idle switch, 17...Voltage conversion circuit.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine equipped with an electromagnetic fuel injection valve that is attached to an intake manifold and injects fuel by suctioning open a needle valve housed in a nozzle body using an electromagnetic coil, an idle detection device that detects the idle state of the engine is used. An electromagnetic fuel injection valve drive device for an internal combustion engine, comprising a voltage conversion circuit that reduces the voltage applied to the electromagnetic coil during idling based on a signal.