JPS6214702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic fuel injection device for an internal combustion engine,
In particular, the present invention relates to a device for manually adjusting the idle mixture ratio of an engine during assembly inspection of a vehicle.

In electronic fuel injection systems for internal combustion engines, variations in idle mixture ratio due to product variations pose a problem. Since this variation becomes apparent only after the combination of parts is determined, it is possible to determine whether the mixture is rich or thin by inspecting the mixture ratio during vehicle assembly inspection. Therefore, it is desirable to provide a manual idle mixture ratio adjustment means in a location that is easily accessible from the outside of the completed vehicle.

In an electronic fuel injection system having a conventional flap type air flow meter, a bypass passage is provided which bypasses the main air passage having a flap. This passage forms a passage that is not metered by the flap, and adjusts the bypass passage opening area to adjust the idle mixture ratio. The inlet opening of the bypass passage is structured so that a large amount of air flows into the bypass passage when the flap is almost fully closed, and almost no air flows into the bypass passage when the flap is nearly fully opened. Although this structure is easy to adjust, it is complicated.

In electronic fuel injection systems that use hot wire flow meters, the hot wire is easily affected by the flow field, so
It is undesirable to form a bypass passage within the flow path. Therefore, a means different from a flap type flowmeter is required.

An object of the present invention is to provide an idle mixture ratio adjustment device that does not use a bypass passage in an electronically controlled fuel injection device, and to provide a simple structure adjustment device that is suitable for devices using hot wire flowmeters.

In order to achieve the above object, the present invention calculates the pulse width for opening and closing the fuel injection valve based on various operating states of the fuel injection valve and the internal combustion engine, and calculates the opening delay of the fuel injection valve. In an electronically controlled fuel injection system comprising a control unit incorporating a circuit for setting a valve opening delay correction pulse to be corrected and adding it to the pulse width, there is provided a means for detecting an idling operation state, and an easy operation outside the control unit. and a manual adjustment circuit for the valve opening delay correction pulse width, which is connected to the circuit that sets the valve opening delay correction pulse only during idle operation according to the detection result of the above means. By manually adjusting the delay correction pulse, the mixture ratio during idling operation can be manually adjusted.

As described above, in the present invention, the manual adjustment circuit that adjusts the circuit in the control unit is installed in an easy-to-work place, for example, on the intake flow meter, and the variable resistor of the manual adjustment circuit is manually adjusted. By adjusting the valve opening delay correction pulse width determined by the control unit, the mixture ratio at idle is manually adjusted.

As a result, the mixture ratio during idling operation can be easily adjusted to the required range, the final inspection of the vehicle is significantly facilitated, and the range of variation is reduced.

The present invention does not require machining of the intake pipe, and does not affect the accuracy of hot wire flowmeters or the like.

Embodiments and drawings illustrating the present invention will be described.

The figure shows a device for manually adjusting the idle mixture ratio during vehicle assembly inspection in the electronically controlled fuel injection system according to the present invention. The illustrated circuit shows a part of the circuit of the control unit 1, and shows a circuit for determining the voltage _V1 which determines the valve-opening delay correction pulse T _S of the fuel injection valve. Note that the valve opening delay correction pulse Ts compensates for changes in the effective valve opening time (actual fuel injection time) due to changes in the valve opening delay time of the fuel injection valve that occur in response to changes in the power supply voltage. It has a value that increases linearly as the power supply voltage decreases.

When the idle switch 2 linked to the throttle valve (not shown) is off, the transistors Tr ₁ and Tr ₂ in the control unit 1 are off, and the voltage V ₁ is
It is determined by R ₁ , R ₂ , R ₃ and the voltage of the power supply 4.
Therefore, when the voltage of the power supply 4 changes, the voltage _V1 changes, and the value of the valve opening delay correction pulse Ts changes accordingly to compensate for the valve opening delay due to fluctuations in the power supply voltage. Further, when inspecting the completion of the control unit 1 itself, the required voltage _V1 can be obtained by adjusting the resistor _R2 , and the required pulse width can be obtained by the fuel injection control circuit IC.

In the present invention, resistors R ₅ and R ₆ , which are normally built into the control unit 1, are installed within the air flow meter 3. When the idle switch 2 is turned on, the transistors Tr ₁ and Tr ₂ become conductive, and the resistors R ₄ , R ₅ , and R ₆ are connected between the power supply 4 and the ground, and the resistor R ₄ is a resistor.
Connected in parallel with R ₁ and R ₂ to increase the voltage V ₁ , and resistor R ₅ ,
R ₆ is in parallel with resistor R ₃ to reduce voltage V ₁ . By selecting the values of resistors R ₄ , R ₅ , and R ₆ , the value of voltage V ₁ during idling is compared with the value during steady operation, and the required change is made, and the valve opening delay correction pulse of the injection valve is Change the value of T _S.

In order to adjust the variation in the mixture ratio during idling during vehicle final inspection, the valve opening delay correction pulse T _S is changed by adjusting the resistor R ₅ .
As a result, the necessary adjustment to the overall injection pulse width of the fuel injection valve is performed, and the mixture ratio becomes richer or leaner to reach the desired mixture ratio.

In the present invention, the resistor _R5 is connected to the control unit 1.
By attaching it to the intake flow meter 3 separately from the intake flow meter, it is possible to easily manually adjust the mixture ratio during idling operation at the time of final inspection of the vehicle, reducing variations in the mixture ratio and reducing the emission of harmful exhaust gas components. can be reduced.

Since the installation adjustment of the resistors R ₅ and R ₆ is unrelated to the intake air amount and the air flow path, no turbulence is caused in the air flow, and the measurement accuracy of the hot wire flowmeter is not adversely affected.

The resistor _R5 is a circuit that affects the voltage _V1 only when the idle switch 2 is on, and does not affect other operating regions.

Although the circuit of the present invention is extremely simple, it is possible to easily adjust the mixture ratio at idle without requiring any modification to the intake pipe, and it can be done in a convenient location as an external manual adjustment during the final inspection of the vehicle. It is.

[Brief explanation of the drawing]

The figure is a diagram showing a mixture ratio adjustment circuit during idling of the electronically controlled fuel injection system according to the present invention. Explanation of symbols: 1... Control unit, 2... Idle switch, 3... Intake flow meter, 4... Power supply.

Claims (1)

[Claims] 1 Calculate the pulse width for opening and closing the fuel injector based on various operating conditions of the fuel injector and the internal combustion engine, and set a valve opening delay correction pulse to correct the opening delay of the fuel injector, In an electronically controlled fuel injection system equipped with a control unit having a built-in circuit for adding to the pulse width, a means for detecting an idling state is provided at an easily operated location outside the control unit, and the detection result of the means is and a manual adjustment circuit for the valve opening delay correction pulse width which is connected to the circuit that sets the valve opening delay correction pulse only during idle operation according to the valve opening delay correction pulse. An electronically controlled fuel injection device characterized by the ability to manually adjust the mixture ratio during idling operation.