JP2514319B2 - Fuel injection control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device, and more particularly to a fuel injection control device capable of increasing and correcting an injection amount of fuel by a temperature change of a fuel system.

[Prior Art] A so-called electronically controlled fuel injection device, which electrically detects the operating state of an internal combustion engine as a fuel injection amount setting factor and controls the fuel injection amount, has a basic injection amount setting factor such as engine speed and intake. The air amount is detected, and the intake air temperature, atmospheric pressure, power supply, cooling water temperature, voltage, carburetor throttle valve opening, etc. are detected as correction injection amount setting factors. The basic injection amount is set by the basic injection amount setting factor, and the corrected injection amount is set by the corrected injection amount setting factor to correct the basic injection amount according to the operating state.

[Problems to be Solved by the Invention] In such a fuel injection device, it is generally considered that the influence of the injection amount due to the temperature change of the fuel system such as the fuel temperature and the fuel injection valve is small, and the cost of adding the fuel temperature sensor is low. In consideration of the rise, the injection amount was not corrected due to the temperature change of the fuel system.

However, there is a limit to the conventional correction based on the intake air temperature or the cooling water temperature, and when outside the correction range, the air-fuel ratio may become too thin or rich, and engine stall may occur. In particular, recently, as the layout of the engine room space of a vehicle or the like becomes more compact, the temperature of each part rises, and the temperature in the vicinity of the fuel injection valve may become high to generate fuel vapor. Therefore, similarly to the vaporizer fuel supply device, it is necessary to take measures against fuel vapor to avoid engine stall and deterioration of restartability due to vapor lock.

Therefore, a temperature sensor is incorporated in the pressure regulator of the fuel system, or a temperature sensor is incorporated in the fuel passage as disclosed in Japanese Utility Model Laid-Open No. 60-66845 and Japanese Patent Laid-Open No. 60-145438. However, there are disadvantages that the temperature sensor is incorporated to increase the cost and complicate the structure, and the device cannot be downsized.

[Object of the Invention] Therefore, an object of the present invention is to make it possible to increase and correct the fuel injection amount by the temperature change of the fuel system without the need for a temperature sensor, and to reduce the size without increasing the cost and complicating the structure. It is to realize the obtained fuel injection control device.

[Means for Solving Problems] In order to achieve this object, the present invention detects a rise time of an electric signal for driving the fuel injection valve, which changes due to a temperature change of a fuel injection valve portion of a fuel system. A control circuit for determining whether or not the temperature at which the fuel vapor is generated based on the detection signal and controlling the fuel injection amount to be supplied to the internal combustion engine to be increased when the temperature at which the fuel vapor is generated is provided. Characterize.

[Operation] According to the configuration of the present invention, the control circuit detects the rising time of the electric signal for driving the fuel injection valve, which changes due to the temperature change of the fuel injection valve part of the fuel system, and the fuel vapor is detected by this detection signal. Is determined to be the temperature at which the fuel vapor is generated, and if the temperature is the temperature at which the fuel vapor is generated, the fuel injection amount is controlled to be increased. That is, since the electric resistance increases and decreases as the temperature rises and falls, the rise time of the electric signal for driving the fuel injection valve changes between low temperature and high temperature. When the temperature at which the fuel vapor is generated due to this changing rising time, the fuel injection amount can be appropriately controlled according to the temperature change of the fuel injection valve portion that constitutes the fuel system by increasing and correcting the fuel injection amount. .

[Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 1, 2 is a fuel injection valve, 4 is a control circuit,
6 is an arithmetic processing unit, 8 is a transistor, and 10 is an external resistor. The external resistor 10 may be omitted if the internal impedance of the fuel injection valve 2 is high.

The arithmetic processing unit 6 of the control circuit 4 receives signals such as an intake air amount for which a basic injection amount should be set and an engine speed, and signals such as an intake air temperature and a cooling water temperature for which a corrected injection amount should be set. The arithmetic processing unit 6 calculates the injection time from these input signals and turns on the transistor 8. Of transistor 8
When ON, the fuel injection valve 2 injects a quantity of fuel according to the calculated injection time.

However, when the temperature of the fuel injection valve 2 portion rises or the temperature of the fuel rises and fuel vapor is generated in the fuel injection valve 2, the amount of fuel corresponding to the injection time becomes equal to the amount of fuel corresponding to the injection time. The fuel is not injected, the air-fuel ratio becomes thin, and an engine stall or a start-up rattling occurs. Further, there is a problem that the restartability deteriorates.

Therefore, in this embodiment, a low resistance (shunt resistance) 12 and a comparator 14 are connected to the point E of the transistor 8 and the increase correction is performed according to the rise time of the electric signal for driving the fuel injection valve 2. Avoid thinning of the air-fuel ratio.

That is, the voltage / current waveform at the point E is as shown in FIGS.
It looks like. A voltage is applied to the fuel injection valve 2 for the injection time loss τ to inject a quantity of fuel according to the injection time τ.
When the temperature of the fuel or the fuel injection valve 2 itself is low, the electric current flows like f1 due to the decrease in electric resistance, and the rise time t1 until reaching the reference current value c is short. On the other hand, fuel and fuel injection valve 2
When the temperature of itself rises, the electric resistance increases and the current flows like f2, and the rise time t2 becomes longer. Therefore, the rising time t until the reference current value c is reached by the comparator 14
And the fuel amount is increased and corrected.

For example, as shown in FIG. 3, the rise time of the current f2 at a high temperature at which fuel vapor is generated and the air-fuel ratio is thinned is set as a rise time longer than the rise time t1 of the current f1 at a low temperature at which fuel vapor is unlikely to be generated. When the time t2 is detected, the calculation processing unit 6 calculates the injection time τ to increase and correct the fuel amount, and turns on the transistor 8. This allows
It is possible to prevent thinning of the air-fuel ratio due to fuel vapor at high temperatures. For this reason, engine stall and deterioration of restartability can be avoided.

On the other hand, when the rise time t1 shorter than the rise time t2 is detected, there is no possibility of thinning the air-fuel ratio by the fuel vapor, and therefore the fuel amount is not increased and corrected. Therefore, it is possible to control to an appropriate air-fuel ratio. Moreover, since the temperature sensor is not required, the cost can be reduced and the structure can be prevented from becoming complicated, and the device can be downsized.

As shown in FIG. 4, the increase correction may be steplessly controlled in proportion to the rising time, or stepwise correction control may be performed depending on whether the increase correction is necessary or unnecessary. This allows
The air-fuel ratio can be stabilized. Further, this increase correction can be performed together with another correction, for example, the intake air temperature, etc., to improve the drivability of the internal combustion engine at the time of starting, warming up, or after complete warming.

Incidentally, in this embodiment, when the rise time is long, the fuel is controlled to be increased and corrected.
That is, it goes without saying that it is possible to control the fuel so that the amount of the fuel is increased steplessly or stepwise depending on the temperature of the fuel injection valve 2. By controlling in this way, it is possible to control to a more appropriate air-fuel ratio.

Further, in this embodiment, the voltage drive type fuel injection valve has been described, but the present invention can be similarly applied to the current drive type fuel injection valve. In this case, since the shunt resistor and the comparator may be unnecessary, it is possible to further avoid the cost increase and the complexity of the structure and achieve the miniaturization of the device.

In addition to the electric signal of the fuel injection valve, it is also possible to cause an electric signal to flow through the fuel passage, the passage pipe body, etc., and increase the amount of fuel to be corrected by changing the rise time of the electric signal.

[Effects of the Invention] As described above, according to the present invention, the fuel injection control device causes the control circuit to increase the rise time of the electric signal for driving the fuel injection valve, which changes according to the temperature change of the fuel injection valve portion of the fuel system. Is detected and whether or not the temperature is the temperature at which the fuel vapor is generated is determined based on this changing rising time. If the temperature is at the temperature at which the fuel vapor is generated, the injection amount is increased and corrected. As a result, this fuel injection control device can appropriately control the injection amount according to the temperature change of the fuel injection valve portion that constitutes the fuel system without requiring a temperature sensor, so that engine stall and deterioration of restartability are prevented. It can be avoided. Moreover, since this fuel injection control device does not require a temperature sensor, the device can be downsized without increasing the cost and complicating the structure.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is a block diagram of a control circuit, FIGS. 2 (a) and 2 (b) are waveform diagrams of voltage and current, FIG. 3 is a control flowchart, and FIG. 4 is current. FIG. 4 is a graph showing the relationship between the rising time and the amount of fuel increase. In the figure, 2 is a fuel injection valve, 4 is a control circuit, 6 is an arithmetic processing unit, 8 is a transistor, 12 is a shunt resistor, 14 is a comparator, τ is an injection time, and t1 · t2 is a current rise time.

Claims (1)

(57) [Claims] 1. A rise time of an electric signal for driving the fuel injection valve, which changes due to a temperature change in a fuel injection valve portion of a fuel system, is detected, and it is judged whether or not the temperature is a temperature at which fuel vapor is generated by the detection signal. A fuel injection control device comprising a control circuit for controlling to increase and correct an injection amount of fuel supplied to an internal combustion engine when the temperature of the fuel vapor is generated.