JPS6039461Y2 - electronic fuel injection system - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electronic fuel injection device for internal combustion engines.More specifically, the invention relates to an electronic fuel injection device for internal combustion engines. This invention relates to a type fuel injection device.

A conventional electronic fuel injection device includes a rotation speed detection unit connected to a crankshaft of an engine, and a target injection amount calculation circuit into which at least a rotation speed signal output from the rotation speed detector is input. , the optimum injection amount at each time corresponding to the rotational speed is calculated in a target injection amount calculation circuit.

Then, a predetermined fuel adjustment member is controlled by an electric actuator according to the calculation result, and thereby the injection amount is electronically controlled.

Therefore, in this type of electronic fuel injection device, if a failure occurs in the rotational speed detecting section and the rotational speed cannot be detected, control becomes completely impossible and the engine has to be brought to a halt.

However, especially in the case of a vehicle, if the engine became completely inoperable, it would be impossible to move the blade with one's own blade, which was extremely inconvenient.

As this type of prior art, for example, Utility Model Application Publication No. 55-645
As disclosed in Publication No. 2, there is a device that detects the actuator drive current of an electronic governor and stops the current supply when the value of the detected current is equal to or higher than a predetermined value.

Although this bulletin does not mention what happens when the rotation sensor fails, in electronic governors, if the rotation sensor fails and the rotation signal is no longer input, the rotation speed becomes zero in the control system. Therefore, excessive current continues to flow through the actuator to increase the rotation speed.

The present invention was devised in view of the above circumstances, and its purpose is to enable emergency operation even if the rotation speed detector fails at low cost and without extensive modification of the device. An object of the present invention is to provide an electronic fuel injection device that can perform the following steps.

The features of the present invention, which are distantly related to the above object, include a rotation speed detection means for generating a rotation speed signal related to the engine rotation speed;
At least an injection amount control section that responds to the rotational speed signal and adjusts the fuel injection amount so as to obtain an optimal fuel injection amount according to the operating condition of the engine, and a fuel injection valve control section that controls the fuel injection advance angle. In an electronic fuel injection device equipped with a needle valve lift sensor for detecting lift timing of the needle valve, a preliminary rotation speed signal corresponding to the rotation speed is output based on an output signal from the needle valve lift sensor. fault detection means for detecting the occurrence of a fault in the rotation speed detection means; and switching means for selectively inputting either the rotation speed signal or the preliminary rotation speed signal to the injection amount control section. and means for controlling the switching of the switching means to select the preliminary rotational speed signal instead of the rotational speed signal when a failure of the rotational speed detection means is detected in the failure detection means. be.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows a block diagram of a control section of an embodiment of an electronic fuel injection device according to the present invention.

This control section is an example of a distribution type fuel injection pump, and includes an injection amount control section 1 and an injection timing control section 2.

The injection amount control section 1 is for controlling the position of the control sleeve 3, which is a fuel injection amount adjustment member, so that the optimum fuel injection amount can be obtained according to the operating condition of the internal combustion engine. It is provided with theoretical injection amount data 4 in which various information indicating the amount is inputted as an electric signal.

In the illustrated embodiment, the information indicating the operating state includes an accelerator signal S□ indicating the accelerator position, a water temperature signal S2 indicating the engine cooling water temperature, a fuel temperature signal S3 indicating the fuel temperature, and rotation speed data from the changeover switch 10. D1 is input, and based on this information, the optimum fuel injection amount according to the current operating condition is calculated, and theoretical injection amount data D2 indicating the calculation result is output from the theoretical injection amount calculation circuit 4.

A rotation sensor 5 is provided to supply rotation speed data D1.

The rotation sensor 5 is separated from a gear 7 fixed to the crankshaft 6 of the engine and an electromagnetic pickup 8, and the electromagnetic pickup 8 is attached to cogs 7a to 7d provided on the outer periphery of the gear 7 corresponding to the top dead center. A predetermined pulse-like signal is obtained from the electromagnetic pickup 8 by approaching and separating.

The sensor output signal S from the rotation sensor 5 not only indicates the top dead center timing of the engine but also indicates the rotational speed, and is inputted to the rotational speed calculation circuit 9 as rotational speed information.

The rotation speed calculation circuit 9 outputs a rotation speed signal indicating the rotation speed of the engine based on the sensor output signal S.
5 is applied to one input contact 10a of the changeover switch 10.

As will be described in detail later, when the rotation sensor 5 is working normally, the changeover switch 10 is switched as shown by the solid line in the figure, and the rotation speed data is used as the rotation speed data D1 to calculate the theoretical injection amount. It is input to circuit 4.

Further, in this case, the changeover switch 11 provided on the output side of the theoretical injection amount calculation circuit 4 is switched as shown by the solid line.

Therefore, the theoretical injection amount data D2 is directly input to the sleeve position calculation circuit 12, the position of the control sleeve 3 necessary to obtain the theoretical injection amount indicated by the theoretical injection amount data D2 is calculated, and the result is This is output as sleeve position data D3, and converted into analog data by the D/A converter 13.

Analog data from the D/A converter 13 is the target signal S6
F is input to the adder 14, where it is added with the sleeve position signal S7 from the sleeve position sensor 15 that detects the position of the control sleeve 3 with the polarity shown,
An error signal S8 is output according to the difference between the target sleeve position indicated by the target signal S6 and the actual sleeve position indicated by the sleeve position signal S7.

The error signal S8 is processed in the PI control circuit 16, converted into a signal for proportional/integral control, and then inputted from the pulse width modulator 17.

The pulse width modulator 17 outputs a drive pulse signal S9 whose duty ratio changes according to the signal from the PI control circuit 16, and this drive pulse signal S9 is applied to the control sleeve 3.
is applied to the W actuator 18 for positioning.

Control sleeve 3 by electromagnetic actuator 18
When the position of S7 changes, this change causes the sleeve position signal S7 to change.
is fed back to the adder 14 as a change in , and thereby the position of the control sleeve is controlled so that the difference indicated by the error signal S8 becomes zero, that is, the actual sleeve position matches the target sleeve position. .

On the other hand, the injection timing control section 2 is for controlling the timer 19 so as to obtain the optimum injection timing according to the operating state of the internal combustion engine, and is configured to generate an actual injection timing signal indicating the actual fuel injection timing. Injection timing calculation circuit 20 that outputs SIO
and a target injection timing calculation circuit 21 which receives various information indicating the operating state of the engine and outputs a target injection timing signal Sll indicating the optimum injection timing at that time.

A sensor output signal S4 is input to the injection timing calculation circuit 20 as a signal indicating the top dead center timing, and a sensor output signal S4 is inputted from the lift sensor 22 that detects the lift timing of the needle valve of the fuel injection nozzle (not shown) of the injection pump. A lift timing signal S12 is input.

The lift timing signal S1° is a signal indicating the injection start timing. Therefore, in the injection timing calculation circuit 20, the timing T indicated by the lift timing signal S1□,
and the top dead center timing indicated by the output signal S.

The actual injection timing is calculated from the difference between the actual injection timing signal S
Output IO.

In addition to the sensor output signal S4, the target injection timing calculation circuit 21 receives a water temperature signal S2, a fuel temperature signal S3, and an injection amount signal S13 indicating the injection amount, and calculates and outputs the injection amount based on these signals. The target injection timing signal S11 is input to the adder 23, where it is added to the actual injection timing signal SIO with the polarity shown, and an error signal S14 is generated according to the difference between the two.
is output.

Error signal S1. is input to the PI control circuit 24, and its output signal S15 is input to the pulse width modulator 26 via the changeover switch 25.

The pulse width modulator 26 outputs a drive pulse signal SI6 whose duty ratio changes according to the signal from the changeover switch 25, and outputs a drive pulse signal SI6 whose duty ratio changes.

is applied to the solenoid valve 27 for controlling the timer 19.

When the timer 19 is operated by the electromagnetic valve 27 and the injection timing changes, this change causes an actual injection timing signal S.

is fed back to the adder 23 as a change in , and thereby the timer 19 is controlled so that the actual injection timing matches the target injection timing.

A preliminary rotation speed calculation circuit 28 is provided for the purpose of ensuring normal operation of the injection amount control section even if the rotation sensor 5 has a failure for some reason and information regarding the rotation speed cannot be obtained from the rotation sensor 5. There is.

The lift timing signal S1□ from the lift sensor 22 is input to the preliminary rotation speed calculation circuit 28 as information regarding the engine rotation speed, and this lift timing signal S1
Based on □, an alternative preliminary rotation speed signal S17 corresponding to the rotation speed signal salt is output.

This preliminary rotation speed signal S17 is applied to the other input contact 10b of the changeover switch 10.
Either signal S17 or signal S17 is selected and taken out as rotation speed data D1.

Here, with reference to FIG. 2, the rotational speed signal 1 and the preliminary rotational speed signal S17 will be explained.

The rotational speed signal S is a signal generated in the rotational speed calculation circuit 9 based on the sensor output signal S shown in FIG. 2a.

The sensor output signal S is a collection of a pair of pulse signals obtained from positive and negative pulses obtained each time each blowfish of the gear 7 approaches and leaves the electromagnetic pickup 8, and each of the pair of pulse signals has a positive and a negative pulse. The zero level point between the positive and negative pulses exactly indicates the top dead center timing.

The rotational speed calculation circuit 9 rectifies and waveforms this sensor output signal S4, converts it into a pulse signal PS1 as shown in FIG. 2, calculates the rotational speed based on the period of this pulse signal, and calculates the Output the results as digital data.

On the other hand, the lift timing signal S1□ is a signal having a period exactly eight times that of the sensor output signal S, as shown in FIG. It indicates the timing.

This lift timing signal S1□ is shaped into a sudden wave in the preliminary rotation speed calculation circuit 28 in the same way as the sensor output signal S, and the rotation speed is calculated based on the period of the shaped signal, and the calculation result is converted into digital data. Output.

When the rotation sensor 5 is operating normally, the rotation speed signal salt is taken out as the rotation speed data D1, and when a failure occurs in the sensor 5, the preliminary rotation speed signal 517 is taken out as the rotation speed data D1.
A sensor check circuit 29 and a switching control circuit 30 are provided for the purpose of switching and controlling the changeover switch 10 so as to take out the image as a signal.

A sensor output signal S is inputted to the sensor check circuit 29, and the generation state of this sensor output signal S is monitored.
As a result, when it is detected that a failure has occurred in the rotation sensor 5, a failure occurrence signal 518 is sent from the sensor check circuit 29.
is output and input to the switching control circuit 30.

The level of the switching signal S19 from the switching control circuit 30 is at the 1LJ level when the fault occurrence signal S18 is not output, and becomes the 1H level when the fault occurrence signal S18 is output.

This switching signal S1. is applied to the changeover switches 10, 11.25, and when the level is r''LJLJ level, each changeover switch is in the state shown by the solid line in the figure, and in the case of JHJ level, each changeover switch is in the state shown by the dotted line in the figure. shall be.

The switching control circuit 30 further sets the preliminary rotation speed calculation circuit 28 into an operating state only when a failure occurs in the rotation sensor 5,
When the rotation sensor 5 is operating normally, it outputs a control signal S9 for making the preliminary rotation speed calculation circuit 28 inactive.

Therefore, if there is no failure in the rotation sensor 5,
The node rotation speed calculation circuit 28 becomes inactive, and rotation speed data is taken out from the changeover switch 10 as rotation speed data D1.

On the other hand, if a failure occurs in the rotation sensor 5, the control signal S20
The preliminary rotation speed calculation circuit 28 becomes operational, and the preliminary rotation speed signal S17 is supplied to the injection amount control unit 1 as the rotation speed data D1. Even if there is, the injection amount control can be performed without any problem.

Further, the changeover signal S19 causes the changeover switch 11 to be switched as shown by the dotted line, and the theoretical injection amount data D2 is supplied to the sleeve position calculation circuit 12 via the injection amount limiting circuit 31.

The injection amount limiting circuit 31 suppresses the value of the theoretical injection amount data D2 to a predetermined upper limit value even if the value is equal to or greater than a predetermined upper limit value, and suppresses the value of the theoretical injection amount data D2 to a predetermined upper limit value even if the value becomes less than a predetermined lower limit value. This is a circuit to suppress the value to the lower limit.

Therefore, even if the control becomes incomplete due to the operation based on the preliminary rotational speed signal S □It is possible to prevent data from disappearing and becoming uncontrollable.

When a failure occurs in the rotation sensor 5, the supply of the sensor output signal S to the injection timing control section 2 is also stopped.

The injection timing calculation circuit 20 calculates the injection timing at the pulse signal PS2 (FIG. 2C) that rises at each zero level point of the sensor output signal S corresponding to the top dead center timing of the engine (FIG. 2C) and the lift timing signal S1□. Pulse signal PS3 that rises at each level change point described above indicating the start timing
(Fig. 2 e), the injection start timing T1 and the top dead center timing T2 are detected from these pulse signals, and the actual injection timing is calculated based on the difference between them. Therefore, the sensor output signal S, Due to the stoppage of the supply of fuel, the injection timing control section 2 also becomes inoperable.

A preliminary control signal generation circuit 32 is provided to ensure operation of the injection timing control section 2 even if a failure occurs in the rotation sensor 5.

The preliminary control signal generation circuit 32 converts the preliminary control signal S21 into an injection amount signal for controlling the pulse width modulator 26 so as to obtain an injection timing that roughly matches the optimum injection timing obtained by control using the output signal S15. This is a circuit generated based on S13.

This preliminary control signal S2. is input to the selector switch 25, and when a failure occurs in the rotation sensor 5, the selector switch 25 is switched as shown by the dotted line, and the output signal S
The preliminary control signal S21 is sent to the pulse width modulator 26 instead of I5.
is input.

Therefore, even if the sensor output signal S is no longer output, the injection timing control section 2 does not become inoperable and can operate almost normally.

The control signal S20 is also input to the preliminary control signal generation circuit 32, and this circuit 32 is activated only when a failure occurs in the rotation sensor 5.

According to such a configuration, even if rotation speed information cannot be obtained from the rotation sensor 5 due to a failure of the rotation sensor 5, this condition is immediately detected and the preliminary rotation speed signals S, 7 from the preliminary rotation speed calculation circuit 28 are output. Since it is given to the injection amount control unit 1 as the rotation speed data D1, the device does not become uncontrollable.
Injection amount control can be reliably continued.

It should be noted that the present invention can be applied not only to a distribution type fuel injection device but also to a size type fuel injection device.

According to the present invention, as mentioned above, if a failure occurs in the rotation speed detection section and regular rotation speed information cannot be obtained, a pre-installed device is installed to detect this condition and detect the fuel injection timing. Since the preliminary rotation speed signal is obtained based on the signal from the needle valve lift sensor installed in the system, and the injection amount is controlled based on this signal, emergency operation of the fuel injection system can be performed without extensive modification of the existing equipment. , it is possible to significantly improve the reliability of the device without increasing the economic burden.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the control section of an embodiment of the present invention;
Figures a through 2e are signal waveform diagrams for explaining the operation of the block diagram shown in Figure 1. 1... Injection amount control section, 2... Injection timing control section, 3... Control sleeve,...
... Rotation sensor, 9 ... Rotation speed calculation circuit, 1
0...Selector switch, 22...Lift sensor, 28...Preliminary rotation speed calculation circuit, 29.
...Sensor check circuit, 30...Tune switching control circuit, Dl...Rotation speed data, D2...
Theoretical injection amount data, S, ... sensor output signal,
S5...Rotation speed signal, S9...Drive pulse signal, SI2...Lift timing signal,
S17... Preliminary rotation speed signal, Sl8...
・Failure occurrence signal, Sl,...Switching signal.

Claims (1)

[Scope of utility model registration request] a rotation speed detection means for generating a rotation speed signal related to the rotation speed of the engine, and adjusting the fuel injection amount in response to at least the rotation speed signal so as to obtain an optimal fuel injection amount according to the operating condition of the engine. In an electronic fuel injection device comprising an injection amount control unit and a needle valve lift sensor for detecting lift timing of a needle valve of a fuel injection valve to control an injection advance angle of fuel, means for outputting a preliminary rotational speed signal corresponding to the rotational speed based on an output signal of the rotational speed; failure detection means for detecting occurrence of a failure in the rotational speed detection means; a switching means for selectively inputting one of the two to the injection amount control section; and a switching means for inputting one of the two inputs to the injection amount control section; an electronic fuel injection device comprising means for controlling switching of the switching means so as to select.