JPS63295830A - Fuel injection device - Google Patents

Abstract

PURPOSE:To enable an engine speed to be accurately estimated even when the first speed detector causes a trouble, by providing the second speed detector which estimates the engine speed from a pulsation of pressure in an intake and exhaust pipe. CONSTITUTION:The speed of an engine 1, when it is normal, is detected by the first speed detector 2, and its detecting signal is input to an injection control arithmetic part 4. The first speed detector 2, when it causes a trouble due to some cause, is switched to the second speed detector 3 by a selector circuit 21. And detecting a pulsation of pressure in an exhaust pipe 6 by a pulsation detector 7 and estimating the speed of the engine 1 through an engine speed converter circuit 8, the second speed detector 3 inputs a signal, corresponding to this speed, to the injection control arithmetic part 4. Accordingly, even when the speed detector 2 causes a trouble, fuel injection of a fuel injection device main unit 5 is continuously controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronically controlled fuel injection device.

(Prior Art) This type of electronically controlled fuel injection device captures the engine rotation speed as an electrical signal in order to control the amount of fuel injected, etc. , an electromagnetic pickup sensor is used.

An example of this is the one shown in Japanese Patent Application Laid-open No. 61-149546, in which a gear is engaged with the rotating shaft of the engine, and a pick-up sensor placed opposite the gear detects the strength of magnetism. A pulse signal corresponding to the engine rotation speed is obtained.

(Problem to be solved by the invention) However, if the above-mentioned rotation detection device fails, it becomes impossible to obtain data regarding the engine rotation speed, making it impossible to control the amount of fuel injected, and rendering the engine inoperable. There was a risk of falling.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a fuel injection device that can accurately estimate the engine rotation speed and maintain a good operating condition even if a rotation detection device connected to the engine fails. is the issue.

(Means for solving the interstitial point) However, the gist of the present invention is to provide a fuel injection device that takes in the engine rotational speed and uses it as a factor for controlling the injection amount. The engine includes a first rotation detection device that detects the number of rotations, and a pulsation detection means that detects pressure pulsations in an intake and exhaust pipe connected to the engine.

The present invention includes a second rotation detection device that detects the rotational speed of the engine using the output signal of the pulsation detection device, and a switching device that switches to the second rotation detection device.

(Operation) Therefore, if the first rotation detection device fails,
If the second rotation detection device is used, the engine rotation speed can be estimated from the pressure pulsations in the intake and exhaust pipes, and fuel injection control can be performed regardless of whether or not there is a failure in the first rotation detection device. The above-mentioned problems can be achieved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the fuel injection device has a first rotation detection device 2 provided on an engine 1 and a second rotation detection device 3 provided separately from the first rotation detection device 2. The output signal obtained from the detection device is inputted to an injection control calculation section 4 consisting of a microcomputer, and injection control of the fuel injection device main body 5 is performed.

The first rotation detection device 2 has a well-known configuration, and includes a gear engaged with the rotating shaft of the engine 1 and a pickup sensor provided opposite to the gear. A signal corresponding to the actual rotational speed of the engine 1 is output by detecting teeth arranged at a desired interval on the top with a pickup sensor.

The second rotation detection device 3 includes a pulsation detection means 7 provided in an exhaust pipe 6 connected to the engine 1, and a rotation speed conversion circuit 8 connected to the pulsation detection means 7. As 7, an oxygen sensor 9 as shown in FIG. 2, for example, is used to detect the amount of oxygen and determine the injection amount.

This oxygen sensor 9 has an oxygen pump cell 11 provided at the tip of a housing 10, and also has an oxygen pump cell 11 disposed in the middle of the housing 10.
A first cavity 13 is formed surrounded by an oxygen pump cell 11, a housing 10, and an oxygen detection cell 12. Oxygen pump cell 11
Exhaust gas in the exhaust pipe 6 is introduced through a capillary 14 formed in the exhaust pipe 6. Further, a second cavity 15 is formed surrounded by the oxygen detection cell 12 and the housing 10, and the atmosphere is introduced into the second cavity 15. And oxygen sensor 9
The entire body is heated by a heater 16 and maintained at a temperature that provides optimum responsiveness. Further, both surfaces of the oxygen pump cell 11 and the oxygen detection cell 12 are coated with first to fourth electrodes 17a to 17d made of platinum, for example. The first electrode 17a is connected to one output terminal 18a, and the second and third electrodes 17b.

17c is grounded, and the fourth electrode 17d is connected to the operational amplifier 19.
is connected to one input terminal of the Further, the output terminal of the operational amplifier 19 is connected to the second output terminal 18b, and is also connected to the first output terminal 18a via a resistor 20. Note that the signal input to the operational amplifier 19 is compared with a preset slice level V. As a result, the absolute oxygen partial pressure in the first cavity 13 is detected, and this detection signal varies according to the pressure in the trachea 6 even if the oxygen partial pressure ratio in the exhaust pipe is constant. .

Therefore, the output signals obtained from the output terminals 18a and 18b of the oxygen sensor 8 will vary depending on the rotational speed of the engine 1 because the pressure inside the exhaust pipe 6 is pulsating due to the exhaust gas discharged from each cylinder of the engine 1. This results in a waveform as shown in FIG. 3 with a proportional period.

The pulsating signal from the above-mentioned pulsation detection means 7 is inputted to the rotation speed conversion circuit 8, the period of the signal is calculated by the rotation speed conversion circuit 8, and the rotation speed of the engine 1 is estimated based on this period. A signal corresponding to the estimated rotational speed is output.

The detection output from the second rotation detection device 3 is selectively introduced into the injection control calculation unit 4 via a switching circuit 21 that is switched by the output from the injection control calculation unit 4.

The switching circuit 21 includes a movable contact 22 whose one end is connected to the injection control calculation unit 4, and first and second fixed contacts 23a and 2 which are connected to the first and second rotation detection devices 2 and 3, respectively.
3b, and an excitation coil 24 for switching the movable contact 21. Normally, the other end of the movable contact 22 is connected to the first fixed contact 23a.

On the other hand, the injection control calculation section 4 calculates the target injection amount based on the rotational speed of the engine 1 and the accelerator position detected by the accelerator sensor 25, and calculates the target injection amount based on the amount of residual oxygen in the exhaust pipe 6 detected by the aforementioned oxygen sensor. The injection amount is estimated and the injection amount of the injection device main body 5 is corrected to the target injection amount. Furthermore, when the injection control calculation unit 4 determines that the normal signal from the first rotation detection device 2 is no longer input,
The injection control calculation unit 4 outputs the signal to the switching circuit 21 to switch the movable contact 22 to the second fixed contact 23b.

In the above configuration, under normal conditions, the rotation speed of the engine 1 is detected by the first rotation detection device 2, the detection signal is input to the injection control calculation section 4, and the calculation section 4 controls the fuel injection device main body 5. The fuel injection amount is controlled. If the first rotation detection device 2 fails for some reason, it is switched to the second rotation detection device 3 by the switching circuit 21, and the pressure inside the exhaust pipe 6 is detected by this second rotation detection device 3. The rotation speed of the engine 1 is estimated, and a signal corresponding to this rotation speed is input to the injection control calculation section 4. Therefore, even if the first rotation detection device fails, the fuel injection control of the fuel injection device main body 5 can be continued.

In this embodiment, the oxygen sensor 8 is used as the pulsation detecting means 7, but any sensor that can detect the pulsation of pressure inside the exhaust pipe 6 may be used. For example, a pressure sensor may be used as the exhaust pipe 6. It may also be installed on the surface of the device to obtain its output.

Further, although the pulsation detection means 7 is provided on the exhaust pipe 6, it is not limited thereto, and similar effects can be obtained even if it is provided on the intake pipe.

(Effects of the Invention) As described above, according to the present invention, even if the first rotation detection device provided in the engine fails,
Since the second rotation detection device accurately estimates the engine rotation speed from the pressure pulsations in the intake and exhaust pipes, it is possible to maintain a good operating condition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a pulsation detection means used in the same. FIG. 3 is a characteristic diagram showing the relationship between time and output voltage of the pulsation detection means same as above. ...Engine, 2...First rotation detection device, 3...
-Second rotation detection device, 5...Fuel injection device main body, 6
...trachea, 7...pulsation detection device. Figure 1 Figure 2 Figure 3 Time □

Claims (3)

[Claims] 1. A fuel injection device that captures engine rotation speed as a factor for controlling injection amount includes a first rotation detection device installed in the engine to detect the engine rotation speed; and a first rotation detection device installed in the engine to detect the engine rotation speed; a second rotation detection device having a pulsation detection means for detecting pressure pulsation and detecting the engine rotation speed using an output signal of the pulsation detection means; and a switching means for switching to the second rotation detection device. A fuel injection device characterized by comprising: 2. 2. The fuel injection device according to claim 1, wherein the pulsation detection means comprises an oxygen pump type oxygen sensor provided in the exhaust pipe. 3. 2. The fuel injection device according to claim 1, wherein the pulsation detection means comprises a pressure sensor attached to an intake and exhaust pipe.