JPS62189343A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To conduct a smoke control having a service life longer than a light transmission type sensor, by computing a smoke concentration according to an output from an O2 sensor provided in an exhaust passage of a Diesel engine, and adjusting a fuel injection quantity. CONSTITUTION:A control unit 18 receives detection values from an O2 sensor 14 provided in an exhaust passage 13, an engine speed sensor 19, an acceleration sensor 20 and a water temperature sensor 21, etc., and computes a smoke concentration according to the output from the O2 sensor 14 and the engine speed. A governor 23 including a position sensor 24 and an actuator 25 is controlled through a servo amplifier circuit 2, and an injection quantity of a fuel injection pump 1 is so adjusted as to reduce the smoke concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for controlling the injection amount of fuel used in a diesel engine.

(Prior Art) Conventionally, as shown in, for example, Japanese Utility Model Application Publication No. 50-119811, a sensor for detecting smoke concentration is provided in the exhaust passage of a diesel engine, and the output of this sensor is fed back to perform injection. It is known to control the amount and regulate the smoke concentration to below a predetermined value.

(Problem to be Solved by the Invention) However, in the above conventional example, since a light transmission type sensor is used for detecting the smoke concentration, the light source may be blocked by the adhesion of graphite, etc. in the exhaust passage. There has been a problem in that the amount of light reaching the sensor gradually decreases over the period of use, making accurate detection impossible, and as a result, controlling the injection amount cannot be performed accurately either.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned conventional problems and provides a fuel injection control device that can accurately detect smoke concentration regardless of the period of use and thereby accurately control injection amount for smoke countermeasures. The challenge is to do so.

(Means for Solving the Problems) As shown in FIG. The smoke concentration calculation means 100 calculates the smoke concentration according to the smoke concentration calculation means 100, and the injection amount adjustment means 200 adjusts the injection amount of fuel injected into the engine 2 according to the calculation result of the smoke concentration calculation means 100. It is characterized by Also, the main application tube 2
The invention is such that a rotation sensor 19 for detecting the rotation speed of the engine 2 is added to the first invention, and the smoke density is corrected based on the output of the rotation sensor 19.

(Function) As shown in FIG. 4, there is a certain relationship between oxygen concentration and smoke concentration. Therefore, in the present invention, the oxygen in the exhaust gas of the engine 2 is measured by the oxygen sensor 14, the smoke concentration calculation means 100 calculates the smoke concentration according to the output from the oxygen sensor 14, and the calculated smoke The amount of fuel to be adjusted by the injection amount adjusting means 200 can be controlled by determining whether the current injection amount is appropriate based on the concentration, and therefore the above object can be achieved.

(Example) In FIG. 2, a fuel injection pump 1 is, for example, a distribution type, and a plunger 4 is connected via a cam plate 5 to a drive shaft 3 that rotates using an engine 2 as a drive source. It rotates and reciprocates within the barrel 6, and the pump chamber 7
The fuel inside is discharged through a delivery valve 8. This discharged fuel is transferred to the injection valve 1 via the injection pipe 9.
0 and is injected from this injection valve 10 into the combustion chamber of the engine 2. In this engine 2, air is taken in through an intake pipe 11, the fuel and air are mixed and combusted, and the resulting exhaust gas is exhausted to the outside through an exhaust passage 13 in an exhaust pipe 12. There is.

This exhaust passage 13 is provided with an oxygen sensor 14 . This oxygen sensor 14 is a well-known sensor made of zirconia or the like, and outputs an electrical signal according to the amount of oxygen in the exhaust passage 13. The output signal from this oxygen sensor 14 is then input to the control unit 18.

The control unit 18 includes a well-known microcomputer, and in addition to the output signal from the oxygen sensor 14 described above, the control unit 18 receives a rotation speed signal N0 from a rotation sensor 19 that detects the engine rotation speed, and an accelerator position signal A p from an accelerator sensor 20. p and a temperature signal T from a water temperature sensor 21 that detects the water temperature of the engine. Then, these input signals are processed to obtain a target control signal, which is output to the servo amplifier circuit 22. This servo amplifier circuit 2
2, the target control signal described above is compared with a position signal from a position sensor 24 provided in the governor 23, which will be described later, and the target control signal is corrected and amplified.
output to the actuator 25.

The governor 23 has an actuator 25 that constitutes the injection amount adjusting means 100 shown in FIG. 1, and an output shaft 27 rotates according to the amount of current applied to the actuator 250. The output shaft 27 is provided with an eccentric retaining portion 28, and a control sleeve 29 is fitted onto the plunger 4 on the retaining portion 28. The axial movement of the control sleeve 29 changes the injection amount. It is adjustable.

In FIG. 3, an example of the control operation by the control unit is shown, and the control unit starts execution of processing from start step 30 when the power is turned on. In the next step 31, the read-only memory
The maximum injection amount QF is calculated based on the full Q characteristic stored in the (ROM), and the value is stored in the random access memory.
(RAM), and the next step 32
Proceed to. In this step 32, the idle injection amount Qi is determined based on the idle characteristics stored in the same <ROM.
is calculated, the value is stored in the same RAM0 predetermined location, and the process proceeds to the next step 33. In this step 33, the driving injection amount Q is calculated based on the driving characteristics stored in the ROM, and the value is stored at a predetermined location in the RAM.Then, the process proceeds to the next step 34, The above-mentioned idle injection amount Q and running injection amount QR are added and the resulting value is stored as QD.When the process further proceeds to the next step 35, this value QD and the maximum injection it ct y obtained in step 31 are added. are compared and the minimum value is selected and stored as Ql.

Step 36 is for calculating the smoke concentration. As shown in FIG. 4, if the rotation speed N2 is constant, the oxygen sensor output and the smoke concentration are approximately inversely proportional, and as the rotation speed increases Even if the oxygen sensor output is the same, the smoke concentration will increase as the engine changes, so this characteristic is stored in the ROM in advance, and the value obtained from the oxygen sensor output is corrected by the rotational speed to obtain the smoke concentration EC. The smoke density calculation means 200 shown in FIG. 1 is constructed from step 36.

The actual smoke concentration EC obtained in this step 36 is compared with the value set as the maximum value that should be allowed in the next step 37, and if the smoke concentration EG is larger than the setting, it is necessary to regulate the injection amount. If the smoke density EC is smaller than the setting, the process proceeds to step 39 because there is no need to regulate it. That is, in step 38, the error between the actual smoke density EG and the setting is calculated and converted to D (however, D
1), and in the next step 40 step 35
Multiply Q obtained by this error, and use the result as Q. L
IT. On the other hand, in step 39, step Q1 is repeated as is. U.

Proceeding to the next step 41, the start injection amount QsT is calculated based on the starting characteristics stored in the ROM, and in the next step 42 it is determined whether or not the mode is the start mode. If the mode is the start mode, the next step is performed. Go to 43 and Q
Q for 3T. U, but if the mode is not the start mode, the process jumps to step 44. Then, in this step 44, Q. The LIT is outputted to the servo amplification circuit described above, the process is completed in step 45, and this process is repeated.

(Effects of the Invention) As described above, according to the present invention, the oxygen sensor is provided in the exhaust passage of the engine to detect the oxygen concentration of the exhaust gas,
Since the actual smoke concentration is calculated based on this, it is possible to accurately detect the smoke concentration even after a long period of use, which makes it possible to control the injection amount appropriately, and to prevent smoke. It is valid.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an outline of the present invention, FIG. 2 is a block diagram showing an embodiment of the same, and FIG. 3 is a flowchart showing an example of the control operation of the control unit used in the embodiment of the above.
FIG. 4 is a characteristic diagram showing the relationship between the output of the oxygen sensor, the smoke concentration, and the rotation speed. 2... Engine, 13... Exhaust passage, 4... Oxygen sensor, 19... Rotation sensor, 100... Injection amount adjusting means, 200... Smoke concentration calculating means.

Claims (2)

[Claims] 1. An oxygen sensor provided in the exhaust passage of the engine, a smoke concentration calculation means for calculating smoke concentration according to the output from the oxygen sensor, and fuel injected into the engine according to the calculation result of the smoke concentration calculation means. 1. A fuel injection control device comprising: injection amount adjusting means for adjusting the injection amount of the fuel injection control device. 2. an oxygen sensor provided in an exhaust passage of an engine; a rotation sensor for detecting the rotation speed of the engine; a smoke concentration calculation means for calculating a smoke concentration according to outputs from the oxygen sensor and the rotation sensor; A fuel injection control device comprising: injection amount adjusting means for adjusting the injection amount of fuel injected into the engine according to the calculation result of the concentration calculation means.